C4 value in the Snarkdoodle

[midwayfair]

Obviously, lowering this cap is part of turning it back into a fuzz.

I was out of 100pf caps and used a 120pf cap instead, thinking, "oh, it'll just make it a little cleaner," but it also appears to have thinned out the sound a little - it's a little brassier that the other Llama I build. I wouldn't have thought this would have this effect, or if anything, I would think it would be the opposite and it would have made the pedal darker. Does anyone have any more info on what, exactly, this cap is doing? Should I desolder it and sub in, say, a 68pf instead?

I looked at the datasheet for clues, but I really didn't undersand what pins 5 and 4 were doing in this chip.

[mgwhit]

The IC is comprised of six two-pin inverters.  I tried to find some info on how these amplify a few weeks back, but came up empty.  I assume they're being (mis)used as inverting amplifiers, but I'm not sure how to calculate the gain.  The bypasses are obviously negative feedback loops, though, so the larger the cap you put in C4, the more treble you cut.  When I monkeyed with it on my breadboard, I felt like it actively boosted bass, too.

P.S. I posted some stuff previously about the bassiness of the circuit, but as I was pulling components from my breadboard for my build I realized that I had put in at least one incorrect cap value.  I decided to just build to Red Llama specs (except an audio taper Gain pot) and I love it.

[midwayfair]

The IC is comprised of six two-pin inverters.  I tried to find some info on how these amplify a few weeks back, but came up empty.  I assume they're being (mis)used as inverting amplifiers, but I'm not sure how to calculate the gain.  The bypasses are obviously negative feedback loops, though, so the larger the cap you put in C4, the more treble you cut.  When I monkeyed with it on my breadboard, I felt like it actively boosted bass, too.

P.S. I posted some stuff previously about the bassiness of the circuit, but as I was pulling components from my breadboard for my build I realized that I had put in at least one incorrect cap value.  I decided to just build to Red Llama specs (except an audio taper Gain pot) and I love it.

See, this is what I expected. The datasheet has them all as "in"s on the 1-8 and "outs" as the 9-16s. I would have expected the larger cap to make it less treblely, like you said.

I'll give it another go tomorrow when I can turn up the pedal. I seem to remember the Llama really disliking the volume not being turned up, and it's such a loud pedal that I couldn't give it much of a test right now. It's definitely brasher than the last one I built, but I suppose that could be any number of components being off.

Thanks for your help. Your posts have helped me understand a lot of circuits a little better recently.