"To make any speaker diaphragm move in and out two wires are necessary. That’s why audio circuits are all AC. One wire makes the diaphragm move OUT, the other makes it move IN."
That's so bad, it isn't even wrong....
Jan
That's so bad, it isn't even wrong....
Jan
I almost forgot to mention, when the signal is going away from the speaker on either wire (which it will be 50% of the time) it has no affect on the sound. The signal only has an affect on the sound when it’s going toward 🔜 the speaker.
Consider this. Concentrate on understanding Ohms Law. You will be miles ahead when done.
https://www.amazon.com/Grobs-Basic-Electronics-Fundamentals-Simulations/dp/0073250368
https://www.amazon.com/Grobs-Basic-Electronics-Fundamentals-Simulations/dp/0073250368
And strangely enough, actual electrons travel at less than walking speed. You could race ahead of them up and down a speaker wire. We're all mostly wrong in the way we think about electricity, but we have no choice, because the modern conception is too impossible to believe. But what we do have is a flawed but completely workable model of voltages and currents, and muddle through despite. The Great Juju notices not the models of fallible humanity, but motors work anyway.
All good fortune,
Chris
All good fortune,
Chris
Electrons only move about a millionth of an inch at one time in an audio circuit. And since it’s an AC circuit their net distance traveled is zero. Does that surprise you?
Well yes because distance is usually not directional and sums positive. Net displacement is zero, but electrons move at high speed due to thermal energy and diffuse rapidly (they are responsible for most of the heat conduction in metals for instance). The average drift velocity of the electrons in a wire is what carries the current, and this indeed is very small, usually measured in mm/s.
Each cubic mm of copper has about a dozen coulombs of charge in its free electrons, so 1mm/s drift in a wire of area 1mm^2 is about 12amps, but each electron is all over the shop at about 1000 km/s due to thermal energy but they all average out to a miniscule noise current that can be happily ignored.
But it’s the drift velocity that matters, because those drifting electrons - the free electrons - carry the charges. You can ignore the thermal energy motion. Current is simply the sum of all the moving charges (free electrons). Current, by the way, is a scalar quantity and has no direction. The e and b fields are orthogonal to each other and to the direction of free electron motion.
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The Great Juju is tolerant of our efforts to understand the Mysteries, but has her limits.
Caution, and respect the Mysteries, 'Nuf said,
Chris
Caution, and respect the Mysteries, 'Nuf said,
Chris
Current is definitely signed, defined as the rate of flow of charge through a given surface with a reference direction, and its sign denotes the direction of flow relative to the reference. Current elements are vectors, current density is a vector field - current is often associated informally with a direction as if it was a vector.
Really insightful! I’ve just started reading books of Ralph Morrison, it’s full of interesting tidbits like this.
Speaker signals?
Usually, the red and black from the amp are signal and ground respectively. The red swings AC from positive to negative in line with the signal waveform, while the black is held at ground at the amp (with the two channels often common grounded). It's all driven from the red, and no signal is pushed or pulled on the black.
In a bridged amp (or other push-pull arrangements), the two speaker connections carry opposite phase signals, with neither being tied to ground. (And as an aside, that's why if you want to try bridging two amps, you need to be sure they're not internally bridged to start with.)
Usually, the red and black from the amp are signal and ground respectively. The red swings AC from positive to negative in line with the signal waveform, while the black is held at ground at the amp (with the two channels often common grounded). It's all driven from the red, and no signal is pushed or pulled on the black.
In a bridged amp (or other push-pull arrangements), the two speaker connections carry opposite phase signals, with neither being tied to ground. (And as an aside, that's why if you want to try bridging two amps, you need to be sure they're not internally bridged to start with.)
It’s not exactly true, there is a small E field inside the conductor (see attached)
Electromagnetic theory is really hard and a really different way of thinking about electronics. We lump everything into elements: R, C, L. This allows us to actually have a handle on what is going on.
I don’t why you are pretending it’s all obvious, and getting stuff wrong, it’s really hard. Why not read a book and get things right and then come and teach us. I mean that genuinely - you seem to know a lot already but have a bit of a bad attitude.
Interestingly, if the two posts are the same color, there is no way to know which is connected to gnd in the amp, unless you cheat and measure each post to the amp chassis.
Jan
Uh, the signal travels in both wires that are attached to the speaker. So you couid say each wire Carrie’s 1/2 the complete audio signal. Does that surprise you? 😲
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