09 Quad: Speakers picking up radio?

Discussion in 'Mac Pro' started by whyrichard, Nov 25, 2009.

  1. whyrichard macrumors 68000

    Joined:
    Aug 15, 2002
    #1
    Hello,


    My speakers hooked up to my 09 quad are picking up a distant radio station.... this doesn't seem to happen when i'm in bootcamp....

    ... how do i avoid this?

    thanks,
    r.
     
  2. whyrichard thread starter macrumors 68000

    Joined:
    Aug 15, 2002
    #2
    it is actually present in both windows and mac sl...
     
  3. smacman macrumors 6502

    Joined:
    Feb 7, 2006
    #3
    Poorly shielded speaker circuitry / poorly shielded home AC power wiring or both...
     
  4. whyrichard thread starter macrumors 68000

    Joined:
    Aug 15, 2002
    #4
    hmmmm.... the speakers are monitors, advent, decent quality... how do i work around poorly shielded ac power wiring? try a different outlet?
     
  5. gfhoward macrumors member

    Joined:
    Oct 6, 2009
    #5
    Hey whyrichard, it's interesting, I'm going through the exact same thing right now. I've never had speakers pick up RF interference in my home before, but my new Swan M10s are playing a radio station, even when they're not connected to my 09 Mac Pro!

    My guess is the interference problem has nothing to do with the Mac Pro, and more to do with the fact that most computer speakers are poorly shielded. Anyways, I'm happy to share with you what I'm learning about how to solve the issue, and I'll keep you up to date on the solution I find.

    First, try these diagnostic exercises, just to isolate the problem area further.

    1) Disconnect speakers form Mac but keep them powered, volume about midway. Still hear the radio? If so, it ain't the Mac

    2) Try plugging and unplugging RCA cables to/from speakers and any main amp unit (in my case, the amp is built into the subwoofer box). If no change in interference, then the power line is the main cuplrit

    3) Try plugging the speakers into a UPS, and/or a different outlet. Still hear the radio? Is it a different station than before? Sometimes a UPS' transformer will provide enough shielding for the interference. If a different outlet plays a different station, it's definitely a power-line wiring issue.

    Solutions:

    Let me know how your diagnostic tests turn out, but here are some fixes. Some are easy but may not totally solve it, other solutions are more complicated but should do the trick. I've tried to order them in order of ease to difficulty.

    1) Try re-positioning the speakers, and especially any main sub or amp unit (basically the one the power cord goes into) on a different part of the desk, or other side of the room. Try a different outlet, or a UPS.

    2) Change the channels on any wireless devices/electronics in the house

    3) Keep units away from any wireless devices such as wireless modems and cordless phones.

    4) Do not let the speaker cables run parallel to the power cable. Cross them at 90 degree angles, or even better, keep them separated from each other.

    5) clamp ceramic ferrite rings on power and speaker cables, close to the amp

    6) upgrade cables like RCAs to better-quality well-shielded variety

    7) shield the speakers with aluminum foil by wrapping along their backs or backs and sides

    8) Install a power line filter between the outlet and the speaker's power cord. This could be a Radio Shack transformer, but I recommend something else. Check out http://www.lcr-inc.com/osc/ for their general purpose power entry filters and single phase filters. I'm in the process of soldering a power cable to one of their power entry filters,
     
  6. whyrichard thread starter macrumors 68000

    Joined:
    Aug 15, 2002
    #6

    thank you that was very helpful!

    r.
     
  7. whyrichard thread starter macrumors 68000

    Joined:
    Aug 15, 2002
    #7
    so I tried rewiring the speakers in relation to the computer and their power supply, the radio sound was reduced but it did not go away.

    Later I realized wearing headphones that I can hear the same radio frequency through the headphones! --does that mean that the mac's power supply is the main culprit? in which case the 'power line filter' you speak of is necessary?

    thanks a lot,

    r.
     
  8. gfhoward macrumors member

    Joined:
    Oct 6, 2009
    #8
    OK. You and I have slightly different problems, as I don't get a radio signal by plugging headphones into the computer. In my case, the interference is not coming through the computer, it is purely in the speaker set, its wiring, or in my home electrical wiring. In your case, are you using a UPS between the outlet and your computer? If you are, it is more surprising you have this problem, as most UPS modules filter the power signal. But if you are, then the UPS and the speaker set should both be filtered with the appropriate power line filter. However before you do that, I would try upgrading all cables to the and between the components of the speaker set to triple-shielded high-grade cabling, and moving the amp/sub around the room, or if you don't have an amp/sub, then the satellites.

    If you're not using a UPS, then it is likely the wiring in your home that is acting as the antenna. In that case, a power line filter between the outlet and the speaker set should do the trick, although I still recommend switching the cables and moving the components around.

    What speaker set are you using?
     

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