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  • Pio2001
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Cables orientation
There is a french audiophile forum where someone foolishly asked if cables had an orientation.
You know, do they sound different if you switch the source side with the
destination side. http://www.homecinema-fr.com/forum/viewtopic.php?t=29744347

21 pages and 3 monthes later, the discussion went on possible measurments.
So I did some RMAA measurments between the two possible ways of plugging a
line in-line out coaxial cable. I wouldn't talk about it here if I hadn't got some
significantly different results, according to the orientation of the cable.

The cable is an RG179bu, silver plated copper, 75 Ohms. Hand soldered with 2%
silver alloy, on basic teflon / golden plugs.

Picture of the opened plug.

  • Last Edit: 12 September, 2004, 08:26:19 PM by Pio2001

  • Axon
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Cables orientation
Reply #1
Actually I've never really heard of burn-in affecting the "directionality" of cables - I hear directionality a lot more with respect to shielding. It's considered customary practice with some manufacturers to not connect the ground/shield on one connector, allegedly to reduce ground loop issues, as the ground loop can no longer travel along the shield. Amazingly, some people have found some theoretical basis for this design in some RF books (the references escape me now). However disconnecting the shield effectively turns it into a low-grade radio antenna, and the potential to drive EM noise back into either the source or the destination component (depending on the orientation) becomes much greater.

Are you sure that the shield is connected on both sides?

  • Axon
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Cables orientation
Reply #2
Also note that there is a noise effect, mostly prevalent on microphone cables hooked up to high-gain preamps, where simply moving the cable around produces a significant voltage due to changing dielectric values in the insulator. This usually isn't an issue for interconnects, but if you're getting accuracies down to literally parts per million for IMD, it could certainly be something that mucks with things. As a control test, I'd definitely try bending the cable by a significant amount.

  • Pio2001
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Cables orientation
Reply #3
Quote
Are you sure that the shield is connected on both sides?
[a href="index.php?act=findpost&pid=241320"][{POST_SNAPBACK}][/a]


Yes, sure. I just checked first with an ohm-meter (the cable is just coaxial), then visually, opening every plug.

Quote
simply moving the cable around produces a significant voltage due to changing dielectric values in the insulator.[a href="index.php?act=findpost&pid=241322"][{POST_SNAPBACK}][/a]


I know that moving the cable can produce a voltage. I've experienced it with a broked tape deck, moving the bare cable that used to lead to the playback head. I could actually hear my finger hit the cable in the line output ! I thought that it was the effect of the induced current caused by the acceleration of the cable in the earth magnetic field.

Quote
I'd definitely try bending the cable by a significant amount.
[a href="index.php?act=findpost&pid=241322"][{POST_SNAPBACK}][/a]


You mean to apply a physical permanent stress the dielectric ? I'll try this next time.

  • Omion
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Cables orientation
Reply #4
What's the audiophile's explanation of this phenomenon? That the electrons will get bored with one orientation, and desire a change?

It's probably on the French thread Pio linked to, but I know absolutely no French.
"We demand rigidly defined areas of doubt and uncertainty!" - Vroomfondel, H2G2

  • Pio2001
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Cables orientation
Reply #5
There is no technical audiophile explanation. Some talk about the direction in which the original copper threads are manufactured, but it doesn't fit with the burn-in hypothesis.
There are no blind tests that I know of either.
All that I've got is consistently different RMAA results when I unplug and replug my cable, everything else equal, and I'm trying to figure out why.

  • Yodule
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Cables orientation
Reply #6
Quote
Actually I've never really heard of burn-in affecting the "directionality" of cables - I hear directionality a lot more with respect to shielding. It's considered customary practice with some manufacturers to not connect the ground/shield on one connector, allegedly to reduce ground loop issues, as the ground loop can no longer travel along the shield. Amazingly, some people have found some theoretical basis for this design in some RF books (the references escape me now). However disconnecting the shield effectively turns it into a low-grade radio antenna, and the potential to drive EM noise back into either the source or the destination component (depending on the orientation) becomes much greater.

Are you sure that the shield is connected on both sides?
[{POST_SNAPBACK}][/a]


Normally, this kind of cable is shield + twisted pair : the shield is connected to one side only, one member of the twisted pair is the signal and the other member is the ground.

See for example [a href="http://www.jensen-transformers.com/as/as001.pdf]http://www.jensen-transformers.com/as/as001.pdf[/url]

  • Axon
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Reply #7
Quote
You mean to apply a physical permanent stress the dielectric ? I'll try this next time.
[a href="index.php?act=findpost&pid=241324"][{POST_SNAPBACK}][/a]

It doesn't need to be permanent - if the effect is there with just an orientation change, it should be OK to just put an extra twist or two in the cable before you plug it in.

  • Pio2001
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Cables orientation
Reply #8
Yes, I meant that it's the stress presence that is supposed to have an effect, not the stress modification, isn't it ?

  • Axon
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Reply #9
Quote
Yes, I meant that it's the stress presence that is supposed to have an effect, not the stress modification, isn't it ?
[a href="index.php?act=findpost&pid=241338"][{POST_SNAPBACK}][/a]

Actually I think the theoretical effect is supposed to be based on a change in stress, not merely a different stress. Potentially if you stress the cable a bit and leave it alone, some internal slippage may occur for the next several minutes/hours as the bends in the cable become slightly more permanent. However, if this really were the observed effect, it would manifest itself as a large change for the first test, with the effect decaying over time.

  • boojum
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Reply #10
Pio, I appreciate the exhaustive LycĂ©e influenced search for the truth.  But as a real skeptic I would like to see repeated tests of numerous cables before I believe that electrons pass one way through cuprous metals better than the other.   

Prends la Foy!
Nov schmoz kapop.

  • Pio2001
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Cables orientation
Reply #11
For the time being, the measurement don't show that the cable orientation is the cause of the difference. I must test further.
As for other cables, I let people try with theirs. This way not only other cables would be tested, but also in different circumstances.
In the french thread, someone suggested that if the orientation was the cause, it might come from a difference in the plugs : in in one orientation the source plugs are loose while the destination ones are very tight, and if in the opposite direction all plugs are just right, the latter orientation might give better results.

  • Garf
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Cables orientation
Reply #12
I skimmed rather briefly through this, but my question is, isn't it possible that such a miniscule difference is, for example, a temperature rise in one end/connector, for example because you held it in your hand.
From what I see the difference is so small with so many other potential variables, that we can't say anything from this.

And is it me or did the crosstalk "improve" by wiring it the wrong way around?
  • Last Edit: 13 September, 2004, 01:36:06 PM by Garf