Douglas Self on Negative feedback and distortion

Hammy: That's why i said ALL the spec's have to be kept in perspective and properly obtained, not just "some of the spec's have to be good" or "some of the spec's were obtained in a manner that isn't representative of real world conditions", etc...

El: Nice explanation.

Andy2: Some of the things that you say aren't available from spec's are "kinda sorta" interpretable via spec's. I agree about soundstage width and depth though. Sean
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Sean: what kind of specs that can tell you how good tight and tuneful the bass of an amp?

Andy: How's this for a list? Slew Rate, Rise & Fall Time, Rated Power Bandwidth, Rated Frequency response, Current Capacity ( steady state and peak ), Output Impedance, Square Wave Tilt @ 20 Hz, Power Output @ clipping into various impedances, THD, IMD, S/N Ratio, Quantity of Global Feedback used, Phase Response, Time Delay, etc...

Like i've said before, if one has access to a wide variety of spec's and those spec's were derived using proper testing procedures, one can have a good idea of what to expect from an amp and / or how consistent it will be with different loads. Some amps are sonic chameleons because they don't achieve a high level of electronic stability and this will be reflected in the various spec's / test results. If one familiarizes themselves with the proper interpretation of these spec's, they can get by with just a portion of the above information and make a relatively well educated "guesstimate" in terms of sonic performance. Sean
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PS... Since some spec's are influenced by others, it's possible that a manufacturer could leave out specific spec's that would explain why others would look so good on paper, yet sound so bad in real life. That's why more info is always a good thing as it gives you more of an explanation as to what is going on in the grander scheme of things.

Sean, we could get you a list of highend amps, give you the specs- I am sure you couldn't answer andy's question. Especially more subjective things like listener fatigue. Look, Eldartford's answer makes perfect sense. Of course Andy and I don't ignore specs. I need to know the impedance of a cartridge or speaker, whether the designer uses negative feedback to cover a crap design (Gives great spec though), what the sensitivity of a speaker is ...

A lot of what you say has merit. It's not as black or white as I have portrayed it... I just know from experience that you hear music, not paper. It may be the bees knees on paper, and sound like crap. A lot of bob carver's products were like that. The specs from the lab were impressive, but in the real world the amps needed more current than a twenty amp residential circuit could provide. Oops! Worked great in the industrial lab though- loved those specs. My previous example of ultrasonic harmonic distortion is a good one as well- you can't test for something if you don't understand the science yet. Clearly hi-fi is not perfect. Perhaps twenty years from now digital amps will reproduce the waveforms perfectly, and my faith in specs will be renewed. In the meantime, as science has proved ultrasonic H.D. has audible effects due to interaction with audible freqs., T.H.D. probably should be renamed total harmonic distortion up to twenty thousand cycles, or T.H.D.U.S.S. (THD using sixties science). How many other sacred cows are flawed? Why is analog experiencing a renaisance? Why do tube amps sound so good? (yes, aside from bass). Clearly Solid State specs better . I maintain the human brain is a thousand fold more complex at processing sound as a PC. The human ear is much more precise than the lab analyzer- partially because it works exactly like the analyzer I use to process my music- my ear!

In conclusion, use specs. to help compare products for final evaluation....but don't try to tell us you can judge two products exclusively on paper.

Hammy: Bob Carver's older design's wouldn't pass the spec test and that's why they don't pass the sonic test either. If you think that they did / would pass the spec test, then you're not interpreting the spec's right.

Having said that, you can believe / interpret things the way that you want, but i've already proven to more than a few here that my interpretation of sonics based on measured performance is pretty close. After all, some of these folks have emailed me with nothing but spec's, yet i was able to describe to them what they were hearing, why and how to at least partially correct it. I've also made similar statements publicly about a couple of different amps, their sonic traits and their lack of ability to integrate into various systems. Others that own / have owned those amps supported those comments. The comments that i made were based on interpretation of technical data derived from test results. I'm not saying that everyone can do this, but obviously, some folks can do it better than others. Sean
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