The Carver Amp Challenge and the 21st Century and it's Failure


Some of you may be old enough to remember this article from Stereophile. Bob Carver claimed he could make an amplifier audibly indistinguishable from some of the best from Conrad Johnson. A high efficiency (not class D), solid state linear amp vs. a linear tube amplifier.


https://www.stereophile.com/content/carver-challenge


Carver's approach was to feed a speaker via both amps at the same time using opposite terminals. The speaker itself was the measure of accuracy. Any difference in output between the two amplifiers would cause audible output.


What's super important here is Carver invented a new way to measure the relative difference of amplifiers with a real load.


That's kind of revolutionary from the standpoint of commonly published measurements of amplifiers before. Steady state, frequency sweeps, THD, IM and S/N all failed (to my ears) to express human experience and preference. I remember a reviewer for Audio, I think Julian Hiirsch, who claimed that these primitive measures were enough to tell you what an amplifier sounds like. The man had no ear at all, in my mind.  More here:


https://www.soundandvision.com/content/reconsidering-julian-hirsch

And here was Carver in 1985 cleverly showing that two amplifiers which measured reasonably well, sounded differently. We should also be in awe of Carver's ability to shape the transfer function on the fly. That's pretty remarkable too but not the scope of this post.


My point is, really, Carver showed us a revolutionary way to examine differences between gear in 1985 and yet ... it did  not become widespread.  << insert endless screaming here >>


As far as I know (and that is very little) no manufacturer of any bit of kit or cable took this technique up. We are still stuck in 1985 for specifications, measurements and lack of understanding of what measures cause what effects and end up cycling through cables and amps based on a great deal of uncertainty.


My points, in summary:

  • Most of what we consider state-of-the-art measurements are stuck in the 1970s.
  • There are a number of ways to improve upon them
  • No one has.
  • We should be a little more humble when asserting if it can't be measured it isn't audible because our measurements are not nearly comprehensive
  • I look forward to manufacturers or hobbyists taking modern equipment to pursue new measurement and new insights into our hobby.


Best,
E


erik_squires
i will add your list ignored the great contribution of Dr. Matti Otala...TIM


Sorry, I meant to type that but instead typed IM.

But ... 1970.
I don't think that manufacturers want a revealing measurement that could be used by consumers to understand real world performance, might hurt sales for some high dollar equipment.

I have had two Carver TFM-42 amps driving a pair of Caver Amazing Silvers for around 30 years working flawlessly. I just upgraded speakers to the Legacy Whisper XDS (delivered Saturday), maybe after some time I will take a look at the Carver 350s.
I own a M400T and still use it in my pool table room. I also owned and sold dual M500T’s.
I consider Bob to be a true maverick with his innovative creations. Alas, Bob is getting up in years and is mostly on the retired genius path. So, future products may be limited. But, he did tell me that he was working on a new tube preamp.

After many years of using various amplifiers, I purchased the Bob Carver Raven 350’s and enjoying them as I write this. There was a problem with the XLR output in my unit that was easily fixed, so anyone buying one intending to use the balanced out should contact Bob Carver Corporation or myself for the correction.

ozzy
+1 @elizabeth , and why are there so many Bob haters? 

I also would like to see more user reports about the 75 watt amp.

@Elizabeth, @Lowrider - I think I can shed some light on Bob Carver "haters", although I think the term "hater" is really too harsh, at least for me.  

I met Bob at a CES show many years ago.   We were both a lot younger then and back then he had a personality that just didn't work with me.   I am not sure what it was. Perhaps, I didn't like his bragging about the sound in his booth as a number of his competitors I visited had surprisingly better sound. 

That was one of my jobs at CES, as a  design engineer I had to check out the competition, check out the sound, and meet the designers, and get a feel for their philosophy.   (Analog circuit design is about 1/3 science, 1/3 philosophy, and 1/3 art form.)   Yet there he was Bob telling me his booth had the best sound at the show, and how the sound did this, and did that; yet my ears told me it didn't do any if the things he was claiming.  I guess he expected me to believe what he was saying rather than what I was hearing. 

The reason I walked over to his booth is one of our dealers came by our booth and mentioned how bad that sound was.  So bad he decided right off not to pick up his line.   In any event, I can see how Bob's personality back then could rub people the wrong way.  I still wouldn't use the term hater though.  Not too surprisingly, I never purchased any of his equipment since meeting him that first time.  

BTW, wasn't he the lead designer at Phase Linear?  I seem to think he was.