Speaker cabinet with tuned stress elements

Abstract

A speaker cabinet has front and back walls and side walls defining a sound chamber, and a location for supporting at least one speaker in one of the walls. Thin metallic stress elements extend between and are connected to selected pairs of walls, and are loaded undertensile stress so as to tune them to desired resonant frequencies. The tuned stress elements vibrate in response to excitation by sound waves emitted from the speaker, thus producing additional sound which enhances the sound from the speaker. Tensioning means provide for selectively adjusting the tensile stress and resonant frequencies of the stress elements and, consequently, the character of the sound produced by vibration of the stress elements.

What is claimed is:  
     
         1 . A speaker cabinet having: 
 (a) a top panel and a bottom panel, and a plurality of walls disposed between and connecting to the top panel and bottom panel, said top panel, bottom panel, and walls defining a sound chamber;    (b) means for supporting a speaker in one of the walls; and    (c) one or more elongate stress elements passing through the sound chamber and extending between two of the walls, each stress element having a first end and a second end;    wherein:    (d) the first and second ends of each stress element are connected, respectively, to the walls between which the stress element extends; and    (e) each stress element is loaded under longitudinal tensile stress.    
     
     
         2 . The speaker cabinet of  claim 1 , wherein the walls include a front wall and a back wall, plus two side walls each disposed between and at substantially right angles to said front wall and back wall.  
     
     
         3 . The speaker cabinet of  claim 2 , wherein the speaker support means is located in the front wall, and in which one or more stress elements extend between the front wall and the back wall.  
     
     
         4 . The speaker cabinet of  claim 3 , wherein the one or more stress elements extend between the front wall and the back wall.  
     
     
         5 . The speaker cabinet of  claim 4 , wherein the stress elements are disposed substantially parallel to each other and substantially normal to the front wall and the back wall.  
     
     
         6 . The speaker cabinet of  claim 4 , further having one or more stress elements extending between the side walls.  
     
     
         7 . The speaker cabinet of  claim 6 , wherein the stress elements extending between the side walls are disposed substantially parallel to each other and substantially normal to the side walls.  
     
     
         8 . The speaker cabinet of  claim 1 , wherein at least one of the walls is curvilinear.  
     
     
         9 . The speaker cabinet of  claim 1 , wherein the stress elements are made substantially of metal.  
     
     
         10 . The speaker cabinet of  claim 9 , wherein the stress elements are made substantially of a metal selected from the group consisting of steel and copper.  
     
     
         11 . The speaker cabinet of  claim 1 , wherein one wall defines one or more ports.  
     
     
         12 . The speaker cabinet of  claim 1 , further comprising tensioning means for varying the tensile stress in each stress element.  
     
     
         13 . The speaker cabinet of  claim 12 , wherein one end of each stress element is threaded, and wherein the tensioning means comprises a threaded sleeve engageable with the threads of the stress element, said sleeve being rotatably mounted in the wall corresponding to the threaded end of the stress element, said sleeve also having tool-engagement means whereby the sleeve may be rotated relative to the stress element.  
     
     
         14 . The speaker cabinet of  claim 1 , wherein each stress element is tensioned such that its resonant frequency is in the range between about 200 Hz and about 600 Hz.  
     
     
         15 . The speaker cabinet of  claim 1 , wherein at least one wall is fabricated from a material selected from the group consisting of lumber and wood particle board.  
     
     
         16 . The speaker cabinet of  claim 1 , wherein at least one wall is fabricated from a thermoplastic material.  
     
     
         17 . A speaker cabinet having: 
 (a) a top panel and a bottom panel, a front wall and a back wall, plus two side walls each disposed between and at substantially right angles to said front wall and back wall, wherein: 
 (i) the front wall, back wall, and side walls are disposed between and are connected to said top panel and bottom panel;  
 (ii) the top panel, bottom panel, front wall, back wall, and side walls define a sound chamber; and  
 (iii) the front wall defines an opening for a speaker, and includes means for supporting said speaker therein;  
   (b) a first plurality of elongate metallic stress elements passing through the sound chamber and extending between the frontwall and the back wall; and    (c) tensioning means comprising, for each stress element, a threaded sleeve engageable with the threads of the stress element, said sleeve being rotatably mounted in the wall corresponding to the threaded end of the stress element, said sleeve also having tool-engagement means whereby the sleeve may be rotated relative to the stress element;    wherein:    (d) the first and second ends of each stress element are connected, respectively, to the front, rear, or side walls between which the stress element extends;    (e) the stress elements are substantially parallel to each other and substantially normal to the front wall and the back wall; and    (f) each stress element is loaded under longitudinal tensile stress such that its resonant frequency is in the range between about 200 Hz and about 600 Hz.    
     
     
         18 . The speaker cabinet of  claim 17 , further comprising a second plurality of elongate stress elements passing through the sound chamber and extending between the side walls, each stress element having a first end and a threaded second end, and wherein the second plurality of stress elements are substantially parallel to each other and substantially normal to the side walls.  
     
     
         19 . The speaker cabinet of  claim 17 , wherein the stress elements are made substantially of a metal selected from the group consisting of steel and copper.  
     
     
         20 . The speaker cabinet of  claim 17 , wherein at least one wall is fabricated from a material selected from the group consisting of lumber and wood particle board, and wherein one wall defines one or more ports.