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Interference between audio and VGA cable???

Discussion in 'Cables & Switches' started by feeta, Feb 4, 2005.

  1. feeta

    feeta
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    Hi,

    I have connected up a projector to my laptop via a 50m VGA extension cable.

    I have the headphones output of the laptop (3.5 stereo jack) outputting to a mixing desk then an amp, then to the speakers.

    If I play the video on my laptop but without the projector turned on, it's absolutely fine. However, when I turn the projector on, a large humm is heard from the speakers.

    If I unplug the 3.5 stereo jack from my laptop, there is no humming heard from the built in speakers.

    This leads me to believe that there is some sort of interference between the VGA and the audio cables.

    By humming, I mean a sort of buzzing, humming noise.

    Is there any way that I can stop this interference easily? eg, can I wrap one of the cables in tin-foil?

    The cables aren't actually that close together...about 30cm at their closest point, and then they go off in opposite directions

    Any help would be very greatly appreciated!

    Kind regards,

    Pete Appleyard
     
  2. Nick_UK

    Nick_UK
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    Sounds like an "earth loop"

    Try removing the ground connection from your laptop to the amp. Your audio equipment should be grounded at one point only.
     
  3. feeta

    feeta
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    Um, this may sound a little silly...what's an earth loop?

    How would my laptop be grounded to my amp? Would this be through the stereo audio cable or through the fact that both the pieces of equipment are wired in to the earth of the mains electric.

    Sorry if this is a really silly question but I am quite new to this type of stuff.

    Cheers

    Pete
     

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