Signal path and voltage path. Where I end and you begin

[nonost]

 Hi. I like to use different electro caps for signal and voltage path. Also it's a good idea to use metal film resistor in the voltage path for those buildings with carbon resistors. But being honest I don't really know where the voltage path ends. In this example (easy circuit for purpose):



 I would say that the 22k is voltage path only. And no electro cap in the voltage path. But another question comes to my mind. The 10k, 1n cap, 200R and 100uf cap aren't in the audio path, are they? So these resistors could be swap for metal film resistors for better accuracy and low noise?

I'm not trying to open a metal film vs carbon resistors. Just would like to know how to mix them properly.

Thanks!

[Travis]

Good Radiohead song :)

Caps block DC. You should have some voltage present on every part but R1 and the two pots

[nonost]

I was typing the subject and that song came to my mind...and had to do it. I've always liked that bass line. Such a sinister song for rainy evenings in your bedroom.

Mmm, that's true. Maybe I haven't explained myself well. If I'm not wrong, there are "two" kinds of electros: ones for psu purposes and the audio ones. Even if that thing doesn't really matter for analog guitar pedals I like to use them that way. But I'm not sure if I'm doing right.

The same for the resistors. Even if you want to build a board full of mojo carbon comp resistors it's a good idea to use metal film for those resistor that aren't in the audio path. Is that right? Well, I would say that all resistors are in the audio path but the 22k. But now I have my doubts about the resistors to ground...

Anyway, thank you Travis :)

[Travis]

Different resistor types have other differences beyond their thermal noise which can come into play. Carbon comp resistors have lower induction which can be useful. Also doubling the size of the resistor cuts the thermal noise in half. Since many people use 1/2W carbon comp resistors instead of 1/4W metal film in pedals the difference in thermal noise may not be as significant.

In either case I would say that the difference tends to be pretty insignificant in stompboxes

The only electro cap here is the “bypass cap” which is not directly in the audio path but is used to increase the gain of that transistor.