In article , ebyea wrote:
It's for a guitar tone control and I'd like to replace the little 0.1mF
marked 104 light dull brown about 3/8" circular cap with a paper in oil
which I happen to have or a hovland or something of a bit more quality.
Would there be any loss of signal using a different type of capacitor
or is a cap a cap and all that matters is the rating and that the volate
meets or exceeds the requirement?

Passive, a very loose word. There has to be some electrical activity in there.
Is this a tube amp? An external line stage? There is voltage rating to
contend with. Different caps can have different effects, but those effects
are also dependent on the circuit.

greg