Coaxial or Optical SP/DIF

There are probably numerous threads here (and elsewhere) comparing the pros/cons of the two types of cables. Also note that coaxial uses two kinds of connectors (RCA or BNC).

I'm no expert (on digital audio), but one thing to consider is the quality of the "implementation" behind the input/output connectors, on both source/transport and DAC.

For example, it is said that older Macs had relatively high jitter on their toslink-out, but the 2011 version of MacMini has a better (lower jitter) toslink-out.

In a recent thread here (I can't find it now) someone compared Coaxial and Optical into a NaimDAC claiming that Coax sounded better, which may point to that Naim has put more effort in the Coax-inputs than optical on the nDac.

But this may of course  vary between different DAC-products.

Some people even hear differences between cables of the same type. I know I do.  It probably shouldn't surprise a Naim owner that execution of anything can impact sound quality.  I do not know if it is settled that well-made co-ax beats similarly well executed optical.  The things you are connecting play a role, too.

One question I have about optical is whether or not, over time, the end points accumulate dirt or film that would degrade performance?  Metal connectors can be refreshed by unplugging and re-plugging.  What can one do to maintain optical connections?

Nick

The Toslink plug sits within the socket which keeps the dirt out.  You could always polish the end ot the plug with a cloth soaked in alcohol if you are worried.  I've never heard of a Toslink connection failing to work because of dirt ingress.

This is from the FAQ at the end of the nDAC White Paper:

• Why S/PDIF optical rather than coaxial?

Coax can sound better but optical has the advantage
that it prevents ground loops and isolates the ground
system of the source, which may be noisy, from that of
the Naim DAC.

One big difference between the two is that *GENERALLY* TOSLink (optical) transcievers won't go up to 24/192 and top out at 24/96 (for a reliable link) whereas electrical is stable to 192...

Phil  

again,  if you purchare a good quality opto cable that  is perfectly toshed the difference are so small,.in a noise enviroment opto is best. personal i prefer cable. some really classy opto cables out there now 

Though I notice many *quality* TOSLink transceivers are often specified around 15~16Mbps which should be more than good enough for 192/24 which is around 12.5Mbps

I believe  it was Hi-Fi world that tested the jitter of a 2011 model Mac Mini  optical output and found it's output to be in the area of 15ps, which is quite low. As I recall, the signal to noise was quite good too. Those numbers are substantially lower than the previous mac's optical output, indicating to me at least, that Apple have done something rather dramatic to the newer minis. I have also read on other forums that the 2011 mini does not support integer output on USB any longer. However, when working with the "midi" settings on my Mac, it indicates 24 bit integer output, although I have no way of verifying if it actually is.

The n-dac seems pretty impervious to differing inputs since once it grabs the incoming signal, it does what it does internally almost in a closed loop fashion. But to the OP's question - I have listened at length to the n-dac using a glass fiber optical connection and a Hallide Bridge usb to spdif hardwire. Both of them are very good and the hardwire doesn't exhibit more noise or grunge than the optical connection. There absolutely are differences though. They are small. In audio people sometimes spend big money on small differences. The optical connection presents with more layering in the soundfield, and that presentation is broader. The hardwire is a bit more upfront and maybe, just maybe, has somewhat deeper bass. It is elusive.  Timbrally, they are equal. Sometimes it seems like the hardwire has a bit more sibilance on female vocals. I find it difficult to make up my mind which I prefer. They're pretty darn good, both of them, and the differences are subtle enough to be merely  "different". If it was just about the cost, I'd go with the optical since it is much less money than the hardwire. That is my experience in my system. Listening for months now and no clear winner.

Bob

Your name seems familiar. Did you write for Art Dudley's "Listener Magazine"? It was a great read.

Your memory serves you well. I hope you enjoyed my articles as well. What strikes me most about audio from then to now is how the toslink protocol has evolved. Back then it was the lowest form of connection in the digital hierarchy, with demonstrably inferior quality. Apparently opti-couplers and interconnects are now contenders. At least those implemented in the n-dac and Apple products.