Topic: Cell phone interference

[dlh]

I'm not new to recording, but my experience was "pre-cell phone".
Last night, at a small club, I experienced my first cell phone interference.
Mics were above a table of several texting addicts.
SDC's are connected through 6' breakouts to 50' Canare stereo cable with 6' breakouts at the recorder.
I built the breakouts with cable from Aquarian Audio because of it's small diameter and fairly rugged construction:

http://www.aquarianaudio.com/product.php?productid=24&cat=0&page=1
"It was specified with a 0.175" jacket diameter, but delivered with a nominal 0.160" diameter, so the cable was remade to spec and we ended up with the surplus. Perfect condition! 24-gauge (40 x 40) oxygen-free balanced conductors with low-capacitance foamed polyethylene dielectric, 95% TC braid with 24-gauge drain, and TPE jacket."

So . . . I'd like opinions, experience, from others regarding the "weak link" in the chain.
Can the cell phone gremlins enter the mic itself?
Should I try rebuilding the breakouts with different cable? (suggestions? I just need cable small enough for two to fit in a Neutrik)
Would shortening the breakouts help?
Did the 50' stereo cable contribute to the problem?
(Or am I just doomed?) 

I'm thinking it's mics or breakouts because the audience was full of cell phone addicts. (Don't get me started.)
The only ones affecting my signal were in close proximity to the mic stand.  (I was watching them.)

Thanks for your help.  I may post some clips later, but I'm convinced, from posts here, that it was cell phone noise.

Dave

[rocksuitcase]

I think a clip may help determine the cause. Without it, I can tell you Cell phone interference used to be common with my D-8 in the DAT taping days.
My opinion is that it is the deck which exhibits or gets affected by the interference.
You did not say what recorder you are using, but the electronics in most digital recorders can be succeptible to certain types of interference.

I'm interested to hear what others experiences have been with cell phone interference during recording.

 

[dlh]

Recorder: Fostex FR-2le

[page]

Recorder: Fostex FR-2le

I only had some sort of cell interference with the fr2le once and it was in a sea of other tapers. 

Was any of your connections unbalanced, especially the 50' one?

[Shadow_7]

Mics can pick it up.  Cables can pick it up.  The connectors can pick it up.  Even the recorder itself can pick it up.  It's a tough one to troubleshoot.  Proximity to the interference helps generalize where the link is deficient.  But not really an indication of why / how / how much.  It could be combinations of things.  I have a Korg MR-1000 and Avenson STO-2 and Mogami quad core cables.  Mostly immune to cell phones.  Now if the house system isn't and transmits that over the PA, then sound is generated and recorded by the mics.  My setup isn't immune by any means.  The mics seem sensitive to high voltage.  And the whole kit sensitive to radio towers.  It's the mics lowering them helped.  It's the field recorder, ducking it under aluminum bleachers helped.  It's the headphones, it sounded way worse on location than back at the cave.  It's the cables, because it shouldn't have been anything other than that.  Balanced and shielded, and fancy connectors to prevent weak links is the way to go.  Put the recorder in an aluminum box see if that helps.  Wrap tin foil shiny side out around the connectors, see if that helps.  Use different mics, see if that helps.  There is probably a main cause, but it might not be the only cause.

[dlh]

Recorder: Fostex FR-2le

I only had some sort of cell interference with the fr2le once and it was in a sea of other tapers. 

Was any of your connections unbalanced, especially the 50' one?

All balanced.

[doodee]

I think a clip may help determine the cause. Without it, I can tell you Cell phone interference used to be common with my D-8 in the DAT taping days.
My opinion is that it is the deck which exhibits or gets affected by the interference.
You did not say what recorder you are using, but the electronics in most digital recorders can be succeptible to certain types of interference.

I'm interested to hear what others experiences have been with cell phone interference during recording.

I've had interference issues twice before, both when I was recording with MD. In each case the phone was in pretty close proximity to the recorder, like a foot / foot and a half. I've had no issues since going to the R09HR and DR07 from other patrons' phones around me and have made sure to either power mine down during the show or keep it at least three or four feet away from the recorder.

[notlance]

Here is a link that has some good info on reducing RFI.

http://recforums.prosoundweb.com/index.php/t/1894/0/

I have followed this advice to eliminate most cases of RFI.  It is at least a very good starting point.

[rhinowing]

I've had zero problems using the r-09, and I occasionally have my phone turned on and in the same pocket as the r-09

[dlh]

Here is a link that has some good info on reducing RFI.

http://recforums.prosoundweb.com/index.php/t/1894/0/

I have followed this advice to eliminate most cases of RFI.  It is at least a very good starting point.

Yes it is, and thanks for that link.
I've not been in the habit of connecting the housing ground lug to pin 1, but that's my next step.
Supposedly the only downside is if the connector has physical contact with the ground (wet earth, concrete), but it seems that even that issue is debatable.
I'm now wondering why many commercially produced cables don't make this connection.
So what's the downside of connecting the housing? Thoughts, experience?

Thanks
Dave

[dlh]

http://vids.myspace.com/index.cfm?fuseaction=vids.individual&videoid=9095599

[huskerdu]

These cables may help: http://www.cbicables.com/ShieldSeries.htm

[dlh]

I've finished grounding (pin 1 to housing) cables so I'll test that out at my next visit to the same club.
I tried reproducing the interference with my own cell phone before the cable mod, but my phone is a cheapo so no effect.
I'm doing some post on the audio files now so I should have some clips up before too long.
Thanks for all replies; more to come

Dave

[dlh]

 . . . from the original post.
First one is mono; noise is from left channel only.
Second clip is stereo.
SECOND CLIP IS MUCH LOUDER.

[ccage]

Iv'e been hit twice this year and is my first time to have these problems- maybe newer phones/devices are the cause?

One at Umphree's show in ATL I think was self inflicted from my phone laying next to xlr inputs on my R4 - wav file has intermittent sound like radar echo ping for about 10 seconds
Happened again at Wanee Fest this year for Mule Late Night set - i had my phone off but was near several bags and 1 guy testing a lot. 

Like the looks of those shielded cables - thanks for link!