BSIABII Tweaking

[mremic01]

I've built three BSIABII's and they all sound a little different. Two were on perf and one was the GGG kit, which is my favorite pedal by far. The one I put together most recently is pretty close to the GGG one, but it sounds like the tonal character of the pedal is shifted down a little bit. It has more bass and less highs. It doesn't get quite as searing on the leads like the GGG one does. I'd like to tweak it to get it as close as possible to the GGG one so I can stick it in a multi-FX unit I'm working on. I have 2 J201s and 3 2n4547s just like the GGG schematic calls for. I socketed the two .0022uf caps near the output, but removing them only seems to make the circuit way too fizzy. Both are biased to about 4.5v.

The only real difference between this perfed circuit and the GGG one is that I used a silver mica 470pf where the GGG one has polystyrene, since I'm having a hard time find polystyrene caps in that value. Would that be noticeable? Should I try messing around with cap values or could it be the transistors? I don't really want to cut bass so much as shift the tonal focal point of the circuit higher all around.

[Ice-9]

It's more likely the jfets, Jfets have a large tolerance difference in manufacture so just swapping them for a different one (like for like) can give huge changes in sound. I have built BSIAB's with poly, ceramic or mica caps but the biggest difference in sound has been the selection of Jfets.