AC97 to Intel HD Front Panel (Azalia) Adapter
Recently I've bought a new sound card which is capable of encoding Dolby Digital in realtime through the optical output. I've decided to go for the Creative X-Fi Titanium PCI Express. After reserving an interrupt for the PCI-Express slot in the BIOS I've finally managed to install drivers under WinXP. Plugging the headphones in I run into the next problem. The headphone plugs on the front panel doesn't work anymore. After a short search I've found the reason for it. Intel has released a new connector standard for front panels called Intel® High Definition Front Panel Audio (also called Azalia). This pinout is now used by all new soundcards. The bad thing is that this new connector is said to be pin compatible and they even have the same missing pin. But in fact they are not compatible.
AC97 loops the headphone signal through the front panel before it goes to the rear connector. If you connect a headphone to the front panel this loop is opened. This simple wiring has the only disadvantage that the signal goes through the whole PC case if you connect speakers at the rear jack.
In the new Azalia standard the front and rear jacks are not connected in series but in parallel. The soundcard must either provide an additional output or a switching mechanism. Additional signal lines for jack detection notifies the soundcard when headphones are connected. How the jack detection is treated will certainly depend on the soundcard and it's driver. In my case the X-Fi Titanium turns off any output to the front panel if the jack detection is left open.
If you need only the jack at the front panel you can solve this issue by soldering a simple adapter. This adapter will loop through headphone and microphone channels and shorting the jack detection pins. This adapter is put in between the AC97 front panel cable and the Azalia connector on the soundcard. Doing so, the soundcard alway sees headphones connected to the front panel and will activate this channels. In my case the optical output at the rear panel is still functioning which is all I need.
Since all the audio pins are at the same position I've decided to solder a male and female connector together directly.
I've pulled out all pins except of the audio channels from the male connector. You can see the remaining pins in the following picture. 2 pins for both headphone channels, 2 pins for the mic and 1 pin ground. Before soldering both connectors together I've soldered a small wire to connect pin 7 and pin 10 at the female connector. To solder the connectors the single pin in the upper row of the male connector has to be bend a bit.
That's all. Plugging it onto the Azilia connector on the soundcard and then connecting the AC97 cable of my front panel solves the compatibility issue.