Help Needed: Detecting High-Pitched Whining from LED Bulbs – Best Mic & Setup?

[theREALdotnet]

The only association I can draw between high-pitched whine and LED lights is that when I switch on the latter my wife will notice the new audio component(s) I bought without telling her...

 

[DonH56]

I have replaced a few LED lights that have whined enough to be annoyingly audible. If they are audible it probably does not take a fancy mic. I would be more worried about a consistent test setup. My advice would be to use UMIK-1 sealed (taped, whatever) into a tube (paper towel, heavy cardboard, PVC pipe, etc.) so you can press it against the light for the tests. I would open the light end of the tube to help pick up noise emitting from the base (where the whining power supply lives). Use REW or other SW to run an FFT so you can see both the frequency and relative amplitude for different bulbs.

Something like this:

FWIWFM - Don

 

[Chrispy]

My first thought was dimming circuits rather than just a typical bulb but don't have them in use generally when using audio/video gear.....might have to experiment with that but at that range will need a mic

 

[bothu]

UNIK-2 is much better than UMIK-1 regarding self noice.

 

[Blumlein 88]

UNIK-2 is much better than UMIK-1 regarding self noice.



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It is, but I think the real issue is the Umik 1 is using a 16 ADC internally.

 

[itchaboyagain]

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I’ll have to look into this building a chamber could be a fine side project once I have some glorious time

 

[Timcognito]

I’ll have to look into this building a chamber could be a fine side project once I have some glorious time

Some rigid panels, saber saw hot glue gun and you are there for with/without test run.

 

[itchaboyagain]

The Lewitt is not only low noise, but about among the most sensitive. Those are the two things you most need.

The free software is pretty easy to learn. You might want to read up on FFTs if that is not something you are familiar with. High count FFTs let you look well below the normal noise floor. It is something REW and Multitone let you do. The people who wrote both are members here.

As for calibration an advantage of the Umik 1 is it is self calibrated in REW. As they are less than $100, I might suggest getting one of those and see how far you can get in your testing with it. Then if you later go with a better microphone this one can be used to calibrate the other microphones for SPL. You also might want to get it from Cross Spectrum labs as they calibrate them more carefully. While not the most sensitive or lowest noise the Umik 1 is good enough if the noise is loud enough to be heard you'll likely pick it up. It does have some noise spikes in its noise profile that might be an issue, but still pretty cheap to take a first shot at it without spending too much.

Interesting! Thank you for this information

 

[itchaboyagain]

UNIK-2 is much better than UMIK-1 regarding self noice.



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Awesome! Thank you for this comparison.