Loud buzzing noise when minijack is plugged to external speakers & DisplayPort to TV

Discussion in 'MacBook Pro' started by gozulin, Jul 10, 2012.

  1. gozulin macrumors newbie

    May 31, 2009
    If I plug my 13" mbp to my external speakers via minijack, everything is fine.

    If I plug it to my tv (Monoprice displayport + USB) -> HDMI adapter and I start playing any sound, a loud buzzing sound comes out of my speakers. if I stop sound playback, the buzzing sound persists for a while, then disappears.

    If I unplug the displayport and leave only the USB (which is used to power up the monoprice adapter) plugged in to the adapter, the buzzing sound still comes out.

    if I unplug the USB and leave only the displayport plugged in (the adapter is now OFF), the buzzing sound still comes out.

    If I plug in headphones instead of external speakers, there is no problem.

    This problem does not happen when I use my work's Macbook pro 15". It also didn't happen with my personal laptop before the past few days.

    Why is this happening? My laptop is still under warranty but how do I show the problem at the apple store? Any ideas?
  2. Dwhite78 macrumors regular

    Jul 30, 2010
    I had this same problem with that same adaptor. It all comes down to the fact that it's not shielded well enough and you will not be able to eliminate the buzzing. You will need a different solution.
  3. Interstella5555 macrumors 603


    Jun 30, 2008
    Spot on. Is it possible to move the computer or speakers so they are physically farther away from each other?
  4. gozulin thread starter macrumors newbie

    May 31, 2009
    But it works fine with the macbook pro 15" I tested it with!

    I will buy the newer (thunderbolt) monoprice adapter and see if the problem persists.

    I also have a miniDP to DVI adapter, so I will test it with that as well.

    They are quite far from each other as it is. about 7 feet or so. The HDMI cable is 9ft long and the minijack cable (which is plugged to an extension) is 12 ft long.

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