Put it over your shoulder and pat it on the back.
Tune (Hybrid) preamp Making Loud "Burping" Sounds
My VTL 7.5iii is a hybrid tube/solid state preamp. Lately, it makes loud burping sounds, like what a backfire in a car would sound. I suspect one or both my Amperex Bugle Boy 12 AU7 tubes may be drawing near its useful life or is defective.
Any of my colleagues who could diagnose? I can open the lid and play with the tubes but its a bit of a pain. Thank you. Neal