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Thread: One solution for alternator whine.

  1. #1
    Join Date
    Mar 2005

    One solution for alternator whine.

    Have finally fixed my alternator whine.

    Just a bit of background - IBM T30 laptop running with Clarion DXZ946MP headunit.

    Headunit has dual zone - so output of headunit runs in through headphone jack to computer and computer's sound card mixes CoPilot wiamp etc with external signal and fed back into auxillary in in head unit - which plays the auxillary in signal on the car speakers (I'm glad my headunit had dual zone!)

    Anyway, when I powered the laptop with a DC-DC adapter running of the cigarette lighter I would get:

    1) a whine related to the engine revving
    2) the sound of the hard disk reading etc

    coming through to the speakers.

    Interestingly without the laptop battery powering the unit there did not seem to be any engine revving noise - and I didn't notice much hard disk reading noise too.

    I tried sperating the wires but it didn't help much.

    Finally, I read on these forums about the external USB soundcard - I got a Griffin imic from ebay - and it works like a charm - no more alternator whine or hard disk. Some people have had trouble using this unless it has a dedicated USB port - buit mine works fine off a USB hub which also has a keyboard and the touch screen plugged in.

    Anyway, am very happy now and hope this helps someone else!

  2. #2
    Newbie rainman6272's Avatar
    Join Date
    Jan 2006
    Oakland, CA
    i'm doing a t30 install with a port replicator and it looks like i'm going to have to get the usb sound too. the hard disk noise is unbearable.

    the noise is there even when i disconnect the power and have the laptop run on it's own batteries, but when i bring it inside and connect the headphone jack on the laptop, no noise! i tried grounding the laptop's chassis directly to the car and that seemed to minimize the hd noise in the video signal, but it didn't do anything for the noise in the speakers. i even tried muting every single source in the mixer panel to no avail. tomorrow i'll try powering the laptop externally (AC) and try playing with some of the amp settings along with trying other sources.

    i really don't want to stick another usb device on there.

  3. #3
    Low Bitrate
    Join Date
    Feb 2005

    RE: External souncard will give better sound

    I have a IBM R51 installed in a docking station and I too had alternator whine. I first ran the speaker wires as far from any power wires as possible. I also grounded the powersupply (Kensington unit wired to distribution block to battery) and the headunit to the same location. These two fixes dramatically reduced the whine, but did not get rid of it.

    However, the internal nature of the soundcard in a laptop makes shielding it from external interference very difficult, not to mention the low quality.

    I installed a Phillips Aurillium USB soundcard and all the noise is gone. Not to mention that the sound is 10x better than the lappie's internal card. It does not sound too bad with headphones, but crank the output, as in a car application, and you can hear the card clipping both the highs and lows.


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