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So I was changing a lightbulb last night…

I had just finished listening to a record and decided to change a lightbulb that had gone out directly above my turntable. When I started unscrewing the bulb I noticed a faint buzz coming from my speaker. I then turned the volume way up on my amp and tried again. Turns out the buzzing was happening when my hand touched the metal light fixture, not the lightbulb. 

At first I thought the tubes in my phono stage were picking up an EM field from the light fixture and out of curiosity I grabbed a piece of foil and covered the phono stage and then tried tapping the fixture again, same buzzing. Then I switched the input on my amp to my DAC and tried the tapping, no buzzing. Switched the input back to the phono stage and tapped the fixture, buzzing continued. Then I covered the tonearm with the foil and the buzzing went away almost completely. 

So it appears my tonearm is picking up some sort of signal from the light fixture but only when I touch the fixture. If I turn the lights off there is no buzzing when I tap the fixture. The setup is in the basement and I use LED lights that are recessed in the ceiling and wired to an “LED” dimmer switch. The audio gear is on a dedicated circuit.

Any of the knowledgeable folk on here have an explanation for what’s going on? Doesn’t effect SQ AFAIK since the buzzing only occurs when I touch the metal fixture. Seems odd but I thought it was interesting and maybe a chance for me to learn something from the members. 

I uploaded a video of this happening to Imgur that I’ll try pasting here:   
 

 

Cheers

durte30
musicfan2349's avatar
musicfan2349
242 posts
 

@durte30 DISCLAIMER: I'm  NOT an electrician. Read on at your own risk.

Please don't put a fluorescent bulb in a dimmable fixture. From what I understand fluorescent bulbs are designed to work in a fairly narrow voltage range. You can damage the bulb and perhaps your dimmer.

Through a surfeit of caution I've installed several dimmers and LED bulbs in my home and managed to not kill myself or burn down my home. I like Lutron products as their website has some handy on-line tools for the do-it-yourselfer.

Phono sections tend to be very sensitive to EMI so I'm not too surprised by your experiment. You might talk to an electrician about checking your home's wiring.

OTOH, I'm of the opinion that unless you stand on a ladder touching the fixture while you're listening to music, you might be able to just leave well enough alone. Remember the old "Hee Haw" skit?

Patient: Doc it hurts when I do this. *waves arm around*

Doctor: Well, don't do that! *smacks patient with rubber chicken*

Happy listening. 😉

durte30 OP
17 posts
 

@designsfx they are just normal light fixtures that used to have incandescent bulbs. The LED’s I got were advertised as an incandescent replacement that fit that socket type. I did put in a fluorescent bulb but only briefly and then removed it.

@musicfan2349 yeah I don’t plan on listening while touching the light fixture haha but now that I’ve heard the buzz I can’t un-hear it and will probably just put a normal switch in soon.  

jonwolfpell
408 posts
 

You can’t use a dimmer for fluorescent fixtures 

harpo75
107 posts
 

For AC filtering of the light something of this nature might work. They need to be wired inline to the dimmer switch.  These particular ones are way more current then you need but I was looking up units that would cover at least 2-1/2 amps for my needs. 
https://www.digikey.com/en/products/detail/schaffner-emc-inc/FN2090A-6-06/1997013?s=N4IgTCBcDaIGIDkwAYCcyCCBaAbF5OIAugL5A

Or this:

 

 

vinylandtubes
49 posts
 

Off-topic, but do you use your turntable immediately adjacent to your speaker?  If so, then I would anticipate experiencing problems much more significant than this finding.

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