I've not done this mod on this circuit, so it is better to socket the referenced component positions in case it doesn't work out.
The orange distortion uses a modified big muff tone control. The typical mid range control for this circuit is based off of Jack Orman's "new AMZ Tone Control":
http://www.muzique.com/lab/tone3.htmTo complete this on the orange distortion, do the following:
- Change the tone pot to a B100k
- Change R15 to a 39k
- Change C11 to a 100n
- Replace R24 with a 25K pot
The new 25k pot becomes the mids control. There are other ways to do this, but these values should work very well.