Patent ID: 6377696
Filing Date: 2002-04-23
Classification: H04R

Abstract:
A loudspeaker system for reproducing signals between a first, lower frequency and a second, higher frequency of the audio spectrum, the system comprising:a loudspeaker drive unit and a tube acoustically coupled to the rear of the loudspeaker drive unit for leading away and absorbing sound waves produced at the rear of the loudspeaker drive unit, wherein: the tube is acoustically coupled to the loudspeaker drive unit by means of a hollow resonant enclosure and the loudspeaker drive unit is mounted at an aperture in an external wall of the enclosure; the tube communicates with the interior of the enclosure, extends outwardly from the enclosure, and is closed to the external surroundings along its length; there is a significant change in acoustic impedance where the tube communicates with the interior of the enclosure; a crossover network is provided to define the first, lower and second, higher frequencies of sound reproduction of the system; the fundamental resonant frequencies of the enclosure and the tube each lie between the first, lower and second, higher frequencies of sound reproduction of the system but the Helmholtz resonant frequency of the tube, as hereinbefore defined, lies below the first, lower frequency of sound reproduction of the system, and means selected from a group consisting of (i) tapering away of the tube, (ii) closure of the distal end of the tube, and (iii) sound absorbent material are provided to prevent the emergence of sound waves from the distal end of the tube.