Please don't roll your eyes, or banish me from the forum for asking this question but what is it that makes the drivers move air? There is a motor and magnets that move the diaphragm in and out. There is a fairly simple wire that travels from the amplifier to the driver. I understand the volume control limits the number of electrons that can flow to the driver from the amp via that simple wire. But how does the speaker know whether it is a high or low tone that is to be produced? It's been many years since my college physics classes, and honestly I did much better in classical mechanics than I did with nuclear/electricity back then.
I think this is a pretty fundamental question that is fairly easily answered by most of the people here on the forum. Can someone explain it to me simply? Thanks and I hope you have not lost all respect for me by asking this. Also, I wasn't sure the best place to post this question, so admins feel free to move it.
I think this is a pretty fundamental question that is fairly easily answered by most of the people here on the forum. Can someone explain it to me simply? Thanks and I hope you have not lost all respect for me by asking this. Also, I wasn't sure the best place to post this question, so admins feel free to move it.
It's an analog system, and so the current in the wire from the amplifier changes in amount (number of electrons per second) and direction, in relation to the loudness (magnitude) and pitch (frequency) of the sound. Then the speaker cone moves in relation to these aspects of the current going through the voice coil, and then the air moves in relation to the speaker movement. The hallmark of a low distortion (linear) system is that the output frequency is the same as the input frequency.
How loudspeakers work - Explain that Stuff
How loudspeakers work - Explain that Stuff
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The speaker cone vibrates in a complex pattern that represents an amalgam of all the different frequencies present in the music signal.
The magic occurs in the human ear/brain which unravels the ensuing complex pattern of vibration in the air and interprets it as music!
A knowledge of Fourier Analysis may aid your understanding:
Fourier analysis in Music - Rhea
The magic occurs in the human ear/brain which unravels the ensuing complex pattern of vibration in the air and interprets it as music!
A knowledge of Fourier Analysis may aid your understanding:
Fourier analysis in Music - Rhea
Bob, once you’ve invested, digested and excreted the redundant fibre of all that will be suggested herein, I’d also recommend The Soul of Sound. Start with the Soul of Sound The Soul of Sound
Short and simple: Look at an oscilloscope plugin when listening to music from a computer.
The speaker membrane attempts to move back and forth much the same as the oscilloscopes squiggly dancing lines go up and down.
Because the voltage goes through a coil creating a magnetic field and it causes the cone to move because the magnet of the driver is a fixed reference.
The speaker membrane attempts to move back and forth much the same as the oscilloscopes squiggly dancing lines go up and down.
Because the voltage goes through a coil creating a magnetic field and it causes the cone to move because the magnet of the driver is a fixed reference.
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This is the basic chain for the simplest sound or Music RE-producer, emphasis on *re* , meaning we want the original sound back.
Louder, somewhere else, or both.
1) a musical instrument, a person singing, hands clapping, a thunder in the sky, lots of things produce Sound.
What is sound?
A variation in air pressure.
How is it produced?
Sound sources as mentioned above produce such variation.
There are different mechanisms but one of them which is quite intuitive to grasp is that some kind of membrane or moving surface in contact with air vibrates and transmits such vibration to air.
Examples: a guitar/violin/cello/drum_skin/bell/gong vibrates and transmits such vibration to air.
There are other mechanisms, for example air in a flute or organ pipe vibrates itself and since it´s not in vacuum transmits such vibration to surrounding air.
Why does it matter to us?
2) such vibration / acoustic wave / variation in pressure travels through air, reaches our eardrums, a sensitive membrane, which detects it and sends it to our brain, so we can hear.
So far no Electronics, no Speakers, no wire, no Electrons, just pure , direct, Acoustical sound.
Do we agree so far?
If not, reread it again until it clicks, because sound "capturing" and reproduction achieves the same (or tries to) , just using some technology.
Ok, now let´s introduce some devices in the (alternative) path.
3) we use a Microphone to "capture" sound.
Nothing more complicated than a light thin membrane which vibrates when reached by a soundwave (air pressure variation).
Emphasis on light thin , and equivalent to our eardrums.
Instead of nerves, it has a coil of wire submerged in a magnetic field; when coil moves pushed by the membrane, it generates a signal voltage which, hopefully, is a perfect copy of the soundwave reaching it.
But ... but ... you said "perfect copy" ... we were talking an acoustic wave ... now an electrical one? WTF?
Well, in Physics we have very clever elements called transducers, which transduce/convert" one kind of phenomenon into another.
In this case, a sound pressure variation into an electrical voltage variation.
Ok, what do we do now?
4) we send that tiny voltage variation to an amplifier .
basically an element, we often call it a "black box" meaning we don´t really care what´s inside, mainly because there´s many ways to do it, in principle including tubes, transistors of different kinds or combinations of them; the main point being that at its output we get more voltage than we put in.
Again, hopefully a perfect copy, just way stronger.
And in power amplifiers, more voltage and more current, which combined mean more power ... lots more.
Again, hopefully a perfect copy, just way stronger.
Don´t lose track of the fact that from the beginning, we are working with a copy of the original sound, just we are now in the Electronic realm.
And why Electronics, out of the immense field of Physics?
Because we learnt to easily amplify electrical waves, immensely, almost without limit, what we can not do (so far) in other Physical realms.
5) so now we have a hugely larger voltage and current electrical signal, which is a perfect copy of the original sound.
Problem is, we don´t directly hear electrical waves, but Acoustical ones.
No problem, we again use the wonderful Human invention, the transducer, but now connected backwards: that voltage+current=Power wave drives a coil inserted in a magnetic field, which is nothing more than an electric motor .
We can not (or hardly) hear the voice coil itself but if we glue it to a membrane, it will be able to move air, big time.
So if we did our homework properly, we have the same original soundwave, but hugely louder ... or real far away ... or both.
So now we can:
* perfectly hear a singer even if audience is 40000 people ... or more.
* talk, in a normal voice, with somebody in China
* a deaf guy can now hear again
That´s the basic mechanism, we can also (using other clever devices) make sound "travel in time" by recording it and playing it back later ; make it travel through space, including vacuum, by using radio waves; mix people which did not sing or perform together into a single recording, heavily modify original sound into anything we like, and thousands of other wonders, but the basic mechanism is what I described above.
Louder, somewhere else, or both.
1) a musical instrument, a person singing, hands clapping, a thunder in the sky, lots of things produce Sound.
What is sound?
A variation in air pressure.
How is it produced?
Sound sources as mentioned above produce such variation.
There are different mechanisms but one of them which is quite intuitive to grasp is that some kind of membrane or moving surface in contact with air vibrates and transmits such vibration to air.
Examples: a guitar/violin/cello/drum_skin/bell/gong vibrates and transmits such vibration to air.
There are other mechanisms, for example air in a flute or organ pipe vibrates itself and since it´s not in vacuum transmits such vibration to surrounding air.
Why does it matter to us?
2) such vibration / acoustic wave / variation in pressure travels through air, reaches our eardrums, a sensitive membrane, which detects it and sends it to our brain, so we can hear.
So far no Electronics, no Speakers, no wire, no Electrons, just pure , direct, Acoustical sound.
Do we agree so far?
If not, reread it again until it clicks, because sound "capturing" and reproduction achieves the same (or tries to) , just using some technology.
Ok, now let´s introduce some devices in the (alternative) path.
3) we use a Microphone to "capture" sound.
Nothing more complicated than a light thin membrane which vibrates when reached by a soundwave (air pressure variation).
Emphasis on light thin , and equivalent to our eardrums.
Instead of nerves, it has a coil of wire submerged in a magnetic field; when coil moves pushed by the membrane, it generates a signal voltage which, hopefully, is a perfect copy of the soundwave reaching it.
But ... but ... you said "perfect copy" ... we were talking an acoustic wave ... now an electrical one? WTF?
Well, in Physics we have very clever elements called transducers, which transduce/convert" one kind of phenomenon into another.
In this case, a sound pressure variation into an electrical voltage variation.
Ok, what do we do now?
4) we send that tiny voltage variation to an amplifier .
basically an element, we often call it a "black box" meaning we don´t really care what´s inside, mainly because there´s many ways to do it, in principle including tubes, transistors of different kinds or combinations of them; the main point being that at its output we get more voltage than we put in.
Again, hopefully a perfect copy, just way stronger.
And in power amplifiers, more voltage and more current, which combined mean more power ... lots more.
Again, hopefully a perfect copy, just way stronger.
Don´t lose track of the fact that from the beginning, we are working with a copy of the original sound, just we are now in the Electronic realm.
And why Electronics, out of the immense field of Physics?
Because we learnt to easily amplify electrical waves, immensely, almost without limit, what we can not do (so far) in other Physical realms.
5) so now we have a hugely larger voltage and current electrical signal, which is a perfect copy of the original sound.
Problem is, we don´t directly hear electrical waves, but Acoustical ones.
No problem, we again use the wonderful Human invention, the transducer, but now connected backwards: that voltage+current=Power wave drives a coil inserted in a magnetic field, which is nothing more than an electric motor .
We can not (or hardly) hear the voice coil itself but if we glue it to a membrane, it will be able to move air, big time.
So if we did our homework properly, we have the same original soundwave, but hugely louder ... or real far away ... or both.
So now we can:
* perfectly hear a singer even if audience is 40000 people ... or more.
* talk, in a normal voice, with somebody in China
* a deaf guy can now hear again
That´s the basic mechanism, we can also (using other clever devices) make sound "travel in time" by recording it and playing it back later ; make it travel through space, including vacuum, by using radio waves; mix people which did not sing or perform together into a single recording, heavily modify original sound into anything we like, and thousands of other wonders, but the basic mechanism is what I described above.
For this question you could have consulted a children's science book and a book of Physics intended for adolescents. In the case of consulting a book of Physics, read about longitudinal waves. Sound waves in air belong to this category.
If you think about sentient beings like human beings, they only have two ear drums. The ear drums vibrate in accordance to the incoming sound waves, and the displacement of the diaphram from its rest position, depends on the instantaneous pressure applied to it. This instantaneous pressure is the result of vibrating air molecules which constitute a sound wave.
A speaker diaphram can be seen as the reverse of an ear drum. Instead of vibrating in synchrony with an incoming sound wave, it vibrates in synchrony with an electronic current pushing and pulling the air in contact with it. This pushing and pulling of air molecules generates a sound wave just like the diaphram of a voice box.
If you think about sentient beings like human beings, they only have two ear drums. The ear drums vibrate in accordance to the incoming sound waves, and the displacement of the diaphram from its rest position, depends on the instantaneous pressure applied to it. This instantaneous pressure is the result of vibrating air molecules which constitute a sound wave.
A speaker diaphram can be seen as the reverse of an ear drum. Instead of vibrating in synchrony with an incoming sound wave, it vibrates in synchrony with an electronic current pushing and pulling the air in contact with it. This pushing and pulling of air molecules generates a sound wave just like the diaphram of a voice box.
Bob, thanks to the interweb, there’s likely close to a googol of accessible attempts to explain the origin and history of “loudspeakers”, this is as probably as good a departure point for what can become an Alice in Wonderland journey down the rabbit hole. I’d pack a picnic lunch if I were you.History and Types of Speakers
And Wikipedia is another source of confusion Loudspeaker - Wikipedia
In the 140+ years since Johann Reis, there have been many approaches taken to precisely control the movement of air required to replicate / amplify natural sounds, but by far the bulk of what we think of as modern speakers probably follow the Rice-Kellog / electro-dynamic model.
And Wikipedia is another source of confusion Loudspeaker - Wikipedia
In the 140+ years since Johann Reis, there have been many approaches taken to precisely control the movement of air required to replicate / amplify natural sounds, but by far the bulk of what we think of as modern speakers probably follow the Rice-Kellog / electro-dynamic model.
Start by thinking of a simple electrical signal flowing through a speaker wire, a sine wave. Wave 1 in this image (copied from a brief search). If you add in a second sine wave at a different frequency, the result isn’t two separate waves traveling along together. Instead, the two are superposed into a single, more complex waveform.
When this single electrical signal is sent to the speaker, the speaker cone simply does its best to follow this electrical waveform. It’s not being asked to produce a low tone and a high tone, but a single superposition of low and high tones.
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Thanks everyone for your replies so far. Rayma may have come closest to the type of answer I was looking for. JmFahey went above and beyond in describing the entire system, and TSmith gives me some good insight. I was really asking what is moving thru the wire and how it is moving as it enters the speaker terminals. It seems like I need to go back to my physics and renew my knowledge of electricity. Which, as I mentioned, wasn't my strong suit in college.
I can understand the electro-dynamic speaker, but those early horns must be powered by some kind of witchcraft.
First of all, electrons are like the links in a bicycle chain. You have to have a return path because aside from "static electricity", for every electron traveling in one direction, another has to return.
Next, the motor pushes and pulls the speaker cone as the electricity travels forward and backward. If the electricity reverses very fast then so does the speaker cone, ie for a high pitch tone. For a low pitch tone, the electricity reverses back and forth relatively slowly.
A microphone creates an fluctuating electrical voltage that represents the movement of the microphone diaphragm and a speaker just reverses the process.
Next, the motor pushes and pulls the speaker cone as the electricity travels forward and backward. If the electricity reverses very fast then so does the speaker cone, ie for a high pitch tone. For a low pitch tone, the electricity reverses back and forth relatively slowly.
A microphone creates an fluctuating electrical voltage that represents the movement of the microphone diaphragm and a speaker just reverses the process.
Mathematics states that a complex waveform can be expressed as a series of sine waves with a range of frequencies. For perfect waves, like a square wave or a triangular wave, the series is infinite. Audio signals cannot have an infinite number of harmonics. The range is limited by hearing perception. A non repetitive pulse can also be expressed as a sum of sines with a range of frequencies.
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