I think I can provide a tl;dr question here: If I have Ear L 1, Ear R 1, Ear L 2, and Ear R 2 connectors, can I presume the 1's are the main Line outs, while the 2's are the return / bline / whatever-else-people-may-call it? If so, on what pins?

Secondary question: I have a missing connector among the Mic ones; is it GND? I don't mind not connecting Mic if it' risky.

Full details

Upgrading hardware and using the old to make a "new" old computer. I have a case I got from a friend whose front panel audio connectors are divided into two cables:

  • Cable 1: Mic-VCC (red), Mic GND (black), unknown (white; connector missing) -[what's missing? Should I leave mic disconncted?]
  • Cable 2: Ear L 1 (black), Ear R 1 (brown), GND (black), Ear L 2 (red), Ear R 2 (orange).

My motherboard is a Gigabyte GA-MA785GM-US2H, whose header supports both AC '97 and HD audio. Details should be here, though website is down right now, but I guess it was always best to reproduce here what the manual says anyway:

HD Audio

  1. MIC2_L
  2. GND
  3. MIC2_R
  4. -ACZ_DET
  5. Line2_R
  6. GND
  7. Faudio_JD
  8. no pin
  9. Line2_L
  10. GND

AC '97

  1. Mic
  2. GND
  3. Mic Pwr
  4. NC
  5. Line out R
  6. NC
  7. NC
  8. No pin
  9. Line out L
  10. NC

Now, from my research and a helpful response on this topic, I think I kind of get what's going on, as there are apparently many ways that these audio cables can be labeled, so I should be able to follow instructions like those in that topic and just substitute my weird 2's connectors with the varying ones I read about online. However, I don't know exactly what pins. If they're going in to the 5 & 6 and 9 & 10 pins, which takes Ear 1 and which takes Ear 2?

Does being this concerned even matter? As long as VCC and GNDs are matched or left alone correctly, and maybe output vs input is correct, is there any risk of ruining anything if mismatched?


  • Which codec do you have in the first place? If you are using Linux, cat /proc/asound/card*/codec\#* will produce detailed information about the I/O pins for an Intel HD codec, while cat /proc/asound/card*/codec97\#0/ac97\#0-0 will give you information about an AC97 codec. Headpiece (HP) out which would correspond to Ear, and Line out are not necessarily identical (possibly different impedance?). – dirkt Dec 21 '16 at 18:39
  • @dirkt, haven't heard "codec" used in this situation. If you're asking what's on the motherboard, I said in my post that the board supports both, and that means on the same header. If you really are asking about software matter, then we'd have to wait until I finish putting this thing together and use a LiveCD (haven't decide this PC's OS), but I would have the impression that software doesn't matter at this point; If my outputs want HD audio and I hook it up on my header as HD audio, I figure I'd just set up my audio that way in the OS. – Rhoi Dec 21 '16 at 23:04
  • The chip that actually does the D/A conversion, routing etc. is called codec. There are several standards, among them AC97 and [Intel HD]( en.wikipedia.org/wiki/Intel_High_Definition_Audio). Just because the motherboard supports both doesn't mean the actually codec chip you have supports both. If you got a switchable chip (that supports both standards), then you need to switch it to whatever connection you make. There are (small) differences (biased mic/stereo mic, sensing), so look closely. – dirkt Dec 22 '16 at 10:38

Your Answer

By clicking "Post Your Answer", you acknowledge that you have read our updated terms of service, privacy policy and cookie policy, and that your continued use of the website is subject to these policies.

Browse other questions tagged or ask your own question.