MiniBoosters - FET Boosters (Question)

[Oliver]

Hello,

can anybody tell me, how to tweak those FET Boosters to Mid, and/or Trebleboost ?

Which cap is responsible for the resonance frequenzies??

thanx and bye
Oliver

[Dragonfly]

Hello,

can anybody tell me, how to tweak those FET Boosters to Mid, and/or Trebleboost ?

Which cap is responsible for the resonance frequenzies??

thanx and bye
Oliver

there is no "single cap" to tweak...all circuits are different....we'd need to know what circuit youre thinking of building in order to make suggestions....

[Mike Burgundy]

In general though,there's about 4 types of cap (generalising heavily here) you'll encounter, two of which are interesting.
1) big electro types (10u and up) in the powersupply. Used for filtering hiss, hum, ripple and sag out of your voltahge supply. No effect on sound unless you do something wrong (again, this is a generalisation but it'll do).
2) tiny caps in a negative feedback loop or to mass (picofarads). These are to filter out Radio Frequency (RF) noise. No audible effect.
See, caps are high-pass devices: this means that above a certain frequency their impedance goes down radically, while below it it's pretty high. This point's position depends on the cap's value and the surrounding impedances. A large enough cap with high impedances will effectively be full-range (cutoff frequency is below what you use for signal)
A cap to ground shunts away higher frequencies, a cap in series with the signal line lets high frequencies through and blocks lower ones.
So:
3) caps to ground with moderate values (couple of nano to several hundreds) - for filtering out nasty shrill sounds and
4) caps in the signal line - these block lows somewhat, and let through highs. If used on an input of a distortion, the decreased low content makes for smoother distortion, and if chosen right, *more* percieved bass (think about it: all tghe highs get squashed by the clipping, the clean bass then gets lifted back up again...) This is what a tubescreamer does.
Note: there is a sort of
4b) - same thing, *but in a feedback loop": now everything that the cap lerts through is deducted fron the signal, so the whole thing works the other way round....
see what you can figure out with that?