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Cable directionality

Sue Pertwee-Tyr

Accuphase all the way down
On another thread, a comment was made about cable directionality.

That thread was already long enough and this particular thread drift was so far off-course that I thought it better to start a new one. The gist was that as the audio signal is AC, so the electrons don’t travel but merely wiggle back and forth, claims about cable directionality were nonsensical.

This is fair enough, at first glance, but claims about cable directionality persist so I picked the comment up to see where it took us. My query was that if the electrons don’t propagate through the conductor, how is the energy transferred? After a brief and jocular diversion into the participants’ knowledge of physics, a helpful reply was given.

I thought it might merit further discussion, hence the new thread.

The response went like this:

Well, start by asking yourself why an alternating current should be incapable of transferring energy. The alternating current and fluctuating voltage has a certain amount of electrical energy, and the amount of energy per unit time is power. In accordance with the 1st law of thermodynamics, this energy must go somewhere. If there was no loudspeaker in the circuit, and you effectively short circuited your power amp, this energy would be dissipated as heat and would blow up the amp. If you connect a loudspeaker, however, the drive unit will move in and out in a direction determined by the alternation of the current. Here, instead of dissipating the energy as heat, it is converted to kinetic energy in the voice coil and cone (plus a certain amount of heat); this is then transferred to air molecules... and so on.

Now, if the current did not alternate, and you passed DC through a speaker, it would not move in and out, could not convert the electrical energy to mechanical energy, would get hot and eventually die. Usually because the varnish on the voice coils melts.

So, essentially, the electric current can still do work (ie heat the wire, or move the drive unit) despite the electrons merely oscillating back and forth and not actually propagating anywhere. Unlike in the commonly-accepted the water analogy, where the water molecules would physically impact on whatever was at the end of the pipe and do the required work, it’s not moving electrons doing the shoving of the voice coil or whatever, but the electrical field which is generated by the acceleration of the electrons which creates the ability to do the work. The movement of the electrical field is independent of the movement of the electrons, indeed the speed of individual electrons is slow, a few millimetres per second, whereas the electric field which propagates as current, moves at a significant fraction of the speed of light.

(Where I get hazy is in considering how this electrical field is generated. Conventional theory says that the acceleration of a charged particle generates an electrical field, though it doesn’t usually say why. So the oscillation of an individual electron in an AC circuit means it is always in a state of acceleration, hence an electric field is generated and so-on. Quite how and why it propagates along the circuit, and in what direction, is less clear. My recollection of what my physics textbooks had to say about DC circuits is that this creation of the electrical field is rather glossed-over; in a DC circuit, the electrons do drift in the general direction of the current, and the number of electrons passing a point, per second, defines the current under, IIRC, Coulomb’s Law. But if the electrons are drifting, slowly, it isn’t entirely clear how the current propagates so quickly, nor yet how the field is generated as there appears to be no net acceleration of electrons).

That’s a digression and irrelevant for our purposes, however.

What is relevant is that in the AC signal, the individual electrons are busily shuttling back and forth within the conductor. The speed at which they do this is quite low, millimetres per second, and the frequency of the directional reversals is quite high in the case of an audio signal, so they clearly don’t go very far.

Conduction and resistance in a metal is determined by various factors, including cross-sectional area, temperature and the number of available electrons free to migrate, which varies with the material. Copper and silver are good, steel and aluminium are less good. It is also, however, determined by the microstructure within the material: grain boundaries, impurities and so-forth. This is all accepted physics. More grain boundaries or impurities leads to an increase in resistance (or reduction in conductance if you prefer). These are, AIUI, literal physical obstructions to the movement of the electrons.

A cable is made by drawing, or forcing, a billet of the metal through a small hole, so the cable emerges from the hole like toothpaste from a tube. If you’ve ever played with a Play Doh Fun Factory and extruded bits of smelly gunk through shaped formers, you’ll recognise the granular irregularities such a process creates. This granularity, being a physical consequence of the drawing process, reflects the direction in which the cable is drawn so, at a microscopic level, the granularity can be seen to indicate the direction in which the cable was drawn. This might therefore correlate to a difference in conductivity depending on whether the electrons are flowing along with the grain, or against the grain. In other words, if the electrons find it easier to cross a grain boundary in one half of their oscillation, but slightly harder to jump back across the grain boundary in the other direction, in the other half of their oscillation, this would lead to an asymmetry within the alternating signal.

To my mind, this gives rise to a possible explanation for why cables might be directional. It also explains why cryogenic treatment of cables, designed to reduce the number of grain boundaries, might be beneficial.

Any takers?
 
If the cable did end up being directional in the way you describe, wouldn't the AC signal be rectified?
 
A cable is made by drawing, or forcing, a billet of the metal through a small hole, so the cable emerges from the hole like toothpaste from a tube. If you’ve ever played with a Play Doh Fun Factory and extruded bits of smelly gunk through shaped formers, you’ll recognise the granular irregularities such a process creates. This granularity, being a physical consequence of the drawing process, reflects the direction in which the cable is drawn so, at a microscopic level, the granularity can be seen to indicate the direction in which the cable was drawn. This might therefore correlate to a difference in conductivity depending on whether the electrons are flowing along with the grain, or against the grain. In other words, if the electrons find it easier to cross a grain boundary in one half of their oscillation, but slightly harder to jump back across the grain boundary in the other direction, in the other half of their oscillation, this would lead to an asymmetry within the alternating signal.

To my mind, this gives rise to a possible explanation for why cables might be directional. It also explains why cryogenic treatment of cables, designed to reduce the number of grain boundaries, might be beneficial.

Any takers?

Sure.
What you've suggested has no effect whatsoever at audio frequencies on cables of normal construction and using the geometries we commonly see.

What you've done is suggest a semi-plausible explanation for an issue which does't exist for audio equipment. So in isolation what you suggest sounds reasonable enough, until you start looking at what happens to audio signals in cables and realise that the most basic twisted pair or simple coax can transfer audio signals perfectly given a modicum of care over termination characteristics.

If an audio cable displays any directional properties it's because the termination is different at each end, often because the screen connects at one end only, but you still have to demonstrate an audible difference.

To put this sort of argument and example into context, it mirrors that made by those who (rightly) assert that capacitors inside equipment can be microphonic under specific extreme conditions but then (wrongly) conclude that the smallest in-room source of vibration disrupts the performance of those capacitors.

Its all a bit Princess and the Pea :)
 
"Electricity is actually made up of extremely tiny particles called electrons, that you cannot see with the naked eye unless you have been drinking."

-- Dave Barry, "The Taming of the Screw"
 
c0eb2946_10117414.jpeg


(amusing, really).
 
The OP Sue asks some interesting questions and is obviously intelligent however there are very few scientists or at least that make themselves known on pfm.

I guess Sue didn't take 'O' Level Chemistry or if she did it wasn't well taught.

There are different types of chemical structure but metals have what is called metallic bonding. You'll never guess why! In the metallic bond 'free' electrons distribute themselves as a 'sea' of free electrons rather like a fluid travelling over the atoms. Thus the small amount of impurities have practically no effect on this pool of electrons but rather alter the Xtalline structure of the metal with various results. Thus there is no directional effect the sea is free to move under electrical and magnet influence i.e. the electromagnetic force. Simple cables carrying analogue signals can however be directional but that is to down with earthing arrangements.

When we get down to the Quantum level you'll find that the electron tends to 'smear' itself out. Take a simple Hydrogen atom with one electron orbiting a single proton. Calculations from Schrödinger's wave equation result in an electron 'cloud' distributed within the 's' shell. The cloud represents the probability of the electron being at that point. Think of a bicycle wheel. At rest you can see the spokes and can easily poke a straw between the gap in the spokes. Now spin the wheel fast and the spokes begin to look like a cloud. Can you now poke a straw through the gaps? There is a probability that you can if you are fast enough!

In the case of Hydrogen the electron in the s shell forms a sphere but other electrons in the p shell follow a dumbbell shape and those in the d shell a petal shape and so on not to mention things like sp3 hybridisation that gives rise to the very strong covalent bond between Carbon atoms. Think diamond the hardest element in the Universe and just pure Carbon if it is white.

The gist of the above is that electrons are not hard solid bits of stuff like a dry pea rather that they tend to smear out over quite large distances and have probabilities of being anywhere hence things like the Tunnelling effect which is like you placing a ball on one side of a wall and it will appear on the other side. Have you heard of Tunnel Diodes?

Sleep well.

DV
 
It was well taught, actually, but it was a long time ago and I've forgotten most of it, since I haven't used any of it since about 1982.

Thanks for the input, all. From what I remember on the previous thread, the concept of cable directionality was roundly ridiculed. What this thread seems to be saying is that it isn't impossible, merely unlikely, and there is at least one good reason for one form of cable directionality. Hardly deserving of ridicule, which is, kind of, what I suspected.
 
Sue - I suspect you are on right lines. The grain structure caused by drawing was the only effect I could think of. From a Classical or QM perspective I think this must be a strong contender for root cause.

Cheers

Richard
 
Before suggesting esoteric explanations perhaps it would be sensible to determine whether they are needed?

Orthogonally, it occurs that it would be straightforward to arrange for an audio interconnect to have electrons that always go forward (or back...). A marketing opportunity?

Paul
 
Sue I took Chemistry 'O' Level in '59 at 15. However I did teach it after I read Chemistry at Uni to 'O', 'A' and pass degree level and that was a very loooong time ago.

Some things have been burnt into my brain..........

Cheers and I guess once a teech always a .....

DV
 
Sue - I suspect you are on right lines. The grain structure caused by drawing was the only effect I could think of. From a Classical or QM perspective I think this must be a strong contender for root cause.

Cheers

Richard

This just reinforces my suspicion that either pfm members don't read posts or if they do they ignore them (for whatever reason) or if they don't understand they pretend that the posts never existed.

Please read my post as it is based on scientific fact. Why not Google some of it and try to prove me wrong rather than the usual circular arguments based on well rubbish really.

I posted some valuable stuff on the 'all amps sound the same' thread and you know what? Either no one took the time to read but if they did they either didn't understand or just ignored it and carried on regardless.

Cheers,

DV
 
This just reinforces my suspicion that either pfm members don't read posts or if they do they ignore them (for whatever reason) or if they don't understand they pretend that the posts never existed.

Please read my post as it is based on scientific fact. Why not Google some of it and try to prove me wrong rather than the usual circular arguments based on well rubbish really.

I posted some valuable stuff on the 'all amps sound the same' thread and you know what? Either no one took the time to read but if they did they either didn't understand or just ignored it and carried on regardless.

Cheers,

DV

I read your post, very interesting, and thanks for bothering! :)
 
Super Tweeter, they're saying its highly unlikely, not remotely that it is possible, except for the example Robert gives.
 
Several decades ago Floyd Toole of Canada's NRC did research on the claims of cable directionality.

I can't recall the details nor whether testing proved anything was statistically significant (that folks could reliably identify differences) but they did conclude something of interest going on beyond delusion. Their findings showed an unexpected resonance at 50 kHz when the cable direction was reversed.

For what it's worth.....

dave
 
Shurely if a cable allows electrons to flow more freely one way than another... they'll all get bunched up at one end?

Mull ;)
 
I've got a sure-fire solution to the whole problem and I'm willing to publish it at no charge just to help mankind considering the difficulty and importance of the matter:

Connect them observing recommended directionality as provided by the manufacturer (little arrows silkscreened on the insulation point in the direction of signal flow) and forget about it. Alternatively, connect some or all of them the wrong way 'round and pat yourself on the back that you're a Savvy Audiophile, pulled one over on The Man, or just generally smarter than all who do not do as You do.

If you don't like my advice, no problem. You got what you paid for.
 
Well I read about the way that K20 was supposed to go is based on the pointer in the logo. I finally saw the linn instruction leaflet which seemed to confirm that the E in the cable print goes at the amplifier end.
I saved a picture of that leaflet for future reference! I had been looking at a tiny triangle in the logo! Why they couldnt have just printed a big arrow, I dont know! :)

I could never hear a difference but felt a whole lot better knowing they were installed the way Linn intended. I could finally settle down and really listen to the music the way it was intended to be heard :D
 
That's my point, do you want to fret and worry about whether someone is pulling one over on you or do just want to get on with life? There are much bigger things to worry about than wire directionality.

Just hook it up like the manufacture recommends spending a tenth of a nanosecond (or less) considering that he may or may not know something you don't and then forget about it.
 


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