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BNC or RCA digital cable question

mudlark said:
A clock signal can be fully reconstituted by a good PLL system. Creating a separate clock signal as happens with async means the cable is a minor issue.
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It's a non issue with a well designed converter (Eximus DP1 etc) to my ears, though some my say otherwise. Obviously, that doesn't mean you shouldn't make (Silver Mogwai) or buy the best S/PDIF cable possible, it's just not always required. You can test this to your hearts content with a good AD-DA converter, PC sound card etc., but many would rather read and guess.

Peter
 
DevillEars said:
The connectors do not define the impedance of the interface - that is largely driven by the cable/conductors used. The single-ended or unbalanced coaxial electrical interface spec for S/PDIF calls for a 75ohm impedance across the interconnect (from one connector via the cable to the other connector) and also allows for a choice of connectors - either RCA or BNC.

BNC connectors are more popular in pro-audio than RCA as they are a locking design and when inserted require a twist to engage the locking pins (RCA connectors can be pulled out if the cable is kicked). As far as sonic differences are concerned between connectors, if all else is equal (ie: the cable/conductor make-up) then there are unlikely to be any significant audible differences.

The areas where cable differences can be introduced are:

1) The quality of connector used (material, build-quality and conductive plating)
2) The quality of conductor used (material, impedance matching to standard 75-ohm spec)
3) The jointing between conductor and connector (soldering, crimping, etc)
4) Cable geometry (how conductors are assembled to minimise cross-talk)

So, for a given "model" from a reputable cable manufacturer, you should not encounter any significant audible differences between RCA and BNC terminations.

Dave
Click to expand...

Dave and anyone else

Forgive the hairsplitting, I guess your 4 points were general principles mainly applicable to analogue not digital cables.

How does cross talk happen with digital signals passing along cables?
 
mudlark said:
"There will be a difference, but whether it's significantly audible, only you can tell."

The above words don't make any sense at all, in fact they display a fundamental misunderstanding of digital data transmission.

A clock signal can be fully reconstituted by a good PLL system. Creating a separate clock signal as happens with async means the cable is a minor issue.
Click to expand...

Not quite. Differences have been measured between coax cables, using a modern DAC, at the output of the DAC.

The differences, in the case I know about anyway, were very small and are probably not audible.

But it does scupper the general argument that there is no mechanism for coax cables to affect the performance of the DAC.

So arguing about audibility is more in accordance with facts than arguing no difference is possible.
 
darrenyeats said:
Not quite. Differences have been measured between coax cables, using a modern DAC, at the output of the DAC.

The differences, in the case I know about anyway, were very small and are probably not audible.

But it does scupper the general argument that there is no mechanism for coax cables to affect the performance of the DAC.

So arguing about audibility is more in accordance with facts than arguing no difference is possible.
Click to expand...
Are you aware of any experiments that show that the same cable remains the same?

Paul
 
Repeatability taking into account measurement error is part of any good experiment.

That we probe more often when results contradict our beliefs, is a matter for psychology of course, not physics.
 
I think it's likely (in this case) that we don't probe enough when results confirm our beliefs.

I'm quite interested in the variability of the same process, I think it might be time for some more DAC research.

Paul
 
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