Voltage divider question

[Big Monk]

If you’re talking about the output pot at the end of a gain stage, I don’t think that’s completely accurate. The output impedance of a gain stage is determined by the circuit topology. I believe a fuzz face has a common emitter at the end which has Rc as output impedance. As long as Rc is smaller than the volume pot, it is the dominating output impedance and the frequency response will be the same. I would be surprised if Rc were not much smaller than 100K, in which case 100K vs 500K won't make an audible difference (the frequency response will be slightly different but probably not to our ears).

I don’t believe the output impedance of the Fuzz Face factors into the high pass filtering formed by the output capacitor and the volume pot.

 

[Big Monk]

I am not sure I follow what you mean here? I think the volume and tone pot are actually more interactive in a guitar wiring than in a pedal because there is no gain stage preceding them: the output impedance of the pickup determines the frequency response and "loads" the pots. This impedance is usually much higher than most gain stages, and higher for humbuckers, which is why we usually use higher pots with humbuckers.

Edit: the guitar tone pot is usually (non 50s wiring) one side of the pot in series with the cap, both in parallel with the volume pot. At very low volume the interaction between the three components and the pickup impedance has a substantial effect on high frequency content, which is why when you lower the volume on the guitar you lose some high frequencies (unless you use a treble bleed).

The point being made was that lowering the volume pot in a pedal circuit often raises the apparent high frequencies getting through to the output.

Raising the volume pot in a guitar raises the apparent high frequencies getting through to the output.

You can decide why this difference exists but to me it’s the difference between the high pass filtering in the direct signal path in the output cap/volume pot combo of the guitar pedal vs. the issue of reduced loading in the guitar circuit.

 

[giovanni]

Oh I see what you mean. The thing that threw me off is that you have a high pass filter at the end there, so all high frequencies are retained. The volume pot value will affect the high pass cutoff, i.e., the low frequency: lower pot value, less bass through the output, which can be equivalently perceived as more highs. I was looking at this article to get my thoughts straight here