Overdrive/Distortion Tone Questions

[aziltz]

I've noticed that a lot of different designs have two things in common: Tone Control or Stack and some Fixed Filtering.

Think of a TS vs a BSIAB.  Fixed Filtering + Tone Control in a TS, Tone Stack + Fixed Filter on Output in BSIAB.

when you guys "design" an overdrive, do you incorporate the taming of the clipping harmonics *IN* the Tone Controls/Stack, or do you think of it more as setting a "preset" voice with fixed filters and adding/subtracting from that for "Tone" Control?


I realize this is very open ended, I just wanted to hear some opinions from people who tinker a bit.

[aziltz]

anybody?  i was hoping to get at least some discussion.

[anchovie]

The BSIAB2 has filtering in the gain section too. You've got a high-pass filter formed by the R/C combination on the source of Q1 and the resistors and caps that couple the gain stages will form filters too. I believe the fixed filter on the output is supposed to be the world's simplest speaker simulator.

Personally when I design distortions I also take the approach of concentrating on the filtering in and between the gain stages. I see the tone stack as a way for the pedal to be adjusted depending on the amp it's running into, not the main way of voicing the dirt itself.

[aziltz]

Personally when I design distortions I also take the approach of concentrating on the filtering in and between the gain stages. I see the tone stack as a way for the pedal to be adjusted depending on the amp it's running into, not the main way of voicing the dirt itself.

you're very right.  I left that out of the original post for a reason...i think .  As I understood it, that's best used for controlling what frequencies will get clipped. (ie, cutting bass before clipping).

I think i'm wondering more about ways to tame the harsh harmonics associated with clipping.  (ie, if you took the signal straight from the ouput of the Tube Screamer's Clipping Amp, very trebly, very harsh).

[kvb]

what I've gathered from reading here and looking at schemes is that when it comes to distortion there is a need for both kinds of filtering: pre and post.

Mark Hammer writes about keeping things nice by taming the high end harmonics in between stages.
There are various ways to do this.
Joe Davisson's overdrives are a good source for multiple stage ideas.

one thing I've found while playing with certain circuits is that even though heavy mid scoop is the "cool' thing for shred type distortion,
one way to get super shred is to boost the mids in a stage then cut the mids at the end.

This gives tons of distortion etc without shrill treble nastiness.

Another avenue is to use feedback (+/-) to control some frequencies