DirtDawg
Ex Member
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One of my SB84C units, all are original as far as I know, has developed a hum.
I might not have noticed it, but the unit that is in question is mono-ed across my lows. Yeah, I hear hum. HOnestly, it is tiny, but if my old "deafened by thirty years of rocknroll ears" can hear it ten feet away, then it surely means I have an issue.
It is very minor at this point. I thought I heard it a few days ago, but as I have begun to test things, I definitely have a hum, which I can move from side to side, depending upon how I hook up the amps.
I have replace all the tubes, even subbed in known good tubes from amps that did not hum.
I KNOW that this is new. NO, really, I would have noticed this before. This IS new.
On another note, I have already replaced all my power cords, all my inputs, I have gone nuts lifting grounds and even left this unit ungrounded and grounded, with every thing else lifted.
I have unplugged everything, gone straight to speaker from cd player with only the amp in the circuit, then just shut everything down, unplugged everything and with just the amp running with shorted inputs across a speaker, I have a hum.
Any other ideas, guys?
I know that these ten year old, second hand amps are not something that Steve will want to have to deal with, but I am losing my "magic time."
Any help would be greatly apreciated.
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