Patent ID: 7751581
Filing Date: 2010-07-06
Classification: H04R

Abstract:
1. Public address system comprising at least one first loudspeaker at least equipped with one high-frequency sound section for reproducing high-frequency sounds, with one medium-frequency sound section for reproducing medium-frequency sounds, and with a wave expansion guide, said expansion guide comprising an input receiving sound waves coming from a transducer of the high-frequency sound section, and an output in which the sound waves in said expansion guide are distributed in a solid transmission angle, said expansion guide further comprising two input walls, two output walls, and two mobile flaps, the input walls extending in a substantially transverse direction with respect to a first plane, being symmetrical with respect to a median plane perpendicular to the first plane, and mutually forming a first angle, the output walls being respectively connected to the input walls in respective connection zones, forming together a second angle wider than the first angle, and being symmetrical with respect to the median plane, the expansion guide having at least projecting in said first plane, a form opening outwards from said input to said output, and the mobile flaps being moveable by a movement parallel to said first plane, whereby a solid transmission angle is set by moving said mobile flaps, wherein said at least one first loudspeaker comprises two medium-frequency sound sections respectively placed against the two input walls, outside the solid transmission angle, wherein each mobile flap is arranged at least partially inside the second angle, opposite a corresponding output wall, and has a leading edge remote from the output of the expansion guide, and wherein the leading edge of each mobile flap in a first position is spaced from the respective connection zone and is moveable with respect to the respective connection zone, whereby each mobile flap selectively assumes, independently of the other flap, a relatively close or a relatively far position with respect to said corresponding output wall.