Interconnects, some have directional indicators, why?

Linn K20 / Naim Naca 4 speaker cables are directional due to a burn in process at the factory. If they are connected the other way around they will adapt to that and after a couple of weeks they will sound the same as before. There is a small audible difference.

If this is true also for other cables there is no actual inherit preferred direction in the cables as such but they should always be used in the same directional orientation.

According to van den Hul there is always a burn-in time required every time you move a cable since that upsets the contact between the individual strands. This makes sense and is logical.

So in general I would humbly suggest: Connect the shield at the source end if your using balanced or pseudo balanced interconnects and leave the cables alone. As soon as you move them and/or reverse the direction they will require a new burn-in period.

IMHO this is what people are experiencing as any talk about that crystalline structure in copper or amorphous structures in isolation should to some noticeable extent be inherently asymmetrical does not make any sense at all to me as a physicist. Atoms rearrange themselves all the time when acted upon by physical forces such as mechanical and/or electrical forces and will settle into their lowest possible energy state according to the laws of thermo dynamics after a while...

+danvignau The shield should be connected only at the source end so that any interference that is picked up by it is reverted to the source and not transferred to the input device. This lowers the susceptibility to interference from electromagnetic signals in the surrounding and therefore improves the signal integrity. One exception is microphones where the shield should be connected at both ends so that the casing of the mic is grounded. The same applies to turntables/tone arms and battery operated equipment if no separate ground connection is used.

The shield can thus be considered as an extension of the source units cabinet.

Can anyone please show the result of a scientifically performed double blind test using, let's say, 10 different manufacturers brand new 4' cables connected in the two different directions but otherwise identical and a panel of 10 listeners?

Then the cables should be "burnt-in" for a period of one month. the test repeated and then reversed and "burnt-in" again for the same period and a third test performed using the same identical set-up.

If the result is 2/3-1/3 or more in favor of one direction it would be a statistically significantly proven fact that inherent cable directionality is indeed relevant…

Personally I have never noticed any difference when turning a symmetrically terminated interconnect cable around but that is of course no proof that directionality do not indeed exist in some cases.

The current flow in unbalanced IC's is negligible. Input impedances are in the order of 5-100Kohms so it's basically only voltage changes that are relevant. Speaker cables are a different thing. When powering speakers current is the major factor (except for electrostatic loudspeakers).

Maxwells equations are of course still relevant in IC's but I must say that some people do make some very uneducated scientific remarks in this discussion.

There are basically the following factors:
1. Voltage
2. Current
3. Resistance
4. Capacitance
5. Inductance
6. Impurities in the material
7. Self induction

Factors that are all statistically the same for the whole length of a cable so where does inherent directionality fit in?

I'm not saying that inherent directionality does not exist but until someone presents a double blind test along the lines of the test suggested above I'm very sceptical about it's existence since it does not make any sense at all theoretically. Even if you turn the cable around the strands are still twisted the same way and every other factor also remains the same.

Could it be that the extrusion process would impart an inherit direction? Not very likely since atoms are 100% symmetrical and identical and all impurities in the material are distributed completely at random. The whole concept of inherent directionality in cables just does not make any sense to me as a scientist and if it really does exist it must be possible to scientifically explain the reasons for it.

Can someone please do THAT? Not just present a lot of hocus-pocus statements that have no scientific relevance at all...

+geoffkait Sure, extrusion does stretch the metal and as I wrote that may indeed be a factor that can explain inherent directionality. I can’t find any other… But you are wrong in the statement that all metals are crystalline. They are NOT! Metals are in in their basic state polycrystalline, that is they consist of many small crystals "grains" with amorphous atoms in between them. There is a significant difference but that is besides the main point of our discussion.

What kind of test would be more accurate than a double blind test? If such a test can’t detect any directionality with some kind of consistency it simply does not exist but is only a figment of illusion. If it does exist then we have encountered a manufacturing problem with regards to the quality of the cable in question!

If extrusion does cause significant irregularities in the metal structure I would humbly like to suggest to any serious manufacturer who detects such effects to simply make up their cables with half of the strands in one direction and the other half in the other in order to eliminate this problem all together as directionality only can be classified as a manufacturing defect. All it takes is respooling half of the bobins containing the individual strands and that is easily done...

Maybe it’s only because I have used well made cables in this respect when testing reversing them that I have not detected any audible differences with regards to their orientation. That may, of course, be the case! No doubt about that...

I’m, as I stated, not saying that inherent directionality in cables does not exist. I’m just trying to resolve the problem that many obviously have experienced when using poorly designed cables. In a well made cable any sort of directionality should NOT be detectable!

And, yes, I am a physicist as well as a professional sound engineer and techie so I’m only concerned with scientifically relevant issues…

And, yes, your comment make sense to me! :-)
I’m just trying to lift the discussion to a scientific level… :-)
I have just not simply yet encountered any such crappy cables...