The Bob Carver Challenge

personal faves?

I like the Kondo M77 pre-amp.

For power amps, all of these are different but I enjoy (yes, the berning), the Border Patrol 300b push/pull, the Kondo 300b push/pull (model escapes after a glass of wine), viva's 845 monoblocks - integrated version of the amp here - http://www.stereophile.com/artdudleylistening/1105listening/.
I suspect David Bernings new monoblocks will be a step up from the ZH270, but haven't snagged a listen to them yet. I dont think they have a UK importer. I'd surely be adding these to the list, based on the other Berning amps I've heard.

I would be the first to admit that 'best' is very subjective, but I'd love a weekend with all of the above, and the lottery funds to choose whatever I wanted...

a little on the david berning monoblock amps

http://www.davidberning.com/products/qz

 

I don't think it does miss the point, I think you are trying to read too much into what Bob was able to do . He was able to mimic the sound of another amp by vastly altering and tuning almost every stage in his own amp. We aren't talking about tweaking one or two components we are talking about modding each stage of the amp, in effect he was 're-making' the other amp by 'hacking' his own. That's not the same as being able to design another circuit to do that from scratch without having the comparator available. He reverse engineered the sound of the other amp, no more no less.

Without the output of the other amp to null he most likely wouldn't have been able to do it- effectively without the physical nulling to show him he was going in the right direction he was driving blind.

I'm sure you'd like it to simply show that all amps sound the same, as that's your bag, but it in fact shows that they sounded different to start with, retaining this even after quite some tweaking. I'm not denying that he was able to make his amp sound the same, but let's not assume that means he could have made the other amp from scratch.

We all know that manufacturers make their own choices in designing amps, they all have a house sound to a greater or lesser extent. The reason that the huge variety of amp sounds and designs still exists is because despite what the measurement warriors might like to be the case- most people don't like characterless amps.

I want my music to sound the way I want it. It has to highlight the things that i find important to increase my pleasure, if you want 'high fidelity' because you think it represent the 'live event' better, then that's great, but don't kid yourself it sounds anything like the real thing- it's just a pale facsimile of real musicians playing real instruments. Believing that your choice is 'better' is no different to Linnies falling for the tune dem because that aligns with their preferences.

 

The point Carver wanted to prove is that amplifier sound can be modelled easily enough and is determined by things we understand. Also that the sound of very expensive 'reference' amplifiers can be replicated at far reduced cost.

I don't think the Carver amp was completely rebuilt - the time indicated makes that unlikely.

You can make music sound the way you want, but amp swapping is a cumbersome, expensive and wasteful way of doing it. Also very hit and miss.
The bulk of the difference comes down to tonality - so do it properly with tonal correction.

Your amplifiers (assuming still Audiolab) are characterless.
Your amplification would remain characterless if you replaced it with Linn, Arcam, Cyrus or Cambridge to give you four examples. However, swap in Berning, Croft or perhaps some Tripath based amplifiers and you'll hear a clear difference. This isn't because the latter are superior - technically they are inferior - and the inferior technical performance will colour the sound.

That is the message of the Carver article, not what people might prefer.

 

Rob,

What do you think Berning does to the signal?

Joe

 

Biggest issue for me is the very high output impedance except on the highest feedback settings. That will change the frequency response on nearly all loudspeakers connected.
It also has switchable NFB so distortion performance will alter (related to the above) , though I've not seen plots for this.

IIRC on the lowest feedback setting is had 7 ohm output impedance - enough to very audibly change the sound of a typical 8 ohm nominal speaker system with passive crossover.

Not replicate but certainly close the gap.
Here is the item in question - £250 special 'mates rates'

 

Rob,

I thought Berning had low output impedance, being an OTL design of some sort. Is that not the case?

Joe

 

Joe,

OTLs have high output impedance.

The Berning is unusual. I recall reading the rationale for the design being to carry the sound of low feedback triodes on a switch mode RF carrier signal.
It's interesting if so, because it fits with Simon's point that you can feed a characterful amplifier through a technically superb 'characterless' amplifier and preserve the character of the original. Have to try that one day (you know me, I'll try it)

 

Rob,

Can you replicate in the other direction  make a SET sound like snappy solid-state amp?

Joe

 

I see one helluva business potential;-)

Rob, how much would you charge me to turn a Radio Shack receiver into an exact sonic replica of a 552/500? I'll pay half down now with the balance upon shipment.

regards,

dave

 

There is business potential, but a lot of people are already taking advantage of it.

 

Rob, I don't disagree that amp sound can be modelled and that many low cost amps are technically superior to many more expensive designs. I do indeed still use the TAG monos and the Passlabs B1 inc Goldpoint potentiometer, so I consider my system to be reasonably transparent, at least until we get to the room/speaker interface, that's getting better slowly...

I tune my system through the room/speaker interface and also through my choice of cart, VTA and tracking weight. That allows me to get the sound I prefer without resorting to esoteric amp surgery from the designer.... ;-)

 

Sadly not Joe.

The device works by altering the power transfer characteristics, pulling it further from something that is notionally perfect.

I don't know the Radioshack receiver Dave, but there isn't much between a 552/300 (not heard a 500) and any competent SS integrated of similar driving ability - unsighted of course.

There are plenty of skanky old amps around built to very low budget that don't perform well - audibly and measurably, so no mystery and i wouldn't suggest these as contenders.
They are invariably very cheap (or hugely expensive...) or old.

 

I love the theory that expensive items full of quality components can be matched for beer budget money.

Its a wonderful theory, and I hope to discover that this is the case one day, I really do. I'll save a fortune!

 

Expensive audiophile components don't always work better... I'd almost go as far as to say usually don't work better.

 

I remember the 'Bob Carver' challenge (although, as far as I am aware he is the only person who attempted the challenge he set). It was all a bit of marketing really, along the lines of 'I can make a cheapish transistor amp that sounds just like the big expensive valve amps'. I also remember the Silver 7 (or something like that) 'state of the art' valve amp he built and the subsequent transistor amp (at a fraction of the price) he marketed as sounding exactly like it. I also remember that no one actually agreed that the transistor version did sound as good as the valve amp it was claimed to emulate - although all seemed to agree that it mimicked it pretty closely (in the same way that Rob Brydon does a very good Ronnie Corbett).

On a slightly different note, are people seriously suggesting that a Cyrus 3 sounds the same as a Quad 34, 303 (or even my own Naim amplification)?

 

I believe they are saying exactly that Ynmoan. A cyrus or a cambridge amp from richer sounds can be made to sound identical to any other amp, and quality of components does not seem to matter in audio.

Perhaps we will see a beer budget version of the kensai with cheap components that measures and therefore performs identically?

I have my £100 ready.

 

Perhaps it can....but it doesn't.

(mind you, some people think that all amplifiers sound the same already - so there's no need to change anything!)

 

His Michael Caine is certainly better than that other fellows.

 

Spend it. Spend your £100 and find a speaker that measures just like a Kensai.
The measured performance is the key and at the heart of the carver article.

On components it depends what you mean by cheap. If you refer to drivers then performance varies hugely so the justification for choosing one over another is obvious.
If you mean resistors, caps, switches and wire then there is no justification for using boutique of expensive versions, unless the specification is clearly superior. it often isn't.

303 has cap coupling on the output, so not in all cases, but put any other Quad power amp with the 34 and yes, near as dammit the same. If you haven't already, download and read the big amplifier blind test article here. I shouldn't think it will convince you of anything but it does address the 'are people seriously suggesting' bit.

 

aha, there we have it you see.
quality of components DOES make a difference. A BIG difference. In a pre-amp I made a few years ago, the differences between identically rated potentiometers was clearly audible. The same applies to woofers, tweeters. The same also applies to capacitors too.

It does seem unreasonable to claim that quality of components in speakers makes an audible difference, but this does not apply to DACs, amplifiers, and other audio components.

If you still disagree, I will back out of the arguement - there is simply no common ground. I would simply agree to strongly disagree.


**edit** forgive my bringing the Kensai into the arguement - a touch unfair... but I saw some real discrepancy between the selling of a multi thousand pound loudspeaker and a statement that cheap amplifiers are state of the art etc

**edit edit**

http://www.audiosmile.co.uk/KensaiAndAdvantage.pdf
this picture of the kensai crossover seems to use boutique ''mills'' resistors, judging by picture alone. Are they?