static noise from psu/motherboard even with computer off

Discussion in 'PC Audio' started by drunkntigr, Nov 2, 2020.

  1. drunkntigr

    drunkntigr Member

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    had the same pc configuration, cpu, mobo, removed the graphics card recently and the computer runs off inbuild graphics.

    get static from both the onboard audio and xtrememusic card, pc on, OR OFF.

    Tried plugging pc and speakers in different outlets and still same thing.

    definitely not the audio cable.

    no interference from cables, have moved them around.

    no USB devices plugged in.

    disabled all wireless and Bluetooth signals around.

    i get the same noise even if the computer is off, sound goes way if i unplug the pc from the power. seems to be an electrical interference from the mobo or the psu.

    only thing different about the pc now is the graphics card has been removed, and I've changed the fan on the psu. i doubt it would be the fan as i get the sound even if the computer is off.
     
  2. demiurge3141

    demiurge3141 Member

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    Properly earthed?
     
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    drunkntigr

    drunkntigr Member

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    just isolated the issue

    I have both PC's plugged into the same speakers, main pc plugged via line in to the subwoofer line in input, another computer plugged into the line in on the speakers (they're Logitech z623s

    Main PC has a creative soundblaster G5, spare PC has xtrememusic/onboard audio

    when both PCs are plugged into power it seems to be causing a feedback loop, mainly because I'm guessing I've plugged two different audio sources into the speaker system.

    e.g., i have the line in of the main pc and the spare pc. having both plugged in, causes the static. if i disconnect either one, the static stops.

    anyway to isolate this? doesn't appear to be a powerpoint/powerboard/psu issue but rather just the electrical currents from both pcs is causing enough interference with each other via the audio out lines to the speakers.
     
  4. theSeekerr

    theSeekerr Member

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    I think you're describing a ground loop. A ground loop can be broken by using a 1:1 audio transformer to provide galvanic isolation: https://www.jaycar.com.au/ground-loop-noise-isolator-stereo-3-5mm/p/AA3086
     
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    drunkntigr

    drunkntigr Member

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  6. theSeekerr

    theSeekerr Member

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    No, those protect against an entirely different kind of introduced noise.
     
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    drunkntigr

    drunkntigr Member

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    ferrite chokes i mean - assume they are just for electrical cables.

    hopefully jaycar is open cup day lol.
     
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    drunkntigr

    drunkntigr Member

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    picked one up from jaycar today.

    has reduced 80% of the noise, but it's still audible so annoying af - maybe put two in the same line?
     
  9. theSeekerr

    theSeekerr Member

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    Nah, the rest of it will be another problem, the isolator 100% solves the problem it solves.
     
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    drunkntigr

    drunkntigr Member

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    edit: sound completely gone now. seems like noise disappeared once the computer booted up and into windows. assume some of the static is a windows driver issue too as the driver installation always crashes at the end.

    edit2: strange thing, when i unplug the aux cable from the other computer without the ground loop isolator, the speakers get the statis extra bad.

    i should have paid more attention in physics.
     
    Last edited: Nov 3, 2020
  11. Myne_h

    Myne_h Member

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    Assuming there's no issue with the speakers, and you test the whole setup in another house:

    You might want to check your house's earth.
    Don't suppose you're near one of those big transformer boxes?

    They're not always, but moderately commonly placed kinda close to people's yards.
    Eg:
    https://www.google.com/maps/@-38.1383859,145.2160509,3a,75y,43.9h,81.85t/data=!3m7!1e1!3m5!1sfcZlZhsmolQowKbmHlOaBg!2e0!6s//geo2.ggpht.com/cbk?panoid=fcZlZhsmolQowKbmHlOaBg&output=thumbnail&cb_client=maps_sv.tactile.gps&thumb=2&w=203&h=100&yaw=341.26978&pitch=0&thumbfov=100!7i16384!8i8192

    https://en.wikipedia.org/wiki/Earth_potential_rise
     

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