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Optimal length(s) of a digital aes/bsu cable

I have an option of a high end cable (0.6m) as a digital interconnect between a Berkeley USB and Reference DAC. I’d rather have a short cable practically speaking as the boxes sit next the one another but I also want to maximize sound quality (of course.)
i have read in agon that I should go with less than 1ft or >1.5m. That was with spdif but what about aes/bsu? Does that have a different dynamic, being balanced and all?
Thanks!
128x128johnmc67
jjss49's avatar
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jjss49
6,612 posts
 
yes, to be a bit more specific - 1.25 up to 2 m - so 1.5 m is a safe number

digital reflections can occur (at least in theory) at 1 m length
richtruss
163 posts
 
There’s a lot of good theory on this subject. In practice though, how cable length effects sound quality is difficult to hear. We manufacture cables and have tried various lengths of the same build. For our ENO Digital Cable Cu and Ag, two cables built identically, one at 1M and one at 1.5M sound identical. If you start talking about much longer distances I’m sure things change.
johnmc67's avatar
johnmc67 OP
5 posts
 
Thanks for the input fellas - all very helpful! BTW - the link from rodman9x is an excellent piece. 
kijanki's avatar
kijanki
4,428 posts
 
It depends on the output transition time .  Without going into details, it is roughly transition time divided by 20.  For typical 25ns transition it has to be longer than 1.25m.  The problem is that transition time is unknown (and almost impossible to measure) and can vary from 5ns to 50ns.  The main concern is that refection from the end of the cable will distort transition at exactly threshold point.
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