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In Reply to: RE: RE Is stranded cable directional? posted by unclestu on February 27, 2014 at 17:09:25
Here is what Belden has to say about directional cable:
Directionality, or the idea that electricity flows better in one direction through a cable than the other, is a common concept among certain self-identified audiophiles. Belden did a double-blind test for cable directionality in conjunction with an audiophile magazine. The end result was perfectly random. Belden is still happy to manufacture and sell directional cables to enthusiasts. They make up a long length of cable, cut it in segments, identify the ends of the segments so they know how it came off the spool (length A->B, length B->C, length C->D, etc), and then let the customer identify by careful listening which direction is "better". Over thousands of cables sold, the chosen "best" signal flow is random, for segments cut from the same spool!
Follow Ups:
What was the test procedure? Who were the test subjects? When a magazine like Stereophile has reviewers who can not hear the mixed phase in many of the speakers they review, you think I would believe they can hear directionality differences?
Plus, They really and actually tested thousands of samples?
I somehow doubt that figure.
I have tested tens of samples over many spools being a dealer. I can consistently hear differences. For many, the differences are rather small, sometimes insignificant for some, but I can still hear them. For me, the difference is important enough to always code the ends.
and of course YMMV
You, as well as everybody else, hear what you subconsciously believe you should hear unless you do a double blind test. Unless you've done that anything you believe you heard is no more than an anecdote.
On another note: Logically if AC signal cables were in any way directional the signal, when reaching its destination, would have to be grossly distorted.
On another note: Logically if AC signal cables were in any way directional the signal, when reaching its destination, would have to be grossly distorted.
Why?
To be directional the cables impedance/resistance would have to be greater in one direction than the other.
Or if you think in terms of vibrating electrons imagine a cable running from left to right.
The electrons would be freely moving to say the right but would have to be restricted in their movement to the left or vice versa.
An extreme case would be a diode: Near zero impedance in one direction, near infinite impedance in the other. If you feed an AC signal through it the result is nothing like the original waveform since half of it would be completely missing. A truly directional cable would have to have a similar although lesser effect resulting in gross distortion.
You wrote,
"To be directional the cables impedance/resistance would have to be greater in one direction than the other."
It is. Just like fuses.
if the impedance is different in the two directions, then this can be measured. Measurements are not the end, they are a means to the end, which is good sound. Where measurements are available they can be quick and reliable. Listening tests tend to be unreliable and costly. If one is trying to improve the sound of a product (or a system) working by listening tests will be slow and costly. If effective measurements are available then much of the journey can be done quickly, with fewer expensive listening tests required.
Tony Lauck
"Diversity is the law of nature; no two entities in this universe are uniform." - P.R. Sarkar
You wrote,"if the impedance is different in the two directions, then this can be measured."
I never said or even suggested that it couldn't be measured. Of course, nobody actually does measure it.
You also wrote,
"Measurements are not the end, they are a means to the end, which is good sound."
OK, if you say so. Are you volunteering? Measurements of what, that is the question. In this day and age, there are a great number of things that cannot be measured, or at least one would have difficulty coming up with a measurement strategy. You know what I'm talking about.
You also wrote,
"Where measurements are available they can be quick and reliable. Listening tests tend to be unreliable and costly."
Really? I would think the opposite. Unless you already have the measuring equipment. Besides, you still have the problem with WA Quantum Chips, clocks, rainbow foil and all those other things that go bump in the night.
You also wrote,
"If one is trying to improve the sound of a product (or a system) working by listening tests will be slow and costly."
I actually don't think that's true. Not slow, not costly.
You also wrote,
"If effective measurements are available then much of the journey can be done quickly, with fewer expensive listening tests required."
How do you effectively measure a lot of the new fangled things that have popped up in the last twenty years? All the quantum stuff. All the PWB stuff. Let alone all the CD fluids, room tuning widgets, all the RFI/EMI doo dads, even vibration control stuff. Much easier to conduct listening tests.
Edits: 03/01/14 03/01/14
Stu: "For many, the differences are rather small, sometimes insignificant for some, but I can still hear them. For me, the difference is important enough to always code the ends."
You: "Logically if AC signal cables were in any way directional the signal, when reaching its destination, would have to be grossly distorted."
I'd say your "logic" has a few bugs in it. Stu has identified directionality as a subtle effect. You claim that if it isn't gross it's nonexistent. See the disconnect?
I've heard it and at least in that instance it was subtle, but like Stu I too thought it worth controlling-for as it was easy and free since I was building my own cables anyway. It was subtle enough that I just assumed that it would be tough to measure so I really didn't try. It was most evident in the sound of soprano sibilences.
Might be fun to look at further one day. I still have most of the same stuff around.
Rick
Vocal waveforms tend to be asymmetrical. I suspect if you carried on you would be able to show up the effect using a suitable test waveform. I would start by looking at amplitude spectrum plots.
Until you can get repeatably different measurements it won't be possible to investigate further as to more specific causes, e.g. whether directionality is in the cable itself, in the connectors, or in the results of the physical termination processes.
Fun for a rainy day?
Tony Lauck
"Diversity is the law of nature; no two entities in this universe are uniform." - P.R. Sarkar
"Fun for a rainy day?"
Could be. No shortage of pursuable stuff in home audio but we get quite a few rainy days...
Rick
In my system directionality is not subtle. Both for interconnects and fuse. Very pronounced.
"In my system directionality is not subtle. Both for interconnects and fuse. Very pronounced."
Interesting. I didn't really test across systems. Have you tried to sort it out at all?
Rick
Not sure what you are referring to. Please elucidate.
"In my system directionality is not subtle. Both for interconnects and fuse. Very pronounced."
That should make it easier to "sort out", i.e. figure out the mechanism, than it would be if the effect were more subtle. Usually the grosser the effect the more likely it's readily measurable...
Rick
We already know what the mechanism is. And we've known it for twenty five years. Hel-loo!
"We already know what the mechanism is. And we've known it for twenty five years. Hel-loo!"
Gosh... That's wonderful. Help an old guy out, what was it again? I can't wait to pour over the supporting data and all...
R.
Roughly a couple of years ago I played around with a 75 ohm RG6 copper solid core quad shield coax cable to see if it was directional. I did not have any true 75 ohm RCA plugs. I just used a pair of Vampire RCA plugs I had. For the length of the cable I used the accepted 1.5 meter length. I think I made it just a tad longer.I used the digital out on my ARCAM Alpha 9 CDP connected to a Cambridge DAC Magic.
I first powered up my system and let it warm up for about 30 minutes. I picked CDs I was familiar with. For critical listening I like to use CDs with female vocals and parts with piano solos.
Just going from memory I played Diana Krall, "The Girl in the Other Room" and "Love Scenes". I also like to use Jenifer Warnes, "The Hunter" and "Famous Blue Raincoat".I did not pre burn in the cable. I did not want any settle in time on the cable.
The test.
I sat down for a listen.
I picked a track and listened only to a particular part over and over 2 or 3 times to train my ears to what I was listening to.
I then flipped the cable end to end and listened to the same part of the same track again.
Long story short the differences were not subtle.It was quite easy to pick the direction that sounded best to me on my system.
Once I found the direction that sounded best to my ears I then took a fine point sharpie pen and put a small dot on the cable end that connected to the DAC. I wanted it to be hard to see.
Next listening test was to listen to an entire track of a CD. Time after time I could pick/identify the direction that sounded best to my ears.
Next test, I took the cable down to an audio dealer I know quite well.
I talked to a salesmen I have known for many, many, years and asked him to listen to the cable. I did not say anything to him that might influence his listening experience. I just told him I had made the cable from a piece of RG 6 coax cable I had.
Long story short he picked out the direction that sounded best to his ears 100% of the time. The direction he liked best was the same as I had picked.
I should note this guy is not really into cables. He couldn't believe the coax cable could be directional.Before I left the Store I looked at a 2 meter Tributary digital cable hanging on a wall display. That’s right I said Tributary. Supposedly tributary’s best digital cable. I asked the salesman is the cable directional. He replied no. I asked him are your sure? He looked it up in a Tributary book and replied nope the cable is not directional. I said let me take it home for a week or two for an audition.
Well guess what? The digital coax cable is directional. And the center conductor is solid core copper. Again I marked the end of the cable that sounded best to my ears that connected to the DAC for a reference. I kept the cable for at least 2 weeks.
Back to the Dealer's store I went.
Long story short the salesman picked the correct direction 100% every time.Scientific test? No....
.
.
.
.
.
The revelation that digital interconnects and their direction can introduce large differences in measured jitter was quite a shock. The differences heard between digital interconnects—and in their directionality—have now been substantiated by measurement.
http://www.stereophile.com/content/transport-delight-cd-transport-jitter-page-9
Edits: 03/01/14 03/01/14 03/01/14 03/01/14
"Scientific test? No...."
Well...I don't agree, I think it was quite scientific and I'd say the odds are long that your coax cable's direction audibly affects the system performance. It sounds like you made a reasonable effort to avoid bias and had no investment in which way was best, if either.
And you know, I don't remember if I ever tried reversing mine. I've got one link in particular that I definitely want to run a test on. It just never occurred to me.
There are all sorts of reasons for testing things, what sort of cook doesn't taste the sauce? It's the unexpected correlations that spice things up. It's one thing if adding salt to the stew affects it's flavor, quite another if doing so makes the screen door quit squeaking. It usually pays to be a good observer and that includes not wontedly ignoring things that weren't expected.
Rick
Rick,Did you read this?
The revelation that digital interconnects and their direction can introduce large differences in measured jitter was quite a shock. The differences heard between digital interconnects—and in their directionality—have now been substantiated by measurement.
http://www.stereophile.com/content/transport-delight-cd-transport-jitter-page-9
Quote from Stereophile article.
Conclusions
There is now no question that jitter in CD transports and digital interfaces affects digital audio sound quality. Not only do different transports and interfaces sound different, they produce varying amounts of jitter and have their own "jitter signatures," seen in the jitter's spectral distribution.Moreover, we can see that transport jitter goes right through the digital processor's input receiver (even the Crystal CS8412) and affects the amount of jitter at the DAC's word clock—the point where jitter makes an audible difference. If the word-clock timing is different, the sound will be different.
The revelation that digital interconnects and their direction can introduce large differences in measured jitter was quite a shock. The differences heard between digital interconnects—and in their directionality—have now been substantiated by measurement.
Although the CD-transport measurements presented here are fascinating, it is impossible to draw conclusions about how a transport will sound solely by looking at its jitter measurements. Based on the measurements and listening impressions of the Audio Alchemy DTI, we can confidently conclude that the jitter differences the DTI imposes on both high- and low-jitter sources are easily audible, and that lower jitter always correlates to better sound. But when examining the jitter performance of other transports, a direct correlation is less clear.
Edits: 03/02/14
"Did you read this?"
Probably... back when. I shall, again?
Thanks Jim
Rick
You were probably napping when it was discussed. A search of the archives might turn up something, who knows?
Ah, the AES connection. Now, that makes sense!
:-)
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