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Ohm Acoustics developed the first Walsh Driver Speaker in the early seventies with their Ohm A--this speaker took sound reproduction to new heights. Further refinements through the 80's and 90's have produced the current Walsh line of loudspeakers.
The Walsh Series uses a 'Coherent Line Source Driver' (basically an inverted cone driver) with an integral super tweeter. Sound emanates simultaneously from the face of the super tweeter and the top of the inverted cone (this gives the sonic impression of a perfect vertical line source). Once a pair of these speakers is placed correctly in a room they supply unrivaled soundstage and imaging, equaled only by electrostatic speakers, or exotic custom horns.
Later, less expensive, Ohm speakers didn't actually use a Walsh driver, but rather an ordinary woofer facing downward and a regular dome tweeter mounted atop the woofer. The woofer and tweeter were contained in a factory sealed can about 8" in diameter and 10" tall to disquise the fact that the technology was actually rather ordinary. I worked for a company that sold Ohm speakers and was able to open a defective one and inspect its inner workings.
The Walsh driver is one way to achieve the "fountain of sound" dispersion. A less expensive one used by humble Zenith Allegro systems was to use a plastic cone and na upward firing driver. It was dropped because in real rooms this does not work well for stereo.