Abstract:
The loudspeaker and method provide a driver of a loudspeaker that is movable parallel to an axis of movement through a center of the driver to produce sound waves. The driver is aligned with the driver plane orthogonal to the axis of movement. The driver plane is at a non-zero acute angle to a support plane. A reflector is mounted facing a diaphragm of the driver for reflecting sound waves from the driver. The reflector is configured relative to the driver such that reflected sound energy is greatest in a selected direction from a front of the reflector and the driver, and diminishes a progressively larger angle from the selected direction. The selected direction diverges from the driver plane.

Description:
This application claims benefit of 60/361,355 Mar. 5, 2002. 
    
    
     FIELD OF THE INVENTION 
     This invention relates to audio loudspeakers. 
     BACKGROUND OF THE INVENTION 
     Omni-directional loudspeakers, which transmit sound in all directions are well-known. Typically, such loudspeakers have an axis along which at least one driver is mounted such that the driver&#39;s cone moves in an axial direction. Typically the axial direction is normal to the floor or ground of the area in which the loudspeaker is used. The driver generates sound waves which propagate either upwards away from or downwards towards the floor or ground. A sound reflector is positioned co-axially with the driver to reflect the sound waves to produce reflected waves which propagate away from the loudspeaker with equal strength in all directions. Such omni-directional speakers desirably provide a wide sound field which allows a person positioned in any direction around the loudspeaker to hear wide bandwidth sound produced by the loudspeaker. 
     Modern sound systems, including so-called home theatre systems, often incorporate 5 or more loudspeakers which are positioned at various locations within a listening room. The loudspeakers are preferably configured and positioned to provide a balanced sound field in a listening area. To increase the size of the listening area in which a relatively flat frequency response is achieved, it is desirable to use loudspeakers with a relatively wide sound field. To enhance the balance of the sound field at the listening position, it is desirable to control the shape of the sound field produced by any particular loudspeaker. To achieve a wide sound field from a loudspeaker, it is desirable to attain a wide dispersion pattern across a wide portion of the audible frequency range. 
     Accordingly, it is desirable to provide a loudspeaker that allows the wide sound field characteristics of an omni-directional loudspeaker to be shaped. 
     SUMMARY OF THE INVENTION 
     An object of an aspect of the present invention is to provide an improved loudspeaker. 
     In accordance with this aspect of the present invention there is provided a loudspeaker comprising: (a) a base defining a support plane, the base being operable to support the loudspeaker relative to surface; (b) a driver mounted to the base, the driver being movable parallel to a direction of movement to produce sound waves; and, (c) a reflecting surface mounted a diaphragm of the driver for reflecting sound waves from the driver. The reflecting surface is configured relative to the driver such that the reflected sound energy is greatest in a selected direction from a front of the reflecting surface and the driver, and diminishes at progressively larger angles from the seleted direction. The driver is aligned with a driver plane orthogonal to the axis of movement, the driver plane being at a non-zero acute angle to the external support plane. The selected direction diverges from the driver plane. 
     An object of a second aspect of the present invention is to provide an improved loudspeaker. 
     In accordance with this second aspect of the present invention there is provided a loudspeaker comprising: (a) a base defining a support plane, the base being operable support the loudspeaker relative to surface; (b) an input terminal for receiving an audio signal and a cross-over connected to the input terminal for dividing the audio signal into a plurality of component signals; (c) a first driver mounted to the base and linked to the cross-over to receive a first component signal in the plurality of signals, the first driver being drivable by the first component signal to move parallel to a first axis of movement through a center of the first-driver to produce sound waves; (d) a first reflector mounted facing a first diaphragm of the first driver for reflecting sound waves from the first driver, the first reflector being configured relative to the first driver such that reflected sound energy is greatest in a first selected direction from a front of the first reflector and the first driver, and diminishes at progressively larger angles from the first selected direction; and, (e) at least one of a second driver for producing higher frequency sound waves than the sound waves produced by the first driver and a third driver for producing lower frequency sound waves than the sound waves produced by the first driver, the at least one of the second driver and the third driver being mounted to the base and linked to the cross-over to receive at least one component signal in the plurality of component signals from the crossover. The first driver is aligned with a first driver plane orthogonal to the axis of movement, the first driver plane being at a non-zero acute angle to the support plane. The first selected direction diverges from the first driver plane. 
     An object of a third aspect of the present invention is to provide an improved loudspeaker. 
     In accordance with this third aspect of the present invention there is provided a method of directing sound waves from a driver of a loudspeaker. The method comprises: (a) providing an audio signal to the driver, the driver being movable parallel to an axis of movement through a center of the driver to produce sound waves based on the audio signal; (b) orienting the driver such that a driver plane orthogonal to the axis of movement is at a selected angle of inclination relative to a horizontal plane, the selected angle of inclination being a non-zero acute angle; and, (c) reflecting sound waves from the driver such that reflected sound energy is greatest in a selected direction from a front of the driver and diminishes at progressively larger angles from the selected direction. The selected direction diverges from the driver plane. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       A preferred embodiment of the present invention will now be described in detail with reference to the drawings, in which: 
         FIG. 1  is a perspective drawing of a loudspeaker according to a first embodiment of the present invention; 
         FIG. 2  is a cross-sectional side view of the loudspeaker of  FIG. 1 ; 
         FIG. 3  is a detailed cross-sectional view of a sound reflector and a driver of the loudspeaker of  FIG. 1 ; 
         FIG. 4  is a top view of the loudspeaker of  FIG. 1 ; 
         FIG. 5  is a perspective drawing of a loudspeaker according to a second embodiment of the present invention; 
         FIG. 6  is a cross-sectional side view of the loudspeaker of  FIG. 5 ; 
         FIG. 7  is a side view of the loudspeaker of  FIG. 5  illustrating a sound field; 
         FIG. 8  illustrates the use of a multiple speakers according to the present invention; 
         FIG. 9  is a cross-sectional side view of a loudspeaker according to a third embodiment of the present invention; 
         FIG. 10  is a perspective view of a loudspeaker according to a fourth embodiment of the present invention; and 
         FIG. 11  is a cross-sectional side view of a loudspeaker according to a fifth embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Human hearing is at its most sensitive to sound within a fairly narrow region between 2 kHz and 5 kHz. This is also the region where our brains perform much of the processing needed to localize or determine the position or origin of sound. 
     In audio systems, multiple loudspeakers are used to recreate a three-dimensional recorded event. That is, a three-dimensional effect is created through the position, intensity and time delay between the two or more channels. Our brains are able to recreate a sense of space and size because of this, as well as a sense of the reflections that occur within a typical room. For example, listening to a symphony orchestra in a very good concert hall, one hears sound that has a very high proportion of reflected information. Typically, 70% of the audio information will be reflected, and only 30% will be direct sound from the performance on stage. 
     If we listen to a typical speaker with drivers on the vertical plane, much of the sound, particularly at high frequencies, will be directed right at the listener and the reflected content will be minimal. This lack of reflected information, compared to what happens in reality, would reduce the perceived size of the sound—the “soundstage”. However, because of the large amount of direct signal between 2 kHz to 5 kHz, a speaker with drivers on the vertical plane will produce tightly defined acoustic images. In the other extreme, in a prior art omni directional speaker with a reflector above a driver on the horizontal plane, the ratio of reflected information to direct information from the speaker will be very high. As a result, a large sense of space, such as in a concert hall, will be created in the brain. However, as very little direct signal reaches the listener, particularly in the 2 kHz to 5 kHz region, poorly defined images that do not mimic reality will be created in the brain. 
     Embodiments of the present invention permit the ratio of direct signal to reflected signal to be varied, particularly at frequencies between 2 kHz to 5 kHz, which is the upper operating range of a woofer. By doing so, the reflected information required to produce a large soundstage can be retained. At the same time, by also retaining a sufficient amount of direct signal, the image created by the sound can be focused to better duplicate the sound of a live performance. 
     Reference is first made to  FIG. 1 , which illustrates a loudspeaker  20  according to a first embodiment of the present invention. Loudspeaker  20  has a housing  22 , a driver  24 , a housing baffle  26 , input terminals  28 ,  30  ( FIG. 2 ) and a sound reflector  32 . 
     Housing  22  has a base  40 , which also defines the base  42  of loudspeaker  20 . Baffle  26  is mounted on the top  44  of housing  22  using several screws  46  ( FIG. 2 ). Alternatively, baffle  26  may be mounted to housing  22  using a friction mount, another type of fastener or any other method. Driver  24  is mounted in an opening  48  in baffle  26 . Driver  24  is mounted such that its cone  50  faces out from the top of baffle  26 . Sound reflector  32  is formed integrally with baffle  26  and is spaced apart from baffle  26  by support  54 , which is also formed integrally with baffle  26 . In another embodiment of the present invention, sound reflector  32  and support  54  may be formed separately from baffle  26  and may be assembled with baffle  26  using one or more fasteners and/or an adhesive. 
     Sound reflector  32  is positioned above driver  24  and has a sound reflecting surface  58  which faces the cone  50  of driver  24 . 
     Terminals  28 ,  30  are mounted on a rear side of housing  22 . Terminals  28 ,  30  may be any type of mounting terminals suitable for attaching audio cables (not shown). Terminals  28 ,  30  are coupled to driver  24  by wires  60 ,  62  ( FIG. 2 ). 
     Referring next to  FIG. 2 , the base  42  of loudspeaker  20  generally defines a base plane  68 , which in operation rests on external support plane, provided by, for example, a floor or a bookshelf. The top edge of cone  50  defines a driver plane  70 . Driver plane  70  is at an angle  71  to base plane  68 . 
     In use, loudspeaker  20  may be positioned so that base plane  68  is substantially parallel to the floor or ground (not shown) in the area where loudspeaker  20  is used. As a result, driver plane  70  will typically not be parallel to the floor or ground. Alternatively, loudspeaker  20  may be suspended from a ceiling so that its base is parallel to the floor or ground, or it may be mounted with its base or back against a wall. 
     In use, loudspeaker  20  receives an audio signal at terminals  28 ,  30  from a signal source (not shown) in known manner. The signal source may be an audio receiver or amplifier. A skilled person will understand the operation and connection of an appropriate audio source and this is not further described here. 
     Reference is next made to  FIG. 3 , which is an enlarged view of driver  24  and sound reflector  32 . Driver  24  receives the audio signal through wires  60 ,  62  ( FIG. 2 ) and causes its cone  50  to move in an axial direction  66 , which will typically be normal to driver plane  70 . As cone  50  moves, it creates sound waves  74 . Sound waves  74  have a range of frequency components with the specific range depending on the selection of driver  24 . Higher frequency components, and particularly those with a wavelength shorter than the diameter of cone  50 , are propagated in a direction generally normal to driver plane  70 , in the direction of reflecting surface  58 . As sound waves  74  strike reflecting surface  58 , they are reflected outwardly from loudspeaker  20  as sound waves  76 . Although sound waves  76  are shown propagating from loudspeaker towards the front and rear of loudspeaker  20 , sound waves  76  will actually propagate away from loudspeaker  20  in all directions. 
     Reference is additionally made to  FIG. 4 . Reflector  32  is positioned above driver  24  such that sound waves  74  are reflected as sound waves  76  unequally. Relatively large portions of sound waves  76  are reflected in direction  77  from the front of loudspeaker  20 . This means that a relatively large portion of the sound energy produced by driver  24  is directed outward from the loudspeaker  20  in direction  77 . 
     Progressively less of sound waves  76  (and progressively less of the sound energy produced by sound energy produced by loudspeaker  20 ) are reflected in each direction at progressively larger angles from the front of loudspeaker  20 . The smallest portions of sound waves  76  are reflected in direction  78  towards the rear of loudspeaker  20 . Curve  79  illustrates the relative strength of the sound waves  76  reflected in all directions away from loudspeaker  20 . 
     Reference is again made to  FIG. 3 . The relative amplitude of sound waves  76  propagated away from loudspeaker  20  in any direction depends on the shape and size of reflector  32 , the position of reflector  32  with respect to driver  24  and the size and shape of driver  24 . The reflecting surface  58  of sound reflector  32  has a compound surface with three flat sections  80 ,  82  and  84  separated by curved sections  86  and  88 . Curved section  86  has a smaller radius of curvature than curved section  88 . 
     The particular size and shape of reflecting surface  58  in any particular embodiment of a loudspeaker  20  according to the present invention will depend on the frequency response of the driver  24  and on the frequency response desired for the loudspeaker  20 . Driver  24  of this exemplary loudspeaker  20  is a full range loudspeaker chosen to cover a large portion of the audible frequency spectrum. The shape of reflection surface  58  has been found to provide a relatively flat frequency response for loudspeaker  20 , when used with such a loudspeaker. If a different frequency response or dispersion pattern is desired for loudspeaker  20 , a differently shaped reflection surface may be used. For example, a parabolic, elliptical, hyperbolic or circular reflection surface may be used in alternative embodiments. 
     A driver  24  of any shape or size may be used with the present invention. If a larger driver  24  is used, a larger proportion of the generated sound waves will be directional. The size of sound reflector  74 ,  76  may need to be increased, if it is desired that the reflector  32  effectively redirect the large range of directional frequency components. 
     Reference is made to  FIG. 4 . The degree to which reflector  32  is effective in reflecting sound waves  74  also depends on the frequency of the sound waves  74 . It is well known-that low frequency audio waves are less directional than higher frequency audio waves. This means that a low frequency sound diverges more widely and propagates in virtually all directions (in three dimensions) away from its source (typically a loudspeaker). A high frequency sound on the other hand is less divergent and propagates in a comparatively narrow or focused direction compared to the low frequency sound. In the absence of sound reflector  32 , low frequency sounds produced by driver  24  would propagate widely in all directions away from loudspeaker  20 . However, high frequency sounds would travel upwards along line  66  ( FIG. 3 ) and would diverge much more narrowly. 
     High frequency sound waves are more easily reflected by obstacles in their paths, particularly when the obstacle is larger than the wavelength of the sound waves. In contrast, lower frequency sound waves are affected to a lesser degree by obstacles in their path. This means that higher frequency components of sound waves  74  ( FIG. 3 ) will be reflected by sound reflector  32  more than lower frequency components. Sound reflector  32  is sized so that its diameter  90  is larger than the wavelength of frequency components that sound reflector  32  is intended to reflect. 
     As noted above, driver  24  is selected to generate sound waves  74  with a broad range of frequency components. Curve  79  illustrates the shape of the sound field produced by loudspeaker  20  for relatively high audio frequencies. Curve  96  illustrates the shape of the sound field produced by loudspeaker  20  for mid-range audio frequencies. Curve  98  illustrates the shape of the sound field produced by loudspeaker  20  for relatively low audio frequencies. Curves  79 ,  96  and  98  are merely illustrative, are not to scale and do not define boundaries of the sound field at each frequency range. They are intended to illustrate the general shape of wave propagation in each frequency range. Curves  79 ,  96  and  98  illustrate that the total sound field produced by loudspeaker  20  will have more directional higher frequency components and less directional low frequency components. The sound field produced by loudspeaker  20  will radiate away from loudspeaker  20  in three dimensions. The vertical shape of the sound field at frequency range is similar to its horizontal dimension. Thus, curves  79 ,  96  and  98  illustrate the cross-section of the sound field in each corresponding frequency range. 
     The shape of reflecting surface  58  has been found to give a relatively flat frequency response for loudspeaker  20  across a wide frequency range, when measured from a horizontal position at about the height of loudspeaker  20 . Loudspeaker  20  provides a large three-dimensional listening area at its front side and makes efficient use of the sound energy generated by driver  24  in doing so. 
     In this exemplary loudspeaker  20 , the angle  71  between base plane  68  and driver plane  70  is 25 degrees. In other embodiments of the present invention, this angle is 30 degrees. This angle is chosen to provide a flat driver frequency response along axis  66  ( FIG. 3 ). In other embodiments of the present invention, this angle may be between 5 and 85 degrees, between 10 degrees and 80 degrees, or between 20 and 35 degrees. 
     A sound reflector plane  90  may be defined for sound reflector  32  across the top of reflecting surface  58 . The angle  92  between sound reflector plane  33  and driver plane  70  is chosen based on the sound dispersion pattern that is desired to be produced by loudspeaker  20 . The desirable sound dispersion pattern will depend on the application of the loudspeaker  20 . For example, depending on the room (or type of room) in which the loudspeaker  20  is expected to be used, different sound reflections will occur at the room&#39;s boundaries (i.e. the walls defining the room). Typically, loudspeaker  20  will be placed with its rear close to the wall or the back of a bookshelf. By angling sound reflector  32  so that its front side  32   f  is angled downwards, as in the exemplary loudspeaker  20 , the sound waves directed from the front of loudspeaker  20  will be concentrated towards a listener in front of the loudspeaker  20  at generally the same height as the loudspeaker  20 . At the same time, the sound waves reflected from the back of the loudspeaker  20  will have a slight upwards direction and will bounce off the wall or bookshelf and be reflected frontwards and upwards at a generally higher height than the sound waves reflected from the front of loudspeaker  20 . This contributes to a spacious sound field. Angle  92  affects the vertical response characteristics of a loudspeaker made according to the present invention. A skilled person will be capable of selecting an appropriate angle to provide a desired sound filed characteristic. 
     Sound reflector  32  operates to shape both the horizontal and vertical shape of the sound field produced by loudspeaker  20 . The shape and the angle of sound reflector  32  relative to driver plane  70  have been described above. As sound waves  74  produced by driver  24  encounter sound reflector  32 , some of them will actually wrap around sound reflector  32  and form diffracted sound waves  81  ( FIGS. 2 and 3 ) above sound reflector  32 . Higher frequency components of sound waves  74  that have a wavelength smaller than the diameter of sound reflector  32  will be both diffracted and reflected by sound reflector  32  as sound waves  81  and as sound waves  76 . The proportion of the sound waves  74  that will be diffracted increases as the size of the sound reflector  32  is reduced. Sound reflector  32  may be sized to provide a desired sound field may be produced in both the horizontal and vertical directions in the listening area. 
     As noted above, loudspeaker  20  is provided with a driver  24  selected to produce sound with a wide frequency range in response to an audio signal. It may be desirable to generate different audio frequency ranges (which may overlap) with different drivers. 
     Reference is next made to  FIGS. 5 and 6 , which illustrate a loudspeaker  120  according to a second embodiment of the present invention. Components of loudspeaker  120  corresponding to components of loudspeaker  20  are identified with similar reference numerals increased by  100 . Loudspeaker  120  has a housing  122 , a driver  124 , a housing baffle  126 , input terminals  128 ,  130 , a sound reflector  132 , which are structured and operate in generally the same manner as the corresponding components of loudspeaker  20  ( FIG. 1 ). In addition, loudspeaker  120  has a second driver  134 , a second sound reflector  136  and a cross-over  152 . 
     Driver  134  is mounted in the top side of sound reflector  132  and has an axis  138 . Sound reflector  136  has a support  137  which extends from support  154  (or from the top of sound reflector  132 ). Sound reflector is positioned generally above driver  134 . 
     Driver  134  is a high frequency driver, which is selected to produce sound waves at a higher frequency range than driver  124 , typically with some overlap between the two frequency ranges. For example, in loudspeaker  120 , driver  124  may be selected to produce sound between 50 Hz and 2 kHz and driver  134  may be selected to produce sound between 1 kHz and 18 kHz. (Typically the high end of the frequency range of driver  124  will be lower than that of driver  24  in loudspeaker  20 , since loudspeaker  20  does not have a high frequency driver.) In another embodiment of the present invention, drivers  124  and  134  may be selected to have any suitable frequency range. 
     Cross-over  152  is mounted inside housing  122  and is coupled to terminals  128 ,  130  by wires  160 ,  162 . Driver  124  coupled to cross-over  152  by wires  160   l ,  162   l . Driver  134  is coupled to cross-over  152  by wires  160   h  and  162   h . Cross-over  152  receives an audio signal from terminals  128 ,  130  and divides it into a low frequency audio signal and a high frequency audio signal in known manner. The low and high frequency audio signals have overlapping frequency ranges. 
     Driver  124  receives the low frequency audio signal from cross-over  152  and in response produces audio waves  172  in the same manner as driver  124  produces audio waves  72  ( FIG. 4 ). Audio waves  172  are reflected by reflector  132  as sound waves  174 . 
     Driver  134  receives the high frequency audio signal from cross-over  152  and in response produces audio waves  173 . Reflector  136  is positioned such that at least some of audio waves  173  are incident on it. A reflecting surface  159  of reflector  136  reflects audio waves  173  outward from loudspeaker  120  as sound waves  175 . A relatively large portion of sound waves  175  is directed from the front of loudspeaker  120 . Progressively less of sounds waves  175  are in each direction at progressively larger angles from the front of loudspeaker  120 . 
     The use of separate drivers  124  and  134  in loudspeaker  120  has several advantages over the single driver design of loudspeaker  20 . First, the use of two drivers  124  and  134  allows drivers to be selected that provide a better sound quality within their selected frequency ranges. Second, the use of independent reflectors  132 ,  136  for the separate frequency ranges allows the sound field for each frequency range to be shaped more precisely, allowing the overall sound field of loudspeaker  120  to be shaped more closely to a desired shaping. The driver  134  is located further from the front of the loudspeaker  120  than the driver  124 . Similarly, the reflector  136  is further from the front of the loudspeaker  120  than the reflector  132 . As a result, the audio waves  172  from the driver  124  and reflector  132  have less distance to traverse to a listener than the audio waves  173  from the driver  134  and reflector  136 . This is desirable as the audio waves  173  from the high frequency audio signal would otherwise reach a listener slightly before the audio waves  172  from the low frequency audio signal. 
     Reference is next made to  FIG. 7 . Sound waves  174  and  175  are illustrated in cross-section propagating from the front and back of loudspeaker  120 . Sound waves  174  and  175  collectively provide a sound field that covers the frequency ranges of both drivers  124  and  134 . A listener situated at point  199   a  will hear the combined full sound field. Like loudspeaker  20 , loudspeaker  120  produces a three-dimensional sound field. A listener situated at points  199   b  and  199   c  which are respectively above and below the height of speaker  120  will also hear the combined full sound field. A skilled person will be capable of selecting the angles of drivers  124  and  134  and their reflectors  132 ,  136  (labeled in  FIGS. 5 and 6 ) to provide the combined sound field at the height required for any particular embodiment of the present invention. 
     Reference is next made to  FIG. 8 . Speakers  20  and  120  are suitable for use in multiple channel sound systems. Modern home theatre systems commonly include five or more speakers. A typical home theatre loudspeaker system  200  may include a front left loudspeaker  202 , a front right loudspeaker  204 , a center loudspeaker  206 , a rear left loudspeaker  208  and rear right loudspeaker  210 . The sound field of each of these speakers in the 2–5 kHz band is symbolically illustrated in  FIG. 9  by curves  212  (front left loudspeaker  202 ),  214  (front right loudspeaker  204 ),  216  (center loudspeaker  206 ),  218  (rear left loudspeaker  208 ) and  220  (rear right loudspeaker  210 ). Each of these curves illustrate the region in which the associated loudspeaker may be effectively heard, in the shown layout. The five curves  212  to  220  overlap to provide a listening area  222 . A listener situated in the listening area  222  will be able to hear all five speakers  202  to  210  and will enjoy a typical “surround sound” audio presentation from all five speakers, under the control of a sound signal source (not shown). 
     As mentioned earlier, low frequency sounds are relatively non-directional. In addition, a substantial amount of power is often required to generate such low frequency sounds. The five loudspeaker system of  FIG. 8  may be combined in known manner with a low frequency loudspeaker or “sub-woofer” in a “5.1” loudspeaker system that provides a sound field with a wide frequency range. For example, the low frequency loudspeaker may have a frequency range of 20 Hz to 80 Hz. The drivers  124  of speakers  202  to  210  may have a frequency range of 60 Hz to 2 kHz and the driver  134  of speakers  202  to  210  may have a frequency range of 1 kHz to 18 kHz. These frequency ranges are only exemplary and a skilled person will be capable of selecting drivers with frequency ranges that suit a particular application of the present invention. 
     Reference is next made to  FIG. 9 , which illustrates a loudspeaker  320  according to a third embodiment of present invention. Loudspeaker  320  has a structure similar to loudspeaker  120  and corresponding components are identified by similar reference numerals increased by  200 . High frequency driver  334  operates in a manner similar to high frequency driver  134 . However, sound reflector  332  has been hollowed out to provide a sealed rear chamber  335  for high frequency driver  334 . High frequency driver  334  has a hole  337  to release air pressure caused by movement of its cone  351 . This volume of air contained within reflector  332  reduces the fundamental resonance of driver  334 , thereby reducing distortion and improving power handling at the bottom of its frequency range and smoothing out its frequency response. 
     Reference is next made to  FIG. 10 , which shows a loudspeaker  420  according to a fourth embodiment of the present invention. The speakers described above all incorporate circular driver (i.e. drivers  24  and  134 ). The present invention may be used with a driver having an elliptical or other shape. Loudspeaker  420  is similar to loudspeaker  20 . Corresponding components of loudspeaker  420  are identified by similar reference numerals increased by  400 . Driver  424  has an elliptical shape and sound reflector  432  has a corresponding elliptical shape. 
     In other embodiments of the present invention, the driver (or drivers) may have any shape. For example, they may be conical, flat or dome shaped. 
     Loudspeakers  120  and  320  have two drivers and two corresponding reflectors. Other loudspeakers according to the present invention may have three or more drivers and corresponding reflectors. The three or more loudspeakers may have different and possibly overlapping frequency ranges. The drivers of such loudspeakers may be selected to provide a wider combined frequency response or a better quality sound reproduction or both. 
     Reference is next made to  FIG. 11 , which illustrates a fifth embodiment of a loudspeaker  520  according to the present invention. Loudspeaker  520  has three drivers  524 ,  534  and  574 . Driver  524  has a corresponding reflector  532  and driver  534  has a corresponding reflector  536 . Drivers  524 ,  534  and reflectors  532 ,  536  operate in the same manner as drivers  124 ,  134  and reflectors  132 ,  136  of loudspeaker  120  ( FIG. 6 ). Loudspeaker  520  has input terminals  528  and  530  which are coupled to a three way cross-over  552 . Cross-over  552  divides an audio signal (not shown) received at terminal  528 ,  530  into low, mid-range and high frequency components. The high frequency components are provided to driver  534  through wires  560   h ,  562   h . The mid-range frequency components are provided to driver  524  through wires  560   m ,  562   m . The low frequency components are provided to driver  574  through wires  560   l ,  562   l.    
     Driver  574  is selected to have a low frequency operational range and along with crossover  552  reproduces audio in response to the low frequency components of the audio signal. Since the low frequency audio output of driver  574  will be essentially omni-directional, driver  574  does not require a sound reflector. 
     Loudspeaker  520  is capable of producing sounds with a very wide frequency range, depending on the selection of drivers  524 ,  534  and  574 , and with wide listening area. 
     Other variations and modifications of the invention are possible. For example, while the foregoing has referred to drives having cones, those of skill in the art will appreciate that diaphragms of other shapes may be substituted. All such modifications or variations are believed to be within the sphere and scope of he invention as defined by the claims appended hereto.