Going full nerd on this one, we discuss 3 (sort of 4) types of tone control circuits and how it impacts the sound.
*Bluesbreaker style tone control
*Big Muff style (types 1 and 2)
*Tube screamer style
Buy the book about pedal mods on Amazon: https://www.amazon.com/How-Modify-Guitar-Pedals-how/dp/1434801063