Hardwired lav picking up local radio broadcast?

[acdave]

Today, on a job fraught with strange problems, here's a new one for me.

In a high-rise office building in downtown San Francisco location, a hardwired COS-11 powered by an Ambient Eumel from my SD 552 began picking up music from some local radio broadcast. Lite rock, I believe.

After letting other members of the crew listen to confirm I wasn't crazy, I quickly swapped out the COS-11 with another COS-11 and the problem disappeared.

Can anyone tell me what may have caused this and how to remedy it in the future?

Thanks!

Dave Wendlinger

San Francisco, CA

[BVS]

Check the earthing on that first COS-11 Dave..it may have a poor grounding in which case it will act as an aerial for local RF.

BVS

[Glen Trew]

An AM station, no doubt.

The newer COS-11D has increased rejection of RF (the "D" is for digital, as in the AM transmission of digital wireless microphones, such as those made by Zaxcom). It could be that one of your mic is a "D", and the other is a bit older.

Glen Trew

[jacefivesound]

When we built Hell's Kitchen season 3 we were literally underneath two huge transmitting towers for ESPN in Culver City. That radio Station would pop up randomly across the DM 2000s, although the wonderful folks from Bexel/ASG built some "radio blasters" to get rid of almost all of the problem. 30+ channels of wireless under 2 super high powered transmitters, what could go wrong?

[Mirror]

I'm with BVS, sounds like a shielding problem.

[studiomprd]

" Lite rock, I believe. "

call sign??

" transmitting towers for ESPN "

ESPN is a network, and they would have satellite dishes. ESPN TV is on cable, not broadcast; ESPN radio is a network, so the towers belong to their local affiliates.

[acdave]

Thanks all for the feedback, as it were.

The COS-11s were of the same vintage, but I agree it sounds like a shielding problem. I'll have it checked out.

I didn't have time to wait around for a call sign, and I hope I never hear that particular station in that way again.

I do film in that specific office space every few months so I'll keep my ears open in the future. I'm not sure what other tenants reside in that building.

Dave Wendlinger

[johnpaul215]

I agree that you should first check the ground connections, it's the most likely cause. It's also possible the shielding is somehow goofed up in the mic cable (somewhere that you can't see it). I would tag that one mic and see if it happens again, and then you can confirm it is the mic and not something else in the chain.

[Chris McCallum]

I had similar problems some years ago and it was a combination of the cable length acting as an antanae for the wavelength of an AM station. Changing the length of the cable fixed the problem