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Need a way to block cell phone noise

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I record a lot of marching band type competitions. Recently, the judges at the competitions have been using multiple wifi hotspots to communicate their scores etc. This causes a lot of radio noise type interference with my recording set up. Is there anything I can add to my set up to help filter out the interference? Attached is a picture of my set up. They are AT-853 mics into Samson phantom power adaptors into the Tascam DR-100 mkii.

I am not an expert in RF interference, but I've read that the Neutrik EMC connectors do a good job of rejecting RF noise.

In your case, you'd need to try inserting a pair of EMC cables between your Samson PM4 adapter and the recorder.  If this works, great.  But, it's possible that the interference gets converted to an audio signal before the recorder (i.e. inside the Samson adapter or further upstream), and in that case, the EMC cables wouldn't help.  A new set of mics with XLR connectors plus the EMC cables would be the next thing to try.

You need only one EMC connector per cable - the most common configuration is the connector that mates with the recorder (Neutrik NC3MXX-EMC).
If you want to tackle this yourself, be aware that these connectors are more challenging to solder than standard XLR connectors.  Might be worthwhile to have one of the TS guys make you a nice set of cables.

You might also try wrapping the DR100 and the Samson adapters with a single piece of aluminum foil.  Maybe that will do the trick!

These problems can be quite difficult to solve. If the RF source is close to your equipment and you can't increase the distance (or can't increase it sufficiently), it may prove impossible to solve the problem, though you may be able to reduce the effect of the interference.

It all depends on where the interference is being "detected" (converted into audible signal energy); there may be more than one such point in the circuit. Increasing the distance between the source of the interference and your equipment is the first thing to strive for. As a close second, keep the connections among all your items of equipment as clean, short and direct as possible. Try reorienting cables and other pieces because the angle of signal incidence may affect the strength of the received signal. It is basically like trying to improve reception of a distant radio station that you want to listen to, except exactly in reverse; you want to arrange the worst possible receiving setup for the signals you're receiving in this case.

As mentioned, Neutrik EMC connectors on your XLR-3 cables can definitely help; Schoeps' XLR-3 microphone cables use these; I'm amazed that everyone else's do not (and I'm a bit dismayed that Schoeps' XLR-5 to XLR-3 "Y" cables don't use them). Sescom, by the way, sells XLR-3M to XLR-3F barrel adapters with these connectors, unfortunately only one per unit (i.e. there is one unit available with the EMC XLR-3F and a conventional XLR-3M, plus another unit available with the EMC XLR-3M and a conventional XLR-3F; even Sescom's engineers couldn't explain why when I asked them). You might also try tightening any screws that could be any part of the connections among shields on your cables, microphones and recorder.

Ultimately, though, sorry to say, no one can guarantee a solution. Most audio equipment today, particularly in the consumer and "prosumer" ranges but including a lot of professional equipment, simply wasn't designed to handle the kind of interference that modern cell phones and related equipment can generate. Typical designs and production methods are often quite problematic (try doing a Google search on the "pin 1 problem"--even some top brands of studio equipment have had it, and much if not most "prosumer" equipment still does to this day). A new generation of design engineers, with a stronger awareness of electromagnetic interference, may will have to supplant today's generation of production designers before things get much better.

Or perhaps, since this problem doesn't affect most people most of the time, and most people don't shop specifically for equipment that's known to meet high standards of resistance to electomagnetic interference, the broad mass of equipment sold to the general market may never improve its resistance to EMI. Or the market may continue to muddle through as it has all these years, hoping that no one will blame them as from time to time we all, or nearly all, have recordings ruined in this way without there being anything much that we can do about it.

I'm not an rf knowledgeable person either. But ferrite beads might help.

Balanced audio signal paths are more resistant to interference than unbalanced. You could possibly reduce the noise in your setup by placing the phantom adaptors closer to the mics, (shorter length on the mini-xlr cable, which is unbalnced) and using an XLR-XLR cable to extend the length between the adaptors and the recorder. Copper foil is also a good shielding material, but would need to be properly installed to be effective. Using well shielded cable is also necessary.


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