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Old 1st Jan 2012, 12:18 pm   #3
Michael Maurice
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Join Date: Feb 2006
Location: Wembley, Middlesex
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Default Re: Akg c60 valve mic

Is it mains hum, ie 60Hz or 120Hz or a higher frequency?

I dont know this particular mic but assume (maybe wrongly) that heaters are DC, if not then there could be some heater/cathode leakage.

If mains hum then try smoothing capacitor.

If not then check all other capacitors especially paper ones.
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