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PCMCIA digital optical sound card

Discussion in 'Laptops' started by Josh Walrath, May 28, 2004.

  1. Josh Walrath

    Josh Walrath Guest

    Currently I am using a 1 year old laptop to play music to my home theater
    system. When I am running on battery power, I get a perfect signal to the
    receiver. However, when I plug the laptop into the wall I get a low pitch
    hum through all the speakers. I have researched the problem extensively but
    even when the audio cable is far away from any power cable (including all my
    speaker wires to and from the receiver, I still get the hum). I was
    thinking that if I had an optical connection from my laptop to the receiver
    I wouldn't get any feedback. Problem is, does anyone make a PCMCIA
    soundcard with an optical output or perhaps even a digital shielded coaxil
    output? I have read other newsgroups with links for cheaper USB soundcards
    with optical output but they have been dead ends. If anyone has any ideas
    or knows where I could find what I am looking for it would greatly help.

    Josh Walrath, May 28, 2004
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  2. A PC Card (and that is the correct terminology, "PCMCIA" should no
    longer be used) is not the answer.

    What you want is an external USB sound card. That should solve your
    problem. Several firms make them, Creative has several models, from
    about $40 to about $200.
    Barry Watzman, May 28, 2004
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  3. Josh Walrath

    AndrewJ Guest

    There are ring magnets that will stop that hum. They clamp over the
    power cable right before the plug goes into the notebook. I have over
    a dozen video and sound cables that all came with these magets.
    AndrewJ, May 28, 2004
  4. Josh Walrath

    Jernej Guest

    You might look at RMEs Hmaerfall DSP series of cards:
    http://www.rme-audio.com but that might be a bit of an overkill for your

    Yor problem sounds like ground loop that can be solved by disconecting the
    ground conection of notebooks power cable (a lot of people who use notebooks
    for music production do this).
    Jernej, May 28, 2004
  5. They are not magnets, they are ferrite beads, which act like chokes
    (large inductors). They may or may not stop the noise that he is
    seeing, they are primarily effective against HIGH frequency emissions
    rather than aginst what sounds like 60Hz "hum", but it's worth a try.
    Barry Watzman, May 29, 2004
  6. Josh Walrath

    tc Guest

    Hum is usually caused by a ground loop. An opto-isolator would solve this
    but a cheaper solution woud be an isolation transformer on the audio lines.
    Radio Shack used to carry one. Sometimes, just disconnecting the shield lead
    on the laptop audio out will work.
    tc, May 30, 2004
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