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[Tell] me how to I prevent insane RF interference in computer speakers?

JerikTelorianJerikTelorian Registered User regular
Last night, I set up my computer in my new house, and all was well. Everything worked fine. Today I get home, boot up the computer and BAM am hit with the nearly crystal clear sound of a radio station. The interference was from an AM station, was louder than the music from my computer, and was extremely annoying.

Some characteristics of the problem:
  • The speakers are amplified
  • Interference did not vary much as I changed the speaker volume
  • Interference was very clearly audible with the computer off, and unplugged
  • Interference was loudest when the speaker cable was plugged into the computer
  • Interference was limited when plugged into my unplugged laptop
  • There seemed to be very little interference if I used unamplified speakers (my headphones)
  • If I shorted the phono plug just right, it would get really loud interference
  • The radio tower is really close to my house; like maybe 4-5 city blocks
  • Wrapping cables in tin foil / attaching ferrite rings to the speaker cables seemed to do nothing at all (or make it worse!)
  • Another crappy speaker set that I have seemed to not have this problem
  • Everything is plugged into an APC battery backup, and that into a grounded outlet. The speakers do not have a grounding line, the PC, of course, does.

I'm in this house for at least two years, so I need a solution. I'm going to go batshit nuts if my system gets horrible interference for the rest of my time here, as I use it often. Is there something I can do to these speakers to fix the problem? Is there something I can do to the PC to ground the audio jacks better?

The radio tower seems to be off at the moment, as the speakers are working fine. Tomorrow, no doubt, it will be on again. When that happens I'll plug my speakers into the backup and run it off battery only; I will see if the problem persists. Any advice would be appreciated before I get all stabby about this.

Also, when I say "interference" I don't mean a slight hiss. I mean that I can clearly hear the radio from another room in the house. It's loud; it plays at the volume I would set the speakers to if I wanted to listen to music.

JerikTelorian on
SteamID -- JerikTelorian
XBL: LiquidSnake2061
Spoiler:

Posts

  • ASimPersonASimPerson And they will tremble again at the sound of our silence.Registered User regular
    edited May 2010
    This was the first hit on Google: http://www.stevelarkins.freeuk.com/computer_interference.htm
    Here's the Wiki article about them: http://en.wikipedia.org/wiki/Ferrite_bead

    I imagine you would be able to buy these on the cheap at your favorite electronics retailer that actually carries electronic parts (like Fry's or RadioShack in the US).

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  • JerikTelorianJerikTelorian Registered User regular
    edited May 2010
    ASimPerson wrote: »
    This was the first hit on Google: http://www.stevelarkins.freeuk.com/computer_interference.htm
    Here's the Wiki article about them: http://en.wikipedia.org/wiki/Ferrite_bead

    I imagine you would be able to buy these on the cheap at your favorite electronics retailer that actually carries electronic parts (like Fry's or RadioShack in the US).

    Ferrite rings have been tried, but they did me no good at all. I placed two or three of them on various cables in a variety of combinations to no effect.

    There has been a development, though. I did some science this morning and tried the speakers powered only by my UPS. Interference was minimal, even when attached to the computer. After further finagling, I found out that the cause of much of the interference is the house's ground wiring. If I place a cheater plug between the APC and the wall (thus not grounding the APC), the end result is only a minimum of static interference that I may be able to mitigate with the ferrite rings.

    The new question is whether I am endangering the surge protection by removing the grounding from my APC. If not, I suppose I'll just keep it ungrounded. If so I need some other solution.
    EDIT: Apparently using a cheater plug for this purpose is particularly unsafe. It seems that the house just has a nasty ground loop that is picking up the AM signal. My roommate's father is a retired electrician, so I will refer to him for the solution to this little mess.

    SteamID -- JerikTelorian
    XBL: LiquidSnake2061
    Spoiler:
  • FalkenFalken Registered User regular
    edited May 2010
    Try a faraday cage? Basically wrap it as much as possible in whatever they call tinfoil where you live, speakers, wire, everything. It'll look like shit, but it should work.

  • autono-wally, erotibot300autono-wally, erotibot300 love machine Registered User regular
    edited May 2010
    ferrite rings on whole cables wouldn't do no good, you'd have to place a ferrite bead on each signal line for that purpose.

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  • Rigor MortisRigor Mortis Registered User
    edited May 2010
    Tried a power conditioner? They are meant to remove radio and electromagnetic interference.

    My brother uses this one.
    http://www.furmansound.com/product.php?div=01&id=M-8x

    I use this one. Never had radio interference at your level but I can attest everything was noticeably quieter with it in use.
    http://www.amazon.com/Belkin-F9A833fc08-8-Outlet-Isolator-Protector/dp/B00154IZWK

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