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Sennheiser lav problems

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Joseph Colombatto
Sennheiser lav problems
on Jun 1, 2010 at 2:42:13 pm

I'm shooting with a Panasonic DVX100A and have Sennheiser ew100 G2 lav hooker into the XLR
connector, and am shooting outdoors and it sounds really over modulated. I have the Sensitivity
set @ -00 db and AF OUT set @ -12.
Now, the camera is old (must have a 1000 hours of record time on the heads), so I hooked the
same mic system into a Panasonic AG-HMC40 (AVCHD) with a similar XLR connection and the
sound is fine, which makes me believe it must be the camera heads affecting the modulation.
Is my assumption correct? Am I missing something on the DVX100A? I did notice that phantom
power was on for the INPUT on the DVX, and this particular mic does not require phantom.
Would that affect modulation?

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John Fishback
Re: Sennheiser lav problems
on Jun 1, 2010 at 7:21:12 pm

I'm fairly certain it's not the heads. More likely it is the phantom power. Turn off the phantom power and try again. I'm not familiar with that lav. Are you sure it doesn't use phantom power? Because, if it does, it likely needs a very specific kind of phantom power, one very different from typical phantom power. Wireless lavs use much less phantom power so they don't drain the transmitter's batteries. Another possibility is the two cams have different pin configurations. Check the respective manuals for that.


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Richard Crowley
Re: Sennheiser lav problems
on Jun 1, 2010 at 9:35:20 pm

It is not the heads. The audio is recorded in the same bit-stream with the same heads as the video. If the heads were an issue you would like see video artifacts before you heard audio problems.

It is possible (but doesn't seem very likely, either) that it is the phantom power. Phantom should always be turned OFF unless you know for a fact that you need it.

The most likely cause would seem to be the audio recording levels on the DVX100A. You didn't say anything about how they are set, or what the audio recording levels were indicating. And what did it sound like when recording?

Excellent "differential diagnosis" troubleshooting work to try it in a different camera. Your experiment would seem to show that it isn't overmodulating in the transmitter. ("fault-finding" can be substituted for the word "troubleshooting" for our friends on the east side of the Pond. :-)

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Sam Mallery
Re: Sennheiser lav problems
on Jun 2, 2010 at 3:29:03 pm

Did you adjust the gain on the camera? The DVX100A has two little knobs with arrows in the middle. If they were turned up too high, then it would have sounded like you describe.

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Steve Kownacki
Re: Sennheiser lav problems
on Jun 5, 2010 at 10:05:39 pm

Hi Joseph
Taking a quick look at the online manual, do you have the switch on the front of the camera near the XLR jacks set to mic or line input? If its on mic, you may be overdriving the preamp; move it to line in and hopefully your problem is solved.


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