I thought @scottjoplin had a very nice cable thread.
https://www.diyaudio.com/community/threads/speaker-cable.329395/
Not every cable thread dissolves into endless flame wars.
As I said, the exponential equation used to calculate skin depth is derived from the planar wave penetration depth. It is not accurate for a circular conductor transporting current. To properly calculate it for a round current carrying conductor, you have to use bessels.
It is not "our current understanding" of skin effect which is flawed. It is the use of an approximation formula without consideration of where the formula is useful and accurate enough, and where it is not. In the audio world, the approximation formula is typically bandied about without knowledge.
You really want to go nuts? Calculate the skin depth for a superconductor with infinite conductivity. Turns out, the conductor does skin, but it simply populates the wire from the outside in at the critical current density of the conductor. if the critical current is 1000 amps per square mm, 1000 amps of current will be carried on the outer 1mm square area. When the cross sectional area of the wire is filled up, then the wire will quench. When I make a magnet with superconductors, the currents will distribute the exact same way a normal conductor would, only using proximity effect.
Hawksford's paper had several fatal flaws in it. When he did his experiments, he actually used steel conductors, not copper wires. So the permeability of the wires blew out the inductance of the wire pair and gave incorrect results.
John
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No problem.
As the meter is driving the load, it is looking for the in phase and out of phase current the load draws. It simply assigns all in phase current to the resistive component of the inductor, 90 degrees out is the reactive component. The reactive component returns energy to the meter, the dissipative component is lost into the tested device.
Eddy current dissipation occurs during the slew of the signal, as eddy currents fight the rate of change of the magnetic field within the conductor. Resistive losses are a consequence of the magnitude of the current, whereas eddy losses are a consequence of the rate of change of the current. The meter does not worry about where the dissipation occurs in the cycle, just that it does. So it cannot report how much of the loss is resistive vs eddy.
Eddy losses are the highest during the zero crossing of the magnetic field, and they are dependent on the absolute value of the rate of change, which peaks twice per cycle.
Just had this happen at work, they were getting beam modulation at 700hz and 900 hz together. They started measuring an aluminum beam chamber for those two frequencies because I informed them that that frequency ratio matches exactly the ratio of transverse to extensional velocity of sound in aluminum, so matches possible resonances (modes) of the beam chamber.
They did not see 700 nor 900 hz vibration, for very good reason. movement of the aluminum in the 4-5 tesla field modulates the field at twice the frequency, so they should have been looking for 350 and 450 hz.
john
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This is like if someone asks if wires are sexual, and the answer is that they are bisexual.
Audio cables have no sexuality*, and they are not directional.
* Plugs and connectors may be a different story 🙂
Skin effect is a basic principle. Using an approximation solution which is in error for a specific case means the basic principle was not correctly taught.
The stepper motor microstepping vs torque is a basic principle. For a masters prepared engineer to come out of the program with an erroneous understanding of that means the basic principle was not correctly taught.
I limited my examples to simple, basic principle things that should have been taught in undergraduate programs.
Complex principles are outside the scope of an audio forum. For example, a Bode plot of a system response is easy to understand, but not when the bode plot changes as a consequence of the acceleration or velocity of the system.
John
Edit: to me, the issue is NOT that any principles were taught incorrectly. It is that it was never questioned.
All would be served well to read Asimov's novella "Profession".
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So many conditionals and disclaimers that really .... what´s the point of mentioning at all?
DIYPhilosophyForum . com might thrive on such vague statements, in principle they do NOT rely on experiment at all, now on any Technically based one ... we ask boring Physics for proof one way or the other.
My suggestion is that you measure the frequency response in the experiment with a spectrum analyzer and not with your ear/brain subjective mechanism.
If you do that you will see no difference whatsoever when the cable is reversed. Therefore, there will be no audible difference when the cable is used to play music regardless of which way it is positioned.
End of story. No further comments are necessary or should be expected from me.
And cable directivity really is the main subject of this thread as I specifically stated in the title of the thread.
I'm glad to see it get back on track.
Oh, but do spectrum analyzers know anything about Musicality?
Or soundstage?
Or microgranularity?
Or black noise?
kkkkkkkk , just joking.
Or soundstage?
Or microgranularity?
Or black noise?
kkkkkkkk , just joking.
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Oddly enough, there are no measurement tools capable of measuring soundstage.
Black noise...well, interestingly, I was involved in the initial design of a liquid argon detector with IIRC, 14 megavolts of gradient field. I suspect it would be capable of finding black noise if it exists.... Sadly, the physicists were unaware of the incredible advances in speaker wire technology, so they had to flounder and flail with bog standard world class physics stuff and nobel prize guys..if only they knew..
john
Ten Hours of Black Noise
https://en.wikipedia.org/wiki/Black_Noise
https://faroutmagazine.co.uk/bowie-burroughs-and-the-black-noise-bomb/
https://www.blacknoise.com/site/en/home.php
YEs, I do agree on this! We have ways to create positional audio (i.e. create a sound that appears to come from certain direction/position). We could hear it as well, its very easy to pintpoint location of the sound.
However, we don't have a way to measure this other than hearing it ourselves.
That's the other way around. The idea that there is a sound stage or depth is all inside our head, literally. Because in the real world there's only two boxes that emit sound (for stereo that is). It is a construct in our mind that there would be a singer bertween those boxes, there definitely isn't, otherwise we would see him/her (and would have to pay them ;-).
Jan
Jan
I agree it is inside our head. Over time we have learned how to manipulate the channel information to alter how we perceive location of the sounds.
The question has always been what aspects of the system are capable of disturbing the perception. And unfortunately, we do not have the test instruments capable of substituting for our perception.
John
LOL! ... really enjoyed reading the entire thread as I always do with this type of subject.
You'll nearly always get somebody with a financial interest in exotic cables or other "believers" who have bought into the "club" repeatedly asking for proof.
IMO the reason this is done on technical forums like this is to add credibility to the B.S. and help to convince technophobes that they should be spending more .e.g. when they surf about they find these seemingly inconclusive arguments everywhere so find it easier to literally "buy" the hype ... then they will defo hear the difference ... 🤣
As a 35 year veteran sound engineer I have done a fair amount of critical listening and A/B tests need to be done instantaneously with silent switching & the ability to switch back and forth... even a few seconds gap can skew subjective listening.
I'm not surprised "punters" are convinced they hear a difference after changing cable direction though ... with a long time gap and maybe the speakers being moved slightly as they change cables then sitting in a completely different position to listen more intently now for the difference that they are looking for. I don't see room acoustics mentioned often in these discussions & moving your head position or listening angle even a tiny amount can make a very real subjective difference sometimes but it has nothing to do with "directional" cables 😆🤣😆🤣😆
Always find these discussions highly entertaining .... 😎
You'll nearly always get somebody with a financial interest in exotic cables or other "believers" who have bought into the "club" repeatedly asking for proof.
IMO the reason this is done on technical forums like this is to add credibility to the B.S. and help to convince technophobes that they should be spending more .e.g. when they surf about they find these seemingly inconclusive arguments everywhere so find it easier to literally "buy" the hype ... then they will defo hear the difference ... 🤣
As a 35 year veteran sound engineer I have done a fair amount of critical listening and A/B tests need to be done instantaneously with silent switching & the ability to switch back and forth... even a few seconds gap can skew subjective listening.
I'm not surprised "punters" are convinced they hear a difference after changing cable direction though ... with a long time gap and maybe the speakers being moved slightly as they change cables then sitting in a completely different position to listen more intently now for the difference that they are looking for. I don't see room acoustics mentioned often in these discussions & moving your head position or listening angle even a tiny amount can make a very real subjective difference sometimes but it has nothing to do with "directional" cables 😆🤣😆🤣😆
Always find these discussions highly entertaining .... 😎
I have measured cables with different response in different directions. Its a manufacturing defect but can be hard to avoid, the dimensions are different over the length of the cable. However this is in the multiMegaHertz and GigaHertz range. As for audio, if you terminate the cable with a network or a resistor it makes a difference to the amp which end of the cable the termination is connected (and can be catastrophic at the wrong end). Jneutron has one of the best understandings of audio frequency signals over cables I have seen or read. And what he describes matches what the complex field solvers show like Comsol. These are complex situations that go beyond Ohm's law to Maxwell's equations. Fortunately the software does a pretty good job of processing all the different pieces.
And how does any of that relate to Audio, which is the Forum subject?
Waste of time.