Weird wireless interference

[RyanDoesSound]

I've been getting this really weird interference at this one location in an apartment complex in Hollywood and was hoping someone could identify the problem. I'm running 1-3 Sennheiser G3s, one with a countryman B3 and others with the stock ME2 mics. All the TXs do it, no matter the amount of kits running or frequencies. And I have tried to recreate the problem at my house without success.

It's not radio hits or drop outs, but this rapid fluctuations in audio levels, almost a gurgling of the levels. The weirdest part is that the second I step outside onto a patio, or even the hallway, it stops. Looking at the TX, when I'm outside on the patio the levels look normal, but right when I walk into the room we're shooting in the level meter spikes and hits the limiter, even if its quieter inside than outside. This is on both B3 mics and ME2s. 

I've tried scanning frequencies, changing banks, groups, sensitivity, everything and no matter what I get issues. My only idea is maybe there is a massive amount of unshielded wiring in the complex and is somehow radiating a ton of electrical energy and overloading the mic cables, making them essentially striking rods.

Here is a tame example. Usually it's jumping about 5-15db 3-5x per second. The crashing sound is a door slamming and blinds shaking. There are no radio hits or drop-outs, just a massive jump in audio levels. Ideas on what this could be?

 

[Philip Perkins]

You are prob right-something electrical in the building--could be a security system, lighting control etc, and even how the two or something else are interacting in that space.  If this is a short-time location you'll prob have to tough it out.  If you are shooting a whole movie in this space, or a lot of it, then it's time to start running through the breaker panel, and checking with the building management about what's going on.  I usually try to find out if the location is a freebie /low-cost thing or a regular fee-type deal.  If it's the latter then I'd get locations and or production on the case right away.

[MartinTheMixer]

Ryan, what do you get if you have a totally as quiet as you can get it background and you walk from a problem area that you have to the non problem area? What does that sound like? Can you record that and let us hear it? In other words go to the non problem area and let the mic sit there for 10 seconds and then give us a countdown of 5, 4, 3 and then go in the problem area. What does that waveform look like?

Sincerely, Martin 

[RyanDoesSound]

5 hours ago, MartinTheMixer said:

Ryan, what do you get if you have a totally as quiet as you can get it background and you walk from a problem area that you have to the non problem area? What does that sound like? Can you record that and let us hear it? In other words go to the non problem area and let the mic sit there for 10 seconds and then give us a countdown of 5, 4, 3 and then go in the problem area. What does that waveform look like?

Sincerely, Martin 

I wasn't able to record a quiet track on location, and I can't recreate the problem at my house, but I did find a better example of when it was bugging out:

 

[Mungo]

Maybe a noise in the room that is not really audible for human ears? Something very low <50Hz or very high >16kHz, perhaps created by an air condition or a device keeping small animals away? That may have strange effects on the HDX compander in your transmitters... 

[Lancashire soundie]

What happens if you turn pilot tone off?

[TommygunZA]

Paranormal? Time to call Ghostbusters? On a more serious note are there any issues with rifle mics or wired Mics, lavs or handheld. I guess its a pain to test all the options. Any sector cell phone masts around. Are you top floor? Any other details...?

[RyanDoesSound]

23 hours ago, Mungo said:

Maybe a noise in the room that is not really audible for human ears? Something very low <50Hz or very high >16kHz, perhaps created by an air condition or a device keeping small animals away? That may have strange effects on the HDX compander in your transmitters... 

You know what, that is a really good theory. I took a look at the spectral frequency display on my boom track and there is a 23 khz constant tone. See attachment.

 

11 hours ago, TommygunZA said:

Paranormal? Time to call Ghostbusters? On a more serious note are there any issues with rifle mics or wired Mics, lavs or handheld. I guess its a pain to test all the options. Any sector cell phone masts around. Are you top floor? Any other details...?

This issue was present in rooms on the top floor (6th) and the 2nd floor, three separate rooms. Two were common areas for the tenants, the third was an apartment. It would only happen inside the rooms. The moment I left the rooms, either into a hallway or outside onto a patio, they would function perfectly. And there were no issues with my boom, but present on 3 separate wireless kits, all with different mics, and different blocks, and from 2 different owners. So the likelyhood of all of them faulting is near zero.

19 hours ago, Lancashire soundie said:

What happens if you turn pilot tone off?

I didn't try that and we are out of that location, so I may never know if that would have solved the issue. 

[Mungo]

19 minutes ago, RyanDoesSound said:

I took a look at the spectral frequency display on my boom track and there is a 23 khz constant tone.

that could have been it. Had that with Sennheiser 5000 and it resulted in a strong gating effect without a clue. Couldn't figure it out though.

Let's hope those tenants won't get mad with this tone around all the time. 

[RyanDoesSound]

3 minutes ago, Mungo said:

that could have been it. Had that with Sennheiser 5000 and it resulted in a strong gating effect without a clue. Couldn't figure it out though.

Let's hope those tenants won't get mad with this tone around all the time. 

Well the normal human ear tops out at 23khz, so it would make sense that it wouldn't bother a normal person. There was a dog in there as well, but it wasn't acting weird or distressed.  But it was a pug and they are strange creatures. 

[Keen]

since you couldn't recreate it at home... was it only in the room with a camera? does the camera have a panatape that might be bad?

[RyanDoesSound]

13 hours ago, tonto said:

since you couldn't recreate it at home... was it only in the room with a camera? does the camera have a panatape that might be bad?

No the issue occurred with or without the camera in the room. 

[Ryan Coomer]

Is there a motion detecting security system in the room? Those use high frequencies and I've heard of them causing problems with G3's.

[Philip Perkins]

3 hours ago, Ryan Coomer said:

Is there a motion detecting security system in the room? Those use high frequencies and I've heard of them causing problems with G3's.

Not just G3s: any mic can pick those up.  I have had to mask those things with duvateen scraps etc.

[RyanDoesSound]

7 hours ago, Ryan Coomer said:

Is there a motion detecting security system in the room? Those use high frequencies and I've heard of them causing problems with G3's.

Not that I saw, and it was happening in the apartments as well as the common areas (sky lounge, conference room, etc.), and it is a very modern building, so my first assumption is that something was installed in every room, most likely a pest control device.