Our Church uses Yamaha CM 12V speakers for monitor, powered by QSC GX5 amps. Every 3 to 5 minutes once we hear a weird buzzing static noise from the speakers. The noise will be loud, and will last for less than a second. This has been happening for a while now. Can anyone help me to fix it?

Yamaha CM12V - http://www.guitarcenter.com/Yamaha/CM12V-12-2-Way-Club-Concert-Series-Monitor-1274115033579.gc

QSC GX5 Stereo Power Amplifier - http://www.guitarcenter.com/QSC/GX5-Stereo-Power-Amplifier.gc

Let me know if you need any more details.

  • Does it happen with and without sound playing? With no inputs plugged into amp? This type of issue usually means a component has perished. You would need to contact QSC for advice.
    – n00dles
    Commented Mar 14, 2017 at 15:42
  • ye.. it happens even when no sound playing, when all the channels are muted..
    – franklins
    Commented Mar 15, 2017 at 4:31

2 Answers 2


I have figured out the problem. We had a netgear wifi router connected to the mixer. It is supposed to enable wireless connectivity to our mixer. If I turned that off, the mic signal doesnt drop and we dont have the choppy signals any more.

  • Would you care to select this response as the answer for completeness?
    – ZaellixA
    Commented Oct 12, 2022 at 11:58

This is a mobile phone in vicinity to your equipment (including amp, shielded (!) cables, and other stuff). Turn it off. Not just silent (then it will still periodically shout out to its cell phone tower in order to make sure it is still there) but off.

You say "this has been happening for a while now", so it is a safe bet that the phone is owned by someone in your band and is in a standard location with respect to the equipment (cell phone on the body while playing electric guitar is also a real howler, but setting it down in a somewhat sensitive location is sufficient).

There are other sources of noise, but the pattern with which it appears makes it rather likely that it is a mobile.

Another possibility is a fridge or air condition turning itself off. But my money is on the phone.

  • 1
    mobile phone interference is very distinctive, though - and everyone knows the "dit dit dit" pattern. I think you are more likely to be correct with your firdge or AC guess
    – Rory Alsop
    Commented Mar 31, 2017 at 16:03

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