Electronics Abit IT7 Audio Header

Can anyone help me figure out what ground pin I have to use on my Abit IT7 for the speaker signal.

Here's the pinout:


It's either pin 2 or pin 11.

I send a mail to Abit, but as expected they haven't answered, I've send the mail 3 days ago .

Could anyone help my find which pin to use, because:

• I don't want to blow up my mobo
• I haven't got acces to the mobo untill wednesday
• I want to finish the solder work by wednesday

 

Oh, and another question: Mic Bias means Mic ground right? Or is it a 2nd mic channel or something?

 

GND = ground. What do u mean by speaker signal ?

edit : lol missed the first bit yer u can use either

 

You can use either. Both are the same.

I don't think mic bias is the ground for the microphone.

 

wouldnt u use the speaker out left channel return as ground for the speaker out left signal? it sort of makes sense as the pins are next to each other

 

No eaterofpies, normaly there's a jumper from left -> left_return and that goes to the audio output at the back, so when you connect something else to it, your audio outputs at the back go out -> boxes go out.

And what should I use as ground for the mic then?
Are you guys absolutely sure that I can use either ground, because I don't want to **** up my mobo .

 

Yes I'm quite certain you can use either ground, seems to me though that it would make sense to use the GND next to the mic pin as the ground for the mic, and the GND on pin 11 for the speakers. They should be the same however.

 

Ok, so I'll use the pin I want .

But what's Mic Bias?

 

Sorry to bump this, but I figured it might be useful to know:
Mic bias is the microphone power power.

I found it here (p20): http://www.formfactors.org/developer/fpio_design_guideline.pdf

And you connect it like this:
"The microphone inputs (mono) connect to a 1/8-inch ring-tip-sleeve mini-phone jack (= simple 3.5mm mono audio jack) mounted on the front pannel. The tip provides the Microphone In signal, and the ring provides the Audio Microphone Bias signal."

So you just connect the Audio Mic pin to the audio connection on the jack (or the left channel if you're using a stereo jack, like I did) and connect the Mic Bias pin to the ground of the audio jack.

Oh, and for those you're wondering if the switching thing works, well, it works, but the mobo doensn't disable the satelite/center/subwoofer speakers when there's no left/right audio signal, so when I connect my 5.1 system to the mobo and I plug in a headphone I can still hear music coming out of my boxes . Oh well, I'm going to use it untill I can create a better circuit, it's still usefull at a LAN .

 

Devil, you misinterpreted that statement, as microphones have this pinout, from tip to sleeve: signal, +5v, ground. Mic Bias sounds like +5v, as there's already two ground connections there.

 

Well, then I think I'm correct.
I'm thinking like this:
- boxes: output things: output @ mobo -> boxes -> ground
- mic: inputs things: +v @ mobo -> mic -> signal in @ mobo

Wouldn't that be correct? I don't see any way the mic would get power otherwise. With boxes the power comes from the signal, but mic's send a signal, they don't receive one, so I think they need some kind of +v.

 

Ok, finally I found it.
After testing yesterday it became clear to me that I'd need 3 connections: ground, +v & signal.
And I was correct, wohoo .


+5v = Mic Bias

FYI: http://www.hut.fi/Misc/Electronics/circuits/microphone_powering.html