Speaker System With Improved Frequency Response

Abstract

A speaker enclosure includes a first set of walls defining a first box, a second set of walls defining a second box disposed within the first box to define an enclosed compartment between the first set of walls and the second set of walls, an aperture located at least one of the second set of walls defining an opening between the internal volume of the second box and the enclosed compartment, and an alternative density transmission medium affixed to one or more surfaces of the first set of walls and/or the second set of walls in the enclosed compartment.

1 . A speaker enclosure, comprising: 
 a first set of walls defining a first box;    a second set of walls defining a second box disposed within the first box to define an enclosed compartment between the first set of walls and the second set of walls;    an aperture located at least one of the second set of walls defining an opening between the internal volume of the second box and the enclosed compartment; and    an alternative density transmission medium affixed to one or more surfaces of the first set of walls and/or the second set of walls in the enclosed compartment.    
   
   
       2 . The apparatus of  claim 1 , wherein surfaces of the first and second set of walls that define boundaries of the enclosed compartment comprise first and second wave-guides.  
   
   
       3 . The apparatus of  claim 2 , further comprising: 
 a termination member at ends of the pair of wave-guides, the termination member having a surface defining a third wave-guide;    wherein the first, second and third wave-guides comprise an embedded acoustic transmission line.    
   
   
       4 . The apparatus of  claim 1 , wherein the alternative density transmission medium comprises a first alternative density transmission medium attached to outer surfaces of the first set of walls and/or a second alternative density transmission medium attached to inner surfaces of the second set of walls to define a channel in the enclosed compartment.  
   
   
       5 . The apparatus of  claim 1 , wherein the enclosed compartment is a sealed compartment with a single opening provided by the aperture.  
   
   
       6 . The apparatus of  claim 1 , wherein the alternative density transmission medium comprises open cell urethane foam.  
   
   
       7 . The apparatus of  claim 1 , further comprising: 
 a port in one of the first set of walls.    
   
   
       8 . The apparatus of  claim 1 , wherein a front wall common to the first and second set of walls includes an opening to receive a loudspeaker.  
   
   
       9 . The apparatus of  claim 1 , wherein at least three of the second set of walls are attached to a front wall of the first box.  
   
   
       10 . A speaker system, comprising: 
 a first cabinet;    a second cabinet disposed within the first cabinet to define an enclosed compartment between inner surfaces of the first cabinet and outer surfaces of the second cabinet;    an aperture in the first cabinet to define an opening that connects the internal volume of the first cabinet with the volume of the enclosed compartment;    an alternative density transmission medium affixed to one or more of the inner surfaces of the first cabinet and/or outer surfaces of the second cabinet; and    a loudspeaker mounted on a wall of the first cabinet.    
   
   
       11 . The system of  claim 10 , wherein the loudspeaker is center mounted along a radial axis of the aperture.  
   
   
       12 . The system of  claim 10 , wherein the alternative density transmission medium comprises open cell foam attached to inner surfaces of the first cabinet and/or outer surfaces of the second cabinet.  
   
   
       13 . The method of  claim 10 , wherein the inner surfaces of the first cabinet and the outer surfaces of the second cabinet that define boundaries of the enclosed compartment comprise first and second wave-guides configured as an embedded acoustic transmission line.  
   
   
       14 . A method of moderating a bias pressure caused by a reflected sound wave in a speaker cabinet, the method comprising: 
 producing a sound wave with a speaker in a first chamber;    directing the sound wave through an aperture from a first chamber to a second chamber of the speaker enclosure;    compressing an alternative density transmission medium in the second chamber with the directed sound wave, the amount of compression varying according to the frequency and the intensity of the sound wave; and    reflecting the sound wave back into the first chamber to moderate the bias pressure in the speaker enclosure.