Microphonics, Feedback and Bob Carver

First, I’m going to present a theory I don’t have a lot of investment in, I’m just curious about.

Bob Carver and I, at different times, have wondered about the ability of an amplifier’s feedback circuit to be impacted by a speaker’s natural microphonic attributes. That is, in a room and unplugged to an amp a speaker and microphone are broadly similar. A diaphragm is exposed to sound which moves a voice coil which generates an AC signal in proportion to the acoustic event. Of course, a speaker is a terrible microphone, but it can be one.

The question I’ve had, and then read Bob Carver also asked (but he’s not known for always being right, nor am I 😁) is whether part of the problem with negative feedback in an amplifier is that it can pick up in room sounds (such as from the other speaker) and react to it in a negative fashion.

While this is testable via equipment I don’t have, not to mention time/energy to do it right, I’m wondering if anyone has ever read any more on this subject they’d care to share?