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Jitter and 75ohm cable length

I have read a number of papers on how cable length plays a role in Jitter between transport and DAC. After all of the dust settled I arrived at no sound conclusion, on paper, so I decided to use the ears of my 17 year old budding Audiophile to settle this by LISTENING! My transport is a Wadia 171i (WAV/LossLess files)and my DAC is a Cambridge AZURE 840C. I had three cables in my test, my 1M Kimber D-60 illuminations, a 3' HAVE/Canare and a 6' HAVE/Canare. All three cables sounded good, but in the end the victory landed on the 3' HAVE/Canare by a fair margin followed by the Kimber and last the 6'HAVE/Canare. In my readings I came across a number of articles saying you should use at least 1.5M of cable to reduce reflections in the cable so as to not harm the clock signal, yet an RF engineer said this was a bunch of "Bunk" and 1M would be better, in fact he said the shorter the better. So, forgive my verbosity, what are your thoughts and experience in this area? My 3' $25 HAVE/Canare beat up my $390 Kimber, I believe due to proper honest 75ohm terminations vs standard RCA connectors, and as far as length goes, at least in my system, 3' was by far the best. Thanks!
Rpg
rpg
rpg OP
126 posts
 
Can someone here give me a hand with the math and it's implications with respect to two different cable lengths from the exact same manufacturer. Much of the math in this forum is in meters, the typical standard. One of my cables is 3' in length and the other 6' in length and strangely they sound different. Specifically, the 3' cable sounds very fast slightly bright (or hyper detailed) where the 6' cable sounds a bit warmer, maybe slightly rolling off the top, or maybe just cleaner at the top. I've talked about these cables earlier choosing the 3' cable as the champ, but now I'm finding the 6' cable easier to listen to. How can this be explained and may the 6' rout look better on paper and on the ears - thanks!
Rpg
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almarg
9,670 posts
 
Rpg, 1 meter is about 39.37 inches. And of course 12 inches = 1 foot.

Therefore 3' is about (12 x 3)/39.37 = 0.91 meters, which DOES NOT conform to the length recommendation.

6' is about (12 x 6)/39.37 = 1.83 meters, which DOES conform to the length recommendation.
I've talked about these cables earlier choosing the 3' cable as the champ, but now I'm finding the 6' cable easier to listen to. How can this be explained and may the 6' rout look better on paper and on the ears.
Chances are that less jitter is present with the 6' length, but as explained earlier that is not a certainty. Also, as explained in the section entitled "Jitter Correlation to Audibility" in the Steve Nugent paper I linked to a few posts above, depending on its spectral (frequency) characteristics jitter can sometimes be euphonic in character, and/or mask or compensate for inaccuracies elsewhere in the system.

So the bottom line obviously is to try to decide based on listening, but I would say that if the cables sound different but neither can be determined with confidence to be "better," chances are it would be best to go with the longer one.

Regards,
-- Al
rpg OP
126 posts
 
Al, thanks, I appreciate your work in helping me understand this. I think in the end, as I may have mentioned, the 6' cable is easier on the ears. With this cable manufacturer, I can order any length, is there an "ideal" length, or are there too many system dependencies to determine this?

Again,
Thanks!
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almarg
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With this cable manufacturer, I can order any length, is there an "ideal" length, or are there too many system dependencies to determine this?
Summarizing all that has been said, I would put it that a length of 1.5 meters (which is virtually the same as 5 feet, to within less than an inch), stands a better chance of being ideal than any other length. But as have been cited there are many system dependencies and cable type dependencies which conceivably could result in other lengths being better in some cases.

In this case, if you decide that the 6' cable you have is preferable to the 3' cable, my suspicion is that changing the 6' cable to a 5' cable of the same type would be unlikely to make a significant difference.

Regards,
-- Al
rpg OP
126 posts
 
Al, thank you very much - most appreciated!
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