Power Amp transformer hum - intermittent and increases and decreases in a few seconds

john_simp OP22 posts

03-13-2019 2:17pm

I don’t have a multimeter. This is my basement Home Theater and I do have cheap LED light bulbs in use. I turned them off to see if I still get the hum. I’ll check it over the next few days to see what happens. Yes, that’s the picture of the amp.

You can pick up a descent Fluke multimeter at HD for $50.00.

I would suggest you turn off the breaker that feeds the wall outlet that feeds your HT system and see what all is on the same circuit.

The circuit could also be part of a 3 wire multiwire branch circuit. (The device causing the DC offset could be on the other circuit and traveling on the common, shared, neutral to the outlet that feeds your HT outlet. Nothing more than just a guess though.)

Your situation can be solved by having a new 20 amp dedicated branch circuit installed. You already have discovered the amp doesn’t hum/buzz if plugged into an outlet in another room.

Cost? Depends on the distance from the electrical panel to the new outlet, and the wiring method needed/used because of the basement wall and ceiling finishes. Example, is the ceiling drywall? Is the wall the outlet will be on wood stud with drywall?

Usually electrical wiring estimates are free. YMMV though where you live.
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Ken:  yes, very frustrating. Hum is just coming from transformer. 

Jea48:  thx for ideas. I'll look into them.