Abstract:
The present invention comprises a tile-mounted ceiling speaker that combines the ease of installation of a lay-in speaker system with the visual appearance of a tile-mounted speaker system. In one or more embodiments, the apparatus of the present invention includes a support frame and back box assembly configured for installation on top of a ceiling tile and a loudspeaker cartridge configured to be mounted to the support frame through an appropriately-sized hole in the ceiling tile. In one or more embodiments, the invention comprises a peripheral flange and a plurality of flip dogs for mounting the cartridge to the support frame that are configured to be disposed in the interior of the back box when engaged.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This patent application is a continuation of U.S. patent application Ser. No. 13/159,801 filed Jun. 14, 2011, which is a continuation in part of U.S. patent application Ser. No. 12/795,218 filed Jun. 7, 2010 which issued as U.S. Pat. No. 8,109,360 on Feb. 7, 2012, which is a continuation in part of U.S. patent application Ser. No. 12/355,730 filed Jan. 16, 2009 which issued as U.S. Pat. No. 7,866,438 on Jan. 11, 2011, which is a continuation-in-part of U.S. patent application Ser. No. 12/163,929 filed Jun. 27, 2008 which issued as U.S. Pat. No. 7,861,825 on Jan. 4, 2011, all of which are incorporated by reference in their entirety herein. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    (1) Field of the Invention 
         [0003]    The present invention relates to a loudspeaker system for mounting in a suspended ceiling comprising a support frame and back box assembly and a removable speaker cartridge. 
         [0004]    (2) Background of the Invention 
         [0005]    Suspended ceilings, consisting of ceiling tiles supported by a grid of t-bar frames, are common in business as well as in some residential environments. It is often desired to mount loudspeakers in suspended ceilings to provide for communications and/or entertainment. Consequently, various types of loudspeaker systems have been developed for installation in suspended ceilings. 
         [0006]    One type of prior art ceiling loudspeaker system consists of a loudspeaker mounted to a conventional ceiling tile. A hole is cut in the ceiling tile to accommodate the speaker, and the speaker is mounted to the tile over, in, or adjacent to the hole. The size of speaker that can be used in this type of loudspeaker system is limited because conventional ceiling tiles have limited structural strength and in some cases are rated by the manufacturers as having no structural strength at all.  FIG. 1  shows a modification of this type of ceiling loudspeaker system that adds a support frame that provides additional support for the loudspeaker. As shown in  FIG. 1 , the support frame includes support bars  105  and  110  that extend across the back of a ceiling tile  115  to t-bar frames (such as t-bar frame  120 ) that support the ceiling tile, and a support ring  125  that is mounted to support bars  105  and  110  adjacent to the hole  130  in ceiling tile  115 . The speaker is mounted on support ring  125  so that some or all of the weight of the speaker is supported by the support bars and ring and not just the speaker tile, allowing a heavier speaker to be used. The speaker can be a single speaker or can be a speaker assembly that includes multiple speakers. A further modification of this type of ceiling loudspeaker system adds a metal “can” to the back of the speaker assembly that is intended to comply with fire codes for plenum installations. 
         [0007]    An example of a ceiling speaker assembly that includes a back can and that is intended to be mounted in a ceiling tile using a support frame like that shown in  FIG. 1  is the S126CT model ceiling speaker sold by Extron Electronics, which is shown in  FIG. 2 . As shown in  FIG. 2 , the S126CT ceiling speaker assembly  200  includes a woofer  205  with a coaxially mounted tweeter  210  mounted to a speaker frame  215 . A metal back can  220  is mounted to the back of speaker frame  215  forming a chamber that encloses the back side of woofer  205 . A removable panel in the back of metal back can  220  (not shown) provides access for electrical connections to the speaker unit. A crossover circuit may also be mounted to the rear of woofer  205 . Internal speaker wires lead from the crossover circuit to each of woofer  205  and tweeter  210 . To improve the acoustic response, a port  225  is formed in speaker frame  215 . A plurality of mounting doglegs (sometimes referred to herein as “dogs” or “flip dogs”)  230  are attached to the rear of speaker frame  215 . To mount speaker assembly  200  onto a ceiling tile, an appropriate hole is cut into the ceiling tile. A support frame such as that shown in  FIG. 1  is installed on top of the ceiling tile. The rear of speaker assembly  200  is inserted into the hole in the ceiling tile from the bottom until speaker frame  215  is flush against the bottom surface of the ceiling panel. Mounting dogs  230  are then pivoted such that the ends of their doglegs are disposed over the support ring on the back side of the ceiling tile, thereby securing speaker assembly  200  to the ceiling tile and support frame. 
         [0008]    Another type of ceiling speaker is a “lay-in” ceiling speaker, an embodiment of which is disclosed, for example, in U.S. Pat. No. 6,944,312 issued to Mason et al. entitled “Lay-In Ceiling Speaker.” The lay-in speaker disclosed in Mason et al. is intended to replace an entire ceiling tile. It consists of a speaker mounted to a perforated metal grille, which is crimped to a fiberglass back box, forming a generally rigid loudspeaker assembly that has the same lateral dimensions as a standard ceiling tile and that can be mounted in a suspended ceiling simply by removing an existing ceiling tile and putting the “lay-in” loudspeaker assembly in its place, the edges of the “lay-in” speaker resting on the t-bar support frames of a suspended ceiling in the same manner as a ceiling tile. When installed, the visual appearance of a lay-in speaker is that of a perforated grill having the size and shape of a ceiling tile. 
         [0009]    Although lay-in speakers are easy to install, sometimes the visual appearance of a tile-mounted ceiling speaker is preferred over the appearance of a lay-in speaker. Until now, there has been no ceiling speaker assembly that combines the ease of installation of a lay-in speaker with the aesthetics of a tile-mounted ceiling speaker. 
       BRIEF SUMMARY OF THE INVENTION 
       [0010]    The present invention comprises a method and apparatus for installing a tile-mounted ceiling speaker that combines the ease of installation of a lay-in speaker system with the visual appearance of a tile-mounted speaker system. In one or more embodiments, the apparatus of the present invention includes a support frame and back box assembly configured for installation on top of a ceiling tile and a loudspeaker cartridge configured to be mounted to the support frame through an appropriately-sized hole in the ceiling tile. In one or more embodiments, the method of the present invention comprises forming an appropriately-sized hole in a ceiling tile, laying an integrated back box and support frame on top of the ceiling tile, connecting wires from an external audio source to terminals provided at the back box, connecting wires provided on the inside of the back box to a loudspeaker cartridge, inserting the loudspeaker cartridge into the hole in the ceiling tile from below, fastening the loudspeaker cartridge to the support frame, and fastening a grille to the loudspeaker cartridge. In one or more embodiments, a variety of interchangeable loudspeaker cartridges having differing loudspeaker configurations are provided. In one or more embodiments, the support frame and back box assembly is configured to allow installation of more than one loudspeaker cartridge. In one or more embodiments, the loudspeaker cartridges are configured for use both with a back box and without back box. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]    The present invention may be understood and its features made apparent to those skilled in the art by referencing the accompanying drawings. 
           [0012]      FIG. 1  is a perspective view of an embodiment of a support frame of the prior art. 
           [0013]      FIG. 2  is a perspective view of ceiling speaker assembly of the prior art. 
           [0014]      FIG. 3  is an exploded perspective view of an embodiment of a support frame and back box assembly of the present invention. 
           [0015]      FIG. 4  is a rear perspective view of an embodiment of a support frame and back box assembly of the present invention. 
           [0016]      FIG. 5  is a front perspective view of an embodiment of a support frame and back box assembly of the present invention. 
           [0017]      FIG. 6  is an exploded perspective view of an embodiment of a speaker cartridge of the present invention. 
           [0018]      FIG. 7  is a rear perspective view of an embodiment of a speaker cartridge of the present invention. 
           [0019]      FIG. 8  is a front view of an embodiment of a speaker cartridge of the present invention. 
           [0020]      FIG. 9  is a close up view showing electrical connections for an embodiment of a back box of the present invention. 
           [0021]      FIG. 10  is a close up view showing electrical connections for an embodiment of a speaker cartridge of the present invention. 
           [0022]      FIGS. 11A-11C  show a method of mounting an embodiment of a support frame and back box assembly of the present invention. 
           [0023]      FIGS. 12A-12C  show a method of mounting an embodiment of a speaker cartridge of the present invention. 
           [0024]      FIG. 13A  is a perspective view of an embodiment of a speaker cartridge of the present invention mounted in a ceiling tile. 
           [0025]      FIG. 13B  is a cutaway perspective view of an embodiment of a speaker cartridge of the present invention mounted to an embodiment of a support frame and back box assembly of the present invention. 
           [0026]      FIGS. 14A-14C  show removable spacer tabs of one or more embodiments of the present invention. 
           [0027]      FIG. 15  is an exploded view of a “flip dog” assembly of one or more embodiments of the present invention. 
           [0028]      FIGS. 16A-16B  show assembled “flip dog” assemblies of one or more embodiments of the present invention. 
           [0029]      FIGS. 17A-17C  illustrate a process for engaging a “flip dog” according to one or more embodiments of the present invention. 
           [0030]      FIGS. 18A-18B  show details of a screw hole of a “flip dog” of one or more embodiments of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0031]    In the following description, numerous specific details are set forth to provide a more thorough description of the present invention. It will be apparent, however, to one skilled in the art, that the present invention may be practiced without these specific details. In other instances, well-known features have not been described in detail so as not to obscure the invention. 
         [0032]      FIG. 3  is an exploded view showing components of a support frame and back box assembly  375  of an embodiment of the present invention. In the embodiment of  FIG. 3 , components of support frame and back box assembly  375  include a support frame  300 , a back box  305 , and an outer shield  310 . 
         [0033]    In the embodiment of  FIG. 3 , support frame  300  comprises a metal, plastic, or other material or materials formable into the desired shape and form. In one or more embodiments, support frame  300  is formed as a sheet metal stamping. In the embodiment of  FIG. 3 , support frame  300  includes a planar portion  301 , an opening  304 , a plurality of stiffening ribs  303 , and a lip  302 . In one or more embodiments, lip  302  is initially formed at an approximately right angle to planar portion  301 . In one or more embodiments, support frame  300  is formed from a sheet of material. In alternative embodiments, stiffening ribs  303  and/or lip  302  may not be integrally formed with planar portion  301 , but may comprise separately formed components that are affixed to planar portion  301  to form support frame  300 . In the embodiment of  FIG. 3 , support frame  300  comprises a single centrally-located round opening  304  for receiving a speaker or a speaker cartridge. In one or more other embodiments, support frame  300  may comprise two or more openings for receiving speakers or speaker cartridges. The openings may have the same or different shapes (round, rectangular or other) and sizes, and may each be located anywhere in speaker frame  300 . Further, planar portion of speaker frame  300  need not be formed from a single piece of material, but may be assembled from separately formed pieces. Further, although speaker frame  300  is shown as having a generally rectangular shape, any other desired shape can be used. 
         [0034]    In the embodiment of  FIG. 3 , back box  305  comprises a raised portion  309  and an edge portion  308 . In one or more embodiments, edge portion  308  comprises a plurality of spacer tabs  307  that allow the overall length of back box  305  to be adjusted so that support frame and back box assembly  375  can be used with a plurality of ceiling t-bar spacings. In one or more embodiments, the overall length of support frame and back box assembly  375  with spacer tabs  307  intact is approximately 2 feet, which is a standard width for ceiling tiles in the United States. In one or more embodiments, with spacer tabs  307  removed (for example by breaking off with a tool such as a pair of pliers), the overall length of support frame and back box assembly  375  is approximately 600 mm, which is a standard width for ceiling tiles in some European countries.  FIGS. 14A-14C  illustrate how spacer tabs  307  may be removed (for example with pliers  1401  as shown in  FIG. 14B ) to create two different overall lengths for support frame and back box assembly  375 . Although spacer tabs  307  are shown as all having the same length and disposed along only one side of support frame and back box assembly  375 , in one or more alternative embodiments, spacer tabs may be included on other sides. Further, two or more sets of spacer tabs having different lengths may be used along one or more sides, providing additional discrete, selectable variations of overall lengths and/or widths for support frame and back box assembly  375  depending on which tabs are removed. In one or more embodiments, spacer tabs are scored or notched to facilitate removal of the tabs. 
         [0035]    In one or more embodiments, back box  305  is formed from high molecular weight polyethylene (“HMWPE”), though back box  305  can be formed from any other plastic, metal, or composite material or materials. In one or more embodiments, back box  305  comprises a recessed portion  314  that is configured to accommodate a stiffening plate  320  to provide additional structural rigidity. In one or more embodiments, stiffening plate  320  is made from a relatively stiff material, such as medium density fiberboard (“MDF”). The use of stiffening plate  320  allows support frame and back box assembly  375  to have significant rigidity (which is desirable for improved acoustical response) yet be relatively light in weight. In one or more embodiments, back box  305  comprises a recessed electrical compartment  311  that includes electrical terminals  340  for making external electrical connections. 
         [0036]    In the embodiment of  FIG. 3 , outer shield  310  is configured to be mountable over back box  305  such that the inside surface of outer shield  310  conforms generally to the outside surface of back box  305 . In one or more embodiments, outer shield  310  includes a raised portion  360  and an edge portion  365 . In one or more embodiments, outer shield  310  is formed from materials as is known in the art that provide fire and heat resistance in conformity with applicable building codes. In one or more embodiments, outer shield  310  comprises a composite construction comprising an inner mineral fiber or fiberglass shell and an outer metal foil layer. In one or more embodiments, outer shield  310  conforms to the Underwriters&#39; Laboratories UL2043 rating. In one or more embodiments, outer shield  310  includes an opening  334  that is configured to provide access to electrical compartment  311  of back box  305  when outer shield  310  is assembled to back box  305  and support frame  300 . In one or more embodiments, outer shield  310  is provided with a pair of plates  335  comprising threaded holes that can be used to mount a cover plate  350  over opening  334  using fasteners  355 . 
         [0037]    In the embodiment of  FIG. 3 , support frame  300 , back box  305 , stiffening plate  320  and outer shield  310  are assembled together to form an embodiment of a support frame and back box assembly of the invention. In one or more embodiments, stiffening plate  320  is fastened to back box  309  using a plurality of screws  330 . Back box  305  is fastened to support frame  300  and stiffening plate  345  using bolts  325 , spacers  315  and barrel nuts  345 . In one or more embodiments, when assembled, the components work together to form an assembly that has a rigidity greater than the rigidity of the individual components. 
         [0038]    In one or more embodiments, lip  302  of support frame  300  includes openings  313  through which spacer tabs  307  of back box  305  protrude when back box  305  is mounted to support frame  300 . 
         [0039]    In the embodiment of  FIG. 3 , after back box  305  is assembled to support frame  300 , outer shield  310  is placed over back box  305  such that edge portion  365  of outer shield  310  rests on edge portion  308  of back box  305 . In one or more embodiments, lip  302  of support frame  300  is thereafter folded over edge portion  365  of outer shield  310  such that lip  302  holds outer shield  310  in place, as shown in  FIG. 4 , which shows a top view of an embodiment of a resulting support frame and back box assembly  375  of the invention. A bottom view of support frame and back box assembly  375  is shown in  FIG. 5 . In one or more embodiments, additional or other fastening methods and/or fasteners may be used to fasten support frame  300  and/or back box  305  to outer shield  310  as will be known to those of skill in the art. For example, in one or more embodiments, spring-loaded or folded clips may be used to hold outer shield  310  to support frame  300  and back box  305 . 
         [0040]    An embodiment of a speaker cartridge  600  of the invention which may be used independently of or with a support frame and back box assembly such as support frame and back box assembly  375  is shown in  FIGS. 6 ,  7  and  8 .  FIG. 6  is an exploded view showing components of an embodiment of speaker cartridge  600 .  FIGS. 7 and 8  are top and bottom views, respectively, of embodiments of an assembled speaker cartridge  600 . 
         [0041]    In the embodiment of  FIG. 6 , speaker cartridge  600  comprises a cartridge frame  601  to which various components are mounted. In one or more embodiments, cartridge frame  601  is molded from a plastic, cast from a metal, or formed in any other manner as will be known by those of skill in the art. In one or more embodiments, cartridge frame  601  is molded from HMWPE. In one or more embodiments, cartridge frame  601  is formed to fit into opening  304  of support frame  300 . In one or more embodiments, cartridge frame  601  includes a flange  602 . In one or more embodiments, cartridge frame  601  provides mounting locations for components that are intended to be mounted to cartridge frame  601 . In the embodiment of  FIG. 6 , components mounted to cartridge frame  601  include a speaker  610 , a tweeter  615 , a tweeter bracket  605 , a transformer  624 , a switch  614 , a crossover circuit board  624 , and a plurality of “flip dog” attachment clips each comprising a flip dog base  618  (which may, for example, be integrally formed with cartridge frame  601 ), rotatable flip dog  620  and a flip top cap  622 . In one or more embodiments, speaker  610  is a midrange speaker or a woofer. In one or more embodiments, transformer  624  is configured to match an incoming audio signal to the signal requirements of speaker  610 . In one or more embodiments, transformer  624  has multiple taps that can be selected by switch  614  so that speaker cartridge  600  can be used with a variety of input signal configurations. 
         [0042]    In the embodiment of  FIG. 6 , crossover circuit board  624  includes a conventional crossover circuit that divides the incoming audio into primarily lower frequency signals that are sent to speaker  610  and primarily higher frequency signals that are sent to tweeter  615 , as is known in the art. 
         [0043]      FIG. 7  shows how components are assembled to cartridge frame  601  in one or more embodiments of the invention. In the embodiment shown in  FIG. 7 , a portion of cartridge frame  601  that is configured to fit within opening  304  of support frame  300  has an inner perimeter  712  that has a diameter equal to or less than the diameter of opening  304 . Flange  602  extends outwards from perimeter  712  to an outer perimeter  710  that has a diameter greater than the diameter of opening  304  of support frame  300 . In the embodiment of  FIG. 6 , flip dogs  620  are rotatably mounted to flip dog bases  618  such that legs  706  of flip dogs  620  can be rotated from an inward position in which they do not extend beyond inner perimeter  712  and can therefore be inserted into opening  304  of support frame  300  to an outward position in which they extend beyond inner perimeter  712  so as to extend over the perimeter of opening  304  so as to hold speaker cartridge  600  in place adjacent to support frame  300  when speaker cartridge  600  is assembled to support frame and back box assembly  375 . In one or more embodiments, flip dogs  620  and flip dog bases  618  are configured such that the rotational position of flip dogs  620  can be manipulated from the bottom side of cartridge frame  601 , for example by use of a tool such as a screwdriver. In one or more embodiments, switch  614  is also configured so as to allow operation of switch  614  from the bottom of cartridge frame  601 . 
         [0044]    In the embodiment of  FIG. 7 , cartridge frame  601  includes a port  703 , a removable port cover  612 , and a port cover storage location  702 . When mounted to a support frame and back box assembly such as support frame and back box assembly  375 , port cover  612  may be removed and stored in port cover storage location  702  so that port  703  functions like a conventional speaker port, providing a path between the outside and inside of the speaker enclosure formed by the combination of speaker cartridge  600  and support frame and back box assembly  375 . In one or more embodiments, leaving port  703  covered provides better audio response if speaker cartridge  600  is mounted in a ceiling tile or otherwise used in a manner in which the rear of speaker cartridge  600  is not enclosed by a back box or other housing. 
         [0045]      FIG. 8  shows a bottom view of one or more embodiments of speaker cartridge  600 . In the embodiment of  FIG. 8 , tweeter bracket  605  has been mounted to cartridge frame  601 , for example by engaging tabs at the ends of the legs of tweeter bracket  605  with mating slots in cartridge frame  601 . In one or more embodiments, tweeter bracket  605  allows different tweeters to be used with speaker cartridge  600 . In one or more embodiments, different tweeter brackets  605  may be interchangeably used with speaker cartridge  600 . In one or more embodiments, tweeter brackets  605  may be configured to provide various assembled locations for tweeter  615  with respect to speaker  610 , allowing the assembled location of a particular tweeter  615  to be configured to provide a desired acoustical interaction with speaker  610 . In the embodiment of  FIG. 8 , cartridge frame  601  includes orifices  802  that provide access to flip dogs  620  with an appropriate tool, such as, for example, a screwdriver, that can be used to rotate flip dogs  620  from a retracted position (in which the legs  706  do not interfere with insertion of speaker cartridge  600  into opening  304  of support frame  300 ) to an extended position (in which legs  706  extend beyond opening  304  of support frame  300 ). In one or more embodiments, cartridge frame  601  also includes an opening  805  that provides access to switch  614 . 
         [0046]      FIGS. 15 to 18  show details of a flip dog assembly  1500  of one or more embodiments of the invention. In the embodiment shown in  FIG. 15 , components of flip dog assembly  1500  include bottom screw  1510 , flip dog base  618  (which may be integrally formed with cartridge frame  601 ), spring  1501 , flip dog  620  (which includes leg  706 ), flip dog cap  622 , and cap screws  1505 . Flip dog base  618  includes a bore  1511  and an inclined surface  1512  that together with inclined surface  1513  of flip dog cap  622  forms a guide passage for leg  706  of flip dog  620  as discussed in greater detail with respect to  FIGS. 16A and 16B  below. 
         [0047]    In one or more embodiments, flip dog assembly  1500  may be assembled by inserting spring  1501  and flip dog  620  in bore  1511  of flip dog base  618 , placing flip dog cap  622  over flip dog  620  such that the top  1522  of flip dog  620  engages bore  1515  of flip dog cap  622 , and fastening flip dog cap  622  to flip dog base  618  using cap screws  1505 . Bottom screw  1510  can then be inserted through the bottom of flip dog base  618  through spring  1501  (which is now partially compressed) and partially screwed into the bottom of flip dog  620 , as described in greater detail below. The resulting flip dog assembly  1500  is shown in  FIGS. 16A and 16B   
         [0048]    As shown in  FIGS. 16A and 16B , in one or more embodiments, flip dog cap  622  includes a notch  1517  that maintains leg  706  in its retracted position while speaker cartridge  600  is being inserted into a mounting hole (e.g. in a ceiling tile or in a support frame, such as support frame  300  of support frame and back box assembly  375 ). Leg  706  is pressed upwards into notch  1517  by the upwards bias of spring  1501 . 
         [0049]      FIGS. 17A-17C  show how leg  706  is moved from its retracted position as shown in  FIGS. 16A and 16B  to its engaged position as shown in  FIG. 17C . The movement is accomplished by screwing bottom screw  1510  into the bottom of flip dog  620  such that flip dog  620  is pulled downwards into flip dog base  618  though guide passage  1610  formed by flip dog cap  622  and flip dog base  618 . As shown in  FIGS. 17A-17C , as flip dog  620  is pulled downwards by bottom screw  1510 , the configuration of passage  1610  causes leg  706  first to disengage from notch  1517  and then to rotate outwards into its extended position as shown in  FIG. 17B . Further tightening of bottom screw  1510  draws leg  706  further downwards into its fully engaged position, as shown in  FIG. 17C . 
         [0050]      FIGS. 18A and 18B  show a configuration of a screw bore  1801  in flip dog  620  in one or more embodiments of the invention. As shown in  FIG. 18A , screw bore  1801  includes a guide portion  1810  that has a diameter approximately the same diameter as the outside diameter of the threads of screw  1510  and a screw engagement portion  1805  that has a diameter that is less than the outside diameter of the threads of screw  1510 . Guide portion  1810  aligns bottom screw  1510  with screw engagement portion  1805  as screw  1510  is inserted into screw bore  1810 , preventing screw  1510  from becoming misaligned as screw  1510  is screwed into engagement portion  1805 . 
         [0051]    Although cartridge frame  601  is shown in the embodiment of  FIG. 8  to have a generally round shape that generally matches the shape of opening  304  in support frame  300 , in one or more embodiments, other shapes for both cartridge frame  601  and opening  304  can be used. Further, although cartridge frame  601  of  FIG. 8  is configured for a single woofer or midrange speaker and a single tweeter, in one or more other embodiments, cartridge frame  601  can be configured for multiple midrange speakers/woofers and/or multiple tweeters. 
         [0052]      FIG. 9  shows how external wiring is connected to electrical terminals  340  of support frame and back box assembly  375  in one or more embodiments of the invention. In the embodiment shown in  FIG. 9 , a pair of external electrical leads  915  are fed through a conduit header  905  mounted to cover plate  350  (which has been removed to allow access) and attached to Euro-type screw electrical terminals  340  in a recessed electrical compartment  311  formed in back box  305  and accessible through opening  334  of outer shield  310 . A pair of internal electrical leads  920  lead from screw electrical terminals  340  into the interior of back box  305 . 
         [0053]      FIG. 10  shows how internal leads  920  are connected to crossover circuit board  624  in one or more embodiments of the invention. In the embodiment of  FIG. 10 , internal leads  920  (which may, for example, be connected to external leads  915  via electrical terminals  340 ) are connected to an electrical connector  1010  (for example a Molex connector) that is configured to removably mate with a mating electrical connector  624  (for example a Molex connector) connected to crossover circuit board  624 . Using removable mating connectors for connecting internal leads  920  to crossover circuit board  624  facilitates installing speaker cartridge  600  and support frame and back box assembly  375  into a suspended ceiling, as described below. 
         [0054]      FIGS. 11A-11C  illustrate steps for installing a support frame and back box assembly  375  into a suspended ceiling according to one or more embodiments of the invention.  FIG. 11A  shows a support frame and back box assembly  375  placed into a desired position in a grid of t-bar ceiling tile support bars  1105 .  FIG. 11B  shows a ceiling tile  1110  placed into the same position in grid  1105  in which support frame and back box assembly  375  is shown in  FIG. 11A . In  FIG. 11B , an opening  1120  has been cut in ceiling tile  1110  that corresponds to the location of opening  340  of support frame  300  of support frame and back box assembly  375  of  FIG. 11A .  FIG. 11C  shows support frame and back box assembly  375  placed in position on top of ceiling tile  1110 . 
         [0055]      FIGS. 12A-12C  illustrate steps for installing a speaker cartridge  600  into an opening  1120  of a ceiling tile  1110  with or without a support frame and back box assembly  375  according to one or more embodiments of the invention.  FIG. 12A  is a bottom view of a ceiling tile  1110  with an opening  1120 . A support frame and back box assembly  375  may or may not have been placed on top of ceiling tile  1110 . If a support frame and back box assembly  375  has been placed on top of ceiling tile  1110 , opening  304  of support frame  300  will be in the same location as opening  1120  of ceiling tile  1110 . 
         [0056]      FIG. 12B  shows how electrical leads  1015  are fed through opening  1120  of ceiling tile  1110  and attached to speaker cartridge  600 , for example by using connectors such as connectors  1005  and  1010  of the embodiment of  FIG. 10 . If a support frame and back box assembly  375  has been placed on top of ceiling tile  1110 , electrical leads  1015  may for example be internal electrical leads  920  of the embodiment of  FIG. 9 . 
         [0057]      FIG. 12C  shows how a screwdriver  1210  may be used to secure speaker cartridge  600  to ceiling tile  1110  (if no support frame and back box assembly  375  is present) or to ceiling tile  1110  and support frame  300  of support frame and back box assembly  375  (if a support frame and back box assembly  375  is present) by tightening bottom screw  1510 , thereby moving flip dogs  620  from their retracted to engaged positions via access passages provided on the bottom side of speaker cartridge  600  such as, for example, orifices  802  of the embodiment of  FIG. 8 . After speaker cartridge  600  has been secured to ceiling tile  1110  and/or support frame and back box assembly  375 , a detachable decorative grille  1310  may be attached to the bottom of speaker cartridge  600 , as shown, for example, in  FIG. 13A . In  FIG. 13B , ceiling tile  1110  is rendered invisible to show the assembly of speaker cartridge  600  to support frame and back box assembly  375  in one or more embodiments of the invention. 
         [0058]    Thus one or more embodiments of a ceiling speaker system comprising a support frame and back box assembly and a mating speaker cartridge has been disclosed. An advantage of the disclosed invention is that it allows a division of labor in installing a ceiling speaker system that corresponds to a common division of labor in building trades. An example of such a division of labor is between a building contractor that installs a suspended ceiling, an electrician that installs building wires, and an audio/video system installer that installs speakers. Using one or more embodiments of the invention, a building contractor can place a support frame and back box assembly on top of a ceiling tile and cut an appropriate opening in the ceiling tile. The contractor typically would also install safety support wires (which may be required by applicable building and/or safety codes for seismic or other reasons) from the support frame and back box assembly to a support structure, such as a ceiling joist. An electrician can run external wiring to the electrical terminals of the back box of the support frame and back box assembly. After the support frame and back box assembly is in place in the ceiling and the external electrical wires have been attached, an audio/video system installer can attach the internal leads of the support frame and back box assembly to a speaker cartridge, and install the speaker cartridge into the ceiling tile and support frame and back box assembly from below. 
         [0059]    A further advantage of the invention is that the support frame and back box assembly of the one or more embodiments of the invention forms a loudspeaker enclosure that has a relatively large volume but a low profile that allows installation in ceilings that have limited vertical clearance above the ceiling tiles. A further advantage is that in one or more embodiments, the fire-resistant back box encloses the entire rear of the speaker cartridge assembly, including its mounting hardware, which remain exposed in prior art ceiling speaker systems (such as, for instance, flip dogs  230  of the prior art ceiling speaker shown in  FIG. 2  that are not enclosed by back can  230  and that could therefore be subjected directly to fire). 
         [0060]    Although the present invention has been described with respect to certain specific embodiments, it will be clear to those skilled in the art that the inventive features of the present invention are applicable to other embodiments as well, all of which are intended to fall within the scope of the present invention. For example, although certain fastening methods and fasteners (e.g. screws) are disclosed for assembling various components of the invention, any other fastening methods and/or fasteners may be used (such as, for example, adhesives). Further, certain features of the invention can be used with other items other than a ceiling speaker. For example, the removable spacing tabs of the invention may be used with other items for which it would be useful to vary an overall dimension by discrete amounts, including items to be mounted in suspended ceilings, and elsewhere. Similarly, the flip dog assembly of the present invention can be used with other items that are intended to be mounted in holes in ceilings, walls, desktops, and elsewhere. Other variations of and uses for various aspects of the present invention will be apparent to those of skill in the art.