The unit is typically quiet and then today i started getting this random hum every min or so. I disconnected the effects loop to see if that was the culprit but it keeps happening. any ideas?
Hi @Stratman74 welcome to the forum,
It just could be a noisy tube because you mentioned that nothing has changed in the setup’s connections. Hum can be a ground loop so simplifying the setup and removing FX helps debug that.
If you have a spare 12DW7 (ECC832) then you could swap one in. If that does not help, then it’s worth looking at a replacement set of 6550s.