I own a Peavey ValveKing 212 combo, and recently got a Dunlop Crybaby 535Q. So I've been playing with it, and I notice this red button the side labeled "boost selector." Having never played with it, I decide to push it into the "in" position. As I do, my amp lets out an increasingly loud ear-piercing screech, getting louder untill I unplug the pedal (which I did A.S.A.P).

This also happens when I use one of the distortion settings on the Dan Donagan (or however you spell his name) Signature pedal. The only difference is the distortion pedal lets out a higher-pitched screech, while the wah pedal lets out a, still very high pitched, but lower pitched scream.

What could be the cause of this? The peavey is hardly a month old, and the tubes still glow as they should, so I wouldn't suspect that- But I wouldn't rule it out since I'm no expert. Any suggestions?
There's a volume control for the boost on the left side of the pedal. Try adjusting the volume level, it's possibly up too high.
it's ,called feedback, it's happening because the volume or distortion level on the padals are to high so if you turn them lower it will go away.
Quote by steven seagull
Can I save money by using lightbulbs instead of tubes - will energy saving lightulbs last even longer?

Quote by latinosuperstud
if i buy a les paul studio and walk out into public a man in a clown and/or gorilla suit named tyrese, will come attack me and/or rape me