Patent ID: 6950530

Claim:
A directional loudspeaker unit for reproducing mid-range audio frequencies, comprising a cone loudspeaker and, disposed forwardly of the surface of the cone of the loudspeaker, a phase plug and a horn, wherein the phase plug is arranged co-axially on the axis of the cone and has a generally toroidal shape, the phase plug having a central aperture and forming with the horn an annular aperture, the central aperture forming a first sound path predominantly carrying high-frequency sound from a central portion of the cone and the annular aperture forming a second sound path of different shape to the first said path and predominantly carrying low-frequency sound from a surrounding annular portion of the cone, the central and annular portions of the cone being driven by a single driving means, the separation of the sound according to frequency and path shape in the respective first and second sound paths being such that a generally constant directivity is attained by sound leaving the mouth of the horn.