I am getting a high pitch squeal out of my amp but only in the OD1, and OD2, channels in anything above green channel. Tubes have checked out fine. I am using a pedal board through the FX loop but I also use a Voodoo Labs isolated power supply. And I have pulled each pedal out of the loop, one at a time to see if it was a specific pedal that was causing the issue. Still squeals even without pedal board. It is becoming frustrating to try and determine what the issue is. Any suggestions or advice?
You will get feedback when using the high gain channel, make sure you are not standing to close to the amplfiier as this will increase the feedback, we would also recommend checking the pre amp valves to make sure one isn`t microphonic.