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How do you adding a optical and/or coaxial audio output to your computer and little else?

post #1 of 10
Thread Starter 

Hi
I purchased a DAC which has both optical audio and coaxial audio inputs available to it. It also has a USB audio input which I thought might be the way to go if I was only traveling a short distance to the DAC. However presently I am using a USB repeater cable which goes 82 feet over to the other side of my basement from my computer where I intend to do my music listening. The DAC I chosen has its own internal power and consequently doesn't rely on USB power through this 82 foot cable, but I thought perhaps the voltage swing at the end of this cable may be less than optimal. Perhaps it's optimal enough to satisfy my DAC which hasn't arrived yet. But if it isn't here is my question.

 

 

I wish to know how to add either earn optical audio output or coaxial audio output to my computer which now has none without buying an elaborate soundcard which would make me purchase a lot soundcard on board circuitry which will not be used. So are there either good quality conversion USB to optical audio converters or the same for coaxial audio output? Or the same for cards which will plug into one of my desktop PCs card interfaces? I would like it to do minimal processing just convert output to either optical audio or coaxial audio or both with minimal processing and minimal undo expense.


Edited by bbmiller - 2/18/14 at 4:25am
post #2 of 10

USB->S/PDIF converter might be the easiest solution but ... depends on the supported modes you need, a good one (which supports 16/24-bit & 44.1-192kHz) costs about the same or even more than an USB audio interface with S/PDIF I/O.

 

http://www.audiostream.com/category/usb%E2%80%93spdif-converter-reviews

 

Some motherboards do have S/PDIF output ... does yours?

post #3 of 10

An 80 foot USB cable is likely to be a problem... Someone more knowledgeable will surely chime in and explain this better than I can.

post #4 of 10
Thread Starter 
Quote:
Originally Posted by jiiteepee View Post
 

USB->S/PDIF converter might be the easiest solution but ... depends on the supported modes you need, a good one (which supports 16/24-bit & 44.1-192kHz) costs about the same or even more than an USB audio interface with S/PDIF I/O.

 

http://www.audiostream.com/category/usb%E2%80%93spdif-converter-reviews

 

Some motherboards do have S/PDIF output ... does yours?

I have a USB soundcard called the Creative Labs Sound Blaster X-Fi HD Products Model: SB1240 which does have such a input and output however I am not getting creative lab tell me anything about its capabilities and whether if I use it I have to use a DAC in this Creative Labs card. It would not make sense to go through a very low-quality DAC to get to a much higher quality DAC. So I could use it locally next to my computer with a fiber-optic cable but how do I find out about its capabilities and whether it will downgrade my audio quality which is the whole point?

post #5 of 10

Digital is digital, meaning if you send the signal through the optical output, it will bypass the soundcard's internal DAC and send the digital signal straight through the output.

post #6 of 10
Thread Starter 

I'm afraid I got confused and misspoke. I do not want to send it right into the optical input and then use the optical output. I would like to use the USB input and user it as a converter to convert to optical output.

 

I know with the software that comes with   it has sort of processing capabilities. When you use it with its USB input and also use its RCA jacks audio output it to manipulate the sound in many ways. It can expand the dynamic range. It can emphasize the voice frequencies. It can simulate concert Hall sound. 

 

 

So if I was to use its USB input and its optical output would I be going through any of that or absolutely none of it as I would like to be the case?

post #7 of 10

None of it since the signal remains digital. The only way the sound will be affected is if it goes through the digital ---> analog convertion, so long as you output the signal through one of the digital outputs (optical, coaxial, USB), it will be unaffected. If you use the RCA output, then the signal will go through the soundcard's DAC chip.

post #8 of 10
Thread Starter 
Quote:
Originally Posted by elmoe View Post
 

None of it since the signal remains digital. The only way the sound will be affected is if it goes through the digital ---> analog convertion, so long as you output the signal through one of the digital outputs (optical, coaxial, USB), it will be unaffected. If you use the RCA output, then the signal will go through the soundcard's DAC chip.

I would love to get my hands on a schematic of the card we are talking about but don't know how to get one.

 

 

But do you or anyone know of any schematic of even a different soundcard that will show what you are saying. If anybody in these forms can post a schematic diagram of a soundcard that shows that that would simply be very great. I mean to be exactly specific about it shows that if you go from a USB input to a optical output you could see it right on the schematic that it is not going through any DAC's also.

post #9 of 10

You don't really need any schematics - the signal simply stays digital, USB/coaxial/optical inputs/outputs only carry a digital signal (1s and 0s), the whole point of a soundcard having a digital output such as optical/coaxial outputs is so the signal can be carried through while bypassing the soundcard's DAC.

 

A soundcard design where the digital signal would go through the DAC chip, then out the digital outputs is simply impossible without doing another ADC (analog to digital converter) conversion, meaning that your signal chain would look like this:

 

USB (digital) ---> Soundcard's DAC chip ---> Soundcard's ADC chip (which it doesn't have, obviously) ---> Digital output (coaxial or optical). This would be completely pointless, no engineer would design things this way. If you're sending your signal through USB, then it is digital, and if you output it through coaxial or optical, then there is no way it goes through the digital ---> analog conversion since the optical output is a digital output, it won't be able to output an analog signal.

 

Hopefully I was clear enough to be understood, english isn't my first language.


Edited by elmoe - 2/18/14 at 12:30pm
post #10 of 10

As said, if you put the X-Fi HD USB into work to output through S/PDIF Output port, the signal path is USB cable --> X-Fi HD USB:S/PDIF Output --> your external DAC input.

Isn't this the same as it would be when using some USB to S/PDIF converter?

 

As said, long USB cable may be problematic ... and ofcourse, a long Optical (TosLink) cable expensive.

 

By review of X-Fi HD USB : "For the digital inputs and outputs, the product offers stereo playback and recording formats of 16 bit, 44.1, 48, and 96 kHz and 24 bit, 44.1, 48, and 96 kHz".

http://www.hardocp.com/article/2011/09/20/creative_xfi_hd_usb_sound_card_review/2


Edited by jiiteepee - 2/18/14 at 2:09pm
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