Why do digital cables sound different?

I have a (hopefully) simple question. Now that we are using 24/96 music and lets assume also 24/192, does that change the requirement on the "Freq Resp dc - 40 MHz" type of rating? What MHz is required? Interesting that Kimber D60 (quite expensive) is 40 MHz and the rest of their cables are 20.

Also, I can't find that value for the Belden 1694A, does anyone know? It seems like that is a great reference digital cable at extremely low cost - yet *many* of the issues raised here have been addressed, by degree, by that cable. At an insanely low cost ala Blue Jeans and others.

Original post on 12-01-00: Why do digital cables sound different? After much discussion, may I venture that, as of 07-02-09, the question has not been answered?
Could it be possible that no one knows? 8^)

Rja

Question has been answered many times. Digital cables introduce jitter. Jitter creates sidebands at very small level not harmonically related to root frequency. It is basically noise in time domain. Noise is reducing resolution, imaging, clarity etc.

Jitter is induced in coaxial cables by external noise or characteristic impedance mismatch (signal reflects on impedance boundaries). In Toslink jiiter is induced by system noise in presence of slow rise/fall time (slow transmitters and receivers).

It is possible that we could summarize a few points:

If you DAC re-clocks really really really well (and most very modern ones focus on that now in varying degrees)

and

If your SPDIF cable is 2 meters or so (not less)

and

It is rated somehow to maintain 75 ohms within very tight tolerances every few mm along its length

and

its termination methodology maintains the 75 ohm aspect

then the difference in cables should be pretty minimal.

In that sense are we getting somewhere over the 8 / 9 years?

Lightminer - If DAC reclocks like Benchmark (asynchronous upsampling) then quality of the cable is not of importance. Benchmark tested it with thousand feet of CAT5 network cable and it did not show any audible effect. The reason for that is few Hz jitter bandwidth of the Benchmark providing suppression in order of -100dB at the frequencies of interest (kHz) on the top of already low level of jitter (order of -80dB).

For traditional non-upsampling DACs I would look for 1.5m coax (Toslink gives about 2x jitter) double or even triple shielded with high quality connectors. I would also look for the transport with slew rate in order of 5ns instead of typical 25ns and very good power supply (to minimize system noise induced jitter).