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Gear / Technical Help => Ask The Tapers => Topic started by: fandelive on April 17, 2015, 09:00:53 AM
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Attending a show tonight and I'm affraid there will be alot of cellphone addicts in the audience. Got interference noise in a recording in the past.
I was thinking about wrapping my preamp into silver/aluminum foil. Do you think it would help ?
Thanks,
-fandelive
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I use a STC-9200 which is similar to the STC-9100. I've never experienced cell phone interference that I could personally detect. That doesn't mean it never happened but I've never noticed it. The STC-9200 usually has CA-14s going to the input and a DR-2d on the other end.
This is a good idea but I'm not really sure if it would work or not, seems like it would have been mentioned in one of the many threads about phone interference. Could it possibly make things worse somehow by adding more metal near the amp?
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I have run into radio interference issues before and the problem, as best I can tell, was a long cable run where one of the connections was rubbing or we had a shielding problem in the cable.
Behringer makes a handy battery powered cable tester, BTW.
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(http://www.nwsportsbeat.com/wp-content/uploads/2012/03/Tinfoil-head.jpg)
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I know next to nothing about the technical side of how interference effects gear, but I do know it can be picked up by the cables themselves. So fool-proofing the preamp may not be enough (not that I think the tinfoil is a good idea though). Longer cable runs and unbalanced cables both increase the susceptibility to interference.
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What about ferrite beads on the cables?
That's more of a question than a solution because I don't know if they would also affect the actual recording itself.
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My experience is that if your overall system is susceptible to this kind of interference there is little you can do, except change the system. I tried foil and ferrites but no can do. I went fully balanced and haven't had a problem since.
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I still endorse using Neutriks EMC series connectors with low capacitance double shielded starquad mic cables as a defense for this. Cell phones are everywhere these days and good luck trying to get everyone around you to turn off their GSM phones for a performance. High quality input transformers are also recommended, especially if you ever use long cable runs. It is much better to prevent interference than to try and remove it once it has been recorded.
http://www.neutrik.com/en/xlr/xlr-cable-connectors/emc-series/
(http://www.neutrik.com/website/uploads/images/05/660x/emc-explanation.jpg?v=1)
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That's not a practical solution with a PIP input preamp.
:facepalm: ;D Click the photo below, these guys were rockin' a PIP preamp and mic'd up with spaced omni hats.
(http://files.qrz.com/q/nz1q/RediscoverRadio_bmp.jpg) (http://upload.wikimedia.org/wikipedia/commons/a/a7/Buzzing_Speakers.ogg)
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Love the spaced omni hats! Thanks for the good info and link to the Neutrik connectors.
I
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Using tin foil is a well known diagnostic technique, but it is not the engineering solution. However, there is nothing wrong with trying it. I've certainly known it to work on an M10 + Battery box combination.
I have a CA9100 and it is not immune to interference, especially from stage lighting. That isn't a criticism. Managing EMC is a black art and you are at the mercy of the other device(s). Remember the definition of electricity. It's magic and it hurts if you touch it.
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Love the spaced omni hats! Thanks for the good info and link to the Neutrik connectors.
I
It was the first recording for the Nixon brothers. Their recording notes stated they were stealthing from the back kiddie corner table. It was at Devo's 2010 "Something for Everybody - Tour" They went to the show with their Dad and Uncle Richard III who set them up with the rig. Unfortunately they didn't plan on all the fans at the show tweeting out pictures with their cell phones of the two boys because they looked so cute in their Devo hats. Once they listened to their recording at home they were surprised you couldn't even hear the "Fresh" new tunes performed by the band, all that came out was GSM noise. ;)