Phil Hobbs wrote in
m:

Except for the horrible voltage coefficient. Carbon comps' resistances
decrease by about a quarter at their rated voltage.

Veering swiftly offtopic... this interests me because people often rave about
the sound of valve amps. I don't mean audiophool ravings, I mean those who
like the effect especially in overdriven amps for bass guitar and other
instruments where the sound is appropriate, and very good. It's normally
attributed to the harmonic distortion and saturation effects in the valves,
but now I'm wondering how much of it might be due to that voltage coefficient
in carbon resistors. Maybe designers deliberately tried to reduce the effect
by careful biasing, or maybe there is a strong effect that is overlooked, I
really have no idea...

Comments welcome, so long as they come from either experience or interest in
this subject.