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BAD engine intereference PLEASE HELP

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  • BAD engine intereference PLEASE HELP

    I have a farenheit dvd player hooked up to my alpine cda-9827 through and aux-input and also to my lcd tv screen. At first my dvd player was plugged into my cigarrette lighter until a local audiophile told me this is the noisiest place in the car, then i tried hooking it directly to the battery and grounding it the the car body with a self tapping screw. That helped a little bit, but not much so i just tried the last thing i could think of, i spliced the positive and negative wires inline with the positive and negative going into my head unit, this also helped minimally, i also have the power wires hooked up to a 20 amp heavy duty noise filter which helps some. The sound i get is an irritating high pitched whine that increases in frequency with the engine rpms, this sounds is not noticeable when my headlights are off but gets extremely bad when my lights are on making it impossible to watch movies at night, or when it's raining, or when it's cloudy, you get the picture. I even had my alternator tested but it was fine also. I am out of ideas here, any help or suggestions would be greatly appreciated. Thanks in advance!

  • #2
    You will need this Ground loop isolator

    That will take the interference out from the rca lines. Check also your amps grounding.
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    • #3
      Me too..

      Well the most obvious cause of amp interference has to be when wiring the linesignal-cable close to or even along the ampīs power cable(s)..
      In my, and most other carPCs the puter is in the back with the amps, so this fairly short cabling shouldn't be the problem.
      My problem is also the humming or summing or what you may call it. Mine just isn't caused by audio-cabling but apparently by my lilliput monitor somehow.. When i unplug the connector from the monitor all humming dissapears. Very strange..
      I will need to look at my groundings and hunt down the source for this..

      Well, good luck getting rid of this most irritating sound..! - Kinda sounds like having supercharged the f*** out of the engine..

      - Denmark


      • #4
        i've tried a ground loop isolator and it makes the sound worse, also i don't have an amp but the dvd player's power wires and rca cables are on opposite sides of the car so that probably isn't the problem either, any other ideas?


        • #5
          Is the audio out on your DVD player a headphone jack ?


          • #6
            no the output is rca i have the audio split and running to my head unit and tv with rca cables


            • #7
              Have you tried grounding the DVD audio to the Heaunit audio ?


              • #8
                yes it is grounded with the head unit and also gets it's power from the same line as the headunit


                • #9
                  man, my friend's amp does kinda sounds cool but after a while its annoying as he speeds up on the highway it sounds like a ghostbuster's power pack charging up
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                  • #10
                    Originally posted by shades1315
                    yes it is grounded with the head unit and also gets it's power from the same line as the headunit

                    The audio ground...not the power ground ????


                    • #11
                      Originally posted by Matthew230
                      The audio ground...not the power ground ????
                      Okay I am getting slight whining, that's how I got to this thread.

                      I need this explained.. isnt audio ground and power ground the same?

                      When people say "ground your amp to your preamp and your pc" do they mean audio or power ground?

                      I notice I dont get any whining when the carpc is connected directly to my amp, but when I have the preamp in between, i get slight whining.
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                      • #12
                        It sho iz not....

                        Some amplifiers have isolated ground systems where the audio ground is seperated from the power ground.

                        My advice is to start simple. Pull out the Y connector and plug the audio cables directly into the head unit. Is there still noise? Plug it into the TV, is there noise now where there wasnt before? I have to warn you that the components of that DVD player are on the low end and subject to noise issues like this.

                        Basically what I am saying is start cutting out variables and see what happens. Locate the noise source and then work from there.
                        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.


                        • #13

                          check this out guys... i have my carpc audio (SB USB) connected to a Sony Auxilery adapter going into my sony aftermarket HU. The auxilery adapter is from logjamelectronics and how it works is it has to have the CD changer connected to it in order to get any auxilery audio to work ( So i have my cd changer RCA cables going into the adapter which then goes into the HU. The adapter is grounded to the dash metal chassis. The pc audio from the soundblaster usb sound card is going RCA out to the RCA in's on the aux. adapter.

                          The Problem: Im getting that darn engine rev. whine/noise coming outta my speakers when i use EITHER the cd changer audio or the pc audio (however, the cd changer noise is even louder).

                          The weird part: when i unplug the carpc audio from the equation , i STILL get the hiss/whining noise on my speakers.

                          Anyone have any ideas what it could be? im starting to think its the cd changer RCA cables ...(crappy or unshielded crappy cables)

                          thanks guys
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                          • #14
                            There are too many different problems here to address each one so I will try to simplify this for you guys. This is how I wire all my installations that involve multiple pieces of electronics (keep in mind that I have done this at least a 1000 times). First, I run a power wire directly from the battery to the rear amp. Then a power and ground wire from the rear power supply line to the front of the car (generally the head unit and stuff is here modify this for other installs). I do not use a direct ignition wire for anything. I wire a relay to change constant power into ignition power. I use the power wire ran from the rear to front to power the relay and electronics. I use the ground wire from the rear to ground everything. Keep in mind the current draw to determine the wire gauge needed. Then I use a digital multi meter to test for a good ground location in the rear. Once I find the ground location I ground everything to this point...all amps,head units,eqs, and such. Only thing that does not get grounded there is relays.

                            I hardly ever have noise...1 in 20 installs. Over 15 years that is pretty good. Also I never use ground loop isolators. If you take the time to find the problem there is no need for one.

                            How to wire the relay to switch ignition. 85 goes to ignition, 87 constant 12v, 86 to ground and 30 to radio ignition lead.

                            How to test for a good ground with a digital multi meter or VOM. Set the meter to continuity or impedance (measures in Ohms). You will need a long piece of wire to get from the front of the car to the rear of the car. You will also need to either ZERO OUT the meter or take into account the resistance of the wire. Attach the wire between the two contacts. Zero out the meter or write down the amount of resistance the wire has. Now attach that piece of wire to the negative lead of your VOM and the other end to the negative battery terminal. Take the positive lead and touch it to potential or current ground locations. The impedance should be as low as possible. The higher the number the more likely you will have noise in the system. You can use this procedure to test a current ground location or to find a new one. Let's say you find a ground location you know should be a good one. Like the frame of the car. Your meter reads high impedance. You can then change out the factory negative cable or add another cable to the factory line. Make sure the cable has a good clean and tight connection to the battery and chassis ground. This will lower the resistance to the rear ground location. Using this procedure combined with proper wire gauge sizes will allow maximizing ground locations and minimizing possible noise injection.

                            When you have multiple pieces of electronics and noise it is often best to determine which piece of electronics is causing the noise. Start by removing products one at a time. If there are electronic EQ's or xovers bypass them. Eventually you will find the piece that is making the noise and be able to concentrate on the piece.

                            I have never found a noise in a car that could not be removed with proper grounding and power supply. Or it was a bad piece of electronics. More often then not it is a power/ground situation and can be solved with a little time.


                            • #15
                              I'm having this same problem too (my thread disappeared somewhere, but whatever). I'd like to avoid using a ground loop isolator, though, since that seems to be a bandaid solution to a bigger problem - I'd like to find the solution for it.

                              Is it a problem that I'm using a headphone jack -> RCA cable? Maybe it's crappy quality? My HU is grounded properly; but maybe my PC is not? If I take a wire and touch it to the car body and then fish around around the ports, I can hear crackling through speakers (though it never really gets rid of the noise).

                              My system is very simple (stock speakers, no amp, non-factory HU and M10000), so I don't think it's a multiple grounding issue and so on.

                              Note: if I switch the HU to CD/Radio, it works fine - only on AUX mode do I get this interference.

                              Anybody know what's up?
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