I wanted a "different" tone control for my
Low Gain Amp. By combining modified BigMuffPI tone with modified Marshall bass amp MID control I got this:
Sounds nice. Gives bass/treble tilt and variable mid scoop. For nearly flat response (3dB mid scoop at 540Hz) set TONE to 1 o'clock and MID to full value. Change C23 to 2.2n for less than 1dB scoop. If you try this in your amp please let me know how it works for you.
Pekka