big hum when switching the EQ

Hello,

it's been a while since I came here, I'm trying to find someone to 'repair' my head but first I want to know if someone has an idea.

Last year I changed all the tubes! thinking it could end my troubles…

But when I switch the EQ on there is a big hum like when u got to cable touching or something (just the idea) I think something might have died as when I plugged my ADA preamp in the return I had a big screaming high noise. (don't know if it's related)

any idea?

thanks

hi,

the EQ circuit is designed around 4 transistors , i bet one could be the culprit, leaking current to ground

thanks for the info