NF7-S: How to hookup front panel audio header

Discussion in 'Abit' started by *Vanguard*, Dec 30, 2003.

  1. *Vanguard*

    *Vanguard* Guest

    On the Abit NF7-S (I have the version 2.0 mobo), there is a 14-pin header
    with mic and right & left audio (headphone) pins. Pins 5 & 6 are shorted by
    a jumper as are pins 9 & 10 (for the right and left audio channels). This
    header was designed for use with Abit's Media Kit, a bracket with audio,
    USB, and firewire ports that fits into a 5-1/4" drive bay. My case already
    has 2 USB, mic, and headphone ports in its front panel. I had reviewed the
    mobos and decided on this one thinking that I could then hook it up to the
    case's front panel ports.

    The problem is that the front panel headphone jack is a typical 3-conductor
    connector: right, left, and ground/shield. So how do I connect 3 wires to 4
    pins? In another newsgroups, a repondent said that pins 5 & 6 were both hot
    for one audio channel as were pins 9 & 10. I assume there is a reason that
    the header pins are shorted. If pins 5 & 6 were both hot (i.e., the signal
    line for the audio amp) and were both, say, the right channel then there
    would be no reason for the jumper but then there would be no point to using
    2 pins on the header for the same connection, either. If it is a
    differential output which would explain why there are 2 pins for each audio
    channel (rather than just a signal referenced to ground) then there would be
    no way that I could hook it up to the audio jack. The other respondent said
    to hook the audio jack's left conductor to one of the left audio channel
    pins, the right conductor to one of the right channel pins, and the
    ground/shield to the ground pin on the header. Sounds plausible except I'm
    still leery of why there would be 2 pins on the mobo header for each audio
    channel for a total of 4 pins.

    I'm not into audio electronics but if the 2 pins are differential outputs
    from the same audio amplifier then maybe that's to eliminate noise on the
    unshielded wires running from the mobo header to Abit's Media drive bay kit.
    But if the 2 pins were for the differential output of an audio amp, wouldn't
    it damage the amp to have its differential outputs shorted together?

    The case already has a front panel with 2 USB ports, a microphone jack, and
    a headphone jack. So if I could hook it up to the header pins on the Abit
    mobo then I'd be happy. I don't need the 3 formats of card reader slots and
    the IEEE-1394 (firewire) ports on the front that the Abit Media Kit
    provides, especially since their drive bay kit costs $65. I don't have
    anything using firewire. I don't have digital cameras with memory cards,
    and even if later I get a digital camera then the USB connect to do the
    transfer would be sufficient, or even the backside firewire port using
    Abit's bracket is sufficient.

    For now, I can run the case front panel mic jack out through a hole in the
    backside of the case to the mic port on the backpanel. It looks amateurish
    but it should work. But I'd still like to figure out how to connect the
    front panel audio jack to the mobo's header. I can't just also run it out
    the back and to an audio jack on the backpanel because that would usurp one
    of the ports used to connect the 4-speaker plus subwoofer setup, and I don't
    want to use Y adapter cables nor do I want the speaker connection moved to
    the front panel on the case. There are times when playing games or
    listening to music during the night when I don't want to disturb others that
    are sleeping. So I'd like to plug in a headphone and have the speakers cut
    out just like what happens on my stereo system.

    Before you say that I should hookup my computer to my stereo system and use
    its headphone jack to perform the cutout, I don't want to do that. My
    stereo system is in a different room for use with my audio/video
    entertainment center. I would have to run both the computer and A/V center
    off the same surge protector to ensure impedance mismatch doesn't inflict a
    spike differential on the interconnected equipment that would be caused
    using separate surge protectors, and I don't have permission to modify the
    house's wiring to install a whole-home surge arrestor. I want to keep my
    computer separate of my A/V center.

    Abit has not yet responded to my inquiry on how to hook up their header pins
    to the case front panel jacks. But then they have never responded to any
    inquiry sent to them. They don't care about end users and probably figure
    you have to contact your OEM or retail seller but for a DIY (do it yourself)
    custom built box (that you built), that isn't an option.
    *Vanguard*, Dec 30, 2003
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