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In Reply to: RE: "How electricity flows in an AC circuit" posted by Ugly on August 12, 2022 at 18:42:39
The energy flux density, I.e., the Poynting vector, is the cross product of the E and B fields that alternate with each other along the axis of the conductor. The E and B fields are orthogonal to the axis of the conductor and to each other. That's why it is said the "signal energy" lies outside the conductor. But it's also true that the E and B fields are produced by the motion of the free electrons. Which came first, the chicken or the egg?Recall there are two conductors in audio, + and - you can call them, each one Carrie's half the audio waveform, you could say. It's the alternating motion of free electrons that create sound in your room. Hel-loo! Try to escape your reality tunnel.
Todays tip: audio cables are not waveguides nor do they act like waveguides.
Edits: 08/13/22 08/13/22 08/13/22 08/13/22Follow Ups:
Do you even slightly recall your original premise for this thread? Here is a reminder..."Here is how an AC signal travels in a coax cable."
Your attempts to divert the conversation to a talk about free charges was originally very very cute and all but as soon as we all realized it is a logical fallacy to change the subject and expect that to have some meaningful relevance I figured/hoped we'd all get bored with that and move back into discussing the originally promised subect.
"Todays tip: audio cables are not waveguides nor do they act like waveguides"
So now we are constrained to only be talking about audio frequencies are we? How convenient. Weird how you waited until now to mention it.
I know you may not be free like some of us but I will continue to refer to coax as waveguide just as the rest of the universe will, whether you are in agreement or not, since that is its typical usage.
Feel free to add DC to your coax, for all I care. Sounds like your local authorities are far more oppressive, however. You may want to watch it.
"But it's also true that the E and B fields are produced by the motion of the free electrons."
Correction: a charge has an associated E field regardless of whether it has achieved net motion due to an external field or not.
Correction 2: A charge trapped in an e field, which has been forced to travel in the path of a waveguide, at a resultant drift velocity, is not free.
Who cares about E or B field of free echarges? You?
Nothing of use occurs until until external fields are applied.
Is there some poynt you are trying to make?
Edits: 08/13/22 08/13/22 08/13/22 08/13/22 08/13/22 08/13/22
It appears you fell into my trap, I wanted to talk about audio cables all along. If you feel more comfortable talking about transmission lines and waveguides my suggestion is start your own thread. It appears you're not familiar with the Poynting vector as your so called corrections make no sense. Maybe you should research this whole subject, Google is your friend.Did you miss the subject line for this discussion, How electricity flows in an AC circuit?
What am I looking for? I'm looking for an answer to my oft repeated question, what is the audio signal in audio cables? In order to make design decisions on cables it would be helpful, important, to know what the "audio signal" is so that distortion and noise can be minimized.
Edits: 08/13/22 08/13/22 08/13/22
"so that distortion and noise can be minimized."
But you closed the conversation off to considering anything but coax. Why ignore an entire audio industries wealth of knowledge by immediately making off limits the industry standard circuit topologies designed to accomplish those exact goals?
You misunderstand. I only used the *quote* in my OP to raise the general subject of cables. More specifically audio cables. Obviously, I don't wish to limit the discussion to coax. Coax happens to be the cable used on the Wiki page for illustrating Poynting vector. It's just a jumping off Poynt. I'm primarily interested in audio cables, not "industry standard circuit topologies" What is the "signal" in audio cables? And how do internal and external forces affect the "audio signal?" How does the signal get distorted? If someone believes all cables sound about the same that's OK too.
Edits: 08/17/22 08/17/22 08/17/22 08/17/22 08/17/22
Seems like going out of the way to ignore industry topology trends, especially when wondering about best usage of something regularly used by the industry such as cables, you risk not seeing some important data points that could be valuable. For example, choosing a truly well balanced circuit and fully bipolar differential signals allows a certain level of noise and distortion rejection/cancelling completely unavailable to a system utilizing pure single ended/coax signals and hardware. You can still throw a picture of some twisted pairs in the fridge, you know.
Edits: 08/22/22
The trouble is that "industry standards" or "industry data points" - whatever that means - has little relevance to the discussion at hand. What industry are you referring to? The audio industry - specially the high end audio industry - has very few standards or requirements or regulations. There are no standards for polarity, wire directionality, fuses, power cords or cables. [NOTE: I'm not referring to function here, I'm referring to SOUND QUALITY.] Obviously a fuse must function to protect the electronics, for example. The debate is still on going regarding balanced vs unbalanced cables anyway. Ditto for shielded vs unshielded, or copper vs silver conductors. I'm not referring to theoretical functionality, I'm referring to SOUND QUALITY.There are no standards for sound quality, not the ones I'm talking about. Sure there are specifications, but that's not the same thing as sound quality as we know. The same cables or electronics or CD can sound radically different in different systems and different rooms.
The question remains: What is the "audio signal" in cables? If we knew what exactly were dealing with, what is being affected by internal and external factors, like RFI and vibration, we could build better fuses and cables. And even better amplifiers. I'm not referring to theoretical physics or electronics, or even functionality, I'm referring to SOUND QUALITY.
1. Audio waveform
2. Current
3. Electrons
4. Voltage
5.:Poynting vector
6. Magnetic field
7. Electric field
8. Electromagnetic wave
Edits: 08/23/22 08/23/22 08/23/22 08/23/22 08/23/22 08/23/22
Just couldn't figure out what industry I was referring to, eh? mmmhmmm fun game.
Who said anything about "sound quality", however it is you would have percieved such a thing? For all I know you are one of those people who likes more noise and distortion than the program material contains.
Earlier you said you wanted to find a way to achieve lower noise and distortion so I recomended balanced/differential..... Which *you* may still be debating the merits of....don't know, but others have quantified these things long ago. No doubt you will rationalize rejecting all existing empirical evidence with a goofy smile and a hand wave and that is AOK by me.
I just brought up sound quality. Does that surprise you? Why else would I be interested in the "audio signal" in cables and how to improve it? Why else would I say, once you can identify the "audio signal" in cables then you can go about trying to decrease the noise and distortion? I like your goofball comments, though. We're about through here, aren't we?
Edits: 08/24/22
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