I have searched and cannot find exactly what my problem is. I have and SVT Classic with 8x10 and a Pbass. When I am playing sometimes the sound will start to distort for 10-30 seconds almost like I am running it through a distortion or fuzz pedal and then go back to normal. I changed out the speaker and instrument cables and still have the same issue. I cant replicate by any specific means it just happens out of the blue. The bias is set to green on both lights after the amp has warmed up and has no signal running through it. Current EQ Settings: Gain 5 Bass 6 Mid 8 Freq 3 Treb 7 Master 4 Thanks for any suggestions on what this may be.