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A moment of weirdness - multiple lavs

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Tom Galli
A moment of weirdness - multiple lavs
on Jan 7, 2020 at 12:56:22 am

Aloha all, and happy new year!

I'm going to describe this in detail, but the crux is, a setup that had been working flawlessly for 2 days suddenly experienced a bizarre, and production-halting, hiccup. After a few moments of frantic troubleshooting, I bypassed the issue, which self-corrected before I could return to look into it minutes later.

The project is a small indie film. The recorder is a Tascam DR-680. I was running 6 wireless mics. CH 1-3 were Sennheiser lavs. CH 4&5 were Sony URX/UTX P03 lavs. CH 6 was an older Sony P02 with the plug-in transmitter attached to a shotgun on a boom.

It was a 2-day shoot. The actress on CH 4 had lines throughout both days, so I kept her on the same mic and same channel for both shoots. Saturday, there were no problems. Late in the day Sunday, in between two takes of the same shot, suddenly I started getting a very loud, terribly over-modulated noise from CH 4. The director was calling for places; I yelled "hold for sound!"

As I yelled, the noise momentarily cut out. Talking to myself, I said "What the..." It cut out momentarily again. Every time I spoke, the channel would cut out. I started to realize that what I was hearing was a ridiculously overblown audio feed of myself! I could hear myself moving, and when I took the headphones off of my head, I could hear feedback beginning to ring.

I unplugged the receiver from the recorder, and moved it over to CH 5, which wasn't in use for that particular scene. The noise followed it, moving to CH 5, so I was reasonably confident it was in that mic/receiver as opposed to the recorder. Not a problem, I had 2 mics available, as neither CH 2 nor CH 5 was in use at the moment. I waved the talent over, swapped her mic for #2, and we resumed shooting.

When we finished the scene, I went back to troubleshoot, but the issue was gone. Which was good; I needed all 6 mics for some subsequent scenes, and everything functioned flawlessly.

My first thought was that, somehow, the recorder had hiccuped, and the built-in mic was overwriting CH 4. One hole in that theory is that there is no built-in mic on the DR-680. Big hole. Another hole is that the sound moved when I swapped plugs around.

During the time of the incident, the 2 unused lav mics were sitting on the table with me. Mic 5 was the same make/model as Mic 4, so maybe some freak environmental change caused the signal from mic 5 to bleed into mic 4? That would account for me hearing myself, but doesn't explain why it happened only for those few minutes during 2 solid days of operation.

The only oddity I found, in looking things over afterwards, is that phantom power was turned on to CH 5&6. I know I had turned phantom off for all channels when I set up at the start of the day, but maybe I hit that switch during handling, or maybe someone had been looking at my toys during a break. Anyway, I turned it off, but the situation had self-resolved before I made that discovery, so I don't think it was the culprit.

Anyone have thoughts on what would cause a hiccup such as I described?

Tom G

The difference between theory and reality is that, in theory, there is no difference between theory and reality.

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