I'm putting the parts together to build this in the next couple of days and was wondering about the bottom 180p cap in the switched tone control. It's in parallel with a 10n cap and adds less than 2% to the 10n. Won't this just be swallowed up by the tolerance of the 10n?
I'll probably just leave it out but I wondered if anyone had experimented and found any noticable difference with or without this cap.
You're correct. The 180pF at the bottom can be omitted with no ill effects. We left it on the schematic for the sake of authenticity.