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massive noise when i plug my laptop in

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  • massive noise when i plug my laptop in

    my system is nice and quiet when my laptop is running on batteries, as soon as i plug the AC adapter into the lighter though, everything goes nuts. it sounds like a helicopter is in my car and the video has lines running through it pulsing to the sound. probably some sort of grounding issue but is there an easy way to troubleshoot/solve?

  • #2
    Maybe you could try another lighter adapter. Also are you sure that the lighter is producing enough power to run the laptop?
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    • #3
      Laptop sound cards ae natorious for horrible integrated sound cards.

      What kind of noise is it? Alternator whine? Static? I am researching the cause of the alternator whine in my system.

      Please post more info
      -Jesus- King of Kings Lord of Lords

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      • #4
        I sometimes get a lot of noise on my laptop due to a bad earth I think but then i do have a solid magnesium case. Try running an extension lead out yo your car and run your laptop with the AC adapter running on mains but still have it playing through your car and see if that helps. Also, check the headphone connection on your laptop.

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        • #5
          ill check all this stuff, but again when its on battery, no problems, quiet as a mouse, so its not a sound card issue. im going to guess on AC power it wont be a problem. its not alternator whine, i cant quite describe it other than a helicopter . ive routed the DC power wire away from all other wires and it quiets it down a little but it's still bad. at some point i'll try to wire it direct to the battery which is how everything else is wired and see how we fare.

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          • #6
            Originally posted by robr
            ill check all this stuff, but again when its on battery, no problems, quiet as a mouse, so its not a sound card issue.
            Not necessarily true. the problem is only apparent when the car is on and there is tons of noise surging through the system. Your sound card can't deal with the noise or surpress it becasue of its tiny circuitry and therfor passes it along out the speakers

            I only hear the alternator whine when the car is on and not on battery. That probably means that there is a wrong ground somwhere but it doesn't make itself apparent until the car is on. You can't discount anything in these scenerios.

            Unless you want to work on grounding the the laptop better you might want to try some sort of noise suppressors
            -Jesus- King of Kings Lord of Lords

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            • #7
              If you wire direct to the battery I think you're problems will be solved. I'm sure it's a grounding issue, but I'm not sure if it's just your lighter adapter or if its the cig lighter itself. That's why you have the helicopter noise that pulses in and out, thats a grounding problem. The reason I think it's also a power issue is because you're getting lines on the screen which ususally means either too much power or too little...most times too little or this could also be related to grounding.
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              • #8
                Originally posted by antimatter
                Not necessarily true. the problem is only apparent when the car is on and there is tons of noise surging through the system. Your sound card can't deal with the noise or surpress it becasue of its tiny circuitry and therfor passes it along out the speakers

                I only hear the alternator whine when the car is on and not on battery. That probably means that there is a wrong ground somwhere but it doesn't make itself apparent until the car is on. You can't discount anything in these scenerios.

                Unless you want to work on grounding the the laptop better you might want to try some sort of noise suppressors

                You may be able to minimize your alty whine with some adjustments to your gains. You are right it is probably a ground issue for you as well, but sometimes having the gains set too high will bring in sound. Are you getting it through all the speakers and woofer? A way you can narrow things down is temporarily hook up a speaker to the head unit. See if the head unit produces whine as well. If not then it's probably the amp ground. Wait do you even use a head unit?
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                • #9
                  Take it from me. Do it right the first time, Wire everything properly and don't skimp.
                  -Jesus- King of Kings Lord of Lords

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                  • #10
                    Well not to hijack this thread...

                    First off no HU. Just the carputer

                    Secondly my system consists of the following componants
                    carputer-->digital coax cable-->surround sound processor-->amp-->speakers

                    I am going to do some more troubleshootiung in about 10mins but from what i can tell the problem is between the Surround Sound Processor and the AMP even though i have 1 foot 25 dollar RCA Pheonix Gold Cables
                    -Jesus- King of Kings Lord of Lords

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                    • #11
                      Originally posted by antimatter
                      Well not to hijack this thread...

                      First off no HU. Just the carputer

                      Secondly my system consists of the following componants
                      carputer-->digital coax cable-->surround sound processor-->amp-->speakers

                      I am going to do some more troubleshootiung in about 10mins but from what i can tell the problem is between the Surround Sound Processor and the AMP even though i have 1 foot 25 dollar RCA Pheonix Gold Cables
                      Man I wish I could help, but I have no experience with digi coax, or a ss proc in the car environment. One question for ya, are you using a common ground for all your equpment?
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                      • #12
                        Bleh. Grounding.

                        Right now, you're powering (and therefore probably grounding) your audio equipment and your source (in this case, carPC) in different places. Unless of course your headunit or amplifier is powered by the cigarette lighter, which is unlikely.

                        You have't told us what other audio equipment you're running, so I don't know how your system works. You didn't mention whether the noise happens both when the engine is on and off, so I'll assume that it's all nice when the motor is off.

                        Suffice it to say that the first, and biggest trick to eliminating noise is grounding everything at exactly the same place. This doesn't need to be at the battery - in fact the shortest ground connection is the best. By minimising the ground difference potential, you're helping stop those nasty noises.

                        Have a look at the sectioned headed Engine Noise on this page: http://www.bcae1.com/audiots.htm

                        C!
                        http://carpc.riposte.net
                        I reserve all rights in connection to each post I author, without exception.

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                        • #13
                          Originally posted by C4M
                          Bleh. Grounding.

                          Right now, you're powering (and therefore probably grounding) your audio equipment and your source (in this case, carPC) in different places. Unless of course your headunit or amplifier is powered by the cigarette lighter, which is unlikely.

                          You have't told us what other audio equipment you're running, so I don't know how your system works. You didn't mention whether the noise happens both when the engine is on and off, so I'll assume that it's all nice when the motor is off.

                          Suffice it to say that the first, and biggest trick to eliminating noise is grounding everything at exactly the same place. This doesn't need to be at the battery - in fact the shortest ground connection is the best. By minimising the ground difference potential, you're helping stop those nasty noises.

                          Have a look at the sectioned headed Engine Noise on this page: http://www.bcae1.com/audiots.htm

                          C!
                          When using the cig lighter you can't use common ground because you're sticking it in the cig lighter. Also I'm not completely sold on common ground. I think like equipment should be grounded in the same place, but not all equipment. This is just from my experience though and not something that I have extensive facts to back up. I just know if I took my experiences as test cases then amps having common grounds are ok, aslo elec cross'rs, but I wouldn't ground a car pc with my amps just because of the sheer amount of current that goes through amps. Basically a rule of thumb I use is big power can ground with big power, small power can ground with small power, and anything that is known to induce noise or have problems with inducing noise shoule be grounded alone and a nice distance from any other grounds.
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                          • #14
                            Hello. Last night I tore apart my whole system with some good information handy (many hours of googleing). This what I did to cure my noise. I tracked the the noise back to 3 main causes.

                            1 helecopter sounding noise: (while testing i used some of the factory wiring for my + lead for the computer) this with an analog line (not digital though i have both) i found that my lack of grounding from the motherboard to the power supply etc etc was causing some of the noise. That and when i used a clean (direct to the battery) connection with the + lead that goes to the computer that it eliminated all of the noise but the engine hum that changes with engine RPM's.

                            Engine Hum (alternator whine): So after forcing myself to ground the computer to a common ground (with the positive lead going to the battery) I think I eliminated part of the hum. Star grounding works. I may relocate my ground to a more central location but that is to be determined at a later time

                            Also to cure the alternator whine I properly tuned my amp and DSP. What had happened is that I originally had the amp turned down all of the way producing very little sound and the DSP's gain was maxed out. With the individual gain on each chanel put to +12db (the max) i got the engine whine no matter what i did. So i turned the channel volume down on the DSP and properly set the amps channel volume to a higher level to compensate.

                            Other things that I did that possibly helped:
                            My digital coax line running from the computer and my analog RCA's (paid 75 bucks for the RCA's) were both crossing tons of wiring within my glovebox (where computer is mounted) so i seperated the audio cable to as far away as possible that i could move them.

                            All of these things helped but the one thing that was the main cause of my noise (since i am mainly using the digital line back to the surround sound processor and not the analog) was properly tuning my amp and surround sound processor.

                            At this time i should add how much sound the D'artigan 5.1 amp kicks out so much sound. I blew my other front speaker hahaha, now i have more excuse to get rid of the stock crap that I have.

                            Thanks for all of your help
                            -Jesus- King of Kings Lord of Lords

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                            • #15
                              @antimatter

                              That's great man, I'm glad you got things running properly...now go get you some new speakers soldier.
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