# Gigabyte mobo front audio header



## timk9 (Feb 22, 2006)

Hopefully this topic hasn't already been discussed, I haven't seen one...

I have a Gigabyte GA-8GPNXP-Duo motherboard with a C-Media 9880 Azalia onboard 7.1 HD audio. This onboard audio adapter has a front-panel connector on the motherboard. According to the motherboard manual, the pinout is as follows:

1 MIC2_L
2 GND
3 MIC2_R
4 -ACZ_DET
5 LINE2_R
6 FSENSE1
7 FAUOIO_JD
8 NC
9 LINE2_L
10 FSENSE2

I have a front drive bay panel from Aerocool, which offers a mic, headphone, and lineout jack. I was able to make a cable for the mic and headphone jacks (I can live without the front lineout) but I have no idea what to do with pins 4/6/7/10. I've tried using the front jacks without the sense pins but they're not detected by the driver (duh). Google hasn't turned up anything useful for me. Any ideas?

Thanks!
Tim


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## UncleMacro (Jan 26, 2005)

Those extra pins implement Intel's jack sensing feature which allows them to figure out what is plugged into each jack. This is the pinout and basic descriptions. This PDF has technical info on front panel stuff if you want to delve deeper.


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## timk9 (Feb 22, 2006)

Thanks for the response. I understand the purpose of the sense pins but I don't know what I should do with them. My Aerocool panel is clearly not a standard Intel front audio panel, and here is its pinout diagram. It has L/R/GND mic, l/r/gnd lineout, and l/r/gnd linein. I believe the board header only has l/r mic and l/r lineout (I can do without the other). I connected the mic and lineout wires and verified with a multimeter but the jacks don't function and aren't recognized by the driver.

I obviously need to connect something to the sense pins but I don't know what. Do any pins need to be jumped? Thanks for the links. I'm glad to see that my pinout is the standard Intel HD Audio spec (one other pinout on my board is not standard). I will read the white paper but that will take some time, I'm hoping you have a simple solution.

Thanks again!
Tim


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## UncleMacro (Jan 26, 2005)

Unfortunately, GigaByte doesn't have your motherboard manual available for download so I'm just guessing here... Your case is using the old AC'97 front panel and your motherboard uses the new HD audio. On most motherboards, you can connect an AC'97 front panel to an HD audio connector but you lose the jack sensing feature. That's why the "main" pins haven't moved from AC'97 to HD audio. It's to allow backward compatibility to older AC'97 front panels.

If your motherboard can accept both kind of front panels then there will be a BIOS switch which tells the motherboard which kind is connected. You'll have to tell your BIOS that you have an AC'97 connected. You may have to dig around a bit to find it. Sometimes the option refers to the audio controller name like Azalia for the CMedia 9880 instead of something obvious like "AC'97" or "hi def audio".


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## timk9 (Feb 22, 2006)

Well I did some research and it seems that my front panel is neither HD audio nor AC97 compliant. It simply has wires for L/R/GND, with a proprietary pinout and no sense function. It was actually designed to use pass-through cables to plug in to rear jacks. I don't like that, I want to use the motherboard headers, so I made a cable. I don't really need dynamic jack retasking, I just want simple front headphones/mic. I don't even want it to disable the rear jacks, which seems to be the purpose of the sense wire.

After reading a diagram on www.frontx.com I got the idea to Y-split the wire from signal pin6 to sense pin5, and from 10-9, leaving the two JD pins empty. (See this and this but they're not the same panel I use.) I assume this would duplicate the signal onto the sense pin, thus not disabling the rear port. Am I understanding correctly? The physical jacks on the panel don't have the capability to toggle a signal based on plugged-in status like the paper you sent me or the frontx diagram above.

Thanks again!
Tim


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## UncleMacro (Jan 26, 2005)

After spending a bit more time reading Intel's spec:

Pin 4 is used to tell the motherboard whether an HD front panel is connected. An HD front panel connects pin 4 to ground whereas a standard AC'97 front panels ignores pin 4. So if you connect pin 4 to ground, the motherboard should assume that you have an HD front panel. If you leave pin 4 disconnected, then it should assume you have an AC'97 front panel. The BIOS option provided by some motherboards is probably a way of ignoring pin 4 and just manually telling the motherboard which kind of front panel is connected. The BIOS option would be useful for AC'97ish front panels which don't ignore pin 4 and assume that it's connected to AUD_GND. At least, that's what I think Intel's doing. AC'97 front panels don't always look like the one in their spec.

When you plug something into an HD front panel headphone jack, the switching jack connects pins 7 and 10. When nothing is plugged in, pins 7 and 10 are not connected. That's how the sensing works. It's just a switch which connects 7 and 10 when something is plugged in. The other front panel jack (the mic) connects 6 and 10 when something is plugged in. HD front panels never connect pins 6, 7, or 10 to an audio signal.

In an AC'97 front panel, pin 9 is the left lineout and pin 10 connects to the back panel lineout jack. The switching jack just connects pin 9 to pin 10 whenever nothing is plugged into the front panel so the sound appears at the back panel. When you plug something into the front panel, the switching jack connects pin 9 to the front jack and leaves pin 10 disconnected. That routes the audio to the front jack and shuts the sound off in back. Basically, it's just a single pole double throw switch which connects pin 9 to either the front or rear jack depending on whether something is plugged into the front. It's simple and effective.

So... first you need to convince your motherboard that you have an AC'97 front panel. It looks like that should happen simply by connecting nothing to pin 4. But if you have a BIOS option which tells the motherboard you have an AC'97 front panel, then you should set it to AC'97 to make sure the motherboard gets it. Now that it thinks you have an AC'97 front panel, you can connect 9, 10, and the front panel jack left channel together. Then connect 5, 6, and the right jack channel together. Then you'll hear the lineout on your front panel without disabling the back panel jack. But that will only work if you set it up as an AC'97 front panel. It won't work if the motherboard thinks you have an HD front panel.


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