Abstract:
The invention relates generally to the field of audio loudspeaker enclosures, and more particularly to a method of mounting the internal components in the loudspeaker so as to control the loudspeaker output. Specifically a mounting structure and method for mounting the loudspeaker horn to its associated compression driver are disclosed. The mounting structure allows the directivity of the loudspeaker output, and the frequency/phase control of the loudspeaker, output to be controlled by the spatial arrangement of these components in the loudspeaker enclosure.

Description:
This application claims the benefit of U.S. Provisional Application No. 60/379,329 filed May 9, 2002. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Technical Field 
     The invention relates generally to a method of mounting internal components in a loudspeaker to control the loudspeaker output. Specifically, a mounting structure and method for mounting the loudspeaker horn to its associated compression driver is disclosed, where the horn and the compression driver are mounted on the same interior baffle within the loudspeaker enclosure. 
     2. Related Art 
     A long-standing problem in the design of audio loudspeakers relates to the loudspeaker enclosure and the manner and location of mounting components within the enclosure. Known loudspeaker enclosures typically include one or more low frequency subassemblies and a single high frequency speaker subassembly. Multiple numbers of these loudspeaker enclosures (i.e., typically four or more), in combination, are required to produce an acoustic effect which has limited acoustical interference, especially between outputs of the low frequency subassemblies and the high frequency speaker subassemblies. Conventional loudspeaker constructions also typically produce an unbalanced power response at near- to mid-field distances from the loudspeaker enclosure. Further, the spatial separation between the one or more low frequency subassemblies and the single high frequency speaker subassembly, within a particular enclosure, that is required to produce a desired level of acoustic quality, necessitates a relatively large-sized loudspeaker enclosure. This loudspeaker enclosure may not be physically suitable for particular locations, so that a reduced loudspeaker enclosure with attendant reduced acoustical qualities may be the resulting but unacceptable compromise. 
     Thus, a need exists for a loudspeaker structure and component mounting method which produces a loudspeaker enclosure yielding the acoustic qualities of a combination of loudspeaker enclosures larger in a single, smaller enclosure. A further need exists for a loudspeaker enclosure which accomplishes a given acoustic criteria with a smaller number of components, in the smaller enclosure. 
     SUMMARY OF THE INVENTION 
     To overcome the above deficiencies, the present invention provides a structure and related method of producing a loudspeaker enclosure which a loudspeaker structure and component mounting method which produces a loudspeaker enclosure yielding the acoustic qualities of a larger enclosure in a relatively smaller enclosure. The present invention also accomplishes this loudspeaker with a smaller number of components. 
     In a first general aspect, the present invention provides an audio loudspeaker assembly comprising: an enclosure; an inner baffle structure mounted inside said enclosure and operatively attached to said enclosure; at least one low frequency subassembly operatively mounted on said baffle structure, said low frequency subassembly having a low frequency horn; and a high frequency subassembly operatively mounted on said baffle structure, said high frequency subassembly having a high frequency horn. 
     In a second general aspect, the present invention provides a method of constructing an audio loudspeaker, said method comprising: providing an enclosure; providing an inner baffle structure mounted inside said enclosure and operatively attached to said enclosure; providing at least one low frequency subassembly operatively mounted on said baffle structure, said low frequency subassembly having a low frequency horn front end; and providing a high frequency subassembly operatively mounted on said baffle structure, said high frequency subassembly having a high frequency horn front end. 
     In a third general aspect, the present invention provides an audio loudspeaker system comprising: a primary control system for controlling the directivity of the loudspeaker system, said primary control system responsive to a broadband directivity characteristic factor, said directivity factor representative of the directional capability of the audio output of the loudspeaker system; and wherein said directivity factor is directly proportional to the frequency of operation across the audible frequency range, producing a linear directivity characteristic. 
     In a fourth general aspect, the present invention provides a method of controlling directivity in a loudspeaker system, said method comprising: providing a loudspeaker enclosure, said loudspeaker enclosure including a high frequency horn and at least one low frequency horn; mounting said high frequency horn and said low frequency horn on the same baffle with said loudspeaker enclosure; and providing a primary control system for controlling the directivity of the loudspeaker system, said primary control system operationally coupled to said low frequency horn and said high frequency horn. 
     In a fifth general aspect, the present invention provides an acoustic performance system comprising: an venue area designated for an acoustic performance; one or more loudspeaker enclosures distributed in said venue area, said loudspeaker enclosures adapted to provide amplification and distribution of said acoustic performance; at least one of said loudspeaker enclosures further comprising; a baffle structure mounted inside said enclosure and operatively attached to said outer enclosure; at least one low frequency subassembly operatively mounted on said baffle structure, said low frequency subassembly having a low frequency horn front end; and a high frequency subassembly operatively mounted on said baffle structure, said high frequency subassembly having a high frequency horn front end. 
     The foregoing and other features and advantages of the invention will be apparent from the following more particular description of embodiments of the invention. It is to be understood that both the foregoing general description and the following detailed description are exemplary, but are not restrictive, of the invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The features of the present invention will best be understood from a detailed description of the invention and an embodiment thereof selected for the purposes of illustration and shown in the accompanying drawings in which: 
         FIG. 1  is a schematic drawing of a loudspeaker enclosure according to the present invention; 
         FIG. 2  is a schematic drawing of a high frequency subassembly according to the present invention; 
         FIG. 3  is an exploded view of a partial loudspeaker assembly according to the present invention; 
         FIG. 4  is a is another view of the partial loudspeaker assembly of  FIG. 3 ; 
         FIG. 5  is a partially exploded view of a loudspeaker enclosure according to the present invention; 
         FIG. 6  is a schematic drawing of a loudspeaker and its associated destructive interference pattern according to the present invention; 
         FIG. 7  is a schematic drawing of a loudspeaker and its associated power response according to the present invention; 
         FIG. 8  is a graphical representation of the comparison of different directivity characteristics; and 
         FIG. 9  is a graphical representation of the comparison of different beamwidth characteristics. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Although certain embodiments of the present invention will be shown and described in detail, it should be understood that various changes and modifications may be made without departing from the scope of the appended claims. The scope of the present invention will in no way be limited to the number of constituting components, the materials thereof, the shapes thereof, the relative arrangement thereof, etc., and are disclosed simply as an example of an embodiment. The features and advantages of the present invention are illustrated in detail in the accompanying drawings, wherein like reference numerals refer to like elements throughout the drawings. 
     The invention described herein provides a loudspeaker enclosure wherein a high frequency subassembly and one or more low frequency assemblies are mounted on a common component, which is typically a baffle structure located inside the overall loudspeaker outer enclosure. Referring to  FIG. 1 , this arrangement is shown in the schematic drawing. A loudspeaker system  100  includes an outer enclosure  102 , having front and back walls, and sidewalls. Inside the outer enclosure, an inner baffle structure  101  is mounted. The inner baffle structure  101  is securely attached to said outer enclosure  102 . A representative low frequency subassembly  106  is mounted on the rear side of the baffle structure  101  via its low frequency horn. A high frequency subassembly  103  is mounted on baffle structure  101  so that the motor portion  104  of the high frequency subassembly  103  is situated to the rear of baffle structure  101 , while the horn  105  is located to the front of the baffle structure  101 . 
       FIG. 2  shows a more detailed schematic drawing of high frequency subassembly  103  from the front perspective. Baffle structure  101  supports, on one side, driver motor  106 . Mounted on driver motor  106  is the motor diaphragm  207 , which is attached by screws  208  or other suitable fastening means. Horn  105  is mounted to the baffle structure  101  from the other side of the baffle structure  101 . Horn mounting flange  220  includes through holes  223  which align with mounting screws  209  of the driver motor  106 . This alignment is facilitated when the horn mounting flange  220  is rotatably mounted to said baffle structure  101 . An embodiment of the horn  105  has a lower cutoff frequency of approximately 700 Hz. Mounting screws  209  are received by machine nuts  210  to securely attach the driver motor  106  to the horn  105 , and the high frequency subassembly  103  to the baffle structure  101 . Proper alignment of the driver motor  106  to the horn  105  also ensures proper alignment of the portions of the waveguide  215  which are located in the driver motor  106  and the starting throat area of horn  105 . Proper alignment occurs when the central, longitudinal axes of the horn and of the waveguide coincide. 
       FIG. 3  illustrates an exploded view of a partial loudspeaker assembly  300  viewed from the front of the assembly. Baffle structure  301  includes two openings  302 ,  306  intended to receive low frequency subassemblies (not shown). Through hole  305  is intended to receive both horn  304  and driver motor  303  which are aligned and secured about through hole  305  with fasteners  307  or the like.  FIG. 4  presents another view of the partial loudspeaker assembly of  FIG. 3 , from the rear perspective. 
       FIG. 5  is a partially exploded view of an acoustic system  500  including loudspeaker enclosure  501  according to one embodiment of the present invention. The spatial relationship of the low frequency subassemblies  502 ,  506  to the high frequency subassembly comprising a driver motor  303  and a horn  304 , when these components are mounted on a baffle structure  301 . 
       FIG. 6  is a schematic drawing of a loudspeaker assembly  600  according to an embodiment of the present invention, and its associated destructive interference pattern  609 . Loudspeaker  601  includes a baffle structure  604 , to which are mounted low frequency subassemblies  602 ,  603  and high frequency subassembly  605 . The beam pattern  609  indicates reduced off-axis destructive interference centered about location X, and caused by the locations of low frequency wave patterns following a first axis  607  and a second axis  608 , relative to a central high frequency assembly  605 . 
       FIG. 7  is a schematic drawing of a loudspeaker and its associated power response according to an embodiment of the present invention. The loudspeaker assembly  701  produces a balanced power response at near to mid-field distances from the loudspeaker enclosure. This property is depicted in  FIG. 7 , where an acoustic system  700  includes the loudspeaker assembly  701 , a high frequency subassembly  702 , two low frequency subassemblies  703 ,  704 , and the associated low frequency  705  and high frequency  706  beam patterns produced by the respective low and high frequency subassemblies  703 ,  704 ,  702 , respectively. Note that the ellipses formed by the low frequency  705  and high frequency  706  beam patterns have large portions where they basically coincide. Portion  711  represents the high frequency excess portion of the high frequency beam 706 portion. 
       FIG. 8  is a graphical representation of the comparison of different directivity characteristics of the industry standard, an ideal characteristic, and a characteristic produced by an embodiment of the present invention. This embodiment of the present invention comprises two equivalent compact 15 inch two-way mid-high frequency loudspeakers having a 2 KHz crossover point, supplemented by a 18 inch subwoofer loudspeaker. Graph  800  shows the ideal characteristic as trace  803 . Trace  801  represents the industry standard. Trace  802  represents the directivity characteristic obtained from the embodiment of the invention. 
       FIG. 9  is a graphical representation of the comparison of different beam width characteristics of an embodiment of the present invention compared to the related art. Graph  900  shows the ideal characteristic as trace  903 . Trace  901  represents the related art. 
     The foregoing description of the present invention has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form disclosed or to the materials in which the form may be embodied, and many modifications and variations are possible in light of the above teaching. Such modifications and variations that may be apparent to a person skilled in the art are intended to be included within the scope of this invention as defined by the accompanying claims.