Simple question, or is it...

Electric current in the cable is a flow of electric charge.  Exactly the same amount of electric charge that leaves the source comes back to it.  Energy is delivered from source to load by electromagnetic field in between wires.  It is called Poynting field and direction of this electromagnetic wave can be determined by Poynting vector.  Presence of the load creates voltage drop - an electric field between wires.  Current in the wire creates circular magnetic field around it.  These electric and magnetic fields are perpendicular.  If you imagine them as X-Y axis then Poynting vector will be perpendicular to them as "Z" axis.  This vector points always in the same direction, (from source to load) even with ac current, since both electric and magnetic fields change direction at the same time.  In the coax cable, that was mentioned, whole energy (electromagnetic field) flows inside thru dielectric between wire and the shield.

OK but when you aren't using coax cable the energy doesn't flow through the dielectric? 

When you use just plain lamp cord, energy flows between wires. It is strictly not between wires since electric fields bends, but also outside of the cable in-between planes like picture below shows:

https://www.google.com/url?sa=i&url=http%3A%2F%2Fwww.vias.org%2Falbert_ecomm%2Faec06_transmissio...

"Way too much info"
Guilty as charged  :)

So, you guys are saying the energy is the signal? What is it that travels down the near lightspeed? Current? the EM wave? Surely not the Poynting vectors, yes? Something must be traveling down the inside of the conductor, otherwise the type of metal, gauge and purity of the conductor wouldn’t matter, yes?

Electric current in the cable is a flow of electric charge. Exactly the same amount of electric charge that leaves the source comes back to it. Energy is delivered from source to load by electromagnetic field in between wires. It is called Poynting field and direction of this electromagnetic wave can be determined by Poynting vector. Presence of the load creates voltage drop - an electric field between wires. Current in the wire creates circular magnetic field around it. These electric and magnetic fields are perpendicular. If you imagine them as X-Y axis then Poynting vector will be perpendicular to them as "Z" axis. This vector points always in the same direction, (from source to load) even with ac current, since both electric and magnetic fields change direction at the same time. In the coax cable, that was mentioned, whole energy (electromagnetic field) flows inside thru dielectric between wire and the shield.

This was one of the few times that when I read it, it made perfect sense, and then it just evaporated into the ether. I swear I almost visualized it. Thanks for that fleeting moment of clarity.

All the best,
Nonoise

Kijanki is the best. No nonsense....just the facts. 👍. Quick and concise. 

But in fact it doesn’t answer the question posed by the OP. Otherwise it’s fine. He might as well say the sky is blue. 

The E and M fields that are the Poynting vectors are just that - fields. Electric field and magnetic field. Not to be confused with electromagnetic waves. Fields are stationary. EM Waves travel at near lightspeed in a medium. So, if I’m not mistaken and I don’t think I am, that means the EM wave travels INSIDE the conductor. The E and M fields lie outside the conductor. They are stationary all along the length of the cable or wire. That explains why the type of metal, the purity of the metal and the physical non-symmetries of the metal influence the sound.

Electric charge moves together with electromagnetic wave at fraction of the speed of light in vacuum, dependent on dielectric (60-70%).
What moves slowly in the wire is electron (drift velocity) - practically standing still at the audio frequencies.  Electron doesn't have to be a carrier of electric charge - in water it is the ion.  Electric and magnetic fields are constantly changing with alternating current, but energy is delivered on the outside of the wires from source to load (for AC and DC).  The unit of Poynting Vector is "watts per square meter".  Picture with battery and resistor illustrates this: 

https://en.wikipedia.org/wiki/Poynting_vector

I would like to add, that it is as far as I can understand it and, of course, I can be wrong  (I was wrong once in 1964)  :) 

What you just wrote might be true. But even if it is true it doesn’t answer the Original question posed in the OP.  We all know what the Poynting vectors are, since 1884. We also know the sky is blue. You might as well write out Maxwell’s equations and declare victory. 🤗

OK, let’s take a simple example of a fuse in an AC circuit. Describe in as much detail as you can what is traveling through the fuse wire and what is traveling outside the wire.

An audio signal is a representation of sound using electrical voltage in analog and binary in digital. That's  the first part. 
https://en.m.wikipedia.org/wiki/Audio_signal

The medium it travels in geoffkait explained above.

, if I’m not mistaken and I don’t think I am, that means the EM wave travels INSIDE the conductor. The E and M fields lie outside the conductor. They are stationary all along the length of the cable or wire. That explains why the type of metal, the purity of the metal and the physical non-symmetries of the metal influence the sound.

The most valuable thing you can do is take a couple of courses in electronics at your local community college. This will lead you to physics etc. It will also help you understand those little bands of color on resistors, how capacitors work (build one?) and what transistors do. A basic understanding will help in many ways. Some colleges even offer classes in sound reinforcement and audio production that will help you understand microphone types, sound processing, recording etc etc.

I would like to add, that it is as far as I can understand it and, of course, I can be wrong (I was wrong once in 1964) :)

If it were you behind these hairdos, I don't know if I can ever forgive you:
https://www.theatlantic.com/photo/2014/05/1964-the-world-50-years-ago/100743/

All the best,
Nonoise

An audio signal is purely a varying electrical voltage & current, just that .  Nothing more.
You can always get into the atomic & particle physics aspects of what makes up electricity itself but nobody really knows :-)  And it does not really matter anyway.

Is that the reason, say, a Teflon dielectric, insulation, will cause ICs to sound better than cheap PVC insulation?

Capacitance between plates is proportional to overlapping area and relative permittivity while inversely proportional to distance.  Relative permittivity of the material (also called Dielectric Constant) is a measure how fast given material can be polarized by electric field in comparison to vacuum.  Permittivity is inversely proportional to speed of electromagnetic wave in material, squared.  Speed of electromagnetic wave thru material depends on how fast material absorbs and releases energy (dielectric absorption).  Because Teflon has low Dielectric Absorption electromagnetic wave travels faster thru it, than for instance thru PVC.  As a result of it capacitance between Teflon wires is smaller than between identical PVC wires.

Of course being straight proportional or inversely proportional is a
simple equation for plates, but much more complicated for the wires but proportionality (dependency) is still the same.

It is possible to lower Dielectric Constant of any material by foaming it or oversizing it around the wire as hollow tubes (air has lower dielectric constant than Teflon).  My ICs have hollow oversized tubes made of foam Teflon resulting in 6.1pF/ft  while typical wires have about 25pF/ft.

An audio signal is purely a varying electrical voltage & current, just that . Nothing more.

Let me start simplifying it:

INDIAN SEE EAGLE OVER RABBIT  (instead of Ohm Law I=E/R)  ;)

Then there is that pesky Square wave...

IF you want to blow a gasket or three, you can do FFT ( I use studio 6 toolbox ) and watch the waveform go by....
Combining three or four sine waves gets messy in a hurry, real music isn’t sine waves.. or simple harmonics- as the late great Roger Modjeski was fond of saying “ what is the 5th harmonic of Beethoven 9th “

for grins, I will put up a screen shot ( Audiogon is so freaking dark ages... ) in my Poverty Bay system pages.. It will be of Steely Dan - The Royal Scam

oh, I am all for childlike wonder but not the ego....

Jim,
Electric current is a flow of electric charge. Electric current produces magnetic field around the wire. Any change in amount or direction of electric charge produces a change in direction and amount of magnetic flux around the wire. Change in the amount of electric charge that flows in the wire, as well as amount of magnetic flux that follows, both change at the fraction of the light speed.
Presence of the load creates electric field between wires. Both electric and magnetic fields are necessary to transfer the energy from source to load. Both fields together create energy field (Poynting vector) toward load (that absorbs it), that follows changes at the same speed.

In case of the current thru the fuse, that was mentioned, energy field will be traveling thru all the space between fuse and the return wire. The further they are the larger this filed will be. It is wise to keep them close to reduce it.

As for the purity of the metal - the obvious thing is resistance of the wire, that causes power loss, less obvious is inductance of straight wire, affecting wire impedance, especially at higher frequencies (inductance is smaller for thicker wires). Second aspect of purity is that impurities in the wire reside between crystals of metal. Typical impurity of the copper is copper oxide (that is a semiconductor). What is audible, and what isn’t I don’t know. Often it is a placebo effect but I don’t mind. If placebo effect works it is worth the money :)

As for silver wire sounding different than copper - I have no idea. The obvious difference is lower resistivity of silver, but it is a very small difference. Silver, according to many, produces brighter sound. Maker of my cables, Acoustic Zen, adds few percent of copper into silver. To me it is all on the verge of black magic.

We've got to get a decent audio system up to the ISS to test that vaccuum thing....

"Hi, Elon?  We've got this concept that you can dance to...."

Crewed Dragon leaves shortly...;)

Elon is not answering the phone, it looks like when one of his sick Tesla employees cough the pointing vector of the virus changes....

jea48

djones51


The medium it travels in geoffkait explained above.

, if I’m not mistaken and I don’t think I am, that means the EM wave travels INSIDE the conductor. The E and M fields lie outside the conductor. They are stationary all along the length of the cable or wire. That explains why the type of metal, the purity of the metal and the physical non-symmetries of the metal influence the sound.

@ djones51

If true, kijanki, almarg, herman, Ralph Morrison, and countless other professionals are wrong.

>>>>>I can live with that. Even almarg agrees the signal is an electromagnetic wave that travels at near lightspeed. The E and M fields are not waves. They’re fields. Besides, it’s customary for professionals to not always agree. 

jea48
@geoffkait

Part of the OP’s question:

and what exactly is the medium it travels through in a cable??

The signal energy travels in the space between the wires. Not in the wires.
More precisely through the dielectric insulation covering the wires.

>>>>>The signal energy is not the signal. That’s why the conductor’s physical properties affect the sound. The energy is the E and M fields. The signal is the electromagnetic wave. I thought we already settled that.

jea48
@geoffkait

Now you are changing the subject.

Subject:

Simple question, or is it...

What exactly is an audio signal made of, and what exactly is the medium it travels through in a cable??

Next you will be changing the subject to fuse directionality.

>>>>>I didn’t change the subject. The simple case of a fuse is a good opportunity or someone to explain the electric signal and how it’s affected by the wire’s physical properties. You can not divorce the cable from the conductor. The fuse is representative of other wires in the audio system. If you feel more comfortable you can use power cord instead of fuse. Pick anything you want. You be the decider. Why dismiss directionality so harshly? Does it make you nervous? All wires are directional. Agree/disagree?

You now understand it?

It was only a matter of time before somebody name-dropped “Maxwell’s equations” to support his argument. Just as predicted yesterday. Beautiful! It was bound to happen sooner or later. Don’t you see 👀 the wave is not the energy? Hel-loo! That’s why it matters what the conductor is made of, no? If the signal was outside it who would care what the conductor is made of? Why aren’t you still scratching your head? 🤔 The Characteristics of the signal determine the characteristics of the energy, no?  The E and M fields don’t just pop up by themselves.

tomic601, yeah, I've read that C19 has been going thru Chchchchchanges.....

Oh, well....like I pointed out to our aging dogchild this morning, this 'existence' stuff is a mixed bag....as she grumbled and grunted thru her 'wake up' routine. *G*

The problem with discerning electron flow thru a medium seems to follow the same issues with quantum states.  But it does keep folks buying wire....;)

jea48

jea48
@geoffkait

Thanks to kijanki’s explanation we know how the dielectric can have an affect on the signal.

>>>>>I’m fairly certain everybody already knew that. But thanks just the same. Besides, it’s actually a little bit irrelevant, don’t you think? That’s one of those “the sky is blue“ type comments. So, going back to the fuse example, come up with any idea? It’s even got a dielectric! 🤗 

I've been doing a lot of reading mainly here the link jea48 gave.

 http://amasci.com/elect/poynt/poynt.html
 
The great thing about this link is there are a whole lot of other articles besides the one on Poynting vectors. 
Two things are at play the charge flow in the wires which is very slow and forms a circuit. Measured in amperes which is "one Coulomb of charge flowing per second". So far so good.

Also there is Energy flow which flows between and around the wires measured in watts, a quantity of electrical energy flow per second. Energy is measured in Joules so 1 joule a second is 1 watt.

 What is electrical energy, it's made of electric fields and magnetic fields, Electromagnetism. These two things flow in a circuit at the same time. Charge flow in the wires very slow in a continuous circuit and energy flow outside the wires from the source to the load. 

We're left with one thing What are Joules?  Joules of Electric energy are made from Electromagnetism they are flying around between the source and load and are the same stuff as radio waves but in this case they ATTACH  themselves to the wire and FLOW along the columns of movable electrons in the wire, the charge flows in the wire slow, the energy flows outside the wire at almost the speed of light and the Joules flow in the electron columns carried with the energy. 

OK, you convinced me. Waving the White Flag here, guys! 🏳 Going back to metal clothes hangers ASAP.

Why wave the white flag, you're right the Joules which are in the electromagnetic wave are in the wire. The wire carries the signal, the signal isn't the energy flow. At least that's the take I'm getting from all those links jea48 posted. Well other papers from the link.