I have experienced what seems to be RF Noise that is generated from LED lighting.
I don't have the exact spec's but just wondering if anyone here knows of what to look for as to packaging labels or spec's on LED lighting, if any.
The issue just came up today when talking to a customer that has just recently had LED lights in there bar. He says now there is noise that is being heard on the background music speakers it the area for the customers.
I can speculate a lot of thoughts on why and how this happens but, would like to know the opinion from the masses here.
I did not install the lights or the audio system. Just trying to understand and possibly come up with a solution.
Leds work on 2-3 volts and they use switching current regulators to limit current to the leds. Anytime you switch power on and off abruptly you create electrical noise.
To ameliorate the situation it could be as simple as grounding the lamp housings, or running the wires away from the music system, plugging one or both into different electrical sources. A ground to the music system may help too. If it only has a two wire cord a ground to the chassis may work.
Or adding some filtering. A common mode filter is what is usual. Some are as simple as a clam-shell style ferrite core around the wire feeding the lamps, or a wired in power line filter.
When it comes to filters they are way more effective at the source of the noise than the device affected by the noise.
I had a situation where turning on compact fluorescent lamps (back in those days) would trigger my passive IR sensor - small filters in every switch box fixed it. Ditto my electric range would cause my dial-up modem to crash, a humongous big filter fixed it.
Most designs today are better than that. A different current limiter for the leds may work, but switching outlets is easy to try and those clam-shell ferrite chokes take very little effort to apply. (close to the source of the noise since the wires act as antennas and radiate the noise out from them) Running the power cable through a ferrite donut with a few turns around the core is another approach to filtering.
Buzzing implies a noise source with sharp rise/fall (as opposed to hum (sinusoidal noise) or white noise (like a water fall) or low frequency "pumping" sounds etc.
In the audio range, and if it also happens to be the same as the line frequency...
Obviously in the audio range.. but some RF comes across as distortion in music sources, not something you can quite describe but it shows on a scope as parasitic oscillations in the rise and or fall in the music transients.
Often the sound can give some clue to that is happening. A buzz at
60/50 cycles per second (line frequency) should be easy to quench, and I'd lean more towards a lack of a ground somewhere or a ground-loop and not something a filter can fix.
Well it seems the speaker buzz was not due to the newly installed LED lights. Owner got to playing around with various other equipment and determined that when the Comcast Modem was unplugged the buzz stopped. Somehow they came up with a Ground Loop Isolator device and installed it on the cable and another Ground Loop Isolator device at some other point near the amp and the buzz is gone.
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