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Digital cable lengths? (both S/PDIF and USB)

70.57.64.221
Posted on May 26, 2012 at 20:12:25
willkayakforfood
Audiophile

Posts: 804
Joined: November 30, 2010
Contributor
  Since: December 24, 2011
 In a few days, I'm welcoming a new DAC into my home, and it'll need some cables. I'd like to try it with both my main system (will need S/PDIF - or optical - for this one), and with my laptop computer (will need USB cable for this).

I've occasionally come across mention of a recommended minimum length of 1.5 meters for digital cables. Does this apply to all types of digital cable? (S/PDIF, optical, and USB), or just one or more of these?

I don't intend to spend a great deal on these cables (less than $100 each), so if there are any recommendations for specific cables within that budget (new or used), I'd appreciate your ideas.

The components in question:

CD player: Virtue Audio Piano M1 (offers both coaxial and optical outputs)

DAC: Schiit Bifrost (coaxial, optical, and USB inputs)

Computer: Laptop with USB output (both 3.0 and 2.0 available).

Thanks!

 

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    ...
terminology, posted on May 27, 2012 at 08:47:31
Joe Murphy Jr
Audiophile

Posts: 4331
Joined: February 3, 2001
 Your Schiit Bifrost will actually have two S/PDIF connections: one is optical, the other is coax. S/PDIF is usually referred to as the Sony/Philips Digital Interface or, less so, the Sony/Philips Digital Interconnect Format. It's basically a protocol for transferring digital data and is not really restricted to a specific connector type (RCA, BNC, TOSLINK, ST-glass, etc).

As for the 1.5m length, there are many debates on the correctness of assigning an optimum length to an S/PDIF cable. After reading numerous threads on the matter with input from experts on digital technology, experienced audiophiles and complete morons, I have come to the following conclusion: since there are many variables involved, it really is a system dependent choice (ie, the synergy between the components involved and that of the listener to the audio gear). That said, unless you are willing to spend hours upon hours listening to various cable designs and lengths as well as testing of the components/cables with high tech equipment, you are better off getting a 1.5m cable from a respected cable manufacturer.

Now, the USB question. I could give you numerous links to back-'n-forth discussion between manufacturers, experts and rather technically minded individuals. But again, as with S/PDIF, the optimum cable length is not known due to other variables which affect the signal -- ie, there's no real agreement on the issue. Well, I'm sure they would agree that the length of the cable needs to be at least ≥ the distance between the two USB connectors. Haaa!!! In all seriousness, I would get a decent USB cable around 1m: USB uses a different method than S/PDIF to transfer data.

If you want a "no fuss" solution, I would give Markertek a call. Order a 1m Belkin Gold USB cable and have them build you a 1.5m S/PDIF cable using Belden 1694A RG6 coax cable and Canare RCA connectors. This will get you 90 - 95% of the way there with a reasonable expense. I had them build two digital cables for me and the manufacturing quality was first rate, besides the fact that the cost will be far below your budget.

USB 3.0 > Schiit Bifrost: you might want to check with Schiit on this and see if any of their current Bifrost users have reported issues using USB 3.0 with their DAC. You may or may not run into a driver issue. A phone call or email only takes a few minutes.

 

RE: Digital cable lengths? (both S/PDIF and USB), posted on May 27, 2012 at 08:49:15
audioengr
Manufacturer

Posts: 5385
Location: Oregon
Joined: April 12, 2001
Contributor
  Since: July 30, 2001
 It applies to all digital cables, AES, USB, Firewire and S/PDIF.

Steve N.

 

I was just about to recommend Markertek & 1.5 meters, posted on May 27, 2012 at 10:26:54
John Marks
Industry Professional

Posts: 3630
Joined: April 23, 2000
 The theory behind the 1.5 meter length is that whatever reflections come back from the far end of the cable will arrive in the "fat part" of the "digital eye" and not where the signal is crossing the zero axis, which would be expected to cause "crossover notch distortion."

But as mentioned above, results can be expected to vary quite a bit, dependent primarily upon the reflection and jitter tolerance or immunity of the receiving unit, in this case, the DAC.

Markertek's digital cables are good. To get into diminishing returns, I have found both Cardas and Nordost cables to be excellent, but are a lot more money.

One experiment I have not tried is to send a Markertek digital cable out for cryogenic processing. But life is short and there is a lot of great music to listen to.

JM

 

Thanks audioengr, Joe, and John!, posted on May 27, 2012 at 13:18:47
willkayakforfood
Audiophile

Posts: 804
Joined: November 30, 2010
Contributor
  Since: December 24, 2011
 Well, I'm moving fast on this, and it looks like I'll have a few different cables to try...

So far, I've ordered:

1.5 meter Belden 1694A w/Canare RCAs, from Blue Jeans Cable (they're local)

1.5 meter of Canare terminated "home brew" digital cable from Rob Fritz's "assembly tech" person at Audio Art cables

I've also ordered a Belkin Gold USB cable (the one I found was 6 feet - I hope that's not too long).

I've been told about the DH labs "Silver Sonic" USB cable ($80 for 1.5 meters), so if I do end up using this DAC for the computer system (in which case I'd order another Bifrost, without USB input, for my main stereo), do you think I might suffer too much "diminishing return" with the DH Labs cable? (see link to this cable, below). Or, might it get me to that last 5-10%? :)

Thanks again!

 

RE: Digital cable lengths? (both S/PDIF and USB), posted on May 27, 2012 at 13:25:19
Duster
Audiophile

Posts: 9533
Location: Pacific Northwest
Joined: August 25, 2002



While an optimum 1.5m length is not available as a readymade option, the deep discounted AudioQuest VSD-5 100% PSS Perfect Surface Silver digital coaxial cable is an outstanding 75 Ohm pure silver cable for the price (2m - $49.99). If one can DIY, the product is also available per the foot in bulk which allows the length of one's choice, and the selection of higher performance connectors if desired. I use a DIY VSD-5 for my DVD player as well as a stellar DIY composite video cable for my digital CATV terminal. While the stock AudioQuest rca connector is rather mundane, at least it's a compression type termination for potentially better 75 Ohm impedance characteristics for digital applications.

See link:



 

Thanks Duster! I'll keep this one in mind as well. (nt), posted on May 27, 2012 at 13:31:58
willkayakforfood
Audiophile

Posts: 804
Joined: November 30, 2010
Contributor
  Since: December 24, 2011
 *

 

Digital cable myths, posted on December 9, 2012 at 07:43:49
Thanatos
Audiophile

Posts: 2
Location: Seattle, WA
Joined: September 11, 2012
 I have to chime in here, despite the fact that I know this is a very old thread.

There is no optimal cable length when dealing with digital cables, nor should there even be any debate regarding this. That there is just indicates a vast misunderstanding between cable types.

A digital signal is 100% immune to anything and everything that might plague an analog signal like an interconnect or speaker wire. The only thing to be mindful of when dealing with digital signaling is maximum cable run, which for USB is 5 meters and for coax (S/PDIF) is 10 meters. Cat5/6 ethernet is ~50 meters.

The primary difference between analog and digital (and why cable type and length don't effect the quality of the signal) is the fact that with a digital signal comes Error Detection & Correction, which leads to a binary state for the signal: It is either *PERFECT*, or it is broken and the application that is using that signal reports an error to you (or simply crashes) The application or device sending the data and the application or device receiving that data *GUARANTEE* it by checking every single byte that's transmitted to ensure that the data is being received *exactly* as it was sent.

THERE IS NO IN-BETWEEN. PERFECT, or non-functional.

That's it. That's the ONLY possible two states the cable can have. This is why there is no such thing as an "optimal" length because you cannot optimize PERFECT. This is why the quality of the cable can not possibly improve, or degrade, the sound you hear.

This is why I get so upset when I see people spending gobs of money for digital cables. If you spend more than $5 for a USB cable you are, flat out, being ripped off and if as some have posted here you're actually spending hundreds of dollars on these cables you are in desperate need of some adult supervision.

Digital cables don't need to be made out of Gold, don't need shielding, don't need *anything* that analog cables can benefit from, because the signal on a digital cable can *not* be influenced by outside signals. Moisture and heat can affect the cable, but that causes physical damage which leads to one of the binary states: Non-functional.

This is why cheap digital cables can and are used in mission critical, as in "people die if the signal gets screwed up" applications like the control stations of nuclear reactors.

Stop being ripped off. When it comes to digital cables there is never any need to build your own, buy gold plated, or worry about the "optimum" length, because you cannot optimize or improve upon... perfect.

 

RE: Digital cable myths, posted on December 9, 2012 at 13:10:09
pixelphoto
Audiophile

Posts: 234
Location: So. Cal.
Joined: December 15, 2009
 Hi Thanatos, is what you posted applicable to Toslink glass or plastic cable?

Marvin

 

RE: Digital cable lengths? (both S/PDIF and USB), posted on December 10, 2012 at 19:04:27
josephelias417@gmail.com
Audiophile

Posts: 7
Location: so. cal.
Joined: December 10, 2012
 Hey there friend, I just replaced all my SR cables and Nordost with a slew of great cables. I've been stradily breaking them in and I highly suggest you look at laceyacoustics. A new company but the cables are simply amazing, especially the SA-1 and the Palladium digital. I bout 3 Palladium digitals as well as a few sets of interconnects and was blown away by the performance. They have tons of knowledge and really know what they are doing. Like I mentioned it is a new company and I think they have a big add in The absolute sound in January fom what I'm told. All I can say is check them out. I will more info in the next few days as I have only been using them for about a week but WOW....really nice cables and I think you would really like the digital units they have....keep me posted and good luck! Very excited about these cables!

 

Forgive me if I'm wrong, but something smells..., posted on December 10, 2012 at 20:25:04
willkayakforfood
Audiophile

Posts: 804
Joined: November 30, 2010
Contributor
  Since: December 24, 2011
 You just joined the Asylum today, and as of this typing, you have four posts. All four posts are pushing "laceyacoustics" cables, and are strikingly similar in their wording; like half-baked advertising copy.

So how's your new business going? Also, learn to spell. :)

 

RE: Forgive me if I'm wrong, but something smells..., posted on December 10, 2012 at 20:39:25
josephelias417@gmail.com
Audiophile

Posts: 7
Location: so. cal.
Joined: December 10, 2012
 No, just joined to look around for users that have mixed some computer based audio into their 2 channel. I just finished up my 2 channel/multi channel set up, actually downsized a bit. Looks like most are going in the same direction, so I am also looking into a new dac as well. Just love the new stuff....any suggestions? Would love to stay away from anything HDMI.

 

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