Modification help - Purple Peaker booster

[Smaug]

Hello,

I've finished building my first stompbox, it's Purple Peaker bass/treble booster. I've used the schematic from tonepad:
http://www.tonepad.com/project.asp?id=48

When I've tested it on clean channel it gives quite a boost, both to bass and treble, in a desirable range. However when I tried it on dirty channel with humbucker pickup on my Affinity Squier Strat It seems to boost more bass/mid frequencies and it doesn't sound that great. I would want to modify it to boost more lower frequencies. The treble boost on dirty channel gives a nice boost for solos, I wouldn't change that.

My question is, what parts should I change? I am not very experienced with electronics, but from what I see from the schematic, I should change values of resistors or capacitors near the Lo switch. What values do you think would achieve lower frequencies?

Thanks

[slacker]

Welcome to the forum

There's some information here about lowering the LO frequency, http://www.home-wrecker.com/peaker.html
Looks like they've doubled the value of C4, C5 and C6.

Hope that helps.