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SPDIF from sound card issue.

Last response: in Components
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September 4, 2011 6:04:46 AM

I've posted a similar question before but apparently someone made it no longer exist.

Basically, how do you know that an SPDIF signal coming from a sound card and going to an external DAC is actually working and is an SPDIF signal. The reason I ask is because I am still able to control the sound characteristics from my soundcard, which leads me to believe that it is still doing all of the processing and just using the external receiver/DAC for power.

Can anyone clarify this for me, or am I misinformed about how SPDIF should work?

More about : spdif sound card issue

September 4, 2011 5:32:34 PM

mmm..... before I got any further, tell me which soundcard you have.
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September 5, 2011 1:12:03 AM

codet74 said:
I've posted a similar question before but apparently someone made it no longer exist.

Basically, how do you know that an SPDIF signal coming from a sound card and going to an external DAC is actually working and is an SPDIF signal. The reason I ask is because I am still able to control the sound characteristics from my soundcard, which leads me to believe that it is still doing all of the processing and just using the external receiver/DAC for power.

Can anyone clarify this for me, or am I misinformed about how SPDIF should work?


If you have exclusively a TOSlink or CoAx digital connection from your soundcard to your receiver/DAC the only way you would get any sound is if SPDIF was working. As noted above, please clarify. What type of soundcard are you using and what type of connection from the SC to the receiver/DAC is employed?
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September 5, 2011 1:45:41 AM

Just because you are using digital output does not mean the soundcard still isn't doing processing. Your're still going through the soundcards drivers, and the soundcard will still perform audio enhancements. The only difference is the actual transformation back to an analog signal is handled by the DAC, and not the soundcard.
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September 6, 2011 4:56:38 AM

Sorry for the late reply, I'm using a Xonar DX that I just got, and I got it exclusively for the optical. I'm connecting my receiver to the DX using an optical connection and that's it.

So that's how SPDIF works then? I thought it would just pass the signal along to the receiver, therefore giving you a cleaner signal for audio quality purposes?
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September 6, 2011 9:36:48 AM

just check SPDIF out on the audio panel, and it should be fine.
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September 6, 2011 12:13:38 PM

Quote:
So that's how SPDIF works then? I thought it would just pass the signal along to the receiver, therefore giving you a cleaner signal for audio quality purposes?


It depends. You can pass through a SPDIF signal from the SPDIF input to the SPDIF output, and it will be unchanged, but any audio that comes directly from the PC will have the audio go through the soundcards driver layer first, and any enhancements from the audio control center will be made at that point.
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September 6, 2011 10:02:17 PM

So correct me if I'm wrong, but what you're saying is that an SPDIF signal from the input to the output is the one that is unchanged?

As I understand it, since my signal is from the SPDIF out on the soundcard to the input on the receiver, it will go through processing.

Is there any way I can do something, anything to get that unchanged signal? I probably wouldn't care but I have reason to believe that the soundcard is introducing unwanted interference/distortion to the signal because I get a reasonable amount of hissing coming from the speakers.

I'm very interested in achieving the best, unadultered signal that I can for purposes of audio quality.

Any ideas?
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September 6, 2011 10:07:41 PM

Oh and another thing I was going to say is that the DX's interface only allows for 2,4,6, or 8 audio channels. Well, I have a 3.1 speaker system, so I'm unsure which one to choose. That's just one reason why I just don't want the soundcard to do anything. There are far better options on the receiver that I have for tweaking the sound.
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September 7, 2011 8:30:38 AM

Use the AC3 codec. That will allow you to make a world of changes to the SPDIF out of the Sound Card, and will also let you disable any changes to the Audio Signal if you want it unchanged while using the SPDIF.

As far as the hissing sounds go, they're from bad grounding of equipment. You need to check which of the systems is not grounded properly, from what I feel is that the 3.1 Audio Speakers that you have might have a 2 Pin Power connector, that's one place where you are getting improper grounding.

The hissing could also be caused because of faulty or cheap cooling fans in the case which might add to static inside the cabinet.
Check for current leaks and loose cables.
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September 7, 2011 3:03:39 PM

For a 3.1 setup, I'd just select 5.1. The missing channels simply won't be played. You can also disable the missing side/rear speakers from a default 5.1 config from within the Windows audio setup.

As for SPDIF giving a clean signal, that depends entirely on the source audio. The only thing digital transmission promises is that now NEW distortions will be created during the transmission. But if the source is low quality, or the speakers/receivers DAC isn't high quality, you can still get a very noisey signal. Its very unlikey that the DX is itself adding distortions during its audio processing.
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September 7, 2011 6:47:34 PM

Ok, that makes alot more sense. I've done more research into the AC3 codec, and that sounds like what I want for this. I have just two more quick questions if everyone can stick with me. :D 

First, by having a low quality source, would that refer to the source of the file being played, such as an MP3 or lossy codec vs a FLAC file or other lossless codec?

Also, I believe that the DX has either a 2 or a 4 pin connector to it for power. Is this what is meant by a 2 pin power connector causing improper grounding? If so, how can I solve that, or maybe I could just get a good reference point of where to start?

Again, I really appreciate all of the replys, because I can't seem to get anyone else on other forums to answer this question. :( 
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September 7, 2011 6:54:51 PM

First:
Yes, low quality source does mean a bad or low quality encode as being the source in any format.

Secondly Yes & No
No the 2 or 4 pin connector is not where the grounding problem may occur.
It generally means that your whole system needs to be properly grounded. All the stuff is connected to the PSU and so finally the PSU should be well grounded too.
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September 7, 2011 8:08:28 PM

Quote:
Again, I really appreciate all of the replys, because I can't seem to get anyone else on other forums to answer this question.


Because most people are clueless about PC audio. Only other place I know where people know their stuff is over at guru3d [ROBSCIX].
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September 7, 2011 8:10:43 PM

And there is an audiophile site too.... :) 
Where Everything starting from PC audio to Monolith speakers are discussed and experimented with....:) 
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September 7, 2011 9:27:27 PM

Alright then, I suppose that's all I need to know for now. I'm going to use the AC3 codec as soon as I have the time, and I'll do more research into grounding components so that I can hopefully eliminate some of the hissing from the speakers.

Thanks yet again for everyone's reply, it's allowed me to actually move forward with this question.
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September 8, 2011 12:13:50 PM

^^ NP. THG actually is starting to get a few people who know what they're talking about. If you still have problems, you could always try and hook up ROBSCIX over at guru3d, as he definatly knows what he's talking about.

Just remember that AC3 is more or less a very low quality codec by todays standards, mainly because its been compressed to such a significant degree. Its only saving grace as a codec is the fact its one of two major formats [DTS being the other] that can carry multi-channel audio over SPDIF. Thats fine if you need to use SPDIF, but thats the parimay reason I always use analog hookups whenever I can.

In any case, the DX is fully capable of encoding to AC3 in realtime [set to 6 channel mode, enable Dolby Digital Live (and Pro Logic if you want to upmix 2.1 audio to 5.1)], so you should have no problems on that front.
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September 8, 2011 5:20:15 PM

Yeah that's that the DX is set for, partly because that's the only setting that gives any sound at all, otherwise it's just silent.

I didn't realize that about AC3. I downloaded it and have been fooling around with it, but if the DX is already doing encoding to AC3, I suppose it doesn't really matter if I use the codec or not. I was just thinking of using the AC3 codec to send the compressed signal to the receiver without any processing by the soundcard. Now I'm starting to think that it doesn't matter that much, since the soundcard's major tuning settings are all turned off anyways.

I guess I'll just work it from here and see where it goes! My music sounds good even now without any tuning or anything, so I figure once I use the setup microphone on the receiver or something, it'll sound even better, hopefully.
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