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DVD player & Computer thru passive selector causing BUZZZZ.

Discussion in 'Blu-ray & DVD Players & Recorders' started by beachwail, Feb 12, 2005.

  1. beachwail

    beachwail
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    I have a 'cheap' GE 3-way passive A/V selector box.
    I use it to switch between my PC audio and DVD audio
    easily into my stereo system.
    Since hooking up my new DVD player (sony dvp-ns775v)
    the PC audio gives a loud, deep buzz. Removing the
    DVD audio from the selector box resolves the problem.

    It doesn't make much sense to me because a passive
    box should hard-wire the switch between components.

    There has to be some kind of impedance mismatch ? and
    inside the GE box there must be some resistors between
    each channel that cannot compensate for the mismatch.
    Cannot be a "true" hardwire bypass, can it?

    That is my best guess, but I really have no idea.

    Any help greatly appreciated! Feel free to ask for more
    details about my components, as there may be factors
    that I don't realize contribute to the BUZZ.

    The components:
    * * * * * * * * * * * * * * * *
    Dell PC - Soundmax Digital Audio soundcard
    Monster Standard THX-cert RCA-to-1/8" stereo cable.

    Sony dvp-ns775v
    Esoteric Audio Musica 100 RCA cable.

    GE 3-way selector with red, white, yellow RCA jacks for each.
     
  2. KraGorn

    KraGorn
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    It's not an earth loop is it?
     
  3. beachwail

    beachwail
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    Upon further research and your suggestions, I would say it is definitely an earth loop. How do I isolate the grounds?

    Typically in my electric guitars a "star ground" works best for eliminating hum, where all grounds meet at one point, versus the "daisychain" method. Should I take apart the GE switcher and see if I can re-route the ground wires?

    Still, I suppose that does not solve the issue because the grounds are still looped. Do I need some sort of "active" device to isolate them?

    Thanks for the feedback--hopefully you guys can help me rectify this.

    Cheers!
     
  4. KraGorn

    KraGorn
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    While not the only cause by any means, one of the easiest ways to get a loop is to use more than one mains socket, thus causing the loop via the mains supply branches throughout the house .. your experience with guitar systems mirrors my own, the 'one socket' approach approximates to that.

    As you may have done with your music gear, sometimes a loop is broken simply by disconnecting an earth at one end of low-voltage connector, the same thing can be done here if you're unable to sort it out any other way.
     
  5. beachwail

    beachwail
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    The grounds are not connected to anything inside the switcher.

    I'm lost of ideas at this point---

    Any help? I can send pictures if necessary.
     
  6. KraGorn

    KraGorn
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    Surely the shields on the cables are connected to the shell of the switcher and thus to each other?
     

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