How close to the real thing?

Hi Frank, opamps usually have much lower propagation delays than power amps do! So feedback is more effective with them.

To improve the effect of feedback and decrease the resulting odd ordered harmonic generation, decrease the propagation delay of the circuit.

Irvrobinson, while our amplifiers tend to have higher output impedances, that impedance curve is nearly identical to the frequency response curve of the amplifier, IOW linear from 2Hz-100KHz.

The system was entirely solid state. The format was a digital reel to reel, 1/2" wide. I really did not hear the system, it was only the experience of the music. So what would it have been like if it was 2" analog with my amps on each speaker? Hey, maybe it would have been better.

Atmasphere, I'll admit I don't quite know what to make of this. Although I respect that you have sufficient confidence in your design approach that you feel your products could ALWAYS make a subjective improvement over anything else, it seems that your judgement (or at least your recollection) of this particular experience is totally dependent on your knowledge of the technical matters of its presentation.

This is what I would call a "Maggie Blackamoor" conclusion, after the character on Little Britain: http://www.youtube.com/watch?v=hUpHDtpoY9w

But since I brought up the subject of scientific philisophy (and also to avoid at least a bit of the well-trampled "NFB argument" road). . . to be a bit more precise this would thought of as a plainly "coherentist" argument. That is, the truth or validity of a given conclusion is based upon how coherent it is with an existing perspective or set of beliefs. For the coherentist, the method by which a theory is refined (made more precise) is when data is presented that incoherent with the current belief system, the belief system is revised to restore coherence with new data.

But the logical problem is obvious, it's the same with all theories of justification: it fundamentally relies on one's intellectual "concience" to formulate ideas that evolve beyond one's own belief system. In the field of audio this is particularly problematic, becuause our understanding of many of the perceptual and psychological mechanisms lags far beyond our practical understanding of the physical science on which our technology is based . . . technology that we so routinely use to (attempt to) fool these perceptual and psychological mechanisms.

But we can also see from this line of reasoning that the traditional audio "objectivist" arguments have NO better grounds in modern scientific practice than the "subjectivist" . . . they are both in actuality simply "justificationist". It's simply that "objectivist's" belief system usually can't include a reality outside simple regurgations of common-practice electrical analysis found in an average undergraduate EE textbook, and the "subjectivist's" belief system is so fundamentally undisciplined as to be able to include some really silly, wacky sh*t.

"Irvrobinson, while our amplifiers tend to have higher output impedances, that impedance curve is nearly identical to the frequency response curve of the amplifier, IOW linear from 2Hz-100KHz."

And how does that 4ohm+ output impedance affect interaction with the loudspeakers, since loudspeakers do not usually have anything like linear impedance curves? Won't this effect the system frequency repsonse? Or are you assuming very high impedance speakers with very smooth impedance curves, like Soundlabs?

Human ears (and brains)are complex sensors and information processors of an order far exceeding science or technologies ability to model exactly.

Given this truth, any hypothesis regarding being able to accurately predict the outcome of an individual's listening experience based on science alone, even in a properly executed scientific experiment or series or experiments, has to come into question.

Irvrobinson,

how does that 4ohm+ output impedance affect interaction with the loudspeakers

As Atmasphere states, provided that the output impedance is purely resistive in nature, that is, it does not behave like a capacitor or coil to any degree over the frequency range mentioned, then its effect will be totally benign. Even if it were ridiculously high, say 100ohms, same applies. All the latter would mean is that the speaker would never get very loud!

I also agree with Atmasphere regarding "decrease the propagation delay of the circuit", this is exactly what needs to be done to allow any feedback to do its job. Some people may not be aware that several highly regarded SS amps consisted of nothing more than an output stage driven by a high quality opamp, with, by normal standards, extremely high levels of GFB.

"objectivist's" belief system usually can't include a reality outside simple regurgations of common-practice electrical analysis found in an average undergraduate EE textbook, and the "subjectivist's" belief system is so fundamentally undisciplined as to be able to include some really silly, wacky sh*t.

Human ears (and brains)are complex sensors and information processors of an order far exceeding science or technologies ability to model exactly.

Agree 100% with both of the above

Frank