RFI from steel TV bracket?

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.

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?

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.

Halcro, it really sounds like you may have created a primitive power transformer with your wiring setup. If that is the case, the metal frame is acting as the core and the speaker leads draped over it are the secondary.

Try re-routing the speaker leads.

Hi Ralph,
The interconnects were running under the steel bracket.......not draped over it.
The speaker leads are on the floor well away from the bracket (as they have always been).
I just re-routed the right channel interconnect to along the floor away from the steel bracket........but the hum is still there?
Again.......if I run in fully balanced configuration from preamp to amp......shouldn't this prevent any RFI/EMI interference?
Isn't that why all professional sound systems run in this way?