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Hum in Speakers with New Dedicated 20 amp Circuit

I just ran some 12-2 from a new 20 amp breaker and installed a dedicated outlet for my system. Now I get a very audible hum in both channels. If I switch back to the shared 15 amp outlet, no hum. I checked the new outlet with a tester and it checks out as wired correctly. At the electrical box, the black wire is connected to the breaker and the white and ground are attached to the same ground strip. I’m using a 20 amp receptacle.

Anyone with thoughts on how to resolve?

mjjw
invalid
1,073 posts
 

If his sub panel was installed years ago, isolating neutral did not apply at the time.

erik_squires
15,657 posts
 

Welp, I thought this requirement was a lot older, but per this discussion, 1999 was when the requirement changed:

 

 

erik_squires
15,657 posts
 

Also, while we are at it, looks like you have mixed brands of breakers in there.  The breakers have to be either of the same manufacturer as your panel or specifically rated to be in that panel. 

Make sure you use cover plates for any holes in the cover.

vinylshadow
400 posts
 

/Possible ground loop. Do you have a digital processor? Try cheat plugs on different components. 

ieales's avatar
ieales
1,201 posts
 

mjjw: "The sub panel has been in for almost a decade."

The panel is illegal.

Insurance companies love illegal and uninspected installations 🤑

 

 

 

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