twin hum question

billy tam R.I.P. · From: baton rouge, louisiana

My 65 twin reissue(90 model) has slight hum problem.
Was working an outdoor show Saturday and noticed it during sound check. Looking today at home the hum was still prsent and seemed to be in the reverb. I checked v3 and v6. V6 had an older jj ecc81 and v3 had a new 12axt7. Left v3 as it was and replaced v6 with another ecc81 that I had and a lot of the hum went away. I noticed that the hum is almost non existent when the vol. pot is on either the low or high end but noticeable between 3 & 7. Is this possibly a tube issue or a pot issue?
thanks in advance,
Billy

Dave Grafe · From: Hudson River Valley NY

Most likely neither, sounds like your reverb tank or the connecting wires picking up noise. Make certain the the bottom of the tank has its metal shield in place.

billy tam R.I.P. · From: baton rouge, louisiana

Thanks
Dave you are probably right. I swapped reverb i/o and have almost no hum at all. I believe it was a combination of an old/bad tube in v6 and the reverse wiring.
Billy

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