Historical look at amps

Unsound,
Read your post.
My post WAS NOT an attack on any person or persons. LET ME MAKE THAT CLEAR if it was not.
2ndly, I NEVER meant to say that my choices are better than yours (Unsound) or anybody elses. Let me MAKE THAT CLEAR as well, if it wasn't. (I should know better than that!)

You, Unsound, might not have been brain-washed by the marketing dudes, which is probably good for you. My statement was a general one. Most of the people fall for the marketing ploy & you often read posts supporting the marketing propaganda. Of course, there are people who have learnt & know better than to succumb to it.

Indeed what sounds "correct" to me might be/will be different from what sounds correct to someone else. I do find, however, that the longer a person stays in this audio hobby & gets many chances to hear diff gear & make direct comparisons of s.s. vs. tube gear in the same system, the better are his/her chances of realizing the positive attributes of linear amplification devices over non-linear ampl devices. That person might still not want to own tube gear - fine! - but the realization does set in.
This point might have been missed by you?

I don't know of any designer that looks to feedback as a solution to bias stabilisation in a SS amp. Lowering noise, distortion and output impedance, yes. Increasing bandwidth and input impedance, ditto.

Maybe the guys who design tube gear do, but I don't hang around with any.

But since this was supposed to be about a "historical look at amps", and feedback...........let me ramble on some about the stuff that I have done.

Mid 80s.......overall feedback, but much less than usual. Maybe 10-20 dB.

Late 80s.....no loop feedback in the voltage gain stage, loop feedback for the outputs. (Similar to Stasis.)

Mid 90s.......no loop feedback anywhere.

Early 00s........"digital" amps. Tons of loop feedback.

Looks like we have come full circle.

Bombaywalla, perhaps the point was missed by me. As far as realization, others may indeed come to the same conclusion and others may not. How ever I think it important to realize that our systems are complex and some attributes of sound that may be particularly pertinent to an individual may be better served due to technical or budgetery needs to use certain components that that may be better served by alternate means of amplification. Just so we undertand each other, I don't take any personal offense by your opinion. I just thought that another perspective was in order. Best Regards.

We may have come full circle but that circle has some waves. For example, one of the more respected SS amps that has received great reviews is the Parasound JC-1's. Well, guess what, it has 30db of GLOBAL feedback! (and to me, it sounds like it---it's soundstaging is relatively 2 deminsional) Global feedback is being used more than you think. Ayre, Theta, some Pass and maybe another or so don't use global feedback. It's still fairly uncommon. These amps have higher distortion values and are generally lighter in the bass than higher FB amps. They act somewhat like a tube amp and clip similarly.
I agree completely with Bombaywalla. Marketers try to influence you with BS but it is up to the individual to educate themselves. All designs have tradeoffs. As one remains in the hobby, your tastes with change---usually with age. There is no doubt in this "Old fart's" mind that no global feedback amps offer a higher level of sonic purity (and notice here I didn't say anything about sounding better---that's for you to decide.) If you listen to voices and instruments, you'll find a higher level of natural sound.
I played sax for 30 years and I can tell you without hesitation that the low feedback (0 GFB) amps sound more realistic (they may not meet the dynamic criteria or impress with a "Balls to the wall" sound some favor.) They are certainly not for everyone. I can also say GOOD tube amps are even closer. They offer that special bloom but not all. Some are noticably soft and bloated. I think the perfect amp would be tube mids and highs with SS bass.
I always thought the "High end" was about accurate portrayal of a source. If it's not and it's about "Good sound" then I need to get out because it all becomes a moot point. There's a huge difference between what offers good sound and what is an accurate portrayal of the recorded venue. Some stuff just doesn't sound good and shouldn't sound good.
So much equipment is offered because of the tastes of the individual. However, some of it is wrong and a little of it is right. It does take years to figure a lot of this out. I've been at it 35+ years and it is amazing how my tastes have changed since the beginning.
BUT---to each his own! Everyone knows what they like.
With all that said, I will add one last thing. It is my held belief that some of the differences in sound of no feedback and feedback amps is do to time domain distortions created by out of phase global feedback---but this is a discussion for another day.

I don't know of any designer that looks to feedback as a solution to bias stabilisation in a SS amp. Lowering noise, distortion and output impedance, yes. Increasing bandwidth and input impedance, ditto.

I agree. Feedback is not used for bias stability in transistor or for that matter tube amps. There are numerous stable bias schemes for amps and they don't involve feedback.

Some amps use DC servo control to maintain zero potential at the output of a push pull amp to avoid using coupling caps. This might be interpreted as feedback since the output potential is monitored, and a correction voltage fed back to a prior stage, but this is usually not considered as feedback since it works well outside the audio band, and is used for an entirely different reason than those listed above.

Still no response from Ayre on my inquiry about their claim of zero feedback.