The bob carver challenge

Sorry, don't remember this controversy.

Maybe, I was busy enjoying the live music scene, and wasn't into high end hi-fi at that time!

Viren.

no, I do not remember this challenge. Like you I was in grade school back then & was into lo-fi those days! We had a Dual TT & Cosmic amplifier & Arphi Orpheus speakers (my Dad still has those speakers in BOM today! ).

However, Bob Carver was pretty amazing if what was written on that page was true. Duplicating the sound of well reknowned amps at a much lower cost definitely showed he knew what he was doing. I can see why hoity-toity Stereophile was ashamed by him.

Hey thanks for sharing this. This is the first time I am hearing this and must say its very encouraging !

my knowledge on him was very limited to sunfire and what he did to subs .

Duplicating the sound of well reknowned amps at a much lower cost

That too on a bet...challenging the whole world
Man this is awesome...I suppose this guy is highly underrated for his calibre and mastery in audio...I get a feeling that he was suppressed by his rivals..
How come someone so amazing is not as well known..

Bob Carver is well known.

manek.

Manek schrieb:

Bob Carver is well known. manek.

I know he is well known....but just got the feeling that...he should have been better known..

The most amazing trick he pulled off was in the loudspeaker design area.The open baffle Amazing series.Actually using a badly speced woofer to do the work was a fantastic thought process.However much I have tried to have such a woofer made, I come up against one challenge,foam surrounds,I can't seem to get past this hurdle.
Deaf.

THE GENIUS OF BOB CARVER

To me, Bob Carver's greatest genius was his magnetic field amplifier. It was about 8 inches cube and put out 201 watts RMS per channel into 8 ohms. His first few pieces marketed put out 196 watts and the FCC pulled him up for false advertising since he had advertised it as a 200 watt amplifier. He modified it and future production pieces put out 201 watts !

This is, sadly, in sharp contrast to the FCC not bothering at all. The US$ 70,000 CHORD flagship amplifier puts out only 50% of its promised output. The Macintosh 501 mono blocs thermaly shut down if driven to their power output for 10 to 20 minutes. Ditto for the Krell 400 integrated amplifier.

Bob Carver actually shot to fame, producing the (then) worlds most powerful amplifier. The Phase Linear put out 350 watts per channel ( Total 700 Watta) using quite a rudimentary circuit, quasi-complimentary output transistors and no output protection.

That Phase Linear amplifier probably sold most speakers than any other amplifier. Almost every owner blew atleast 1 pair of speakers!

I still have this amplifier in my godown. I bought it to use the chasis but I never got down to doing so.

Many of Bob Carver's other inventions are also significant. He is a flamboyant personality and like Dr. Amar Bose appears in Ads to endorse his products.

CARVER'S CHALLENGE - The COLD FUSION OF THE AUDIOPHILE WORLD ???

Thanks to square wave for (re) opening this topic. Frankly, I am RATHER surprised that almost no one on this forum had heard of this. Maybe screamgigi ? Would be nice to have your feed back on this, screamgigi-ji.


Yes I clearly remember this matter. I was then working in the R&D section developing audio products in Mumbai. Hence this topic was VERY CLOSE to my heart.

Remember, this was pre-internet period when exchange of information was not only slow but very difficult. Foreign magazines cost a warm and subscriber copies were often stolen.

I use to go to the Mumbai USIS to read audio magazines.

To me, the Carver challenge actually represents a MUCH BIGGER issue than simply a victory or loss for Carver or the magazine.

To me this challenge meant that an amplifier sound could be characterised and duplicated using electronic measurement instruments alone. This would seem like the Holy Grail for the audio technical school. It would provide the ultimate test - that scientific instruments could TOTALLY evaluate and even duplicate amplifier sound.

Yes, Carver won the challange. Incidentally he duplicated the sound of the Conrad Johnson valve amplifier by including a small series resistor at the speaker terminal and adjusting the lead compensation in the feed back loop ! Both of these, quite simple procedures.

The process Bob Carver used was to feed a resistor with the 2 amplifiers on either end of a load resistor. The same test signal was fed to both amplifiers and the characteristic of the Carver amplifier adjusted it so that a zero signal appeared across the resistor. This zero signal was supposed to be -50dB or more down from the full signal. (I think he achieved -60 dB but I an not sure). I however do recall that when the cancellation was only -30 dB, the sound differences were audible.

Without sitting in judgement... the Carver amps with these sonic signatures never sold in large quantities.

I liken the Carver challenge to the "Cold Fusion" matter a few years later. For those not familiar with Cold fusion, 2 scientists : Fleischmannn & Pons did an electrolysis experiment in March 1989. They passed a current through heavy water using Palladium (I think) electrodes. Measurement show that more heat was generated than could be accounted for by the electric current.

The experiment implied that fusion could be created in a laboratory beaker, by a single individual. No need to spend billions on fusion reactors. The world was worried. Of course research grants of over a billion dollars were at stake. Even a bigger concern was that a terrorist may be create a fusion bomb (a hydrogen bomb!) using a glass of heavy water and a battery!!! ( Theoretically extrapolating the discovery)

Very quickly, lots of technical papers were written claiming that the cold fusion experiment was a hoax. Fleischmannn lost his job and his student Pons could not find a job after his studies.

The fact is that cold fusion experiments continue to this day on a low key basis or probably on a highly secretive basis. Poor Fleischmannn & Pons

Did Bob Carver stumble on the audiophile industry's Cold fusion ?

Do keep in mind that this was the era when reviewers were just beginning to acknowledge the sound of cable and capacitors.

Component quality and probably system sound had not migrated to the level it is today.

The Conrad Johnson and Carver amplifiers can still be bought in the second hand market today, if someone wants to repeat the experiment.....

hmmmmm...

Something that I felt when I wrote...

I get a feeling that he was suppressed by his rivals..

Some info I got on the net. I quote:

“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.”

Any thoughts ?

amp_nut, that was a wonderful post. bob carver might be perhaps the only single true scientist in the audiophile community
sonic signatures and house sound is perhaps a big can of worms in the industry ?

One reason perhaps for the lack of growth in the industry is just this. lack of transparency and fiefedom in small and forcibly seggregated artificial niches

The story continues... something like this

The embrassed Audio editors decided to test their skills again, after 3 months.

This time, they could differentiate the 2 amps.

Bob Carver's response was that the Conrad Johnson Valve amp's characteristics had drifted ... as valaves are prone to.. and the new Null was only -30dB ( remember I said a -30dB null was audible ? ) and that Bob was not given a chance to readjust his null, to match that of the drifting amp.

Bob Carver then went to court, but the matter was settled by arbitration... and closed. I think Stereophile was then sold. ....

Do note the challenge... he was to make his amp sound like another amp.. another SPECIFIC CJ Piece put in a 'black box'. Probably 2 pieces of the same CJ model from a production run would also Not sound EXACTLY the same, and 2 CJs could also be differentiated in a blind test.

Also because the Carver, 3 months later could be diffenentiated compared to a SPECIFIC CJ PIECE does NOT mean that it was WORSE ( or better) ... Just AUDIBLY DIFFERENT. Though I am sure they would have sounded Pretty similar... Not IDENTICAL.

I sound like a Bob Carver Champion... infact, if Carver is / was correct, then its a triumph of Instrument-philes like me... that too more than 20 Years ago. So why are we still grappling with measurements ?

I get a feeling that he was suppressed by his rivals..

Need not feel so bad for him.. guess he started the sunfire company and made/ makes a lot of money selling amps. And yes, he must have fixed the production problems, Sunfire gear is quite well known in the audio community.

- Debu

My post seems to have killed this thread ??