Hum from Flourescent lights?

Posted: Mon Jun 02, 2008 9:15 am

We are getting a small hum/noise on our wireless mics intermediatly. We have Flourescent lights in the Sanctuary and stage area at this moment. Is there any thing we can do to stop this/cut it down for the time being until we get stage lights?

Posted: Mon Jun 02, 2008 9:19 am

http://www.sdltd.com/_tutorials/noise_cancellation.htm

Posted: Mon Jun 02, 2008 9:35 am

Greener wrote:

http://www.sdltd.com/_tutorials/noise_cancellation.htm

I don't want to sound like an idiot but that is way over my head. I understand about the different frequencies of sound/noise and all but I have not gotten that in depth on this subject.

Posted: Mon Jun 02, 2008 9:36 am

They sell hardware that does it, and many other people make software that does it.
It is noise cancellation.

Posted: Mon Jun 02, 2008 11:08 am

Uhhhh...:S

What hum is it. Low end hum, hissing, general blasts of sound?
See if you can make a recording of the hum you get and see it with a spectrum analyser. This may help - if it's one specific frequency you can cancel that one band out.

Are you sure it's the lights? Turn them off and does it stay or go?
Also I think you mean "intermittently" and not "intermediately", not that that matters.

Also, having not come across this problem myself, is it audible noise from the lights that is the problem or electrical interference?
I'm asking only because we don't have any fluorescent lights near our wireless system, however there is one near the mixer and I hate the noise it makes.

Posted: Mon Jun 02, 2008 11:30 am

Codemonkey wrote:

Uhhhh...:S

What hum is it. Low end hum, hissing, general blasts of sound?
See if you can make a recording of the hum you get and see it with a spectrum analyser. This may help - if it's one specific frequency you can cancel that one band out.

Are you sure it's the lights? Turn them off and does it stay or go?
Also I think you mean "intermittently" and not "intermediately", not that that matters.

Also, having not come across this problem myself, is it audible noise from the lights that is the problem or electrical interference?
I'm asking only because we don't have any fluorescent lights near our wireless system, however there is one near the mixer and I hate the noise it makes.

It is like electrical interference. It only does it around the ballast areas of the lights. The lights have a slight hum to them also but not one that is noticable unless everything is really quite.

Posted: Mon Jun 02, 2008 11:56 am

The ballasts need replacing.

Posted: Mon Jun 02, 2008 1:09 pm

They dont necessarily need replacing. ALL flourescents hum including the newer electronic ballasted ones. It is a Bflat in case anyone wants to know.....They hum because of the construction of the metal frame and the fact that the ballast is simply screwed to this without any dampening at all. There are completely quiet flourescents but these are quite expensive and doesnt solve your noise in the sound system problem anyways.........this is caused by the fact that they fixtures are heating a gas with a high-voltage being induced by a ballast which causes a harmonic peak in the power supplying these fixtures and is unfortunately picked up by sensitive electronic gear in the vicinity.

One method is to remove the sound system amps and board from the circuit supplying the power to the lights. Or if this is the case already, then you must determine if they are on different phases of the power panel. If they are on a different phase...ie: 'A', 'B', or even 'C', then they need to be on the same phase as the lights but not the same circuit.

Posted: Wed Jun 04, 2008 11:36 am

What RF mic are you using?

Where do you have your receivers? How far away from the transmitter?

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