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Author Topic: Noise Problem - Possible Power Issue? or Gain Structure?  (Read 8135 times)

Jonathan Johnson

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Re: Noise Problem - Possible Power Issue? or Gain Structure?
« Reply #10 on: March 13, 2011, 09:04:36 pm »

How convenient: an article on exactly this topic, posted Friday 3/11 on ProSoundWeb.

http://www.prosoundweb.com/article/church_sound_files_audio_gain_structure_for_wireless_microphones/
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Karl Winkler

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Re: Noise Problem - Possible Power Issue? or Gain Structure?
« Reply #11 on: March 14, 2011, 01:24:10 pm »

Except that Mr. McQueen said:
This seems to indicate that it may not necessarily be a gain structure issue at the transmitter. If the receiver's output is set too low, then you'd be turning up the input gain on the mixer, and that could be where the noise is coming from -- in the mixer's preamp (it could be faulty). Mr. McQueen hasn't returned to tell us if he's done any other troubleshooting.

It would be interesting to know if the noise goes away when unplugging the cable from the mixer.

I'd put my money on the gain difference between the receiver outputs (set too low or attenuated) and the mixer inputs (too much gain to compensate for the low receiver outputs).
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Aaron_McQueen

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Re: Noise Problem - Possible Power Issue? or Gain Structure?
« Reply #12 on: March 14, 2011, 10:12:56 pm »

Sorry to keep everyone guessing, I did some more testing tonight.  I'll be able to do a little more Thursday.  Here is what I found.  It seems the noise is not related to the wireless units at all, and I can reproduce the noise on any of the mixer channels even with other instruments, mics, or DIs connected, by turning the gain to the same level on those channels. So it seems this is a problem further down the chain or with the board itself.
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Mike Spitzer

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Re: Noise Problem - Possible Power Issue? or Gain Structure?
« Reply #13 on: March 14, 2011, 10:25:07 pm »

Cool. Then it seems some of the other guys were closer than I was.

Take a look at the signal indicator on the receivers when somebody's into the mic. If the signal looks low, then that's causing you to turn your gain up too much on the board. Just turn up the gain on the body pack until the signal looks better on the receiver and you should be good to go, assuming there's not a real problem somewhere else.

I'm pretty sure somebody else said that up there somewhere, but I didn't want to re-read the whole thread. =)

-mS
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Kent Thompson

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Re: Noise Problem - Possible Power Issue? or Gain Structure?
« Reply #14 on: March 15, 2011, 03:18:47 pm »

Sorry to keep everyone guessing, I did some more testing tonight.  I'll be able to do a little more Thursday.  Here is what I found.  It seems the noise is not related to the wireless units at all, and I can reproduce the noise on any of the mixer channels even with other instruments, mics, or DIs connected, by turning the gain to the same level on those channels. So it seems this is a problem further down the chain or with the board itself.


It still could be that you don't have enough gain coming from the wireless units. If your having to open your gain so high that its making noise you need more level into the board. I would start with the microphone set its gain to where you get as much signal without clipping as you can then do the same with the receiver. You should be able to lower the gain on the board then which should make your noise go away.
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Aaron_McQueen

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Re: Noise Problem - Possible Power Issue? or Gain Structure?
« Reply #15 on: March 15, 2011, 03:43:40 pm »


It still could be that you don't have enough gain coming from the wireless units. If your having to open your gain so high that its making noise you need more level into the board. I would start with the microphone set its gain to where you get as much signal without clipping as you can then do the same with the receiver. You should be able to lower the gain on the board then which should make your noise go away.

Thanks Mike and Kent, I'll try this out on Thursday.  I seem to remember the gains on the wireless being good, but I'll check to make sure.  Right now I run them between -25dB and -30dB. Also according to the manual concerning the PAD: The PAD will be internally switched on or off when the HA gain is adjusted between -14 dB and -13 dB. Keep in mind that noise may be generated if there is a difference between the Hot and Cold output impedance of the external device connected to the INPUT connector when using phantom power.

I'm pretty sure that phantom power is not enabled on the mic channels.
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Tim Padrick

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Re: Noise Problem - Possible Power Issue? or Gain Structure?
« Reply #16 on: March 20, 2011, 01:45:49 am »

If we run the audio output levels of our EW100G3 too low and then crank up the preamps to compensate, we get some nasty noise.

If you are feeding them into the mic inputs, make sure that phantom power is off, as many devices behave oddly when they see phantom - even things that should be designed to deal with it.
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