RCA or XLR Between Digital Separates?


Hi I'm awaiting Antelope Zodiac basic DAC and wonder if there are any advantages/disadvantages between RCA and XLR digital cables used.
marakanetz
Please consider this post more general with any DAC with digital balanced inputs than particular to Antelope Zodiac. Which digital interconnect would sound better balanced or RCA?
I doubt there will be an audible difference, but XLRs are always better than RCAs for everything. I can't think of an exception.
Agree with Irvrobinson. The "balanced" format is what is used exclusively in the pro/studio world-for good reasons mentioned here many times. The XLR is 110 ohms vs the RCA 75 ohm format so they are not directly interchangeable, you can easily mix and match.
I was under the same impression but read in recent reviews that spdif was superior. Does anyone have any experience?
Like 99.9999% of the questions, it all depends on the component and cable. Last month I demoed an expensive highly regarded DAC at home for a week and found AEB/ESU was much superior to RCA eventhough the RCA digital cable is 3X more expensive. The only way to know for sure is try both in your system.
really depends on the data stream that is being transported and the length of the cable. For CD's bit rate 16 bit / 44.1khz, and cable lengths under 6 feet, likely no difference.

At the data stream rate is increased to 24 /96 or 24 /192 then you're quicky running out of bandwidth, and have to move to an XLR Digital cable.

On the pro side, everything at 24/96 and up is all XLR, or twin XLR, in a double wire double speed config.
"Like 99.9999% of the questions, it all depends on the component and cable. Last month I demoed an expensive highly regarded DAC at home for a week and found AEB/ESU was much superior to RCA eventhough the RCA digital cable is 3X more expensive. The only way to know for sure is try both in your system."

As long as the cable has proper impedance and reasonable capacitance the XLR design wins hands down. You can buy the best solid silver RCA cable half an inch thick and compare it to any cheap-o balanced cable you can buy in a music store and the XLR to XLR signal transmission will be superior. For short distances, like less than 15 feet, the difference is often not important or audible. Balanced cables use differential signalling, which puts the portion of the waveform below the reference voltage on one conductor and the portion above the reference on the other conductor, with a common ground. That's why you see three pins in an XLR connector.

At the receiver the signals are recombined at some point, and the combining process produces a phenomenon called common mode noise cancellation. This allows much longer cable runs without signal degradation, and that's why balanced cables are used for pro audio and microphones. Consumer audio tends not to use balanced audio because the circuitry is more expensive, the connectors are more expensive by far (except for perhaps WBTs), and for short runs, like I said, there may not be an audible difference.

The differential signalling advantage applies to analog and digital signalling equally, because on a cable it's all really analog.

RCA cables are "single-ended" and that's an inherently inferior signalling technique.

So, will a well executed RCA design with a reasonable cable be better than a poorly executed balanced design? Yes, of course. But otherwise balanced cables are the way to go.
12-17-11: Irvrobinson
As long as the cable has proper impedance and reasonable capacitance the XLR design wins hands down. You can buy the best solid silver RCA cable half an inch thick and compare it to any cheap-o balanced cable you can buy in a music store and the XLR to XLR signal transmission will be superior. For short distances, like less than 15 feet, the difference is often not important or audible. Balanced cables use differential signalling, which puts the portion of the waveform below the reference voltage on one conductor and the portion above the reference on the other conductor, with a common ground. That's why you see three pins in an XLR connector.

...

So, will a well executed RCA design with a reasonable cable be better than a poorly executed balanced design? Yes, of course. But otherwise balanced cables are the way to go.
Well, not from my practical experience. Years ago I had a Benchmark DAC1 w/PCX mod and in my system, the $140 BNC Stereovox XV2 surprisely crushed a Kimber AEB/ESU in $1K range and DH Labs AEB/ESU in $300 range. It's a long time ago so don't remember the model#s.

Later I tried a Zu Ash AEB/ESU and it was the best cable I've heard in the system.

Theory is one thing but design / execution of the design is another.
Knghifi, your position is that one properly constructed cable that meets specifications can "crush" another? I don't live in that universe. Sorry.
Thanks, guys. I am comparing now - a Tara Labs "the One" spdif and a Purist Audio 20th Anniversary Actures XLR. Need to warm up the XLR a little more but it may have a deeper soundstand and be a little (little) more resolving but the bass is (maybe) not as tight, but that could be warming up/breaking in. The XLR cable was broken in but not used for 6 months or so. The cable is between an Esoteric G25u and a Berkeley Dac. Source is PC/Win 7/JRiver16/ESI Juli@.
12-18-11: Irvrobinson
Knghifi, your position is that one properly constructed cable that meets specifications can "crush" another? I don't live in that universe. Sorry.
Irvrobinson, I'm simply saying you just can't assume a AEB/ESU cable is ALWAYS superior to a RCA cable without listening them in your system.
XLR's have much greater noise reduction by design. My personal experience with cables is that XLR's have a much more expansive soundstage.
While in general I would expect an AES/EBU interface to provide superior performance, for the reasons that have been stated (and also due to reduced susceptibility to jitter that may be induced by ground loop effects), the following are some factors that might tip the balance the other way in some cases:

1)The AES/EBU signal may have faster risetimes and falltimes, which could worsen waveform distortion caused by signal reflections resulting from imperfect impedance matches, thereby causing increased jitter.

2)The cable and connectors used for S/PDIF may have more accurately controlled impedances than those used for AES/EBU, especially if BNC connectors are used for S/PDIF. I would expect a coaxial cable (used for S/PDIF) to provide more accurate impedance control than a twisted pair shielded cable (which is commonly used for AES/EBU).

3)Keep in mind that by changing from one cable type to the other a lot more than just the cable is being changed. The interface circuits in both of the components that are being connected are being changed, and there is no telling how the quality of the two interface circuits may compare.

4)While going to AES/EBU may reduce noise-induced jitter that would occur with S/PDIF (as opposed to jitter that may result from waveform distortion caused by impedance mismatches), depending on its spectral content a reduction in jitter could conceivably result in subjectively worse sound. As stated in this paper by Steve Nugent:
Another interesting thing about audibility of jitter is it's ability to mask other sibilance in a system. Sometimes, when the jitter is reduced in a system, other component sibilance is now obvious and even more objectionable than the original jitter was. Removing the jitter is the right thing to do however, and then replace the objectionable component. The end result will be much more enjoyable.

Jitter can even be euphonic in nature if it has the right frequency content. Some audiophiles like the effect of even-order harmonics in tubes, and like tubes, jitter distortion can in some systems "smooth" vocals. Again, the right thing to do is reduce the jitter and replace the objectionable components. It is fairly easy to become convinced that reducing jitter is not necessarily a positive step, however this is definitely going down the garden path and will ultimately limit your achievement of audio nirvana.
Regards,
-- Al
THANKS!
My post meant to generalize theoretically utilizing balanced or RCA connection between digital separates regardless of brand/wire quality and get the idea of advantages/disadvantages using one to another specifically in digital domain. My analogue in/out domain is fully balanced except phonostage and that's where I would less likely switch to unbalanced RCA even for the short wire runs.

Jitter is one of the issues I want to minimize since especially on the higher frequencies I can hear things different from real sound such as hissing, whistling and sometimes inconsistency especially if compared to the vinyl version of the music.

From this discussion I realized that technically the difference between both connections should not be subtle.

Thanks for all your contributions.

Mark M.
Al, you never cease to amaze me. I enjoyed your post. Interesting points, but balanced cables are still my preferred dance partners. :-)
Al,
I too enjoy your erudite and illuminating posts. Thanks!

I have used many high quality AT&T Glass, XLR and BNC cables between various transports and DACs and have found there is no way to predict which will work best with any given combination.

As an example; I recently replaced an expensive and highly regarded XLR cable, which worked great in other systems I've owned, with a relatively inexpensive BNC cable. The BNC cable bested the XLR cable in every respect in this particular application.

So unfortunately, as much as it would make life a bit simpler, there's no theoretical way to select the "best" digital cable. I'm always surprised by how different digital cables can "sound". I remember the old "bits is bits" days fondly.
Thanks very much, guys. Enjoy!

Best regards,
-- Al
Rja, that's EXACTLY my point. I guess we live in the same universe.