Hey there, I'm sure there are tons of posts on here to cure hum problems, while I have found one or two threads of these, the search feature makes it impossible to search for the word 'hum' being that its under 4 letters. (This a very stupid search parameter IMO, I'm sure we'd all be very happy if it was removed) Anyway, This is a new bandmaster 5e7 clone. I have tried everything within my limited knowledge to alleviate this hum. The amp hums without the guitar plugged in, both gain knobs all the way down. I have replaced all of the tubes, one by one. I have double checked the schematic with the amp. All of the connections seem to be correct. I used metal sheilding on the back panel, even tried grounding it the chasis, no help. I made an audio file so you can hear the hum. http://www.atundra.com/ampnoise/ Hear's what you are listening to: I used a very noisy Gibson Skylark from the 60's as a basis for comparision. It hasn't been maintained in at least 10 years and still has a two prong plug on it. I figured this was a good base example for noise floor on vintage amps. Most people's amp are in this condition. Ok, the audio file is sliced into 5 sections, with a bit of silence in between. These are how the slices are divided up: 1. Microphone on and recording, no amp on. (This shows the nominal mic preamp hiss) 2. Gibson Skylark on. Gain know at zero. No guitar plugged in. 3. Bandmaster on. Both gain knobs at zero. No guitar plugged in. Presence, Treble, Bass all set at 12 o'clock. 4. Gibson Skylark on. Gain set at 9 o'clock. Guitar plugged in. 5. Bandmaster on. Gain set around 8 o'clock on Bright channel. Guitar plugged in. (the last two tests are not totally fair, because I couldn't match the gain of the amps exactly) Things to note: I didn't change any mic preamp settings or move the mic at all between sections. I used the same speaker for both tests. It was rated the correct imnpedance for both amps. The guitar being used has humbuckers, to help rule out single coil hum. Hopefully this audio file will provide some clues to some experts as to what it might be. And you can also see that the hum is definitely pretty excessive, even for a vintage amp build. I am very friendly with a soldering iron and I am open to any suggestions for adding/removing components. Thanks!