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The noise is driving me insane!!

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  • The noise is driving me insane!!

    I can't get rid of this noise, I know it's engine/alternator hum cause it's exactly in tune with my gas pedal. If anyone can help point things out, I'm hoping someone can come up with something that I've missed.

    I have a pioneer avh p4000 connected to an audiopipe 1000w amp that goes to 2 speakers in the dash, 2 speakers in the front door (dash and front door speakers are connected by the factory) and 2 on the rear deck. The 6 speakers I have now, are not factory speakers, they've all been replaced.

    With this setup i experience no noise unless I turn the gain all the way up, I don't think it's necessary so I turn the gain to about 75% and keep the car noise (alternator hum) free.

    Now, I just got a no-name brand crossover/equalizer combo and when I insert it between the Head Unit and the Amp ... I get noise. Here's how I set it up.

    I connected the HU to the cross/eq via the same rca cables I was connecting the HU to the AMP. I have three 16ga wires that serve as my ground, remote and power cables. The power was connected to a power source that had multiple devices connected to it, whose source was located in the dash of the car. The ground is screwed to the chasis (bare metal sanded down) in the trunk; the ground wire is about 4ft long. The remote cable is connected to the remote socket on the Amp.

    I thought maybe a more direct power source would help, so I connected the cross/eq power cable to the Amp's power socket, no change, still noise.

    The original RCA cables shouldn't be a problem because there was no noise when the cross/eq wasn't there. I thought that maybe the RCA cable from the cross/eq to the Amp was too thin (guessing 18ga??) so I got two thick rca cables (14ga) and I was still experiencing noise.

    Now, if I turn down the gain to min on the cross/eq then there's almost no noise .... but that kinda defeats the purpose of an eq. The HU has an SNR of 97 and the cross/eq has an snr of 85 (the website I bought it from said 100). Is the problem here the SNR is too low? Any help please ....

  • #2
    Upgrade the ground wire from your battery to chasis, make sure that your RCA cables are not near your power cable. Recheck all ground wires. If all of your ground wires are good, and you still get noise, you might want to consider a ground loop isolator, it will, in most cases get rid of the 'wine' or 'hum' but not get rid of the reason it is doing it.
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    • #3
      I had this same exact problem with a pioneer headunit.

      First, i would suggest finding a better ground. If you can't, get a small wire, wrap it around the metal contacts on the Audio rca cable, and ground the other side (By attaching it to any metal part of the car). A thin wire should do fine.

      And, your noise should be gone Let me know how it works out for you

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      • #4
        http://www.mp3car.com/vbulletin/car-...ing-guide.html
        Have you looked in the FAQ yet?
        How about the Wiki?



        Under normal circumstances, a signature would go here.

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        • #5
          i think that 4" ground wire is too long.
          Try cutting down until the noise goes away?

          i had very same issue, and i eventually hAd to cut the ground wire down to a bout 4" :-(
          trinybwoy

          2006 Mazda6 Carpc

          2008 Acura TSX Nexus 7

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          • #6
            4" too long. I feel a Spinal Tap coming on. LOL
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            • #7
              Where is the battery located in the car?

              Given that that the gain affects the noise, it seems as though the RCA cable is picking up interference along the line. It may not actually be a ground loop issue, although the ground loop is definitely possible.

              A couple of quick tests to find the problem:
              Get a 3.5mm (headphone jack) to RCA cable. Connect it to an mp3 player or ipod or anything else as long as it isn't powered by the car. Connect directly to amp. Mess with the gain. Is there noise?

              Now connect to the amp through the equalizer. Mess with the gain on both. Is there noise?

              Now take the RCA cable that goes to the head unit. Detach it from the head unit, but leave it running through the car the same way it is now. You can hook it back up to the equalizer. On the head unit side plug connect the music device. Is there noise?
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              • #8
                Originally posted by NabZ245 View Post
                I had this same exact problem with a pioneer headunit.

                First, i would suggest finding a better ground. If you can't, get a small wire, wrap it around the metal contacts on the Audio rca cable, and ground the other side (By attaching it to any metal part of the car). A thin wire should do fine.

                And, your noise should be gone Let me know how it works out for you
                this doesn't always work, it can sometimes create more noise-- try this while the system is powered up, and be ready to pull the wire off as soon as you connect it..
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                • #9
                  did i miss something, no noise with out the EQ?
                  noise with the EQ
                  simple, dont use that junky EQ
                  prob poor power supply design in it

                  also, is the audiopipe amp, a 4 channel amp? and you got 2 sets of rca runs?
                  -Thanks
                  Mitch
                  www.rush2112.net

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                  • #10
                    About finding a better ground, the unit is on the trunk lid so I thought attaching it to the chasis would be better than a metal ground on the trunk lid. 4 ft might be the minimum distance to get it to the chasis while running it neatly.

                    David: I used an isolator once but it appeared that it not only isolated noise but also reduced the volume as well, so it's a possibility but maybe as a second to last resort?

                    Nab: I can try that, i have two sets of rca's behind the pioneer, and the amp also has 4 channels.

                    Triny: I could try that, but once again it's either a ground to the chasis or to the trunk lid, would it make a difference?

                    Paul: I'll try that next and try to isolate the problem a little bit further. But, what will it tell me? That the power lines that I'm running are too close to the rca cables? I don't know if I can route it differently .... so I might just have to get heavier shielding for the cables then?

                    Mitch: that's what I'm afraid of =( and ditching it is a last option ... but an option ...

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                    • #11
                      give the trunk lid a try...it shouldn't hurt .

                      I honestly think it that is the main issue.
                      I spent a long time trying to get rid of my wine.
                      and it ended up with my having to cut the ground to a few inches. I think I still have a pic of the wire lol
                      trinybwoy

                      2006 Mazda6 Carpc

                      2008 Acura TSX Nexus 7

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                      • #12
                        try grounding the rca inputs like suggested.

                        pioneers are notorious for this. they have a micro-fuse on the rca inputs, and if you do not directly ground the radio chassis itself, that fuse will pop and the radio WILL create noise. just hooking the radio up with the negative black input power wire is NOT enough. the radio chassis must also be grounded (there is a screw on the back of the heatsink for this).

                        i think it has to do with the radio pulling its ground through the rca cables when things are not properly installed. the radio works without the chassis being directly grounded, but that internal fuse will pop and you will get noise. and, in this situation, a ground loop isolator does absolutely nothing.

                        the only thing that works is to replace or bypass that fuse. dont worry about grounding the rca cables yourself, i have had my pioneer deck like that for 3 years now... it doesnt seem to effect anything.

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                        • #13
                          this the EQ also a line driver?? are the RCA's running down the same side of the car as the power wire??

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                          • #14
                            trunk lids are usually a very poor grounding point-- too many poor connections from semi-conductive grease, and moving metal parts. forget about keeping a short ground, run everything to a solid ground point on a panel that will not move in the trunk. if you have to, run a larger ground wire from the equipment to compensate for the distance.

                            most cars these days are spot welded together, which means that there might be more resistance in your particular car in a particular spot then other cars of the same model..

                            there is no end-all ground loop solution for any car or setup--even if it is the same car, or setup...
                            My OLD 2001 Mitsubishi Eclipse GT:
                            "The Project That Never Ended, until it did"


                            next project? subaru brz
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                            • #15
                              I'm with Mitch.
                              The EQ may be causing a ground loop etc. (Alternator hum - not PSU.)

                              Try a GLI.

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