So I was recording today and my amp started making popping noises, which I thought was a bad cable or jack. So while I'm wigging the cable around trying to find the problem, the cracking and popping started getting louder and louder until all of a sudden my amp just started squealing at full volume and I couldn't make it stop, I had to put it on standby. Now every time I turn on the amp, that's all it does. I found a video of Mark Tremonti having the exact same problem on stage:


It sounds just like that. This massive feedback squeal at full volume. Does anyone know what causes this in Mesa Rectifiers and what I can do to fix it?
-Mesa Dual Rectifier (3 Channel) with KT88 and KT66 Tubes
-Peavey 6505+
-Roland JC120
-Ibanez Tone Blaster TBX150H
-Mesa 4x12 Straight Cab
-Marshall 1960BV
-Gibson Les Paul Custom
-Gibson Flying V
-Line 6 M13
It's a microphonic tube, probably a preamp tube.
Gilchrist custom
Yamaha SBG500
Randall RM100 & RM20
Marshall JTM45 clone
Marshall JCM900 4102 (modded)
Marshall 18W clone
Fender 5F1 Champ clone
Atomic Amplifire
Marshall 1960A
Boss GT-100

Cathbard Amplification
My band