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Thread: massive noise when i plug my laptop in

  1. #11
    Maximum Bitrate falconey's Avatar
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    Quote 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?

  2. #12
    C4M
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    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!
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  3. #13
    Maximum Bitrate falconey's Avatar
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    Quote 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.

  4. #14
    Jesus Freak antimatter's Avatar
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    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

  5. #15
    Maximum Bitrate falconey's Avatar
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    @antimatter

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

  6. #16
    Jesus Freak antimatter's Avatar
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    I think car will fit 5x7"s or 6x8"s depending on how the manufacturer measures their speakers.

    Any recomendations?
    -Jesus- King of Kings Lord of Lords

  7. #17
    Maximum Bitrate falconey's Avatar
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    Quote Originally Posted by antimatter
    I think car will fit 5x7"s or 6x8"s depending on how the manufacturer measures their speakers.

    Any recomendations?

    I'd say go to crutchfield.com and check out speakers that will be direct drop in's for your car. Otherwise you'd have to do modifications to get the speakers to fit. For example some speakers are classified as 5 1/4's but have extra metals or baffling that make them bigger while others are just 5 1/4 and that's it. Usually OEM speakers holes are bigger than the actual speaker. So go to crutchfield pick either some components or coax's and read reviews then once you have a few to choose from report back for suggestions. Unless of course you don't mind doing modding to get the speakers in.

  8. #18
    Jesus Freak antimatter's Avatar
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    Good advice. Crutchfield is good... but before i get the speakers i must get rid of this whine once and for all. It seems during lunch time must have moved something but the friggen alternator whine is back.

    More troubleshooting tonight. The onlything i did different was redo the ground connections. Something must not be connected good. I'll keep yall posted.
    -Jesus- King of Kings Lord of Lords

  9. #19
    Jesus Freak antimatter's Avatar
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    Well i am sorry to report no progress has been made. I still can't isolate this friggen alternator whine. I can minimize it but i cant eliminate it. It is always there when the 6 output channels of the DSP are plugged into the 6 inputs on amp even if the DSP has no inputs attached making me think that the whine isn't coming from the computer. Also to corraborate that i plugged in my GF's MP3 player into the same RCA's to test if noise was being picked up throught the RCA (although i couldn't test the Digital Coax)

    So this could be a grounding issue but i am really frsuterated with this problem. I guess i just need to take a break from it and come at it after some good prayer.

    Anyways thanks for your continued help and ideas.

    I wonder if the thread started ever fixed their problem. I bet getting a clean power source would work wonders.
    -Jesus- King of Kings Lord of Lords

  10. #20
    Maximum Bitrate falconey's Avatar
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    Quote Originally Posted by antimatter
    Well i am sorry to report no progress has been made. I still can't isolate this friggen alternator whine. I can minimize it but i cant eliminate it. It is always there when the 6 output channels of the DSP are plugged into the 6 inputs on amp even if the DSP has no inputs attached making me think that the whine isn't coming from the computer. Also to corraborate that i plugged in my GF's MP3 player into the same RCA's to test if noise was being picked up throught the RCA (although i couldn't test the Digital Coax)

    So this could be a grounding issue but i am really frsuterated with this problem. I guess i just need to take a break from it and come at it after some good prayer.

    Anyways thanks for your continued help and ideas.

    I wonder if the thread started ever fixed their problem. I bet getting a clean power source would work wonders.
    Yeah I was wondering how robr was making out, he needs to report back. @antimatter...use that same mp3 player or a portable cd player...plug it into the amp inputs. Play it over the speakers and go for a drive. If the whine exists then it's your amp grounds. If it's gone you can work your way back. Plug it into the dsp and so on and so forth....If you get no whine without the computer then it's in the computer somewhere. I don't think it's the computer though. I think it's the amp or the dsp.

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