Ask Bob.. Taking your questions for a Bob Carver video.

[Ar9Jim 4,061]

Dear Carver fans,  UPDATE: We will make a Q&A video in the next week or so while I'm in Snohomish, WA.. Late May/June 2023. Add your questions/comments to this thread. Thanks.

I'm in meetings with Bob several times per week, and can take a few minutes to ask questions and report back to you in this thread. Bob has opinions on most topics that are viewed through his physics perspective. 

 

Here's a question to start that I asked Bob.

Bob, will a high end power cord improve an amplifiers performance over the cable supplied in the box? Answer - No, it will not. Some market improvements with no scientific basis for such claims. 

 

Feel free to ask Bob questions. Please keep them short and direct.  I'll report the answers to your questions back to this thread a couple times per week after the meeting.

 

Hope this is fun and educational. Enjoy !  Ask Bob!

Edited May 21 by Ar9Jim

[wrf 2,666]

Jim,

 

Cool idea.  Two questions have been bugging me ever since I started playing around with Sunfire amplifiers.

 

1.  Bias Adjustment. Where should you set the bias adjustment on Sunfire amplifiers?

2.  Offset Adjustment.  Where should the Tracking Down Converter offset adjustment be set?

 

Perhaps these questions are too detailed.  Perhaps they vary depending on which amplifier you are talking about.  

 

At the moment, I'm working on a Sunfire Cinema Grand Signature 400 x 7.  I've set the bias on all seven channels at 1mv.  Offset at + and - 7 volts.  Seems to work well, but I worry.  I pretty much pulled these number out of thin air.

 

Any suggestions would help.

[Ar9Jim 4,061]

Another question I have asked Bob and his reply. Bob being a physicist, designs products for the given application of reproducing music through loudspeakers. 

 

Question- Bob how are you able to offer an amplifier like the Crimson 275 that only weighs 19 lbs and uses what seem to be undersize output transformers during resistive load test, yet it sounds fantastic, makes lots of power and owners love them? What gives? 

 

Answer- I've been known for designing high performance, lighter weight amplifiers that more people could afford. The smaller output transformers work very well with this high voltage design. They don't experience saturation when playing music into the dynamic loads of loudspeakers.  This reduces weight and cost, without sacrificing the musical performance.  

Edited November 13, 2022 by Ar9Jim

[Ar9Jim 4,061]

3 minutes ago, wrf said:

Jim,

 

Cool idea.  Two questions have been bugging me ever since I started playing around with Sunfire amplifiers.

 

1.  Bias Adjustment. Where should you set the bias adjustment on Sunfire amplifiers?

2.  Offset Adjustment.  Where should the Tracking Down Converter offset adjustment be set?

 

Perhaps these questions are too detailed.  Perhaps they vary depending on which amplifier you are talking about.  

 

At the moment, I'm working on a Sunfire Cinema Grand Signature 400 x 7.  I've set the bias on all seven channels at 1mv.  Offset at + and - 7 volts.  Seems to work well, but I worry.  I pretty much pulled these number out of thin air.

 

Any suggestions would help.

You got it Wayne. Meeting in the am..

[wrf 2,666]

Another Sunfire question.  One I've asked before and only guessed at the answer.

 

My understanding of the Tracking Down Converter in a multichannel Sunfire amp is that the inputs from all channels are combined.  This composite signal is then used to throttle the rail voltage to all channels.  My question revolves around idle and partially loaded channels in the amp.  Given that the throttled rail voltage represents the needs of all channels combined, doesn't this cause problems when one channel is heavily loaded and others are only partially loaded?  Perhaps this isn't an issue with musical loads, but it this something you need to be careful of when bench testing a multi channel amp?

[cuda 463]

Is there any plans to bring back Bobs Latest Amazing Line Source speaker? Or are they a money looser for the company?

[PMAT 1,738]

Question: would a modern designed, advanced material, long format, wide frequency-response ribbon idea still be a viable contender vs the line source ribbon array? 

[4krow 4,010]

I'm still trying to wrap my brain around the idea of using a feedback loop to interact with the speakers/room. I actually get the concept from the view that the speakers can be microphones for the amp. What does the amp do with this information? Is it related to the whole spectrum of signal or just the bass? Thanks.

 

  I talked with an audio engineer friend of mine about this. His version of understanding is that it would sort of like DSP (but not DSP) with a calibrated mic. Well, I get that, but the drivers in the speakers aren't calibrated to the amp in any way, right? So, there is another avenue to use them still I suppose, and this is my curiosity.

Edited November 15, 2022 by 4krow
more info

[Ar9Jim 4,061]

On 11/13/2022 at 6:56 AM, wrf said:

Jim,

 

Cool idea.  Two questions have been bugging me ever since I started playing around with Sunfire amplifiers.

 

1.  Bias Adjustment. Where should you set the bias adjustment on Sunfire amplifiers?

2.  Offset Adjustment.  Where should the Tracking Down Converter offset adjustment be set?

 

Perhaps these questions are too detailed.  Perhaps they vary depending on which amplifier you are talking about.  

 

At the moment, I'm working on a Sunfire Cinema Grand Signature 400 x 7.  I've set the bias on all seven channels at 1mv.  Offset at + and - 7 volts.  Seems to work well, but I worry.  I pretty much pulled these number out of thin air.

 

Any suggestions would help.

Hi Wayne,

The numbers that come to mind are 80-120ma for bias and 12 volts for downconverter offset. Neither adjustment will do harm and the amp will actually function at the extremes of their adjustment range. 

[Ar9Jim 4,061]

On 11/13/2022 at 7:40 AM, wrf said:

Another Sunfire question.  One I've asked before and only guessed at the answer.

 

My understanding of the Tracking Down Converter in a multichannel Sunfire amp is that the inputs from all channels are combined.  This composite signal is then used to throttle the rail voltage to all channels.  My question revolves around idle and partially loaded channels in the amp.  Given that the throttled rail voltage represents the needs of all channels combined, doesn't this cause problems when one channel is heavily loaded and others are only partially loaded?  Perhaps this isn't an issue with musical loads, but it this something you need to be careful of when bench testing a multi channel amp?

Its actually the highest voltage that drives the downconverter but not the combined sum. 

[Ar9Jim 4,061]

On 11/13/2022 at 9:37 AM, cuda said:

Is there any plans to bring back Bobs Latest Amazing Line Source speaker? Or are they a money looser for the company?

The ALS will likely be back in 2-3 years. Right now the new preamp and amplifiers are at the top of the schedule. Bob 

 

I'll be in Snohomish in the near future and will take inventory of aluminum extrusions and plan from there. Jim

[Ar9Jim 4,061]

On 11/14/2022 at 8:52 AM, PMAT said:

Question: would a modern designed, advanced material, long format, wide frequency-response ribbon idea still be a viable contender vs the line source ribbon array? 

Hi Paul, Yes it would. A properly designed long ribbon can perform excellent. 

Edited November 16, 2022 by Ar9Jim

[Ar9Jim 4,061]

On 11/14/2022 at 7:45 PM, 4krow said:

I'm still trying to wrap my brain around the idea of using a feedback loop to interact with the speakers/room. I actually get the concept from the view that the speakers can be microphones for the amp. What does the amp do with this information? Is it related to the whole spectrum of signal or just the bass? Thanks.

 

  I talked with an audio engineer friend of mine about this. His version of understanding is that it would sort of like DSP (but not DSP) with a calibrated mic. Well, I get that, but the drivers in the speakers aren't calibrated to the amp in any way, right? So, there is another avenue to use them still I suppose, and this is my curiosity.

Hi Ken,

1st question- Its the full spectrum. Every sound wave produces a signal that is used by the amp.. 

 

2nd question- I'll ask Bob to explain more about this. He has an interesting voltage feedback and separate current feedback loops. The back EMF from the speakers feeds back to the driver stage of the amp.. I've heard it work, moving from large rooms to hotel rooms at shows. The soundstage details of scale seem to be less effected by room size and shape. Thats a real trick in an average size hotel room, to get the room size to disappear when you close your eyes, and get the sensation of changing physical locations. It works.

 

[Ar9Jim 4,061]

Hello Guy and Gals,

I'll be in Snohomish for 3 weeks working with Bob.

We will be making a simple cell phone video to answer question and dispel rumors. Ask any questions you wish.

Feel free to ask questions and I will read them off from this thread. Bob can answer you directly by name. I'll go back through this thread and catch any previous question that may have been missed. 

I'll try to post the video about 5-25-23.

If you read post that are questionable, please give the person this link. We would be happy to provide the facts to them on video. 

 

Edited May 20 by Ar9Jim

[radtraveller 81]

How can I tell the history of my Silver Seven 900s, their provenance and year of manufacture?

I cannot find a serial number on the outside.

The tech from the shop I bought these from, who checked them over before shipping and changed them to 120v, did not see one internally either. Purchased from an Italian dealer.

With the supply issues for KT120s: What other power tubes can be used in these? I have a few extra KT120s for just in case, but not enough for a full replacement of either side.

Thank you,

Matt

PS.. Any luck finding any manuals?

Edited May 20 by radtraveller

[Kurt 510]

I'd like to ask Bob to talk about styling of the Carver products. How much is he concerned with form as well as function? How much of the design/look of Carver amps was decided by Bob?  What is his favorite looking Carver amp of all time?  

[Rob 3,545]

I would like to ask Bob if he had the overall power of approval for the manufacturing and designing of all of the products that has had his name on them.

 

Or was his circuitry design and innovative ideas the only area in which he played a part in? 

[Ar9Jim 4,061]

Hello,

We will be making the video in a day or two. Feel free to post more questions. It will be fun!

[straylight 356]

Jim,

 

I have had a curiosity about one of Bob's creations that has been eating me alive for quite some time.

So I'd like to ask Bob a few questions about his original CARVER VACUUM TUBE REFERENCE preamp that features both magnetic and moving coil phono input stages. It's an outstanding preamp that has been a real joy to listen to over the years. I listened to the Citation I preamp and Bob's Ref Tube preamp and his has more shear gusto and unbelievable dynamics that can't be matched by the other. No contest IMO. 

 

1) Members of this forum have, in the past, referred to this as the Silver Six preamp. Was this ever intended as a matching preamp for the Silver Seven amplifiers?

 

2) How rare is it and how many units were actually made at CARVER CORPORATION during Bob's time there? (rumor has it that its quite rare)

 

3) Did this reference tube preamp occupy a spot on Bob's test bench? How did he make use of it?

 

3) Is Bob the sole designer of the circuits in the preamp?

 

4) Did Bob voice it to be similar to the Citation I preamp?

 

5) The phono stages are the quietest I've ever experienced, there is no audible hum or hiss even at full volume. How does Bob do it?

 

Edited May 31 by straylight

[straylight 356]

Have one more question...about the original Rootbeer 180 mono amps.

 

Is it possible to upgrade to a higher output tube with the existing trannies and bias circuit? The bias range on this amp is .07 volt to .14 volt. For tubes the KT-150 and KT-120 tubes come to mind as possible upgrades. Not looking to change the characteristics of the sound, just output capability. These amps have the original military grade transformers with 1 ohm tap I believe.

 

. 

 

 

 

 

 

 

 

 

Edited May 31 by straylight

[radtraveller 81]

16 hours ago, straylight said:

Jim,

 

I have had a curiosity about one of Bob's creations that has been eating me alive for quite some time.

So I'd like to ask Bob a few questions about his original CARVER VACUUM TUBE REFERENCE preamp that features both magnetic and moving coil phono input stages. It's an outstanding preamp that has been a real joy to listen to over the years. I listened to the Citation I preamp and Bob's Ref Tube preamp and his has more shear gusto and unbelievable dynamics that can't be matched by the other. No contest IMO. 

 

1) Members of this forum have, in the past, referred to this as the Silver Six preamp. Was this ever intended as a matching preamp for the Silver Seven amplifiers?

 

2) How rare is it and how many units were actually made at CARVER CORPORATION during Bob's time there? (rumor has it that its quite rare)

 

3) Did this reference tube preamp occupy a spot on Bob's test bench? How did he make use of it?

 

3) Is Bob the sole designer of the circuits in the preamp?

 

4) Did Bob voice it to be similar to the Citation I preamp?

 

5) The phono stages are the quietest I've ever experienced, there is no audible hum or hiss even at full volume. How does Bob do it?

 

Sexy.... 🙂

 

[radtraveller 81]

If you could tell a young Bob Carver one thing: What would it be?

 

[straylight 356]

On 5/31/2023 at 5:17 PM, radtraveller said:

Sexy.... 🙂

 

What if you and I could bring the Silver Six preamp and Silver Seven Mono Amps back together again so they could be hooked up and heard in all their glory?  Wouldn't that be a blast from the past and something for all to hear!  

 

Edited Friday at 03:17 AM by straylight

[BrianD 463]

Stray light, I’ve never seen that preamp before.  What is the model of it?  I can’t make it out in the photos.

 

Looks to be a rare one, you are lucky to have it.

[radtraveller 81]

16 hours ago, straylight said:

 

What if you and I could bring the Silver Six preamp and Silver Seven Mono Amps back together again so they could be hooked up and heard in all their glory?  Wouldn't that be a blast from the past and something for all to hear!  

 

Once I get my whole system done and power squared away.

That would be a sight..

I am just north of Reno, NV.