Spdif In - Nf7s

[DDogg]

Hope all of you are doing well.

Attempted to get an answer from many forums to no avail. Thought I would come home and ask the question where the serious audio people are.

The question is simply has anybody got first hand experience with using the SPDIF IN header on the [Abit] NF7S V2 successfully? I can't get it to work, so I am pausing my efforts until somebody verifies that it does indeed work correctly. If so, I'll take the time to figure out what the problem is on my rig.

[Emp3r0r]

Did your board come with an input or did you roll your own input? optical or coax?

[DDogg]

I used a panel mount RCA jack to attach to the header on the motherboard as shown here (http://www.motherboardfaqs.com/content.php?content.11). I then connected SPDIF out on a DVD player to this jack as a test signal and enabled SPDIF in in the nvidia NVMixer. Nada nothing. Thanks very much for the reply.

/Add: hmm, I was rereading that link and it says to isolate the ground on the jack from the chassis. I did not as I used a normal filler strip to mount the jack (it was the handiest thing). I need to check continuity from the ground pin on the header to chassis ground. I just assumed (yeah) it was common and still expect it to be. Will double check tomorrow and hope I am wrong about it being common.

[Emp3r0r]

Hey good luck and thanks for link, I'm now thinking of adding a coax output to my computer instead of my xbox. ;)

[DDogg]

Still no luck. I am starting to think the spdif IN does not work at all.

[Nick]

Simply connecting a coax plug to the SPDIF header will not work for input. It works fine for output but not input. The voltage swing from most SPDIF output sources is not enough for the digital logic thresholds of the nForce2 chipset and therefore signal amplification is required.

Unless you're pretty confident about doing this, you should stick to buying a dedicated SPDIF daughterboard, which will preamp the signal for you. I can't seem to find one mande by Abit. I have an ASUS one lying about but that is lousy - it actually only centres the input swing around the 2.5V mark, rather than amplifying the actual swing. From my MiniDisc player, that wasn't even enough to register on the board it was designed for :(

I'm currently using an EPoX one.
http://www.epox.org/products/mainboards/spdoc/

but it only offers optical SPDIF in.

Good luck with it anyhow.

Cheers
Nick

[DDogg]

Nick, thanks very much for the reply. I was starting to suspect the signal might not be at the right levels, but had no way of knowing for sure. It is good to have that confirmed so I don't waste any more time on it. Just a play time thing to see how it worked (or didn't).

I may investigate some type of amp down the road if it becomes important. I wouldn't think it would be too hard to build some type of follower circuit to correct the levels, but keeping the edges square might be hard to do as I have limited digital circuit experience, and what I did have was 20 years ago.

Thanks again, you are always a gentleman.

[Nick]

Digital circuitry is a bit out of my league but a friend I was speaking to in the bar last night said

"He wants to try an ultra high slew op-amp IC such as a Texas Instruments OPA 354"

If that means any more to you than it did to me, go for your life! :D