How can I add a Big Muff mid boost/cut switch to a Timmy?

[GrooveChampion]

Which of the caps is responsible for the middle response?

Pardon my ignorance in advance.

[nocentelli]

There is a bass control and a treble control: Both act as "cut only", i.e. cutting the low end below a frequency set by the 1u, and cutting treble above a frequency set by the 3n3: The mid response is a function of the input cap and output cap values, and to get a mid "boost" you would need to cut bass and treble and slightly boost the output simultaneously (and also maybe boost the gain to compensate for the slightly reduced low end content going through the clippers)

[GrooveChampion]

So basically its a hassle.

[nocentelli]

If it's already built, yes it's not an easy "add a pot between these two points" mod. If you've not built it yet, it would not be much effort to swap the second opamp from being a simple buffer for the treble control to being part of an active, three band baxandall tonestack with treble/middle/bass cut+boost controls: The Earthquaker Talons overdrive pretty much IS a Timmy front end with a 3 band baxandall TMB tacked on the end.