Help! How to get digital audio from mobo?

beaker

I am about to order a pre-built system with a Gigabyte H81M-D2V (product page).

I did a lot of googling but I can't find the answer to this audio question: is there a cable that will take 5.1 digital audio from the motherboard directly to an optical or coaxial digital input on my receiver? The only audio outputs on the motherboard appear to be headphone-jack-type (see bottom right of this image).

Thanks!

Hachiko

that doesn't seem to have an optical output, i am sure you need an additional sound card to get that feature, i have not dabbled with motherboards for years so might be wrong.

Luck100

Nope, it doesn't have optical output. You need a different motherboard.

Luck100

Here are some that have optical output:

http://www.msi.com/product/mb/H97MG43.html#hero-specification

http://www.asus.com/Motherboards/Z97A/specifications/

I've used both and they both work properly in terms of sending 5.1 audio to the AV receiver via the optical connector. The Asus also has a feature that will convert audio from other surround formats to Dolby Digital so it can go to the receiver via optical.

beaker

Thanks for the replies.

Either optical or coaxial would do for my receiver. I am doing lots of googling to try to figure it out. Do I need the motherboard to support SPDIF out? Are the "HD Audio" jacks in the image above capable of SPDIF out?

(Sorry if the above is nonsense - I am trying to wrap my head around how this stuff works. Any help would be much appreciated! )

Luck100

I'm pretty sure the "HD Audio" jacks are analog surround sound outputs. They probably need some special connectors/cabling as they have more than one channel on each jack.

For digital output you need optical or coax spec'd on the motherboard (not HD Audio). Look at those links I posted, you'll see where it says optical SPDIF rear audio ports. Beware that some motherboards SAY they have SPDIF, but it's only an internal header - presumably they require a case that has the external SPDIF port built-in, and a special cable to connect the motherboard header to the port on the case.

I've gone through this at length on my own while I was building an HTPC. Unfortunately not many motherboards have optical SPDIF - probably because most people will use HDMI for digital audio. I needed optical because my receiver (while sounding quite nice) pre-dates HDMI.

Luck100

This is the back panel of the MSI motherboard. The top connector in the group second from the left is optical SPDIF. That's what you need.

beaker

Luck100 wrote: »

Here are some that have optical output:

http://www.msi.com/product/mb/H97MG43.html#hero-specification

http://www.asus.com/Motherboards/Z97A/specifications/

I've used both and they both work properly in terms of sending 5.1 audio to the AV receiver via the optical connector. The Asus also has a feature that will convert audio from other surround formats to Dolby Digital so it can go to the receiver via optical.

(My last post crossed with yours)

Thanks a million for the links and the follow-up post.

Looks like I will have to pay 2 or three times as much for a mobo just to get optical. Is that the way to go or is there any cheaper sound card option, do you think?

Also, I have read some scary comments saying that gaming surround audio is trickier on PC than movie surround audio. Will having optical on the mobo mean that I get all audio in 5.1 through the optical - games and all?

Cheers.

Luck100

Yes, choices are very limited if you require optical audio. I seriously thought about upgrading my receiver so I could just use HDMI, but in the end I went with the Asus board I linked above.

Next thing you should understand is that optical audio can only transport certain types of digital audio streams: stereo PCM (up to 96 KHz I believe), Dolby Digital (DD), and DTS. PCM is uncompressed raw digital audio. DD and DTS are compressed surround sound formats (I only have a 5.1 receiver, but I think they can do 7.1 also - not sure). Movie soundtracks are often encode as DD or DTS, so with proper support from your video playback software you should be able to pass through the DD or DTS surround sound to your receiver, which will decode and play in full surround glory. You will be able to do that with any motherboard that has optical audio output.

Surround sound in games is generally NOT encoded as DD or DTS - they are just raw 5.1 or 7.1 surround channels of uncompressed audio. So they will NOT transfer over the optical audio connector, as it doesn't have the bandwidth to handle uncompressed surround sound. You will either need to use HDMI audio, or you need a motherboard like my Asus which has the DTS connect feature. DTS connect will take 5.1 or 7.1 audio (say from a game) and re-encode it as DTS so that it can pass over the optical audio connector.

beaker

Luck100 wrote: »

Yes, choices are very limited if you require optical audio. I seriously thought about upgrading my receiver so I could just use HDMI, but in the end I went with the Asus board I linked above.

Next thing you should understand is that optical audio can only transport certain types of digital audio streams: stereo PCM (up to 96 KHz I believe), Dolby Digital (DD), and DTS. PCM is uncompressed raw digital audio. DD and DTS are compressed surround sound formats (I only have a 5.1 receiver, but I think they can do 7.1 also - not sure). Movie soundtracks are often encode as DD or DTS, so with proper support from your video playback software you should be able to pass through the DD or DTS surround sound to your receiver, which will decode and play in full surround glory. You will be able to do that with any motherboard that has optical audio output.

Surround sound in games is generally NOT encoded as DD or DTS - they are just raw 5.1 or 7.1 surround channels of uncompressed audio. So they will NOT transfer over the optical audio connector, as it doesn't have the bandwidth to handle uncompressed surround sound. You will either need to use HDMI audio, or you need a motherboard like my Asus which has the DTS connect feature. DTS connect will take 5.1 or 7.1 audio (say from a game) and re-encode it as DTS so that it can pass over the optical audio connector.

Wow. Great explanation. Thanks.

The annoying thing is that I have a decent Onkyo TX-SR606 receiver that does HDMI switching but it has a known issue and the HDMI switching is flaky. So I use HDMI direct from my current PC to my TV for video and optical to my receiver for audio.


So am I correct in understanding that if my receiver was working OK (or I got a new one) then even the cheap (HD Audio) mobo would output uncompressed 5.1 from a game over HDMI to my receiver and my receiver would happily handle it?

Luck100

Well, that motherboard you put in your original post doesn't have any HDMI outputs. All I see is DVI and D-sub. If you go with that motherboard, then you need to also add a separate discrete graphics card with HDMI. Probably better to just get a different motherboard which does have HDMI - which should be easy, almost all of the have it now. Frankly I'm surprised to see one which doesn't have it.

I've never used HDMI audio so there may be some issues that I don't know about. But as far as I understand HDMI will cover all the formats that optical does plus uncompressed surround formats as well (providing your receiver supports them - worth having a check on your receiver's specs).

beaker

Luck100 wrote: »

Well, that motherboard you put in your original post doesn't have any HDMI outputs. All I see is DVI and D-sub. If you go with that motherboard, then you need to also add a separate discrete graphics card with HDMI. Probably better to just get a different motherboard which does have HDMI - which should be easy, almost all of the have it now. Frankly I'm surprised to see one which doesn't have it.

I've never used HDMI audio so there may be some issues that I don't know about. But as far as I understand HDMI will cover all the formats that optical does plus uncompressed surround formats as well (providing your receiver supports them - worth having a check on your receiver's specs).

I've just realised (with your help, thanks) that my last post was arseways!

I have a GTX 970 in the spec and THAT is where the HDMI will be coming from - for video, anyway.

I am trying to picture a setup where the video goes from video card to TV over HDMI and the audio goes from mobo to receiver over a different HDMI cable. I'll have a google around that but it sounds either messy or plain impossible.

Luck100

Glad to help. I really doubt that you will be able to route audio/video over two different HDMI ports, but it's certainly outside my world of experience

beaker

I looked into it and 'audio only' over HDMI is a hack - you need to send dummy video along with it. Sounds like a mess.

Last question! I promise (with my fingers only slightly crossed! ;-) )

I've just spotted that me receiver has:

DVD FRONT L/R, CENTER, SUBWOOFER, SURR L/R, and SURR BACK L/R

This analog multichannel input is for connecting a component with a 5.1/7.1-channel analog audio output, such as a DVD player, DVD-Audio or SACD-capable player, or an MPEG decoder.

Do you think I could use analog cables to connect the cheap HD Audio mobo to my receiver?

See the two attached images.

ED E

You'll only get 2.1 that way.

TBH considering you already have a quality audio setup yo may as well match it at the source, no point putting crude oil into an F1 car. Get an external DAC with the correct outputs.

Luck100

HD Audio on the rear connectors is only stereo, not surround. To get surround, you have to connect the motherboard front panel audio header to a corresponding set of jacks on the front panel of the case - assuming your case even has them. Then you probably need a special set of cables to be able to connect from the computer to the receiver. It's not described terribly well in the manual . All in all not really worth in in my opinion as the audio quality will probably not be great. It's really meant for cheap computer-style surround speakers, not a sound system with a proper amp.

Your cheapest option is to just pay a bit more and get a mobo that has optical audio output on the back panel. The more expensive option is to fix or replace your receiver so you can use HDMI for audio/video and do switching through your receiver as it's meant to be done.

beaker

Thanks for the input.

I have had a look at the motherboard manual and I think I see two potential solutions:

ED E wrote: »

You'll only get 2.1 that way.

It looks to me that I could get 5.1. Have a look at the SurroundConfiguration image below from the mobo manual. The three audio jacks Line In, Line Out and Mic transform into Front, Rear and Centre/Sub. I presume I could use headphone jack to RCA cables to go from motherboard to receiver. Would this give me decent audio quality?

ED E wrote: »

TBH considering you already have a quality audio setup you may as well match it at the source, no point putting crude oil into an F1 car. Get an external DAC with the correct outputs.

I also discovered that the motherboard has an internal SPDIF that can be used if I add a SPDIF Out module (see image attached). That would be better, right? Wouldn't that give me perfect digital out for the the DAC in my Onkyo to handle? That would work for games too, right?

I reckon I am close to having this figured out. Any help that gets me over the line would be great. Thanks!

Luck100

Like I said before, SPDIF will NOT give you surround sound in games unless your motherboard has the DTS Connect feature.

You can get analog 7.1 output using the rear and front audio jack outputs like in the diagram you attached. Quality will depend on the quality of the onboard sound of your motherboard. You'll need four cables with jack connectors on one end a y-split into two rca connectors on the other (for your receiver).