Can anyone tell me more about Bob Carver and his challenge to Stereophile?

Discussion in 'Audio Hardware' started by fjhuerta, Apr 13, 2006.

  1. fjhuerta

    fjhuerta New Member

    Location:
    México City
    I read in the "tweaks" thread about Bob Carver and a challenge he made to anyone who'd take it. From the Wikipedia...

    Did he duplicate the sound of a tube amp with one of his cheaper amps?!?

    If this is true, are tube amps merely a "tone control"?

    I had never heard about Carver's challenge, but it seems to be something extremely interesting.
     
  2. Dennis Metz

    Dennis Metz Born In A Motor City!

    Location:
    Fonthill, Ontario
    I don't know about the Carver challenge, but I spoke to an individual from Bryston that referred to tube amplifiers as "tone controls"
     
  3. Tubeman

    Tubeman New Member

    Location:
    Texas
    Yes very interesting, needs researching. :agree:
     
  4. Rolf Erickson

    Rolf Erickson New Member

    Location:
    Los Angeles, CA
    "Tone Control", nice term, I like it..

    Yes, a true, perfect amplifier would be the proverbial "Wire with gain". But what I hear discussed often in Audiophile circles, is many adjectives that describe various degrees of "tone" or other words of a kind which convey some variation of sound, or character, instead of "It sounds exactly like the input!"... Which, to my way of thinking, would be a better review of the amp in question... So, "Tone Control" is a very apt phrase to describe amps that don't sound like the input signal..... they ARE functionally, tone controls... My 3 cents (Inflation). R.E.
     
  5. After all, isn't Stereophile all about pleasing it's advertisers? Besides, it seems that such a publication is obligated to put their advertisers and audio equipment manufacturing friends first, and then "sell it to the public". I wouldn't doubt such a story to be true. My thoughts. ......Oh, and one should read Arthur Salvatore's thoughts on Stereophile magazine. Although I may not totally agree with a few of Mr Salvatore's equipment choices/picks/recommendations on his website, I'd say he probably has more credibility than Stereophile ever could. Perhaps I should have listed this in another thread since there's no mention of Bob Carver, but I felt it has to do with challenging the Great and Mighty Stereophile magazine!
     
  6. Mike F

    Mike F Active Member

    Location:
    Toronto
    Now if Bryston made tube amps they might say something else. I like what Tim De Paravicini of EAR has said which is that he can make tube amps sound like solid state and solid state sound like tubes. He makes both.


    That guy comes across as a loon in my humble view.
     
  7. platinum ear

    platinum ear New Member


    IMO It's not unreasonable to state that tube designs impart more sound of their own to the music. This is a very measurable fact and not merely a subjective view. The 'tube' signature is due to a combination of the transfer function, usually low NFB levels, and added distortions from the unavoidable output transformer. If you want a SS design to sound 'tubish' then a starting point would be a single ended driver and output operating in class A with low global NFB. Low NFB ensures a rich harmonic ouput and SE ensures a healthy amount of HDL2 to provide that warm signature. However, IMO you can never really design a SS amplifier that either measures or sounds exactly like a tube design. Yes, you might be able to almost duplicate the performance at a particular operating point and into a specific load impedance but that's about it. Into your usual very complex speaker load impedance and over a wide range of voltages and currents the differences will be very considerable. As I also recall, Bob Carver also tried to emulate the sound of LP with his digital time lens. Some of his research did unearth interesting findings but at the end of the day the digital time lens was worthy of novelty value at best. IMO his tube emulation attempts fall into the same category.
    However, having said all that I do think that B.C. has been and still is a very talented and under rated designer. It's just a pity (from my point of view) that his target was the mass market and commercial dollar.
     
  8. chosenhandle

    chosenhandle Well-Known Member

    Location:
    Minneapolis
    my Atma-sphere tube amps do not have output transformers, which is true of all OTL amps.

    I don't disagree with anything you are saying other than to clarify the point that an output transformer is found on all tube amps.
     
  9. LeeS

    LeeS Tubes Rule

    Location:
    Atlanta
    It depends on the accuracy and neutrality of the tube amplifier. Recent quality tube amps are very neutral based on my experience but some tube do impart a euphonic sound that some find pleasing. My belief is that you can get closer to music via accurate reproduction.

    The history of Bob Carver is pretty interesting but I find his recent amps to sound very thin in the midrange and they don't soundstage very well in my experience. A friend of mine has his latest Sunfire amp and uses it as a backup when the Audio Research tube amps are upgraded and it sounds horrible to my ears. Lots of bass but very muddy in the midrange and highs with not enough detail.
     
  10. Ski Bum

    Ski Bum Well-Known Member

    Location:
    Long Island, NY
    IMO, we are starting to reach an interesting point in power amplifier development. Some state of the art power amps -- both tube and solid state -- are starting to approach the point where the term "perfect" (i.e. the proverbial straight wire with gain) is coming into play. Two truly perfect amps would sound alike, so as amps approach perfection they will start sounding more alike. This is beginning to happen.

    State of the art tube power amps, such as the top VTL and ARC models, have strengths in dynamics, speed and bass control that were previously the sole province of top solid state amps. Similarly, state of the art solid state power amps, such as the top Halcro and DarTZeel models, have strengths in imaging, tone and distortion-free highs that were previously available only in top tube amps. (I could name other manufacturers; these are simply examples with which I am familiar through personal listening.) There was an interesting article in Stereophile a couple of months ago in which a reviewer described his relatively long-term comparision of near top of the line Halcro and VTL models, concluding that they sounded almost exactly the same (notwithstanding totally different design) and that convenience factors (heat, power consumption, interaction with other components, etc) were likely to start being determinative in selecting power amplifiers.

    I understood that Carver was essentially internally EQ'ing his amplifiers to match other amps. His amps of the day were reasonably fast, powerful, low distortion and imaged well, so it was tough to pick out the re-voiced "fake." Today, I think you could EQ a top solid state amp to sound like a selected top tube amp, and vice versa, but you wouldn't bother to make one $20,000 amp sound like another. What made Carver's demonstration impressive was that his "fakes" were far less expensive than the originals. But there is an issue of reliability.

    Carver also produced some solid state amps (the Phase Linear 700 IIRC) that emulated tube amps by burning up under enthusiastic use. I owned a Sunfire (a later Carver company) subwoofer which was the least reliable audio component in my long personal hi fi experience. I also owned a Phase Linear sound reduction device, which was the second least reliable. I am no longer interested in acquiring products from Carver companies. In contrast, I owned two Mark Levinson No. 20 amps and one Mark Levinson No. 23 amp (keep in mind that Mark Levinson is a company that Carver copied in his demonstration) that worked flawlessly for about 17 years. I still own, and would be glad to purchase, Mark Levinson products.
     
  11. LeeS

    LeeS Tubes Rule

    Location:
    Atlanta
    Well said Hal. After ARC, the Halcro amps are my favorites. I don't have any experience with DarTZeel yet which is a good thing for my wallet. :) I also like some of the Edge amps.
     
  12. Metoo

    Metoo Forum Hall Of Fame

    Location:
    Spain (EU)
    After reading your post I started thinking beyond the technology to the marketing level. One of the main factors that help to sell a product, as is the case with artists, is the fact that you can distinguish it from the rest, yes I am talking differentiation. If technology has (almost) come to the point where reproduction is faithful and everybody is selling hardware of the same quality at the same price range, wouldn't manufacturer's think of making their's sound different (external design differences notwithstanding) in order to differentiate their products? If so, wouldn't this be a kind of monkey wrench on the road to accurate reproduction?
     
  13. Ski Bum

    Ski Bum Well-Known Member

    Location:
    Long Island, NY
    The solid state DarTZeel amp actually sounds "tubier" in tone than the current ARC tube amps. (The DarTZeel is also outrageously expensive, even compared to the Halcro, ARC, etc. competition, so watch your wallet.) We're in a strange new world.
     
  14. Pioneer

    Pioneer New Member

    Location:
    Gaithersburg, MD
  15. fjhuerta

    fjhuerta New Member

    Location:
    México City
  16. coopmv

    coopmv Newton 1/30/2001 - 8/31/2011

    Location:
    CT, USA
    I think those Carver products from the 80's were quite good for the money. I still have the CT-3 and TX-2, which are in perfect operating conditions, though neither belongs to my primary or secondary systems.
     
  17. soundQman

    soundQman Idealist of the Musical Apocalypse

    Location:
    Arlington, VA, USA
    I remember reading about that whole thing back when it happened too. I wonder if some of the magazine's advertisers might have exerted pressure on them after that point. They must have been extremely upset, I'm guessing. Seems to me that it wasn't so long after that that the magazine started editorializing against blind testing. Not too surprising. At least they were honest about the results of the challenge.
     
  18. Atkinson was writing about blind tests while still editor of HI-Fi News, before the Carer challange.
     
  19. platinum ear

    platinum ear New Member


    I briefly met Bruce Candy a few years ago during a Halcro exhibition and he gave a brief but very intereresting presention. Unlike the other BC (Bob Carver), Candy promotes himself as an audiophile first and scientist second. I have a great deal of respect for BC and rate his amplifiers up there with the worlds best. What I like about his PA design is that it's a very regular 3 stage design with the usual class AB complementary output. In other words the excellence comes as much from the implementation as it does from his patented output stage feedback nest. Actually, his work gave me an idea that I'm working on now which is a class AB SS output stage using a tube to inject nested shunt FB. The basic theory is that it will reduce THD by a factor of about 10 and at the same time impart a subtle 'tube' look to the transfer function. I'm not expecting it to sound like a tube amp but I'm looking fwd to the outcome.
    I agree that amplifiers whether SS or tube or both are near their zenith right now. The main reason for that is that most designers at last seem to have a grasp of how to correlate measured and subjective performance. There's also no doubt about the importance of pioneering engineers such as Doug Self who went a long way towards unraveling most of the distortion mechanisms.
     
  20. Shakey

    Shakey New Member

    Location:
    Chicago, Illinois
    I always thought this was some marketing ploy myself and that if Carver could do this why not shoot for something special.
    And I have come to think that mating the amp with speakers is a priority. So many amps sound great with some speakers and not others, and vice versa.
     
  21. fjhuerta

    fjhuerta New Member

    Location:
    México City
    From what I read, they tested Carver's modified amp later and they said "Oh, NOW we hear the difference! The test is invalid!". IIRC, Carver said "Yeah, you just proved tubes age and bias values drift over time, so my amp doesn't sound exactly the same anymore". :D

    This was rather obvious. Imagine being one of the guys who sold $15K amps, advertised on Stereophile, and then all of a sudden it was made public that someone could replicate the sound of your amp in a $600 product.

    Bob Carver should get his hands on a $350,000 WAVAC, replicate its sound, and sell it for $600. THAT would rule, and shatter all perceptions of what high-end amplification really is.
     
  22. coopmv

    coopmv Newton 1/30/2001 - 8/31/2011

    Location:
    CT, USA
    Bob Carver has been unusually quiet the past few years. Perhaps his creative juice has run dry.
     
  23. dwmann

    dwmann Well-Known Member

    Location:
    Houston TX
    As I remember it, Carver won the challenge, but his transfer-function mods proved to be unstable and required constant tweaking. The production versions that purportedly duplicated the sound of his tweaked amps DIDN'T duplicate the sound of his tweaked amps, and even Carver admitted that it was impossible to duplicate the results of his tweaking in a production run. Moral: You can make a cheap amp sound like a $20,000 amp if you know what you're doing and are willing to screw around with it all the time to keep tweaking the sound, but you can't BUILD a $600 amp that sounds like a $20,000 amp in a production environment that you can sell to the public.

    His production t versions didn't sound anything like the sound of the amps they were intended to replicate, and even Carver admitted it.
     
  24. fjhuerta

    fjhuerta New Member

    Location:
    México City
    Yes, he did.

    Something I learned about the test - Stereophile did admit their defeat, and then did everything they could to discredit Carver, anyway.
     
  25. soundQman

    soundQman Idealist of the Musical Apocalypse

    Location:
    Arlington, VA, USA
    The thing I remember about Carver is that he invented and patented a really nifty power supply design that was extremely efficient compared to the class-A behemoths that were popular in audiophile circles at the time. I don't remember the technical details so well, but it had a characteristic of being able to draw as much power from the mains as needed when the audio signal and load required it, but otherwise didn't need to heat up your room with constant current to keep the circuits biased. It was even more efficient than the common class AB amplification. So he could could produce these 500 w/channel power amps in a relatively small chassis. That patent should have been an absolute giant killer. He was a very talented designer, no doubt about it. Too bad he has sort of faded from the scene. I suppose he just got old and sort of retired. Or maybe all the lawsuit hassles he went through dampened his enthusiasm for business.
     

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