• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

Transformer Hum.

I've assembled my power supply chassis for my new TSE 300B Amp. I'm getting a little buzz from my Power Transformer. It's bolted down tight to a 1/4" aluminum top plate on a wooden chassis. Should I try loosening the screws holding it down? Put some neoprene under it? What should I try? I can't hear anything while music is playing, but when it's not, and I get close to the amp, I can hear a little buzzing. Thank you all very much.
 
Two problems that can cause the buzz. One; you have unbalanced mains, i.e. there is a DC component on your mains. Second: if it is an e-core and the buzz is sharp mechanical then dip the transformer in varnish. Final thought, if the amp is standing on a big hollow cabinet then it can be minute vibration coupled into the cabinet amplifying the buzz. Try isolating the amp from the cabinet.

Good luck