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Old June 28th, 2012, 11:29 AM   #1
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Weird interference type noises from wireless mic?

Hey guys, I tested out a wireless mic yesterday for the wedding I'm doing tomorrow (it's the only one I could get my hands on unfortunately) and it seemed to work great, except for a few times in the file it like statics up and cuts and pops... any idea what that would be? I'm no audio expert, I just threw the mic on him and threw the receiver on my camera then ran it into my h4n.. I could try and hide the receiver closer if you think that'd help... anyway, let me know, thanks!

It starts around 0:20, and gets really bad around 4:00, and a good example of the cutting is around 8:00
Here's the test file.
Wireless Mic test by Evan Bourcier on SoundCloud - Create, record and share your sounds for free
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Old June 28th, 2012, 12:13 PM   #2
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Re: Weird interference type noises from wireless mic?

That sounds to me like weak signal dropouts. Make sure that the transmit antenna isn't touching any skin. Use fresh batteries. Keep the receiver as close as is practical to the transmitter. Use headphones to monitor the audio. But you probably know this stuff already.
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Old June 28th, 2012, 01:22 PM   #3
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Re: Weird interference type noises from wireless mic?

What type of wireless kit is it? Have you scanned frequencies? Also keep the tx/rx antennas on the same plane, i.e. vertical or horizontal. Turn off your cell phone, increase the squelch setting, don't use rechargeable batteries, try moving the receiver around a bit on or off of the camera - my monitor cable messes up the reception of my Sennheiser kit.

Go down the list and by process of elimination figure out whats causing the interference. Otherwise, it could just be the system itself.
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Old June 28th, 2012, 01:40 PM   #4
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Re: Weird interference type noises from wireless mic?

There could be one other reason for the interference and that's the good ol cellphones hunting for the network. DIT DIT DIT! I hate them during critical audio work but in a large group like a seminar or a wedding there is little you can do. YOu aren't going to get everyone to shut them off. Blackberry's are the worst. They mak a very loud noise when they hunt the network. Not saying that's what it is. It's a very distinct noise. DIT DIT DIT with a z on the end. No other way to explain it. Once you hear it, you'll never forget it. Just something to keep in mind for later.
When I do talking heads I insist they either turn their phone off or give it to someone who is off set. I turn mine off as well.
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Old June 28th, 2012, 04:08 PM   #5
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Re: Weird interference type noises from wireless mic?

I did not listen to the whole thing, but I heard hiss creeping in from low signal strength, and then outright dropouts as the receiver went into squelch (mute) when the signal dropped so low that it couldn't even recover marginal audio. I did NOT hear any cell phone interference, or any other kind of RF interference, for that matter.

I would NEVER do this kind of gig without a fresh battery in the transmitter and receiver. And I don't trust rechargeable batteries, and I only buy batteries at places that have high turnover (so you are assured of a fresh batch). And have 100% backup for batteries, also.

As others have said, keeping the antennas out where they can operate is a prime requirement. And minimizing the distance between the transmitter and receiver. Even if you have to put the receiver up near the transmitter and run a long cable back to your camera (or mixer, etc.) Or using larger (and/or directional) receiver antennas. These are some of the ways to increase the signal available to the receiver and minimize those kinds of weak signal artifacts.
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Old June 29th, 2012, 08:40 AM   #6
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Re: Weird interference type noises from wireless mic?

I agree totally with Richard.

What frequency range does this wireless operate in?

Sounds like there was a signal fighting your transmitter to get to your receiver.

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Old June 29th, 2012, 03:16 PM   #7
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Re: Weird interference type noises from wireless mic?

Signal strength issues - very typical sound. Low signal caused by distance, attenuation from obstacles in the path (usually people), and lastly dead spots caused by reflections that produce areas where if the transmitter strays into them, signal is suddenly lost - theatre folk often call them black holes. Moving the receivers or if used, the remote aerials can usually sort this one. In fact it's this kind of problem that diversity deceivers were designed to solve. Few camera systems have diversity, and those that do are the more expensive ones. I too heard nothing to suggest interference or any form of co-channel noise - that kind of noise has a very particular sound. This clip just make the 'phut' noise as the squelch closes.
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Old July 3rd, 2012, 11:07 AM   #8
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Re: Weird interference type noises from wireless mic?

Quote:
Originally Posted by Richard Crowley View Post
I don't trust rechargeable batteries, and I only buy batteries at places that have high turnover (so you are assured of a fresh batch).
Richard I use to buy fresh batteries for every event & only used them once regardless if they still had 80% of juice left until I discovered Sanyo's Eneloop batteries. Do yourself a favour and try the XX Eneloop's they don't lose charge. I've been using them for over a year with zero problems, can't believe how many batteries & how much money I wasted before I found them.

As for the audio problem, that's definitely signal dropouts not interference as mentioned by the others here. Are you using a UHF transmitter? If this is a new problem open up your wireless unit and check that the wire connected to the antenna hasn't come lose, I've had that happen before to one of my units.
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Old July 3rd, 2012, 03:38 PM   #9
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Re: Weird interference type noises from wireless mic?

When in doubt and for testing, use fresh Alkaline or Lithium batteries.
That being said, I've gotten very good performance and reliability from Rayovac Hybrids. Like the Eneloops, the "Hybrids" do not 'self-discharge' like standard rechargeables, maintaining more than 85% of a full charge over a year. (so they say) Unfortunately they are still only rated a 1.2V, so a alkaline battery meter isn't accurate, so due diligence must be exercised, keeping track of run-time, keeping pairs or sets together, re-charging and such.
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Old July 6th, 2012, 03:13 PM   #10
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Re: Weird interference type noises from wireless mic?

+1 for eneloops. With voltage-regulated wireless systems (e.g. Senn g3) especially, there's no reason to use alkalines anymore except if you just can't be bothered to recharge.
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Old July 8th, 2012, 07:37 AM   #11
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Re: Weird interference type noises from wireless mic?

I can find AA batteries but what about PP9's ?
Should be PP3 the little 9v batteries

Last edited by Donald McPherson; July 8th, 2012 at 08:10 AM. Reason: PP9 should be PP3
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Old July 8th, 2012, 08:03 AM   #12
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Re: Weird interference type noises from wireless mic?

PP9 appears to be a very odd battery. I don't believe I've ever seen one.
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