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Tuberific Q&A from Bob Carver's eBay auctions

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I didn't have time to search but found this transcript of the Q&A from one of Bob's Tube Amp auctions on ebay & wanted to get it down for posterity before it is lost forever (If you look closely, Bob published his Sunfire email address in here!):

 

"Q: Hi Bob, redstone7 here again from Colorado Springs, I have to ask one more question......is there ever going to be a tube preamplifier offered from your camp right here on E-Bay??? Thanks much, Rob Mar-21-09

 

A: Hi Rob'stone7, not from me ( I should never say never), but James Sauter IS planning to build an exact copy of the preamp I designed for the Silver Sevens long ago. He may be found on the Carver Fest forum. Thanks again, Bob Carver

 

Q: continued,, so now there is being fed to the bias pot a filtered neg. DC, that is decoupled from the filter capacitors, that can change with without the lag that a capacitor would cause. It must have been pretty darn fast because I could hook the amp to a scope,set idle to 15ma. suddenly zap a sinewave to it big enough to drive right up to just before clipping, and the sine wave would instantly appear with out gradually climbing up with flattened tops. That was good enough for me!!!!! I have bailed out of tube equipment, am now making chip amps from the latest audio grade offering from National Semiconductor.. they sound very "tubelike" to me (and many others) Just in time because I am getting too old to manhandle heavy iron. nevertheless I still maintain a keen interest in new ideas in tube technology. I would love to see a schematic of these amps..could you send me one to my email? The 6al5 is a high perveance duo diode.I'm trying to imagine how it is implemented..Neal Mar-21-09

 

A: Hi Neal, I would be happy to send you a schematic....just e-mail me after the auction to remaind me. Don't forget to include your e-mail! Bob

 

Q: Greetings Bob, I have followed you since the Silver 7, and Tim since the EAR, and I can not think of any other two who have added so much good music to the world. In fact reading of the Silver 7 is what got me interested in tubes...again (built my first tube amp in '57 with bits and pieces of discards, but cost drove me to transistors in 65 and cheap speakers masked the difference). Might it be possible for you to come up with a "kit" or built bias 'controller' that would be adaptable to different amps. I have a Meas Baron tri-tube modified which I love, but 1 bias and 1 balance pot to control 6 tubes per side requires frequent tweeking even though I use current matched tubes. It seems there is much interest in a better bias method. I have seen this in questions for the amps you have offered, and in many of the DYI groups as well. Many not be exciting to do, but it is a much needed product, and important tweek for tube amps. I you'd be swamped with sales too cordially, bud Mar-21-09

 

A: Hi 'greg, I too have a pair of vintage Mesa Barons with six 6L6's per mono block amp. Beautiful amps! The 6AL5 DC restorer is the answer to your problem, plus it will stop the DC bounce that inevitably creeps into the system as the grid bias "hunts" under dynamic conditions. E-mail me after the auction and I'll send you the complete fix and the schematic as I used in my Baron. Warmest and best, Bob Carver

 

Q: Hi Bob...thank you for responding to my confusion concerning your bias scheme,,but first I want to say to the bidders:....BID AWAY, BOYS AND GIRLS.I HAVE INDEPENDENTLY DUPLICATED THE ESSENTAL FEATURES AND CAN ASSURE YOU THIS IS THE ONLY WAY TO OPTIMIZE FOR AUDIO QUALITY AND LONGEVITY. SO BID WITH ASSURANCE MORTGAGE YOUR HOME IF YOU CAN GET ONE OR EVEN HAVE A JOB LEFT TO THINK ABOUT IT Ok I think I know where my confusion lies----when I say sliding bias I mean changing the G1 negative voltage....when you say sliding bias you refer to a particular TECHNIQUE to change G1 neg. volt. Consider the neg source half or full wave, there will be a smoothing cap followed by a an RC tage ,followe by maybe another RC smoothing stage..Now follow with a resistor voltage divider WITH NO CAPACITOR ..the center connection now feeds the bias pot..One leg of the volt divider is paralleled with a device that changes resistance with input drive....continued Mar-21-09

 

A: Not exactly, but close enough for Gov'nt work. Keep that brain going 1000 RPM and we can have a scientific discussion about bias off-line. Bob

 

Q: dear Bob....thank you for hanging in there with my audio-amatuer forays into mysteries of tube amps. I don't understand your bias stablization...it doesn't jive with your comments which I quote here "the dc restorer eliminated the need to idle each output tube at 50 watts yielding instead an idle power of 12 watts per tube....It works by keeping the dc componant on each output tube grid the exact value throgh the entire audio signal swing allowing perfect performance up to and even beyond clipping" Well, if by dc componant you refer to the negative bias grid voltage this is exactly how I describe my sliding bias scheme. If your bias scheme doen't shift the negative bias as the amp moves away from idle it will soon run into class B operation and really gross distortion. Your previous response says the bias doesn't slide , but if by slide we mean changing the bias voltage , then it MUST slide to my way of thinking...I'm confused cordially neal Mar-21-09

 

A: Hi '541, ....It jives perfectly with my comments. A sliding bias scheme has too much delay in responding under dynamic conditions OR it has too much control voltage ripple modulation for my taste. Such a scheme must ALWAYS be a compromise between the two. That's because it will have a detector diode, an integrating capacitor, and a time constant comprised of the final smoothing RC filter. The topology is often similar to a meter drive circuit. On the other hand, a DC restorer operates such that the DC value of the waveform on the grid remains where we want it even in the presence of asymmetrical, haversine signals. And its delay time is essentially zero because there is no filter capacitor to charge and therefore no time constant. Works far better, and is far more elegant than a simple and coarse sliding bias circuit. Bob Carver

 

Q: Bob....Come on..Bob..don't you want to explain to the prospective buyers the magic trick of 12 watts idle ( 18ma. at 660 volts anode) per output tube and not slide the bias to lower and lower negative G1 volts under progressively greater dynamic conditions to keep out of class B operation and unlistenable distortion?? ("My dc restorer is not a sliding bias approach, rather its purpose is to keep the DC value on the control grid at design center etc etc" your words , not mine) we are all waiting with breathless anticipation cordially Neal in Oregon Mar-21-09

 

A: Continued next following.

 

Q: Hi Bob, can you say a bit more about how this amp sounds? Can you elaborate on "the sound: This amplifier stands with a small handful of the world's great vacuum tube amplifiers" a bit more, especially sound-wise, which of the great amplifiers are most similar to your amp? Thank you, Frank Mar-21-09

 

A: Hi '211k, I would say my own Silver Seven's, my Subsequent Silver Sevens with extra output tubes and dual screen regulators. (Two 6550's per amp.) The $30,000 Manley amps, and the Mesa Barons at 150 watts. I've limited this to vintage amps. Hope it helps, Bob Carver

 

Q: ...which output tubes are used in this amp, 6550's or the kt88's, the write up refers to both articles tim depravacini/stu hegeman and yourself, is there any difference between the carver/pravacini mono's and carver/hegeman mono amps? thank you! david Mar-21-09

 

A: Hey old friend, these amps use KT88's. The difference is in the front end; these use 12AT7's, 12AX7's, and 6AL5's with KT88's. The Hegeman units use 6AW8's, 12BH7's, and 6AL5's with 6550's. I cannot answer the question which one do I like better because it's just like asking which of your children do you love more. I love them both the same, even though they each possess distinctive audio personalities! Bob Carver

 

Q: What an honour to be able to ask you a question,Bob. How do you think these amps would match up with Apogee Duetta Signatures' current and voltage loads, and would you recommend running both MT ribbons and bass panels with them ? (Trying to get away from present biamping with chip amps on bass and tube hybrids on MT ribbon and into a more coherent one-amp sound, if that makes sense). Your vintage pair here have come up on the Apogee users' website as one possible ultimate amp for Apogees, which would be wonderful for one who, like me, is just looking for that final and permanent piece of his system. Mar-21-09

 

A: Hi 'fitte, I prefer the one-amp coherent sound unless the amplifier is not powerful enough to avoid clipping and overload on some of your music. This amp has been designed to run the Apogee Scintilla one ohm speaker....I really worked hard to get it to do that. So it should be a walk-in-the-park for the Duetta. The power increases as the impedance decreases....up to 300 watts, just what the Apogee needs and loves. I would not bi-amp here, perhaps bi-wire with heavy gauge for the bass panels and finer wire for the ribbons. Try it both ways. Bob Carver

 

Q: Hello Bob, I was reading your writings here and you mentioned that your friend Stu liked the 6550's better than the KT-88's but I see you opted for the 88's on this design,is there a specific reason because of the overall design or is it more about personal preference? The funding is not here to bid on your current effort but I'm right in the middle of re-tubing my MC-275's and your input would be greatly appreciated , Thanks, Rob McRae in Colorado Springs Mar-20-09

 

A: Hi 'stone 7, Remember that Stu was designing tube amps long ago and the KT88 was very new on our shores. At the time, the mighty 6550 was supreme, was considered the best and the finest, and was used by all the great designers back then. However, the KT88 was on its way. I love both tubes and would be happy with either, but I have a giant stash of NOS vintage KT88's to use from my museum. Bob

 

Q: Hello Mr. Carver, is there any comparison between these beauties and the legendary Silver series of tube amps you created long ago ?? Could they realistically be produced again, given the growing high-end audio gear market, especially in the tube sector ? Since I was unable to attend CarverFest last year, I'm still hoping to view the Q&A session that was recorded , I submitted questions for you and have yet to learn what your answers were ! Maybe this year !!! Respectfully yours, silver7t1 Mar-20-09

 

A: Hi '7t1, Oh no! I never got your questions, or perhaps I did and have forgotten. Try again at bob.sunfire@gmail.com., The relationship between the two amplifier designs is what I call crystalized knowledge. The Silver Sevens are similalar to the 520 circuit, whereas these have the cicuit described above. You bet this year! Bob Carver

 

Q: Hello Bob I consider it a honor to even ASK you a question, let alone receive an answer!LOL Anyways I'm wondering about the transformers, can you disclose what they are for primary Z? Also I don't see a choke in your PSU, is it CRC filtered then? Thanks WOT Mar-20-09

 

A: Hi 'tour, I have hooked them up to match four output tubes, so in this design, since I have six of them they are intentionally underloaded which allows them to operate such that an easy 180 watts is obtained, and is the reason the output power can increase when havily loaded with a difficult to drive speaker load. All CRC filtering, and with so much that a vintage designer woul find it difficult to believe.

 

Q: Bob - Oops, forgot that the text mentioned the bias control. I am fascinated by the driver. It looks like a 12AX7 sized T-6 tube, short envelope. I would be interested in finding out what it is. Again, it looks like a 5687. Tim Smith Mar-19-09

 

A: It's a 12AT7 double mica, military frame grid NOS tube and can easily drive three outputs per plate with a 33,000 ohm resistor following. See the RCA tube manual. Excellent question. Bob

 

Q: Bob- Will you ever decide to release this tube amp design for production commercially? Mar-19-09

 

A: Hi '1, I would love to but that would take more vintage parts than I have to spare. I don't know what I'll do when I run out of output transformers, but I'll think of somthing....maybe I'll just clone a Partridge or something, as I still have my old transformer winding machine.Warmest and best, Bob Carver

 

Q: Hey Bob---just let 'rama know he can find me by going to my eBay page. He can go to the site map, click on find members, and put in tubular_joe. Thanks! Mar-19-09

 

A: Got it! Bob

 

Q: Bob - Magnificent amps! A few questions but don't the feel the need to answer if you'd be compromising proprietary information. It looks like the KT88 grids are fed from the 6AL5 cathodes - can't tell, the chassis photo is grainy. Also, are all of the KT88s controlled by a single bias pot (rear of amp?) or does your circuitry handle bias needs - can't tell if there's a bias pot at the rear. Is the driver tube a 5687? That strikes as about the only small tube (non-Russian) that would have the ability to drive a sextet of KT88s. I've built amps for several years, essentially all with regulated pentode output stages; think they sound the best. I recently finished a 45 watt/channel rig that uses Russian 6P41S vertical amp tubes run at 460 on the plates and 185 on the screens, If you're interested I can send photos; email address is ***edited***. Good luck selling these, I hope they find a good home. Thanks, Tim Smith Mar-19-09

 

A: This is going to be a fast answer...I'm on a two minute time-out computer. The drive comes from a 12AT7. The 6AL5 IS connected to the grids to control the D.C. All the output tubes are cintrolled by a single pot, not for balance so much as for the ability to trim the soundstage envelopment. And yes I would love to see see photoes.

 

Q: It is a pleasure and a privilege to view your tube amp and to read your Q&A. You are truly a designer for the people, reminiscent of when you took the Stereophile challenge and made affordable gear sound like reference. Sorry for the off topic question but I am dying to know if there is a postscript to the challenge. Cheers! Mar-19-09

 

A: Hi 'it, Well, the only postscript that comes to mind is that after all these years, the original article is still being posted around the world in several languages and many forums. It suprises me to this day that a single article by J. Gordon Holt has had so much staying power. Thank you for writing, Bob Carver

 

Q: Dear Bob, Another thought I have is concerning your comment that only four types of circiut designs for tube amps have ever been invented. With your design being a 5th circuit, would it have been possible to design this circuit 50 years ago with the type of componets available at the time or would you have had to add a bunch more tubes and circuits to accomplish the same design 50 years ago. Am I making any sense? Thank you again, Frank E. Mar-19-09

 

A: Hi Frank, What a great question. sinc`e this amp is built of vintage parts, it would absolutely have been possible 50 years ago. Even the 6AL5 was around back then. But neither Tim nor I were. And yes, you make a lot of sense! Bob Carver

 

Q: Dear Bob, I have a quick question, for my own information. I like the look of your pots. Are they a pot and or transformer combo that you made. My only guess is maybe McIntosh?? And if your quad wiring and DC Restorer are available to look at on a schematic. ( if your pats. are secure and filed of course). I am not going to copy it at all, just interested, of course! Thanks again, Frank E. Mar-19-09

 

A: Hi '632, I don't remember where I got the pots....it was so long ago. Remember, I was old when Atlantas sank! I'll send you a schematic if you remind me after the auction, and you are welcome to copy it to build an amp if you wish. Thanks for writing, Bob Carver

 

Q: Hi Bob How many dB of Global Feedback do you use in these amps? Is the feedback on the secondary of the OPT? Mar-19-09

 

A: Hi 'Plies, Our amp uses the classical amount of 20 dB and if the output transformer is good enough to support a full twenty dB a switch on the front can change it to 11 db, a contemporary amount often used by modern amplifier designers. I prefer 20 dB. I prefer the full twenty if the output transformer is good enough to support it."

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I captured Q&A from the other Bob Carver tube amp auctions:
 
Question & Answer Answered On
Q:  Dear Bob, So good of you to stand with your amp and talk with all the tube lovers. When all is said and done its all about the community, the designs and the friendships. I have a review project that may make you smile. The 700 series 1. Its a wonderful amplifier and its magic still holds fast after all these years. I share your belief that there are only a handful of basic circuits but many offshoot iterations of them. I like the old 6bq5 integrateds from Heathkit/dyna/Stromberg...etc. To the point: I've been planning this vintage review of your 700 series 1 for Stereophile and to write an interview standout "sidebar" into the piece. It would be great to chat--when you have a chance drop me an email. Sincerely, Peter Breuninger, Stereophile pbstereophile@aol.com Nov-12-08
A:  Hi Peter, You sure do bring back some great memories; I recently bought a 6BQ5 Stromberg Carlson tube amp taken from an old console designed in the 1950's. It doesn't work, but I plan to fix it up and put it in my audio museum. I can't wait to read your review of my first Phase 700. Thanks for tripping me down Memory Lane, Bob Carver.
Q:  Hi Would you consider shipping this item to Canada? Thanks Art Nov-11-08
A:  Hi 'res, Art, I would be happy to ship these amps to Canada. I went to school at the UBC in Vancouver and spent some very happy time in your land of the blue water dolphin. Thanks for writing, Bob Carver
Q:  Bob, Just curious, why didn't you incorporate a triode option, since usually triode sound does have a very seductive transparent effect. I am using Strathern/EMIT/Magnepan ribbons on my QRS Infinitys and the triode sound makes them sound very unique. Nov-10-08
A:  Hi 'ster I did, as we shall see. Your question is deep, and my answer is as complex as your question is deep. So sit back, stay with me, and enjoy the intellectual and scientific journey. The triode sound owes it's particular characteristic to the fact that when an output tube is connected as a triode, the source impedance of the power amp drops to a very low value - often below 0.50 ohms. That's pure theory, but I happen to own a vintage Soundcraftman 500, pure Williamson, triode connected output section designed by Sid Smith of Marantz 8B and Model Nine fame. I measured it and found confirmation with theory, as well as with it's published specifications. Measured exactly 0.380 ohms. It DID sound different from the pentode sound, but that "seductive transparent effect" depended critically on the loudspeaker. On most of my speakers, including my new Cinema Ribbons and my friend's QRS's, the sound was just stunning with my amps. That's because the DC restorer allows the source impedance of the amp to be adjusted by the rear panel bias control. Sid's 500 sounded great too, but not greater, and of course it only delivered about 23 watts. When an output tube is configured for triode operation, it wastes about 60% of its available power supply voltage due to the fact it cannot pull its plate voltage to ground well. In addition, the plate voltage must be reduced in value to match the maximum permissible screen voltage, further reducing the output power. Bad news all around if you like power. With my amp, The DC restorer, in combination with the bias current adjustment range, allows a very low source resistance(approximately 0.30 ohms for the triode sound),AND more than 180 watts. Most tube amps have a recommended OPTIMUM bias setting for output tube idle current; my amp has a RANGE of recommended idle currents, allowing the sound to be controlled from triode sound to regulated screen(classic tube)sound - my favorite by far most of the time. Great question, Bob Carver
Q:  Hi Mr Carver would you take a money order from me if I win.Thanks Bert. Nov-10-08
A:  Hi '63 Bert, I would be happy to take a money order from you. And if you live close by, I will deliver the amps myself and help set them up with your speakers. Thanks for asking, Bob Carver.
Q:  Bob, Are you the same Bob Carver I met at the Jockey Club Hotel around '75 at the Vegas CES of that year? You had a lot to say then about building amps that would show how an inexpensive design could produce the same quality of sound as the most expensive amps, if it were done using old ideas presented in a new way. Well, it seems that history has proven you did that quite well. This looks like a new version of your old song. Only this time you are using the best of old ideas, old equipment, and old friends to create a new expression of the audio ideals I heard from you 30+ years ago. The question is, why are you selling this one of a kind creation? And, are you planning to go further with this design idea? Will it be a progenitor and standard of a new line of equipment like the Silver Sevens? Or, will this amp stand as a one-off with never another in the audio world to match it? Thanks for your good works over the years, PK Nov-10-08
A:  Hi 'PK, It is I, the very same Bob Carver. When we met at the Las Vegas Jockey Club so long ago, I was introducing my Sonic Hologram, the year was '79 0r '80, and I was just starting my Carver Corp. days. Wow! What a memory you have! As far as going further with this design, I have no intentions, none at all, of building these amps with parts other than from my museum. But I'm not out of parts from my vintage stash yet, so I'm pretty sure I'll be able to build at least one more pair. Thanks for the happy sentiments and deep questions, Bob Carver.
Q:  Dear Mr. Carver, I am very excited to see a pair of amplifiers designed by yourself and Tim De Paravicini. Unfortunately, I am unlikely to be able to afford to purchase them. I do build tube amplifiers for myself, once in awhile, and was wondering if you would be willing to make the schematic available. I'm not enough of an electrical engineer to design amplifiers for myself, and there's not, as you note in your advertisement, a lot of new and interesting designs out there. So it would be very exciting to put together a pair of these amplifiers. Thank you in advance for your response. Ben Nov-10-08
A:  Hi 'fm Ben, I will be happy to make a schematic available to you. The big problem will be finding output transformers good enough for the job. The second problem, though not so tough would be the big power transformer. Let me think about it and I'll try to steer you towards some suitable units. I would sell you a pair of my output transformers but I love them too much to do that. They are pretty special. I've had them since I was in college, and I think I loved them more than my girlfriend. Please contact me after the auction and after I've have had a chance to look around for something that will work okay. You are one courageous man! Good luck, warmest and best regards, Bob Carver
Q:  will you be selling anymore of these in the future, or is this the only set? Im a 22 year old in love with the sound of tube amps and looking for something amazing to add to my collection and listen to. James Nov-10-08
A:  Hi '515, I still have some of my vintage parts left, which I have "stolen" from my audio museum to build these amps. So my answer is I don't really know for sure, but probably will build at least one more set. Since you're 22 years old, I'm extra glad these amps will probably last over 50 years. I love tube amps too! Thanks for writing. Bob Carver
Q:  Does your amp use negative feedback and is it a class a design? Thanks, Jason 574 329-1850 Nov-10-08
A:  Hi 'walker, Yes, this amplifier uses negative feedback; it has a switch on the front panel to choose between classical amounts (20 dB) and contemporary amounts(9 db). Because of the DC restorer circuit, it operates in class A up to about 80 watts, then hands off to class AB for the rest of the way up to its maximum output. Great question. One last thing: This is the fourth pair of these amps that we have put up here on eBay, and during the last auction, I made several commitments to many folks who asked questions. Shortly thereafter my computer was completely scrubbed and I lost all of it! Soooo, if you are one of those folks, please contact me once again and let me know what it was I promised you and this time I will make sure I follow through. I apologize, I have no excuse, only that reason. Bob Carver

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Question & Answer Answered On
Q:  Dear Sir, I am the guy everyone asks to fix things for them. I have tweeked my SS amp as far as it can go and would love to challenge myself with a new construct project like your amps. Living in detroit I find Vintage equipment at hand. So the problem of finding output transformers would be less for me. And I would like to think that they would make a nice match to the pair of Electro Voice Regency speakers I cherish so much. The full upgrade vesion with the T350's, T25's, and SP15's. All 8 Ohm with a crossover made by BEC. Who sells here and can be found on a few of the forums.If I can be included in the Schematics send off I would be honared. repair-tech@charter.net Nov-19-08
A:  Hi 'mp, Wow! I'm finding it difficult to believe how many souls want to build this amp. I almost built a Patrician for a friend last summer- T350, T25, SP12 and two 315's per cabinet, but decided to wait 'till next year. Anyway, your answer is yes, just be certain to contact me after this auction is over. I would be delighted to send you the schematic. Good luck! Bob Carver
Q:  Can the transformer be tapped for 240volts ac use? Would you consider shipping overseas? I have a FedEx a/c to facilitate this. Nov-19-08
A:  Hi 'le8, I CAN make it operate overseas, and yes I have the technology to ship to any place in the world. I'm sure your Fed-Ex account will make things nice and easy, thanks for asking and joining. Warmest and best regards, Bob Carver
Q:  Hello- I have a question regarding negative feedback that turns into positive feedback with some circuits. The question was sent to your gmail address along with a diagram of the squealing circuit. Did you get a chance to look at it yet? I am curious as to what I'm doing wrong. Thank you in advance. Blair Nov-19-08
A:  Hi Blair, I've been out of town, but I'll find that e-mail and contact you this weekend, or Tuesday at the latest. We will fix it for sure! Bob Carver
Q:  Hi, Bob, I am from Hong Kong. Just curious but I am serious, will you and Tim together design and build a power amp best for driving Peter Walker's early QUAD electrostatic speakers, i.e. ESL57 and ESL63. I'll be in the waiting queue. Nov-19-08
A:  Hi 'yyu, I'll ask Tim next week when I return home - the main problem is the time it takes to design it AND get it right. Tim and I both have a love for the old Quads - for me it was the first time in my life I heard an amazing speaker. Perhaps we can tap into that old love of QUADS. Keep your fingers crossed.
Q:  Hi Mr. Carver, If I won the bid is it possible that you could convert the amp to 220V. I intend to use them in Thailand. Thanks. Nov-19-08
A:  I will adapt these amps to operate on 220 volts. No problem. Happy bidding and lots of luck! Thanks for asking, Bob Carver
Q:  Hello Mr. Carver, as a vacuum tube amplifier scratch builder and honoured student of Lance Cochrane, I can really appreciate these two massive units you and Tim have created! Very nice to see you enjoying tube technology. To me, it's just so much more fun in every way than transistors could ever be! Also nice to see that Lance had a hand in getting you involved in the ebay experience. You are a very well respected man in audio, and to own something with your name on it is truly an honour! P.S. Just so you know who I am, you recently saw my work on my new web site. Steve- Peterborough Ontario Canada Nov-18-08
A:  Hi '748, Steve, I saw, admired your work and completely identified with your passion and creative drive to build something better and out of the ordinary. What better place than in the world of vacuum tubes? Your amplifiers are beautiful; each so unique - seems we were both inspired in important ways by Lance. Thanks for your comments, keep up your good works, Bob Carver.
Q:  Hello Mr. Carver, I can't tell you how inspiring it is to see these beautiful amps! I used to design and build tube amps as a hobby in the 60's, and now after 35 years I am back at it again. I am so excited because now we can make them sound even better, and your DC Restorer circuit appears to be a solution to an age old problem. Have you published the details or schematic of your DC Restorer anywhere, or would I be able to get a copy from you? Thanks, John (access_guru) Nov-18-08
A:  Hi 'ru, John, I'll send you a copy about a week after the auction closes. I'm out of town right now (on the road) and I'm following our auction from my hotel room. If you contact me later in about a week or so, I'll send the schematic and a parts list. I have to say, there is nothing more fun than building vacuum tube amps. Thanks for writing, Bob Carver
Q:  Hi, Bob! I have read in your replies that you can share schematic of this amp after auction end. May I ask you the same favor? Nov-18-08
A:  Absolutely! My pleasure. Just don't forget to call after the auction. Thanks for asking, Bob Carver
Q:  Dear Mr. Carver, I am very excited to see a pair of amplifiers designed by yourself and Tim De Paravicini. Unfortunately, I am unlikely to be able to afford to purchase them and was wondering if you would be willing to make the schematic available. i would like to try to build a copy for my self if you don't mind , i was allwayes want a amp from you , so i want to ask if teh scematitic is all i need to get help and do a copy regards yehuda Nov-18-08
A:  Hi '972, Vacuum tube amplifiers are fun to build and listen to; I'm happy to make the plans available, along with some good tube amp counseling along the way as you enjoy the adventures of buiding a pair. My head is swelling - thanks for the accolades - makes my day! Just contact me about a week after the auction is over to help me remember this promise to you. Thanks for writing, Bob Carver.
Q:  Bob, You asked me to ask Ed Dell about publishing the schematic for this beast. [bTW, I changed my EBay ID from "nation_sauna_wholesalers" to this new moniker, "technicalaudio", in case you're wondering]. Here is Ed's reply, verbatim: "Hi Brian Thanks very much for thinking of ax as a path for those interested in Bob Carver's new amp (what a marketing genius he is.) I would be happy to publish the schematic. I would also request permission to use one of the photos he has posted on e-bay (not the one with him eating the apple(or hotdog, however) and also a parts list. He may question adding the parts list since with it people may construct the amp themselves. The smart ones will figure this out without the list, however. This is a great opportunity for us, since every bit of news about ax helps spread the word about DIY. It is nice to have long-term readers who do the creative thinking for you. Thanks Best Ed" (ed@audioxpress.com) I'll let you contact him directly. Thanks! Brian Nov-18-08
A:  Hi 'dio, I e-mailed Ed this morning and said I would be delighted to share these amps with his readers, including schematics, parts list , and helpful hints. If he wishes of course, but I have not heard back from him yet. Many years ago he ran the complete plans for my big Silver Seven tube amp, and I actually met several builders who had built them. I couldn't believe it! But it was true! Thanks for the important idea Brian. Best wishes and warmest regards, Bob Carver.
Q:  Hi:I'm hoping youall can helpme with my telefunkn fome Belg. Everything is in German.Its a Conceritino#7The 110 side of the power supply burned out. Can you be of some help.Is There an out of the unit(radio) power supply THE 220 WORKS THE TUBES COME ON. .Thank you for time Michael D.Ross (760)672-7515 Nov-16-08
A:  Hi birdman, Of course I will help. Contact me about a week after the auction for a scientific discussion about burned out power supplies, and we will almost certainly get your amp up and running. Looking forward to our amplifier science talk, Bob Carver
Q:  hello mr carver-- beautiful pieces! wondered if you have considered making affordable tube gear for those lacking funds to own things of this caliber. i bought one of your 400 amps in the 80's and loved it, bought a 400t a couple years ago from ebay and it was awesome as well. currently using a tube amp from a wonderful fellow that sells his amps on ebay from california you may know. i think that you could sell them as fast as you could make them if you had a similar piece with your name on the front. just a thought. again, beautiful!!-- Nov-16-08
A:  Hi '914, You are making my head swell a bit. Thanks for the kind thoughts - and if the fellow from California happens to be Lance, know that it was he who gave me the idea of doing an eBay amp - it seemed to be lots of fun meeting so many tube amp lovers. Thanks for writing, Bob Carver.
Q:  Mr. Carver: I'm a poor student. Actually, I'm a very good student, but am poor of means. I have always thought highly of many of your products, including the Amazings. I would like to beg a copy of your schematic as well, if you would be so kind. Please put me on your list. Thank you very much. Indeed grateful. --Robbbie Nov-16-08
A:  Hi'piv - Robbie, You are on the list! Please contact me after the auction is over to get your copy. I was a broke student too, so I hope the schematic helps you as much as tube amp schematics helped me when I was a student. Best wishes and warmest regards, Bob Carver.
Q:  Mr. Carver: I'm a poor student. Actually, I'm a very good student, but am poor of means. I have always thought highly of many of your products, including the Amazings. I would like to beg a copy of your schematic as well, if you would be so kind. Please put me on your list. Thank you very much. Indeed grateful. --Robbbie Nov-16-08
A:  Hi'piv - Robbie, You are on the list! Please contact me after the auction is over to get your copy. I was a broke student too, so I hope the schematic helps you as much as tube amp schematics helped me when I was a student. Best wishes and warmest regards, Bob Carver.
Q:  Hi, Bob! I have read in your replies that you can share schematic of this amp after auction end. May I ask you the same favor? Nov-16-08
A:  Hi'_ba, Yes, I would be delighted. Just make sure you contact me about a week after the auction is over and I'll send it to you. I'm out of town for the next ten days and will be answering questions from afar from my hotel room, but I won't have a schematic until I return home. Thanks for writing, Bob Carver
Q:  Dear Bob Carver: I sad to say am in the group that most likely willnot be able to afford the final price of these amps, but must say they are indeed beastiful! (Probably the most beautiful item on EBAY except perhaps the K model Beechcraft Bonanza! Thanks for all thec info I appreciate it Tom Nov-15-08
A:  Hi 3550, Tom, Thank you for the accolades, even thought the Beechcraft IS prettier. Perhaps the last sentiment depends on whether we are pilots or tubaphiles that glow in the dark. I'm glad you liked the techno information - I often think I'm putting all of us to sleep when I go on and on with so much technical stuff. Thanks again for writing and for your comments, Bob Carver
Q:  Hello Mr. Carver, Im down in Seattle and would gladly come pickup the amps and pay cash to avoid all the PayPal Fee's. Is that acceptable? I did read where you said you would come set it up etc. if the buyer was close. If I win these, They will be put away for awhile until my new home is finished and a large listening room is designed around them. About 9 months out right now. Thank You for your consideration. Nov-14-08
A:  Hi '217, So you live in the rain-forest too! Well, if you win, come on over to my place and we can listen here before they begin their long hibernation, to be awakened like Sleeping Beauty with a kiss nine months from now. Best wishes and good luck! Bob Carver
Q:  Hi Bob I'm not an audio engineer type,but I love great sound,BTW your amps look great! How come no American Co. has marketed/made affordable great sounding, self bias (for the wider market)tube integrated? China's doing this, I have bought some Eastern Electric goods and they are fantastic, among others, I think there's a market for it here. Still lots of two channel freaks. Any thoughts? Regards,Eric Nov-14-08
A:  Hi 'rick, I really don't know why American guys don't build integrated tube amps. Personally I think it's a great idea, and I know that in the vintage days it seems that everybody did. Lafayette, Citation, McIntosh, Fisher, Scott Boulevard and on and on endlessly to name a few. I also know there are lots of us two channel folks. HUMMMM? Bob Carver
Q:  Hello Bob I guess you were "just blowing smoke" when you responded to my e-mail promising me that you woulod send me a schematic and pictorial drawing of the last pair of Mono Blocks that you and Tim de Paraficini designed and you and Tubular Joe built) that you sold on e-bay, to use my pair of output transformers Regrds, "jay" Nov-13-08
A:  Hi Jay, Man, am I glad you have e-mailed me! I lost you when I had my computer scrubbed clean of viruses by a computer guy. I goofed up. Anyway, now I have found you again and will send you the schematic just as soon as this auction is over. I promise! Please contact me then via my regular e-mail just to make sure I don't forget. You're back! Yea! Warmest and best regards, Bob Carver.
Q:  Aren't you the same Mr. Carver that proved that a modestly-priced solid-state amp could be made to sound EXACTLY like any other amp, tube-types included? What has changed? Nov-13-08
A:  Hi '618, Yes, it is I, the real Bob Carver. Nothing has changed. What I did at Stereophile so long ago was to show that I could get very, very close. Within one part in better than four ten thousandths, but not EXACTLY. You can read all about it by Googling Carver Audio.com and clicking on "Carver Challenge", or just Google "The Carver Amplifier Challenge" It's surprising to me that after all these years, the article is still being posted in so many places around the world! Thanks for writing, Bob Carver.

 
 
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Q:  NO question, but, as a hi-fi enthusiast who will probably never actually MEET Bob Carver, I wanted to send my kudos to a gentleman who efforts, persistence, and never-ending search for perfection has meant so much to a hobby that so many, of all backgrounds, enjoy. Kudos, Bob. Neil in Kansas. Dec-30-08
A:  Hi Neil '43. Who knows what life holds; you have made my day with your kind cheers and nice smile. Happy new year, Bob Carver
Q:  any chance of getting, buying or otherwise obtaining a circuit diagram for this fine amp? I am not quite in a position to compete for this amp now. thanks, bob m Dec-30-08
A:  Hi sly bob69,I would be happy to send you a circuit diagram. Send me you e-mail and I'll send it within a week of the auction closing. bob.sunfire@gmail.com.
Q:  Mr. Carver, I was diagnosed a few years ago at 28 with a tumor on my acoustical nerve. I started to revisit audio shortly after. Being out of work do to my illness I had to sell off my gear. A great friend of mine has been by my side since day one. He put some funds together and got me a new setup. He couldn't afford this but made it happen. Well I had a fire and lost that gear too. so there he and I were with a passion for audio and no gear. "Life goes on".... A short time ago I found out my dear friend is terminally ill. He is bed ridden until his illness takes its toll. Backing up a bit I have spoken to him about who you are and what you mean to the audio world. He called me frantic last night..."get over here man I have to show you something" So I quickly got some shoes on and headed over. When I got there he was literally jumping up and down.. He couldn't show me this auction fast enough. Sure we cant afford these but it didnt stop us from dreaming...Thank you for that. AMAZING! Dec-30-08
A:  I am silent, and I'm weeping. What a beautiful story; thank you for sharing it with all of us. Bob
Q:  Amps are awsome. I myself also love to design and build tube amplifiers. I would love to meet Bob Carver. Could this be aranged? I would love for him to see my designs and projects. Ron Becker Dec-29-08
A:  Hi '32 Ron, I would love to meet and have a scientific discussion about tube amps; there are few meetings that could possibly be more fun! Come on over to my place or to the Sunfire building if you live close by. Or even if you live far away. Bring your designs, I'll bring mine. If you live too far away, we can even do it by e-mail. Many Cheers, Bob Carver
Q:  Bob and friends, your design here appears well thought out and executed. May I ask, is your .15% THD at 180 watts output a midband measurement only? How do things hold together at your rated 23HZ and say 20KHZ where things usually get hairy? =:-o And in your experience, how audibly important are the ends of the humanly perceived spectrum? :>) JAY Dec-29-08
A:  Hi '4298 Jay, This question is deep and complex, even deeper than you probably think; I love questions like this! Here goes. My (full power) 0.15% THD spec is at one kHz, whereas at 23 Hz it's just below 0.5%, and at 20 kHz it's about 0.35%. My THD analyzer has a 50 kHz measurement filter that helps my measured 20kHz number a bit. My transformer core begins to saturate at 707 volts rms (end-to-end) and 0.043 seconds. Nothing like those old vintage transformers! As far as frequency response goes, I like flat response to the ends, but power response at those ends is far less important, and in fact not important at all in the extreme. As an example of this, consider the RIAA curve, whose POWER response is down approximately -20 dB relative to 1kHz. This means the tweeter of a 200 watt system will never see more than about two watts! We can easily see this in our designs; a woofer voice coil weighs around a 1/4 lb (like a good hamburger), and a tweeter voice coil weighs about half a gram. Less than the tracking force of a cartridge on vinyl, and clearly unable to dissipate more than a few watts. This implies that full power from an amplifier at 20 kHz is not needed at all, and all who have seriously designed and listened to amps have come to realize this sooner or later. And of course the folks who designed our RIAA and vinyl system did so long ago. Still, power response is different from frequency response; since our human hearing mechanism normally extends from 23 Hz to 22kHz, and our threshold of feeling curve crosses the threshold of hearing curve at 23 Hz (in a normal human being of average physical dimensions capable of lifting big tube amps), we do need to go that low. Beyond that, 22 kHz is the normal upper limit for an eighteen year-old who has not been in a rock band. For the rest of us, we must have the music a few dB louder in order to get above our hearing threshold at 22 kHz. Thanks for asking a great question! Bob Carver
Q:  Do you have any other amplifiers for sale? Thanks Dec-29-08
A:  Hi Mark '98, I don't have any more tube amps that I built, but I DO have lots of vintage tube amps designed by the Masters of time long ago. I may put some up for auction in the near future; I wish I had some ready to go right now for you, but I do not. Keep in touch. bob.sunfire@gmail.com Thanks for writing, Bob Carver
Q:  All I can say is "Holy-Wa"! Someday my fortunes will change..... Beautiful! Thanks for showing these! Rod KB8DNS Dec-28-08
A:  Hi Rod 'DNS, I assume "Holy-Wa" is almost the same as HOLY MOLY ROLLERS! Like Captain Marvel (Billy Batson) used to say. Did you know DNS means "do not stuff" when appended to a schematic; it means the designer doesn't know if she or he wants the part installed or not. Happy new year! There is no doubt in my mind at all that your fortunes will change; they always do every day. Thanks for writing, Bob Carver
Q:  Good Evening Bob, I Just wanted to tell you that I enjoy and am getting an education just reading the "Question and Answer" part of your e-bay auction, I enjoy it very much. The best of luck on this sale and I will say "Happy New Year" and prosperous 2009 Bob Carver. Best Regards, Jay Fletcher Dec-28-08
A:  Hi Jay, Thanks for taking the time to write, for I've enjoyed being a teacher once again, and I'm glad you are enjoying the Q&A part as well. Thanks again for wishing the best of luck. Happy new year, best wishes and a great year! Bob Carver
Q:  HI AGAIN YOU LOOK GREAT .THE MOST TRUSTED MAN ON EBAY. ...AGAIN THE BEST TO YOU ,HAPPY NEW YEAR FROM BRUCE AND CARLA FOREVERMUSIC414 BALTO MD Dec-28-08
A:  Hi again 'music 414 Carla and Bruce, It's my big straw hat that makes me look good(?). Must be..... Happy New Year and all my best, Bob Carver
Q:  Can you send it to Beijing? Thanks Kobemin Dec-28-08
A:  Hi 'min, We do possess the technology to send it to Beijing. Actually it's not me, rather it's Boeing, Airbus, United Shipping, Far East landing Co. and many others including UPS or Fed Ex. Not to mention at least two governments. So the answer is yes, we can send it to Beijing. Bob Carver
Q:  Can we get " Tubular Joe" to sign off too??? I have so much Carver stuff it's embarrassing!! Will you help me with set up if I win??? Thank you so much for your everything!!!! Dec-27-08
A:  Hi 'king, You bet, all three of us! If you live close by, I'll come over to your home and help. If you are far away, I'll still help, but we'll do it by phone, e-mail and lots of talking. I sort of understand embarrassment, as I have too have lots of Citation amps, preamps and tuners. Best wishes and lots of luck, Bob Carver
Q:  Does this work in 220v or do I need an adapter? If I need an adapter, would something like this work? http://www.110220volts.com/ATVR-1000.html Thanks a lot. Dec-25-08
A:  Hi '871, This amp can be wired for 220 volts or you can use an adaptor,either way. The ATVR-1000 will work great;one unit will power both amps. Good question, thanks for asking. Bob Carver
Q:  Hello Bob, Good to see you. I am still listening to your Phase linear Model 2000 series II, and Model 200 series II amp and preamp. Since parts are hard to get and they are 30 years old, any chance for you to come up with new circuit for their chassis to keep these fine vintage equipment going? Thanks, Joe Dec-25-08
A:  Hi '123, No problem and no worries. Rita helm, the best fix-it true lady in all the land, has recently started a service shop to do just that. She has worked for me for over 20(!) years repairing and updating vintage Phase, Carver, and Sunfire equipment. She's famous! Send it to: Rita's Vintage Audio Service, 1920 Bickford Ave, Snohomish, WA 98290. Or call her at 425 530 9557 good luck and thanks for writing, Bob Carver.
Q:  Hello Bob Carver, Mr. Carver I did not know at the time that I started writing to you that man you are a LEGEND and I am not "Blowing Smoke" </:-) Merry Christmas Bob!!! Jay Fletcher Dec-24-08
A:  Thanks Jay, Merry Christmas to you as well! WOW! Your icon really does look like Santa. I'm going to try it. </:-) Oh well, for some reason my letters spaced themselves out too far. I tried. Pehaps the letters will space correctly when I push the "send" button. Cheers, Bob Carver
Q:  I'm interested in learning more. I have built a state of the art sound room in NYC it's first class/ better than any dealers and I am moving this hobby towards becoming a business. I am currently a dealer for Wadia digital, ATC speakers, Analysis speakers, sme tone arms, ortofon products. I had a very bad experience with a Japanese solid state amp builder (technical brain). I've come running back to tubes. I've been into rolling tubes in other equipment I own and am stunned by the magic I'm hearing. I really liked the story behind your products and would like to explore more. Can you build a similar more powerful Amp? The sound room speakers the largest and best of speaker companies. Please advise... Bill Dec-24-08
A:  Hi Bill '005, I for one cannot imagine a business more rewarding than audio. Lots of hard work of course and bumps along the way, just the same, NOTHING is more fun. There is no doubt in my mind but that your efforts will be super successful. And yes, I can build a similar and more powerful tube amp. An easy walk in the park, only problem is I would have to rob my museum to get all the vintage parts, or search the world for new ones, or make them myself (output transformers). If you have some pics, I'd love to see them. bob.sunfire@gmail.com Thanks writing, Bob Carver
Q:  Hi there Bob - I saw your posting for the new amp - good to know you are still around and doing TUBES - in my collection I have 2 Citation I's and 2's - Do you contribute any forums, websites, discussion groups ? I would love to find out more about the DC fix you mention - Gary Boyd Dec-24-08
A:  Hi Gary 'lues, I don't, but it's never too late, right? I had lunch with Stu Hegeman (the designer of the Citation equipment) around the time he came out with his HAPPY 1 preamp, and left that long and extended lunch meeting with many of his ideas and thoughts burned into my brain. What a genius he was! He showed me several important up-dates for Citation 2's, and I will be happy to share them with you if you contact me after the auction. That goes for my own DC restorer as well; I've put it into every Citation tube amp I own, along with Stu's up-dates. Anybody else want the information, just contact me as well after the auction. bob.sunfire@gmail.com Thanks for writing, Bob Carver
Q:  My gosh, that's great! Keep up the good work. Hope you make plenty money and keep making amps. Best regards, Ray Harvey Dec-23-08
A:  Hi Ray '1919, Thanks for the nice thought and for the enthusiastic cheer. I'll always make amps; couldn't stop even if I wanted to. As I've often said - Bob's my name and amps are my game. Hey Ray, you can be my friend forever! Bob Carver
Q:  Hello, Bob. It has to have been close to 35 years since I attended one of your gatherings (in NYC, though for the life of me, I can't think where . . . Harvey, Lyric or Liberty, perhaps?) It is great to see what you've been up to and you have certainly piqued my curiosity. Is there a third amp available (the Citation has a center channel out, I believe)? And, as a side issue, can the ceramic input on the Citation be modified to a moving coil section? I had the I and II back in the day mated to Altec A-7s,then to some speakers of my own design. I always admired the Citations. The pre-amp was a particular favourite. Currently, these would drive EV TRX-15s in restored Karlson cabinets . . . if I decide to do it, of course. Everyone's business, including mine, is tapering off. Great to see your enthusiasm is still so strong! Dec-22-08
A:  Hi '46 Bob, I can't remember either - probably Lyric with Mike Kay. Oh well, at least I do remember the gathering, and yes the ceramic input can be modified for MC. A walk in the park! And I've done it already. And it retains the Hegeman phono-stage magic. If you bid and win, and would like this update, no problem at all. Happy to do it. I have wonderful memories of working in Seattle Stereo Center where we carried TRX-15's, but not in Karlson cabinets. Hey, we are in the arena with no early out. One last thing, these are mono blocks, so an odd one (three)is easy. Thanks for writing, Bob Carver
Q:  HI Bob, I'll throw in my two cents since I have first hand knowledge. Sorry I havent gotten back to you on the amp points we discussed but Ive been running different pre-amps and Speaker combo's hoping to settle on one and then get back to you but I gotta tell you, These things are like a Ritz Cracker, Everything tastes great on them. I ran one of your old C19's into it as well as a Marantz C45 and a really sweet Linn. Ive been looking for some tube pre's to audition and now you decide to offer a Citation also! Well, to let everyone know, all I can say is these are truly amazing and worth every penny I paid, and then some. I think I might stop by the repair shop next time Im in that neighborhood. Arent you in Cahoots with a repair shop there? However, I'll get back to you. Have a Great Holiday and Thanks Again!! Dec-21-08
A:  Hi again '217, Good to hear from you, and glad you like the amp and think it's truly amazing! - you made my day! Really have. Ritz Cracker huh? I always thought more like a chocolate covered peanut butter cookie. You have a great holiday too, thanks for writing. Bob Carver
Q:  Choosing Iron and Winding Transformers. Cont...? Dec-21-08
A:  Hi 'blondies, Since these massive and expensive transformers were wound during the Golden Era for tube amplifiers, they were wound on the best core that money could buy at the time. However it was tough for designers of the time to get both low frequency core saturation and high frequency leakage inductance to vanishingly small values simultaneously, as these properties are almost mutually exclusive. Back then even the best transformer steel("iron")was not nearly as good as it is today, and in order to obtain the best performance, various artful winding methods were used to get it right. The way they did it was to wind many, many sections, interdigitated, interleaved and cross-wound while all the time insuring minimum leakage through the use of bifilar nesting of the wires inside the transformer. It became a true art form mastered only by a few. Today we can count all the great vintage output transformers on one hand alone. And they are and were EXPENSIVE! Today we have much better steel (though copper wire has not changed much),and different winding methods have evolved to take advantage of the new steel. A simple two or four interleave is the normal way it's done today. Dirt cheap by comparison. I think I loved my transformers more than my girlfriend when I was in college, and I don't know what I'm going to do when I run out. I have my old transformer winding machine; perhaps I'll just copy these using the vintage winding methods but with modern steel. I'm not out yet, if I can only find them. Fascinating question, thanks for asking.
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This one is a repeat of the first posting in this thread, except having come from the original auction pages each entry is date stamped like the others above and that's the only reason I post it here.
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Question & Answer Answered On
Q:  Hi Bob, redstone7 here again from Colorado Springs, I have to ask one more question......is there ever going to be a tube preamplifier offered from your camp right here on E-Bay??? Thanks much, Rob Mar-21-09
A:  Hi Rob'stone7, not from me ( I should never say never), but James Sauter IS planning to build an exact copy of the preamp I designed for the Silver Sevens long ago. He may be found on the Carver Fest forum. Thanks again, Bob Carver
Q:  continued,, so now there is being fed to the bias pot a filtered neg. DC, that is decoupled from the filter capacitors, that can change with without the lag that a capacitor would cause. It must have been pretty darn fast because I could hook the amp to a scope,set idle to 15ma. suddenly zap a sinewave to it big enough to drive right up to just before clipping, and the sine wave would instantly appear with out gradually climbing up with flattened tops. That was good enough for me!!!!! I have bailed out of tube equipment, am now making chip amps from the latest audio grade offering from National Semiconductor.. they sound very "tubelike" to me (and many others) Just in time because I am getting too old to manhandle heavy iron. nevertheless I still maintain a keen interest in new ideas in tube technology. I would love to see a schematic of these amps..could you send me one to my email? The 6al5 is a high perveance duo diode.I'm trying to imagine how it is implemented..Neal Mar-21-09
A:  Hi Neal, I would be happy to send you a schematic....just e-mail me after the auction to remaind me. Don't forget to include your e-mail! Bob
Q:  Greetings Bob, I have followed you since the Silver 7, and Tim since the EAR, and I can not think of any other two who have added so much good music to the world. In fact reading of the Silver 7 is what got me interested in tubes...again (built my first tube amp in '57 with bits and pieces of discards, but cost drove me to transistors in 65 and cheap speakers masked the difference). Might it be possible for you to come up with a "kit" or built bias 'controller' that would be adaptable to different amps. I have a Meas Baron tri-tube modified which I love, but 1 bias and 1 balance pot to control 6 tubes per side requires frequent tweeking even though I use current matched tubes. It seems there is much interest in a better bias method. I have seen this in questions for the amps you have offered, and in many of the DYI groups as well. Many not be exciting to do, but it is a much needed product, and important tweek for tube amps. I you'd be swamped with sales too cordially, bud Mar-21-09
A:  Hi 'greg, I too have a pair of vintage Mesa Barons with six 6L6's per mono block amp. Beautiful amps! The 6AL5 DC restorer is the answer to your problem, plus it will stop the DC bounce that inevitably creeps into the system as the grid bias "hunts" under dynamic conditions. E-mail me after the auction and I'll send you the complete fix and the schematic as I used in my Baron. Warmest and best, Bob Carver
Q:  Hi Bob...thank you for responding to my confusion concerning your bias scheme,,but first I want to say to the bidders:....BID AWAY, BOYS AND GIRLS.I HAVE INDEPENDENTLY DUPLICATED THE ESSENTAL FEATURES AND CAN ASSURE YOU THIS IS THE ONLY WAY TO OPTIMIZE FOR AUDIO QUALITY AND LONGEVITY. SO BID WITH ASSURANCE MORTGAGE YOUR HOME IF YOU CAN GET ONE OR EVEN HAVE A JOB LEFT TO THINK ABOUT IT Ok I think I know where my confusion lies----when I say sliding bias I mean changing the G1 negative voltage....when you say sliding bias you refer to a particular TECHNIQUE to change G1 neg. volt. Consider the neg source half or full wave, there will be a smoothing cap followed by a an RC tage ,followe by maybe another RC smoothing stage..Now follow with a resistor voltage divider WITH NO CAPACITOR ..the center connection now feeds the bias pot..One leg of the volt divider is paralleled with a device that changes resistance with input drive....continued Mar-21-09
A:  Not exactly, but close enough for Gov'nt work. Keep that brain going 1000 RPM and we can have a scientific discussion about bias off-line. Bob
Q:  dear Bob....thank you for hanging in there with my audio-amatuer forays into mysteries of tube amps. I don't understand your bias stablization...it doesn't jive with your comments which I quote here "the dc restorer eliminated the need to idle each output tube at 50 watts yielding instead an idle power of 12 watts per tube....It works by keeping the dc componant on each output tube grid the exact value throgh the entire audio signal swing allowing perfect performance up to and even beyond clipping" Well, if by dc componant you refer to the negative bias grid voltage this is exactly how I describe my sliding bias scheme. If your bias scheme doen't shift the negative bias as the amp moves away from idle it will soon run into class B operation and really gross distortion. Your previous response says the bias doesn't slide , but if by slide we mean changing the bias voltage , then it MUST slide to my way of thinking...I'm confused cordially neal Mar-21-09
A:  Hi '541, ....It jives perfectly with my comments. A sliding bias scheme has too much delay in responding under dynamic conditions OR it has too much control voltage ripple modulation for my taste. Such a scheme must ALWAYS be a compromise between the two. That's because it will have a detector diode, an integrating capacitor, and a time constant comprised of the final smoothing RC filter. The topology is often similar to a meter drive circuit. On the other hand, a DC restorer operates such that the DC value of the waveform on the grid remains where we want it even in the presence of asymmetrical, haversine signals. And its delay time is essentially zero because there is no filter capacitor to charge and therefore no time constant. Works far better, and is far more elegant than a simple and coarse sliding bias circuit. Bob Carver
Q:  Bob....Come on..Bob..don't you want to explain to the prospective buyers the magic trick of 12 watts idle ( 18ma. at 660 volts anode) per output tube and not slide the bias to lower and lower negative G1 volts under progressively greater dynamic conditions to keep out of class B operation and unlistenable distortion?? ("My dc restorer is not a sliding bias approach, rather its purpose is to keep the DC value on the control grid at design center etc etc" your words , not mine) we are all waiting with breathless anticipation cordially Neal in Oregon Mar-21-09
A:  Continued next following.
Q:  Hi Bob, can you say a bit more about how this amp sounds? Can you elaborate on "the sound: This amplifier stands with a small handful of the world's great vacuum tube amplifiers" a bit more, especially sound-wise, which of the great amplifiers are most similar to your amp? Thank you, Frank Mar-21-09
A:  Hi '211k, I would say my own Silver Seven's, my Subsequent Silver Sevens with extra output tubes and dual screen regulators. (Two 6550's per amp.) The $30,000 Manley amps, and the Mesa Barons at 150 watts. I've limited this to vintage amps. Hope it helps, Bob Carver
Q:  ...which output tubes are used in this amp, 6550's or the kt88's, the write up refers to both articles tim depravacini/stu hegeman and yourself, is there any difference between the carver/pravacini mono's and carver/hegeman mono amps? thank you! david Mar-21-09
A:  Hey old friend, these amps use KT88's. The difference is in the front end; these use 12AT7's, 12AX7's, and 6AL5's with KT88's. The Hegeman units use 6AW8's, 12BH7's, and 6AL5's with 6550's. I cannot answer the question which one do I like better because it's just like asking which of your children do you love more. I love them both the same, even though they each possess distinctive audio personalities! Bob Carver
Q:  What an honour to be able to ask you a question,Bob. How do you think these amps would match up with Apogee Duetta Signatures' current and voltage loads, and would you recommend running both MT ribbons and bass panels with them ? (Trying to get away from present biamping with chip amps on bass and tube hybrids on MT ribbon and into a more coherent one-amp sound, if that makes sense). Your vintage pair here have come up on the Apogee users' website as one possible ultimate amp for Apogees, which would be wonderful for one who, like me, is just looking for that final and permanent piece of his system. Mar-21-09
A:  Hi 'fitte, I prefer the one-amp coherent sound unless the amplifier is not powerful enough to avoid clipping and overload on some of your music. This amp has been designed to run the Apogee Scintilla one ohm speaker....I really worked hard to get it to do that. So it should be a walk-in-the-park for the Duetta. The power increases as the impedance decreases....up to 300 watts, just what the Apogee needs and loves. I would not bi-amp here, perhaps bi-wire with heavy gauge for the bass panels and finer wire for the ribbons. Try it both ways. Bob Carver
Q:  Hello Bob, I was reading your writings here and you mentioned that your friend Stu liked the 6550's better than the KT-88's but I see you opted for the 88's on this design,is there a specific reason because of the overall design or is it more about personal preference? The funding is not here to bid on your current effort but I'm right in the middle of re-tubing my MC-275's and your input would be greatly appreciated , Thanks, Rob McRae in Colorado Springs Mar-20-09
A:  Hi 'stone 7, Remember that Stu was designing tube amps long ago and the KT88 was very new on our shores. At the time, the mighty 6550 was supreme, was considered the best and the finest, and was used by all the great designers back then. However, the KT88 was on its way. I love both tubes and would be happy with either, but I have a giant stash of NOS vintage KT88's to use from my museum. Bob
Q:  Hello Mr. Carver, is there any comparison between these beauties and the legendary Silver series of tube amps you created long ago ?? Could they realistically be produced again, given the growing high-end audio gear market, especially in the tube sector ? Since I was unable to attend CarverFest last year, I'm still hoping to view the Q&A session that was recorded , I submitted questions for you and have yet to learn what your answers were ! Maybe this year !!! Respectfully yours, silver7t1 Mar-20-09
A:  Hi '7t1, Oh no! I never got your questions, or perhaps I did and have forgotten. Try again at bob.sunfire@gmail.com., The relationship between the two amplifier designs is what I call crystalized knowledge. The Silver Sevens are similalar to the 520 circuit, whereas these have the cicuit described above. You bet this year! Bob Carver
Q:  Hello Bob I consider it a honor to even ASK you a question, let alone receive an answer!LOL Anyways I'm wondering about the transformers, can you disclose what they are for primary Z? Also I don't see a choke in your PSU, is it CRC filtered then? Thanks WOT Mar-20-09
A:  Hi 'tour, I have hooked them up to match four output tubes, so in this design, since I have six of them they are intentionally underloaded which allows them to operate such that an easy 180 watts is obtained, and is the reason the output power can increase when havily loaded with a difficult to drive speaker load. All CRC filtering, and with so much that a vintage designer woul find it difficult to believe.
Q:  Bob - Oops, forgot that the text mentioned the bias control. I am fascinated by the driver. It looks like a 12AX7 sized T-6 tube, short envelope. I would be interested in finding out what it is. Again, it looks like a 5687. Tim Smith Mar-19-09
A:  It's a 12AT7 double mica, military frame grid NOS tube and can easily drive three outputs per plate with a 33,000 ohm resistor following. See the RCA tube manual. Excellent question. Bob
Q:  Bob- Will you ever decide to release this tube amp design for production commercially? Mar-19-09
A:  Hi '1, I would love to but that would take more vintage parts than I have to spare. I don't know what I'll do when I run out of output transformers, but I'll think of somthing....maybe I'll just clone a Partridge or something, as I still have my old transformer winding machine.Warmest and best, Bob Carver
Q:  Hey Bob---just let 'rama know he can find me by going to my eBay page. He can go to the site map, click on find members, and put in tubular_joe. Thanks! Mar-19-09
A:  Got it! Bob
Q:  Bob - Magnificent amps! A few questions but don't the feel the need to answer if you'd be compromising proprietary information. It looks like the KT88 grids are fed from the 6AL5 cathodes - can't tell, the chassis photo is grainy. Also, are all of the KT88s controlled by a single bias pot (rear of amp?) or does your circuitry handle bias needs - can't tell if there's a bias pot at the rear. Is the driver tube a 5687? That strikes as about the only small tube (non-Russian) that would have the ability to drive a sextet of KT88s. I've built amps for several years, essentially all with regulated pentode output stages; think they sound the best. I recently finished a 45 watt/channel rig that uses Russian 6P41S vertical amp tubes run at 460 on the plates and 185 on the screens, If you're interested I can send photos; email address is tim.e.smith@bhpbilliton.com. Good luck selling these, I hope they find a good home. Thanks, Tim Smith Mar-19-09
A:  This is going to be a fast answer...I'm on a two minute time-out computer. The drive comes from a 12AT7. The 6AL5 IS connected to the grids to control the D.C. All the output tubes are cintrolled by a single pot, not for balance so much as for the ability to trim the soundstage envelopment. And yes I would love to see see photoes.
Q:  It is a pleasure and a privilege to view your tube amp and to read your Q&A. You are truly a designer for the people, reminiscent of when you took the Stereophile challenge and made affordable gear sound like reference. Sorry for the off topic question but I am dying to know if there is a postscript to the challenge. Cheers! Mar-19-09
A:  Hi 'it, Well, the only postscript that comes to mind is that after all these years, the original article is still being posted around the world in several languages and many forums. It suprises me to this day that a single article by J. Gordon Holt has had so much staying power. Thank you for writing, Bob Carver
Q:  Dear Bob, Another thought I have is concerning your comment that only four types of circiut designs for tube amps have ever been invented. With your design being a 5th circuit, would it have been possible to design this circuit 50 years ago with the type of componets available at the time or would you have had to add a bunch more tubes and circuits to accomplish the same design 50 years ago. Am I making any sense? Thank you again, Frank E. Mar-19-09
A:  Hi Frank, What a great question. sinc`e this amp is built of vintage parts, it would absolutely have been possible 50 years ago. Even the 6AL5 was around back then. But neither Tim nor I were. And yes, you make a lot of sense! Bob Carver
Q:  Dear Bob, I have a quick question, for my own information. I like the look of your pots. Are they a pot and or transformer combo that you made. My only guess is maybe McIntosh?? And if your quad wiring and DC Restorer are available to look at on a schematic. ( if your pats. are secure and filed of course). I am not going to copy it at all, just interested, of course! Thanks again, Frank E. Mar-19-09
A:  Hi '632, I don't remember where I got the pots....it was so long ago. Remember, I was old when Atlantas sank! I'll send you a schematic if you remind me after the auction, and you are welcome to copy it to build an amp if you wish. Thanks for writing, Bob Carver
Q:  Hi Bob How many dB of Global Feedback do you use in these amps? Is the feedback on the secondary of the OPT? Mar-19-09
A:  Hi 'Plies, Our amp uses the classical amount of 20 dB and if the output transformer is good enough to support a full twenty dB a switch on the front can change it to 11 db, a contemporary amount often used by modern amplifier designers. I prefer 20 dB. I prefer the full twenty if the output transformer is good enough to support it.
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Rodney, thanks for posting those.  It actually brings tears to my eyes to read about so many audiophiles reacting to Bob's OBVIOUS love of this field!
 
 I'm hoping these pages are preserved for all to see for many years to come.  Having met Bob last year at CF '08, I feel like one of the luckiest folks on the planet.  I am SO HAPPY I got the opportunity to attend last year; too bad about this year.

ANY of you who can jump in the car & make to even a DAY of CarverFest '09 need to do it!!!

 

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Question & Answer Answered On
Q:  What about the picture of the rear panel? Oct-27-09
A:  Well, I tried my best to get it up, but the help lady for eBay said that since I already had twelve pictures, I was stuck. So.....I'll use words. The back panel has a gold RCA input jack, two fuses, one for AC and one for the tube cathodes, a beefy line cord (see photo), a power switch, a flush mounted bias adjustment, four big terminal binding posts for the speaker, one black, three red, one ohm, four ohms, eight ohms. The back panel color is red, same as the rest of the chassis. Hope this helps, Bob Carver
Q:  Hi Bob, Lasareath here from the Polk Audio Forum. The Amps look so nice! Do you have any pictures of the rear panel? Thanks!!! Oct-27-09
A:  Hi Lasareath, yes I do; I just forgot to put it up with the other pictures. I'll see if I can add it at this late date - give me a couple of hours from now and check again. It's a great shot. Thanks for the reminder, and keep your fingers crossed that I can add it. Bob Carver
Q:  Bob, what preamplifier would you suggest for your amp? Oct-27-09
A:  Hi '871, I have several favorite vacuum tube preamplifiers, including the ones I designed. Just the same, for this discussion never mind those. Ahh, but for classic vintage tube units, my favorites are the Stu Hegeman designed Citation I, and the Tim de Paravicini designed EAR. Tim's has a beautiful as well as the quietest MC phono stage in the world, and Stu's masterpiece has wonderful tone controls and a spectacular sounding MM phono stage. If you have a moving coil cartridge and one of Tim's MC transformers, I would mate it with the Citation I and live forever in audio Heaven. Otherwise I would choose the EAR. When I was in hi-school, I had a job at a local Hi-Fidelity store called Seattle Radio Supply. We carried McIntosh, Marantz, Fisher, Scott, Citation, JBL and several others as well. I was allowed to take home as many as I wished, try them out and report my findings back to my boss. It was during that summer that I developed my preferences, and since EAR did not yet exist, my favorites became, in order, Citation, JBL, Marantz, Fisher, McIntosh. I was very young of course, but with all those superb units, I was truly able to stand on the shoulders of giants. Hope this helps, Bob Carver
Q:  Hello Mr. Carver. Is it possible to have these amplifiers converted over to 240v? If so, what would the cost be? Thank you for your time, Fritz Oct-25-09
A:  Hi Fritz, The cost is free, and yes it is possible. No problem at all, and the best part is that it can be done here in my laboratory or by you (assuming you know how to solder with a soldering iron). Or by a qualified technician. Good question, thanks for asking - ummm, I think I already answered this question. Oh well, twice never hurts. Warmest and best, Bob Carver
Q:  Hi Bob this is Eddie from Carverfest! I have to say you outdid yourself on this pair Bob they look sweet and I know they will sound as great too! Best wishes Eddie! Oct-25-09
A:  Hi Eddie! Thanks for the thumbs up - I found some vintage meters on eBay and a new paint color extremely close to the metallic burgundy cherry red I have had in my head for all these years. Thank all you guys for doing Carverfest - I sure had a ball. Bob Carver
Q:  Hi,,Do you ship t6o Thailand? Oct-23-09
A:  Hi '97. Yes I have the technology to ship these to Thailand. However I get help from Boeing, Airbus, and Overseas shipping inc. And of course the customs folks. Cost would be $516 dollars for both amplifiers. Hope this helps, Bob Carver
Q:  Hi, Bob. Do you build single end class A integrated amp with EL156/KT88/6550 (240VAC) compatible? How much would it cost with shipping to Singapore? Best regards John Oct-22-09
A:  Hi John. I don't specifically build a single ended unit, however this amplifier may easily be configured for single ended class A operation if desired. And with six KT88's, it would be the most majestic of all SE amplifiers! If you join the bidding and win my auction, I would be happy to make the conversion for you special. Of course you would still need a separate preamp. As for shipping and to Singapore, it would be $256 dollars for each amp. Hope this helps. Best wishes and warmest regards, Bob Carver.
Q:  Hello Bob, I just had to write and say "your amps just keep looking better", cool meters!!!, I like them. The best to you, "jay" Oct-21-09
A:  Hi Jay. Thanks for the accolade - helps make my day. I like the meters too - I found a stash of these vintage meters on eBay and thought WOW!would they ever look cool on a cherry red amplifier. Glad you agree. Bob
Q:  1st off I would like to say hello, and that it is really great seeing you getting back into tube amplifiers again. My first question: Is it possible to have these amplifiers wired for 240v if I were to win them? Second: would you mind explaining how your DC Restorer works please? Thank you for your time, and I look forward to hearing back from you. Warmest regards, Fritz Oct-21-09
A:  Hi Fritz. Yes, the unit can be wired for 240 volts - it has a dual winding power transformer for that purpose. It's a standard and easily made changeover. As for the DC restorer, first a bit of history: A class AB amplifier works by having the positive part of the waveform amplified by the top output tube, and the negative part by the bottom tube. In the case of a sine wave, the positive part is half a sine wave, or HAVERSINE, and similarly for the negative half. During the hand-off from positive HAVERSINE to negative HAVERSINE, that is, during the crossover period, the amplifier operates in class A. For the rest of the time it operates in class B - hence AB. Now the top tubes deliver a half sine wave signal to the output transformer, and this half sine wave possesses a DC value which depends on its amplitude. For lowest distortion, the drive signal on its grid should be a mirror image of the transformer drive signal and possess a corresponding DC value. It should be an identical haversine, differing only by the gain of the tube. And the two signals should be in perfect synchronism. Normal practise is to drive the grid with a standard sine wave that is symmetrical about the zero axis, so its DC value is zero. The DC restorer clamps the bottom half of the grid drive signal, thereby imparting a DC value to the grid and simultaneously providing a mirror image of the plate signal. The result is that both plate and grid have corresponding DC values. The best part is that idle power is cut to about one third, distortion to about one third, and finally, NO DC shift! The old way required enormous (by my standards) idle power in order to overcome or minimize these problems, never properly fixed the problems anyway, and has vexed designers since the very beginning. Often the output tubes were idled right at their maximum possible power rating, or even slightly beyond, often glowing cherry red. They got too hot, and didn't last long. WHEW! I hope you're still awake! Bob.
Q:  How in the world do you get over 300 watts out of such a small tube amp ??? Oct-20-09
A:  Hi 'i-o, Small? Small! It's big! I just knew someone would ask that, and here is the answer. This amplifier uses the mighty Silver Eagle KT88, and each pair is rated for 110 watts of audio output. Since the output stage is comprised of six tubes, we have 3 X 110 = 330 watts! Beyond possessing the raw power, the output transformer must have the correct turns ratio to deliver it all. The equal windings on this transformer allow a perfect match to either one or two ohms. And the mighty Silver Eagles do the rest. Great question, thanks for asking. Bob Carver
Q:  Can you ship to Italy? How much cost? Thanks Carlo Oct-20-09
A:  Hi Carlo, Yes indeed I can ship to Italy - I have the technology to do it - actually Boeing and Airbus do, and the cost is approximately $280.00. Thanks for asking and good luck.
Q:  Hello! For what sum are ready to sell at once? Best Regards Oct-20-09
A: 
Hello Nem'08, No amount, as we want this auction to run its clock down. Thanks for asking though, and if you join the bidding, I'll honestly root for you. Warmest and best regards, Bob Carver.
 
The above was from Bob's metered amps sold on 10/30/09

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Reading through all of this makes me darn proud of my Carver addiction.  all the high-falutin' knobs who sneer at my "mid-fi aspirations" for old Carver/Sunfire rigs should have copies of the above interviews stapled to their foreheads.   happy0009.gif

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What follows below is the Q&A section of Bob's tube amp auction that ended 12/13/09.  One of the questions contains a web address that Firefox flags as possibly hosting malware or is a forged site.  I suggest exercising caution should you wish to access that address.
 
The final sale price was $6975
 
Question & Answer Answered On
Q:  hi I am very interested in bidding on the amplifiers. How ever I wanted to check to make sure to would be okay to submit payment on wednesday......Pending I win the auction please let me know Thanks Robin Dec-13-09
A:  Hi Robin, No problem, no worries. Wednesday or even Thursday would be just fine. Hope this helps, Bob Carver
Q:  Hi Bob, I am currently am running B&W 800Ds with Audio Research REF5 and LAMM M1.2s REFs... How would this work in my setup (in place of the LAMMs)? Dec-13-09
A:  Hi '3xud, I'm assuming you're running your Lamm M1.2 on the bottom and your AR on top. If that's the case, then you have 120 solid state watts for the bass frequencies. More power would almost certainly give you better bass. Here's what I would try as an experiment (to find out). Temporarily reverse your amps with tubes on bottom and transistors on top. This will allow you to hear the characteristics of a tube amp with its impedance tracking ability for the low end. You won't be able to play it very loud, but that's okay for this experiment. Pay attention to the CHARACTER of the bass, and read my other answer below for a scientific discussion regarding the advantages of tube amps for bass PROVIDING (!) they possess high current drive capability. Bottom line - no pun intended - is that these amps would be better for your low end than the Lamm. And I could be wrong. Hope this helps, Bob Carver.
Q:  I was ready to bid on your auction, when a friend showed me this forum: http://ws1.chitose.melsa.net.id/phpMyAdmin/config/community/eBayShowBlog/ People say bad things about you. Are you an honest seller? Dec-13-09
A:  Hi '1987, I tried to get to that forum, but could not - probably because I pushed a wrong button somewhere. Anyway, I'm sort of used to people saying bad things about me, even though I try to be a powerful force for good in our audio world. Oh well, at least there are lots who say good things about me; way more than the bad stuff, fortunately balancing the bad stuff all out. If I took it in, I'd drive myself crazy. So I just remember the good stuff and stay sane. And yes, I'm an honest seller; I'll even fix my amp free as long as I'm alive, even if it means replacing all the tubes. An easy promise - the chances of that are almost zero - everything would have to break all at once! If you want to test if it's really me here, ask me a question that only I would know the answer to. Like my dog's last name. See, it's really me! Warmest and best regards, Bob Carver
Q:  Dear Bob, sorry for asking question which is not regarding the current amp you are selling. :) I have your solid state Carver Research Lightstar Reference power amp from 1994. As there are several probs with the device, I want to ask if you could kindly send me a service manual. I could pay via paypal or any other option you would prefer. Many thanks in advance! Kind regards, Max (+7 495) 518-1870 Dec-13-09
A:  Hi Max, I would be happy to send you a schematic. I tried calling your number but could not reach you. Call Rita's at 425 530 9557, ask for Rita or Lisa, and I'll ask her to send you one. Also please send them your e-mail address. No charge, the schematic is free. Hope this helps, Bob Carver
Q:  Hi Bob, Ed again, I currently run a pair of Thiel CS5is through a pair of Krell KAS 2 class A mono blocks and am just wonder if your amps would be able give it the tube soundstage without sacrificing the bottom end? Thanks. Dec-13-09
A:  Hi Ed, For a variety of technical reasons, tube amps are able to deliver a beautiful and enveloping soundstage like no other. They also will have a bottom end that's more powerful than a solid state amp IF - and here's the caveat - they ALSO have a lot of current drive capability. Now, all cone based loudspeakers (including your Thiel's), have an impedance rise in the bottom end, and a tube amplifier can easily follow this rise because of its internal generator none-zero output impedance. A transistor amp usually has an internal generator impedance that approaches zero, so its drive can't follow that impedance rise. So far so good. But what goes wrong with all this in the real world is that tube amps almost always becomes current starved when trying to deliver intense low bass. That's where solid-state amps have an advantage, usually outweighing the intrinsic bass superiority of tube amps. The only way I know of to have my cake and eat it too ( besides forgetting some of the lessons my mother taught me), is to design a tube amp that has enormous current reserves. I did it on purpose with this amp by using twelve mighty KT88's in the output section, by operating their screen (grid #2) connections from a separate high voltage power source, and finally, by use of a DC restorer. This amp can deliver over 24 amperes and 300 watts into one ohm. With speech and music waveforms, that number becomes a whopping 450 watts into FOUR ohms with all the current we could rationally want. Better than all but the biggest solid state amps. Have your cake and eat it too - tube amp soundstage with low frequency bottom end impact and slam. Great question, Bob Carver
Q:  Hi Bob –Its straylight, I bought the 4th pair amps in Dec 2008, item #180315426456 including Citation I preamp that you rewired to create a moving coil input for me! -one of a kind! Bob, shortly after our last call I was diagnosed with a life threatening disease and although my prospects for surgery in January look good there are no guaranties in this life. It also makes having listened to your 180 mono amps over the past year all the more special. Your amps have been a true inspiration to me and your auctions are the best educational tool on ebay! After you and I leave the ‘stage of life’ your amps will go on to inspire a whole new generation to say "what a wonderful soundstage", "what was Bob thinking when he designed these?" Since we may never know exactly it only depends the mystery & charm of these wonderous audio creations -the best I've ever heard in a lifetime! Thnks for bringing these amps into the world...it has helped me focus on what's important in the remainder of my life Dec-12-09
A:  Hi Straylight - Your focus on the important things is going to last a long, long time to come; there are no early outs for you or for me. Not yet. You'll see. I'm calling you after January so I can watch over you and thank you from the bottom of my heart for your inspiring message! Bob
Q:  Mr. Carver...I am listening at this very moment to a Carver 390t tube CD player, and an M400a 'cube' running a pair of Maggie MG1c's....and LOVING THE SOUND! I've been a fan since acquiring the M400's a few years ago. I need though to get enough juice for a pair of MG3a's and I previously used a pair of the M400a's bridged to mono but soundstage collapsed beyond my tastes when bridged. ***Will your new amps have similar characteristics?*** The Maggies reveal everything and need plenty of power. 500wpc is not TOO much if it's clean. Dec-11-09
A:  Hi 'st, Oh man, you are making my day! It's fun to hear about your M400 still making music after all these years! As for these 180's, since they are tube amps and have an output transformer with taps that will step up their output voltage, bridging them would be redundant and unnecessary. Regarding their soundstage presentation - that's one of the things big tube amps do best, building a soundstage, and with beautiful imaging inside that big soundstage. Great comments, thanks for writing. Bob Carver
Q:  Hello Bob Could you email me the dimensions of the amps please as i have two amp stands and would like to know if your amps would fit them. Could these amps be picked in person as i live in Vancouver B.C. Thank-you Ken Dec-10-09
A:  Hi Ken, 12 1/4" wide X 14" deep X 7" high. Plus the height of the feet = 0.5". Plus the terminals on the back stick out ~ 0.8". I spent my first year in grad school at the UBC right there in Vancouver, and have many fond memories of my time there. I'll go you one better - I would love to drive around my old campus from so long ago, so if you win our auction, I'll deliver them myself, help set them up, take you to dinner and talk into the night about tube amps. Thanks for writing, Bob Carver
Q:  Hi Mr. Carver, It's both a pleasure and an honor. I wish I had a disposable income at this point that enabled me to snap up this last pair of amps, but I do not - short of winning the lottery :) Have you made any progress in cloning those unique transformers, or is this the last pair of amps that will feature these wonderful characteristics? Of course, I ask because I am also an Apogee owner that wants a tube amp that can "deliver the goods" with whatever Apogee model I choose. I have owned Scintillas, but sold them due to economic considerations, and now own a pair of hybrid Centaurs. Thanks for your time. rube Dec-10-09
A:  Hi Rube, Oh well, maybe you WILL win the lottery, or the Irish Sweepstakes - I'll be keeping my fingers crossed. As for output transformer progress, I've been too busy of late to start the project as clonemaster for these transformers, but I will start soon. The biggest Apogees were the most difficult to drive, and I must commend Jason Bloom for designing them HIS way for the best possible sound, allowing the impedance to fall wherever it needed to be to get the perfection he wanted. That takes a great deal of courage in the face of practical issues, such as getting the speaker to work with normal amplifiers. I too am an Apogee lover - that's exactly why I had to make this tube amp operate into one ohm. Thanks for writing, Bob Carver
Q:  Hello Mr Carver! Beautiful amps! And I have three different pairs of Apogees, among thme the Scintillas; that that I’m sure would love to be powered by these babies. I am however a european resident. Can they be rewired for 220V? Can you ship to Europe? Best regards, J Dec-10-09
A:  These amps do LOVE Scintillas, and they can easily be wired for 220V, as they have a split primary designed just for that purpose. And yes, I can ship to Europe by using technology from the Cross Oceanic Shipping company, Boeing, or Airbus. Bob Carver.
Q:  Hi Bob, Are these only wired for 110v only? Does the transformer allow for a 220/240v tap? Thanks Regards Ed Dec-10-09
A:  Hi Ed, The power transformer has a split primary, allowing it to be wired for 110/120 or 220/240. The changeover is easily done by you, me, or a qualified technician. Thanks for asking, Bob Carver
Q:  Hello Mr. Carver, it's a pleasure to see another one of your beautiful amps. Would you be so kind as to email me a pic of the rear and a schematic? I don't want to assume all the large brown caps are coupling caps. Viewing the minimalistic design, I feel like a curious kitten. I'd also like to know the dimensions. In regards to specs, I've had input impedance issues with a Cary product that resulted in poor input sensitivity. What would you recommend for these amps? My tube preamp specs are Gain= 18.5db, Output Impedance= 40 ohms, and Max output= 40vrms. Hopefully my preamp will like these amps, and I'll be warming up my music room and spinning my vinyl with these. Looking forward to your answers. Best Regards, Werner. Dec-09-09
A:  Hi 'samx, I would be happy to send you a picture and a schematic. I need your e-mail address; please send it to me bob.sunfire@gmail.com On another note, the input impedance of this amp is 100K ,and its gain is 30dB. That means it is perfect for your preamp, as the loss would be 0.0035 dB - nothing! And with 18.5 dB gain from your preamp, you will have all the drive you could ever hope to have. Thanks for the questions, Bob Carver
Q:  Are you using a negative feedback to stabilize the DC? I notice you have this in some nice wood chassis or maybe it is metal. I found this stuff called MuMetal. It is expensive, but I use it in high end guitars and amps for use on the stage where lighting and other stuff wreaks havoc with EMF and 60 Hz hum. I would really like to know how you have balanced the DC on this. What did you use as output transformers? Are they old vintage or custom wound? I find some of the older stuff is not consistent. Key word is SOME. 1 ohm tap!?!?! I see that very rarely, and not usually on tube amps. The sound through a 1 ohm speaker(s) is very detailed and sweet. I wound guitar pickups custom on both a couple home made hand machines, lead screw guided machines, and the famous Leesona (POS). I am looking into financing a CNC cutter for core laminates and a Chinese made CNC lead screw machine that supposedly will handle up to #6 AWG. I am super curious. Contact me. God bless you 2! Dec-09-09
A:  Hi 'moeddie again, Since this tube amp has an output transformer, and all its feedback is taken from the secondary winding, there can be no DC feedback. That's because a DC signal cannot be supported at all by a transformer. It would have to be infinite in size - that's bigger than the universe is large - 15 billion light years to its visible edge. Though this output transformer is massive, it's not quite that massive! The output transformers are very vintage, not custom wound, and each possesses a split bifilar wound secondary. Hence the one ohm tap, which emerges quite naturally by wiring the secondary half up, half down. Viola' - one ohm and 305 watts, thanks to the DC restorer and six KT88's. As for Mu-Metal, it's great stuff, expensive as you said, and normally restricted to very small amounts where low level signals need to be well shielded - as in guitar and vinyl phono pickups. Hope this helps, Bob Carver
Q:  I do work for a man who owns a used car dealership that deals in high end cars. They are status symbols but they go down in value faster that they can go down the road. He has a small museum of old guitars and amps in an old courthouse in upstate NY. I do lots of repairs and try like anything to use Astron caps, or whatever was original, or just use good stuff and keep the old parts (always keep the old parts in a bag). I would like more information on how you stabilize the DC from drift and shift as I call it. Either it is drifting around, or sometimes it will just shift from a reference point suddenly. My utility power quality is perhaps the worst in any large urban setting. We had 62 MPH top wind gust at 23:07 Mon night. The top recorded was 74 MPH. 250,000 people lost power. I have had 83 interruptions since 21:30 Mon. There are spikes, sag, noise, and even freq drift of >10%. I run through a UPS and iso trans just so I can work. I'd love more info on this. Dec-09-09
A:  Hi Satchmo, Well, I hope these amps don't go down in value as they get older. I hope they become classics down the road and GROW in value because they sound great, as well as becoming (in time) vintage. Now that I think about it, they already are vintage because of all the vintage parts inside. The DC shift is eliminated through the use of several things: one, about ten times more energy storage than vintage classics used, two, balanced long-tailed voltage amplifiers from the input stage through the output stage, and three, the use of a 6AL5 DC restorer to restore the lost DC value of the signal as it propagates from input to output. These three things combine to reduce idle power dissipation, harmonic and IM distortion, and best of all, "drift and shift". With this amp you won't need a UPS and an isolation transformer at all! Bob Carver
Q:  Any pictures of the rear panel of the unit??? Regards, Warren Galliano Dec-09-09
A:  Hi 'ianno, I DO have a nice picture of the rear panel, but I don't know how to post it here without starting my auction over. That's because I already have the picture limit posted, according to the eBay help line. Looks as if I goofed up at the start of this auction. What's your e-mail address and I'll e-mail the picture to you. Bob Carver
Q:  Hi Bob, I spoke with you last year about your new amp design. You had offered to shoot me some information on the design schematics. I never had a chance to follow up with you and I lost track of your ebay name. I have built a couple of amps this year based on the Williamson design using KT66's with 6CG7 drivers and Heathkit iron. Not a bad sound at all to them! I would love to get a look at your new amp circuits if it is still Ok with you. Thank you for helping me out if you can! Frank Erdin New Jersey Dec-09-09
A:  Hi Frank, There is nothing more fun than building tube amps, and the Williamson circuit is a true classic that would bring lots of pride in a personal home built unit. I'd be glad to e-mail you a schematic, just give me your e-mail address and I'll send it off to you this evening. Bob Carver
Q:  Hi Bob, can you tell us a little about your Scintilla speakers? Original ribbons? Modifications? Did you own other Apogees as well? Thanks from a former Carver amp/preamp owner from the past as well as a current Scintilla owner. Dec-09-09
A:  Hi 'ale, I bought them many years ago from a Carver dealer here in Seattle. They are the original ribbons, with no modifications, and yes, I owned several other smaller Apogees around the same time as I owned these. I can clearly remember thinking - "I am truly in the presence of a great loudspeaker, maybe even the greatest." - when I first listened to the Scintilla. On another note, I hope your Carver amp found a happy home, even if it's no longer driving Apogees. Bob Carver
Q:  There's always more transformers somewhere and fabulous things to design! Dec-09-09
A:  Absolutely! But sometimes with a hitch. I bought these output transformers long ago when I was a freshman in college from a surplus place in Los Angeles. I've finally gotten around to looking inside one of them - my last one - and it is built way to expensively and beautifully to be a commercial transformer; it is clearly a military spec transformer, probably built in a time when output transformer design was far more artful than it is today. There is none that can compare, as far as I know, and I'm not exaggerating. As I see it, my job now is to figure out how it was built in every detail. Then I can clone it. Bob Carver
Q:  Hello Bob Thought I would use this way to say g'day to an unlikely Ap' owner as I don't have an email address for you! That valve amp looks FANTASTIC!! Bet it could solve a few of my clients "problems" ;) Take care - Graz info@apogeeacoustics.com Dec-09-09
A:  Hello Graz, Thanks for the accolades. I think they look great too, but then again I designed 'em so I was prejudiced to start with. Still, I must say they operate my Apogees beautifully; it's that one ohm tap and the six mighty KT88's. My e-mail is bob.sunfire@gmail.com Bob Carver
Q:  how many pairs have you made and how many more can you make like these , these look so nice BOB , good job ,very classy thanks kevin Dec-09-09
A:  Hi '739, I have not kept track all that well, however I think five pairs to date and auctioned on eBay. I'm out of these great output transformers now(except for one lone unit), so I cannot build any more amplifiers like these unless I clone the transformers. However I do have my old transformer winding machine left over from my Silver Seven days, and if I get lucky enough I'll be able to use it and make a close facsimile. Thanks for the appreciation Kevin, it took me some time to find just the right color - it came from an old '56 Chevy I had as a teenager. Metallic strawberry burgundy. Bob Carver

Q:  Hi Bob, How would these compare with silver 7's? Dec-07-09
A:  Hi 'rc, That's like asking "Who do you love the most?" I love them all - each has a distinct and different personality, unique and beautiful, but different. Children and amplifiers share SOME things in common. My Silver 7's are not to be believed, they are so good. - I didn't say it - many others did though, and these new mono- block amps are designed with Tim's and my latest thinking. I love them both!
Q:  Good Morning Bob, I'll change my name to Skip if you want to send those "Babies" to Oklahoma, serously tho, the new color scheme and the meters make me want to stand up and take notice, you have another winning pair there. "jay" Dec-07-09
A:  Hi 'music, If you changed your name to Skip, the amps might just skip right past Oklahoma on their way to audio Nirvana somewhere beyond Beethoven's 9th. But then again, perhaps not. Bob Carver
Q:  Wow! Sounds like some real schmoes out there just using your photos and such. Knowing Ebay I bet they do little about it. Dang! Dec-04-09
A:  Hi 'tube meister, It's extremely frustrating - I have tried repeatedly to put an end to it but found it impossible so far. In all fairness to eBay, I don't think they can do much either. So I'm left with posting WARNINGS wherever I can. If any reader knows of anyone being cheated by this fraudulent offer, please let me know right here on the eBay forum. If it occurs in this country, I have a good chance of stopping it and probably even getting the victim's money back. Bob Carver
 
 
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This is a little bit out of sequence unless Rich can re-order the posts in this list.  The following is the Q&A from the second pair of amps sold.  Of particular note is these are the Stu Hegemam/Bob Carver design and have slightly different specs.  Dates for this posting can be found at the end of each question.  I do not know if this was the entire Q&A because sometimes they ran into 2 or more pages and this is not a direct HTML copy, but it belongs here for posterity anyway.   It was generously posted in the Dark Tower by the owner.  Now, if only we could find the Q&A from the very first auction........
 
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Q: Hi Bob, I am also like many others having really hard time believing that it is you. Anyways, my question to you is are you also planning on building matching new tube preamps to go along with these? Please let me know. Thanks, Jul-02-08
A: It's me alright. And no, I don't have plans to make a new tube preamp. A Sunfire or Citation I preamp would do nicely though. Good question! Bob Carver
Q: Hi Bob, Can you please indicate the input options and the input impedence. Also the sensitivity input voltage for full output. The damping factor at 4 ohms speaker load. THD and IMD at full output. Thanks, James Jul-02-08
A: Since gain = 30 dB,sensitivity for 205 watts @8 ohms = 1.28 volts. My favorite Zout = 0.425 @ 4 ohms,yielding a damping factor of 9.41, THD = 0.15%, IMD = 0.5%, Zin = 100,000 ohms. Since this is a basic amp, input options are limited only by our imaginations. Bob Carver
Q: Dear Bob, Are you are the man who designed the phase linear amps? I want your amps but living in Hong Kong, can I have chance to buy it? many thanks, Alex Jun-30-08
A: Hi Alex, Yes, I am the one who designed the Phase Linear amplifiers. And yes, of course you have a chance to buy it. Warmest and best regards, Bob Carver
Q: Hello Bob; Other than to clean your closet, why is Bob Carver, one of this generations great audio designers, selling onesies (single units)? Thank you! Jun-30-08
A: I really don't know why. It's just that whenever I look at my lifetime collection of vintage parts, I feel like building an amplifier. I don't know why, I just do.
Q: Hey Bob. You forgot to mention the split primary on the power tranny. Also, what about the weight and power specs? Thanks, Joe Jun-29-08
A: Oops! I forgot. Correction: This amplifier is rated at 205 watts, not 180 watts. That's because the GE 6550's are remarkably efficient. The amps weigh more than 42 pounds each - 44 lbs each. And they possess 120/240 volts, 50/60 Hz AC line capability. I used some older text and failed to update. The remaining specs are accurate. Please accept my deepest apologies. Bob Carver
Q: Hi Bob, You just never know who you'll run into on eBay. How kool is this, the great Bob Carver, designer of audio equipment extrodinaire! One question Bob, does Bill Gates ever invite you over for a cookout or to play 18 holes? Take care and keep designing all that great audio equipment. Regards, Ted Moyer Jun-29-08
A: I wish, except I'd rather design amplifiers than play golf. Thanks Ted for the extraordinaire! You made my day! Bob Carver
Q: Dear Bob, Beautiful amps, again! I am very curious about your circuit -- Is this similar to a Citation V, or more like a Lafayette 550 with a triode plate follower to provide the inverted signal? Which video pentode (or pentode+triode?) has been used? Thanks! And, best of luck with the auction. Jun-29-08
A: This inverter is more like the Lafayette 550 anode follower. I like this inverter because it is immune to tube parameter shifts. In my opinion, The Lafayette 550 was his very best and most inspired work. Complex but brilliant. I'm using a 6AW8 video pentode plus triode. Thanks for your comments and for asking. Bob Carver
Q: I thought these were designed by Carver and DePavaracini? When did this change? Jun-28-08
A: These are completely different amplifiers. The ones designed by Tim and me were auctioned two weeks ago. I'm glad you asked because I think others may miss that point as well. Bob Carver
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The following is the Q&A from the third pair of  Bob's metered tube amps sold on 1/3/10 for $6600 on eBay.  Of note, these amps used a different transformer than did the previous amps, in this case Partridge transformers that were a gift from Julian Hirsch, and as such had a slightly lower output but are still able to drive a 1 ohm load.  I was amazed to see this sale jump from $4125 to the final price of $6600 in the last 90 seconds or so as I monitored the auction close.  Like all of eBay's Q&A pages the earlier questions begin at the bottom of this post.
 
Question & Answer Answered On
Q:  The CARVER CHALLENGE took place some time ago, before you designed the Sunfire amps, which I considered an improvement, but evidently, from what I understand here, even the best Sunfire amps don't have the sound of this tube amp, would that be a fair assessment? These two amps sure are sweet looking. And running the amps at low wattage dissipation, not pushing them, resulting in anywhere near a 50 year life span is an important advantage. Seems you have covered everything to make this superb ampliifer very desirable! Jan-03-10
A:  Yes.
Q:  Hi Bob, with a hour to go I am the highest bidder :) As for payment if I am the winner I do not think PayPal works at that high Dollar amount - What other payment would work for you? Fingers crossed I even get so far...THANKS!!! Dreams can come true! Jan-03-10
A:  Hi '500, No problem, no worries. I have my fingers crossed too. Any rational way you want to pay works fine for me. Keep on dreaming! It's good for our dreams. Bob Carver
Q:  That is a very interesting phenomenon regarding the speakers acting as microphones picking up ambiance! A real virtue for tube amps. I wonder if that signal could be accessed and fed to a solid state amp? Also, I recall that, in a demonstration years ago, that you were able to make a solid state amp sound so close to a tube amp that the listeners couldn't determine the difference. How did you manage to accomplish that feat? Jan-03-10
A:  Hi 100', I did come close! Read all about it! Google THE CARVER CHALLENGE or go to the Stereophile website or the Carverfest forum - the article has been reprinted a lot over the years. Bob Carver
Q:  Hello Bob, If you don't mind me asking, how do tube amplifiers make such a large sounding sound stage, that solid state amplifiers can't. Hope to hear back from you, Chris Jan-03-10
A:  Hi 'bdn, They do it by including the room in the musical presentation - the listening room becomes a significant part of the enveloping acoustic. Here's how it work: First, we need to understand that our human hearing mechanism "likes" to hear ambiance, echo, multiple arrivals arising from even a single sonic event. We like arrivals that are multiple, different in arrival times, and can tell us something about the musical "space", the place where the music was made. Now, all amplifiers have two inputs, one for the musical signal, and one for the feedback signal. These two inputs are called "potentiometric" and "inverting". When an amplifier makes a speaker speak, the sound leaves the speaker, travels to our ears, AND bounces off the walls of our listening room. In a tube amp, the bouncing sound arrives back at the speaker after a short round-trip delay and causes the speaker cone to move in response. It acts like a microphone, converting this energy into an electrical signal. Since the speaker is connected to the amplifier output, and the feedback loop is connected to the amplifier output, that "room signal" is fed back to the non-potentiometric input of the amplifier, is amplified once again (both signals are always essentially equal to one another), and appears as a voltage that drives the speaker again. In other words, the amplifier has "listened" for and "heard" the room, and the room's character is added to the amplifier output. By doing so, the amplifier and room become an important part of the total acoustic. Solid state amps can't do that at all because they short out the microphone/room signal. They are intrinsically voltage mode devices, not current mode devices like tubes; their low output impedance literally short circuits the microphone signal, preventing the room character from playing its part. There are other reasons, but they are beyond the scope of my missive here. By the way, ALL amplifiers have feedback, no matter what the advertising says! Bob
Q:  Hello! Ask this project, with what model Pre-amplifier optimum matching? Thanks! Jan-03-10
A:  hi'inshi, a nice vacuum tube preamp would be a great choice but not absolutely necessary. This amp is easy to drive, so almost any modern or vintage unit will work nicely. My all time favorite vintage preamp is Stewart Hegeman's Citation I, with a close second the Audio Research SP-3a. My own Sunfire tube preamp is not yet old enough to be vintage, and my Carver tube preamp designed for the Silver Seven tube amp is impossible to find today. Too rare. Thanks for writing and for asking, Bob Carver
Q:  Greetings Mr. Carver, How do you get so much power from a transformer that was designed to put out only 20 watts. Thanks for your time. Tim Jan-03-10
A:  Hi Tim, I just knew someone would ask that. Here is how it works: In the old days(The Partridge was designed around 1947), output transformer design was almost pure art until D.T.N.(Also known as A.N.) Williamson designed the Williamson amplifier and the output transformer for it. The winding geometry was new and unheard of for the time, resulting in almost magical(It wasn't really magic of course)performance not to be believed. What he did was specify that EACH section of the output winding be brought out of the core, accessible on the outside. Each transformer has 10 secondary windings that may be connected in parallel, series parallel, or in any combination that we desire. This allows a wide range of impedance matching configurations; all I had to do was hook them up to match the impedance of six KT88's. Williamson made my job easy - the impedance is related to the square of the turns ratio - so it was a simple matter to match eight ohms to six output tubes. And Viola', 130 watts. This transformer is massive, huge, and when I first held it in my hands I thought "All this for 20 watts?". Now I know why. He must have known I was coming in the future. Since this transformer used an amplifier with an unusually high voltage supply, the volt-time product as designed for the primary is about 38 volt-seconds, or perfect for this amp and 16 Hz! That's how. Hope I didn't put you to sleep! Bob Carver
Q:  Hi Bob. I have 1 question before placed bids: Those Golden Lion output tubes come with amps, are Reissued ? They don't look like NOS as mine, physically ! regards. Jan-02-10
A:  Hi'du, These Gold Lions are Mike Mathews's (Genelex's owner) masterpiece! They are that good. As far as I can tell, he has been trying for the last decade to build a great KT88/6550, and I for one must say he has succeeded in spades with this tube. I begin: Before I got some of these tubes to try, I did not know what to expect, and in truth was slightly suspicious of them. I have lots of the worlds great output tubes in my collection including Sylvania, GE, RCA, Genelex, Tung-Sol, as well as several of modern and recent manufacture. There are several important tests that show ultimate performance quality: Pull-down voltage(the ability to turn-on perfectly at maximum drive), maximum voltage swing into varying loads(the ability to drive difficult speakers and a measure of its power output vs load response), maximum possible output current, distortion (a measure of linearity), I could go on and on, but against ALL the parameters that I hold dear, Mike's masterpiece performed as follows: Pull-down, 48 volts (the lower the better), max current,0.68 amperes, linearity, 1.2%. Most of the other NOS tubes performed close to, if not quite equal to these. The most interesting comparison was the original British Genelex against these: Pull-down,48 volts, max current,0.68 amps, distortion, 1.3%. The sound? Well, that has as much to do with the circuit the tubes are used in - probably more - than the tube itself. Bottom line, these are great tubes equal in EVERY way to the original British versions. The only thing I can't know about is will they last 50 years? Here's hoping! Thanks for asking a super question, Bob Carver
Q:  Hi Bob, Beautiful amp, fine construction, great parts! Glad to hear you will build custom amps! No real hurry, but I've been thinking I would like a stereo tube amplifier with a bit more power, maybe using 8 KT88s (maybe 6550s would work, what do you think?) per channel, a good sized power supply sufficient to more than handle the draw without sagging. Probably have to be on three chassis. I would like it to be able to handle 2 ohm speaker impedance (for, as you mentioned, those speakers with difficult loads). Not having to replace tubes for anywhere near 50 years would be great, too! Jan-01-10
A:  Hi 'center, Bob's my name, and amps are my game!If you're looking for power, you've come to the right place! How much power are you thinking? Warmest, best and happy new year. Bob Carver Bob Carver
Q:  Hello again, I will be happy to e-mail some pictures to those that would like to see the finished product. Bob I will ever be grateful to you for your patience, understanding, your much needed expertise in building a pair of amps that are second to none and a dream come true. You have shown me that you are a man of your word and there is no doubt in my mind that what you say about your amps would be true and more. Best of Regards, "jay" Jan-01-10
A:  Hi Jay, Thanks again for the accolades. Bob Carver
Q:  Hello Bob, a year ago you promised to send me a schematic of the amps you were selling on E-bay you not only kept your promise to do that but you had upgraded it especially for me so I could use my Acrosound TO-330 output transformers and Genelex KT-88 Gold Lions tubes, you also spent one of your Sunday afternoons designing a special power section so I could use the big power transformers that I already had. Phone calls and many e-mails you guided me through the process of building the amps, and the results of this is a pair of amps that sounds stunning! Wow!!! The mid-range is like liquid honey, crystal highs that Memorex would love, lows you can feel deep in the soul, and the power output seems almost unlimited a sound that I can't stop listening to. I will be happy to e-mail some pictures to those that would like to see the finished product. to be continued in next question and answer, see below. Jan-01-10
A:  Hi Jay, It stirs my soul that you built it from my schematic and got it to work so well! glad you like the results, and I'm sure that building it was an awesome adventure. Warmest and best, Bob Carver.
Q:  Bob, One more question.... my preamp has balanced XLR output. Can the corresponding input be added to this amp ? Jan-01-10
A:  Hi '52 again, Others have asked about adding an XLR, and unfortunately the answer is no. Vintage gear has always used standard RCA inputs, and besides, I get great sound from these input configurations. I use it exclusively throughout my own system at home; There is ABSOLUTELY no advantage to XLR unless your system is picking up hum from a long cable run. Hope this helps '52ever, Bob Carver
Q:  Bob, You stated these amps have different tubes than the last set... Are they better , worse ? What is the difference? Also could you explain "Scintilla drive capable". Thanks One more ... would you consider making a pair on order rather than putting them up on eBay ? Sometimes the bidding can get out of hand. ( I know that is good for you) Thanks Again and Happy New Year Jan-01-10
A:  Hi 'ever, This amplifier pair has Gold Lion KT88's, whereas the the last amplifier had Silver Eagle KT88's. One set is not better than the other. Historically the Gold Lions were designed to go with the Partridge output transformers, and I optimized the Silver Eagles for my original output transformers. That's the main difference. Scintilla drive capable simply means the amps can drive one ohm, the impedance of the Scintilla loudspeaker. Since it was designed to drive one ohm with about 20% current to spare, it can also drive other difficult to operate speakers. As for making an amp to order - I need to ask Tubular Joe if he would consider building a set -I don't see why not, but for the moment these amps are e-Bay amps. Thanks for the two very interesting questions, Bob Carver
Q:  good morning Bob,just a short note,i spent a good part of iast night listening to my new amps,there a dream come true,didn't know what i was missing all these years.a slap on the back is due whoever packed them,traveled 3000 miles without a hitch,great job.your new amps sound promiseing,maybe i can make them mine also,maybe not we'll see,thanks again,Robin Dec-31-09
A:  Hi Robin, Wow! Thanks for letting me know how much you like them and for making my day. I bet when you won them last auction you never thought you might bid for these new ones this auction too. Thanks again, Bob Carver
Q:  Hello Bob, I know its you because you gave us your Dogs last name - And I know your Dog well! :) Question now: If I am the winner (I will try) Will you get a Picture of you signing them (Digital) and email it too me? Best Wishes & THANKS!!! Dec-30-09
A:  Yea '500gt! Bob Carver,
Q:  Hello Bob, I just wanted to state that I believe you should put your last name in the main heading of this listing. Not that I could afford these right now, but I did a search on Carver Amplifier and this was not in the listing. With your name in the listing I think you will get alot more views and maybe more bidding. I have one of your older amps that I love and I wish I could afford these beauties! Anyways good luck. tom Dec-30-09
A:  Hi '420, Thanks for your passion and thanks for writing. I know...... it's hard for me to figure out what to put in the main heading. Not enough room. Oh well, perhaps I'll try next time. Good idea, thanks again, Bob Carver
Q:  Hi Bob, Would these 130W amps make my Plats sound as good as the 180W amps you brought to the fest year before last, or do you think they would be a little light on power? Thanks, Skip Dec-30-09
A:  Hi '52 again, Well, for a variety of technical reasons, 130 watts of tube power is about the same as 200 watts of transistor amp power, so unless we are bugs-in-our-teeth crazy for SPL, I think these will play loud enough for normal, rational listening. It will be close though, as the Plats are only 96 db SPL per watt. Thanks, Bob Carver
Q:  The amps ending Dec. 13 also states that "the last pair" of Partridge transormers were used. Did you find more? I am local and would love to listen to them with the Scintillas. Any chance of an audition? Thanks. Dec-30-09
A:  Hi 'er, Not yet, and the ones that were Scintilla drive capable are no more. I'm trying to copy them, but so far without success.I would be delighted for you to come over for an audition with the Scintillas as soon I find a new transformer. Hope this helps, thanks for writing, Bob Carver
Q:  Hi Bob, Its me, Frank from Manahawkin NJ. Another nice beauty, Remember I had asked if you could send me a schematic of your new amp design, my email is ferdin@verizon.net I was also interested if you had given anymore thought to making your own OPT's. I thought your last amp was THE LAST, but I see you have another one. Or were you able to source opt from a manufactuer that will work with your design? I have been tweaking my newly built KT66 PP with 6cg7's and have improved it so much since its first trial that it will now out performs the McIntosh MC30's in power output and quality of sound performance. Especilly in the bass department. I have MC30's here at my house for the A/B test. Its the best Kt66 I have made so far. Now I want to do a stereo version on one single chassis. Well I dont want to take up anymore of your time. If you dont want me see the schematic, just tell me and I will stop bothering you, although I will still send you nice comments on your beautiful amps. Thanx Dec-30-09
A:  Hi 'frank, Thanks for sharing your Kt66 story. I'll trade you schematics. So far no luck in copying my earlier output transformers,but the future lies ahead and my effort is not over yet. Just kidding about the schematic trade, you don't need to send me yours, though I WOULD love to see it. I would be happy to e-mail you a copy, but you need to e-mail me after the auction so I will not forget. bob.sunfire@gmail.com
Q:  How would you characterize the frequency extension of these amps, bass impact and control, and treble? Also, I don't see a lot of capacitance compared to some other amps, can you comment on that? Thanks, Pete Dec-30-09
A:  Hi Pete, The impact, control, and extension stand side by side with the greats.Superb. As far as capacitance goes, this amp has about ten times more than any vintage amp I know of, with 700 joules of energy storage. Perhaps you meant driver capacitance, in which case the exact values are chosen for low-frequency loop-gain stability, and are related to the maximum volt-amp signal delivered to the primary of the output transformer. There is an optimum value for this,rather than "more is better"; the exact value is steeped in loop-gain and feedback theory. Hope I did not put you to sleep - great question, Bob Carver
Q:  Hi Bob, do you agree with Julian Hirsh that the Partridge transformers (in your new amplifiers), are arguably the best in the World? Thanks, Alain. Dec-29-09
A:  Hi Alain, They are absolutely ONE of the best in the world. No doubt about it! Their sound is ledgendary,they are wound like no other, and possess a power bandwidth that was,and still is to this day, a minor miracle. Thanks for writing, Bob Carve
 
Question & Answer Answered On
Q:  Hi Bob, do you agree with Julian Hirsh that the Partridge transformers (in your new amplifiers), are arguably the best in the World? Thanks, Alain. Dec-29-09
A:  Hi Alain, They are absolutely ONE of the best in the world. No doubt about it! Their sound is ledgendary,they are wound like no other, and possess a power bandwidth that was,and still is to this day, a minor miracle. Thanks for writing, Bob Carver
Q:  Sorry not about this item. Do you ever build 10 - 20 watt 300b sets? Dec-28-09
A:  Hi 'james, That's really a great question; it leads me to talk a bit about what I think is important in amplifier design. long ago, when amplifier design was in its infancy, designers were trying with all their might to eliminate both crossover and notch distortion in push-pull output stages. Success was almost impossible back then without resorting to impractical, heroic efforts. Single ended output stages were the only way that a practical output stage could be designed that was free of notch distortion. The problem was with the output transformer; something called leakage inductance caused a fly-back voltage to appear at its output,resulting in an aweful "snapping" sound for frequencies above about 3kHz. And so the class A,single ended output stage was born for everyman's amplifier. As time and history marched on, designers were able to eliminate the problem. Advanced winding methods and geometry, along with new steel for the magnetic circuit allowed a complete elimination of the problem to the point that today, push-pull circuits have far less distortion of all types than single ended ones can ever hope to have. That's not to say that single ended circuits can't sound wonderful and romantic with their sweet even order distortions - they do. But so can powerful push-pull designs. So.....I really don't like single ended amps, they just don't have enough power for me, and I have tried them over and over again. My amp has a switch that allows a reduction of feedback and an increase in the romantic distortion components for any of us who like it that way. The notch problem has somehow remained in our minds from the past, even though in reality modern transformer design has eliminated it. Good designs are totally free of it, and are smooth and linear with no trace at all of the old notch distortion! Thanks for writing, Bob Carver
Q:  Is this the same item that ended on Dec. 13th ? Dec-27-09
A:  Hi '52, Read on for the answer - but in a nutshell - no. Hope this helps - I probably should change the way I take the pictures, but I already have a little place I made for taking them. Someone once told me "If it's not broken, don't fix it." Thanks for writing, Bob Carver
Q:  Is this the same item that ended on Dec. 13th ? Dec-27-09
A:  Hi '52, Read on for the answer - but in a nutshell - no. Hope this helps - I probably should change the way I take the pictures, but I already have a little place I made for taking them. Someone once told me "If it's not broken, don't fix it." Thanks for writing, Bob Carver
Q:  Hello Bob! More of a statement than a question. I just wanted to thank you for your help in getting my Sunfire back to spec. I am happy to share with everyone here that when you promise to be there for someone if they ever need your assistance in fixing one of these amps that you are indeed a man of your word... Any plans of offering a matching preamp to go with these amps? How would you compare them to the legendary Carver Silver Seven Tube Monoblocks? Dec-27-09
A:  Hi 'ohn1, Thanks for your kind thoughts, and yes, I'll fix them free,even the tubes,as long as I'm alive. As for these amplifiers vs my Silver Sevens, that's like asking a parent which child he/ she loves the best. I love them both. Each amp has its own personality - each true, but each unique. So we see that children and tube amps have something in common. Thanks for writing, Bob Carver
Q:  Did I see this auction awhile back? Thanks! Dec-27-09
A:  Hi 'triump, Thise is the first time this auction has run - you probably saw one of our earlier auctions for amps that looked almost like these. The earlier amps all had Silver Eagle output tubes where these have Gold Lions, as well as Partridge output transformers.Hope this helps clarify, Bob Carver
Q:  Hi, How would I know this is real and not a scam ??? Do you have a buy it now price ? Dec-27-09
A:  hi '52ever, I know it can be hard sometimes to know a scam, even looking it in the face. Oh well, you can ask me a question for which only I would know the answer - like my dog's last name. Or a complex tube amplifier question. See, it's really me, Bob Carver
Q:  Beautiful amplifiers! Merry Christmas Bob Dec-26-09
A:  Hi 'soundz, Thank you. And merry Christmas tooo yoooo! And a happy,happy new year too. I'll answer all the other questions sent in after today. Warmest and best regards, Bob Carver
Q:  Hi Bob - I own some of your classic gear - Phase Linear 400 amp and SD/A-490t CD player. The PL carried a DJ biz I had while in college during the late '70s to early '80s. Question about these monoblocks: I notice similar (if not identical) components, yet this current set has a lower output specification from the prior example you auctioned. Will you please explain these apparent output differences? Thanks! --Scott. Dec-24-09
A:  Hi Scott, It makes me feel nice and warm inside that you remember, and actually own some of my classic gear after all these years. Yea! As for the power specification - it's related to the Partridge output transformer, which has a slightly different turns ratio (primary to secondary) than the output transformer I used on the other amps. Designing and winding output transformers is at least 40% art, with only the rest science. However back when the Partridge was invented by one A.N. Williamson(a true genius),it was probably 90% art. But even back then, the laws of compromises and trade-offs were the same as they are today. He traded maximum output power for a wider power response. A good trade? Perhaps. You decide. His results were superb, and he has gone down in history. Hope this helps, Bob Carver.
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Q:  Hello Bob' date=' If you don't mind me asking, how do tube amplifiers make such a large sounding sound stage, that solid state amplifiers can't. Hope to hear back from you, Chris Jan-03-10
A:  Hi 'bdn, They do it by including the room in the musical presentation - the listening room becomes a significant part of the enveloping acoustic. Here's how it work: First, we need to understand that our human hearing mechanism "likes" to hear ambiance, echo, multiple arrivals arising from even a single sonic event. We like arrivals that are multiple, different in arrival times, and can tell us something about the musical "space", the place where the music was made. Now, all amplifiers have two inputs, one for the musical signal, and one for the feedback signal. These two inputs are called "potentiometric" and "inverting". When an amplifier makes a speaker speak, the sound leaves the speaker, travels to our ears, AND bounces off the walls of our listening room. In a tube amp, the bouncing sound arrives back at the speaker after a short round-trip delay and causes the speaker cone to move in response. It acts like a microphone, converting this energy into an electrical signal. Since the speaker is connected to the amplifier output, and the feedback loop is connected to the amplifier output, that "room signal" is fed back to the non-potentiometric input of the amplifier, is amplified once again (both signals are always essentially equal to one another), and appears as a voltage that drives the speaker again. In other words, the amplifier has "listened" for and "heard" the room, and the room's character is added to the amplifier output. By doing so, the amplifier and room become an important part of the total acoustic. Solid state amps can't do that at all because they short out the microphone/room signal. They are intrinsically voltage mode devices, not current mode devices like tubes; their low output impedance literally short circuits the microphone signal, preventing the room character from playing its part. There are other reasons, but they are beyond the scope of my missive here. By the way, ALL amplifiers have feedback, no matter what the advertising says! Bob
[/quote']
 
Interesting; I'm currently reading Current-Driving of Loudspeakers: Remedy to the Fundamental Fallacy of Sound Reproduction Technology and it says almost the polar opposite:
 
Chapter 4: The crucial significance of the driving method, builds upon some of the principles and math described in earlier chapters, so I'll not re-type the whole book;
 
The meat of the math is that when driven by a constant current (vice constant voltage) amplifier, the back EMF generated by the voice coil (due to ALL sources) is ignored.  One of the sources of back EMF is, of course, the cone motion itself, but another source is microphonic coupling from the room.
 
Section 4.3 microphonic coupling, describes just such a scenario and demonstrates that current drive amplifiers aren't effected by it, but voltage drive amps are (albeit on the order of having to 'fight' an extra 2% induced back EMF)
 
In loudspeaker systems there is generated due to microphone coupling electromotive forces, which under voltage drive produce interference currents, roughly estimating, 40dB weaker than the actual signal.  Instead, under current drive, these detriments are avoidable because the total current of the drive units can then be kept accurate, irrespective of any microphone effects.

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If you look at his latest post he now states he is coming to CarverFest "WESTCOAST" eusa_dance.gif 

 


Q:  Hello Bob, Well this ones almost over and I just wanted to wish you Good Luck and hope this one brakes a new sales record on the price!!! Its worth it :) I hope to see you at the new West Coast Carverfest near Palm Springs Please come if you can! Still working on details though. No need to post this one public & I will watch this to the end - Again (GOOD LUCK)... Jan-29-10
A:  Hi '500gt, West Coast Carverfest! Of course I'll be there! Why am I always the last to find out about cool and important stuff? Never mind - don't answer that - it's a rhetorical question. When is it? Where is it in Palm Springs? I love Palm Springs - sounds like lots of fun. See you then and there. I'm posting this in case anyone else wants to come. Several hours to go, so I can post more information if you wish. Warmest and best, Bob Carver

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Here it is, the latest Q&A from the latest Carver tube amp auction which ended Saturday 1/30/10.  Of particular note is these are the first amps sold to have Bob's self-wound transformers.  It would appear these new transformers, wound to copy his original vintage military spec transformers, are actually capable of delivering more current but would require another pair of KT88 output tubes to take advantage of this.  That certainly makes me wonder if an 8 tube design is forthcoming.

 

Again, the way the auction page is built requires that you start at the bottom of this post and read upwards for chronological order.

 


Question & Answer Answered On

Q:  I think what you did in producing this amplifier surpasses anything that has ever been done before. Please think twice, or more, about not doing another. After all the advances with digital. I feel that there is a slow changing of the tide back to analog reproduction of music. There is no reason why we can't have both. Please, continue to produce a high end piece of audio equipment for those of us who appreciate it. Look at it in a different way. What if the Dead Sea Scrolls were written on digital media? Would we still be able to read it and with what program and hard ware? Hard copy is best and analog is the next best thing. Create a demand for it. Jan-29-10
A:  Hi 'earl, ".....surpasses anything that has ever been done before." Earl, your comment has brought me to my knees and it leaves me breathless. I am completely at a loss for words. Thank you. Bob Carver
Q:  Unbelievable you're personally replying to all these questions!!! Will you ever design a tube pre-amp? Especially one affordable to the common man? THANKS! Don Jan-29-10
A:  Hi Don, I don't think that for me to design a tube preamp - at least in the near future - is in the cards. But you never know. It turns out that my earlier vintage Sunfire tube preamp is now available from time to time here on eBay. It's used but it might as well be new as far as performance goes, and even if it isn't, I can fix it. There is nothing like a good preamp for sheer joy! Keep on listening and enjoy the music. Bob Carver.
Q:  Hello Bob, Well this ones almost over and I just wanted to wish you Good Luck and hope this one brakes a new sales record on the price!!! Its worth it :) I hope to see you at the new West Coast Carverfest near Palm Springs Please come if you can! Still working on details though. No need to post this one public & I will watch this to the end - Again (GOOD LUCK)... Jan-29-10
A:  Hi '500gt, West Coast Carverfest! Of course I'll be there! Why am I always the last to find out about cool and important stuff? Never mind - don't answer that - it's a rhetorical question. When is it? Where is it in Palm Springs? I love Palm Springs - sounds like lots of fun. See you then and there. I'm posting this in case anyone else wants to come. Several hours to go, so I can post more information if you wish. Warmest and best, Bob Carver
Q:  as a young soldier in the military 1986,i spent every hard earned dollar on carver equipment.matched input/output voltages with gains and rocked everyone in the theatre.only u.s. pieces and all of them mismatched and pushed to the limit of stock,mildly hot roddeed and all the way stuff we could get.an era of carver few who knew and yet wonder existed everyday. rock on! Jan-28-10
A:  Hi 'errs2, 1986 was a good time to be in the military, and it sounds like you enjoyed it immensely. If you were stationed at Fort Ord, near Carmel, California you were awakened each morn with a beautiful recording of reveille played through a Carver amp and piped to all those overhead speakers on top of high towers. Bet you didn't know that! Since I don't have a second thought on that, I'm stuck with the first. Just the same, I'm glad you wrote, and if you rock on, I'll rock on too. Warmest and best, Bob Carver
Q:  Hello Bob, I'll bet by now you are more than ready for this auction to end as surely that lovely amplifier is getting mighty heavy! It has been very enjoyable reading your gracious responses to such a long list of questions and for that reason I and many others will be sad for it coming to an end. I can not believe how approachable you seem to be and for that reason intend on keeping track of your contact information. I have recently sold the audio business I started 30 years ago and the cash flow benefits that went with it. Fortunately my tube and tube unit collection will keep me good company in my retirement. Your comments regarding your first glimpse of an mc275 are what I would have said to you given the opportunity. Sincere best wishes, Jody Varey, Ontario, Canada. Jan-28-10
A:  Hi Jody, Yes, I've been standing in the same spot for nine days holding that amplifier, but since it has magic it just gets lighter and lighter until it's going to float away with me holding on for dear life. I know what you mean about the auction coming to an end - it's sort of like closing the last page of a book and saying goodbye to all the wonderful characters. No goodbyes from me tonight though - I know how to wind great output transformers! Thanks for your thoughts, and I hope your retirement is as fruitful as you can imagine it. Bob Carver
Q:  For years I proudly showed off my Nikko Alpha 450 amp. After seeing this listing I am officially apologizing to anyone I mislead into believing that I knew what I was talking about. This unit is simply amazing! Now if I could just win the Lotto in the next 33 hours … Jan-28-10
A:  Hi 'leon3, I wish you good and hearty luck - lots of it. With my fingers crossed tight! Bob Carver
Q:  Hello, Thinking about bidding on the amps, but what preamp would you recommend with these units. Thanks, Brenda Jan-28-10
A:  Hi Brenda, My favorite preamp of all time is the Harmon Kardon Citation 1 preamp designed by an audio hero of mine, Stu Hegeman. If you can get one on eBay you will absolutely love it. If it does not work, I can fix it. Good luck Brenda, happy bidding. Bob Carver
Q:  Bob, You ssay that you have a switch for 2 feedback settings. How many db of feedback each and do you feel that feedback is truly sonically and, stability, wise necessary with these amps or is it simply to satisfy the measurements crowd. Having built and experimented extensively with tube amps I have heard the loss of space and hardening of sound that accompanies increasing feedback. It is not necessary to the sound performance of a well executed amplifier only to validate specication measurements. The comment from EE's that it's OK applied in moderation defies the reality that even that has a significant detrimental effect on music reproduction. Of course some of these guys think that 20db of feedback is "moderate" also while they try to band-aid the performance of their transformers and circuitry. Also, when you say "current source" does that mean that you are using a depletion mode mosfet at the end of a long tail? Thanks! Dan Devin PS. Tim is quite a character isn't he! Jan-28-10
A:  Hi Dan, The loss of space and hardening of sound you are experiencing is NOT the result of feedback or its lack thereof, rather it is a direct result of the way the feedback changes the amplifier characteristics. These characteristics may be designed into the amp and optimized through any number of ways, not just with feedback. If we remove all feedback, the internal resistance of the amplifier will be about twelve ohms or greater - that's too high. If the internal impedance is too low, the amp will short circuit the back-emf voltage from the speaker-room interaction and the system will sound dry and more or less like a flat curtain of sound strung, clothes-line style, between the speakers. If it is too high, the sound will be bloomy, swimmy, extra lush but with very poor focus and imaging. Listening this way can be fun for awhile but soon will make us want to get the "watery" feeling out of our ears. There is no absolute optimum internal resistance - it depends on our speaker, our room, and what's in our heads. Feedback is ONE way to modify these very audible characteristics. As for the long-tail, it's a 12AX7 with a resistor to minus voltage. And you are right - specifications are only part of a great sounding amplifier. AND no band-aids allowed! Bob Carver
Q:  Actually, this is not a question about this item; I apologize. I am a huge fan of yours and I have an all Carver 2 channel system at home which consists of the Sunfire Classic Preamp, Sunfire Amplifier (300w) and a pair of Carver Amazing Silver Edition Speakers. The only non Carver pieces are the sources (until you decide to make a turntable :) ). I cannot tell you how much I love this system, with the right recording it sends chills down my spine. There is only one problem; I am one of the unlucky few to have bought a used Classic Tube Preamp WITHOUT the phono stage. I have seen that you are selling these amplifiers here on ebay and I am wondering if there is a possibility that you might have one of those phono stage boards laying around that you would consider selling to me? If not I will just continue my search. Regardless, thank you for everything that you do for us music lovers! Anthony Jan-27-10
A:  Hi Anthony, Thanks for letting me know how much you are enjoying my designs, some long ago and some not so long ago - at least when measured in geologic time. As for the phono stage, I have three of them somewhere, but I need to look for them. In the meantime, please e-mail me, bob.sunfire@gmail.com and tell me if you use a moving magnet or moving coil cartridge. I'm looking forward to hearing from you, Bob Carver
Q:  HI Mr Carver..looks like the biding its going to be strong Do you have the info on value to ship to santiago chile ?? I need a figure to see how high will I go again thanks. Jan-26-10
A:  Hi '816, Yes, I just got it - expensive. US $262.00 for each amp, or US $524.00 for the pair. For that money, if you win and still live in Santiago, I'll ship four extra output tubes just in case. Warmest and best, Bob Carver
Q:  Hi Bob! I grew up sanding boxes in the back room of Speakerlab, and now am a student of Electronic Engineering in Tacoma. I love glass audio, and have always been a fan of your creations, but these amps of yours really are my favorite! The amps themselves are beautiful in design, but hand winding your own transformers puts you and them in a league of your own. To own a pair would be to own a work of great art. As a student, I can't currently afford these amps, but I want to know if you intend to continue to produce them. I would simply LOVE to own a pair, and would not hesitate to allocate a months wages...I saw the first pair go, and am watching the second pair go; Bob are you going to make more? How could I convince you that I'm worthy of a Schematic? Jan-25-10
A:  Hi 'dwell, If you grew up sanding cabinets at Speakerlab, you are definitely worthy of a schematic. As for winding the output transformers, I have to say it was originally David Hafler, the owner of Dynaco who taught me how to wind. I called him one late night in frustration because I could not get my prototype output transformer for the Silver Seven to work the way I wanted. He walked and talked me through it over the phone and when I finally - more or less - understood the science and the art, I asked how do I repay you for your time and graciousness? He said,"Bob, buy me a beer at the next CES show." I'm passing his generosity along; the schematic is yours. Go to the end of the auction and you will find a link to it. Thanks for writing, Bob Carver
Q:  Hi, Beautiful amps. Maybe I missed it but what are the dimensions? Also, I have a McIntosh MC275. Could you tell me what you think the differences in sound might be. Thanks, Boris Jan-25-10
A:  Hi Boris, 12 1/4" X 14 1/2" X 7 1/2" plus about an inch for the back panel connections. The McIntosh MC275 is an awesome amplifier, and is what started me in audio when one day long ago I rounded a corner and there in a store window was the most beautiful thing I had ever seen. Chrome, shiny black with form following function - a Mac 275. I was smitten! As for the sound - I designed this amp to deliver a large and lush soundstage with lots of power and headroom. Thanks for writing, Bob Carver
Q:  Hello Bob, Would you mind giving a brief explanation as to why solid state amplifiers tend to double their watts, as the impedance drops by half, as where tube amps are not rated in the same way? i.e.. A solid state amp that can put out 100watts at 8ohms, is usually rated 200watts 4ohms, and 400watts @ 2ohms. Why don't these tube amps to follow the same rule? This was taken from your last auction ((Power is an easy 180 watts rms with a power bandwidth from 23 Hz to 45 kHz, frequency response 2 Hz to 85 kHz, and distortion less than 0.15 % at 220 watts out. --- One Ohm Drive Capability: This amplifier has been designed with big Apogees in mind, the one ohm kind. It delivers 305 watts into my Apogee Scintilla – I included a one ohm tap on the output transformer.)) So why arn't we looking at 1440watts @ 1ohm? Thank you for any help you can offer in explaining this. Bill King / PA. Jan-25-10
A:  Hi Bill, Good question - here's my answer and I hope I don't put you and everyone to sleep. First, only the largest solid state amplifiers double their output power with every halving of load impedance. Most do increase, but not all that much. Solid state amps are very voltage limited, but normally possess an abundance of current. Tube amps are just the opposite - they have voltage that reaches for the sky, but are normally quite current limited. To get around that problem, tube amps have output taps for several load impedances, allowing full power to be delivered into any number of impedances. My solution is to use so many output tubes that lots of current and voltage can be be delivered at the same time. Each pair of KT88's is rated for 110 watts. So no matter how we slice or dice the power delivery, it cannot safely be more than 330 watts. No matter what the load impedance is. Having said all that, I arranged this design to allow the current to increase quite a bit with progressively increasing loads; the power increases even without changing taps, thanks to the mighty KT88's. However, at one ohm, the limit is reached and that's where the one ohm tap comes in. Wow! Whadda a question. Hope this helps, Bob Carver
Q:  Hi Mr Carver, from Santiago Chile I am the proud owner of tfm 35, mt 1/5 , hr 895 5.1) Months ago I listened my first tube amp ( audio research ) and decided I wanted one....I remember seen you on E-bay selling an amp...It caugth my atention because Im a fan of your work but was not ready to buy, yet.... Days ago, Martin Riesco a friend and Tim de Paravicini costumer let me heard a custom amp that Tim did for him, great.. Loved and did a google search of tim de paravicini and some how I found your ebay listing, unbelived no?? Its Like they are mind to me, very interested on your amps but have some question... Chile as 220v grid...a problem?? a 220v to 110 volt transformer Will do it ?? will you ship air freigth to Santiago Chile airport?? I guess I could send them to Miami but will be much easier to me if you could ship them to Chile..can you get a quotation?. I consider an Honor just to get in contact with you, Sir. Excuse my English best regards from down Jan-24-10
A:  Hi '816, What a small world it is. This amplifier has a split primary that may be easily wired for 240 or 120 volts. I designed it that way on purpose. And yes, I can ship to Chile or anywhere ships sail or Boeing or Airbus airplanes fly. After I post this I'll go to the Post Office site and get a quote. Look for it at the end of my answer to a following question. Warmest and best regards, Bob Carver
Q:  Hi Bob, You have a better track record with your transformer than Ben did with his bulb filament. Like the looks of that winder and the transformer that you made with it is amazing. Keep 'em coming. Best Regards, Jay Jan-24-10
A:  Hi 'music, Thanks, but I got rope (wire) burns until I put on the leather gloves. All was well after that, and I'm super happy that it turned out as well as it did. I have to admit I was worried for awhile. Thanks for your missive, Bob Carver
Q:  You mentioned in an answer to a previous question that "this amp is a tube amp; with speech and music it will sound more than half again as powerful as its rms rating." How can that be? Aren't Watts -> Watts, Volts -> Volts, etc.? Thanks. joe Jan-24-10
A:  Hi 'sram, Well, yes and no - it depends. A solid state amp cannot deliver more output voltage than its B+ and B- power supply. No matter what. But a vacuum tube amp can! A loudspeaker is a variable voltage source when it moves back and force; an engineer would say back-emf. A vacuum tube amplifier can easily track this back emf and deliver substantially more voltage to the loudspeaker voice coil whenever its back emf is relatively high. As an example, tonight Dave and I had a big eight ohm woofer on my laboratory bench and drove it with my eBay tube amp. The amp delivered 52.4 volts rms, whereas my solid state amp could only deliver 42 volts rms, yet the tube amp is rated for 180 watts and the solid state amp for 200 watts. Tube amp @52.4 volts = 343 watts, solid state amp @ 42 volts = 220 watts. That's why we often hear that tube amps are substantially more powerful than their rms rating - often one and a half times more powerful. In this example it was actually 1.9 times more! hope this helps. Great and interesting question, Bob Carver
Q:  Since these amplifiers are (obviously) a stereo pair of monoblocks, they each have their own dedicated power supply (and power cord). How much current does it take to drive them at full output? Will it overtax my power line mains? Should I have two separate (dedicated) circuits to run these? Beautiful looking amps, by the way, especially the retro-looking meters on the front panel. Thanks. Dave Jan-24-10
A:  Hi Dave, Wow! three at a time! Here goes: It won't overtax your power line mains one bit; the average input power is modest, and whenever a huge power transient comes along, the energy required is supplied from storage in the amp's power supply capacitor bank. They use less than four amps on average, a walk in the park for any normal wall outlet. No need to use separate circuits for all the above reasons. I'm glad you like the retro-meters - I found a nice stash of vintage meters on eBay and snagged them all. Thanks for writing, Bob Carver
Q:  Now that you have duplicated (and improved, it seems) the output transformer used in these amplifiers, are you planning on continuing with them? Thanks. Jan-24-10
A:  Hi 'amd, It's true I've "duplicated" the output transformers, but in reality I have not really improved them; they sound the same, exactly the same, as the vintage units I used in the earlier amplifiers. I used vintage wire, though that was not really important since elementary copper has not changed in the last 50 years, but I WAS forced to use modern steel. The new super-steel DID result in more power capability from the transformer, but in order to put that extra power use it I would have to add an extra pair of output tubes to the amplifier. The new transformer is everything I dreamed about or could possibly want, but without the extra tubes, it cannot deliver more power. Still, it's great to know I now have a totally over-designed output transformer, one that cannot possibly ever be a limiting factor. And yes, I absolutely plan on continuing with them. Great question, Bob Carver
Q:  Hi Mr. Carver! (Bob, if I may.) I mentioned in previous correspondence that I struggle with the technical language, concepts (etc.) that audio engineers must use to do what they do. Can you recommend a book that will help a layperson, such as myself, understand the technical side of audio design/engineering? Does such a book exist? I note that you have a real knack for parsing extremely complicated technical issues and making them accessible for non-technical audiophiles. A second, unrelated question. . . Can you remember how many Silver Seven Vacuum Tube Mono Power Amplifiers were built by Carver Corporation? Is it possible to buy a pre-owned Silver Seven? Do any new Silver Seven amps still exist? Is Carver still in business?? Any help you can provide would be greatly appreciated! I realize that even a pre-owned Silver Seven would be very expensive. Sincerely, Marc + Maria + beagles Vancouver, BC Email: fuzzymoose@telus.net Jan-23-10
A:  Hi Marc+Maria+puppies, Here goes one at a time: Thank you. We built about a hundred Silver Seven amps. Yes vintage Silver Sevens do appear on the market from time-to-time, and I know of a pair right now. They ARE expensive. New ones don't exist, that I know of, but that doesn't matter really, as these amps are so well cared for that they might as well be brand new. As for a book about audio, that depends. What technical level? Approximately. Let me know and I'll get back to you soon. Warmest and best, Bob Carver
Q:  A Marantz Model 9 amplifier (tube) was measured in a Boston Audio Society Amplifier Test Clinic. The results were spectacular. It outperformed most of the modern transistor amplifiers in the clinic. It was among the lowest in distortion and its frequency response into a simulated speaker load was flat. It ranked with the best in the clinic. Will your amplifier perform similarly? Jan-23-10
A:  Hello amf' again, Yes, but just to make certain I'll call Marantz and get back to you next week. Just kidding - read on. Excellent questions. Warmest and best regards, Bob Carver
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A:  Hello amf' again, Yes, but just to make certain I'll call Marantz and get back to you next week. Just kidding - read on. Excellent questions. Warmest and best regards, Bob Carver
 
Q:  Given the low power of the tube amplifier you are selling, what minimum speaker efficiency do you recommend? Jan-22-10
A:  Hi 'ail, low power?! This amp is a tube amp; with speech and music it will sound more than half again as powerful as its rms rating. That means it's almost 300 watts! The minimum speaker efficiency I would recommend depends on your listening taste. For reproducing wind chimes at realistic levels, I would say 72 dB SPL/one watt. For a full symphony orchestra, 86 dB. Hope this helps, Bob Carver.
Q:  I heard that good audio tubes were hard to find. What source do you suggest for replacement? Alvin Jan-22-10
A:  Hi Alvin, "Good tubes for audio are hard to find" is a false believe these days. There are many, many manufactures of excellent and wonderful tubes in existence. In addition, we can obtain great vintage tubes right here on eBay with a bit of looking. Bob Carver
Q:  Bob, Why do you prefer tube designs? Alvin Jan-22-10
A:  Hi Alvin, A deep and challenging question. It’s when we listen to them, some magic happens. Let me use as an example the soundstage as delivered by a tube amp, which generates a substantially larger acoustic space than a typical transistor amp. It does so by including the room in the musical presentation - the listening room becomes a significant part of the enveloping acoustic. First, we need to understand that our human hearing mechanism "likes" to hear ambiance; we like arrivals that are different in arrival times that can tell us something about the musical "space", where the music was made. Now, all amplifiers have two inputs, one for the musical signal, and one for the feedback signal. These two inputs are called "potentiometric" and "non-potentiometric”. As the amplifier makes the speaker speak, the sound leaves the speaker, travels to our ears, AND bounces off the walls of our listening room. In a tube amp, the bouncing sound arrives back at the speaker after a short round-trip delay and causes the speaker cone to move in response. It acts like a microphone, converting this energy into an electrical signal. The speaker is connected to the amplifier, and since the feedback loop is also connected to the amplifier, that "room signal" is fed back to the non-potentiometric input, is amplified once again, and appears as a voltage that drives the speaker once again as well. In other words, the amplifier has "listened" for and "heard" the room, and the room's character is added to the amplifier output. By doing so, the amplifier and room become an important part of the total acoustic. Solid state amps can't do that at all because their essentially zero output impedance shorts out the microphone/room signal, preventing the room character from playing its part. There are other reasons, but they are beyond the scope of my missive here. By the way, ALL amplifiers have feedback or its equivalent, no matter what the advertising says! Bob Carver
Q:  Hi Bob, I'm in Calgary, Alberta. I have two active home theatre Audio systems in my home that you designed (Sunfire amp/pre-amp and receiver). Very happy with both, now looking to upgrade my 2 channel system. I'm wondering if pickup is possible? I have a good friend in Mukilteo, close to you, and he might be willing to pickup and store until I can drive down to Washington. Thanks, Greg Jan-22-10
A:  Hi Greg, a pickup is indeed possible, and I would be delighted to load these amplifiers into your car. Or better yet, I'll deliver them to you, take you out to dinner, talk late into the night about audio, then troll around my old school, the UBC and relive wonderful old memories. Bob Carver
Q:  Hello Mr. Carver. I was currious to know what is the most difficult part of designing such a high powered tube amplifier? Thanks for your time. Chris Thomas - NY Jan-22-10
A:  Hi Chris, Oh Man! In 2000 characters or less, right? As Edison said, it's 1% inspiration and 99% perspiration. Designing the the first rough cut was pretty easy - all we did was draw the proposed circuit on a napkin, then we built it, and when it did not work, the real work started. There are several thousand refinements between that moment and the present amplifier, but the most (there are three) difficult design parameters to get right were the low and high frequancy compensation components. The last, and the part I spent by far the most time and effort on was getting the soundstage, the acoustic envelopement, and the imaging within that enveloping soundstage the way I wanted it. It was a man named Harry Pearson who first wrote about that long ago, and I remember being quite influenced by his teachings back then. Getting the soundstage right was the hardest. Hope I answered you question. Warmest and best, Bob Carver
Q:  Hello Bob, It's great ro see you still coming out with great new products. Do you have any plans for any other new (home brew) products any time soon? If so, what might they be? It's great to see a legends mind still hard at work. Kudos to you sir! Jan-22-10
A:  Hi 'o, Thank you for the kudos - that helps make my day. As far as more home brew - I don't know about right now, however I have always wanted to build a mind altering vacuum tube moving coil / moving magnet phono stage. Maybe later this year if Tubular Joe has the time to build one. I actually finished one 98% during my Carver days, but we never took it to market. All I would need to do is find the design and put in the finishing touches. Great question, thanks for asking, Bob Carver
Q:  Hi Bob! Preamble then question. Big fan in Canada (Vancouver). Consider this exchange to be a real honor. Like so many, have always admired the sheer ingenuity of your ideas & products. Now 100% B&O (I know, "Boo! Hiss!"; wife!), but I sure get nostalgic for the "good old days" when (your) Carver brand was, for me, the equivalent of the indelible yellow hot rod in "American Graffiti." Always vowed that I would get a proper pair of tube amps. . . one day. Remember positively drooling over a pair of Silver Seven tube monoblocks that came through Edmonton as part of a Carver marketing blitz (I was a student at U. of Alberta working part-time at National Music; early 90's). Question: Do you plan to manufacture/craft any more of these unique amps? Not sure what they should command; I am guessing a lot. Perhaps I should just monitor this auction. Best, Marc "Moose" Baragar + beagles PS Your passion for great audio design still puts me under a spell. Jan-21-10
A:  Hi Marc, Boy, do I remember that Vancouver trip well! It's as if it were yesterday, showing the Silver Seven to an audience of vacuum tube amplifier lovers, and with the University of British Columbia in the background. Speaking of which, I went to the U.B.C. when I started graduate school, and have great memories of Vancouver - a 90 minute drive from my own Snohomish, WA. As for building more amps, of course - Bob is my name and amps are my game. I couldn't stop buiding amplifiers even if I wanted to. Thanks Marc for a nice blast from the past. Warmest and best, Bob Carver
Q:  Hi Bob, "Hockey Jersey Tom" from Pittsburgh PA here. Great set of amps. I am the current high bidder and will try to score them. I have a off topic question for you. What should the bias be set at for a M-1.0t amp. I have one side running a bit hot. What test points do I use? GREAT job on Brian Turners amps!!! Thanks, Tom Zurcher Jan-20-10
A:  Hey Tom! High bidder! You are certainly passionate! Regarding the test points and the correct bias current, I don't know, but Rita does, plus I'll look it up tomorrow when I get to work. I need you to e-mail me with your e-mail adress so I won't forget, and I'm beyond glad to hear your M-1.0t is still working after all these years. I'm rooting for you. Warmest and best, Bob Carver
Q:  Any chance you'd share a schematic of your new creation? Strictly for a hobby project. It's very encouraging and motivating to see what you're doing!! Thanks, Pete Jan-20-10
A:  Hi Pete, I would love to share a schematic with you. Many have asked for a copy, so I'm going to post it on the Carver forum before this auction is over. If you want to go to the head of the line, send me a request at bob.sunfire@gmail.com along with your e-mail address and I'll send one. Hope this helps. Thanks for writing, Bob Carver
Q:  No question here, Bob; just wanted to tell you I admire what you've done & continue to do in furtherance of audio nirvana! Congratulations on your latest power transformer epiphany~ --TNRabbit from the Carver Forum Jan-20-10
A:  Thanks 'Rabbit, I'll tell you, I was a bit scared at first. Four unsuccessful tries before it finally worked had me thinking for a nano-second "What if I can't figure it out?". All's well that ends well. Bob Carver
Q:  Is the bidding for both of these FINE tube amps? Thanks, Best, Michael Jan-20-10
A:  Hi '1956, Absolutely yes. For both. I need to modify the auction to avoid confusion - I did not catch that when I listed it. Glad you asked and gave me the chance to clarify. Bob Carver

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Here's the Q & A from the latest tube amp auction that closed 4/11/10.  These amps would appear to be identical to the previous pair sporting a built-in meter and featuring Bob's self-wound transformers.  Incredibly these amps sold for    $10,099!  The auction price jumped from $7100 in the final 5 seconds!
 
Once again, you must start at the bottom of this post to read the Q&A in order.
 
Question & Answer Answered On
Q:  Greetings Mr. Carver, I just wanted to verify the shipping amount. The automatic pricing through eBay is telling me shipping the shipping cost is only $13.00. Can you please tell me if this amount is correct. I would expect the shipping for these beauties to be much higher. Thank you, Tom Apr-09-10
A:  Hi Tom, Oops! I goofed and did not catch it. That's a recent shipping amount for my vacuum tubes I sold about a week ago. The return is wrong too - (See below). Good catch! Thanks, Bob Carver
Q:  Hi Bob, Our fraudster is at it again. Takes some kahunas to post your ad when you have one currently ongoing. Item 220586768202 Larry Apr-09-10
A:  You gotta be kidding! Guess not. Thanks, Bob Carver
Q:  Hi Bob, any thoughts on how this new tube amp compares with your earlier Silver 7/9 in terms of fidelity, sound quality, current etc..How would compare its current/sound capabilities with the Lightstar Reference? Apr-08-10
A:  Hi '914, Boy that's a hard question - it's sort of like asking how would you compare your first born with his or her siblings. My answer is - I think they are all wonderful and I love them all the same. Though I will say that this amplifier represents my latest thinking year 2010. Good question, hard question. I wish I had a "better" answer, but I don't! Bob Carver
Q:  Bob, will you be putting up another quad of the KT88 Eagles, or possibly, I might be able to buy a set directly from you. Put a question in on the last set but apparently too late. Thanks, Timothy. Apr-06-10
A:  Hi Timothy, I'll put up another set in about a week - I'd do it sooner but I have to go out of town for a week, so I'll do it as soon as I get back. Of course I would like to sell direct to you, but it makes me feel funny, so the answer is no. I apologise from the bottom of my heart, and hope you bid and win next time - I've got my fingers crossed. Thanks for joining my auction, Best, Bob Carver
Q:  hello there! first i have to say that i just love the color you have paint to this quality amps, and wonderful design.. and my question are, is it important to have the same ratet outputs level Vrms from preamp to amplifier?, 2Vrms,1Vrms,or more. and will it be less distortion if i use the same type brand? Kindly regards Tone Apr-06-10
A:  Hi Tone, I like the color too: we tried several different hues and shades of red until we hit on this red. It has a nice sheen and carries just a touch of strawberry with a subtle bit of metallic embedded in that strawberry. As for the preamp, ANY high quality preamp will work great and give great sound - that's because preamps have been essentially standard since the very beginning. Good question, hope this helps, Bob Carver.
Q:  Hi Bob, I bet you didn't waist much time posing and taking that picture of you holding that fantastic amp!! Most every one knows your qualiy amps. It will be interresting to see what the final bid brings! Al G. Apr-06-10
A:  Hi Al, Thanks for your encouraging words - it means a lot to me. We will see when all's well that ends well! Warmest and best, Bob Carver
Q:  Hello- I want to make sure it is really you and not a fake- what is my dogs name? Apr-06-10
A:  Zeus, now for the $64,000 dollar question - is he big or is he small? Thanks for the humor. Bob Carver
Q:  I just wish these were mass produced. Beautiful amps!!!!!!! Well worth the money and then some. Just can't do it working at a group home with juvenile delinquent low functioning sex offenders. Apr-05-10
A:  Hi 'stone1, Even though you can't buy them now, the future definitely lies ahead, and who knows? Maybe someday - even in the very near future! In the meantime your work is absolutely a powerful force for good, and then some. Enjoy window shopping - I do it all the time. Thanks for writing, Bob Carver
Q:  Would you sell a pair of your output transformers and a schematic??? Apr-05-10
A:  Hello 'intell, I'm happy and flattered that you asked for my transformer and schematic. The schematic is free, but it takes me a full day to wind two output transformers; I don't have any extras, so the answer is no regarding them. However, there are some commercial units that will work great - let me think about which ones and where to buy them; let's get in touch after the auction is over and I get back from an out-of-town trip in a week and a half. Hope this helps, thanks for writing, Bob Carver.
Q:  I would be most interested to see what you could create in a state of the art amp, either integrated or power, based on the lowly little 6BQ5 power tube and the 12ax7 signal tube. One that could actually be used with something besides only extremely efficient speakers would be exciting. Has this ever been brought up in any of your discussions. Impossible doesn't seem to be included in the scope of your creations. Come on let's upset the apple cart. Apr-03-10
A:  Hi 'near7, Okay, here goes, I would use the 12AX7 as the voltage amp driving a Stu Hegeman style phase inverter. I would use auto-bias but with a difference - it would have a DC restorer circuit and a voltage clamp for that bias circuit. The 6BQ5's would run cool and the high distortion that ALWAYS accompanies cathode bias systems when driven hard would go away. This would give new meaning to the six barbeque five circuit (6BQ5) - now cool as a cucumber. I calculate about 28 watts rms per pair of tubes. Or 56 watts useing four 6BQ5's. Thanks '7, that was fun! Dream on, Bob Carver
Q:  Hi Bob...Have a pair of your excellent early "Citation brown" mono 180 amps /w original trannys. Sound is gorgeous! So glad to see you've finally rolled a new 'big output iron' of your very own (just like the old Silver Seven days, right!) And looks like even a lack of vintage parts can't slow you down! BRAVO! The vintage tranny's deliver, I think, about 26 A output swing and the wave response capability was very, very high (forget exact V/us) before core saturation set in. How does your new tranny design comnpare w.r.t. the characteristics/specs you observed from the 'vintage-original' trannies you obtained from your college days (installed on the earlier release 'Citation-brown' 180 monos). Thanks, and BTW nice cosemetic improvements on the newer design! - straylight Apr-03-10
A:  Hi 'light, Necessity is the mother of invention; when I ran out of the vintage trannys, I had to figure out how to "roll my own",as it were. I took the vintage ones apart, peered inside and copied them. The winding geometry was vintage, a geometry not used today because it is way too expensive. (And not necessary anyway.) New modern steel and a simple layer wound coil yields great sound. I was not able to find any vintage "iron"(steel actually), so I used the hardest modern steel known to man. I copied the pie winding and put the vintage winding geometry and modern steel together and got the surprise of my life. The output power went up as well as the bandwidth - a few Hertz better. The best part is the two units sound the same, exactly the same! I feel lucky, I got lucky. Thanks for a great question, and I am overjoyed to hear that your "180 brown" amps are still yielding gorgeous sound. Stay in touch, Bob Carver
Q:  Good to see another auction and hope to win this time! I really wish you can manufacture these transformers and offer this as Buy It Now! What is the shipping to London and is this available in 230v? Thanks!! Apr-02-10
A:  Hi ', oops! This is a double - I answered already! Anyway, warmest and best regards, Bob Carver
Q:  Good to see another auction and hope to win this time! I really wish you can manufacture these transformers and offer this as Buy It Now! What is the shipping to London and is this available in 230v? Thanks!! Apr-02-10
A:  Hi again '871, I'm happy to have another go also. Maybe someday I'll manufacture these transformers, but for now this is all I have time for. As for London, the cost will be about U.S. $ 265 each, and yes it's ready to go for either 230 or 240 as the transformer has a split primary winding; it's easy to hook up either way. Hope this helps, Bob Carver
Q:  Bob, AWESOME to see another Pair of GEMS from you again! My bid is in... Palm Springs CF is on Hold at this time, Very sorry but working on it still for down the road. Let me know if your ever this way I could show you my friends Audio store & my set up and buy you a Diet Pepsi. Cheers Apr-01-10
A:  Hi '500, Man you are making my day! Irony has it I was down your way last summer but did not have much time to spend. Maybe this coming summer - I like Diet Coke but a cold Cheers will do as well. Thanks for your bid, warmest and best, Bob Carver

 
 

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Here's the  latest Q&A from Bob's sixth set of tube monoblocks with meters.  This set sold 5/12/10 for $7500, a full 25% less than the previous identical pair.  There's not much new information revealed this time but this pair Bob designated at 240 watts compared to all the others listed as 180 watts.  Again, due to the nature of the way eBay builds it's web pages you should start at the bottom of the post and read upwards to follow chronological order.   This is the first of 2 posts encompassing the full Q&A.  Enjoy!
 
Q:  not a question but a comment on your amplifier. they are certainly built with quality parts but the photographs of you manufacturing your transformers indicate,to me, that you are just having fun doing this. unfortunally i am not in a financial position to bid. i hope you are doing this for a while longer. i certainly would like to bid on a pair of these when my ship comes in. May-03-10
A:  Hey 'mon (70's expression), there is no doubt in my mind that you will someday soon be able to bid high and win. In the meantime, keep on thinking about amplifiers as there scant few dreams that are as much fun or sustaining. I do enjoy winding my own transformers, and painting the chassis in my upstairs paint-booth bathroom. I intend to keep on doing this for a long, long time. Bob's my name, and amps are my game; I could not stop if I wanted to. Bob Carver
Q:  Hi Bob, Let me state for all would-be bidders that this auction is truly from the real Bob Carver. I have the pair from Carverfest so I should know. But now I have to ask how you manage another 60 watts RMS without adding another pair of KT88's. I read below about the 1 ohm spec of 370 watts and how it takes advantage of your DC restorer circuit, but is your new 240 watt spec at 8 ohms? It makes we want to upgrade! Best of luck on this auction to you, Bob. cheers weitrhino May-03-10
A:  Hi 'rama, Yes, the 240 watt specification is an eight ohm spec. And at eight ohms, the amplifier output tubes are loafing, operating at about 62% of maximum capacity (110 + 20) x 3 = 390 watts, and 240 is 62% of 390. An upgrade would give you more power, but not any change at all in the sound. Thanks for writing in with a cool question, one I should have addressed in the auction. Hope this helps, Bob Carver Hope this helps
Q:  As there seems to be some question of Authenticity, will you please verify this auction by answering this question for me. - Aside from a pair of these beautiful amplifiers, what other item did you give away in a raffle 2 years ago at CarverFest in North Carolina? Thank you for your response. Ed May-02-10
A:  Ha! Thought you had me, didn't you? It was a pair of my Sunfire Cinema Ribbon loudspeakers, the ones that got a mind-blowing review by Robert Harley in The Absolute Sound. Wow! I sound like a pitch-man, don't I? Oh well, I can't help it. Bob Carver.
Q:  Hello Bob. Is it possible to have both you and Tubular Joe sign these amplifiers should I win? Hope to hear from you, Kevin May-02-10
A:  Hi 'tvr-1, no problem. However you should know that Tubular Joe has poor penmanship. Just kidding! We will inscribe anything you desire, in gold, on the shiny black output transformers. Bob Carver
Q:  Hello Mr. Carver. I live from Italy. Please tell me it is possible to ship to Italy, and cost. Andrea Croci May-02-10
A:  Hi Andrea, yes I can ship to Italy, and the cost would be about U.S. $350 dollars. Good luck! Thanks for your interest. Bob Carver
Q:  Would you mind telling me your dogs name? There have been quite a few bogus auctions on eBay lately, and I like to make sure you are really Bob Carver. Thanks. Bill May-02-10
A:  Hi 'olt, It's Zeus. He is a small, black British water spaniel with more love than all the amps in the world. Even 240 watt red ones. He has a BIG name though. Thanks for writing, Bob Carver
Q:  Greetings Bob, I am very curious to know how you get so much power from this amplifier at 1-Ohm? Thank you for your time, Thomas in Texas. May-02-10
A:  Hi Thomas, Great question! Easy. Well, maybe not so easy; we have to realize that the mighty KT88 is rated for 110 watts rms audio per pair. Additionally, each tube is rated for 42 watts of plate dissipation(at idle), and most vintage amplifiers operate with the idle dissipation at about three fourths max, or 32 watts per tube. Now thanks to the DC restorer, this amp idles at only 9.75 watts per tube, and about 60% of the remainder becomes available as output power. So we have 110 + 0.6 x 22 watts = 123 watts per pair. Finally, three times 123 = 370 watts total. Thanks for asking a great question, Bob Carver
Q:  Q) Who was the Australian importer when the AL111 was in prodution? Nun_ _ . from Pr_ _ _ . Just looking to verify authenticity. (Hope you knew) Regards, Steven. May-02-10
A:  Hi '87, I can't remember, remember I was old when Atlantis sank, and it was twenty years ago. Besides, you're supposed to ask me something I know the answer to, like my dog's name. I remember that! Thanks for the fun moments, Bob Carver

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Q:  Hi Bob, I have a quick question. I have a Carver M 4.0t Silver Seven Vacuum Transfer Function Amplifier with a Carver C 16 preamp and hi-end Audioquest interconnecion cables. I'm also using your Loudspeaker Control System I usually play classical and jazz music. What kind of speakers do you recomend for my Carver system? What are my options. I have a pair of Bose 502 and it sounds rather dull. Thanks For Your Time Jorge Hernandez Pismo Beach, Ca. May-11-10
A:  Hi '123,Check out my Cinema Ribbon loudspeakers. They were reviewed by Robert Harley in the Absolute Sound and received an incredible review that manufactures normally would die for. Even me. I designed them to have a big soundstage with pin-point imaging within that big enveloping acoustic. Google Absolute Sound and search, or go to the Sunfire web site. I promise as my name is Bob Carver, these speakers are just the ticket for your classical and jazz. Thanks for writing and for the question, Bob Carver.
Q:  -Hello Bob, I have been a fan and happy listener of your incredible insanity from the moment I purchased a new M400 cube amp years ago. Today I have a pair of A760x amps, a C-19 preamp, and a SD/A 490t CD powering a pair of KEF 207/2 reference speakers. My question is this - being unable to muster the mojo to purchase the recently offered pair of Silver-7 tube amps, I am wondering what the audible difference would be if I purchased these tube amps for auction and used them in place of the a760x's.... less power for sure, but honestly I have never owned a tube amp so it is a mystery to me ... any thoughts you could share? Thanks for your time and many years of happy musical experiences. -Gary May-11-10
A:  Hi '6b, Ummm ....your eBay handle sounds like a tube amp. If you have never owned one (a tube amp) before, you are in for a real treat. Once we have experienced a tube amp , we can never go back. As for the power, tube amplifiers sound as if they are about half again as powerful as their power rating would infer. There are a variety of technical reasons for this, but just beyond beyond the scope of my short answer here. Still, it sounds as though you are getting some great sound. Thanks for writing, hope this helps. Bob Carver
Q:  Hi Bob, Unfortunately, I am over loaded with amps at the moment (9 or 10 I think)or I would give these a whirl. I would like to ask you: who you would recommend to service my vintage tube ARC D-79 amp in the Seattle area? I live on Bainbridge Island. I thank you in advance for your reply. Kind regards, Bill Roberts May-10-10
A:  Hi Bill, No sweat, bring it into Rita's Vintage Audio Shop in the old Sunfire factory right here in Snohomish. Bill Flannery is the vacuum tube technician and we work side-by-side on the vintage tube amps and pre-amps on weekends. Bainbribridge is about 35 minutes plus a fun ferry boat ride from Snohomish. Thanks for writing, Bob Carver
Q:  Hi Bob, It is so cool to see you building tube amplifiers! My name is James. I used to work for Carver from 1989 until 1998. I worked for Sunfire from 1998 until 2007. If you ever decide to go into production again building amplifiers or audio equipment, I would love to work for you. I am very good at all kinds of mechanical assembly and soldering work. In fact, in the final days at Sunfire I built the last of the true American built Sunfire amplifiers from start to finish. I am a very hard working and efficient assembler, with great attention to detail and a true commitment to quality. Those tube amps with all that point to point work look like they would be very fun to build! Please give me a call if you are interested in my help. Best Regards, James Keener (425) 346-4856 May-10-10
A:  Hi James, I just answered this. Hi again! Boo! A friendly ghost. Bob Carver
Q:  Hi Bob, It is so cool to see you building tube amplifiers! My name is James. I used to work for Carver from 1989 until 1998. I worked for Sunfire from 1998 until 2007. If you ever decide to go into production again building amplifiers or audio equipment, I would love to work for you. I am very good at all kinds of mechanical assembly and soldering work. In fact, in the final days at Sunfire I built the last of the true American built Sunfire amplifiers from start to finish. I am a very hard working and efficient assembler, with great attention to detail and a true commitment to quality. Those tube amps with all that point to point work look like they would be very fun to build! Please give me a call if you are interested in my help. Best Regards, James Keener (425) 346-4856 May-10-10
A:  Hi James, Sure is fun to hear from you - a nice blast from the past. I have a day job at Sunfire, so I work on these amps in the evening and on weekends, and Tubular Joe builds them when he has time. About eight amps per year. A complete labor of love for us both. Still, perhaps we could build some more if you pitched in - I remember your build quality was extraordinary! Even remarkable and amazing - you were a perfectionist's perfectionist. Let's talk ; call me after the auction is over if you come up for air and if you can. I'm looking forward to talking. All my best, Bob Carver
Q:  HI BOB ¡¡ I HOOCK THEM UP ¡¡ They sound GREAT... ever so sweet " Maravilloso" , Im so Happy , great packing to¡¡ they arrived in perfect shape.. sending pics check your mail THANKS FOR ALL May-09-10
A:  Hi '816, You won my earlier auction! They arrived safe and sound - a long journey, and they work. GREAT, ever so SWEET. I'm happy when you are happy. Happy Birthday, even if the earthquake delayed their arrival. All's well that end well. Thanks for letting us know, Bob Carver
Q:  Bob---I just found a fraudulent amp auction and put a huge bid on it. Thought you'd want to know. May-09-10
A:  Yes I saw it too. And I outbid you. I put a bid of $100,100 dollars. I cannot believe that eBay cannot take this down, but so far they have not done so. They are trying, but said it takes up to 24 hours. It is a one day auction, so that will not help. The real damage is that persons who send them $2000 dollars will certainly lose it all. The good news is you can tell it's fraudulent by my huge outrageous bid! Thanks for letting us know; It help us all. Bob Carver
Q:  Hi Bob, Your favorite fraudster is at it again. lol he doesn't give up. 320529753027 May-09-10
A:  Hey Man, you gotta be kidding! Guess not. Okay, I'll contact eBay, inform them of the fraud, and ask them take it down. Thanks, Bob Carver.
Q:  Hi Bob , Steve here in Washington...I have a question about you sunfire pre amp . the Theater Grand Processor II .....I also have a Sunfire 300~2 amp....On the back of the amp , it has Lab and regular inputs...In the manual , you said to use the Lab if there is no DC output from the Pre....Would it be safe to hook up the Sunfire Pre to the Lab input of the Sunfire amp...And thanks for your time Bob... Steve May-09-10
A:  Hi 'op, Yes it it is safe. The Sunfire has a giant, and I mean a truly huge film output coupling capacitor just to make sure! Hope this helps, Bob Carver
Q:  one last thing i just bought 2 pair of your CRS-3 speakers and want to use one or both pm-900's to design some variable subwoffers to compliment them, so if oyu have any spare ideas or thoughts i could use a few good part names to use in the build. randyhart420 May-09-10
A:  Hi again, Any high quality modern part set will work beautifully. There are many to choose from; you can't go wrong with any of them. Honest. Good luck! Bob Carver
Q:  hi Bob: it is me your problem child again. during the last auction you said you would ( after getting back from being out of town) you would hook my old disabled rear end up with the schematics, parts list and the places to get those impossible to find parts for the amps. i also wanted any recomendations for upgreding the a760X and pm900 as i have two of each. and now i am on disability retirement because of exposure to some bad chemicals at work i would like to tear down the amps and upgrade the resistors and capacitors(your recommendations) of course (not every single little res. or cap but the most affecting ones then try to build on of these because at 10 grand a pair it will be the only way i can own them. i would be graetly appreciativeam going with this one again my email is randyhart429@hotmail.com phone 909-213-4920 i know i am reaching but you are my hero and have been since a m1.0 drove a set of klipsch korners to the brink in 1999. randyhart420 that is ephesians 4:20 May-09-10
A:  Hi '420, I'm glad you wrote in; I have a character flaw - I procrastinate too much. However, I'm working on the updated schematic and a parts list for you. I'll have it done next weekend. Do you have schematics for your Carver amps? Stand by my new friend, Bob Carver
Q:  HI BOB Finally got my hands in your amps¡¡¡ Boy are they beautifull ¡¡ Im shure they will sound " maravilloso" Great. Thanks a lot I going to plug them sunday nigth One simple question are they 220 volts as we requested ?? Best regards from an "honor full " fan May-07-10
A:  Hi '816, They made it! All the way to Chile. One ship, four planes, three trucks, one taxi! Not to mention an earthquake. Yea! Bob Carver PS: They are 220 volts.
Q:  Bob, Sorry to use this format but this is what is available. 37 years ago I met you at a stereo store at Northgate when you told me how to add caps to minimize distortion on an Ortofon cartridge. I asked the owners who you were and when I found out, asked if you had any jobs. You sent me to see the VP (Steve?) at Phase Linear and I was hired to be a tech, specifically QC on the amp line. It was the best company that I have worked for. You know how to treat people/employees and taught me a great deal. I have followed your career and tried to see you a couple of times in other time zones but was out of town or unavailable. So thank you for taking a chance on a fairly disoriented Nam Vet and for giving me a life opportunity. I wish I had the coin for these puppies you are selling. I wish you all the best. Joseph Westphal May-07-10
A:  Hi joseph, I remember that day - it was North west Audio and they carried Ortofon. It was long ago - we were young kids back then and here we are today still in the arena with the music playing on. If you ever make it to my time zone, look me up at Sunfire and let's have breakfast. I wish YOU the best, thanks for taking the time to write and for remembering, it has meant a lot to me. Warmest and best regards, Bob Carver
Q:  Bob, I purchased the set of amps at the end of January and promptly became consumed with business travel and work, trying to keep my business interests alive in this awful economy, so sorry for lack of communications since. However, I wanted to tell you that I've finally had the chance to audition the Chery amps with Infinity RS1's, Gama's, Beta's, Sigma's and Epsilons; Sourced by both vinyl and CD's. As you may recall, my comparison amps include McIntosh 1201's, Onkyo M-508's, Silver 7-t's, TFM-45's & 55's and some other fine amps that I enjoy including some tube units. So the bottom line is simply that the Cheery's, as I like to call them, are truly astonishing. I was wrong to have doubted their ability to drive such power hungry speakers and the result is incredible. We've experimented with the feedback and like 'Classic' best. So thanks much for bringing these to life and keep up the good work! Hope many others can enjoy the beauty of your fine work. May-07-10
A:  Yea! Me too! Bob Carver
Q:  Bob. I don't get along to well with computers and email I can never figure out if a message goes throgh using this ebay route. Did you get a message concerning dc restorer in two stages the secong beginning with OOPS? neal May-06-10
A:  Hi 541', Nope. I did get it the second time you tried. Don't feel funny though - I too can barely turn my computer on - at least that's what my daughter thinks of my computer skills. I deny that of course, and tell her I'm a computer expert. Bob Carver
Q:  Not a question Bob but I want to let you know I how have the second amp finished am am listening to two now instead of one, that I built from the schematics that you sent me, It' up and performing and I must say I think I might have gone to Heaven!!! I have been running the first one while I was building the second one and yes two are twice the sound as one. I have been playing a CD of The US Navy Band and The Sea Chanters and I am hearing sounds that was never there before. Bob I thank you for your encouragement. I don't have words to describe what I am hearing when I listen to my amps. Investing in a pair of your amps is a better investment than the Stock Market, stocks go down the value of your amps go up. Thanks again Bob. Your Friend, "jay" May-06-10
A:  Hi 'music, I love it that you don't have the words to describe what you are hearing when you listen to these amps. But you do - you said you went to Heaven!!! Just don't die first. Thanks for taking the time to write 'music (Man) - means a lot to me, Bob Carver
Q:  Hi Neal again. Maybe my question on the restorer didn't go thru. I will try again. If I recall the idle per tube as about 12 ma, right? Now if the amp is ramped up to full out put with still no waveform distortion, and the signal induced current could be magically stripped away leaving just bias current, what would this current be per tube at this level, with the dc restorer operating? cordially neal May-06-10
A:  Hi Neal, I can tell you have been thinking a lot about the DC restorer. Your question is deep and very sophisticated - here is the answer, but first a thought experiment. Imagine a standard class AB tube amp with each tube biased such that each tube is dissipating 43 watts at idle, idling along at 70 mA. Now we drive the amplifier to full output, say 75 watts and measure the DC value of the cathode current with an ammeter. We write it down. Back to idle. Now we turn the bias control all the way down (max negative bias voltage) to say five mA. We again drive the amplifier to maximum output, 75 watts. We once again measure the DC value of the cathode current. What do you think the cathode current will be? We find that it is almost identical to the current that existed when we operated the amplifier at maximum quiescent dissipation! In other words, the large drive level acts as if it strips away the high idle current. This is an astonishing result, is hard to believe, is non intuitive, AND it is the TRUE nature of a class AB output stage. The DC restorer mimics that nature, except of course on the low end of the output tube dissipation. It works because the crossover distortion (eliminated by idle current) occurs at the zero axis crossing, NOT at the peak of the output waveform or anywhere in between. During the crossover period, a well designed output stage is operating in pure class A and with AB symmetry, hence zero distortion. The DC restorer allows the output stage to operate instantaneously in class A during crossover, but not at large outputs where it would only make things get hot at idle. Remember, at small output levels, class A does not require much current at all. So, as you can see, the answer to your question is 12 mA. This is such a difficult concept to understand and get our arms and mind around, I can see why nobody ever did it before. I got lucky, but only after banging my head against several sliding bias schemes, which are easily understood. Bob
Q:  Hi...I have been looking up information on "pie winding". Now that i have wrapped my brain around the principle, tell me, how many primary and secondary sections are in those transformer? Neal May-06-10
A:  Hi Neal, I'm not saying, it's my secret. However, "The Radiotron Designer's Handbook" published by RCA has an extensive chapter on winding geometry. pages 1205 and 1206, as well as the chapter beginning on page 210. Inspect fig 5.13E on page 213; you will see a pie winding chart showing thirteen sections for a very expensive output transformer. The chart also shows inexpensive transformers with fewer sections, all the way down to only two. There is a great DVD available on eBay called "Audio Transformer, Design and Construction". It contains 24 (!) complete books written by all the great transformer designers from the very beginning through the almost present time. I don't remember the item number but you can find it. Hope this helps. You are going to have lots of fun on your transformer adventure - I just know it - I sure did! Hope this helps, Bob Carver
Q:  Hi Bob My question is not about this auction,although I would Love to own these amps,bob I have a collection of your amps,and the last one I purchsed was a lightstar reference,I always thought it was the last amp you designed before leaving carver corp.can you tell me how of your design is in this amplifier? thanks David May-05-10
A:  Hi David, It was indeed the last amp I designed before I left. I had designed and finished the first prototype, and it was my colleague Vic Richardson who completed that work by putting in the finishing touches and preparing it for factory production. A major undertaking. Vic and I have worked side by side forever since Carver was started, and he currently works in the engineering department with me at Sunfire. The Lightstar circuit with its tracking power supply became the tracking down converter and my first Sunfire amplifier. Bob Carver
Q:  Hey Bob I'm a big fan currently use Slver9T with a carver sonic H C-3 , and a great pair of your ALS111 ribbon speakers. Had it all for about 14 years works flawless,Crystal clear sound and affordable,Thank you May-04-10
A:  Hi '3765, I love it! Man, you are making my day, I enjoy hearing that my designs have been a powerful force for good in peoples lives, and that the music plays on after all these years. Fourteen! Thanks for taking the time to write, it means a lot to me. Bob Carver
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Bob sold yet another pair of his now famous tube monoblocks, this time they are said to be his prototypes with his own self-wound transformers in place of the vintage iron.   Again, the newly wound transformers output power is bumped from 180 watts to 240 watts at 8R.  Stunningly, these amps sold for just $5655.55 on June 19, 2010; a price near the bottom end of all the tube amps so far.  This is the Q&A section direct from the eBay pages preserved here. As always due to the way eBay sets up the page you must start at the bottom of the post and read upwards for chronological order.  This Q&A is split into 2 posts.
 
Q:  I have often read that an Ultra linear output tube connectin is best for class AB amps. Yur amps are not Ultra linear, what is your opinion on this and what is the difference? Thanks for your time, Tim Jun-13-10
A:  Hi 't42, Long ago when I first started desinging tube amps I read the same literature promoting this same idea. However, an important series of converging experiments taught me that an Ultra-Linear output stage was not the best approach. I discussed this with the best and smartest tube amplifier designers in the industry. Each person felt that using an output stage with a regulated screen supply voltage yielded the very finest results. My conversation with Stu Hegeman (so long ago I was just a baby inventor), the designer of the Harmon Kardon Citation amplifiers, confirmed my experimental results. He explained that when using an ultra-linear tap for the screen grids during full signal drive, the screen voltage is unavoidably pushed so low that the maximum output current suffers substantially. Stu Hegeman, a genius, was right! I hope this helps if I haven't put you to sleep with my answer. Good luck, Bob Carver
Q:  Hello, Mr.Carver, I am very interested in these amplifiers. I'm primarily a two channel person and own a pair of Infinity Betas, the original units with a separate external amplifier. These speakers are difficult to drive. Will your amplifier be able to drive them so that I can listen to them at loud but realistic sounds? Thank you for your time, Andrew. Jun-13-10
A:  Hi Andrew, The Infinity Betas are truly great sounding speakers, albeit somewhat difficult to drive. Fortunately they have a separate, dedicated amplifier for the woofers. This allows all of the power from the main driving amplifier to be used more effectively because it doesn't have to operate the woofers. That being the case, this tube amplifier can deliver as much power as anyone could rationally use or need into your Betas. Except for truly crazy audiophiles like me. Just kidding. Great question, thanks for joining my auction, Bob Carver.
Q:  Hey Bob, cool amps! i intent to win and have these set up in my house by my wife's birthday! She's a long time fan of yours. My question is can you autograph it saying "to my loving wife, Happy Birthday always"? Thanks, Gary Jun-12-10
A:  Hi Gary, I'm glad you want to give your wife a nice birthday present. I'm honored, but I have to ask is this similar to a young boy buying his mother a football for Mother's Day? I'm just happy she's a true audiophile. The answer is a resounding YES of course I can autograph anything you wish! Warmest regards Bob Carver
Q:  Hi Bob, those are some beautiful amps, and works of art! If I win the bid, can you put on an IEC type plug so that I could use my own line cord? Thanks,L8tr. Jun-12-10
A:  Hi L8tr, ummmmm, I think that means Later, right? Anyway, the simple answer to your question is NO. Here's why; first of all the hole in the chassis will not accomadate it unless we hand file a larger hole which has to be square and might chip the paint. The scientific reason is that I do not believe in IEC chords. The connections are designed to be universal and they come loose too often. I speak from first hand experience, and besides I get better sound from these amps by using a vintage hard-wired AC line connection. Good question, thanks for asking, Bob Carver
Q:  Hi Bob, Were you a little hesitant to sell your prototype? Just think one of a kind, A classic to say the least, there has never been a pair of amps like these before nor will there ever be another like this pair again? To me it most likely be like giving up and old friend, however, it is great of you to give some blessed person or persons the opportunity to have and hold, (not literally, much too heavy), for fifty year or more. Did you put your all in the building of these guys? best of the best? How long were they in the making? Just curious as to your plans for the original output transformers that you had used in them, you say you are using two of your latest masterpieces in them now, Might the the destiny of the originals be in The Bob Carver Museum? That brings me up to my last question, will the museum be in the "Old Sunfire Building"? I have been wondering about that. Thanks for allowing my twenty questions. "jay" Jun-12-10
A:  Hi Jay, Wow! Here goes, in no particular order: I have indeed put my all into these amps; I've been designing them in my head since 1986, about 24 years. Still, and just the same, I am not at all hesitant about selling my protypes as I think they can be a powerful force for good by making music for the world to hear. The output transformers that were originally in them were robbed long ago in order to build these current amps, so their ultimate destiny cannot be my museum. Not to worry, I did save one transformer for the museum. I am not sure where the museum is going to be. The old Sunfire building is way too big for my modest vintage audio museum. Whew! I hope I answered all 20 questions. Thanks for the great questions, Bob Carver.
Q:  Bob- you are the man!! I have never enjoyed reading the "Ask a question" as I have here. Off Subject, I am a big fan, have been since the 70s. My question: will my M 0.5t sufficently push my recently acquired ALS-IIIs. These are beautiful speakers. Good luck with these amps but I am hopelessly trapped in the past. Walt Jun-11-10
A:  Hi'nic, I am glad to find another soul lost in the past. Since I was old when Atlantis sank, I too am hopelessly trapped in the past. As for the M-0.5t, from a sound quality point of view it will work great. As for having enough power to drive the speakers to a satisfying loudness level, you must determine that for yourself; if you are passionate and crazy (like me)after all these years and want to have Beethoven proud, especially when we turn on the opening chords of Ode to Joy, you MAY have to get more power. Your choice. No right or wrong answer here. Good question. Thanks for asking and for joining my auction, Bob Carver
Q:  Hi, Will a bank or money order work for payment if I win? Thanks Bert Jun-11-10
A:  Hi'63, With a name like that you sound like a special agent! A bank or money order will absolutely work for payment. Bob's my name, amps are my game, and I accept any rational form of payment, send all you've got. Just kidding. Thanks for asking, Bob Carver
Q:  No question for you just a link for you. Carver Amazing LoudSpeaker Original Platinum Edition http://chicago.craigslist.org/chc/ele/1785459378.html Jun-11-10
A:  Hi '154, Wow!! That is really cool. I will look at it this afternoon. Regards, Bob Carver
Q:  Hello Mr. Carver, I own a Margules amplifier, and I like how it sounds and its autobias feature. I imagine that your amplifiers are way ahead of mine in terms of power output and quality sound, but I have two questions: does your amplifiers are autobias, or I need perfect matched tubes? does your amps can be work in triode mode or only ultralinear?. For your attention, thank you very much. Jun-11-10
A:  Hello '77, Wow if you had another number you would sound like an Boeing airplane. No, these amps do not require matched tubes, as the DC restorer eliminates the need. These amps operate in pure pentode mode, with each tube having a separate voltage supply for its screen, yielding the very best sound. Warmest and best, Bob Carver
Q:  Hey Bob, your knowledge of audio is amazing and your attitude with which you answer folk’s questions, with such gitty zeal, is funny and rewarding. I can’t afford these amps at this juncture in life, but I do own a “tube-like” amp; I own a Sunfire. Thinking of getting another one, used, but was wondering what your thoughts were on Hor. and Ver. bi-amping? I keep hearing Ver. is the way to go and I gather I’ll try both when I get the other amplifier, but still desired your feedback on the subject. Jun-11-10
A:  Hi'310, I like your thoughts about my amazing audio knowledge and attitude - you're making my day! More please!! I'm taking a bow, but must be careful not to hurt my back. Most speakers were designed by their designers to be operated from a single full range source. My preference is to honor the designers intent, therefore I prefer and believe the best sound is had by wiring the high frequency drivers and low frequency drivers to the same source, using a separate set of wires for each. An alternate way of doing this, provided we have a tube amp and a transitor amp, it may work best if the high frequency drivers are wired to the tube amp and the base drivers are wired to the transitor amp. Your choice based on careful listening. Thanks for writing, Bob Carver
Q:  Hello Mr. Carver. I own Apogee Scintilla loudspeakers. I am interested in your amplifiers and love the sound of vacuum tubes. Every tube amplifier that i have tried with these speakers has been unable to drive them to an adequate volume level without distortion. Can you reassure me that these will work and, if so, how do they do it? Thanks. Jun-09-10
A:  Hi '113, Driving the Apogees is a matter of raw power as their impedance is about one ohm and their sensitivity is only about 72 dB SPL referred to one watt @ eight ohms. Pretty abysmal. But so what? They are among the most fantastic sounding speakers of all time. I remember first hearing them years ago, and knew I was in the presence of greatness! They were clearly designed by a person who loved music and wanted his speakers to sound as good as he knew how. And never mind the impedance or the sensitivity! He was a true artist, and that approach took courage because they were impossible to drive by normal amplifiers, and that fact alone limited his market tremendously. He was truly courageous. This amplifier has six powerful KT88 output tubes, and can easily deliver 27 peak amperes into a one ohm Apogee load. That's a peak power of over 700 watts! Not only that, but I own a pair of Apogees and have spent countless hours with this amp, together with the Apogees optimizing the whole system. I speak from first hand experience - fear not, these amps will drive your Apogees with aplomb. Good question, hope this helps, Bob Carver
Q:  Would you ship to Hong Kong? I will pay by PayPal. What is the shipping cost? Jun-09-10
A:  Hi 'trad, Yes I will happily ship to Hong Kong, and the cost is about $185 dollars each, or $370 for both. PayPal is good. Thanks for joining in, Bob Carver
Q:  Bob: I notice you have said that these amps are the original prototypes after your (apparently) eventful meeting with Tim de Paravicini. However, you have sold other amplifiers here in the recent past. How do they differ from one another? Thanks a lot! Chris Jun-09-10
A:  Hi Chris, I just knew someone would ask this! The only difference is the output power because of my new output transformers. They sound the same except for that. Cosmetic differences are a change from bright bottom screws to shiny black ones, a shorter roll-bar for the tubes, and the chassis is infinitesimally (3/16 inch) longer to better allow the small tubes and volume control to fit. That's it. Great question, and thanks for asking, Bob Carver
Q:  Hi, Bob. Apparently some would-be scammers have grabbed hold of your items during some of the past auctions and have tried to rip off honest bidders using your pictures and description. To separate the REAL Bob Carver from the scammers, what's your dog's name? Thanks! Jun-09-10
A:  Hi 'qn, It is frustrating to see this happen - eBay has tried hard to keep the scammers shut down, and have pulled those schemers off line as soon as they (eBay) knew about it. Please do not send them any money, no matter what they promise, as you will almost certainly lose it all! They are easy to identify, at least on eBay, as they will not answer any QUESTIONS through eBay, even though they let you send MONEY. My dog's name is Zeus. Bid without fear, Bob Carver
Q:  How can the tubes last for 50 years when most manufacturers recommend changing the tubes in their amps in 3 or so years? Dave Jun-09-10
A:  Hi Dave, That is a very good question! The answer is the DC restorer. Here's how. Most amps idle the output tubes at an average of 32 watts or so. Now the DC restorer allows the tubes to idle at about 9.75 watts. Since tube longevity is roughly proportional to power of the plate dissipation raised to the 2.3 power, we have 32 divided by 9.75 raised to the power of 2.3 = 15.4. Finally, 15.4 X 3 years = 46 years. I have also noticed that many console amplifiers have 50 year old tubes right here on eBay, and those tubes check out great. Great question, hope this helps, Bob Carver
Q:  We live in Germany. I love your amplifiers. My father has been a fan of yours for many years. His birthday is next month. How much would it cost to send these amplifiers to Munich? Danke! Detlef Jun-09-10
A:  Hi Detlef, I can't sing happy birthday in German, but I wish your father a happy birthday sung in English. To the tune of Clair de Lune....Happy birthday to you, happy birthday to you, - I could go on and on. All the way to Munich, Germany is about $240 dollars each, plus or minus. Thanks for asking, Bob Carver
Q:  Hello Bob. Beautiful amplifiers. I doubt that I'll have the coin to win, but I do have a question: How do you get so much power from such a small amplifier? Am I missing something? Thanks. Jun-09-10
A:  Hi 'tss, Thank you, I think they are beautiful too. I spent a lot of time getting the color just right. I tried espresso brown, bright red, several other colors, and finally metallic burgundy cherry red. I liked that the best. As for the power, it was pretty easy actually - all we did was use a lot of output tubes, a transformer turns ratio of about 17:1, a robust high voltage power supply, and the vintage Silver Eagle KT88 easily did the rest. And it's NOT so small-each one weighs almost 45 lbs! Good question, thanks for asking, Bob Carver
Q:  Do you ship to Italy? How much cost? Jun-09-10
A:  Hi 'anb, Yes indeed I do ship to Italy. I can do that because airplanes and ships and trucks arrive in Rome every day. No problem, and the cost is approximately $210 dollars per amplifier. Thanks for asking, Bob Carver
Q:  If you were to send me a dummie case, that is no transformers parts inside, just the finished case with tubes, I'd be glad to photograph it for you professionally for free and return it. Check me out at StudioNOVAimages dot com. Great amps by the way. Best Regards, Tony Nova Jun-09-10
A:  Hi Tony, I can't sing, I can't play baseball, I can't dance and I surely cannot handle a camera well. I can design amps though. You are ON! Thank you for your offer - I will send you a case soon after this auction is over. Thank you thank you! Bob Carver bob.sunfire@gmail.com
Q:  Hi how much do they sell for If a guy whated to just buy him self a set and skip the biding part of ebay ? Jun-09-10
A:  Hi '008, Ummm, good question, let's see, there is paint, the chassis, the vintage tubes, covers and tube sockets, plus line cords and lots and lots of time. It takes me a full day just to wind a pair output transformers - it's a good thing I enjoy building amps so much! I cannot say, how about making me an offer we can't refuse. Seriously. As for this auction, it must run its course. Thanks for writing and joining in, Bob Carver

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Q:  Hey Mr. Carver---how do you have such a nice finish on the first amps? They look so nice and new. Thanks Jun-18-10
A:  Hi 'k67, New finish. Fresh paint, new champagne escutcheons on the front and new champagne trim medallions on the transformer covers. There are some minor paint imperfections and some build-up around some of the small screws, but they are not visible to the naked eye at one foot. Or when riding past on a horse at a slow trot. Good question, Bob Carver
Q:  Dear Bob, I was wondering, after all the years of designing SS amps, you have an affinity for tubed amps, to say the least! When did you realize that you wanted to use tubes? I was also wondering if your Sonic Hologram Generator, which I've been using for 30 years, will work with your Amazings, or even your HTS series? I have a dedicated room made especially for holography, and I prefer it over multi-channel systems! Thank you, thank you, thank you for everything! Tony. Jun-18-10
A:  Hi Tony, Wow! You have a room made for holography? That is so special. Really. As for tube amps, I actually grew up with them - they were my first amp designs, with my solid state designs coming along sometime later with my first amp, the Phase linear 700. Tube amps have always been a true love, and I consummated that love with my Silver Seven vacuum tube amplifier during my Carver days. And yes, Sonic Holography will work beautifully with the Amazings or HTS series. It's important that early reflections be minimized in the setup however. All this is outlined in the manual, and is no different from the setup required for the best conventional stereo presentation. Minimizing early room reflections allows our ear-brain system to do its job and build a sense of three-dimensionality in our minds. We can then use the time cues inherent in the recording, and our brain does the rest, building that large, believable three dimensional space in our minds. Very realistic and enjoyable. Bob Carver
Q:  Hi Bob - beautiful amps...but why did you use that cheesy Radio Shack volume knob? Some sort of yin and yang thing? Ha ha. On a different subject, I have your old M400 cube amp, and it's failed on me once again. Who do you recommend for repairs? -MarkS. Jun-18-10
A:  Hi Mark, I used it because I think it's a beautiful knob. It's shiny polished aluminum, is machined as true as they come, has a perfect-fit center hole without run-out, a steel threaded set-screw, and finally, very nice knurls that ring its outer circumference allowing easy rotation. CHEESY?!?! No way! It's the perfect knob! Who do I recommend for repairs? Me. Send it to Bob, c/o Rita's Vintage Audio Repair. Rita and I will fix it right up - we'll even update it using extra big SOA (safe operating area) output transistors; hopefully it will never fail again. Thanks,Bob Carver
Q:  Hello Bob, Ive always enjoyed youre amps as theyve always been a great value.The M 400 cube was very powerful.I wanted to ask if you remember the Spectro Acoustics 200SR amp and what you thought of the design.I always wondered why no other manufacturers put large meters on theyr amps as well.Thanks for youre time Jun-18-10
A:  Hi 'ales, I do indeed remember the Spectro Acoustics amp - It was designed and built by two talented and passionate guys who worked for me at Phase Linear long ago. They struck out on their own and founded Spectro Acoustics after learning their craft right here in Lynnwood WA. As for meters, I seem to remember that Phase Linear, Marantz, McIntosh and S.A.E. were about the only ones using large meters - okay - maybe they weren't THAT large! Thanks for the fun trip down memory lane, Bob Carver
Q:  Bob, First of all, thanks for your wonderful contributions to the world of audio! I have enjoyed music provided via a TFM-30/CT-3 combo for many years. Quick question: Why are there few tubed amplifiers which incorporate a switch-mode power supply? Seems with the correct filtering and whatnot the DC would be DC akin to that of the analog flavor. Anyhow, Best regards, A6EMech. Jun-18-10
A:  Hi 'mech, I don't know. There certainly is no scientific or sound quality reason that I can think of. Perhaps it's just that mixing vintage tube circuits with contemporary digital switching circuits is too unsatisfying from an emotional or pure intellectual perspective. I'm pretty sure that's the reason! Bob Carver
Q:  Very nice amplifiers! In your listing you discuss input and drive circuits and topologies. I have designed and built an amplifier that uses a JFET differential input stage direct coupled to a 6SU7 long tailed pair (surrent source biased) that has a 6SN7GTB follower. It will swing +/- 250 volts with a THD less than 1% and an IMD of less than 0.1%. It sounds great too. Actually anyone that has auditioned it is amazed. If you have any interest in seeing my circuit, please contact me at tomdooling@charter.net. I'm not selling anything, I'd welcome the opinion of the master. Thanks! Jun-18-10
A:  Hi 'mby, I would love to see your circuit - the more circuits I can study in my life, the smarter I'll become, and it sounds as if your circuit is something to be extremely proud of. There is no doubt that a long tailed pair, current source biased, is definitely one of the best there is. Keep on building and designing! Precious few endeavors are as fun and as rewarding. That's for certain. Thanks for sharing, Bob Carver
Q:  Thanks for the advice to Horizontally bi-amp the Infinity IRS Betas when I get my 2nd Sunfire Signature. Before asking you I only came across one or two of readings that specifically addressed Planar speakers and their thoughts were that Hor. bi-amping was a better way of running them vs. Ver. The Sunfire Sig. I’m running now with the Betas is the 5 ch. model and I have the Mids & Tweets on the Current output and the Bass on the Voltage output. They mate perfectly. That Current option is just the best. You are Bleeping Brilliant. I read that Arnold Nudell designed the Betas Mid/Tweeter column exclusively with tube gear, I’m sure you probably already know that, but I believe that is a major reason your Current outputs mesh so well with the Betas. Now to my question – IF I were to bid, it would be on a future pair of your amps because I’m not financially ready at this point, could I buy 2 sets, meaning 4 amps.? I would be willing to pay the identical winning bid price for the 2nd set Jun-18-10
A:  Hi again '310, Great! You are right about Arnie, he did design them with tube amps in mind - I had many discussions with him about loudspeaker interfaces with vacuum tube amps - and I learned an enormous amount from him. Arnie is one of the great speaker designers of our time. As for your last question - yes, and yes. Happy bidding and lots of good luck, Bob Carver.
Q:  I was 18 in 1985 when I went to work for for the local HI FI shop. I had been going there with My uncle since I was 10. I loved all the equipment, the lights, meters, The smell and of course the sound. I remember after working there for a short while I was told we were taking on a new line of high end gear, it was Carver. I remember coming in a few days later to see several customers, salesmen and My boss standing around a display of Dalquist DQ 9s that were just the day before powered by a huge Yamaha amp and pre amp. As I approached I saw this little gray box with two little LEDs. My boss said check this out. as he cued up the music I remember thinking "aint no way this little thing will drive these DQs like that Yamaha" Wrong!!! I could not belive my ears. over the next few days I listened and was amazed. from that point on I was hooked. I ran two M400t original advents from 19-28.as Money allowed from 29to43 I have 2 1.0T/Polk 1.2tl Bi amped. Just wanted to say Thanks. good job. Jun-18-10
A:  Hi' togo, Hearing about your adventures of long ago makes me smile! It's fun for me know that my amp generated such surprise and astonishment - actually I could hardly believe it myself! Thanks, and thanks for writing, Bob Carver
Q:  Dear Mr. Carver, I found the last question and your answer about bi-amping with a combination of tube [high end] and solid state [low end] amplification to be very illuminating. As a solid state devotee for the past two decades--mainly Carver you will be pleased to learn but Bryston too!-- I feel re-assured by your statement that tube amplification does not necessarily deliver a superior audio experience. Am I going too far with this statement? I always warmed to the idea, in a tube-like way, that Carver "TFM" was a real technology, that solid state amps could deliver the warmth of tubes and then some. Don't get me wrong, I would dearly love to collect a pair of Reference Silver Seven Tube amps (as you will likely be aware, a pair recently sold on eBay for a shade under $19k). It is refreshing to hear, however, that solid state amps should not be discounted. I agree that tube amps are super cool -- I mean warm! Best, Marc + Maria + beagles Vancouver, BC Jun-18-10
A:  Hi 'oose, Absolutely! A great tube amp will sound wonderful, and a great solid state amp can sound wonderful as well. But they WILL sound different. A tube amp generally will yield a more enveloping soundstage and a greater front-to-back depth of field with tight imaging within that soundstage - a very romantic presentation. A well designed solid state amplifier will usually deliver a nice tight focus together with a greater up-front presentation. With these tube amps, a range of possibilities are possible, as the feedback switch and the bias adjustments allow the sound to be changed at will from very tube-like to almost solid state. This emerges naturally as a by-product of the DC restorer and the fact that the bias is "in the green" over a wide range of idling currents. Solid state amps are indeed not to be discounted - and thanks for your thoughtful and on the mark comments - they mean a lot to me. Warmest and best, Bob Carver.
Q:  Bob. You sure got that "mad scientist" look on your face while winding that transformer! Thanks for sharing the pictures and your passion for audio excellence with us! John Jun-16-10
A:  Hi John, You think? Now that I look at it again, I see the only things missing are bugs in my teeth from the winding machine. The camera "stopped" the spokes - they are actually a blur. Bob Carver
Q:  Hi Bob, hugh fan! In a bi-amping configuration, would you use these mono blocks the the upper or lower end? What are the pros and cons for this approach? Jun-15-10
A:  Hi '111, I would use these mono blocks for the high end and a solid state amp for the low end, unless you had two sets of these amplifiers. A vacuum tube amp by its intrinsic nature will yeild better bass because its output characteristic allows the signal to follow the impedance curve of the speaker system, delivering more voltage to the system within about an octive of its resonance frequency. This usually delivers a more satisfying low-end response. However, what normally happens in the real world is that vacuum tube amplifiers lack the raw power to effectively accomplish this; typically a solid state amp is more able to deliver the power needed and therefore works better. But NOT if we have four of these very powerful tube amps. Good question, Bob Carver
Q:  Are the 180 watts rms pentode or triode? Jun-14-10
A:  Hi '4t, This is one of those simple questions with a very complex and extended answer.The answer here is pentode, but that's only the beginning of the story. Long, long ago, in the '30s and '40s the only way to build an amplifier without notch distortion was to build it class A. Many talented amplifier designers worked and worked on the this problem until at last a genius by the name of Williamson arrived and taught the world how to build a class AB output stage that was completely devoid of of notch distortion. This was late '40s - a breakthrough and the hi-fidelity industry took off. However, to work right, triodes were required which limited power efficiency - still, the leap in efficiency from class A to class AB was huge, completely overshadowing the fact that troides were not as power efficient as pentodes. Triodes were still needed to make notch distortion go away as the the art of output transformers had not yet been developed to their fullest. This was was because triodes had a characteristic known as "low output impedance" and could easily overcome the problems of leakage inductance in the output transformer. It took the genius Gordon Gow,a founder of McIntosh to teach us how to build a high efficiency class AB output stage WITHOUT notch distortion. Others followed suit at Marantz, Citation, Scott, Fisher and on and on. Today it is not difficult to build a class AB amplifier without notch distortion, thanks to the amazing pioneering work of those early guys. So - we see we went from triode class A to triode Class AB, and finally to pentode Class AB as the years trolled by. Often old ideas die hard, and to this day a false belief sometimes exists that triodes are still preferred in class A. It IS easier to design with triodes, but a superbly designed pentode stage will easily out-perform even a well designed triode stage. Any difference in sound is associated with the circuit itself, not the choice of pentode or triode. Thanks for the question, Bob Carver
Q:  Hi Bob. The Carver Carver KT88 are gorgeous mono-blocks. If only we all could have one : ). Do you plan to sell more items on ebay? Thank you for the imagination, honesty, and fun you put into audio. Best regards, John Jun-13-10
A:  Hi 'head, Well, as I've said before, Bob's my name, and amps are my game. I could not stop building amps even if I wanted to.I hope YOU are having as much fun as I am in this arena after all these years. Thank you John for your kind words - they really do mean a lot to me. And yes, If only everyone did have one there would certainly be no more wars, sickness or sadness. Of that I am certain! Warmest and best, Bob Carver
Q:  I seem to remember reading this story in 2008! What are your comments to this? http://newsgroups.derkeiler.com/Archive/Rec/rec.audio.tubes/2008-07/msg00075.html Jun-13-10
A:  Hi 'infs, I could not open this. What does it say? Bob Carver
Q:  Hello Bob.I am Karlheinz from Germany.Yes same all , i say you are fantastic electronic inventor.I have a part and no find discription: Carver PG/2 Dual Zone Music /Paging System.If you have the time for sends informations, i say mny thanks to you from Germany Black forrest.Karlheinz Jun-13-10
A:  Hi Karlheinz from the black forest, I used to live in Germany and I remember the park at the end of my block with BIG swings and a teeter-totter. My young German friends and I used to pretend we were in the black forest. As for the Carver system, I have the time , and I would be glad to; I'll look for the information next week when I return home, but please e-mail me late next week and remind me so I won't forget. Warmest and best, Bob Carver
Q:  Mr.Carver, Wow,super nice eye candy.Can you please tell me what caps you used?Thanks, Dave Jun-13-10
A:  Hi '62, I like eye candy too! As for capacitors they are far less interesting than fine eye candy, but here goes. I use metalized film for the interstage coupling capacitors, each sized such that low frequency loop gain and phase shift is just right for perfect sub-sonic stability. The power supply caps are HUGE - way over-kill for energy storage. They can hold so much more energy than vintage designers could ever even dream about - thanks to new capacitor science. Great question, Bob Carver.
Q:  For some reason, the proper Ohm symbol is being changed to a "?" when I send my message. Sorry! Marc Jun-13-10
A:  I got it, no worries, Bob Carver.
Q:  Oops -- "Ω"!! Dear Mr. Carver: In addition to being a big (Bob) Carver fan, I am a big vintage KEF fan. Am I being "unwise" using a TFM-75 to drive my (immaculate) 104/2's [4Ω/200W] or 107/2's [4Ω/400W]? Do note that I am very sensible with the volume, tone and input controls (I use a Carver C- 11 or C-19 Pre-amp). Final comment, I have "less powerful" amps that I can use (e.g. Silver Seven t's, M-4.0t's) but really love the mighty "75"! Thanks for your advice and time. Sure hope I am not unwittingly cooking or otherwise abusing my beloved vintage KEF speakers. Best, Marc + Maria + beagles Vancouver, BC Jun-13-10
A:  Hi Marc and family, Oops, it's good to see you again. Bob Carver
Q:  Dear Mr. Carver: In addition to being a big (Bob) Carver fan, I am a big vintage KEF fan. Am I being "unwise" using a TFM-75 to drive my (immaculate) 104/2's [4Ω/200W] or 107/2's [4Ω/400W]? Do note that I am very sensible with the volume, tone and input controls (I use a Carver C- 11 or C-19 Pre-amp). Final comment, I have "less powerful" amps that I can use (e.g. Silver Seven t's, M-4.0t's) but really love the mighty "75"! Thanks for your advice and time. Sure hope I am not unwittingly cooking or otherwise abusing my beloved vintage KEF speakers. Best, Marc + Maria + beagles Vancouver, BC Jun-13-10
A:  Hi Marc, Maria, and puppies, You are absolutely not being unwise with the TFM-75 provided of course that you use reasonable caution which you clearly are doing. The KEF speakers will let you know in no uncertain audible terms if you abuse them. Especially if you break them. Enjoy the music, play it loud, play it soft, Bob Carver
Q:  Hello Bob Carver, I have enjoyed following you auctions this past year. I was wondering if you had ever measured the total watts being consumed by each amp, out of the wall socket, at idle? I was just curious what one of those Kill O Watt meters might read. I only have a 20 amp circuit coming into my listening room, and several things in there that I fire up when I use it. I have read where you list each KT88 tube at 42 watts at idle, and the DC restorer lowers that to 9.5 watts, but I don't know enough to know if that translates into 42 x 6, or 9.5 x 6 for each amp, or some other number. Sorry for the silly question, but old, inquiring minds are wondering? Thanks if you get time to answer, and best of luck with your "beautiful," both operational, and cosmetic, amp auctions. Jun-13-10
A:  Hi 'igy, Not a silly question at all. And your math is correct, it is indeed 9.5 x 6 plus the power for the tube heaters for a grand total of about 120 watts plus or minus. Thanks for wishing me luck; you won't need luck though as your 20 amp circuit can easily deliver over 2000 watts. Hope this helps, Bob Carver

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The latest of Bob's tube amps were auctioned today for a price of $7101.99, a price which seems much closer to the average than the wild price swings seen over the last few sold.  The Q&A session was a bit more interesting as well with information coming about the amount of energy (in joules) each amp is capable of storing.  Amazingly and typical for Bob, power is quite high and appears to rival even the vaunted Sunfire 300x2 and 600x2 amps.  Read below to discover the truth for yourself.
 
As always you'll have to start at the bottom of the post and read each Q&A upward to follow chronological order.  I wish eBay didn't do it like that, but they do and this post is a direct transfer from the auction pages.
 
Question & Answer Answered On
Q:  Would you be kind enough to entertain a visitor from Vancouver, British Columbia, Canada ? I sure would like to see and HEAR these amps. Vinyl is still me primary source of music. Jul-07-10
A:  Hi 'ord, I would be delighted to. You are just over a two hour drive from my place, so bring your favorite vinyl - I have a special record cleaning machine. I'll be out of town until the middle of next week, so please e-mail me around Wednesday and we'll set a time. There are few things better or more fun. Warmest regards, Bob Carver
Q:  …oh, and how many joules in each of these babies? Jul-06-10
A:  Hi '310, For clarity, joules = energy. These amps have so much energy storage that even I feel a bit guilty of over-kill in the energy storage department. Call it conspicuous energy consumption, but at least when our planet's energy supply runs out, we'll know that (as tube amp aficionados) we will have gotten our fair share of it. Just kidding. These amps have energy storage that could only be dreamed about by vintage designers; they possess approximately 531 joules. Believe it or not! They do. Thanks for asking, Bob Carver
Q:  I own a Sunfire amp and the Current Source outputs are 1 ohm (I think). Curious to what the output impedance is for your new tube amps? Jul-06-10
A:  Hi '310, That is a very deep and important question - more than you might imagine. Let me explain. It is the details of the output impedance that convey so much of the musical romance we hear when listening to great amplifiers. The non-zero output impedance and its variation with frequency give rise to a large romantic and beautiful soundstage. It helps deliver deep front-to-back depth of field, together with sweet imaging within that extensive sound-field. It allows the amplifier to "listen" to what the room is doing acoustically; this room-amplifier interaction provides a sense of believable ambiance and acoustic space that is thoroughly realistic and quite enjoyable. All this for a number of technical reasons beyond the scope of my missive here. My latest thinking on source impedance is 1.30 ohms, my very most favorite number, and sure enough, Zout = 1.30 ohms for these amplifiers! One more thing, it may be changed from much lower than that to much higher by changing the idle current, and is read on the front meter. Great question, hope this helps and that I did not put you to sleep with my long answer. Thanks for asking, Bob Carver
Q:  Hi Bob, Great pair of amps you have there. May I ask, (if it isn't an old family secret), what ingredient(s) you use to make the output transformers, that you are winding for these amps, that you are selling now, superior to the originals that you used to use? They certainly are beauties!!! Best of Regards, "jay" Jul-06-10
A:  Hi Jay, No secrets at all. I'm using oxygen free(well, almost oxygen free)copper wire, the hardest steel known to man, non flammable nitrate transformer varnish, and lots of love with tons of attention to winding geometry detail. Good question, Bob Carver
Q:  Bob: Wanted to send you a note to thank you for my monoblocks. I started buying and building amps (Dynakits)in 1966 and quickly became dissatisfied.I went through a lot of amps including several of the more famous and expensive products on the market. There was always a "bigger or better" available. I had finally deceided that the problem was me, not the amps. WELL, I received your beautiful Monoblocks in Feb. and I truly believe that this search is really over. I have never heard more beautiful, purer sound. From the sound stage to the crisp highs I am completely satisfied. I use them primarily for Phono (a Clearaudio Anniversary with tangential arm and xzy D4 cart) and they noticably upgraded the sound over my Macs and my 5803 Denon. I am trying different preamps and I have to tell you that the old Carver C1 that you reccomended that I try sounds better than the new Music Angel pre that Larry Z gave me to match them. Yor follow thru is appreciated and I will treasure them, Richard Jul-06-10
A:  Hi Richard, Yea! Bob Carver
Q:  Wow two of the worlds best tube amp designers, one amp- must be AMAZING! I will bid for my Stax F81's, that need limitless juice to open up. I use a Luxman M6000 right now, but the promise of tubes like this on the Stax, I have to bid! Jul-06-10
A:  Hi 'att, Hey, I have only stood on the shoulders of the truly greats - Sid Smith, Frank McIntosh, Stu Hegeman, and foremost Tim de Paravicini. I'm lucky to be living now, and was able to rub shoulders with Tim and some of the other great amplifier designers. These amps DO have almost limitless juice to get any speaker to show its true self! Bid away, and if you should win and live within driving distance I'll deliver them myself. Bid away, happy bidding! Bob Carver
Q:  I just wish I had the bucks Bob. I have a mint pair of Vortex Screens I stole for peanuts a few years ago but, as an underpayed aircraft painter, I've yet to get them the kind of juice they deserve. Sorry I can't afford 'em but I'm sure someone will. Maybe someday before the ol'ears give out. Glad to know your still making the world sound better. Jul-05-10
A:  Hi'1914, Thanks for your nice words - there is no doubt in my mind that your ears will last a long time to come. When you are painting, I don't think the loud aircraft engine is running, right? So it cannot harm your ears. Lots of listening left! well, here we are, still in the arena after all these years! The Vortex Screens are quite efficient; they should do very well and present a beautiful sound-scape even without my amps. Enjoy the music, even after all these years! Bob Carver
Q:  Silver Sevens, did you know how desired these have become? A friend of mine has a pristine pair of "amazings" and would love to add some sevens.Any chance of a retro? Jul-05-10
A:  Hi taz154, Yeah I know. No chance of a retro by me - at least for now - but a good guy by the name of James may actually do it in the future. He is working on a pair right now with my blessing, and they are probably about a year away. In the meantime, a good alternative would be to use two of these amps per channel(four in all for both channels). That would make almost a seven, and with slightly more power. No doubt the Amazings would love it and sound stunning! Thanks for writing and for joining my auction, Bob Carver
Q:  Your amplifiers are beautiful. I love the dark red color, very classy. I have a pair of Apogees and I have been using a solid state amp and would like to switch to tubes. A friend of mine brought his tube amp over and it sounded great, but it couldn't drive them well. Do you think your amps would be able to drive them? Also, how is it possible that the tubes in your amps could last 50 years? I believe you, but it just seems to good to be true. Thank You, James. Jul-04-10
A:  Hi'tro, My mother taught me that if something seems too good to be true, it probably is. Forget everything thing your mother taught you about moderation - the tubes WILL last 50 years - here's why. First of all a good output tube that is operated well below its maximum dissipation (heat) level will last a long time, substantially longer than three or four years. They have been designed by our forefathers to do that. Take a look at all the vintage stereo amps listed on eBay - the ones from consoles - their output tubes are about 50 years old and usually check out fine. As for the small tubes, my own experience as a T.V. fixing man in my youth taught me that video pentodes and sync splitters seemed to last forever. They were not quite 50 years old of course, but close. It's the D.C. restorer that allows this extreme longevity, as it reduces the dissipation to about one fourth or one fifth normal practice. Longevity is calculated as related to the 2nd power of the dissipation ratio; 4^2 ~ 16. Finally, 16 X 3 = 48 years. I think the color is nice as well, it's a dark burgundy strawberry with a touch of metallic. Looks better in real life than in the pictures, if I may say so myself! As for driving your Apogees: If you have one ohm apogees, no problem - these amps can deliver over three hundred watts into one ohm. If you have four or eight ohm Apogees, driving them becomes super easy and a walk in the park for these mighty KT88's and powerful output transformers. I specifically designed them to be able to deliver lots of current by having a separate high current supply voltage source for the screen grids. Stu Hegeman (my hero) taught me how to do this long ago. Good questions. Bob Carver
Q:  Hey Bob, I see your at it again. Don't ever stop. Although I could never afford your amps I sure love reading the Q&A's on your auctions. Toodles, Mr.M-500t aka the AVRiser Guy. Jul-04-10
A:  Hi '16dc, Someone once said "never say never" - I don't remember who. Still,I'm honored that you enjoy the Q&A's, truly am. I enjoy meeting everybody, so COME ON all you vacuum tube amplifier aficionados - ask questions! Remember, the only dumb question is the one that is never asked. There is no bad question, none at all! Thanks my friend, Bob Carver
Q:  Hey Bob, I have an older Carver CM-1090 with "Hologram". The output attnuation (volume)will at-times cause a partially grounded crackly muted RH output. Could I use the CM-1090 as a preamp to feed these Carver KT88s and is there any reason I would not want to drive my Dahlquist M-905 speakers with this much RMS power? They are fuse protected and the room is 12'W x 23'L. I listen across the width of the room and have enjoyed the Hologram focus point for many years now. Please advise / Thanks, Mack (VIP, being local to King CO, WA, where am I regarding any "Sales Tax"?) 253-850-5871 Jul-02-10
A:  Hi 'ack, The output volume controls are easily fixed. About the only thing that goes wrong with them is that the pots sometimes get oxidized and dirty - short burst spray with de-oxit will almost certainly cure this problem. I used 200 watts per channel for many years without any trouble at all into my Dahlquist DQ-10s. The only thing I did wrong was rarely, occasionally bottom out the woofer on very low and loud bass notes. The fix was to turn down the volume a tad, then all was well. You should have no problems driving the 905s with this amp. They are quite robust. Hope this helps, Bob Carver
Q:  Hello Bob, As a designer of test equipment and data collection systems, as well as being a vintage audio nut (both myself and my equipment are vintage), I must compliment you on a superb design both topside and below the deck. I would love to own a pair of these beauties, but my wife sets limits on my expenditures for toys, so I will continue to live with my pair of MC60s. What I cannot understand is why you are smiling while winding transformers. Best Regards, Dave Jul-02-10
A:  Hi Dave, Well, thanks for saying such nice things about my design, top and below - I really think this IS my very best work. As for smiling, I must have been thinking about how truly wonderful this transformer was going to be when I finished winding, or perhaps it was simply lots of fun. I do enjoy building transformers, just the same, probably only a science nerd would find himself grinning from ear-to-ear while winding one. Again,thanks for writing, Bob Carver
Q:  holy crap! are you really the bob carver?! if so you ROCK!!! anyways im a young audiophile vintage collector, are you on audiokarma.org? if so i want to add you to my friends list over there!!!!!! thanks! stereo rob. Jul-01-10
A:  Hi'hi fi, Holey Moley Rollers! I love your out-of-sight enthusiasm! I'll pinch myself to see if I'm really Bob Carver. Ouuuuccchh!! Yep, it's me, so count me in. Thanks, Bob Carver
Q:  Hi Mr Carver How are you? A few months ago you said that you have to revise the schematic. you told me in an email to remind you. I have some personal problems, I could not reply to you earlier. I would really like to have one copy of the schematic. I give you my word as a retired electronics technician, I will not sell, or distribute . it is for my personal use.Thanks very much..... Tazz Jul-01-10
A:  Hi Tazz, No problem! Stay tuned because I'm going to update it and post it on this auction towards the end. I hope your personal problems have a happy ending, and no worries about not responding earlier. Use it and enjoy. Bob Carver
Q:  Mr. Carver, if I told you that I could mount a modern PC inside either of the existing amps pictured with only flash memory for the operating system and easy-restore module, would you be interested in hearing how this could be done? I work as a Engineer for the Department of Defense and am currently in Baghdad, Iraq. My area of expertise: http://en.wikipedia.org/wiki/TEMPEST I can minimize RF emissions from modern PC's with very inexpensive shielding so as to not interfere with tubesound. I can build a very small (mini-ITX) PC with a restore function which has never been implemented by any manufacturer or government to date. It entails the use of Flash Memory for a pre-installed OS/software package. A complete restore of all software and operating system is possible within the normal boot time with the flip of a switch.(in seconds) http://en.wikipedia.org/wiki/Free_Lossless_Audio_Codec The makes a PC elegant and uncomplicated with a perfect digital output/0 CPU RF emissions. Jul-01-10
A:  Hi Triple seven, Your idea sounds super intriguing, and no doubt would be fun as well as scientifically interesting, however a problem immediately pops up in my head. The rules of this amp is it's a vintage design, using only parts and hardware available up to about 1960. That's not to say that thoroughly modern ideas and concepts cannot be used, still, PCs were not invented until the recent past, as it were. So . . . . until I make a non-vintage tube amp, the answer must be no in the sense of implementing it in these amp, but as a brain exercise, it would indeed be fun to know about. Stay in touch. Thanks for a great thought, Bob Carver
Q:  Hello Mr Carver. I have seen a few of these amps on ebay over the last year and was wondering how do these amps compare to one of your T-modded Carver amps? What is the difference between a T-amp, and a real tube amp? Thaks for your time. Bill H. Jun-30-10
A:  Hi 'O, Comparing the solid state T amps with these tube amps is very much like comparing our children. Each is truly individual and possesses a unique and different personality. The tube amp is more like a beautiful poem, whereas the solid state amp is more like a science and math person solving a quadratic differential equation. Magic in both! Somehow, on one hand, I dont't feel I answered the question, but I did! Thanks for joining my auction, Bob Carver
Q:  Bob - Nice amps! Very similar to some you had before. I like the OPT! I'm still working with the medium power stuff, 50-60 watts/channel. Have you run across the new Tung-Sol (EH) KT120s? Thanks, Tim Smith Jun-30-10
A:  Hi '95, There are few things in life more rewarding than working with and building amplifiers. Even winding the OPT (output transformer) is lots of fun. As for the Tung-Sol KT120s, I purchased six of them and put them through their paces, and I can honestly say that they are great power output tubes - they do everything right. Mike Mathews and his colleagues did a great job designing these tubes; I think he has been trying for at least a decade to come up with a tube like this. He finally did it! Keep on building! Bob Carver
Q:  Is it possible to have these amplifiers wired for 220v? Do you have an idea what shipping to London England might cost? Looking forward to your reply, Fritz Jun-29-10
A:  Hi Fritz, You can have them wired any way you would like for your country or for your power. Shipping to London is U.S. $526 dollars, plus or minus. That is the cost delivered to the base of Big Ben, your address may be a bit more or less, still that's pretty close. Thanks for writing, Bob Carver
Q:  What is the power consumption of these amps, and what kind of heat will they be putting off? Chris Jun-29-10
A:  Hi Chris, Well, let's see. At idle. KT88 filaments consume 10 watts each. Times six = 60 watts. KT88 plate and screen ~ 9.25 watts X 6 = 56 watts. Small tubes about 8 watts total. Fudge factor of perhaps 15 watts - that's 60 + 56 + 15 = 131 watts, thanks to the DC restorer. Not much for a tube amp; it's so little we can actually hold on to an output tube and not get burned - it's extremely uncomfortable though. The heat it gives off is distributed over the entire chassis, so that at any one spot, the heat is small enough so we can hold or touch it anywhere. Great question, Bob Carver
Q:  Greetings again Mr. Carver: I have wondered for quite some time whether you worked with an industrial designer in your Carver Corp. days to create the bespoke industrial Carver "look." One example, I find the Silver Seven t's to be visually stunning (okay, not as stunning as the gorgeous tube Sevens!). I love the fact that they are so uncompromisingly different from any other solid state amplifier (internally as well). My wife thinks they would look at home in a nuclear missile silo (!) but admits too that they produce gorgeous music when effortlessly driving our vintage KEF Reference Series speakers. I wonder if you would care to comment on the design of the Sevens in particular and how that came about. I would guess that the solid state version was intentionally derivative of the reference tube design. Nevertheless, who created the key design concepts in the first place? You?! Again??!! (o; Best, Marc + Maria + beagles Vancouver, BC Jun-29-10
A: 
Hi guys, Regarding aesthetic appearance: All of my Sunfire designs and most, but not all, of my Carver designs were done by me having as a beginning a rough sketch on a piece of paper inside my notebook. The Silver Seven design emerged as form-follows-function. I copied Stu Hegeman's design of the Citation II; transformers in the back, power tubes in front, a champagne escutcheon on the front. A separate power supply was mandated because otherwise it would have been all but impossible to lift. As for the sonics - it was the "Carver Challenge" of long ago that led me to build the best tube amplifier ever built. At least from my humble perspective. Thanks for the kind words. You have definitely made my day! Bob Carver
 
Q:  Hi will amps operate on 220 volts? We also have 50 Hertz. Je vous remercie de votre réponse. Jun-28-10
A:  Hi new friend, I can tell your English is far better than my French. These amps have been designed to operate on 220/240/110/120 Volts AC and 50/60 Hz. It's a standard transformer with "split" windings and is easily wired for 120 or 240, however the change must be performed by experienced and qualified personnel. I can send it to you with any voltage you want. Hope this helps, Bob Carver
Q:  I've heard of these scams, and I wondered if you wouldn't mind telling us something only you would know to verify your identity. We already know your dog's name. Thanks Jun-28-10
A:  Hi 'oe, Hmmm,let me think. I'll answer a science question since you already know my dog Zeus and his name. Were you aware that the average idle current at 715 volts is .080 amps combined for all six tubes? See it's me! You make me smile. Warmest and best, Bob Carver
Q:  Greetings Mr. Carver. I've been looking at your beautiful amps, and would like to know if I could audition them. I live in Portland, Oregon, so I'm pretty close by. Thanks very much. Jun-28-10
A:  Hi'57t, Portland is just a stone's throw away and a beautiful drive up the coast with the ocean on the left and cliffs on the right. I would be more than happy for you to visit; we could listen into the wee hours. Just bring your favorite vinyl. Or CDs. See you soon, Bob Carver

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Once again, this Q&A is preserved here. Price:  $7700 on 7/29/10.
 
As always you'll have to start at the bottom of the post and read each Q&A upward to follow chronological order.
 
Question & Answer Answered On
Q:  Mine just arrived today! Got home from recording Elio Villafranca. Had to hook them up. WOW!!! Never heard my old stand in Castle Harlech's sound like this. Just HUGE so much control and weight with total delicacy in the quite points. The piano has the weight and tone I just left at the studio when Elio played the Fazioli!!! I am thrilled!! More later got to go listen! Jul-28-10
A:  WOW! I'm glad they arrived safe and sound, and I gotta say, you have made my day! Thanks Robin, Bob Carver
Q:  Hello Bob, I have a question for you about my Sunfire Classic tube preamplifier. My moving magnet phono section sounds terrible. It's real tinny sounding and has almost no low end. I had just got the unit used and the original owner only used moving coil cartridges. I replaced all the tubes (JAN Philips 6922 and Sovtek 12ax7LPS). Why does it sound like this? Jul-25-10
A:  Hi 44' That's horibble! I designed that preamp to sound just the opposite of tinny with a warm and expansive soundstage. I don't know why it sounds horrible, but I do possess the technology to fix it and make it sound great. Is it under warranty? Oh never mind, just send it in to Rita's Vintage Audio and I'll fix it. Warmest and best, Bob Carver
Q:  Those are some great looking amps, only a mad scientist could have designed those babies! I'm sure they sound as wonderful as they look! Now if only that mad scientist could design a tube amplifier that could sound almost as good for an unbelievable low price! An amp in kit form that was even more affordable would be stupendous, then some of us dummies that love electronics might learn something too! Excuse me while I go wipe the druel off my chin. john Jul-25-10
A:  Hi John, I like your sense of style. Mad scientist, huh? Well, I looked at the pictures of me winding the transformers and sure enough, in one of them I look absolutely mad. In truth I was just happy that the transformers were working right. As for a good amp at an unbelievable low price, some of my old amp designs are for sale right here on eBay. They're not tubed though - transistor amps - they don't have my or Tim's latest thinking either. Now you have me drooling too - if you were laughing I would probably rolling over on the floor with the giggles. Thanks for the contagious emotions, Bob Carver
Q:  Hello Bob, Had you seen this: http://www.apogeeacoustics.com/repairsapogeeribbons.html Regards, David Jul-24-10
A:  Hi David, Wow! I had not. Thanks a bunch - looks like I can get my Apogees fixed. Although they sound great, they will undoubtedly sound even better after these folks restore them for me. Thanks again - this really helps, Bob Carver
Q:  Forgive me for being the man with a million questions, but I’m like this if I’m new to something. Being new to tubes I was looking at some on-line, mann there are a lot to choose from, and was wondering would the new Tung-Sol KT120 be okay in your amp or would it stress the transformer or maybe the other parts too greatly to be use in your amp? Tung-Sol KT120 is claiming more power being available with this type of tube and that it can fit right into any socket a KT88 can fit. If they are okay to be use would there be any adjustments that the owner needed to do or would it be a simple swapping-out of tubes? I know it might be best to have a piece of tube equipment before you start trying to tube roll :-D Jul-24-10
A:  Hi again '310, As far as I can tell, Mike Mathews, the owner of Tung-Sol, has been trying to make a tube like this (KT-120) for about a decade. He finally succeeded and succeeded in spades! A tip of my hat to him! I purchased six to try out and found that they are indeed spectacular tubes. Four of them can do the job of six regular KT88's. The only thing I cannot tell is how long they will last, but I can tell how well they work, and they work as well as the best premium tube I've ever had. They can be dropped in most amps that use KT88's or 6550's. The power will not increase one whit though, as the power output is determined by the output transformer as well as the power supply voltage and current. In order to increase output power, the amp must be re-designed using a bigger power transformer, as well as for an output transformer with a different turns ratio. Still,tube swapping is fun, so enjoy it. No apologies necessary for being new to all this. Bob Carver
Q:  I have a few questions on your output transformer design: You mention it is based on some old design, was it the Dyna A431? I had never heard of Adamantine steel, what is this core material and where do you get it from? I know in the past you have provided information on your designs, do you have any plans on sharing winding information on your transformer? Thanks. Jul-24-10
A:  Hi '7543, This transformer was based on the teachings of many - David Hafler of Dynaco, Stu Hegeman, and many others. This unit was most heavily inspired by an unknown scientist who clearly designed output transformers for the United States (see description). Adamantine steel is the hardest steel known to man; it is similar to cold-rolled steel except it is heat treated and hardened as it leaves the rollers. My steel supplier made it for me. I'll be happy to share the winding geometry with you: contact me after the auction is over, and I'll send the drawings. When you build one and power it up for the first time, STAND BACK! Keep the creativity rolling! Bob Carver
Q:  Are xlr connections an option on your amps? Are they a fully balanced design? I have a preamp with balanced connections and single ended connections. I prefer to use the balanced connections when possible. Jul-24-10
A:  Hi '4t, No XLR connections on my amplifiers! I get great sound with a single ended vintage RCA input. The amplifier itself is fully balanced from input to output. Balanced connectors are useful for preventing hum and noise pickup during extra long runs, as in pro applications. As for home audio installations I think great sound comes from single ended vintage connections. Thanks for writing. All the Best, Bob Carver
Q:  Dear Mr. Carver (& Zeus too!), Thanks as usual for being so generous with your time. We have some more queries about your (amazing) Carver Corp. days. 1. Thinking of your Carver solid state amplifiers, would you be so kind as to identify a few designs that you consider to be extra special from a personal point of view (possibly explaining why). 2. Are there any significant differences between the Silver Seven t and Nine t Mono Amplifiers? (Fyi, we own and love a pair of 7t's!) 3. Did Carver Corp. manufacture a tube pre-amp to work with the stupendous Silver Seven Vacuum Tube Amplifier? If so, what was its official model designation? Approx. how many were manufactured (if any)? 4. Can you share one of your "Eureka!" moments when you were designing/engineering? (Of course my wife & I love Dolby Digital (etc.), but we still consider Sonic Holography to be an audio triumph.) Best, Marc + Maria + beagles Vancouver, BC Jul-24-10
A:  Hi Marc, Maria, and beagles, I will do my best here. Tube preamp: yes, Carver Corporation did make one, it was called the Silver One and sported about twenty vacuum tubes, primarily 12AX7's. I cannot remember how many were actually made, but it couldn't have been more then 100 units. As for my Eureka moment, most of my inventions have followed from a long felt need, OR something that I thought would be cool to invent. The Sonic Hologram generator was such an instrument and was the largest selling (unit volume) of my time at Carver. Great questions,hope this helps. Bob Carver
Q:  Hello Mr. Carver, I hope you don't mind a question from a female fan of yours if the answer is no then here goes, at this point in time are you designing or do you have anything new and different apart from these amps that you will be building or are these going to be "The Last Frontier" in tube amps as there are most likely no other tube designers left out there that could top this pair. I enjoy and learn a lot by asking questions and the questions others ask you and your answers and comments. A Fan, Melissa Jul-24-10
A:  Hi Melissa, Great question, and it has so much emotional content that I can't answer it right now. Since I have a day job, finding the time to invent new things is often difficult. I'm sort of thinking about an all vacuum tube preamp for us vinyl lovers. Cheers, Bob Carver
Q:  Mr. Carver, Since Joe, THE master builder of tube amps has a new job, as you mentioned earlier in one of your answers/comments, will this affect your selling on e-bay? I hope it doesn't it's like a continuing Saga. "jay" Jul-24-10
A:  Hi' music, Yes it's sad, but he got a new job, and we have to be happy for him. I'm going to try and get him to stay up late at night and build amplifiers. What can be more important, nes' pa? Wish us luck. Warmest and Best, Bob Carver
Q:  I know this question keeps coming up in different forms all the time, but I think because it seems to truly fly in the face of normal belief. I’m a guy who leaves his gear on 24/7, except if I’m going to be away for days on end I power everything down. What formula are you using, or at least what is the hours-per-day/duration you are factoring in for a projected 50 year life span on these tubes. Bob I believe you, but I need some numbers and it’s next to impossible to convince anyone else of your claim. If I left these amps on 24/7 without eeeeever tuning them off, what can I expect the life to be? ...the 6 big ones and even the 4 small ones? And the audio quality of the tubes at that time? Now you look into that Crystal Ball and tell me damn it! Jul-23-10
A:  Hi '310, I know 50 years seems too long, but it's not(barring a catastrophic failure). First the subjective component. When I was fixing television sets and Hi-Fi consoles for a living long ago, I noticed that some tubes seemed to last forever. 12BY7's, 6BQ5's, 6L6's, and on and on. Today we can buy vintage console amps on eBay that are 50 years old, and the tubes, especially the output tubes, check out fine. I have purchased many Telefunken 12AX7's on eBay (I know, I know, the possessive singular is followed by an apostrophe s, but this is for style); many of them are about 50 years old and test like new! Plus, they are about two dB quieter than even the best brand new tubes. Honest! Now by the numbers: I assume listening to music two and a half hours per day, five days per week. That's less than 33,000 hours in 50 years, a walk in the park for a great tube that is idled at only nine watts (not its specification of 42 watts). Look on eBay and you will find many, many vintage amps with 6V6's inside and they are OLD. And they work great! The secret is to operate them substantially below their maximum rating. Thanks to the DC restorer, these tube operate at 9 watts or so; we can touch the tubes without getting burned, though it will feel uncomfortable for sure! It is absolutely not necessary to leave these amps on continuously - I've designed them to warm up in the first few minutes and sound perfect after about seven minutes. If you left them on 24/7, the output tubes would last about four years is all. The small tubes probably six. Good question that needed some explanation. Hope this helps, Bob Carver
Q:  Without having any kind of test equipment here at home with me, where would you set the gains on the Cherries to match-up with a Sunfire Signature CG? I ask because I would have the Cherries on the Mids/Highs and the Sunfire Sig. would move and cover the Bass duties on my IRS Betas? Would love, but not sure off of the top I could afford 4 Cherry amps to run my speakers :-) I’m considering also a new tube amp from Michael Elliot (formally of Counterpoint), but his is a hybrid tube design and since I have never done tubes I’m kinda leaning towards doing a full tube amp to see what the Tube sound is all about – decisions decisions . Jul-22-10
A:  Hi '310 again, That's an easy question to answer because the gains are the same, exactly the same for both amps. 30 dB. That means the volume controls should be at full clockwise rotation (full up)for equal gain matching. If you want minus six dB, then set them at half mast for a 50% reduction. Or do it by ear. My favorite way. As for decisions, decisions, your instinct is on the mark regarding a hybrid; hybrids put the transistors in the output section, and it is the output section that counts most, so we should always put the tubes there - which means a full-blown tube amp as a practical matter. Thanks for writing, Bob Carver
Q:  Hello, What are the dimensions of these beautiful looking amps? Jul-22-10
A:  Hi '310, Oops!I should have that information in the auction somewhere, or at least a picture of a human model by its side for size perspective. Oh well, here are the numbers. 12 3/4 wide by 15 1/4 deep by 7 3/4 high. this includes about an inch in the back for binding posts and for the power switch handle, as well as about half an inch for the depth of the feet. Hope this helps, Bob Carver
Q:  A couple of questions of mine and then I will let you get back to answering other questions. Hello Bob, A quick question do you find that each and every pair of amps that you build and sell are different and have a uniqueness/personality of their own or do they pretty well run true to the course? Thanks, J Jul-21-10
A:  Hi J, That is a very good question. I actually have spent a lot of work and time to make certain that each amp sounds the same, exactly the same, as the one that was built before. There are about six small parts that are hand selected for optimum performance in each individual amp. Since each one is custom hand crafted, it requires more attention to detail to make sure that each amp is finished, performs, and sounds perfect. We(all of us) are fortunate to have Tubular Joe, the extreme perfectionist, building these amps. Bob Carver
Q:  Hello Mr. Carver, I am one of the truly blessed people that you have helped with the building of their amps by generously sharing your schematics and information with us, there are just not very many master minds out there that would do what you do, let me stop here and say THANK YOU for doing that for me and others, as a result I have a system that only some dream about and was also once a dream of mine but is now a reality, a dream come true. Jay Jul-21-10
A:  Enter your response here Hi 'music, You are very welcome, and I'm glad the amp you built sounds as good in real life as it did in your dreams. Whenever that happens to me, I have to pinch myself to see if it's true and if I'm awake. Thanks for writing, Bob Carver
Q:  Will you be making more of these amps? Jul-20-10
A:  Hi '27, Bob's my name, and amps are my game - I don't know if I could ever stop making amps even if I wanted to. Strictly speaking, Tubular Joe actually builds them in his kitchen whenever he has spare time, and he just got a new job (he's a sound man who puts up and takes down large systems for events in big auditoriums), so I don't know exactly just when he'll be able to build one next. But yes we will, hopefully sooner than later. Thanks for writing, warmest and best, Bob Carver
Q:  I am now bi-amping with a mcintosh 275 and 225. How would your sound compare? The macs are over worked with the polk sda srs speakers I have. Jul-20-10
A:  Hi '27, It's unusual to Bi-amp with two tube amps AND it is the very best way to go IF the tube amps have enough power. Here's why: For the bass, a tube amp is able to follow the increasing impedance rise as the frequency goes lower and lower. This characteristic allows the tube amp to deliver an increased voltage (about 50% more) into the woofer than it can at frequencies removed from from the speaker's bass resonance. Since virtually all woofers have a bass resonance, this yields a warmer rolling bass, a more powerful bass with greater articulation, and usually is more pleasant and fun to listen too. However, in the real world, most tube amps don't have the raw power or current ability (tube amps are voltage devices, whereas solid state amps are current devices) to drive a big woofer to to satisfying undistorted output levels. So by default this job is usually performed by a solid state amp, even though it's output voltage cannot follow the increase in low- end impedance at all. In other words, a tube amp is better than a transistor amp for the low end but ONLY if it can deliver the power and current. Most cannot, so the transistor amp wins by default. These tube amps of mine have lots of power and more to the point have been designed( by virtue of a separate screen supply power source and the D.C. restorer) to deliver 27 amperes of peak current, even more than most transistor amps. As for the mid-range and high-end, the virtues of a tube amp are well understood; your tube amp approach is right on the mark. How would it sound if you used my amp? I think it would sound much better. More drive voltage, more drive current, and finally that undefinable magic that sometimes only a very special tube amplifier can have. Thanks for writing, hope this helps, Bob Carver
Q:  hey Bob: When are you going to put your Scintillas up for auction? I like the idea of an amp/speaker package! Jul-19-10
A:  Hi'costa, Oh man, my Scintillas are very old and in dire need of a magic touch by someone. I have applied automobile rear window conductive paint on the ribbons to repair broken connections, the low frequency resonance of the main diaphragm has shifted so low with endless use and time that on piano music they often sound like a comb kazoo. I could go on and on, but you get the picture, nes' pa? So I'm going to keep them forever for myself; they sound so wonderful - I can forgive their buzzings, thumpings, cracklings as well as their outrageously power hungry diaphragms. Audio Nirvana is so hard to live with sometimes, but always worth it! Warmest and best, Bob Carver
 

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Guest sutekh

Thank you so much for collecting this! Before finding this thread, I only had the last few completed auctions still available on eBay for research / review. I read through every single question and answer saved here before placing the winning bid on the most recent set Monday evening (hope I didn't outbid anyone here...). Buying something this expensive sight unseen and more importantly, unheard is always nerve wracking, but at least armed with the info from this thread I felt like it was an informed decision. Thanks again!

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