GB1018129A - Loudspeaker assemblies - Google Patents

Abstract

1,018,129. Loud-speaker enclosures. A. M. QUENNELL. Sept. 15, 1964 [Sept. 23, 1963], No. 37399/63. Headings H4J and H4X. A loud-speaker enclosure comprises two chambers 12, 13 (Fig. 1) interconnected by a duct 15 in a partition wall 11. A loudspeaker 14 is mounted in an aperture in the larger chamber 12. An hermetically sealed combination is thereby provided in which the air space within the chamber 12 has a volume substantially twice that of the chamber 13. The volume of the chamber 13 and the dimensions of the duct 15 are so chosen as to afford to the chamber 13 a resonant frequency at least as low as the lower limit of audibility (which may be taken as 30 c/s.). The resonant frequency of the assembly substantially equals the resonant frequency of the chamber 13 and the response curve of the assembly exhibits a rising characteristic to the lower limit of audibility. By choice of the cross-sectional area or length of the duct 15, the response of the assembly can be spread over a wide or narrow range of frequencies. The duct is of rectangular or circular cross-section. The resonant frequency of the assembly is preferably below the resonant frequency of the loudspeaker 14. The chambers 12, 13 contain damping material. The loudspeaker 14 may be mounted in the upper wall of the enclosure (Fig. 2, not shown).