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gabelinkiewicz

Arri UDM - 1 ultra sonic pain in the

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Yesterday I boom opped a commercial that had the strangest interference occurring over with wireless systems. It was a faint, fast, rhythmic rumble. It took the mixer and I all day to figure out the problem. Luckily the boom was clean, but it damn near drove us nuts trying to figure it out. We changed frequencies about a dozen times, which seemed to help in the short term, but right when we went for a take the sound persisted. We swapped it cables, and several other 'fixes'. Heck we even wondered if it was the boom acting as some kind of antenna because it would coincide when I raised my boom up for a take.

 

Turns out it was the camera's range finding system! They were using an ultrasonic range finder that was overloading the mic capsules of the Lavs. We would only hear it during the take because that's when the damn thing was pointed directly at the actors. Upon further testing we learned it was a purely acoustic problem with the small diaphragm mic being bombarded by the ultrasonic waves. The camera department said they had never heard of that issue before.

 

Has anyone else experienced this problem? I searched all around the web and all I could find was one forum on gearslutz. Here's the link for the curious.

 

https://www.gearslutz.com/board/remote-possibilities-acoustic-music-location-recording/911813-sound-killed-arri-udm-1-ultrasonic-measurement.html

 

Figured I'd posted about it so more info on the topic could be known.

 

Was shooting on the Arri mini. Attached to camera was the Arri UDM - 1 sonic range finder. We were using countrymen b3's and Sony UWP- D11 wireless.

 

 

 

 

 

Sent from my iPhone using Tapatalk

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can't add any personal experience, but I'm wondering:

Did you test the B3's on a direct cable (with an Eumel) or another wireless set?

Because it could be a filter/compander issue of the Sony's, which would explain why there aren't more reports of this (not many projects will use a Arri UDM-1 with a Sony UWP-D11 on the same shoot due to being in different price ranges, i.e. high end camera accessary vs low end wireless system)

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Good point. Though I'm curious why the guy on the gearslutz forum had the same problem with Audio Ltd wireless and b6's, VT 506, and VT 403 mics.


Sent from my iPhone using Tapatalk

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yeah, true...

didn't read the gs thread but glimpsing through it it looks like their test was pretty extensive, so maybe it's indeed the mic capsule size.

as a side note, just went to the array site to check if I could find the frequency of the ultrasonic pulses, and funny enough the manual is only available in english, spanisch and russian (or at least I find that funny : )

didn't find out about the frequency though

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Were your lav mics hidden on the talent, like under layers of clothing?  Did they have any sort of windscreen or "overcover" on them?  I ask because it seems like ultra high freqs would be easily blocked by almost anything....?

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Had that happen to me on different shots. If I remember correctly it was with sk5212 and Audio 2040. Lavs were DPA and Sanken but heard the noise also wireless boom with mkh8050, mkh50, mkh60 and I think CMIT too.

 

Turning the power down on the range finder helps a little but turning it off was the only real fix. Happend to me mostly on close ups and something like that. 

 

Used this year mostly wisycom and didn't had the Problem, so maybe it has something to do with the compander?

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