Not sure if this is the best place to post so I might try another section too.

I installed some ceiling lights that I control with a Lutron brand dimmer. The lights are on a new circuit but the wiring parallels some of the old house wiring that feeds the Onkyo receiver. The dimmer switches the AC voltage on and off very quickly to achieve the dimming effect. It seems this is the root of the problem from what I've read.

The new lighting wiring must be acting as a transmission antenna and the old wiring must be acting as a receiving antenna. I can hear the amplifier buzz when the lights are dimmed. It's likely the power supply inside the unit. I don't think it comes through the speakers but you can hear it coming from the actual receiver box. If I plug the receiver into an outlet on the other side of the room (that is not fed via a wire that runs parallel to the new dimming wires), the buzz goes away but that isn't an option and my room only accomodates one HT layout.

I've done some research and found some "possible solutions" but I suspect somone here may have had the same problem at some point. Anybody have any recommendations on how to clean up the dimming ciruit or otherwise solve this problem?

Thanks

Lutron spells out the bad news about RFI from their dimmers and offers some suggestions for dealing with it, in their FAQ (http://www.lutron.com/service/FAQ.asp) and in this PDF file, http://www.lutron.com/applicationnotes/360476.pdf

Dimmer noise can be both conducted and radiated, meaning that you may have to solve both problems. You've already ruled out one solution. The cheapest solution is to replace the dimmer with an on-off switch.

There are variable transformer dimmers. Not cheap, not pretty, but quiet.

I've used a Ground Isolation Transformer to solve that problem. I used a Tripplite IS250: http://www.tripplite.com/shared/pdf/spec/tlspec_226.pdf

Make sure all grounds are good, especially on Satellite or Cable TV coax cables.

The ground for the Satellite/Cable TV coax cables and the electronics processing the signals from those cables need to have the same potential to earth ground. The satellite/cable TV cables should run through a Ground Block that is grounded from the same ground source the electronics using the satellite/cable TV signals (STB's & TV), which prevents Ground Loop Hum.

Dimmers dump a lot of noise into the Power Line, so filtering and ground isolation is the treatment for Dimmer hum.

Good luck.... May need it for hum problems...

Thanks GWC.

All good advice. I disconnected everything except the actual receiver and TV audio cables. No video or any other components were connected and plugged in. The buzz was still there when the dimmer was turned down to maybe 50% or so. From there it got worse the more I dimmed.

Plugging the receiver into a distant outlet that wasn't near any dimmed romex fixed the problem but that isn't feasible for a permanent fix. Lutron makes a "lamp debuzzing coil" that might help but I'm having trouble actually finding one. They only sell them to distributors and I'm finding they aren't normally stocked and Lutron sells them in cases of qty 10. Doh!

I'll check out your link. Isolation transformers should do it. Other possible solutions I'm thinking about are:

- APC Power conditioner (though I doubt it can filter such quick rise time spikes)
- Using 25W bulbs instead of 50W so I don't have to dim them as much w/ the dimmer. (Not sure this will help enough)
- Finding and installing some type of metal flex conduit over the romex that carries the dimmed current to try and shield it from the rest of the wiring. (not sure if this exists or if it will help enough)
-Variable transformer dimmer. (Likely will work although the seem very expensive too and difficult to find one that's visually acceptable for residential use)
- All else fails - Don't dim the lights. That would suck considering I installed 7 recessed lights to use for "mood lighting". Each spot lights a picture on the wall.

A search on Lutron debuzzing finds some vendors, at $153 and up for the coils.

I've owned Onkyo equipment on and off over the years and have not found them especially susceptible to dimmer noise.

Before you get involved in expensive projects to stop the noise, try some things. First, dimmers vary from unit to unit in the amount of RF they generate; try another dimmer.
Second make certain that the grounding connections on the circuit are good back to the panel.
Third disconnect all of the input cables; the noise entry point might be the TV or one of the cables. Disconnect the audio cables from the TV. If the noise stops the TV is the problem component. If the noise remains disconnect the cables one at a time. If the noise stops try a new set of cables.