The Role of Negative Feedback

The use of negative feedback has been a point of controversy since the Seventies in amplifier design. In Chapter 24 of Designing Audio Power Amplifiers its pros and cons are discussed and some of the myths and misconceptions surrounding its use are addressed.

My general philosophy is that when it is used properly, negative feedback vastly improves an amplifier, both sonically and in measurement. Unfortunately, there are those who do not know how to use it properly. Negative feedback has gotten a bad rap from bad designs. It is certainly possible to design a horrible-sounding amplifier with negative feedback, but that is also so with no-feedback designs. Indeed, the well-intentioned approaches that some people use to reduce negative feedback and/or increase open-loop bandwidth sometimes compromise sonics and performance. In other cases, the mis-use of NFB can lead to certain forms of amplifier mis-behavior under some conditions, an example being bursts of parasitic oscillation under conditions that were never tested on the bench.