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RFI from steel TV bracket?

Yesterday I installed a new TV on a steel wall-mounted extendable bracket between all my electronic components.
I now have a low hum/buzz from both speakers on all sources....even with the preamp on mute?
When I switch the preamp off.....the hum is still there.
The only way to remove the hum is to switch the amps off?
I tried grounding the steel bracket to the preamp and then the amps without success.
The previous TV was in the same location but sitting on the shelf.....not a steel wall bracket.
Any help would be dearly appreciated?
halcro
theaudiotweak
2,801 posts
 
Ground loop from your cable tv or sat box. Unhook the coax cable from the source tv direct/cable box or sat and turn everything else back on and take a listen. Tom
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theo's avatar
theo
2,706 posts
 
If I understand this you just installed the TV mount onthe wall. Is there any chance a screw cut into your Romex in the wall and is hitting a grownd wire? I would say try removing a screw at a time and check for the hum. It just odd that an LED Tv is doing this or that the metal mount is causing it.
halcro's avatar
halcro OP
2,664 posts
 
I unhooked the cables from the cable TV......no change.
I then suspected the 2 metre long Cardas cable interconnects running on the shelf behind the TV and just under the steel brackets and plate.
The right-hand interconnect runs right across this 'field' before dropping down to connect with the speaker....whilst the left channel interconnect runs for only a foot before dropping down.
The left speaker only emits a light buzzing whilst the right speaker has the definite 'hum'.
So I wrapped both interconnects in aluminium foil and this reduced the level of the hum and buzz.

Not knowing much about electricity.......is it possible for the steel bracket combining with all the power outlets directly below it, to create an electro-magnetic field which the long runs of unshielded interconnects then acts as 'antennae' for the RFI/EMI?

If this is indeed the problem.......would going to fully balanced XLR interconnects, solve it?
theo's avatar
theo
2,706 posts
 
What all do you have connected to the TV? Are you using a Pre-pro that you can connect everything to then just run HDMI from the Pre-Pro to the TV? If you are running analog IC's to the TV and they are picking up interference from the AC cable then maybe a shielded power cable would help. If possible try to have your analog IC's cross the AC cord at a 90 degree intersection, if they must cross. If they are coming out of the TV mount area and must be together, try sheilding them as much as you can.
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