boosts, drives, and tone stacks

[nag hammadi]

i am looking at some of the simple passive tone stacks around. 

in general, if i were to tag one onto a boost or overdrive, is it better to do i before or after?

[d95err]

It depends a lot on the type of booster or overdrive of course. The safe bet is to put the tonestack after the boost/od. In particular, you need to control the overtones (treble) generated by distortion. If you generate a lot of distortion, you will also want to control the amount of bass going into the distorsion circuit. In either case, you'll need some fixed freqency shaping both before and after distortion.

For a single knob tone control, the typical solution is a variable lowpass filter at the end of the circuit. For a two knob control, I'd use a bass control before distortion and treble after.

[Hanglow]

I think the ROG Tonemender is a passive one with a boost, have a look at that. I'm always using mine

[nag hammadi]

oh yeah... i didn't think about splitting them up. 

i was thinking about the one knob fat fuzz and the fire starter as candidates for experimentation.  i am a bit hyped on the fire starter with a simple eq and a boost in front all in one unit.  i was thinking the lpb in front, then fire cracker, then eq.  do you think i should do a 2 band with the bass between the lpb and the fire cracker and the treble at the end?

i usually like to keep things really simple, but this one is a departure from that for experimentation.

[Mark Hammer]

Tonestacks work by selectively bleeding signal to ground.  Consequently, if you stick a tonestack before a booster, you can be boosting residual noise more than signal.  At the very least, the S/N ratio is not as good as it might be with the tonestack following the booster.  Though I suppose one might look to the BMP and ask "Well if they stick a transistor gain stage after the tone control, what is so wrong with doing it myself?".  The answer to that is that the recovery stage after the tone control is simply meant to make up for what you lose through the tonestack, and pales in comparison to the gain applied before the tone control.

Now, if you  want to use variation in bass levels of the input signal to alter the drive quality of the booster, it might be better, and less problematic to simply have a switch-selectable input cap value for the booster, then use the tonestack after the booster stage to adjust to taste.