Current amp vs Voltage amp

Bifwynne,

What you relate sounds fine and does not surprise me. Whatever the details, paying attention to impedance matching between components pays off. Its a fundamental thing to get right, sometimes harder than others.

I just do not buy into the assertion that power paradigm and no negative feedback is the only way to make music sound real. It is based on sound theory perhaps, but in practice is not consistent with what I have heard in both cases over the years.

Cheers!

I just do not buy into the assertion that power paradigm and no negative feedback is the only way to make music sound real.

That's fine but it will not change the reality:

The problem here is that the human ear is more sensitive to odd ordered harmonics than almost anything else. Add on top of that that the ear is most sensitive at higher frequencies (FWIW the human ear is tuned to be more sensitive to bird song frequencies, something that comes from our forebears as a survival trait); the result is we can hear odd ordered harmonic content that is hard to measure on the bench.

We constantly hear how the ear is insensitive to this or that (for example we cannot detect the phase of a sine wave at all) but this is certainly an exception, and for a very good reason: the ear uses odd ordered harmonics to figure out how loud a sound is. This is vital to our survival- if you can't figure out how loud certain sounds are, you might soon be dead!

The thing about negative feedback is it does two things- one thing we like, the ability to servo-control the output of the amp so it will produce flat frequency response on *certain* speakers. The other thing it does is reduce distortion overall while actually adding odd ordered harmonic distortion.

When you add odd ordered harmonics even in trace amounts, it is audible because of what I have already explained. The result is it won't/can't sound real. You don't violate a fundamental human hearing perceptual rule without a price!

Get rid of the feedback get rid of this problem! But now you have to sort out how to get flat frequency response and low distortion without feedback. There are ways to reduce distortion, but how do you get the flat frequency response?

Use Power Paradigm design rules.

Many speaker designers do this, whether consciously or not, depending a great deal on the sort of amplifier that they like to listen to.

The Voltage Paradigm will work fine if you can build an amplifier that is simultaneously free of odd ordered harmonics and can also behave as a voltage source. That is the leading edge of the envelope in amplifier technology; so far no-one has been able to do it. There are some very notable amplifiers IMO that point the way- Ayre, Pass and I am also a fan of Berning, although the latter might be considered more of a hybrid approach. I suspect class D has something to offer here as well.

Ralph,

Yes I know and you are very consistent in communicating the principles you design from and execute accordingly with your products, which I have heard sound pretty darn good.

But as I said its not the theory I have problem with, but the fact is that what I hear otherwise does not support it, and I do not think I am alone.

Its not that your way is a not a good way, I accept that it is, but the proposition that it is the only way or even the best way these days in all cases is debated.

Ralph does have some very valid points. For example it is believed that language evolved from "bird sounds" if that makes sense(prehistoric dialect)? Children are more sensitive to higher frequencies and sounds than adults, you can claim a part of that on desensitization/acclamatization etc. But it was a very specific purpose ... survival. Females like childeren are more in tune with their senses all for survival.
Plenty of research on this on the medical aspect.

However I'm wondering if one could near completely eliminates "any" distortion, as seen a few of the newer class D, is it possible to bypass the odd order issue?

It appears that most of us here agree the ultimate quest is sound quality. Which ever technology approach that gets you there, so be it.If someone truly believes a particular class D amplifier is equal or surpasses the sound quality of a tube amplifier with NFB absent then case closed, you've found the right amp for your needs. I've yet to experience this result and find the class D examples I've heard so far inferior in realism and natural sound.So newer technology withstanding, some older ideas and designs simply stand the test of time and at least to some listeners are the superior choice for sound quality. So it's good we rely on our ears regardless of what measurements and new technology may promise in theory. The audio marketplace caters to all the various preferences we have, choice is good.