In Ceiling Speaker Installation Hum Issue (Not even Connected!)

[PilotMarky]

Fellow enthusiasts... I have an issue with a speaker that I am installing for upgrading to Dolby Atmos. It's a B&W CCM683 ceiling speaker. Unfortunately, when I cut the hole in the ceiling (aligned with other pre-existing ceiling speakers), right above it are a load of mains wires running through the joists. One of these feeds a light attached to a Ceseta Wireless Lutron Dimmer. If the light is on, the speaker hums even without a connection. When the light is off, the speaker is quiet. Clearly, the dimmer is emitting noise, which appears to be quite common.

I have put a mains tester to the wires to see if power still exists when the light is off, and I cannot find any difference between light on and light off.

My next question would be, is there a way to shield the speaker from the cable(s) that are causing the noise? If not, the next step will be to replace the dimmer with a regular on/off switch.

Thanks for any advice!

Mark.

 

[WaynePflughaupt]

I’d say try shielding the electrical wire, not the speaker. Try wrapping it with aluminum foil where it’s near the speaker, and for several feet on either side. Might sound silly, but pro audio installation-grade signal cable uses a foil shield, and the shielding is practically 100%. Can’t hurt to try. After wrapping, I’d also ty-wrapping in maybe 12” intervals, to ensure that the foil stays tightly in place.

Regards,
Wayne A. Pflughaupt

 

[Alex2507]

If the light is LED, Amazon says the dimmer "Works with compatible dimmable LEDs". It also works with incandesant and halogen.

 

[highfigh]

Fellow enthusiasts... I have an issue with a speaker that I am installing for upgrading to Dolby Atmos. It's a B&W CCM683 ceiling speaker. Unfortunately, when I cut the hole in the ceiling (aligned with other pre-existing ceiling speakers),right above it are a load of mains wires running through the joists. One of these feeds a light attached to a Ceseta Wireless Lutron Dimmer. If the light is on, the speaker hums even without a connection. When the light is off, the speaker is quiet. Clearly, the dimmer is emitting noise, which appears to be quite common.

I have put a mains tester to the wires to see if power still exists when the light is off, and I cannot find any difference between light on and light off.

My next question would be, is there a way to shield the speaker from the cable(s) that are causing the noise? If not, the next step will be to replace the dimmer with a regular on/off switch.

Thanks for any advice!

Mark.

Connect the speaker cable's positive and negative wires and try it again. If the hum stops, it will probably be OK when connected to an amplifier. If the woofer magnet is extremely close to the bundle of wiring, move the speaker- there's no easy way to shield it from the magnetic field. Mu metal is OK for low level fields, but not for this. You could try it, but that stuff isn't cheap.

Magnetic shielding is very different from RF shielding.

 

[Montucky]

Just learned that 3M makes a variety of shielding tapes! That could be an easy way to wrap the cabling up with some shielding material. Wonder how well this stuff works.

 

[highfigh]

Just learned that 3M makes a variety of shielding tapes! That could be an easy way to wrap the cabling up with some shielding material. Wonder how well this stuff works.

What are you shielding from, EMI or RFI? The copper foil with screen is great for RF, but it doesn't do as well with EMI. MuMetal is used for that, but even that has limits and it's no picnic working with sheets of it because it's not only thin, it's also stiff. That makes it dangerous to skin and wire insulation. Neither choice is particularly inexpensive, either.

In this case, if it still hums when the amp is connected, increasing the distance between the interference source and speaker(s) is the easiest and best choice.

If you want a fun experiment in frustration, buy an '80s Chevy Celebrity and install a Pioneer AM/FM/cassette deck and see if you can find a way to eliminate the buzzing.