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Alternator Whining sound problem with aux input and cigarette adapter

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  • Alternator Whining sound problem with aux input and cigarette adapter

    Hey guys, need some help

    I recently installed in my scion tc 05 an AUX-in adapter which hooks into the back of the radio... in the 05's, AUX in didnt come stock.

    Now, the AUX adapter I have comes out as RCA, so i got an RCA to 3.5mm headphone jack which then goes into my android phone.

    However, If I have the android phone charging via the cigarette adapter, and I am playing music through the AUX-in, whenever I spin my engine (which is constant when I am driving) I get a whining noise...

    I don't want to use a Ground Loop RCA Adapter, because that can hurt sound quality.

    I believe there should be a way to modify my cigarette adapter, because this seems like a grounding issue. Should I ground the cigarette adapter somewhere else? If so, to what? Would this even fix the issue? It is very annoying.

    Thank you for the time
    Scion Tc 2005 RS 1.0
    Planning 50%
    Building 0%

  • #2
    i have the same thing when i connect my ipod in my car..

    the cheapest solution is to not charge it while playing music...

    otherwise, you might be able to try to pull power and ground from teh same locations as the radio..
    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
      Originally posted by soundman98 View Post
      i have the same thing when i connect my ipod in my car..

      the cheapest solution is to not charge it while playing music...

      otherwise, you might be able to try to pull power and ground from teh same locations as the radio..
      ok, but how do i find the locations of the power and ground from the radio? When I looked at the back of my radio to install the adapter, there was just one main plug, and I didn't see any obvious power cables.
      Scion Tc 2005 RS 1.0
      Planning 50%
      Building 0%

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      • #4
        Not that it's a guaranteed solution, but grounding all devices to the same point is probably the solution you are after. With adequate cable size (low resistance). And maybe decoupling capacitors (small 20c caps).

        Otherwise the isolators are used. (Or may still need to be used.)


        What is the sound quality impact of inserting an isolator - do you have the figures/specs?

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        • #5
          Originally posted by BenKenobi View Post
          ok, but how do i find the locations of the power and ground from the radio? When I looked at the back of my radio to install the adapter, there was just one main plug, and I didn't see any obvious power cables.
          by using a volt meter, and checking google for the color codes..

          Originally posted by OldSpark View Post
          What is the sound quality impact of inserting an isolator - do you have the figures/specs?
          i am very interested in this-- i don't think i have ever seen any figures specifically showing how much they degrade the audio signal.. i understand that theoretically they cause some degradation, but realistically, how much?

          but i guess that the quality of the gli would also play a huge part in this, and after thinking about it, most gli's that i have come across are a short hop from bargin-bin pricing, so they very rarely have any ratings on them at all...
          My OLD 2001 Mitsubishi Eclipse GT:
          "The Project That Never Ended, until it did"


          next project? subaru brz
          carpc undecided

          Comment


          • #6
            The reason I asked is that there shouldn't be any noticeable difference - they are usually just 1:1 audio transformers.

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            • #7
              I had this issue with my civic. (1) Anything powered from the fuse box is going to get juice from the alternator and will then be subject tot the rpm's. (2) Also car manufacturers tend to use the highest gauge wire they can (copper is expensive).

              Thin lines "leak" emi because the energy will try to find the fasted way through a circuit to a ground, even if it has to go through the air radiantly. This means you have to shield your 3.5mm to rca's well. A full 100% foil shield is preferable. And to deal with issue (1) run a new fused line to your battery to power you're cig lighter. Being that that seems to be the loose variable causing the noise. The power directly from the battery will be continuous and "smooth". You can run a relay from the original power line of the cig so that its still ACC (key) dependent power. Also beef up the cig lighter ground wire to a lower gauge (thicker line), at least the same gauge you use to feed the cig from the relay.

              Try that.

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              • #8
                Thank you for the suggestions guys, especially djvillar. Very very informative as well as helpful. Makes sense, and I think I now understand the issue. I'll find some wires and get it hooked up to the battery and I'll report back if this fixes the issue.
                Scion Tc 2005 RS 1.0
                Planning 50%
                Building 0%

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                • #9
                  One question though, what amp relay? I'm an electricity noob, really.
                  Scion Tc 2005 RS 1.0
                  Planning 50%
                  Building 0%

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                  • #10
                    I'm thinking 10 amps? I think the max output on cig lighters is 120W/12v = 10 amps?? can someone correct me or confirm?
                    Scion Tc 2005 RS 1.0
                    Planning 50%
                    Building 0%

                    Comment


                    • #11
                      yea, a 10 amp relay should be fine.
                      My OLD 2001 Mitsubishi Eclipse GT:
                      "The Project That Never Ended, until it did"


                      next project? subaru brz
                      carpc undecided

                      Comment


                      • #12
                        One question for you... Are you using the audio out of the power port on the bottom of the iphone or are you using the earphone out? If you're using the power port adapter with rca outs, try using the adpater for only power and then run audio out from the earphones and see if you get any noise... oh wait just realized your using a droid. But is it similar?

                        I'm just curious

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