Digital Chatter on wired connections?

ACTSTech

Well-Known Member
So this is weird...

We had a small cabaret-style performance which we recorded so the vocal coaches could work with the performers after the fact (shocking that the vocalists think everything is just wonderful about their performances isn't it? I digress...) The show sounded fine, but when I went to normalize the tracks, I had digital chatter on some of the microphones, but none of them were wireless. It wasn't constant, it was occasional and intermittent. Sometimes it was loud, sometimes soft. It sounded like cell phone interference, but there wasn't any wireless for the cells to cause problems.

The board is a Behringer X32, not connected to the internet, recording over USB connection. Never had this problem in the past. Anyone else ever hear chatter like this? If anyone wants a sample, I'll provide snippets.
 
So this is weird...

We had a small cabaret-style performance which we recorded so the vocal coaches could work with the performers after the fact (shocking that the vocalists think everything is just wonderful about their performances isn't it? I digress...) The show sounded fine, but when I went to normalize the tracks, I had digital chatter on some of the microphones, but none of them were wireless. It wasn't constant, it was occasional and intermittent. Sometimes it was loud, sometimes soft. It sounded like cell phone interference, but there wasn't any wireless for the cells to cause problems.

The board is a Behringer X32, not connected to the internet, recording over USB connection. Never had this problem in the past. Anyone else ever hear chatter like this? If anyone wants a sample, I'll provide snippets.
Give us a sample, please. "Digital chatter" could describe too many things.
 
Keep in mind that cell phones can interfere with any microphone, not just wireless mics. Corded, condenser mics seem to be fairly susceptible due to their internal electronics. Newer condenser designs are probably better than ones that pre-date wide use of cell phones. Dynamic mics are not susceptible unless the interference affects the mic preamp. Most mic preamps seem to be immune, but I'm sure a few aren't.

Wireless lav and headset mics are most vulnerable because the mic cable is an antenna for the RF. Pockets can easily put a phone too close to the mic, the cable, or the beltpack. The closer the phone is, the more chance there is for audio interference. Plastic belt-packs could be worse than metal cased ones.

I have not experienced interference in wireless, handheld mics. They might have to be designed better to keep their own RF out of the audio circuitry.

The phone carrier type makes a significant difference. AT&T and T Mobile use GSM for 2G and 3G. GSM is nasty for audio interference, but it is being phased out. CDMA, used by Verizon and Sprint, never seemed to be a problem. I have not run into problems lately, so 4G doesn't seem to be a threat. Too soon to tell about 5G.

I remember mixing a live broadcast with jazz trumpeter Clark Terry. Right in the middle of the show, bzzzt, bzzzt, bzzzt. It turned out that his phone was in his shirt pocket. I had a condenser mic, either an AKG C535 or a Neumann KMS105, in front of him for voice. The trumpet mic, being farther away, was clean. After that incident, I made it a point to ask for phones to be turned off, not just silenced, during broadcasts.
 
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I've had issues with laptops connected by usb to some consoles that bleed lots of digital noise from the laptops power supplies, especially ungrounded supplies. Unplug the laptops psu and all is good, plug it in and noise. I ended up creating a usb cable with the ground floating. A hack, but it worked.

As for cell phones.....when I had a tape deck in my car, you couldn't keep a cell phone within 4 feet of it or you got the cell phone song. Granted it was a little more gain then a mic. Back when I had a 2g phone, if it rang....and happened to be sitting on top of a simplex fire alarm panel by the side of a stage.....it would set the alarm off. It wasn't very funny at the time....but it sure is now!
 
My confusion in the whole deal is that the chatter isn't confined to one channel, it bounces and it's at different frequencies every time. The computer is a desktop (I know, that doesn't mean anything) but they're in the same power conditioner, so it shouldn't be dirty power causing it. And the setup is basically the same that has been used in the past, performers are the same, no wireless in use, no DI boxes, no changes to the system, just strange that over an hour and a half the ghost bounces all over.
 
My confusion in the whole deal is that the chatter isn't confined to one channel, it bounces and it's at different frequencies every time. The computer is a desktop (I know, that doesn't mean anything) but they're in the same power conditioner, so it shouldn't be dirty power causing it. And the setup is basically the same that has been used in the past, performers are the same, no wireless in use, no DI boxes, no changes to the system, just strange that over an hour and a half the ghost bounces all over.
Another possibility is a failing power supply (any external device connected to the computer via USB) that is dumping unfiltered harmonics back onto the AC service neutral.
 
I doubt there's anything to the phone cradle other than a gimmick that looks rather quaint now. That was included back when the iPhones 4S was hot stuff.

Laptop power supplies have been known to produce ground noise currents. Most switching power supply designers should be shot.
 

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