Patent ID: 7708112
Filing Date: 2010-05-04
Classification: G10K,H04R

Abstract:
1. An acoustic horn for a loudspeaker comprising: a hollow member having an inlet opening and an outlet opening larger than said inlet opening at opposite longitudinal ends, respectively, of said hollow member, wherein said hollow member has an interior wall defining a longitudinally directed conduit open to said inlet and outlet openings at either end, respectively, of said conduit, said conduit having a progressively increasing cross-sectional area along and transverse to a longitudinal axis from the inlet opening to the outlet opening, wherein the inlet-opening end of said conduit is adapted to be acoustically coupled to the front side of a diaphragm or the principle mode output of an electrodynamic audio transducer, and further wherein said interior wall defines progressively divergent waveguide boundaries for cross-sectional expansion of any sound wave passing from the inlet opening to the outlet opening; and, a body of porous refractory material contained in said conduit, said porous material being substantially transparent but partially absorptive to any sound wave directed into said material, wherein the volume of said body is sized to fill more than 20% of the volume of said conduit, and further wherein said body is dimensioned to completely span a cross-sectional area of the conduit between said waveguide boundaries at a longitudinal position of said body within said conduit, and has a convex shape on a surface of the body that faces the outlet opening.