One way of thinking of an audio speaker is like this

M] 3||

The M] is a magnet, and then next to it is a coil (3) near a stiff membrane (||)

What if the stiff membrane was placed between two magnets and two coils

M] 3 || 3 [M

that way the stiff membrane could be driven on both sides, creating greater volume, and possibly enhancing energy efficiency. Greater efficiency at headphones would cause things like iPhones to function longer between electricity refills.
-- beanangel, Feb 10 2017

I don't see where the greater efficiency is coming from.
-- MaxwellBuchanan, Feb 10 2017


Instead of two magnets, one each side, you could use a single double-acting magnet, capable of both attraction and repulsion
-- pocmloc, Feb 11 2017


Dual-voice-coil drivers are real, but a loudspeaker needs to couple the generated mechanical energy into the air somehow, preferably without a magnet getting in the way.
-- Wrongfellow, Feb 11 2017


[+] Magnetic strength decreases with distance. With two magnets, when the push from one drops off, the pull from the other increases. Same effect as two coils bracketing one magnet, but the cone assembly is lighter.

//getting in the way// not an issue; put a cap in the cone, as is done currently.
-- FlyingToaster, Feb 11 2017


Has anyone considered moving the listener back and forth instead of the speaker diaphragm?

//Magnetic strength decreases with distance.// I'm not sure that applies, with the right geometry and over the distances involved.
-- MaxwellBuchanan, Feb 11 2017


The eficience would be the same as a double sized coil inmersed in a larger magnet gap in a standard loudspeaker.. Ohh, Ian already note that. With one coil and one magnet at the front of the device, how do you install a cone or something to convert movement to air pressure ?
-- piluso, Feb 12 2017



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