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need help high pitch humming noise :/

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  • need help high pitch humming noise :/

    I have a 4 channel amp kicker 10z350.4 that is hooked up directly to the speakers and from there I hook my computer directly up to amp. I hear a humming noise from the speakers even before it turns on.

    I originally i hooked it up with the M4-ATX 250W power supply and I thought that it might be the power supply, so I hooked up my 850W corsair PSU and the humming noise comes out the the speakers right when i plug the power supply in (with the switch in on or off position) when the computer isn't even on yet.

    I tried this with another one of these motherboards and didn't change anything.

    When I have the amp hooked up to my phone the noise is not there what so ever and sounds really good.

    I have tried hooking my laptop up to the amp and the humming noise is not there either.

    I have tested the carpc with headphones and the humming noise is not there.

    The amp cancels the noise out when I set the crossfire or w.e. to low the noise goes away and when I have it on high or off the humming noise is there

    I have also tried it with a totally different set of y cables and that didn't change anything.

    I haven't tested it with another sound card yet and I don't really know what it could be. The sound goes away when i unplug the power supply and it also goes away right when i unplug the audio cable from the computer.

    I have the computer in a plastic container with the motherboard stands on it and also a static bag between the bottom of the container and the motherboard.

    I have been at this for awhile and this is causing me to disconnect my carpc whenever i go somewhere bc it drives me up the wall.

    Only things I can think of would be soundcard, motherboard, could the processor cause the problem (I don't think the processor is activated at all when the motherboard isn't on). As I said I have tested this with two of the same motherboards (GIGABYTE GA-880GMA-UD2H).

    btw sound is onboard and testing was done with only power and audio cables hooked up.
    2002 Honda Civic Ex --Worklog

  • #2
    well I just tested my laptop when it is plugged into the wall and the amp starts making the same humming noise, but when my laptop is using its battery and not plugged up the humming noise goes away.

    edit: the m4-atx and amp both have the same ground (a bolt with two washers and contact area sanded).
    2002 Honda Civic Ex --Worklog


    • #3
      I would guess that the soundcard and motherboard aren't grounded together well. Try doing these one at a time and see I'd you hear any difference: ground the on-board audio, ground the motherboard, ground the case chassis. If non if that works, try anther sound card pci or USB. Some on-boards are great and others seems to be the source of all noise in existence.


      • #4
        a cheap solution that might work is to run a wire from the motherboard standoffs to the same ground as the m4 and amp. sometimes the motherboards audio card needs to be grounded to prevent things like this. the other spot that you can also try grounding is the negative part of the rca cable-- sometimes this will drain the noise off the cable(same concept as the first suggestion, just a different connection point.)

        you can also try different grounding points, or a ground loop isolator.
        My OLD 2001 Mitsubishi Eclipse GT:
        "The Project That Never Ended, until it did"

        next project? subaru brz
        carpc undecided


        • #5
          thanks i'll try those ideas and see what works.
          2002 Honda Civic Ex --Worklog


          • #6
            I tried everything and nothing seems to work. I tried the ground loop isolator as well. Could the amp not be getting a good enough ground. I even tried running a wire from the bolt I have in the body for the ground all the way to the neg terminal on the battery (just to see if there would be any difference). There was not.

            I don't understand why the noise isn't there when anything connected to it is running off of a battery, but as soon as something is plugged into the car outlet or house outlet (ac) the humming noise is there.

            sry for the late response.

            ps: I have not tried a different sound card, but I have tried this with carpc, laptop, and cellphone (Galaxy S)

            edit: also If I plug up the ground loop isolator and have the amp on well the carpc is on and the ground loop isolator wether the ground loop isolator is grounded or not the humming noise still exists even when the RCA ground loop isolator isn't plugged up to the computer and when I unplug the ground loop isolator the humming noise is gone. If I plug up the rca cables directly bypassing the ground loop isolator the humming noise is still there as well.
            2002 Honda Civic Ex --Worklog


            • #7
              I had issues with several laptops / nettops (including a nettop I'm using for my current all-in-one project) and it seems that the onboard audio has an awful high pitch whine after it plays a sound. The strange thing is that if it plays a sound, the frequency of the whine changes or goes away (i assume it probably whines on a higher frequency that i can hear or my speakers can reproduce). I've experienced similar issues with laptops and sometimes this noise is somehow related to processor / hard drive activity. It might have something to do with small voltage fluctuations as hard drive spins up / down or processor kicks in full force / goes into power saving mode.

              I'm not sure of a "fix", but I just bought a 5.1 USB sound card. It's pretty cheap (~$25), supports 4 speakers and has a stereo line-in. The awful whine does not appear when I use it.
              My Project: All-in-one Double Din Unit


              • #8
                I think I might try my cuz's sound card and see if that changes anything, but unfortunately I won't be anywhere near where he lives for another week. I would hate to get a sound card and it not fix the issue :/. Also might try to hook his amp up to my car and see if it fixes the issue.
                2002 Honda Civic Ex --Worklog