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dumbo
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Question on PC Sound Card SPDIF Out to DAC Cable lengths

Hello,

I was curious to know if anyone has done any testing or has some scientific data on the maximum recommended distance a Digital cable should be between two components without signal degradation or issues?

In my case, I am referring to a cable run that would originate from an SPDIF-Out from a sound card to an SPDIF In on my DAC directly downstairs from my PC location.

I know it's kind of a silly question as in most cases a short cable run is ideal but I'm trying to determine if I should plan on moving a dedicated PC near my other Audio equipment (not desired) or if the current 20ft distance is within range without a negative impact on sound.

My initial thoughts on this would be that this MAX distance is dependant on the voltage output value of the card feeding the SPDIF output signal to the external DAC but I could be wrong.

What are the majority of other folks doing that may be in the same situation? I would really hate to move a PC into the listening area.

Thanks for any info you can provide.

Please feel free to move this post into the Cable section of the Forum if that is a better fit but I could decide since it's a topic kind of on the fence

struts
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Re: Question on PC Sound Card SPDIF Out to DAC Cable lengths

Hi there dumbo.

The S/PDIF standard is goverened by IEC 60958-3 which specifies the voltages (min 0.2V in, max 0.6V p-p out) and maximum cable length (10m). In practice the critical electrical property of a S/PDIF cable is the impedance (75 ohms) - there's a thread on this up in the cable forum.

Anyway, bottom line is that you'll be fine with a 20ft cable as long as the impedance is correct. A good budget choice is Belden 1694A. A 20ft cable will cost you $28.

An alternative approach which avoids the need for wires in the stairwell as well as offering remote control from within the listening room is to use a wifi streamer like a Logitech Squeezebox.

Elk
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Re: Question on PC Sound Card SPDIF Out to DAC Cable lengths

I've used an inexpensive 50' Monoprice.com S/PDIF cable Yes, only $5.75.

It has connected a desktop and a Focusrite outboard digital audio interface (connected via firewire to a laptop) to a Benchmark DAC with zero issues.

I would go ahead and do it.

struts
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Re: Question on PC Sound Card SPDIF Out to DAC Cable lengths

Very interesting indeed Elk. I am guessing that at that cable length the waveform is starting to get noticeably deformed. I wouldn't expect good results unless the DAC has good jitter rejection, which of course the Benchmark does. However, at $5.75 it's a cheap theory to test!

Still wondering how the OP is intending to control the music (PLAY, STOP, NEXT etc.) from the listening room.

Elk
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Re: Question on PC Sound Card SPDIF Out to DAC Cable lengths

I was surprised that it works as well as it does. I expected some sort of issue, beginning with the DAC not being able obtain a lock.

It is a tough scenario, long cable and the length not needed I leave coiled.

I need to test this with the Grace also. My guess is that it also will not blink.

dumbo
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Re: Question on PC Sound Card SPDIF Out to DAC Cable lengths

Hey Thanks for the info.

Glad to see that my 20ft run is within distance. I'm not sure what kind of impact the additional length would have on things like jitter but I am using a BelCanto DAC3 which is pretty good about looking past additional jitter within reason.

In terms of controling Play/Pause/Stop etc I was planing on just going about it the old fashioned way combined with a carefully created Playlist so I don't have to run up and down the stairs too much.

I guess if I get real lazy I can always open a port on the router and use RDP Lite with my iPhone to connect to my machine upstairs but that would be pretty sad

struts
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Re: Question on PC Sound Card SPDIF Out to DAC Cable lengths

Well don't let me talk you out of a good source of exercise but I would say that remote-controlled access to one's complete (ripped) CD collection is one of the biggest benefits of computer-based audio, not to mention one that is hugely appreciated by the rest of the family. I would go so far as to say you would really be missing out if you didn't implement some way of controlling the system from the listening room.

If, as you imply, you already have a wifi network I would really recommend you look at the Logitech Squeezebox which would solve the long-cable problem and the control problem as well as providing access to internet radio etc. all for $263. I don't want to sound like a shill for Logitech (I actually own a competing product) but going this route takes you much further than just adding the PC as a source. It really transforms the whole audio system and the way you use it. Once you've tasted the convenience I don't think you'll want to go back.

End of sermon. Good luck!

dumbo
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Re: Question on PC Sound Card SPDIF Out to DAC Cable lengths

Thanks again, I appreciate everyone sharing their experience in this type of setup. I did, at one point look at the Logitech SB and almost pulled the trigger on one until I noticed that they would be coming out with a "Touch" model which hasn't seemed to surface yet. I believe the touch is supposed to support 24bit files and the standard SB is limited to Red Book resolutions.

I may hold off a little while longer and see if a touch model surfaces from Logitech. I would have to agree with you that it would be nice to have the music libary in the palm of my one hand and a fresh microbrew in the other without all that exercise stuff

struts
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Re: Question on PC Sound Card SPDIF Out to DAC Cable lengths


Quote:
I believe the touch is supposed to support 24bit files and the standard SB is limited to Red Book resolutions.

Close. The (now discontinued) Classic supports up to 24/48 whereas the new Touch (due in stores in early April I'm told) supports up to 24/96.

I mentioned the Classic and not the Touch for a couple of reasons:

  • It is available
  • It supports sufficient resolution for 99% of people's music
  • There may be some bargains to be had as retailers clear inventory

However, if 24/96 might be important to you then I'd say you're right to hold off and go for the Touch.

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