I have an annoying hum in my stereo pultec, it's around 80-100hz and comes up after a few seconds, when the tubes had lighten up...
the pin1 of both input xlr is connected to ac ground, to the groundplanes on the board and to the chassis... (the same as starground ?? )
all pin1s of all xlrs arec onnected together
both trafos are packed in grounded aluminium boxes to prevent magnetic interferences...
so do you have any idea what could be the reason for this strange hum...
maybe bad parts??
my main trafo makes a little noise itself, when it gets power
my tubes are valvo nos e88cc
???
thank you
mat