Bogen CHB-50 Rebuild

[physics]

Thanks for the actionable pointers, I'll go start trying 'em and report back. It seems like the general idea is to reduce problematic gain so that moving the guitar closer and "closing the loop" so to speak doesn't result in oscillation taking off. Does that mean all amps couple with guitars like this, and that it's the circuit that determines whether they can handle it, not stuff like whether a transformer needs more shielding or the like?