How do I get rid of cell phone interference in my computer speakers?

December 5, 2004 6:27 PM

I know that the clicking coming from my computer speakers is probably cell phone interference. The question is, how do I get rid of it? [there is more, you know where].

About a month ago, I got new computer speakers. While they are infinitely more awesome than my old speakers, they seem to pick up more electromagnetic interference. Not only do my new speakers click when a cell phone in the room goes off, they pick up interference from cell phone devices in near-by rooms, which is really driving me crazy. Turning off the speakers doesn't solve the problem - I have to physically unplug them from the wall, which is becoming a pain. How can I partially shield my speakers so they don't pick up so much interference?

posted by muddgirl to Technology (12 answers total)

Wow. That is really sensitive. I've seen exactly what you're describing, but only when the phone is very close, like under 24". Here's a related AskMe question I popped long ago.
posted by scarabic at 6:45 PM on December 5, 2004

Response by poster: Ah, thanks for the link, scarabic. I thought a similar question had been asked, but i couldn't find it with a google search.

As for the sensitivity - I was really surprised, too. It took me a while to realize that the interference wasn't from my cell phone, but from my neighbors.
posted by muddgirl at 7:53 PM on December 5, 2004

They shouldn't do that, and they may even be broken. I recommend taking them back.
posted by cillit bang at 8:07 PM on December 5, 2004

It could be a grounding issue. Make sure the speakers are properly grounded.
posted by Doohickie at 8:25 PM on December 5, 2004

Best answer: Wow. Questions: are you sure it is your neighbors' cell phone or is it a cordless phone? Not that it matters since it's still your problem, just curious. The speakers must be amplified since you mentioned pulling them out of the wall. Are they grounded (i.e. does the cord to the wall have a third pin)? Are they plugged (for some reason) into a different outlet than the computer? Without going all pepsiblue, could you maybe post the speaker model in question?

Ideas: Solving electrical pickup and ground loops is a black art and lifelong pursuit. If you can, replace the cable connecting the computer and speaker (shorter if you can). If you can't, add a needless male-to-female extension cable which will help spoil any rf resonances in the cable. Another way to spoil rf resonance is to wrap a few turns of the cable around a ferrite bead (an iron chain link will do).

Just For Fun(tm), you could fashion a pair of Faraday cages out of any old wire mesh material you can find around and report the results (make sure to ground the cages)? This won't cure the problem if the coupling is in the wire connecting the computer to the speakers or in the soundcard but it's a silver bullet if the speakers have poor shielding (which sounds plausible if the speakers are small, attractive, and not at all tank-like).

Lastly, try reading here and more generally here for other useful ideas.
posted by fatllama at 9:41 PM on December 5, 2004

Response by poster: Well, they're Altec Lansing V-3121. My neighbors are right on the other side of the wall, probably less than 5'. Moving the computer is an option, of course, but not an attractive one. I've actually thought about building a Faraday cage, just for fun of course, but I don't think my roommate would like it. Thanks for all the links and suggestions.

Strangely, the power cable isn't grounded...I should probably get that swapped out.
posted by muddgirl at 10:45 PM on December 5, 2004

Best answer: Uh oh. Looks like a 3-piece lemon.

I've actually thought about building a Faraday cage, just for fun of course

Yes, *ahem*, just for fun. Of course.
/threeCheersForMuddgirl
posted by fatllama at 11:13 PM on December 5, 2004

Best answer: If it is a cordless at 2.4GHz and you do build a cage the holes in the cage shouldn't be any larger than those in the door of your microwave.

Your probably picking up the interference from the cords going into the speakers. Long lengths of wire make pretty good antennas. Try rerouting the audio cables and use an extension cord to plug into a different curcuit.
posted by Mitheral at 8:15 AM on December 6, 2004

From those Amazon reviews it sounds like the unit is just really prone to noise and interference. I hate to say, but your only option aside from making Faraday cages is to get some new speakers. Let me shill for a sec: I've got a set of Logitech Z-3s and they're cheap (heck, they're cheap even without the $10 rebate that Amazon has now), stylish, and sound decent. They only pick up noise from my cell phone if it's right next to the volume control or speakers.
posted by zsazsa at 10:54 AM on December 6, 2004

My crappy Nokia cellphone not only interferes with my computer speakers, but (when I'm nearby) the computer speakers of my co-workers and our baby monitor. Now that I read it, Orb's comment in the other Ask Mefi thread partially blames Nokia for the poor shielding.

So maybe this doesn't apply.
posted by waxpancake at 12:01 PM on December 6, 2004

Nokias may be worse because they're actually better - i.e. they emit a stronger radio signal.
posted by zsazsa at 12:32 PM on December 6, 2004

Response by poster: Uh oh. Looks like a 3-piece lemon.

Well, I got them cheap-as-in-free, and I don't tend to look gift horses in the mouth.

Thanks again for all the advice. I haven't heard any clicks for the last few days...
posted by muddgirl at 12:56 PM on December 7, 2004