Hum from Flourescent lights?

Discussion in 'Location Recording' started by Cmac3469, Jun 2, 2008.

  1. Cmac3469

    Cmac3469 Active Member

    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?
     
  2. Greener

    Greener Guest

    http://www.sdltd.com/_tutorials/noise_cancellation.htm
     
  3. Cmac3469

    Cmac3469 Active Member

    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.
     
  4. Greener

    Greener Guest

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

    Codemonkey Well-Known Member

    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.
     
  6. Cmac3469

    Cmac3469 Active Member

    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.
     
  7. taxman

    taxman Active Member

    The ballasts need replacing.
     
  8. Davedog

    Davedog Distinguished Member

    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.
     
  9. sheet

    sheet Well-Known Member

    What RF mic are you using?

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

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