How close to the real thing?

"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

Irv raises a good point about the interaction of high amplifier output impedance with speaker impedance vs. frequency variation. An OTL amp having a 4 ohm or other comparably high output impedance will not be a suitable match for some speakers. See Ralph's Competing Paradigms paper for additional discussion of this subject.

Regards,
-- Al

Kirkus, I think you missed my point! The quote you put up is edited and not what I said. Try re-reading my post, without the idea that I am trying to make you wrong- that was not my intent at all.

Irv, maybe you were joking but Sound Labs have anything but a flat impedance curve. Just because a speaker has a variable impedance curve does not mean that an amplifier with a high output impedance cannot drive it well, without tonal anomalies. It is all in the intention of the designer, as the article that Al linked points out.

A vital point here is that distortion in amplifiers and speakers is perceived by the ear as a tonality, and without this understanding that tonality won't get measured. This is close to the heart of the subjectivist/objectivist debate. Once you understand how the ear/brain perceives things, a lot of this debate goes away.