by mills » Mon Sep 08, 2008 11:31 pm
Shoot.... had a better reply typed out, and the internet ate it.
I'm a long way from an expert, but here's some of the things I've read a bit about, used in other circuits, and was going to try on this project. Life's been to busy for me to breadboard it, so this is only my speculation for the pedal I was going to try and tweak for bass. Either solder the parts in and sub them out as you try it, or socket them in and its a little easier to play with the values.
The 150pF capacitor between the two transistors... I think that increasing it should filter the highs out a bit, but I could have that backwards. I had thought about increasing that, leaving off the tone control, and putting in a different pot instead for a different control.
C1... Theoretically, increasing this value increases the bass going into the circuit. I don't know if this is calculated to let most audible frequencies through, but it could make a difference. It might not be a noticible increase in lows, as much as the nature of the distortion as different frequencies are clipped.
I've read that increasing the 10uF caps to the ground might increase the lows, but I think I've seen it debated if there's actually an audible difference after 10 or 20uF... Couldn't hurt to try though, and I've seen some bass fuzz schematics that have up to 100uF in a similar position.
There's other possibilities to try, but these are three easy ones. Just try and play around with the values if you can... it gives you an idea how the parts effect the sound.