Topic: Cell phone interference: how can I shield against it / what's wrong with my rig?

[whatboutbob]

What a nightmare..  It would be good to learn which other mics/rigs are prone to this type of interference.. I'm wondering about 406x, etc...  I am guessing that SD mics with grounded metal bodies and balanced signals will do better (though the SP-C4 mics are not balanced).

Before you get too worried, just keep in mind that this seems to be fairly region-specific...or at least network-type specific (GSM) which seems like its not prevalent in the US.

[whatboutbob]

Ahh...didn't realise that.

[SparkE!]

Before you get too worried, just keep in mind that this seems to be fairly region-specific...or at least network-type specific (GSM) which seems like its not prevalent in the US.

There are definitely GSM cellphones in the US.  Many Blackberry devices are GSM as well as CDMA. Don't get too comfortable...

Ahh...didn't realise that.

Yes, but most of ours in the US are in the 1900 MHz band.  I think that Australia's GSM phones are mostly in the 800 MHz band, aren't they?  They use the same channel access protocols, but they are just in different parts of the rf spectrum.

[whatboutbob]

Yes, but most of ours in the US are in the 1900 MHz band.  I think that Australia's GSM phones are mostly in the 800 MHz band, aren't they?  They use the same channel access protocols, but they are just in different parts of the rf spectrum.

I'm not sure which band they're mostly in, but the network is dual band: 900 and 1800MHz

[SparkE!]

I'm not sure which band they're mostly in, but the network is dual band: 900 and 1800MHz

Oops, yes that's right.  I was thinking 900 and typed 800, but I didn't realize that GSM had gone dual band there.  I guess that makes sense with the use of smaller phones.  Europe is also 900/1800.

[willndmb]

i got cell phone probs for the 1st time at a show a week or so ago, the guy next to me was letting his friend listen in
not sure what picked up the signal
393 > UA-5 > JB3
i never had a prob in the past with people around using their phone, hope i don't again
lucky it wasn't to bad and only for a few seconds

[Unitmonster]

I never once had a problem with my UA-5>JB3 setup, including 2 recent radiohead shows that were cell-phone central.

[hyperplane]

I know I'm chiming in late and all. But for whatever this is worth (or not), here goes...

Recently while browsing around for some cables and such, to make some custom items, I saw some "RF protected" cables listed. Is it possible to simply re-wire the Audio Technica mics you have? (Or see if Chris Church can, or would be willing to, do this for you) ?

I know it's probably a dumb idea, and I don't know if this would even be a potential solution, but a few feet of cable isn't *that* expensive (surely cheaper than buying new mics) so I thought I'd throw the idea out there.

[whatboutbob]

thanks for piping in.

i'm pretty sure its the mic caps that are the problem tho (going by the jump in volume of the interference according to the proximity of the phone to the caps), so while RF-protected cables may help, but it won't eliminate the issue.

I haven't managed to get to the post office during the day yet, but will do so soon cos i'm keen to see if Chris can work some magic.

[jbraveman]

My DPA 4022 caps have the same problem in combination with nextel/blackberry service.

http://taperssection.com/index.php?topic=67991.0

[kuuan]

after reading through this thread I became curious if the Sound Professionals would use the new AT's UniGuard technology for their CMC mic line:
My questions may betray a beginner, but nevertheless, here what I had asked to the SP technical assisteance and the answers ( inbold ) I just received:

Hi, good morning,
 
there have been numerous reports of interference to recordings due to GSM cell phones.
 
In a statement of an official of Audio Technic I ran across it says:
'The GSM interference issue has been a huge problem for the audio industry.  We addressed (and resolved) this in our revamp of the UniPoint line with the UniGuard technology. You may need to upgrade to the new UniPoint line to resolve your issues.'
( of interference )
 
If I am not mistaken there is e.g. a new replacement of the AT853 which is called U853 incorporating the UniGuard technology.
I am very much interested in yout SP-CMC4 mics ( I prefer the small miniplug to the heavy XLR )
 
My question therefore is:
Will SP integrate the UniGuard technology in the SP-CMC line, resp. will there be a SP-CMC4 incorporating the UniGuard technology?
 
Yes, once they are available. AT has not yet made the new version available to the OEM market (us).

Or would that not make sense since the CMCs use unbalanced lines?
 
Unknown.....but my guess is that there would be little benefit since they are usually wired unbalanced. Of course, we do offer options to keep them balanced as well.
As for reports of interference, there are well over 1000 sets of these in the field.....I have personally heard of 2 occurrences of interference so far. ....mainly because the cable length on these is only 4 feet and the cable length on the regular model which is used for hanging over choirs is 25 feet or longer.
 
thank you for your attention,
 
If you have any additional questions, please let me know.
Best Regards,
.....

[jibooer]

just to put my .02 in, I would like to address the fact that some people are getting ticking on their CF card recordings from bleeding during the transfer of data during the recording...it is very similar to the sounds made by RF intereference. This problem has been brought to the attention of D.Oade in regards to some of the earlier models of the PMD-6**...

[kuba]

I can't get any cell interference no matter how hard I try.

AT831 (Audio-Technica 6 feet cables) > DIY battery box (two wire, 9V, plastic box, no shielding at all) > 1 foot cable (taken from Sony earbuds) > H120

Sorry if I'm too late or if it doesn't help anything, I didn't read all 7 pages of this thread.

[beathydrolysis]

I can't get any cell interference no matter how hard I try.

AT831 (Audio-Technica 6 feet cables) > DIY battery box (two wire, 9V, plastic box, no shielding at all) > 1 foot cable (taken from Sony earbuds) > H120

Sorry if I'm too late or if it doesn't help anything, I didn't read all 7 pages of this thread.

Are you using a GSM phone?  I think the intereference problem has been targeted to GSM phones specifically.  Unless you or someone you know has T-Mobile, you probably are not using a GSM phone and thus are extremely unlikely to generate the interference.  Most of the world is on GSM but in the states almost no one is GSM.  It's too bad GSM causes the interference cuz all around its a better type of network than CDMA and the other garbage we use in the US.

[kuba]

Are you using a GSM phone?  I think the intereference problem has been targeted to GSM phones specifically.  Unless you or someone you know has T-Mobile, you probably are not using a GSM phone and thus are extremely unlikely to generate the interference.  Most of the world is on GSM but in the states almost no one is GSM.  It's too bad GSM causes the interference cuz all around its a better type of network than CDMA and the other garbage we use in the US.

Yep, Vodafone GSM, 900/1800 MHz. I didn't do any sophisticated testing, I was just curious whether to switch of my phone during recording to avoid those awful sounds. I turned on my rig, dial my phone number on another phone and simply moved my phone around the hardware.