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I'm having a 'problem' with wireless sets we use. (Sennheiser EW100 G3)

Whenever it's directly connected to one of our ENG broadcast camera's they work just fine. However, when the wireless receiver is connected to my SQN mixer wich connects to the same camera they seem to be a lot more sensetive to interference.

It always starts promising, once turned on; no interference,... yet. But always when we start filming the interference kicks in. It starts with some minimal distortion not even noticable. But it gets louder and more severe after the first prominent interference. Bursts of noise, short gaps with no signal, distortion, etc. Often the interference is loud enough to work the mixers' limiter! Even changing frequencies doesn't help anymore? It's like the wireless set has gone crazy.

I know it sounds weird that the SQN could be the problem, but it happened a couple times before with different EW100 G3 sets, I couldn't solve the interference and switched to the camera's internal wireless Sennheiser EK3041 thinking the problem was with the wireless EW100 G3, or just some RF in the air. But now I'm totally clueless.

Same location, same wireless, same frequency (which should be free according to Sennheiser Frequency app), same input settings (mic, no phantom) the person with the wireless mic is only 5 meters away, the only difference is the mixer!? Because when the problem occured, we directly plugged in the receiver in the camera and the problem was solved. Or is it not a mixer thing but a camera thing?

Any ideas / solutions / workflows or anybody who experienced this before?


EDIT

This is C02sounds, posting via new account. Thanks for the replies NoiseJockey & AJ Henderson

  • Well switching frequencies doesn't help. Like I said, the frequency I'm using should be free according to Sennheiser Freq App. And the same frequency used when directly hooked up into the camera works just perfect.

  • Changing batteries on the wireless set didn't help either.

  • Metal objects around the mixer; RE50 (not plugged-in) in front compartment of a porta-brace, XLR cable for Sennheiser 416 (plugged-in 48v) in CH1, Sennheiser EW100 G3 receiver CH2, there's a small monitor for playback/live view mounted on the bag.

The problem is somewhere in the mixing bag, AJ Henderson you're correct that there are too many variable. I was just wondering if someone ever had experienced this before and could be 'easily' explained. I'll try to recreate the situation again and try to remove/check parts in the chain.

Thanks all for your replies

  • I think it would help if you put up a picture of your bag. Like what NoiseJocky suggested, the position of your gear and type of bag may affect RF spray. – user6513 Apr 24 '14 at 16:01
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Seems like you should start looking at other variables, namely trying another frequency, trying different transmitters (not receivers), changing batteries in one unit at a time, changing locations (I trust that you've checked for presence of microwave towers and other environmental concerns), etc. The variables are many and this will take a good while to sort out.

Look also at your bag or cart where the SQN is. Check for metal objects around the receivers, magnets, crossing audio and power cables, and be sure to check the power situation on your SQN. Are the angles/orientations of your antennae the same between your bag/cart and the wireless transmitters?

Finally, see if you can borrow the same wireless units (same model) from someone else to just check the hardware itself, or rent a duplicate set someday to run the same tests you have on the gear you own.

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    If it is interference, 'RF spray' is the term that is used for this occurrence. Google your setup with that term and "jwsound'. You might get someone experiencing a similar problem. Usually, RF spray is a problem when your mixer and wireless receivers aren't shielded adequately from one another. What bag are you using? Most location recordist have this problem when they mix different wireless sets with one another i.e. lectros with zaxcom. – user6513 Apr 24 '14 at 15:55
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I would first start by isolating devices to the minimum subset where you can reproduce the problem. For example, if the mixer isn't plugged in to the camera, is it still a problem? If levels are peaking, is gain set properly, does adjusting gain impact the problem more or less than expected? Does XLR vs 1/4" make a difference on the noise. Are the cameras, wireless receivers and mixer all using a common power supply? Does changing the power source or moving one or more devices off the same power supply make a difference?

There are simply too many variable for what you have currently stated and a lot of troubleshooting steps yet to be done. If you can post a sample of the audio, that might help in being able to provide further feedback as well, but right now, there isn't much to go on other than suggesting additional diagnostic steps you can try.

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