Why do neons in mains plugs/extensions cause so much noise

It’s just one of these things that hopefully an engineer can explain

I had a few of these in various 3 way plugs and extensions, and as I removed them the sound got much better.

Why do they cause quite audible sonic issues to hi-fi components?

My understanding is that any electrical discharge is a source of broadband interference that is radiated through the open air surrounding the source, and conducted through wires attached to the source. Not only does this put an interference source at the heart of your power distribution system, the pulse nature of the neon means that it cycles too. I suppose that the audibility of the interference depends on the design of the hifi power supply section, but many people would agree that it does mess with the SQ

Is it the same with led lights ?


Some LED lights, and all the fluorescent lights I’ve come across, are quite electrically noisy. Whether or not that noise couples into your HiFi is another matter, but I spent some time checking all the light fittings we have, and managed to source some electrically quiet LEDs which I now use pretty much everywhere.

That type of low pressure neon discharge lamp doesn’t conduct until the voltage exceeds 90V, at that time it suddenly switches on and starts to conduct. It’s the edges of this switch on / switch off behaviour on each + & - cycle of the mains that causes the interference.

@Xanthe! Is EM waives the main evil or Mains pollution or … ?


An LED (light emitting diode) such as we have in the Naim panel buttons do not emit noise, these are in effect just a diode in series with a resister.
LED lamps such as we have to illuminate rooms are powered by an integral SMPS & do emit noise, some are better some worse, most modern types do not cause interference with audio or similar.


Ha ha! Full explanation please!

Both mechanisms are possible, which one is more significant depends on the item that’s being affected by the interference.

I replaced all my cheap power strips with surge and LEDs that power things that have to stay on with ones that don’t 1 - 2 years ago. We are mostly Philips LED now. The florescent bulkheads are usually off if listening as are Phone chargers if not charging. Prevention. I’m not sure if I can tell if these nasties are on though. It may be cumulative.


I have only halogen lamps at home, bar a strip on the kitchen.
At work leds, once, i had a painter with it’s own radio, with leds lights on the ceiling the reception was heavily compromised.


It should depend on the quality of the LEDs and the quality and characteristics of the electrical installation; I have LEDs throughout the house, both ceiling and in the bulbs of the lamps, and I did not appreciate any interference or effect, nor with the two large air conditioning appliances, nor with any other electrical device or appliance. However, all HIFI systems are powered from IsoTek strips, of different qualities but all with electric and RFI filter; although there were previously no interference problems, the introduction of the strips has been an important leap forward in SQ on all systems.

This topic was automatically closed 60 days after the last reply. New replies are no longer allowed.