Why do digital coax cables matter?

Was just reading about how 1.5m is the best length for a digital cable. Something to do w/ reflections. I read somewhere else that all interconnects can benefit from being 1.5m. Somehow that doesn't sound right to me. So, is it true- will 1.5m RCA interconnects going from my DAC to my pre amp sound better than the 2 ft length I am currently using? Thanks

Mrblackcrow 8-26-2017
I read somewhere else that all interconnects can benefit from being 1.5m. Somehow that doesn’t sound right to me. So, is it true- will 1.5m RCA interconnects going from my DAC to my pre amp sound better than the 2 ft length I am currently using?

You are correct about that not sounding right. The 1.5 meter length recommendation that is often seen for digital cables has no relevance whatsoever to cables conducting analog audio signals. In general, in the case of analog audio cables the shorter the better, if it makes any difference at all.

Also, regarding S/PDIF and AES/EBU digital cables, as you can see in some of the earlier posts in this thread the optimal length is dependent on a great many component and cable dependent variables, some of which are not usually specified (e.g., risetimes and falltimes of the output of the signal source). So 1.5 meters should be considered as having the best odds of being optimal for a digital cable (unless a very short length is practicable, such as 6 or 8 inches), but other lengths may be better in some cases, and there may be some cases where it won’t matter very much if at all.

Regards,
-- Al

Each end of a coaxial cable uses familiar RCA jacks, which are reliable and stay firmly connected.

Almarg wrote,

"The 1.5 meter length recommendation that is often seen for digital cables has no relevance whatsoever to cables conducting analog audio signals. In general, in the case of analog audio cables the shorter the better, if it makes any difference at all."

>>>>>That’s weird. Most high end cable manufacturers with good hearing like Bob Crump recommend 1.5 m as the optimum length for interconnects, maybe for speaker cables, too. I suspect the same is true for digital cables since they’re all conducting electromagnetic waves, so what’s the diff? Certainly the particular metal, copper or silver or gold infused silver, in a digital cable, like interconnects, is audible so why not the length? My personal favorite reason is that 1.5 m minimizes reflections. Al, I'm confident you will come up with a perfectly valid technical reason why length cannot possibly be an issue for analog cables, and why audiophiles must be imagining things.