I had a feedback switch on a diy twin reverb. Only problem was I had the output xfmr wired wrong so that the switched actually connected positive feedback. So if we were doing a freakout in the middle of a song I could hit that switch and solo over the squealing which did not really go over that well, jus saying...
The amp did have a pot to change the bias as needed for the room.
The amp did have a pot to change the bias as needed for the room.
