These are words to explain the actions. Piston is something that goes to-and-fro. Frequency is something which explains speed it bends one way and then bends the other way. Well, the word wavefront is coined word, a wave doesn't really have a front, when a wave hits some object, it is at some level of the wave. It might be even at zero, but the next wave hits the same object (the ear tract and through it), some point of the wave above or below zero, so we hear different sounds. Bit off topic.
The manufacturers don't talk much or at all about the vibrations happening on the cone surface, which are larger at the bottom, smaller at the top. Anyway, while the current is going through the coil, it gives sound, even without any surface attached to it, for it vibrates, and in every plane. In a audio driver, its side movements are somewhat restricted at the top with suspension and the cone's bottom, but they happen. Some hear a coil "whine" sometimes. Every surface around the coil vibrates in audio driver, even the basket. And, give sound.
OK, the question still is how the cone "radiates" the sound waves. Does it move like a solid piston, as a solid, or as a thin angled surface, which can also bend, or vibrate on its own plane(s)?
The cone is only finitely stiff. If you look at a cross-section of the cone under motion, it will be moving front-and-back with some simple Hooke-like bending from coil former joint to surround joint.
Some scientific papers found in the net. One from University of Southampton, UK and the other from University of Technology, Dresden, Germany.
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Guys, chdsl is trolling you.
This fake thread will last only as you want to sink valuable time into it.
The "seemingly" innocent "noob who has NO clue" questions in posts 1 and 4 quickly turns into derising fellow user tmuikku in posts 6 and 8 and 13, where it gets frankly insulting.
Post 24 linking to papers on advanced Acoustics is absolutely inconsistent with the "innocent noob" image shown at thread beginning.
DON´T FEED THE TROLL
This fake thread will last only as you want to sink valuable time into it.
The "seemingly" innocent "noob who has NO clue" questions in posts 1 and 4 quickly turns into derising fellow user tmuikku in posts 6 and 8 and 13, where it gets frankly insulting.
Post 24 linking to papers on advanced Acoustics is absolutely inconsistent with the "innocent noob" image shown at thread beginning.
DON´T FEED THE TROLL
I said something I found in the net. I am still looking at other papers, but most probably won't link them here. Maybe, I shouldn't have linked any articles/papers at all. Not everyone has Physics background/knowledge.
Anyway, I have been doing the following; pasting rings on the driver cone at different distances from the center (one at a time, few together etc), pasting a plastic ball at the center, pasting a paper cone, one larger than the dust cover, one smaller than dust cover resting on it, and some more. It is up to you to test/experiment, if you so desire. It is DIY, after all. Not only DIY enclosure, but DIY on the driver itself. Find out how you can hamper or add to the cone vibrations and the type of sound you'd hear. You try, you find out, there's no other way.
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If you have one of the old "Whole Earth Catalog"s, they have a speaker project where they glue wooden sticks onto the woofer cone radially to stiffen it. Back in 1968. I always wondered about that idea.
I once took a strobe light and observed the motion of a drum head when struck. You could clearly see different parts of the flat head moving in relative motions. Today with bright LED illumination setup as a strobe, I'd expect you could see relative motion on a conical surface at various frequencies. The so-called "breakup". Never liked that name...
So you could approach this from an empirical observation on a particular speaker. Maybe even glue wood sticks across a particularly offending section. Or maybe even get to see what the "enable" process actually does. Or maybe see nothing -
I once took a strobe light and observed the motion of a drum head when struck. You could clearly see different parts of the flat head moving in relative motions. Today with bright LED illumination setup as a strobe, I'd expect you could see relative motion on a conical surface at various frequencies. The so-called "breakup". Never liked that name...
So you could approach this from an empirical observation on a particular speaker. Maybe even glue wood sticks across a particularly offending section. Or maybe even get to see what the "enable" process actually does. Or maybe see nothing -
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Dual cone angle, grooves in the middle (pseudo surround ?), varying cone thickness, at the top much thicker...separate parts of the cone radially vibrates differently creating different sound waves, even the dome in the middle (dust cap). One example below. Few more are out there...
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Watch an easy to buy full range speaker making music. How the cone distorts on its surface. How the shiny cone in the middle tweets, without moving.
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+1. Don't waste your time guys & girls. An 'innocent' question is asked by the OP in his first post, who a few posts later starts lecturing. The basic principles behind the operation of electrodynamic wideband drivers and their use of both piston (oscillatory) and resonant action are not a mystery, nor 'belief', just practical engineering, and anybody who wishes to learn can freely ask members who are familiar with the subject, of which there are a number here. Some of whom even design such drive units, or work with those who do.
Let's think this thru...first off we 'should' assume the structure of a cone is like any material, in that, it has a stretching value, a zone where it can be deformed & will return to its original 'length', past which will deform permanently.
So we are ramping up a force trying to move it, & assuming it has little mass, we easily move it on the voice-coil end...the structure deforms as a wave traversing the length until it reaches the surround. But what is happening when the applying force stops & reverses direction before the first application of force can move the entire length of the cone?
Let us not yet consider reflections of the wave when it reaches the end. Further, what speed is this applied force imparted into the cone, is it faster than the speed of sound as many materials do indeed traverse?
Can-o-worms here...
-------------------------------------------------------------------Rick.....
So we are ramping up a force trying to move it, & assuming it has little mass, we easily move it on the voice-coil end...the structure deforms as a wave traversing the length until it reaches the surround. But what is happening when the applying force stops & reverses direction before the first application of force can move the entire length of the cone?
Let us not yet consider reflections of the wave when it reaches the end. Further, what speed is this applied force imparted into the cone, is it faster than the speed of sound as many materials do indeed traverse?
Can-o-worms here...
-------------------------------------------------------------------Rick.....
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