new amp build
ss rect, 47uF first filter cap, 220 ohm "sag" resistor.
amp sounds fine when you first turn it on... after about 5-10 minutes one channel starts to hum kinda loud. other channel is quiet (but has a lot less gain).
where to look?
what could cause this?
Moderators: pompeiisneaks, Colossal
Re: what could cause this?
Considering the power supply can take up to 10 minutes to stabilize, I wouldn't even start troubleshooting for the first 5 minutes.krash wrote:new amp build
ss rect, 47uF first filter cap, 220 ohm "sag" resistor.
amp sounds fine when you first turn it on... after about 5-10 minutes one channel starts to hum kinda loud. other channel is quiet (but has a lot less gain).
where to look?
I'd start by looking stage by stage for grounding issues. Check out the voltages on all plates and cathodes, plus look for stray DC voltages at locations where there shouldn't be any.
Can you post pictures of the grounding scheme? IME hum, especally if it comes from only one channel, is caused by ground loops.