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View Full Version : Amp Modelling: Bob Carver & Transfer Function Amps



The Grand Wazoo
15-09-2009, 12:31
I heard some guitar amp modelling the other day & was quite surprised at how it's possible to cheaply create a convincing facsimile of a range of different classic amps from a single device.

This brought back memories of the saga of Bob Carver and his Transfer Function Amps of the mid-80's, so I did some web trawling to read a little more on the subject.

For those who know nothing of this, I'll re-tell the story as I understand it:

Carver challenged two audio magazines to select an amplifier for him to test from any maker and price level & he would then make small modifications to one of his own designs and the staff of the magazine would be subjected to a listening test where they would try to distinguish one amp from the other. Carver's amp was quite cheap & he was willing to put it up against anything.

The first magazine to take him up on his challenge was The Audio Critic and they offered a pair of Mark Levinson ML2's. He was successful in matching the sound and no differences could be discerned.

Next up was Stereophile magazine, who supplied the Conrad Johnson Premier 5, a $12K power amp and added the condition that Carver reproduce it's sound within 48 hours. Stereophile were extremely confident that they could easily reveal the difference between the two amps, especially as the testing was to take place in their own premises & with their own ancilliary equipment.

"After the second day of listening to his final design, we threw in the towel and conceded Bob the bout."
"We had thrown some of the most revealing tests that we know of at both amps, and they came through identically. Even on the subliminal level--the level at which you gradually get the feeling that one amplifier is more "comfortable" than another--we failed to sense a difference between the two amps."
"We wanted Bob to fail. We wanted to hear a difference. Among other things, it would have reassured us that our ears really are among the best in the business."
"According to the rules of the game, Bob had won."
"The implications of all this are disquieting, to say the least. If, after only four days of work, it is possible for someone--design genius or not--to make a $700 amplifier sound exactly like a state-of-the-art amplifier costing many times as much, what does that say for the cost-effectiveness of the latter?"

Carver later marketed the $600-700 M1.5t which was supposed to sound like the amps in the challenge and was compared to $4K – 5K models. Later, he produced the Silver Seven, a hugely expensive (10's of thousands of dollars) valve design. In order to prove how he could still model amps, he modelled the Silver Seven with a £600 model, the M 4t Magnetic Field amp. All were, apparently hugely unreliable and the modelled amps needed constant adjustments to keep them sounding like the amps they were supposed to be cloning.

Then there was an exchange of lawsuits between him & Stereophile, where he claimed they were discrediting him, despite admitting to losing the challenge & they sued for his unauthorised use of their copyright.

I seem to remember loving the looks of the both Silver Seven (especially it's power supply) & the M 4t, from photos – never saw them in the flesh.

http://www.wardsweb.org/audio/carver_images/silver7.jpg

Images here:
http://www.wardsweb.org/audio/carver_info.html

So, what I'd like to know is this:

Has anyone on AoS heard any of these machines, or do they know anyone who has?

Did they sound any good?

Did they really do what he said they would?

Is there any more to the story than I remember / have just read?

Spectral Morn
15-09-2009, 18:13
Hi Chris

I used to work for a retailer who distributed Carver for awhile but sadly only the cheaper solid state kit. They did a wonderful tuner at the time. Only thing I have is a Carver MC step up transformer.

I would love to have heard a Silver 7.

I read somewhere recently and I can't remember where, but Bob is building valve amps again.


Regards D S D L

hifi_dave
15-09-2009, 21:07
Back in the 80's I had in a Carver amp for review in one of the mags. I believe it was called the Cube but it might also have had a number - can't remember now.

Cut a long story short, it was specified at hundreds of watts but sounded thin and hard and not pleasant. As the volume was wound up it just sounded grittier and nastier and just didn't drive the speakers well. I declined to review it as I was wary of legal action because (I seem to recall) Carver were hot on that sort of thing.

We also had in the shop for a short audition a pair of speakers which they were promoting as flat panel speakers in a similar fashion to Magneplanars or ML full range ELS. In fact they had a heap of cheap small drivers on a panel covered with a cloth. Pretty dire

I always put Carver products in the same camp as Bose - lots of hype but not a lot of substance. Others may well disagree.

The Grand Wazoo
15-09-2009, 22:17
Hi Chris

I used to work for a retailer who distributed Carver for awhile but sadly only the cheaper solid state kit. They did a wonderful tuner at the time. Only thing I have is a Carver MC step up transformer.

I would love to have heard a Silver 7.

I read somewhere recently and I can't remember where, but Bob is building valve amps again.


Regards D S D L

Yes, the tuners- - I remember there were two or three models that were pretty good, one in particular was fantastic at making a better go of things than almost anything else with the weakest imaginable signal. I can't remember any of the model numbers though!

The Grand Wazoo
15-09-2009, 22:26
The Cube -Yes, I heard one of those once it was like a little yappy dog, lots of noise but it'd run a mile at the first sign of a fight. The Model number was M400 or something like that.

maxrob200
17-09-2009, 04:39
Yes, the M-400 with Magnetic Field Technology or something. Weighed next to nothing, no transformers I believe. Sounded pretty dismal by comparison to other solid state heavies like Krell and Levinson. Later Carver amps did sound better until you push them hard then they seem to clip badly. Never heard or saw the Silver 7

hifi_dave
17-09-2009, 10:26
I might well be wrong but they always seemed to me to be a company where the marketing was much better than the product.:scratch:

The Grand Wazoo
17-09-2009, 13:50
I might well be wrong but they always seemed to me to be a company where the marketing was much better than the product.

Well, that's something that's often said about Carver but I don't think that even that can be really true.

I don't want to appear to be pedantic, but if their marketing was that good, they'd have sold huge amounts of gear – if not to the true and more discerning enthusiasts, then to the average geezer who just wants a bit of hi-fi gear.
I think their marketing effort may have been better than the product, but I'd say that, given the measure of success in marketing is the number of units sold, they were pretty crap at that too! (Though I don't know about their sales in the US)

The fact that we're having this discussion about an intriguingly different piece of hi-fi, yet not one of us seems to have bought a single bit of their kit would seem to back that supposition up.

…..and as above, I've heard them compared to Bose in that respect but the difference is that because their marketing is very, very good, Bose do shift a lot of units (whatever we may think of them).

Ali Tait
17-09-2009, 14:52
Never heard any,but I remember Ferris Bueller had a Carver graphic equaliser!

Spectral Morn
17-09-2009, 15:14
Well, that's something that's often said about Carver but I don't think that even that can be really true.

I don't want to appear to be pedantic, but if their marketing was that good, they'd have sold huge amounts of gear – if not to the true and more discerning enthusiasts, then to the average geezer who just wants a bit of hi-fi gear.
I think their marketing effort may have been better than the product, but I'd say that, given the measure of success in marketing is the number of units sold, they were pretty crap at that too! (Though I don't know about their sales in the US)

The fact that we're having this discussion about an intriguingly different piece of hi-fi, yet not one of us seems to have bought a single bit of their kit would seem to back that supposition up.

…..and as above, I've heard them compared to Bose in that respect but the difference is that because their marketing is very, very good, Bose do shift a lot of units (whatever we may think of them).


I did a MC step up transformer and pretty good it is too IMHO...so there :ner:;):):lol:


Regards D S D L

The Grand Wazoo
17-09-2009, 17:42
Oh yah, You did mention that. oops

The Grand Wazoo
18-05-2011, 23:37
Well Bob Carver has put a new one-off set of these amps that he's just recently specially built on Ebay.
If you ever fancied a pair, this is your chance!
Nineteen bids & just over a day to go. Bidding is currently running at US $22,453.37

http://cgi.ebay.com/NEW-Carver-SILVER-SEVEN-stereo-tube-monoblock-amplifier-/180665282517?pt=Vintage_Electronics_R2&hash=item2a107d6fd5

Alex_UK
19-05-2011, 05:58
Well Bob Carver has put a new one-off set of these amps that he's just recently specially built on Ebay.
If you ever fancied a pair, this is your chance!
Nineteen bids & just over a day to go. Bidding is currently running at US $22,453.37

http://cgi.ebay.com/NEW-Carver-SILVER-SEVEN-stereo-tube-monoblock-amplifier-/180665282517?pt=Vintage_Electronics_R2&hash=item2a107d6fd5

Amazing looking amps - now $31,800! :eek:

Spectral Morn
19-05-2011, 09:27
Are they worth that kind of money? Has anyone ever heard an original set ? 900watts :eek: All muscle and no delicacy ? All interesting questions. As I said earlier in this thread when it stated originally I never got to hear really high-end Carver :( The main stream kit was quite good, certainly in my memory much better than Bose and I have a lovely Carver MC step up :)

Bob Carver was originally involved in Sunfire http://www.sunfire.com/ That still appears to be the case. Not heard or seen any of it either.


Regards D S D L

Macca
19-05-2011, 12:36
They look like crates full of empty milk bottles:)

Barry
19-05-2011, 20:50
I admire Bob Carvers willingness to 'think outside the box'. Some of his latest circuit topology ideas are beautifully simple and elegant and explore little exploited technology such as magnetic amplification. The price to pay for this elegant circuitry are designs that have very low efficiency and pityfully low power.

I have an interest (and a secret hankering) in assembling a 'less is more' audio system comprising a single-ended class A amp (either valved or solid state) with suitably efficient speakers (which despite my, rapidly diminishing, prejudice against horn loaded speakers, are in the frame).