Optical Digital vs Analogue

[grangervoldemort]

Please note my questions are numbered. Please try to answer all of them in your reply.

 

Thank you.

My audio setup is as follows:

 

Asus Xonar D2X -> 3 x 3.5mm cables, male on both ends -> One side of the cables go into the Xonar D2X the other into the Logitech 5.1 Z5500

 

So for years I have had it so that it works using the 3.5mm analogue cables.

 

I discovered today that my soundcard has SPDIF. Until today I didn't know what it was.

I assumed that the Xonar D2X didn't have optical digital out and never knew what SPDIF was and thought only RCA style cables go into it (I still don't know if any other cable other then a SPDIF adapter (supplied with the sound card) can go into it.

A quick check on guru3d's 2008 review on the card shows: ''

• S/PDIF input and output, both with optical and coaxial connections'

So there is something called coaxial. 

 

1) What is this coaxial and does it work using light, like optical digital TOSLINK?

 

I tried connecting my PC to my Z5500 using the adapter. The cable supplied looks like a toy. it is plastic. I was like What the..., this must be a joke.

It worked.

 

2) I wonder if the quality of this cable affects the sound? I assume as it's digital it makes no difference?

 

I switched between Analogue and Digital using both the Z5500 and the Xonar D2X Control Centre.

 

The control centre has only these options for the SPDIF out:

> PCM

> Dolby Digital Live

> DTS Interactive

> S/PDIF In Loopback

 

3) What are all these options and why and when do I use each one?

 

4) When I put it on PCM I get no sound and my Z5500 shows 'No digital data'. Why?

After trying it out I noticed that Optical sounds a tiny bit worse and is quieter.

 

I have read that by using digital you bypass all the good high quality audio processing of the sound card and pass that job onto the receiver (in this case the Z5500 speakers).

So it is said that analogue output is better quality.

 

5) Is that true and if so can you please explain how? 

 

I am renovating my room soon, so it would be nice to be able to get rid of the 3 cables and use this short digital cable instead. Sound quality takes priority thought of course, so if digital output is worse please tell me.

 

[KarathKasun]

Coaxial just means "RCA" in effect.  RCA cables are coaxial style with the signal in the center and the ground wrapped around the signal cable.

 

Quality is the same between coaxial and optical cables (they both transmit the same digital signal, quality is exactly the same as long as the signal gets through), optical can be significantly longer though.

 

The options are for the encoding format.  Not all digital audio devices support the same formats, that is why there is an option for it.  You simply pick what is supported by your setup and leave it (in most cases).

 

Digital vs Analogue quality depends on the length of cabling and quality of encode/decode circuitry.  On cheaper setups that support both, there will be minimal difference.  However, if the device only supports old or outdated encoding, analogue will likely sound better due to support for newer/better processing on the PC side of the equation.

[grangervoldemort]

Thank you for your reply but you haven't really answered my questions.

 

Anyone else who replies please answer all of my questions one by one. Thank you.

[KarathKasun]

1 hour ago, grangervoldemort said:

Thank you for your reply but you haven't really answered my questions.

 

Anyone else who replies please answer all of my questions one by one. Thank you.

OK, Ill make sure to put bullet points in this time.... When reading, imagine I am speaking very slowly and loudly.

 

1) Coaxial = RCA  Coaxial is just a type of wire, and in home audio use, it has RCA ends on it.

 

2) NO

 

3) You use whatever works with the equipment you hook up to the digital output.  Google or your user manual can help picking which one to use.

 

4) Your speakers do not support whatever PCM format is being output by your computer, there is another setting to fix this in the windows audio settings (specifically the sound quality setting, 44,100/16bit is likely what you need).

 

5) Digital vs Analogue quality depends on the length of cabling and quality of encode/decode circuitry.  On cheaper setups that support both, there will be minimal difference.  However, if the device only supports old or outdated encoding, analogue will likely sound better due to support for newer/better processing on the PC side of the equation.

 

TL/DR 5) Use whatever sounds best to you.

[JZStudios]

So, what I know is that the three 3.5 jacks will give you full uncompressed surround sound (Also known as LPCM) whereas the S/PDIF only gives PCM for stereo and Dolby Digital decoding.

LPCM (Linear Pulse Code Modulation, same thing as PCM just includes an L) is basically uncompressed. The problem is that S/PDIF really only supports stereo, so you'll only get uncompressed stereo.

Dolby Digital and DTS are both surround sound encoding, in this case, decoding. It's what comes on DVDs because they don't have enough space for uncompressed audio. The short version is, it's still a stereo signal that's being transmitted, but encrypted with data. The device with a decoder then outputs the audio to all channels. It's not as clean as the 3.5 analog (Assuming the source isn't DD) and AFAIK only supports 5.1.

I don't know what S/PDIF loopback is, but a quick Google search appears to be something used for recording audio.

 

TLDR, 3.5 analog has better audio and surround capability.

Fun Fact: S/PDIF was introduced in 1998, and to this day it's never been updated, nor do we have a simple single cable for LPCM surround sound exclusively.

[EsaT]

2 hours ago, grangervoldemort said:

 The control centre has only these options for the SPDIF out:

 

> PCM

> Dolby Digital Live

> DTS Interactive

> S/PDIF In Loopback

 

PCM means Pulse Code Modulation, that's uncompressed audio data.

Because of age of standard SPDIF wasn't designed for more bandwidth than two PCM channels.

 

Dolby Digital Live makes sound card use DD5.1 encoding.

DTS Interactive again uses DTS encoding, also capable to 5.1.

Those are the ones needed for getting 5.1 over SPDIF.

 

And it's well possible that sound card has better DACs than that speaker set.