Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: ElPedro on February 28, 2016, 01:33:54 pm
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Working on a Splawn Nitro head for a buddy of mine. His complaint is that there is a ton of hum in the amp. There sure is! He said this problem started sort of suddenly.
There is no hum in the amp with power tubes out, so I don't think the hum is being generated directly by the output transformer. The hum gets louder as you turn up he volume and add in gain stages.
I have tried different power tubes (he's running 6l6), and different preamp tubes. The bias is sitting at about 72% dissipation.
I tested all of the filter caps and they look good. They are within about +6% or lower of spec.
a visual inspection of the other components didn't reveal any obvious issues.
I had to hit the road for a business trip before doing anything else, so I thought I'd run this by you all and see if you had any ideas.
Thanks!
ElPedro