Possible ground loop? What can I do?

B

benracin

Audiophyte
Hi guys, great site. Hope you don't mind a long question from a new guy. I tried to list the things I've tried so thanks in advance.

I've just finished my home theater cabinets and wiring and now all the goodies just showed up. Never had a powered sub before and my new axiom sub has a hum. My equipment is plugged in like so, I also grouped things for the outlet they share.:

1st outlet
Samsung DLP - 3 prong plug

2nd outlet, on a monster surge protector
Onkyo 603 - 2 prong
Phillips DVD - 2 prong
Dish Network DVR - 3 prong

3rd outlet
Axiom Sub - 3 prong

When I'm setting up all my A/V cables if I make all metal connections I get the sub hum. If I isolate the tuner from everything by only using opticals, the sub won't hum, which means I can't run any video through the tuner because those are metal connections and complete the circuit. I can't run a video cable to the tv for the on-screen set up because that causes hum. So if I'm using metal connections I think my ground loop goes outlet > sub > tuner > tv > outlet. If I do anything to break that chain, like unplug the TV, hum goes away.

Unplugging the dish coax connections doesn't make the hum go away.

I've tried hooking the tv up to a different circuit using a long extension cord and that doesn't do it.

The house's panel is grounded by the incoming power line. Does this mean I need a better ground or is there some easier trick I can do? I saw that monster has a special sub power center with RCA jacks on it would that work? I really don't feel like shelling out more Monster money if at all posible. :) Is there something special I can plug the TV into to break the chain?

Thanks guys.
 
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