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    Headphone buzz weirdness

    Discussion in 'Dell' started by deadsimple, Sep 4, 2007.

  1. deadsimple

    deadsimple Notebook Consultant

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    Many of us have experienced the headphone buzz with the latest Dell models, but I noticed something weird the other day with my Vostro 1400, which made me question the whole issue.

    My setup:

    Mains -> PC -> Audio Amplifier -> Headphones
    Mains -> AC adapter -> Laptop

    Basically I was listening on my noise-canceling headphones (battery operated) to music from my PC and not the laptop, while typing on the laptop with the AC adapter connected.

    Every time my hand got near the laptop, I could hear that distinct buzz on my headphones, as if they were directly plugged into the laptop (and not the PC). Pull my hand away and the noise stopped.

    So I tried several things:

    1. Unplugging laptop AC adapter: noise gone. Reconnecting it: noise starts again (as expected).
    2. Amplifier turned off and unplugged from wall, headphone still connected: noise still present!
    3. Amplifier turned off and unplugged from wall, headphone unplugged and floating: noise gone!

    Keep in mind these are quite expensive noise-canceling headphones and not some cheap, noisy ones. And no I'm not going to use gold-plate connectors, go away :p

    Most of us know that the buzzing is related to the AC adapter, but this to me also points to some huge EMI issue surrounding the entire laptop which my amplifier managed to pick up, and not just limited to the headphone jack (which I wasn't even using!)

    Any thoughts? If anyone has noise-canceling headphones, plug them into an amp and hover your hand a cm/inch from the laptop and confirm my observation!
     
    deadsimple, Sep 4, 2007
    #1
  2. brandonjp

    brandonjp Newbie

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    I've spent the last few months testing and testing and just finally figured out last night that the buzz from my rig was because of the AC adapter. My setup is as follows:

    Dell 5100 > M-Audio FW410 Audio Output > Sound System

    and whenever the AC adapter is plugged in it's the most horrific crackling and popping, but unplug it and everything pristine and clean.

    So...is it a problem with every Dell AC Adapter like this, or is there something else I can try. I've spent too much money beefing up this computer for audio production to let this little adapter ruin everything!!

    Any tips?
    thanks
    --bp
     
    brandonjp, Sep 5, 2007
    #2
  3. neilnpatel

    neilnpatel Notebook Evangelist

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    bump, any answers
     
    neilnpatel, Jan 12, 2008
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  4. hypdotspec

    hypdotspec Notebook Evangelist

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    could have to do with the fact that the motherboard is not properly ground.

    The screws holding the audio jack together on the 1400 should have insulation on the heads to prevent contact with the card and motherboard - however they are not.

    search for a post by n19htmare which details the problem in full, and offers a guide on fixing it
     
    hypdotspec, Jan 12, 2008
    #4