The Walsh Tweeter is that inverted gold cone on top of the Infinity box. Essentially a standard tweeter motor of voice coil and magnet attached to an ice cream cone shape of thin metal with damping inside. Invented by Lincoln Walsh, its best known association is with the Ohm Loudspeaker company who acquired the patents. The technology seems rather simple: instead of a traditional horizontal dome acting as a hemispherical piston facing the listener, the Walsh was a vertical pump attempting a 360˚ sphere of high frequencies. Many people still covet this design though it struggled with higher frequencies because of its high mass and large shape.
The technique reminds me of another similar driver approach in the MBL speaker. The MBL incorporates the same idea of a vertical diaphragm attached to the voice coil and magnet of a standard driver. Instead of the ice cream cone shape of the Walsh, a flexible metal balloon is used instead. Here's a picture of an MBL type driver. You can see the spider and magnet of a standard woofer that drives it.
Both are designed to produce radiating 360˚ spheres of sound pressure: the MBL as an expanding and contracting balloon, the Walsh as a rigid pump.
Of course, we understand there's no such thing as a perfect radiator unless we want to get into massless plasma drivers which get us as close to perfect as we're likely to come - though they are as impractical as monkeys typing novels.
A fun bit of audio history.
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