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Thread: Want to use Intel HD Audio Header for Line In and Line Out, Any Suggestions?

  1. #1
    Maximum Bitrate rray's Avatar
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    Want to use Intel HD Audio Header for Line In and Line Out, Any Suggestions?

    I have an Intel DN2800MT board with a dual configuration front panel audio header. I want to use this header to bring Left and Right audio from my HD Radio in, because I mounted my HD Radio board to the case lid, centering it inside the double din case:


    I also mounted RCA jacks to the back panel of the DDIN case, and want to connect them to this header to get L and R Line Out to my car's amp.

    The question is how do I connect everything correctly so the HD Audiio configuration is used.
    I suspect I should use, however I am not sure about Line Out RCA Grounds, or the HD Radio Line In :
    Pin 1 Left HD Radio Audio In
    Pin 2 Ground HD Radio Audio
    Pin 3 Right HD Radio Audio In
    Pin 4 ?????
    Pin 5 Right Line Out to RCA Jack
    Pin 6 Right Line Out Return (RCA Jack gnd)
    Pin 7 ?????
    Pin 8 Key
    Pin 9 Left Line Out to RCA Jack
    Pin 10 Left Line Out Return (RCA Jack gnd)

    Here is the header:



    And here is what the motherboard documentation says about this header's HD Audio or AC97 Configuration

    For HD Audio front panel modules:
    Pin Signal Description
    1 PORT 1L Analog Port 1 - left channel (Microphone)
    2 GND Ground
    3 PORT 1R Analog Port 1 - right channel (Microphone)
    4 PRESENCE# Active low signal that signals BIOS that an Intel® HD Audio dongle is connected to the analog header. PRESENCE# = 0 when an Intel® HD Audio dongle is connected.
    5 PORT 2R Analog Port 2 - right channel (Headphone)
    6 SENSE1_RETURN Jack detection return for front panel (JACK1)
    7 SENSE_SEND Jack detection sense line from the Intel® HD Audio CODEC jack detection resistor network.
    8 KEY No pin
    9 PORT 2L Analog Port 2 - left channel (Headphone)
    10 SENSE2_RETURN Jack detection return for front panel (JACK2)

    For AC97 front panel modules:
    Pin Signal Description Pin Signal Description
    1 MIC Front panel microphone input signal (biased when supporting stereo microphone)
    2 AUD_GND Ground used by analog
    3 MIC_BIAS Microphone power / additional MIC input for stereo microphone support.
    4 AUD_GND Ground used by analog audio circuits
    5 FP_OUT_R Right channel audio signal to front panel (headphone drive capable)
    6 FP_RETURN_R Right channel audio signal return from front panel (when headphones unplugged)
    7 AUD_5V Filtered +5 V used by analog audio circuits.
    8 KEY No pin
    9 FP_OUT_L Left channel audio signal to front panel (headphone drive capable)
    10 FP_RETURN_L Left channel audio signal return from front panel (when headphones unplugged)


    As you can see when I enable AC97, the Line Out (headphone out) is satisfied, but Right Line In becomes Mic Bias, whatever that is.
    And when I enable HD Audio the HD Radio Line In (Mic Left, Gnd, and Mic Right) are satisfied, however what to I use for Line Out L and R Gnd? There is also all this "Presence", "Sense and Sense Return" Jack Resistor Network stuff.

    Can anyone offer up a tried and true method for using this header?

    Thanks,
    Robert

  2. #2
    MySQL Error soundman98's Avatar
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    i think it might be best to use a cable like this to break out the connector, and then make the necessary connections:
    http://www.moddiy.com/products/USB%7...g#.UJinUsU81i0

  3. #3
    Maximum Bitrate rray's Avatar
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    Yes I seen that cable on ebay, and figured if nobody had an answer here, I would get one to reverse engineer. I searched the web high and low and cannot find info on that front panel circuit at all.

    I don't want to mount the jacks and board inside my case, rather create a small circuit to be enveloped in heat shrink tubing between the motherboard header an cables to RCA jacks.

    Thanks for replying Soundman.

    -Robert

  4. #4
    Maximum Bitrate rray's Avatar
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    I spent a couple days researching this issue, and although I am not 100% sure, I came up with wiring diagrams based off the front panel wiring I found online. I am posting here and hope someone with more computer experience than me can approve OR REJECT if known not to work this way.

    Here is my proposed header wiring for both AC97 and HD Audio Line In and Line Out using the front panel header:


    Here is what they want for AC 97 Compliant front panels:



    Here is what they want for Intel HD Audio Compliant front panels:
    Last edited by rray; 11-07-2012 at 07:25 PM.

  5. #5
    Maximum Bitrate rray's Avatar
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    Just to update on this, I only have header pins 1, 2, and 3 connected to Left, Gnd, and Right line level out from the HD Radio receiver now, and use a USB DAC (ObjectiveDAC) for audio out, as it uses a much higher quality DAC than the motherboard provides.

    As it turns out, you can connect to an AC97 or HD Audio header configuration as desired, and just use software to select and configure "Recording" devices for Line In, and "Playback" devices for Line Out. The trick is to go into sound settings, select the recording tab, then right click in the box and check both the "Show Disabled Devices" and "Show Disconnected Devices", then highlight, and select the properties box. From there go to the "Listen" tab and check "Listen to this device", and whatever the microphone or line in records, gets played back on the default audio device. You can also select the "Levels" tab to set the Line In gain, and be sure to check out the other tabs to set things like sample rate, dc offset cancelation to get rid of some kinds of hum, and immediate mode.

    For playback the same thing applies, as there are all kinds of settings for sound quality, etc.

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