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  • Ohh Noise Were are tou?

    i almost give up. maybe someone has an idea what to do next?

    have a carpc with M2ATC dc to dc power supply using a SILVERSTONE DAC

    grounded pc chasis +m2atx + motherboard and even cover plate. no change still some static.

    computer uses oversized wires and all ground run to the same point. (amp + pc)

    using a ground loop isolator the high freq. static goes away (or at least is heavily reduced) but a lower frequency (id say about 15 hz) starts to appear.

    the noise is clearly carried in the USB wire and it seems as the DAC is strongly affected by it. I also tried grounding the DAC board directly which resulted in even more noise!


    im at the end of my knowledge if anyone has any ideas where to look next please let me know.

  • #2
    Originally posted by sgtpepperaut View Post
    i almost give up. maybe someone has an idea what to do next?

    have a carpc with M2ATC dc to dc power supply using a SILVERSTONE DAC

    grounded pc chasis +m2atx + motherboard and even cover plate. no change still some static.

    computer uses oversized wires and all ground run to the same point. (amp + pc)

    using a ground loop isolator the high freq. static goes away (or at least is heavily reduced) but a lower frequency (id say about 15 hz) starts to appear.

    the noise is clearly carried in the USB wire and it seems as the DAC is strongly affected by it. I also tried grounding the DAC board directly which resulted in even more noise!


    im at the end of my knowledge if anyone has any ideas where to look next please let me know.
    Don't ground to the same point....that only creates ground loops
    openMobile - An open source C# Front End (why choose openMobile?)
    - Always Recruiting Developers -
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    • #3
      well i thought about that but isnt that only true if you ground it to a point in the cars chasis that isnt properly grounded ie isnt able to conduct enough?

      with same point i meant that i ran proper gauge wires from grounds to the negative end of the battery. ie these points are not even running trough the cars frame/chasis.

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      • #4
        Originally posted by sgtpepperaut View Post
        with same point i meant that i ran proper gauge wires from grounds to the negative end of the battery. ie these points are not even running trough the cars frame/chasis.
        Thats even worse....by running long grounds like that you create a giant antenna to pick up interference. For minimal noise you want the shortest ground wires possible.
        openMobile - An open source C# Front End (why choose openMobile?)
        - Always Recruiting Developers -
        Like what you see? Donations are always welcome

        Comment


        • #5
          Try plugging a portable mp3 player or something similar into the amplifier's RCA inputs and see if the noise goes away or not. This will at least tell you if the amp is at fault or whether it is your input device to blame (in your case your PC or possibly even the DAC). Also make sure that your amplifier is not screwed directly into the vehicles sheet metal. Some amps are very sensitive to this while others it really doesn't matter.
          Data911 M5 system
          RR and iGo8PC
          Pioneer head unit
          Pioneer DEQ-9200 digital processor
          Phoenix gold line drivers
          Ultimate and Visonik amplifiers
          SMT 3 way active front stage
          Digital Design sub woofers
          3 runs of 0 gauge wire

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          • #6
            Originally posted by thewizard View Post
            Try plugging a portable mp3 player or something similar into the amplifier's RCA inputs and see if the noise goes away or not. This will at least tell you if the amp is at fault or whether it is your input device to blame (in your case your PC or possibly even the DAC). Also make sure that your amplifier is not screwed directly into the vehicles sheet metal. Some amps are very sensitive to this while others it really doesn't matter.
            the system itself Is pretty much silent...with a ipod or laptop there is no noise whatsoever... running two batteries, cap and 0 gauge wire nicely grounded to the frame.

            amp itself sits on a wooden board.

            when i plug in the USB cable in the noise starts and after a second or so when the relay of the DAC turns on it gets worse. A ground loop isolator gets rid of a lot of the noise but it can still be heard.


            I wonder if it would help to cut open the USB cable cut the power wires and feed the 5 volts from a rectified external source to the DAC?... what do you think?

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            • #7
              How is your screen being powered? I was getting a ground loop from my screen being powered by the computer, but grounded to the chassis.
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              • #8
                hmm! i power it from the PC however noise persists even when i unplug the Plug for the screen from the PC... in fact noise persist WITH ALL CABLES UNPLUGGED besides the one USB cable that goes towards the DAC....


                is it normal to get noise from DC-DC power supplies? i tought the M2ATX are made to specifically prevent that....

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                • #9
                  Originally posted by PaulF View Post
                  How is your screen being powered? I was getting a ground loop from my screen being powered by the computer, but grounded to the chassis.
                  just checked out your work paul...

                  THIS IS NOT A PROPER CONNECTION!!!! get a crimp on connector for a dollar and call it day!

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