The mysteries of the J1 header and front panels

twistedemotions

[color=black]I’ll start off this topic by saying I love to tinker with things and can be a perfectionist. If you don’t share these interests, and have no taste for modding, then I suggest avoiding this discussion.[/color]

[color=black]Let us begin! As many know, a multitude of cases come with front panel I/O connectivity. This includes two front-panel audio jacks. One jack is for headphones, and the other for a microphone. These are almost always built to function with AC97 onboard audio. This unfortunately leaves us owners of Creative Labs cards out in the cold.[/color]

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[color=black]Large OEMs (Dell) have their own cases that feature some sort of front panel audio I/O. For these OEM systems Creative has provided a header on Audigy/X-fi cards. This header is referred to as J1, and provides the ability to connect two analog front-panel ports (headphone and microphone).[/color]

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[color=red]WARNING: The J1 header is not to be confused with the header used for the X-Fi/Audigy Drive. This header is referred to as AD_EXT. The AD_EXT inputs and outputs use digital signals (J1 uses analog). While it is possible to put together something using this, it would require building a converter. That’s another topic and beyond the level of my expertise.[/color]



[color=black]Unfortunately Creative is tight fisted with this information unless you are a large OEM. This is because:[/color]

[color=black]A) Creative would like you to buy a more expensive model, with a X-Fi Drive, if you need front panel connectivity.[/color]

[color=black]B) Creative doesn’t want to deal with returns for those who damage their cards.[/color]

[color=black]To further discourage individuals from messing with the J1 header Creative uses a smaller type of pins than is typically used in PCs.[/color]


[color=black]Anyways, lets start with information on the passive AC97 front-panel dongles that come with most cases. These are expected to be used with the onboard AC97 audio on your motherboard.[/color]

[color=black]Here is your typical NC (Normally Closed), switching type, 3 conductor (ring-tip-sleeve) mini-phone jack. This is the type of jack used on most front panels:[/color]
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[color=black]The connection to the sleeve is the rectangle on the left. The upper line with the notch is the connection to the ring, and the lower line with the notch is the connection to the tip. The jack also has two normally closed switches that connect to the contacts themselves. Wiring connections are illustrated with white circles.[/color]

[color=black]In a typical front panel setup, two of these are soldered onto a PCB with a header. Wires attached to this header are then run to the appropriate connections on your motherboards on-board audio.[/color]

[color=black]Now lets look at how an AC97 front panel headphone jack works:[/color]
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[color=black]As you can see the switches in the jack are normally closed... So the signal passes from your motherboard, up the wire, into the headphone jack, back through the wire, into your motherboard. When a jack is plugged in, the switches are open, breaking the signal back to your motherboard.[/color]

[color=black]Now... I have to mention some ugliness. Some case manufacturers (*cough* Coolermaster, *cough* Silverstone) do something like this on the wires that connect to the motherboard:[/color]
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[color=black]This will result in your backpanel outputs (in other words, your speakers) continuing to receive a signal while you have headphones hooked up. Note that sometimes this is also accomplished with some trickery on the front panel dongle PCB.[/color]

[color=black]Here is how an AC97 microphone jack is expected to be wired:[/color]
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[color=black]I haven't looked into the details of the microphone jack as much, but this is what you will see.[/color]

[color=black]Next I will go into Creatives J1 header but.... I'm afraid I will have to continue this post later. I need some sleep. [/color]

[color=black]TO BE CONTINUED[/color]

twistedemotions

Here is the confirmed pin-out for the J1 header:

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Note this is how the header is mounted on the card:

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Pin 3, the headphone detection pin, is of particular interest. When this is switched to ground your back-panel connected will mute.



These are the descriptions for the other pins floating around on the net, however I am not able to confirm their accuracy yet:

#5 Back-panel Mute -- short to ground#7 key pin (shouldn't be there)


#9 MIC IN MUTE -- ground when mic isn't plugged in, +12VDC when mic is plugged in
#10 Audio cable detect -- will be ground when headphones are plugged in

Pin 3 mutes all the speakers from my tests, and grounding pin 5 appears to do nothing... not even mute the back microphone.


Pin 9 doesn't appear to mute the microphone either. I am thinking if this pin gives 12V when the microphone is plugged in, that it is intended for optional analog circuits present on some panels (Microphone volume for instance). The AC97 spec provides a 5V pin for this, although no one seems to use it. I don't have the equipment handy on me to investigate further.

Now... if you read my previous post, you should see connecting the signal returns on your AC97 front-panel headphone jack to the headphone detection pin (#3) is a useless exercise. This pin is expecting to be grounded when the headphones are present.

Essentially for the headphones Creative is requiring OEM's use this sort of jack:

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This jack has a switch which is normally open. When a plug is inserted the switch closes. This kind of jack is purchasable from Foxconn and is present on the rare Intel HD Audio front panel dongles.... so they are available. (Intel HD Audio front panels are a whole different discussion, and have no direct relation to the J1 header.)

Onto a few other things....There was some talk of the microphone front-panel jack being mute without something in the back-panel mic jack. I however found the microphone front-panel jack did work, however the signal sounded a bit poorer. I did not investigate further. Even if AC97 front-panel dongles are of limited use with the J1 header, I and others could build our own.

I provide this information hoping someone can continue this investigation, and test/document the purpose of pins 5, 7, 9, 10. Of particular interest would be to study a Dell system with a Sound Blaster and functional OEM front-panel ports.

Here are some other links of interest:

http://audigy2zshowto.blogspot.com/
http://structuretoobig.com/home/blogall.aspx?bid=46
http://www.devhardware.com/forums/t15584/s.html
http://www.devhardware.com/forums/sh...4&page=1&pp=15

Trinity

COOLS!!!! Thank you very much. This is the answer for my case: Audigy 1 and Abit Media XP pro Front panel with headphone and mic jack. Soon I'll try and post details.

Trinity

Unfonately my Audigy DE (1) do not have a White jack!!!. I 've checked with some creative soundcard pic and found that even Live24 or Audigy LS still have it (J1). A2 value, A4 value are also have it but mine is not. Do you know how to do with my Audigy? Does anyone know what is function of J7 (3 pin) on A1?

berserkchaos

poor english
it works... but for some reason ther backpanel works even if i short 1-3.

help...

Audigy 2 Dell OEM
YouP-PAX 1.02, Audigy 4 Softmod

dj_stick

some cards in the same series have it, some don't - it's kind of hard to predict

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