Why do digital cables sound different?

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).

So may I assume that the less jitter a digital cable induces the "better" that cable will "sound"?

Is this induced jitter measurable from cable to cable? Could an absolute "best" be established using the lowest jitter criteria. And if this is true, why are so many digital cables (100s or more) available?

Or, is this purely a theoretical discussion?

Rja - AFAIK jitter is the only difference between digital cables. I don't know of anything else that can affect the sound. Jitter can be measured but many factors can change it - like level of electrical noise around, amount of system noise etc.

One cable might work very well, having perfect impedance matching, with fast slew rate outputs while the other might offer perfect shielding - important with slower transitions especially in noisy environment. In addition there are preferences of flexibility, color and overall quality. There are, of course, identical performance cables offered by different companies - same as with analog interconnects.

Why do you want to establish absolutely the best ($$$$)? My system and my ears are perhaps not good enough to appreciate the best cables (analog or digital).

I would still trust my ears or reviews more than measurements. Don't spend money if you cannot hear the difference.