I came across discussion on pros/cons of negative global feedback in SS amp design.
There seems to be 2 camps, first saying that NFB is bad regardless of implementation, mainly for 2 reasons.
One reason being the nature of NFB to increase distortion of odd higher-order harmonics which are objectionable to human ear/brain (what according to them is what contributes to perceived SS harshness in comparison with tube designs typically having low or 0 feedback and generating even harmonics distortion). THD figures do not demonstrate this objectionable distortion according to them.
The other reason being that there is a measurable propagation delay through the circuitry and the out of phase signal (180 degrees) brought back to the input through NFB application smears time domain.
The other camp negates validity of such reasoning, and says that NFB is actually a good thing, when implemented correctly in a good design (not as a fix for poor design), and in this case there is actually no such increase in either even or odd higher-order harmonics distortion, as well as that there is no detrimental (audible) impact of bringing out of phase signal back to the input, when done in moderation.
So what is considered a moderate level of NFB?
Bryston amps apply 30dB NFB, correct?
What is Bryston’s design approach in regard to NFB and what is actually happening with harmonic distortion?
