Interesting idea;

[finkster]

well i counted eighty useless posts...including mine. Good thing Ed knows wtf hes talking about.

[skittlesRgood]

Out of audible range can still hurt. you cant here below 20 hz, but you can still feel it right.

competing with it is pointless,

If you did have a tone at that freq and it managed to get really loud it would hurt your ears more that lower notes that subs are intended to do, if anything could actually play that tone

But id say its kinda impossible.

21000hz is back at forth 21000 times per second, 20 mm each way, that many times a second would most likely destroy the driver.

also, If i did it right, if the cone is moving 40 mm 21000 times per second it would have to move 840 meters per second, and stop, then accelerate, then stop, then accelerate, again and again.

And 840 meters per second is already faster than the speed of sound

lol i tried to do the math too and i got 1909mph.

[Neo_frog]

Thank you Ed for making that post. I can't believe how fucked up this thread got and only three people made an attempt to help. The users on this site are seriously turning into shit holes.

[Neo_frog]

But to expand a little bit, theoretically, if you had a driver capable of the movement you suggested, most likely it would be uneventful. The supersonic motion would cause no significant impact to the integrity of the cone because there would be no build up of pressure. The driver for the most part would be stationary in it's environment (being the room), and the displacement of the cone, although faster than sound, would be constantly travelling away from it. If it were to create an excess build up with each linear motion, the frequency of the breaks would be the same as the signal and therefore would be "silent".

I guess you could relate the visual aspect to a propellor with 0 thrust spinning at 21000RPM. Nothing much happens but blurred circle.

[HHR Ed]

any vids of the bread van? that'd be awesome! and great explanation

I dont think there are any vids. That was before the days of youtube and build threads. But there are tons of articles.

It was Richard Clark's MTX bomb. the 60" woofer. and the creator of T3 Audio helped build it.

[HHR Ed]

Thread cleaned up.

Lets keep it clean boys.

[skittlesRgood]

But to expand a little bit, theoretically, if you had a driver capable of the movement you suggested, most likely it would be uneventful. The supersonic motion would cause no significant impact to the integrity of the cone because there would be no build up of pressure. The driver for the most part would be stationary in it's environment (being the room), and the displacement of the cone, although faster than sound, would be constantly travelling away from it. If it were to create an excess build up with each linear motion, the frequency of the breaks would be the same as the signal and therefore would be "silent".

I guess you could relate the visual aspect to a propellor with 0 thrust spinning at 21000RPM. Nothing much happens but blurred circle.

no no no lol. pressure has nothing to do with it. its physics. an object at rest wants to stay at rest. the coil would bast through the cone on the 1st movement because its not strong enough to handle the gforces created to move so fast. and the cone has to stop and restart its push. imagine if you went 1/2 a mile in 1 second then hit an immovable object and at the same time were thrown the opposite way at the same rate of speed. thats what the speaker would have to do.

but besides that, you think pressure cant be built up because its moving faster? the air still has to move out of the way of that cone and it will compress (pressurize) at the point of movement. the faster the object moves the more pressure is created. maybe your talking more about sustaining the movement and i have no idea what happens at this point. im talking about the very 1st push.

[Neo_frog]

no no no lol. pressure has nothing to do with it. its physics. an object at rest wants to stay at rest. the coil would bast through the cone on the 1st movement because its not strong enough to handle the gforces created to move so fast.

but besides that, you think pressure cant be built up because its moving faster? the air still has to move out of the way of that cone and it will compress (pressurize) at the point of movement. the faster the object moves the more pressure is created. maybe your talking more about sustaining the movement and i have no idea what happens at this point. im talking about the very 1st push.

At the very beginning of my post I mentioned a theoretical driver capable of withstanding the incredible forces. Newton's laws aside...

Pressure will build up, I never said it wouldn't. It will build up each time the cone moves back and forth, but due to the minimal travel, there will be no significant retention of compression to destroy it. That's why I made a point to mention the driver will be stationary, but the cone will be moving. Think about a plane travelling at the speed of sound.. In most cases, the plane would get destroyed from the incredible build up of sound waved travelling along side it. That's why they either travel under it, or faster.

[HHR Ed]

In a non-dispersive medium sound speed is independent of sound frequency, so the speeds of energy transport and sound propagation are the same. For audible sounds air is a non-dispersive medium. But air does contain a small amount of CO2 which is a dispersive medium, and it introduces dispersion to air at ultrasonic frequencies (> 28 kHz).[3]

In a dispersive medium sound speed is a function of sound frequency, through the dispersion relation. The spatial and temporal distribution of a propagating disturbance will continually change. Each frequency component propagates at its own phase velocity, while the energy of the disturbance propagates at the group velocity.

[Mr. Darkjustice]

In a non-dispersive medium sound speed is independent of sound frequency, so the speeds of energy transport and sound propagation are the same. For audible sounds air is a non-dispersive medium. But air does contain a small amount of CO2 which is a dispersive medium, and it introduces dispersion to air at ultrasonic frequencies (> 28 kHz).[3]

In a dispersive medium sound speed is a function of sound frequency, through the dispersion relation. The spatial and temporal distribution of a propagating disturbance will continually change. Each frequency component propagates at its own phase velocity, while the energy of the disturbance propagates at the group velocity.

somethin tells me my IQ isnt high enough to enter this thread