What is wrong with negative feedback?

Negative feedback has been used in amps for a long time but the use got out of hand in the 1970s when the "spec wars" got going big-time. Amp designers found they could get very low distortion numbers which looked good in magazine ads.

The catch is these spectacularly low distortion numbers were measured with a static signal. Music is a dynamic, constantly changing signal. After a while, people discovered that the correlation between a very low distortion number and how the amp actually sounded in use was a bit more tenuous than first thought.

Amp design is a balance of competing factors; feedback is only one aspect of that equation. The key is to find the best overall balance for the amp in question. Using zero-feedback. when it is the subject of tunnel vision focus that ignores other parameters, is not a sole guarantee of performance any more than the mindless pursuit of super-low distortion numbers was 30 or 40 years ago.

I think you will find the answer to your question if you read about amplifiers by Soulution. Apparently, their research showed that in conventional amplifiers, the negative feedback that was applied was slightly out-of-time with the signal it was trying to correct, therefore throwing off the coherence of the original signal. I remember years ago hearing a similar criticism of the servo systems in Velodyne subwoofers. Anyway, they supposedly found a way to corrrect that problem, and I think that it is their position that negative feedback is not a bad thing when it is implemented in the way that they do it. The only bad thing is the price of their amplifiers...whew!

There's open loop (global) and closed loop (local). Few designs can be stable into low impedance loads without some feedback and, if you read carefully, some advertise "no global feedback" and sometimes forget a word. In the case of op-amps, it's usually already there.

Easy to find all the negative things about negative feedback. I'm still waiting for someone to advertise positive feedback as being better :)

What about feed Forward ?