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strange noise coming from HU (sounds like I can hear the CD spinning?)

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  • strange noise coming from HU (sounds like I can hear the CD spinning?)

    I have a pioneer DEH-P7700MP headunit with an infinity REF7541A 4 channel amp, and infinity reference speakers.

    I play CD's full of mp3's (encoded at 192kbit or higher). it sounds like I can actually hear the CD spinning up through my speakers, and other weird sounds.

    what would cause this? a bad ground somewhere (probably need a better ground for the HU?)

    would I need a ground loop isolater?

    thanks for the info!

  • #2
    My guess is that you are using a the speakers outputs from the deck to the highlevel inputs of the amp. If not then disregaurd the rest.

    Some people tend to like the effect using the high level inputs on their amps make the total signal a lot louder. In my opinion it causes more distortion and over drives the amps.
    I had a car recently that had a factory amp, and it was doin the same sounds of the CD spinning. What may be happening is low level noise i.e. from the CD spining can be picked up by the signal. But these noises from the radio are very minute and dont increase when the volume is increased. In the case I had, all I did was bypass the factory amp and run the deck straight to the speakers. In your case you'll have to run RCA lines from the radio to the amps.
    "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"

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

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    • #3
      i'm not too keen on audio installs, and don't know if i'm' using the high level inputs or not...

      but I have 2 pairs of RCA cables running to my 4 channel amp... 1 pair for the 2 front speakers, and 1 pair for the 2 rear speakers. i then have a thick guage speaker wire running from the amp to all 4 speakers..

      don't know if this helps out any

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      • #4
        To follow up with the OP on this issue, I have the same symptoms..and I have a pioneer 570mp (or 560mp..i forget lol).

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        • #5
          looks like a bad batch of pioneer HU. I'd suggest get a new headunit.

          Side note you are not using the high level signal from the HU, you are using the pre-outs. I dont think that a ground loop isolater would do the trick, because its imbedded in signal lines and shouldnt be a case for the faulty install. Its worth a try. Also try regrounding your amp and HU and attach a ground wire between the amp and the HU. usually some rca wires have a separate wire attached just for that.
          "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"

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

          Comment


          • #6
            I have a PMP8500 and it does the same thing too. It's not very loud so it doesn't bother me too much. Must be a pioneer thing. I'm going alpine next time.

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