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Amplifier Hum - Only Amp Connected

I have read many threads on here about various amplifier hum.

I recently bought a used tube amplifier.  When I connected the amp and turned it on, I immediately heard a hum from the mid-range driver of both speakers. The hum is audible even if the pre-amplifier is turned off/muted. In fact, I unplugged all interconnects from the amplifier and still heard a hum when the amp was on. I then unplugged the the interconnects and unplugged everything else in the room from the outlets (turntable, pre-amplifier, TV, and cable box), so that the only thing in the room connected to the wall was the amp. I still hear the hum from the speakers when it is only wall>power cord>amp>speaker cable>speaker.

This has to mean that it is a problem internal to the amp, correct?
jdpawnbroker

Showing 2 responses by jea48

jea48
4,734 posts
 
Does the hum sound like this?  
120Hz hum.   

https://www.youtube.com/watch?v=pC4Uzt0qm2E  

If yes it could be failing electrolytic caps in the power supply. 

How old is the amp?

Manufacturer and model?

jea48
4,734 posts
 
jdpawnbroker OP6 posts

12-13-2019
5:33pm

Cheater plug did not make a difference. Hum was still there.

Did you put a piece of tape on the bottom of the cheater plug ground tab, or over the trim screw that hold on the electrical outlet cover plate, so the ground tab does not make electrical contact with the metal screw?
The trim screw is electrically connected to the equipment ground.
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