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inteference in audio

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  • inteference in audio

    so let me start of by saying i am a car audio installer and now i am stumpped at a ground loop issue. first i have to replace my blower motor in my car and that involved removing the complete dash. while it was off i cleaned up all the wiring in the car. when i put it to gether i have a horrible whine like i have 7 turbos spooling up. i started by, removing the rca cable and running a new wire and got same issue. ran new ground to radio same prolem. ran a new power and ignition same problem. ran new power, ground and ignition from a test bench same issue. ran new power from direct battery and ground same problem. tested amp with clean power source and helped a little. tried ground loop isolator same problem. tried ground rca in front and rear same problem. in the end i touched the outer part of the rca connection of the rca to the deck and BAM all whine gone. but why i am happy i figured out the problm but what is causing it. my rca wire has so much ground in it i can run the radio ground of the rca and the damn radion turns on. the antenna is not even plugged in. so what is causing so much ground in the rca.


  • #2
    did you test out the ground differential and the voltage difference between the amp ground and the radio ground. By that i mean test the impedance between the gound points and the voltage difference between each constant and each ground points.
    "In the beginners mind there are many possibilities, but in the experts mind there are few."- Shunryu Suzuki
    "Do it right or don't do it at all"

    [-------90%-] (New Car=New Build)


    • #3
      You may hve blown the rca grounds either in the amp or HU. We have seen this quite often. The Printed circuit foil in the amp or head unit opened or burnt up. The main cause for this is when the amp does not have a good power ground. The amp then uses the ground supplied via the RCA connector back to the head unit. The ground foil on the PC board is not robust enough to carry the load from the amp so the foil opens up somthing like a fuse.

      This happens 9 out of 10 time aat the head unit and not the amp. The only way to fix it is to restore the ground (Outer Ring) of the RCA at the blown component. This involves opening up the blown component and soldering a wire from a ground point on the PCB directly to the Outer rings of the RCA connectors.