90% of hum gone but why???

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As some of you know, (and were kind enough to give me advice), I was having a hum problem with my DIY SV83 amp. On and off for the last week and a half I have been unsoldering and resoldering every ground wire on this amp. I have tried every groud scheme I know of and all the variations I have read about on this forum to no avail. I tried adding capacitance to the filter and tried different filter configurations also but this didn't help either. Today I noticed that when I tied the safety ground to the circuit ground the hum increased but I had no idea why. Disregarding this I proceeded to install a hum pot in the filament circuit just for the heck of it. So I ground the wiper to circuit ground and I then tie safety ground to circuit ground and 90% of the hum disappears. The thing is I don't have a clue why and was wondering if any of you with lots more experience than me could tell me why this happened. Listening through a 105db horn I can't hear any hum at a distance of maybe 1 foot from the speaker now. I used to be able to hear it from a listening position 6 feet away! By the way, adjusting the hum pot has absolutely no effect on the remaining hum. Thanks,
Jim

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Topic - 90% of hum gone but why??? - breadhead 15:32:43 04/15/07 (4)

Was there any ground connection on the filaments ... - Triode_Kingdom 08:07:58 04/16/07 (2)

Re: Was there any ground connection on the filaments ... - breadhead 11:46:58 04/16/07 (0)

And didn't you say it hummed even without the output tubes? - Triode_Kingdom 08:15:00 04/16/07 (0)

Re: 90% of hum gone but why??? - Michael Samra 23:38:40 04/15/07 (0)

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