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Help! High pitch ringing noise!

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  • Help! High pitch ringing noise!

    When i start my car there is an instant ringing noise in my rear speakers and this is the same for when im playing movies or just simply running windows, however if i open Everest and start a CPU stress test the noise go's away 100%

    Any ideas as to what could cause this?
    Never accept STOCK equipment.

  • #2
    it could be a ground loop. :/
    My OLD 2001 Mitsubishi Eclipse GT:
    "The Project That Never Ended, until it did"


    next project? subaru brz
    carpc undecided

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    • #3
      Ive installed a ground loop isolator and still the noise is present and when i rev my engine i can hear the noise get louder, also it sounds as though i can hear my hard drive running.
      Never accept STOCK equipment.

      Comment


      • #4
        I had a similar problem with my current project. My nettop was producing a high pitch noise. It was happening without any modifications - I just hooked it up to test it and notice that the noise was coming from the headphones. The noise changed when there was hard drive / cpu activity, and even when the mouse cursor moved across the screen. I think it's just a crappy sound card. I recommend you get a USB sound card - I've bought a couple on newegg for about $24 a piece (I needed two). They are 5.1, have Mic In and stereo Line in.
        ------------------------------------------------------------
        My Project: All-in-one Double Din Unit

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        • #5
          I have a usb sound card already and the sound is still present.
          Never accept STOCK equipment.

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          • #6
            I would try to isolate the issue by removing the unknowns one by one.
            First, hook up your car pc to a stable 12V line, not the IGN/BAT line. I'm not sure how your system is hooked up, so if you have a third party amp, you can keep the amp powered by the car, but the pc powered from an outlet (you'll need a looong power extension cord).
            If the noise is still present, plug in a set of small computer speakers (powered by a separate power supply) and see if the noise still shows up. If it does, it sounds like your usb card might be crappy. Not necessarily broken, just crappy.
            ------------------------------------------------------------
            My Project: All-in-one Double Din Unit

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            • #7
              Originally posted by nivanov View Post
              I would try to isolate the issue by removing the unknowns one by one.
              First, hook up your car pc to a stable 12V line, not the IGN/BAT line. I'm not sure how your system is hooked up, so if you have a third party amp, you can keep the amp powered by the car, but the pc powered from an outlet (you'll need a looong power extension cord).
              If the noise is still present, plug in a set of small computer speakers (powered by a separate power supply) and see if the noise still shows up. If it does, it sounds like your usb card might be crappy. Not necessarily broken, just crappy.
              The carputer is powered by a 10 gauge wire connected directly to the battery, and its a creative sound blaster 5.1 sound card. I will give the speaker test a try, thank you
              Never accept STOCK equipment.

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              • #8
                Yeah, the first and easiest test is to unplug the headphone jack that you have leading to the amp and plug in a pair of headphones. If the noise is present, then the amp is fine.
                What I meant about a stable 12V line is that you can use a 12V PSU plugged in a power outlet in your house and power your system (sans the amplifier of course) that way. If the system does not make any noise while powered from the psu, but makes noise when powered from the BATT, then it's a problem with either your PSU creating too much noise or with your carputer not being properly grounded. Ground loop isolators would remove noise if there's a difference in ground between amp and a sound card, but if the noise is generated within the soundcard, GLI's won't get rid of that.
                ------------------------------------------------------------
                My Project: All-in-one Double Din Unit

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                • #9
                  Ok

                  How do you ground the motherboard? the mount points just touch the pcb board.
                  Never accept STOCK equipment.

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                  • #10
                    That part I'm still trying to figure out myself. If your mobo is grounded through the standoff mounts, then you have two grounds - one is the mobo/standoffs/whatever-else-the-standoffs-are-attached-to, and car ground (GND wire). Mind you, I only learned about ground loops about 2 weeks ago, so I might be talking out of my ***. Maybe soundman has better advice? after all, he is sound-man
                    ------------------------------------------------------------
                    My Project: All-in-one Double Din Unit

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                    • #11


                      i was hoping you guys would search -- there is tons of info on GL's, and how to fix them.

                      nivanov is correct on grounding the motherboard-- many times the motherboard is correctly grounded through the 20/24 pin connector, so physically grounding the motherboard could cause multiple ground paths-- which is a good definition for what ground loops are..

                      i have occasionally read of certain onboard sound cards not sharing the same ground plane as the rest of the board--where the designers expected the metal pc case to be used as the connection, so motherboard grounding would be required in this case.. but the creative x-fi you have 'should' use the shield of the usb cable for a common ground..



                      many times GL's are caused by poor/dirty/incorrect connections. this could be on either the power or ground side, but the ground connection is the one that will cause the most amount of problems because it is the one that everyone neglects the most..


                      where did you attach your pc ground? did you sand the paint off? are there any other devices that share that same ground?
                      My OLD 2001 Mitsubishi Eclipse GT:
                      "The Project That Never Ended, until it did"


                      next project? subaru brz
                      carpc undecided

                      Comment


                      • #12
                        Idea

                        I used a 10 gauge wire for my 12v line and a 14 gauge wire for the ground, could this cause a ground loop? or not a good ground?
                        Never accept STOCK equipment.

                        Comment


                        • #13
                          that is a good start. your ground should always be at least the same gauge, or larger then the positive power wire. and did you sand the paint off the ground connection point?
                          My OLD 2001 Mitsubishi Eclipse GT:
                          "The Project That Never Ended, until it did"


                          next project? subaru brz
                          carpc undecided

                          Comment


                          • #14
                            sure did
                            Never accept STOCK equipment.

                            Comment


                            • #15
                              ok, sometimes when you share a ground with some factory devices, it can cause a GL, or if your amp has a different ground point then your carpc, that can also cause a GL.
                              My OLD 2001 Mitsubishi Eclipse GT:
                              "The Project That Never Ended, until it did"


                              next project? subaru brz
                              carpc undecided

                              Comment

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