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Terrible Audio Hiss and Engine whine noises - Help

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  • Terrible Audio Hiss and Engine whine noises - Help

    Before I ask, I did do a

    Having problem with audio. Just completed my install and here is what I have:



    I built in a manual switch, which controls the 12V going from CarPC to relay, so that I can switch "on" to CarPC, or I can switch "off" to HU.

    So, whenever I switch to the CarPC, all I hear is terrible, terrible interference, hissing and engine whine, but it is fine when relay is switched to HU. If I accelerate, I can hear it thru the speakers as whinning. Even the harddrive spinning creates interference sounds. The only time I hear music is if I turn the volume on my carPC up all the way, where it muffles the sounds...

    I used radio-shack RCA cables and RadioSHack y-splitters for the section going from relay to CarPC. Also, there is a small section of the relay, where I had to use 22+ gauge wires..

    WOuld changing all the wires to shielded high-quality wires work? PLease help
    ----------------------
    C134 Case
    VIA EPIA M10000
    FrodoPlayer
    iGuidance + GPS
    7" touchscreen LCD
    2000 Mitsubishi Eclipse GT
    - V6 216hp
    - KYB-AGX adjustable struts
    - Konei Alloy 17" rims + Pirelli P-Zero's
    - AEM slotted brakes
    - AEM CAI

  • #2
    Originally posted by sxt173
    I used radio-shack RCA cables and RadioSHack y-splitters for the section going from relay to CarPC. Also, there is a small section of the relay, where I had to use 22+ gauge wires..

    WOuld changing all the wires to shielded high-quality wires work? PLease help
    OUCH!

    I would consider going and buying a good set of RCAs, keep your reciept.

    Plug them in (run them above the carpet even) drive around for a while and see if it makes it better.

    Also, keep in mind that electronics do have a break in period. When I first installed everything in my car I got a slight hum at higher RPMs, a few days later (a few hours on the equipment) and it's gone....SQ judge didn't even detect it. Check your grounds, most of the time noise like this is caused from a ground loop.

    Where do you have everything grounded? At the same spot? If the same spot wasn't possible, did you try and minimize the numeber of grounds? At the points where you did ground your equipment, did you make sure that it was a SOLID ground? I'm talking scraped away all the paint and made sure it was METAL to METAL contact? And that the contact was constant?
    Jan Bennett
    FS: VW MKIV Bezel for 8" Lilliput - 95% Finished

    Please post on the forums! Chances are, someone else has or will have the same questions as you!

    Comment


    • #3
      Originally posted by Red GTi VR6

      Check your grounds, most of the time noise like this is caused from a ground loop.
      What's a ground loop? Haven't heard of this before

      Originally posted by Red GTi VR6

      Where do you have everything grounded? At the same spot? If the same spot wasn't possible, did you try and minimize the numeber of grounds?
      My CarPC is grounded "clean". Everything else on the system, i.e. monitor, relay, etc is plugged directly into 12V and grounds coming off of CarPC.

      Btw, the sound is not just a hum, its an almost unbearable distorted noise. I think I'll also try seperating the audio and power cables, as they are all bundeled together right now and are running along side each other (could cause distortion)
      ----------------------
      C134 Case
      VIA EPIA M10000
      FrodoPlayer
      iGuidance + GPS
      7" touchscreen LCD
      2000 Mitsubishi Eclipse GT
      - V6 216hp
      - KYB-AGX adjustable struts
      - Konei Alloy 17" rims + Pirelli P-Zero's
      - AEM slotted brakes
      - AEM CAI

      Comment


      • #4
        Originally posted by sxt173
        Before I ask, I did do a

        Having problem with audio. Just completed my install and here is what I have:



        I built in a manual switch, which controls the 12V going from CarPC to relay, so that I can switch "on" to CarPC, or I can switch "off" to HU.

        So, whenever I switch to the CarPC, all I hear is terrible, terrible interference, hissing and engine whine, but it is fine when relay is switched to HU. If I accelerate, I can hear it thru the speakers as whinning. Even the harddrive spinning creates interference sounds. The only time I hear music is if I turn the volume on my carPC up all the way, where it muffles the sounds...

        I used radio-shack RCA cables and RadioSHack y-splitters for the section going from relay to CarPC. Also, there is a small section of the relay, where I had to use 22+ gauge wires..

        WOuld changing all the wires to shielded high-quality wires work? PLease help

        From Deerfield Laboratory:

        Ground Loop Noise

        Hum and crosstalk are likely to occur when the elements of an electronic system are connected by transmission lines. Ground return paths generally exist which are external to the ground conductor of the transmission line. (The braided shield is the ground conductor on a coax line). Noise energy is introduced into such a loop by way of an equivalent generator in the ground return path, or by magnetic induction into the ground loop. If ground potential differences in the AC power feeds are the cause, then hum results. If the noise source derives from another line, then crosstalk results. Long distances between ground points, poor grounding practices, and inherently compromised grounding environments increase the probability that ground loops will cause interference.

        So to correct this problem get a Ground Loop Isolator like this one:

        http://www.radioshack.com/product.as...t%5Fid=270-054


        Sxt173 I would like to know more about you manual Switch 'cause I really have a good HU and I would like to keep my factory Amp....

        Can you post the components and if is possible some links where you got the parts from to build this switch (What relay and more details of you project)

        Thanks in Advice....
        RexBruMet Skin for FrodoPlayer

        Nissan Aux-in MOD


        Originally posted by bgoodman
        We're an international forum, post in whatever langauge you like.

        Comment


        • #5
          Thx for the info. Here's my info on the relay and the way I set it up (btw, I got some advice from a professional audio install shop)

          The relay is a standard relay from radioshack
          Link to radioshack site with item

          So, I have FL, FR, RL, and RR speaker cables going to my factory amp. I hooked these up to the relay coming from the headunit to the amp, in the off position. Then I simply spliced a cable coming out of my ATX power supply on the CarPC. This cable + ground (which btw is spliced off of the plug that powers my harddrive) sonnects to the 12V input and ground of the relay. So when computer is on, CarPC supplies 12V constant and switched to CarPC speaker wires going to amp, when CarPC is off, it switches to headunit.
          I added a manual switch on the ground wire coming from CarPC to relay, so that I can manually simply throw a switch and switch from headunit to CarPC.

          In my setup, the amp is always getting its 12V signal and ground from the headunit, I am simply switching the speaker wires from CarPC to Headunit and back. Important thing is that Relay off position is headunit, and on position is CarPC, where I simply put a manual switch in between, so I'm not forced to get CarPC audio every time CarPC is on.

          Let me know if you need more info.
          ----------------------
          C134 Case
          VIA EPIA M10000
          FrodoPlayer
          iGuidance + GPS
          7" touchscreen LCD
          2000 Mitsubishi Eclipse GT
          - V6 216hp
          - KYB-AGX adjustable struts
          - Konei Alloy 17" rims + Pirelli P-Zero's
          - AEM slotted brakes
          - AEM CAI

          Comment


          • #6
            Originally posted by sxt173
            I think I'll also try seperating the audio and power cables, as they are all bundeled together right now and are running along side each other (could cause distortion)
            Yeah, that will help. I had some noise coming from the carputer after bundling the audio and power wires in the same bundle. I separated them and it helped. But I didn't have an unbearable noise, just the alternator whine that went up in pitch as you accelerate.

            Check out "ground loop isolators". They may help. There is also a nice explanation of ground loops on the Wikipedia.
            Originally posted by ghettocruzer
            I was gung ho on building a PC [until] just recently. However, between my new phone having internet and GPS and all...and this kit...Im starting to have trouble justfiying it haha.
            Want to:
            -Find out about the new iBug iPad install?
            -Find out about carPC's in just 5 minutes? View the Car PC 101 video

            Comment


            • #7
              ummm...yeah - seperating the power and signal is normal practice in car audio, , especially when using lower quality RCAs.....that's pretty much a necessity
              Jan Bennett
              FS: VW MKIV Bezel for 8" Lilliput - 95% Finished

              Please post on the forums! Chances are, someone else has or will have the same questions as you!

              Comment


              • #8
                OK, this is what I tried:
                1. Plugged in speaker cables directly to iPod, no interference, works great
                2. Plugged headset into computer, no interference, works great
                3. I plug speak wires back into computer, awful hiss.

                Note, when I had the iPod plugged into speaker cables, the relay was still being powered from the PC 12V cables and the speaker wires were still running along the same path as they are when they are plugged straight into the PC.

                So, odd problem, my setup works fine when anything but the PC is plugged into it. PC is working fine though, as I tried it with headsets... I'm about to shoot the computer, or the dashboard!!!
                ----------------------
                C134 Case
                VIA EPIA M10000
                FrodoPlayer
                iGuidance + GPS
                7" touchscreen LCD
                2000 Mitsubishi Eclipse GT
                - V6 216hp
                - KYB-AGX adjustable struts
                - Konei Alloy 17" rims + Pirelli P-Zero's
                - AEM slotted brakes
                - AEM CAI

                Comment


                • #9
                  This should take care of your problem, Ground your pc case to the ground point on your automobile. I had this problem with my inverter, ground the inverter case, no noise, and one happy camper

                  Comment


                  • #10
                    that is a great idea, but 1 small problem. My PC case is plexiglass... so maybe ground a metal part of the MoBo? Like the metal part off of the speaker jacks?
                    ----------------------
                    C134 Case
                    VIA EPIA M10000
                    FrodoPlayer
                    iGuidance + GPS
                    7" touchscreen LCD
                    2000 Mitsubishi Eclipse GT
                    - V6 216hp
                    - KYB-AGX adjustable struts
                    - Konei Alloy 17" rims + Pirelli P-Zero's
                    - AEM slotted brakes
                    - AEM CAI

                    Comment


                    • #11
                      The best place to ground your motherboard when using a plexiglass case is the metal area around the screw holes where you mount the motherboard.
                      My 1967 Mustang
                      CarPC in progress

                      Comment


                      • #12
                        The headset test cinches it. You have a ground loop. Properly grounding the mobo will help. As suggested, use the metal around the screw mount holes, ground everything to the same location. If it persists, look into getting a ground loop isolator.
                        Originally posted by ghettocruzer
                        I was gung ho on building a PC [until] just recently. However, between my new phone having internet and GPS and all...and this kit...Im starting to have trouble justfiying it haha.
                        Want to:
                        -Find out about the new iBug iPad install?
                        -Find out about carPC's in just 5 minutes? View the Car PC 101 video

                        Comment

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