Ar9Jim

Welcome Sir, The site search feature is a great resource. Search by key words of interest and years of info is available. Good to see you here. Enjoy!

We have an update and good news. Last spring the Black Magic 25 was conceived. During the pandemic, the special 2 part crimson color paint for the crimson line was not available in a consistent, reliable manner. Color variations were unacceptable. The choice was made, to go with the satin black that is the exact match for the majority of black audio equipment on the market today. This baked finish is durable and very consistent. It also resulted in a cost reduction for the customer. The KT120 vacuum tubes, made by a USA company in Russia, became unavailable last spring and as of 12-20-22 have become unavailable again from the manufacturer. The lead times on orders are now unspecified. Using the powerful and plentiful EL-34 tubes, being made in multiply countries, continues to be a good choice during this war time disruption. The EL-34s using the oversized 75 watt power supply, has great headroom and dynamics. The presentation is effortless and dynamic, on par with amplifiers of higher power ratings when operating below its peak power limit. Using the EL-34s, the Black Magic 25 can more than double its power rating to 55 watts @ 1 kHz with less than 1% THD+N. The good news - The changes made to optimize for the EL-34 vacuum tubes, have had no negative effects when using 6550, KT88 and KT120 tubes. Customers can now enjoy a wider selection of tubes in the Black Magic 25.

If you have a Bob Carver amp either solid state or vacuum tube amplifier plugged into a conditioner, regenerator or filter of any type, try the amp plugged direct to the wall. I know the unit may have outlets marked '15 amps', or 'high current' especially for amplifiers vs the other outlets on the device, and a Black Magic 25 or 275 only have a 3 amp fuse, so the device appears more than adequate but like Bob says, "They can not help and may hurt." If you need more outlets or an extension cord, use a high quality power strip or extension cord, like those intended for power tools. Avoid power strips with surge protectors or circuit breakers. Bob explaining the light weight of his vintage amplifier designs, by explaining that, "I'm using the big transformer on the utility pole" is as true today as ever, even with tube gear and voltage demand. The most direct route to the utility companies transformer is best.

One time when discussing the power conditioner and power cord topic with Bob, he mentioned being trained as a physicist. "My views on these subjects are filtered through my physics education." "Some in the industry are promoting improvements with no basis in science." Its interesting how close ASRs measurements and their testing, align with what Bob has been teaching for decades, before the public had free access to test equipment like today. Back at the time when print magazine advertising propaganda was the norm. Today, these devices have their own category of the market. Can there be differences? Yes. Are those differences technical improvements in performance. Not really. Bobs saying, "aerospace grade audio" means science based. Unfortunately science and "audio grade" have an increasingly large disconnect. ASR does a good service revealing those embarrassments to the hobby. The players can't possibly say this science is not well understood, while using a cell phone. I don't agree with ASR testing dynamic voltage amplifiers with resistor drain test, but on many topics, Bobs teachings and ASRs findings agree very well.

Welcome to TCS Sir. There is a huge amount of info here available by search, and the service manual section is the best. Enjoy!

I copied this from a tube amp site. Sums up the differences in amp types very well. Voltage (tube) vs current (solid state). This explains Bob testing and measuring tube amp performance while driving actual dynamic speaker loads during development. The whole tube or solid-state dilemma is somewhat of a misnomer. Once you accept the reality that a tube amp and a solid-state amp are very different in how they operate, you’ll perhaps better understand that each have their own traits. The biggest difference between them is that a solid-state amp is driven by current throughout the output devices and a tube is driven by voltage. Voltage alone can’t drive a speaker, hence the reason for needing output transformers. You’ll notice most stereo tube amps have 3 large, heavy objects, typically at the rear. They are a power transformer and two output transformers (one for each channel) that convert the voltage from the output tubes to current at the speaker posts. A solid-state amp typically has a single power transformer and no output transformers. However, a solid-state output transistor and a tube basically do the same thing. One doing it in silicone with current and the other doing it in a glass vacuum with voltage. Do they sound different? Yes, we believe so. However, some tube companies make their tube amps sound more solid-state like (for power) and some solid-state products can sound very tube-like. A key difference is that a tube product will require a small amount of upkeep and maintenance. For most who desire the benefit of tubes, it’s a small price to pay. Others just don’t want to maintain an amp once installed. Back to the sound. First, let’s squelch the myth that tube amps don’t have strong or controlled bass. Today, that couldn’t be further from the truth. Let’s also put to bed that solid-state amps aren’t smooth. Like any product from any manufacturer, all products have a voicing and color which is why you buy any given product. There are benefits and drawbacks to each, but one must weigh each depending on what you are looking to achieve in your audio system both in terms of sonics and upkeep as well as taking the rest of the system into consideration. So, in doing so, what are the benefits of each? Generally speaking, tubes offer a greater sense of bloom, more texture and realism to vocals and instruments, a richer midrange. Solid-state usually offers more watts per dollar, faster sound, greater detail. Once again these are generalizations. If you have a system that overall is a bit harsh or fatiguing, chances are you could greatly benefit from a tube amp. On the other hand, if your system is flat, sluggish, or too soft sounding, perhaps a quality solid-state amp is the way to go. Other factors of particular importance are speaker load. Some speakers (although few today) require lots of power and very low impedance driving capabilities. In that scenario, a solid-state amp may do better. But, if your speakers have a moderate impedance curve and are of average efficiency, a tube amp can redefine your definition of what a great audio system can sound like.

Bob Carver has been advising people to plug his amplifiers directly to the wall and using the cord in the box is fine. Bobs large amplifiers make use of all the power available from the outlet at times and the dynamics can sag the home circuits power, as most of us have witnessed by the dimming of the house lights during high current demands. Bobs tube amp designs at any wattage rating, like the Black Magic 25 for instance, while its RMS power is conservatively rated, its dynamic power is much greater. In spite of having a 3 amp fuse, it will sag the voltage on a 15-20 amp circuit. Vacuum tubes are voltage amplifiers (think high pressure), while not pulling enough enough current to blow the 3 amp fuse, the voltage will sag. The low impedance resistive load (aka drain test), critical of tube amps on the ASR site, are similar to testing a pressure washers ability to fill a swimming pool and claiming the pressure washer is deficient because it doesn't produce high enough current. The tube amps ability to swing high voltage, in response to impedance increases over a loudspeakers impedance curve is what makes tube amps special. Many things ASR gets right, and I find agreement with their test and what Bob has said for decades on power products. These topics are in agreement, and Bob told us these things long before ASR existed. Bob Carver is science based. His genius will become even more obvious with time. " Plug the amp directly to the outlet, those devices can not help, but they may hurt." "Use the cord in the box, its fine." "A well designed power supply supplies perfect power to the amplifier." Bob. Personally, I use a conditioner on front end components. Not with Carver amplifiers of any type. 2022 is catching up to what Bob told us long ago.

Note the old school distortion analyzer on Bob's bench in the picture of him holding the M400 in one hand. Here is Bob's analyzer that is at the factory today. It looks about the same, although Carver Corp and Sunfire had many I'm sure. He knows these tools extremely well. The scope and voltmeter with the blue tape are Bob's. He has gear at his lab in Snohomish and gear at the factory in Illinois. Either location he is at, the gear he is super proficient with is on hand.

Some pictures.

The amount of work Bob has done in his career is impressive. Not only do we have Bobs black book of most recent designs in the factory vault, there are volumes of notebooks detailing his experiments over decades of research. Bob has literally worn the numbers off his favorite model, of at least one HP Scientific Calculator and was given an NOS model, found by a customer, to replace the worn out unit. Here is a small sample of the notes Bob has taken.

Hi Dutch, Welcome to The Carver Site. Enjoy!

Hi Chris, Welcome to The Carver Site. Enjoy!

My first Carver was an M400. Very happy days indeed! Enjoy!

Might need an LED on your doorbell. Then the man won't take out your door, because you didn't hear them knocking.

Oh man, hope your neighbors are nice like ours were. They called us when their windows rattled, then we backed it down a little. Didn't have compression drivers. You guys are dangerous.😀

One of Bob's philosophies and one of the reasons he has been successful when he has chosen to build lighter weight, lower cost, high headroom designs, for driving dynamic loudspeaker loads, in tube amps or solid state, is higher voltage. A Mcintosh or Dynaco B+ is about 450 volts. A Bob Carver Black Magic 25 or 275 runs at 685 volts, an increase of more than 50%. One key to a powerful, musical and accurate performance is voltage. In Bobs words about the Black Magics, "they make nice wide voltage swings with lots of headroom."

Hi Simply, I believe you found the best thrift shop deal in history. Wow what a find! M500T and C1 are among the favorites. Both the C1 and the M500T are in need of electrolytic capacitor service. The performance improvement will be very obvious. Leaking caps is more about leaking electrically, than physically leaking electrolyte. They look ok, but they are not. Go that far for sure. The MKII can be done DIY.. Its not a simple mod. It involves changing all of the output devices and a considerable amount of work beyond a restoration. Nelion Audio does the MKII routinely. Consider the cost of the parts list alone, vs the cost of Nelion doing the mod complete. Its been a few years since I did a MKII and the site was updated. There is some info here. Maybe one of the guys who has done one lately can point you to the documentation. Welcome to TCS. Jim

Hi Michael, Thanks for sharing your experiences. You certainly have a lot of fun with audio. I had a similar experience starting the tube addiction with the Dynaco's. Bob Carver and Dynacos David Hafler, were friends and liked talking transformers. You have a great attitude considering the many meat suit challenges you face. I hope you find The Carver Site to be an exceptional site that you enjoy. I believe you will find this site warm and friendly, much like Bob Carver himself. It is humbling that you choose to join us. Enjoy the ride here at TCS, I hope we can be a positive musical experience for you. Jim Clark

Hi Tom, Welcome to TCS. Its a friendly bunch of folks to be around. Much like Bob himself. Not your average website! Enjoy!

Hello Duncan, Welcome to the Carversite, Sir. Its a nice warm place when its cold outside. Enjoy!

1980s DDD recordings from DMP (Digital Music Products) have stood the test of time very well. Producer Tom Jung. This disc is said to be recorded "direct to a 2 track digital recorder." No overdubs. The analog purist may be surprised how good this label sounds, having never been analog at any point in the process. DMP in DDD. Mostly a jazz label. https://en.wikipedia.org/wiki/SPARS_code

Good to see you Sir. Welcome Back.

I've been running a prototype Black Magic 25 for a few months. Bob made further changes to optimize for the EL-34 pentode vacuum tubes. The EL-34 has been around since 1955, first produced by Mullard. They are available new today. In the new Black Magic 25 they sound wonderful and provide plenty of power for most applications. Time with these Tung-Sol EL-34s has me anxious to try rolling some brands. Its said that the EL-34 is the most popular audio tube in history. I can understand why the EL-34 so popular. Very musical.. Now I see them everywhere, like in this video.

I have some updates to this thread as of 10-30-22. Bob has made further refinements to the Black Magic 25. This optimization has made it for use exclusively with EL-34 type vacuum tubes (KT types not allowed). The Black Magic 25 Stereo Tube Amplifier has now been released and is IN-STOCK. Made in USA.. $1995 bobcarvercorp.com. Click 'Buy Carver Direct'.

Welcome to TCS Sir. Enjoy!