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  • Strange problem

    Let me start off and say that I did search, and my problem is odd in that it is the reverse of any that I could find when searching.


    I got rid of all of my speaker noise for the most part. HOWEVER, I get alternator whine when listening to the headunit with the carputer off. If I turn the carputer on, silence. Not a hint of noise, and my amp is turned up.

    Specs are as follows:
    dell laptop, powered through invertor and ac power supply
    sony x-plod craptastic deck.
    all monster cable speaker wires/rca's
    run to a kenwood 600w amp which powers the speakers.
    All audio equipment is run to a common ground (although the deck ground is a bit long... I took it off the chassis and ran it all the way to the back with thick wire, not sure of AWG, to ground in a common spot with everything else in an attempt to get rid of the noise. Didn't make a difference. )


    The noise is only with the carputer off. It doesnt matter whether or not the headunit is on, as long as it is plugged in it makes the noise.
    The signals are mixed by a simple audio mixer (shielded) which I made on a radioshack board.
    I don't think it is my mixer because if the carputer is on, there is absolutely no noise at all.

    If I disconnect the RCA's from the deck, the noise also dissapears.


    Any ideas?
    1985 Camaro Berlinetta, black with t-tops
    500 MHZ dell CP Series
    MP3 and ALDL data monitoring/wireless internet
    kenwood 600 watt amp, powering pioneer 3 way speakers

  • #2
    Originally posted by Toehead
    Let me start off and say that I did search, and my problem is odd in that it is the reverse of any that I could find when searching.


    I got rid of all of my speaker noise for the most part. HOWEVER, I get alternator whine when listening to the headunit with the carputer off. If I turn the carputer on, silence. Not a hint of noise, and my amp is turned up.

    Specs are as follows:
    dell laptop, powered through invertor and ac power supply
    sony x-plod craptastic deck.
    all monster cable speaker wires/rca's
    run to a kenwood 600w amp which powers the speakers.
    All audio equipment is run to a common ground (although the deck ground is a bit long... I took it off the chassis and ran it all the way to the back with thick wire, not sure of AWG, to ground in a common spot with everything else in an attempt to get rid of the noise. Didn't make a difference. )


    The noise is only with the carputer off. It doesnt matter whether or not the headunit is on, as long as it is plugged in it makes the noise.
    The signals are mixed by a simple audio mixer (shielded) which I made on a radioshack board.
    I don't think it is my mixer because if the carputer is on, there is absolutely no noise at all.

    If I disconnect the RCA's from the deck, the noise also dissapears.


    Any ideas?

    first thing to do to trouble shoot it is disconnect the mixer. wire the h/u straight to the amp and then wire the pc straight to the amp.. do you still have the noise?
    New System in progress:
    M10k
    Phaze TD1500 ~> Dynaudio MD130
    Phaze TD1500 ~> Seas g18rnx/p
    Zapco Ref 500.1 ~ 12" tc-9
    Behringer DCX2496 ~ Envision Electronics psu
    Transflective Xenarc

    My Car Pc Install
    My Boat Pc worklog

    Comment


    • #3
      nope. Only with both connected does the noise occur.
      1985 Camaro Berlinetta, black with t-tops
      500 MHZ dell CP Series
      MP3 and ALDL data monitoring/wireless internet
      kenwood 600 watt amp, powering pioneer 3 way speakers

      Comment


      • #4
        Originally posted by Toehead
        nope. Only with both connected does the noise occur.

        then it has something to do with your mixer. i'm not sure how it was built or even how to trouble shoot that... hmmm anyone?
        New System in progress:
        M10k
        Phaze TD1500 ~> Dynaudio MD130
        Phaze TD1500 ~> Seas g18rnx/p
        Zapco Ref 500.1 ~ 12" tc-9
        Behringer DCX2496 ~ Envision Electronics psu
        Transflective Xenarc

        My Car Pc Install
        My Boat Pc worklog

        Comment


        • #5
          Why then does the noise only happen when the carputer is off? Should I ground the negative prong of the dc power cable which plugs into the laptop? The adapter is powered at all times.
          1985 Camaro Berlinetta, black with t-tops
          500 MHZ dell CP Series
          MP3 and ALDL data monitoring/wireless internet
          kenwood 600 watt amp, powering pioneer 3 way speakers

          Comment


          • #6
            Originally posted by Toehead
            Why then does the noise only happen when the carputer is off? Should I ground the negative prong of the dc power cable which plugs into the laptop? The adapter is powered at all times.

            just a stab in the dark but it seems as though the mixer needs two active inputs. do you have an mp3 player? try removing the laptop and plugging in the mp3 play ro the mixer see if you get the same results that you did with the laptop plugged in
            New System in progress:
            M10k
            Phaze TD1500 ~> Dynaudio MD130
            Phaze TD1500 ~> Seas g18rnx/p
            Zapco Ref 500.1 ~ 12" tc-9
            Behringer DCX2496 ~ Envision Electronics psu
            Transflective Xenarc

            My Car Pc Install
            My Boat Pc worklog

            Comment


            • #7
              Will try. Thanks for the tips, keep em coming.
              1985 Camaro Berlinetta, black with t-tops
              500 MHZ dell CP Series
              MP3 and ALDL data monitoring/wireless internet
              kenwood 600 watt amp, powering pioneer 3 way speakers

              Comment


              • #8
                Nope, no whine when connected to a battery powered mp3 player directly.
                1985 Camaro Berlinetta, black with t-tops
                500 MHZ dell CP Series
                MP3 and ALDL data monitoring/wireless internet
                kenwood 600 watt amp, powering pioneer 3 way speakers

                Comment


                • #9
                  Originally posted by Toehead
                  Nope, no whine when connected to a battery powered mp3 player directly.

                  just to get it straight you had the mp3 player and the radio hooked up to the mixer, correct?
                  New System in progress:
                  M10k
                  Phaze TD1500 ~> Dynaudio MD130
                  Phaze TD1500 ~> Seas g18rnx/p
                  Zapco Ref 500.1 ~ 12" tc-9
                  Behringer DCX2496 ~ Envision Electronics psu
                  Transflective Xenarc

                  My Car Pc Install
                  My Boat Pc worklog

                  Comment


                  • #10
                    no i had the carputer and the mp3 player hooked up....
                    1985 Camaro Berlinetta, black with t-tops
                    500 MHZ dell CP Series
                    MP3 and ALDL data monitoring/wireless internet
                    kenwood 600 watt amp, powering pioneer 3 way speakers

                    Comment


                    • #11
                      shouldn't make a difference but try the mp3 player and radio
                      New System in progress:
                      M10k
                      Phaze TD1500 ~> Dynaudio MD130
                      Phaze TD1500 ~> Seas g18rnx/p
                      Zapco Ref 500.1 ~ 12" tc-9
                      Behringer DCX2496 ~ Envision Electronics psu
                      Transflective Xenarc

                      My Car Pc Install
                      My Boat Pc worklog

                      Comment


                      • #12
                        same result. Thanks for you help though, I appreciate it
                        Keep the ideas coming!
                        1985 Camaro Berlinetta, black with t-tops
                        500 MHZ dell CP Series
                        MP3 and ALDL data monitoring/wireless internet
                        kenwood 600 watt amp, powering pioneer 3 way speakers

                        Comment


                        • #13
                          Originally posted by Toehead
                          same result. Thanks for you help though, I appreciate it
                          Keep the ideas coming!



                          fill in this chart here:
                          radio directly to the amp = no noise
                          computer directly to the amp = no noise
                          radio + computer (on) + mixer = no noise
                          radio + computer (off) + mixer = noise
                          alt. source + computer (on) + mixer = ??
                          alt. source + computer (off) + mixer = ??
                          radio + alt source (on) + mixer = ??
                          radio + alt source (off) + mixer = ??
                          New System in progress:
                          M10k
                          Phaze TD1500 ~> Dynaudio MD130
                          Phaze TD1500 ~> Seas g18rnx/p
                          Zapco Ref 500.1 ~ 12" tc-9
                          Behringer DCX2496 ~ Envision Electronics psu
                          Transflective Xenarc

                          My Car Pc Install
                          My Boat Pc worklog

                          Comment


                          • #14
                            radio directly to the amp = no noise
                            computer directly to the amp = no noise
                            radio + computer (on) + mixer = no noise
                            radio + computer (off) + mixer = noise
                            computer(off)+radio(off)=noise
                            alt. source + computer (on) + mixer = no noise
                            alt. source + computer (off) + mixer = no noise
                            radio + alt source (on) + mixer = no noise
                            radio + alt source (off) + mixer = no noise.
                            1985 Camaro Berlinetta, black with t-tops
                            500 MHZ dell CP Series
                            MP3 and ALDL data monitoring/wireless internet
                            kenwood 600 watt amp, powering pioneer 3 way speakers

                            Comment


                            • #15
                              A lot of sound cards will switch their outputs to ground when not powered. This causes the ground loop you hear. Thats why many people look for delayed turn on with their amps while the PC powers up. Its completely normal.

                              I went optical just to avoid it.
                              Take my advice: Do not try to build a system that includes EVERY feature. Start with the basics, build it to a bug free state, and THEN add on.

                              Comment

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