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Old March 3rd, 2008, 03:51 PM   #1
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What the ?? mic problem

So first off I'll say that I do use a backup recorder on my audio so my wedding video will not be ruined....but this was too close for comfort.

I began picking up major interference at a wedding last week. I tested everything and it was just fine, but about halfway through the ceremony I started to hear some static. It starts really soft and builds until I can't hear anything but that. Then sometimes it will cut out and and i'll have perfect audio again. I have had this happen before with this mic but it was very brief and I figured it was just random interference. Now I'm not so sure. I didn't have this problem the last time I worked at this church so it shouldn't be a location issue either. I was only 25 ft from the couple so it wasn't a matter of distance or being blocked by something.

I have a sennheiser g2 wireless system and am running the XLR adaptor into a beachtek DXA-4. I've never had any problems with this before and I have 2 sony vx2100 setup the same way so I'm pretty sure it's not my setup.

I have talked to different people at sennheiser and I'm starting to get conflicting answers so I figured I would ask all of you wonderfully smart people :-) before I hassle with sending it in. I just wanted to make sure it wasn't something stupid on my part with my audio setup.

Here is a 1 minute grab from the wedding so you can hear what I'm talking about. once it built back up , it stayed for the rest of the ceremony .

http://www.mediainnovations-online.com/mic.wav

I appreciate any help or ideas!!!!!

Matt
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Old March 3rd, 2008, 05:00 PM   #2
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I don't think that it was the mic, sounds like it was a frequency problem with the wireless. Did you check the Sennhesier frequency chart for your areas transmission area, to make sure that you have the best frequency band for your surrounding areas?

Did you do a frequency sweep of the venue before the ceremony, with all wireless transmitters turned on (except yours).

Just because you didn't have a problem with a previous job before at this church doesn't meant that something in the area (not just church) couldn't interfere with your wireless.

But it does sound like a frequency problem.
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Old March 4th, 2008, 10:23 PM   #3
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Oh yeah, I get that a lot when battery power begins to fade. However, with a battery voltage drop there is usually no return of transmission clarity. Things generally go from bad to worse.

Clearly, something is causing interference, but I wouldn't think local TV station broadcast a possible culprit because TV broadcast is constant ... you would always have the problem all of the time. Although I haven't really researched the actual frequencies, I'd take a close look for wi-fi, leaky microwave ovens, etc, within the building. Something that is sometimes on and sometimes off emits a strong enough signal (20 to 50 milliwatts) on the frequencies your wireless system uses to render them inert.

I wonder if there is a downloadable application freely available that can utilize the built-in antennas of laptop computers to identify broadcast frequencies? Once the problem frequency was identified it could be associated with typical consumer or industrial products, thus narrowing your search.
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Old March 4th, 2008, 10:31 PM   #4
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I was using a range of frequencies that, according to sennheiser, is a vacant range in this area so I don't think that would be an issue. Of course it is wireless and some interference is always an issue. I always have new or fairly new batteries in both units so I ruled that out at the very beginning. Again, it wasn't just this location. This wasn't the first time this happened ...it's just never been that bad. thanks for all your input.

There is another business in the area that has the identical setup as I do and they've never had a problem...The only difference is that they have the units with frequency in 700s while mine are in the 500's. Could that be the issue? Could there be more airwaves being used at a lower frequency and therefore more chances for me to get interference??
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Old March 4th, 2008, 10:49 PM   #5
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Is this the only wireless you are using? Want to verify two transmitters are not to close either distance or frequency.

Sometimes my nextel cell phone will cause interference on our wireless so I try to keep it a safe distance away.

I had a similar situation with two of our sennheisers turned out it was a bad mic cable. Very difficult to determine because it was not consistent. Once I changed to a different mic into the transmitter the static was gone.
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Old March 4th, 2008, 10:59 PM   #6
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Yes this is the only system we are using. At this particular ceremony there were no other mics being used (wired or wireless) There was nothing else within 25 ft of myself with the receiver or the groom and the transmitter.
I actually got a new xlr cable sent to me the first time this happened but I ruled that out after it did the same thing with that one.
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Old March 4th, 2008, 11:22 PM   #7
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the xlr cable; is it going to the transmitter in or is it from the receiver out to the beachtek?

is your transmitter the lapel with mic/line input, handheld one piece, or xlr plug?
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Old March 4th, 2008, 11:28 PM   #8
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The transmitter is the ew100 g2 wireless with lapel mic.

the receiver has an xlr cord that runs into the beachtek and the beachtek runs into the 1/8 mic input on the vx2100.

I've used it this way because I have more control over the levels as opposed to using the supplied mini plug that would run the receiver right into the camera via mini.
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Old March 4th, 2008, 11:35 PM   #9
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thats the same setup

the cable that was bad on mine is the actual lapel mic cable, seems it often gets tangled when packed away between use.

if you get the static again try plugging in a different mic with mini plug into the transmitter and see if there is any difference. also check and see what the squelch settings are. hope this helps.
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Old March 5th, 2008, 07:46 AM   #10
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Well I was looking for my long post on my Sennheiser G2100 issue, it's somewhere on this board.

But my experience is, that I ended up going with a frequency range that was not what the Sennheiser chart recommended. It says I need a A range, but with A range I had interference constantly, and was only able to find like one frequency that had 4 free.

Once I switched out, things are much better. When I was having problems with my A range, I called TV stations, radio stations etc and could never really hammer out what the issue was.

The people at Sennheiser were great. I just think there are stations, radio, HD whatever that may not always be listed on a chart.


So I would check with someone who has a different range and see if that makes a difference. It did for me.
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Old March 5th, 2008, 07:50 AM   #11
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I found it http://dvinfo.net/conf/showthread.php?t=99304
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Old March 5th, 2008, 10:14 AM   #12
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I met with a Sennheiser rep in January and he did say that cell phones can interfere with wireless mics. We had a similar instance but the feedback would spike and fall off and then later would get the same thing. No particular pattern. We now make sure that the Groom, Groomsman and Officiant turn their cell phones completely off to avoid this problem.
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Old March 5th, 2008, 10:58 AM   #13
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In thinking this over I am leaning more and more towards he idea of a WI-FI network causing the problem. I ran into this same situation last spring when one of my wireless mics produced a similar hiss. Since the problem occurred in a venue quite familiar to me I was certain something had changed recently. I asked the building's telephone technician if he had made any major changes in the last few months. New WI-FI networks was the answer, although he couldn't tell me the exact frequencies being used.

Will your mics work in another location?
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Old March 5th, 2008, 12:34 PM   #14
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about 80% of the time they work perfectly, but this is the 4th wedding that I've had this problem at so it does work at other locations but at the same time I have had this exact same problem in more than one place. And those locations weren't even in the same general area.
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Old March 5th, 2008, 12:43 PM   #15
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Quote:
Originally Posted by Matt Bishop View Post
about 80% of the time they work perfectly, but this is the 4th wedding that I've had this problem at so it does work at other locations but at the same time I have had this exact same problem in more than one place. And those locations weren't even in the same general area.
And that is the reason I tried a different frequency range. That reason exactly.
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