Yes, Ohm's Law is not basic. That is, it is not an essential property of the Universe, unlike (for example) Kirchoff's Current Law which is an expression of charge conservation. However, Ohm's Law seems to be a very good approximation of the behaviour of many conductors, for reasons which we understand, so it can be confidently used in much electronics. In the context of skin effect all we require is that current density = conductance x E field, which is an expression of Ohm's Law.academia50 said:
Another misrepresentation.
DF96 and I have been at odds here more than we have been on the same page. that however, does not mean I "don't care who he is". I judge him entirely on the technical content of his posts.
His posts here were correct, spot on.
I do not advocate for him, he can do that well enough on his own, and certainly does.
Speaking of advocate, you are certainly trying your best with your buddy Alex..
Should I also fall to your level and accuse you of being his lawyer???
Nope.
jn
Linearity, superposition in the skin effect can be mind boggling.
No doubt Maxwell laws are linear. The Nabla operator is linear, that is the proof, at least for me.
BTW, I give tribute to William Rowan Hamilton, an Irish mathematician that had developped the maths ready for use, unaware of it's future use, maths ready before James Clerk Maxwell ( Scottish ) used it.
Generally matter is not linear. Conductors and dielectrics are idealized linear materials.
A copper wire is usually considered a conductor, hence linear, but who knows at some accuracy there might be non linearities. So far none is known at the accuracy scale of audio electronics.
What is mind boggling in the skin effect is when thinking about two AC currents at different frequencies.
Intuitively it seems they fight each other at sharing the depth in the wire.
Actually each one acts in the wire as if the other did not exist.
Hopefully, this is true, otherwise we would have intermodulation in the wires. No electronician has ever reported intermodulation in normal wires. I bet one can get it coating the copper with magnetic materials know to be not so good linear materials.
No doubt Maxwell laws are linear. The Nabla operator is linear, that is the proof, at least for me.
BTW, I give tribute to William Rowan Hamilton, an Irish mathematician that had developped the maths ready for use, unaware of it's future use, maths ready before James Clerk Maxwell ( Scottish ) used it.
Generally matter is not linear. Conductors and dielectrics are idealized linear materials.
A copper wire is usually considered a conductor, hence linear, but who knows at some accuracy there might be non linearities. So far none is known at the accuracy scale of audio electronics.
What is mind boggling in the skin effect is when thinking about two AC currents at different frequencies.
Intuitively it seems they fight each other at sharing the depth in the wire.
Actually each one acts in the wire as if the other did not exist.
Hopefully, this is true, otherwise we would have intermodulation in the wires. No electronician has ever reported intermodulation in normal wires. I bet one can get it coating the copper with magnetic materials know to be not so good linear materials.
Friend, you are contradicting yourself about your intentions, and you prejudge your neighbor too much ... I am not interested in childish alliances with anyone here.
I have no greater interest in the forum than to contribute what I can, entertain myself, and learn, although I am very clear that I will never know everything. I'm not interested, I learned a long time ago that having a high IQ is not synonymous with winning the sky. More hell.
Instead I firmly believe in the emotional coefficient to go through this world suffering as little as possible.
Review all your posts in this thread and you will see that you are very convinced that you are a superior being, my congratulations for it.
I would recommend this book, I think you would like it because you would learn that there are many things in our minds beyond the frontier of purely technical knowledge, which is cold, calculating and insane in many cases, but ask the manufacturers of armaments ..
Open the link without fear, the computer viruses are not transmitted with the only echo of opening a link, if you do not know, although I think you would not admit it even if it were like this .....
Be happy.
Regards
Inteligencia Emocional, resumen del libro de Daniel Goleman
There is only one current flowing in the wire. As current is a rate of electrons flowing per time unit, cannot be some electrons "running" at one rhythm and others to another rhythm. I know that velocities are mean values, actually some go faster than others, but all them create only one current in the wire.
Right.
It is fun to imagine electrons chatting.
_Hey who are you running for 1KHz or 2KHz.
_Do you want to intermodulate with me.
_Nagh, you dirty.
No, they can't. (independent rhythm's that is)
If you think of the wire cross section as that wiki page depicted, note the currents in the conductor that are circulating from outer to inner as a torus.
Those currents are internal local currents that are created by the rate of change of magnetic field in the wire generated by the axial currents. When the total axial current is rising very fast, those toroidal currents will subtract in the center, add at the edge. The overall current profile is supressed at the core, enhanced at the edge, and gives the current profile we identify as skinning.
At any point in time, the current profile is dependent on how fast it changes, and what direction it is changing to with respect to the total current.
While it's easier to think of this as a frequency dependent thing, it is actually caused by the rate of change of the current. But we all, me included, think of it mainly as a frequency dependence... as going all derivative and integration of the cross section, and bessels... way too complex. Gives me a headache even typing about it.
Music will have constantly varying rate of change of current, and the wire will react to that specifically. The wire does not separate the currents based on frequency, but the depth of penetration will certainly vary with current slew rate.
jn
Edit: Earlier on, it was mentioned that longline cables used mu metal to reduce distortion. Early on back in the day, it was realized that L,C,R, and G could be manipulated such that all audio (voice) frequencies would travel at the same velocity in transmission lines. Without that understanding, voice would distort in the tens of kilometers distance.
Replacing the wire insulation with mag tape is an interesting and perhaps novel idea. However, as a mimic to longline mu metal use, it totally missed the boat. In longline, they used T-line theory, so calculated exactly what they needed in terms of L, C, R, and G.
I would listen should the OP provide the equations, the theory, the test methodology, and the test results to back his claims. Since he has stated there are none, what do we do with explanations that have no basis in physics other than "trust me I hear a difference"?
ps...how many people nowadays click on links when the purveyor says "don't worry, the computer viruses don't...."
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I just use zip cable.
Dowell curves could be applied the the inductors of the crossover, but for a zip pair, there is no major field enhancement like what results in a many turn inductor.
John
For the benefit of others, that is what we argued about. However, I don't think either of us has plans to resurrect that argument in this thread.jneutron said:
Putting some high permeability material around a long-distance telephone wire to raise inductance and hence reduce dispersion was based on physics. It worked. Other methods of raising inductance were also used; they worked too. Not really comparable with wrapping a magnetic material around a wire in order to allegedly reduce skin effect; even if it did reduce skin effect (which I doubt) it would not benefit the audio because the audio in a piece of wire is only negligibly affected by skin effect. If skin effect is significant then you need to use a different wire.
Skin effect is an example of something which snake oil merchants often do: mention a real physical effect, blow it up out of all proportion and falsely claim that it noticeably affects audio, then offer a 'solution' which in most cases does nothing useful at all and in a few cases makes a small difference which is well below the threshold of sensitivity of any human from this planet.
I agree with that, and in fact it is what is used for calculations of special cables for audio.
Although some might see conspiracy to be compatriots Osvaldo and I, do not do it. And I find it interesting and I accept his suggestion that we should not mess up the thread.
Yes, it is a very remanido subject, but if it continues summoning readers, it means that it concerns us all, who does not have a pair of cables attached to its amplifier and speakers ?
So it would be good to change the focus of the tape a little as a coating and talk for example of the twisted cables of telephone or network pairs.
I always wanted to build one, but, "the one that covers a lot, little squeezes" ...
Has someone made it and what are your opinions and / or measurements? Are there audible differences for ordinary mortals (golden ears to abstain) with conventional electricity cables of adequate thickness?
You should have used the irony emoticon....
There actually needs to be one.
jn
academia...to me, common flags do not mean conspiracy..
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The special cable that we made here was promoted as you will have seen in my previous post in specialized magazines. I personally visited all our clients to convince them of the benefits of it. Crossing my fingers so they would not tell me:
Ok, let's hear how much truth there is in what you affirm!
So after failing many times, I thought I had to modify something in my arguments, and then I was carrying a balanced 300-ohm TV cable coil 100 meters long.
It connected in a channel the special cable and in the other the analog cable TV cable, remember it?
The sale was assured.
I hope you and all know how to have some humor and do not make me expel the inveterate technocrats, it's just a joke !
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I don't use emojis, I like much more the old DOS-TXT style, like
Well, my joke also went down in flames, there is no irony emoji...
But I missed your joke...sorry bout that.
jn
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