Does it effect to sound of the BSIAB if I use a 47nf cap in the place of C4,C12 or C14? and if it effects, how?
Janne
Maybe/probably ... depends on the original values on the schematic, what the %age difference is, what they do, etc.
C4 is the coupling cap between the first two stages. C12 is the coupling cap between the 2nd and 3rd stage. Increasing these from 22n to 47n will let an octive more bass through. But since these act on the signal before all the distortion is made, they'll change the character of the distortion. Maybe 'farty' or 'flabby' sounding. Try it and see.
C14 is part of the low-pass filter at the output of the pedal, made up of R17, C13, R18 and C14. They're to reduce the fizz from the distortion and more closely simulate the treble response of an amp and speaker. Making C14 bigger will let less treble through.
I built a BSIAB2 using the GGG layout and the specified parts, though I did audition a few different JFETs in Q5. I'm very happy with it. Sounds terrific with a bridge humbucker. If there's any place where I'd want to mod it, it would be the tone control.
I'd stick with the values Ed Guidry chose for the BSIAB.
The gain is very near the edge of feedback in that circuit, adding bass = added gain.
Thanks for anwering, My problem was I thought that I don´t have three 22nf caps, but I found one. Sorry that it took so long to answer back to you, I had a huge troijan horse problem yesterday.
Janne