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Thread: Please help! PC strange behavior, audio hiss, ground loop etc.

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    Default Please help! PC strange behavior, audio hiss, ground loop etc.

    Hi folks. I'm here because I hear that you guys are the best in the biz when it comes to troubleshooting power supplies and electrical related issues.
    I'm at the absolute end of my wits here and I've tried everything I can think of as to why I'm getting these strange issues.

    Some weeks ago I finished building a brand new PC.

    Here are the components of my audio setup.



    Here is the whole thing together:



    Note that all the AC cables and speaker/RCA cables are separated, so they are not overlapping or too close together in order to introduce interference. The Supra cables are meant to be really well shielded and resistant to EMI anyway.

    Everything went together pretty smoothly although I did manage to bend 2 CPU pins. With a lot of patience and some effort I put them back to the point where I couldn't even tell they had been bent. The bending wasn't terrible in the first place, but they weren't straight either. After leaving my machine on overnight doing a stress test for a total of 2 nights in a row to test if everything was stable, I was pretty satisfied that everything was working well and temps and performance were nominal.

    Until I received the final part of my machine. My Creative Soundblaster AE-9PE. This is where the problems have started.

    Upon plugging that into my amp, I was met with horrible buzzing through my speakers at any volume above 40% (on my amp). Regardless of what the audio level is set to in Windows.

    Additionally, if I switch the mains/outlet on, thus putting power through my PC/motherboard/etc and causing the motherboard light to be on but without actually powering it on fully, I get a horrible noise through the speakers, and even at 40% volume on the amp the sound is horribly loud. The noise stops at this volume level as soon as the machine is powered on fully. However, buzzing can still be clearly heard if I turn the volume up above 40% on the amp. Adjusting the volume level via Windows 10 does not make any difference what-so-ever to eliminate buzzing.

    Strangely, if I shutdown the PC, as soon as the device shuts down the buzzing stops. Despite the fact that the PC/motherboard/etc. still has power going through it and the motherboard light is still on.

    This problem means:

    1. I cannot have my amp on, but PC set to powered off (but still with power running through the machine via mains/PSU switch being set to ON)
    2. I cannot turn the volume up above 40% on my amp unless I want to hear buzzing

    I have tried (all with no discernible difference at all):

    1. Different RCA cables (Supra 5m Dual RCA-6 and Supra 10m Dual RCA-6) for the connection between my amp to my PC
    2. Different power cable for my PSU
    3. Plugging all devices into an adapter and then plugging the adapter into a singular outlet, as to try and eliminate possible ground loop.

    What I have not/cannot try:

    1. Different speaker cables/banana plugs (I don't have any)

    Any help in eliminating this buzz would be greatly appreciated.

    EDIT: Currently uploading videos and audio clips of the issues.
    Last edited by whyaudiowhy; 3 Weeks Ago at 12:29 PM.

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    Default

    There is a ground connector on the back of the amplifier, did you try that?
    Last edited by ashiekh; 3 Weeks Ago at 12:33 PM.

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    Default

    Quote Originally Posted by ashiekh View Post
    There is a ground connector on the back of the amplifier, did you try that?
    That ground is for the phono ports if you plug in a record player.

    But it's easy to tell if it can help. Just put your finger on the screw and see if the buzz goes away.

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    Default

    Thanks a lot for the replies. I touched the screw whilst grounding myself and nothing changed, there is absolutely no difference what-so-ever.

    Any other ideas?

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    Use foil shield (or shield wire if equipped - verify continuity with shield) as the ring conductor. This might help if the noise level is independent of the output level of the sound card.

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    Problem solved.

    My TV's antenna cable was connected to the wall. It obviously has a different ground to the rest of the wiring in my house, I think maybe even it's slightly electrified to improve signal quality too. This was causing feedback/ground loop through my TV into my wiring and then into my amp and speakers. As soon as I unplugged the TV antenna, the buzz stopped completely.
    I don't even watch free-to-air anyway so I just unplugged it.

    God I was going to RMA each of my computer parts one by one, what trouble this saved!

  7. The Following 2 Users Say Thank You to whyaudiowhy For This Useful Post:

    ashiekh (3 Weeks Ago), Jon Gerow (3 Weeks Ago)

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