Abstract:
A new audio transducer for mobile devices having a collar with side openings that provide side venting to a back volume within an enclosure. The side openings eliminate the need for a typical frame and back vents thereon, which leads to a smaller size speaker. Each of the side openings have a maximum size less than the size of an adsorber material, which prevents the adsorber material coming into contact with the magnets, coil, and membrane of the speaker. The side openings and the size thereof also permit the enclosure to be directly filled with an adsorber material. The direct filling of the adsorber leads to more even and complete distribution of the adsorber within the back volume, which, in turn, improves sound quality of the speaker.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    a. Field of the Invention 
         [0002]    The invention relates to an audio transducer, such as a speaker to transduce an electrical audio signal into acoustic sound or a receiver to transduce an acoustic sound into an electrical audio signal. This invention furthermore relates to a micro speaker optimized for high acoustic output and located within a small volume of a mobile device, such as a mobile phone, a tablet, a gaming device, a notebook or similar device. 
         [0003]    b. Background Art 
         [0004]    Prior art micro speakers are housed within an enclosure that provides a back volume for the speaker. Often the back volume is filled with an adsorber material which leads to an apparent virtual enlargement of the back volume. The adsorber serves to lower the resonant frequency of the speaker to a value that can only be achieved with a larger back volume in the absence of an adsorber. In prior art speakers, the enclosure may be filled with an adsorber through a small hole which leads to uneven or incomplete filling of the enclosure with the adsorber, which results in a decreased sound quality. 
       SUMMARY OF THE INVENTION 
       [0005]    It is an object of the invention to have an audio transducer for mobile devices without the disadvantages of known transducers. A new audio transducer for mobile devices, in particular for a micro speaker, comprises a collar with side openings that provide side venting to a back volume within an enclosure. The side openings eliminate the need for a typical frame and back vents thereon, which leads to a smaller size speaker. Furthermore, each of the side openings have a maximum size less than the size of an adsorber material, which prevents the adsorber material coming into contact with the magnets, coil, and membrane of the speaker. The side openings and the size thereof also permit the enclosure to be directly filled with an adsorber material. The direct filling of the adsorber leads to more even and complete distribution of the adsorber within the back volume, which, in turn, improves sound quality of the speaker. Further details and advantages of such an audio transducer will become apparent in the following description and the accompanying drawings. 
         [0006]    Briefly therefore, one aspect of the invention is directed to an audio transducer, comprising a membrane assembly, a coil assembly, and a magnet system. The membrane assembly includes a membrane having a perimeter, a membrane ring affixed to the perimeter of the membrane, and a membrane plate affixed to the membrane. The magnet system comprises a pot assembly, a perimeter magnet assembly, and an air gap formed therebetween. The pot assembly has a pot plate having a perimeter, a center magnet affixed to the pot plate, and a top plate affixed to the center magnet opposite the pot plate. The perimeter magnet assembly has a population of outer magnets arranged proximate the perimeter of the pot plate and surrounding the center magnet, and a ring plate affixed to the population of outer magnets. The audio transducer also includes a substantially rectangular collar having a first portion substantially parallel to the pot plate, a substantially rectangular hole extending through the first portion of the collar, and a second portion extending substantially perpendicular downward from the first portion. A population of openings extend through the second portion to provide side venting to a back volume. The population of openings permit direct filling of an enclosure with an adsorber. Additionally, a support tab extends substantially perpendicular outward from the second portion of the collar. The coil assembly includes a coil located in the air gap and a pair of electrical leads extending from the coil. The top side of the coil is affixed to the membrane. 
         [0007]    While embodiments of the audio transducer are shown and described as having a rectangular shape, it will be understood that in other embodiments, the audio transducer may have a variety of shapes, including, but not limited to, circular and ovular. Accordingly, the invention is not limited to audio transducers having a rectangular shape. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]    These and other aspects, features, details, utilities, and advantages of the invention will become more fully apparent from the following detailed description, appended claims, and accompanying drawings, wherein the drawings illustrate features in accordance with exemplary embodiments of the invention, and wherein: 
           [0009]      FIG. 1  shows an exploded top perspective view of the relevant parts of a prior art rectangular micro speaker; 
           [0010]      FIG. 2A  shows a bottom perspective view of the relevant parts of a prior art rectangular micro speaker; 
           [0011]      FIG. 2B  shows a bottom perspective view of the relevant parts of a prior art rectangular micro speaker; 
           [0012]      FIG. 3A  shows a top perspective view of a prior art rectangular micro speaker in a portion of a prior art enclosure; 
           [0013]      FIG. 3B  shows a side perspective section view of a prior art rectangular micro speaker in a prior art enclosure; 
           [0014]      FIG. 3C  shows a side perspective section view of a prior art rectangular micro speaker in a prior art enclosure; 
           [0015]      FIG. 4  shows an exploded top perspective view of a rectangular micro speaker according to a first embodiment of the invention; 
           [0016]      FIG. 5  shows a top perspective view of a coil assembly of a rectangular micro speaker according to the first embodiment of the invention; 
           [0017]      FIG. 6A  shows a top perspective view of a rectangular micro speaker according to the first embodiment of the invention; 
           [0018]      FIG. 6B  shows a bottom perspective view of a rectangular micro speaker according to the first embodiment of the invention; 
           [0019]      FIG. 7  shows a side perspective section view of a rectangular micro speaker according to the first embodiment of the invention; 
           [0020]      FIG. 8  shows a top perspective partial cutaway view of a rectangular micro speaker according to the first embodiment of the invention; 
           [0021]      FIG. 9A  shows a top perspective view of a rectangular micro speaker assembled into a first portion of an enclosure according to the first embodiment of the invention; 
           [0022]      FIG. 9B  shows a top perspective view of a rectangular micro speaker assembled into an enclosure according to the first embodiment of the invention; 
           [0023]      FIG. 10  shows a side perspective section view of a rectangular micro speaker assembled into an enclosure according to the first embodiment of the invention; 
           [0024]      FIG. 11  is a flowchart describing a method of assembling the rectangular micro speaker into an enclosure according to the first embodiment of the invention; 
           [0025]      FIG. 12A  is a bottom perspective view of a collar of a rectangular micro speaker according to a second embodiment of the invention; and 
           [0026]      FIG. 12B  is a top perspective view of a collar of a rectangular micro speaker according to the second embodiment of the invention. 
       
    
    
       [0027]    Like reference numbers refer to like or equivalent parts in the several views. 
       DETAILED DESCRIPTION OF EMBODIMENTS 
       [0028]    Various embodiments are described herein to various apparatuses. Numerous specific details are set forth to provide a thorough understanding of the overall structure, function, manufacture, and use of the embodiments as described in the specification and illustrated in the accompanying drawings. It will be understood by those skilled in the art, however, that the embodiments may be practiced without such specific details. In other instances, well-known operations, components, and elements have not been described in detail so as not to obscure the embodiments described in the specification. Those of ordinary skill in the art will understand that the embodiments described and illustrated herein are non-limiting examples, and thus it can be appreciated that the specific structural and functional details disclosed herein may be representative and do not necessarily limit the scope of the embodiments, the scope of which is defined solely by the appended claims. 
         [0029]    Reference throughout the specification to “various embodiments,” “some embodiments,” “one embodiment,” or “an embodiment,” or the like, means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment. Thus, appearances of the phrases “in various embodiments,” “in some embodiments,” “in one embodiment,” or “in an embodiment,” or the like, in places throughout the specification are not necessarily all referring to the same embodiment. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more embodiments. Thus, the particular features, structures, or characteristics illustrated or described in connection with one embodiment may be combined, in whole or in part, with the features, structures, or characteristics of one or more other embodiments without limitation given that such combination is not illogical or non-functional. 
         [0030]    It must be noted that, as used in this specification and the appended claims, the singular forms “a,” “an” and “the” include plural referents unless the content clearly dictates otherwise. 
         [0031]    The terms “first,” “second,” and the like in the description and in the claims, if any, are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order. It is to be understood that the terms so used are interchangeable under appropriate circumstances such that the embodiments of the invention described herein are, for example, capable of operation in sequences other than those illustrated or otherwise described herein. Furthermore, the terms “include,” “have,” and any variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements is not necessarily limited to those elements, but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. 
         [0032]    The terms “left,” “right,” “front,” “rear,” “top,” “bottom,” “over,” “under,” and the like in the description and in the claims, if any, are used for descriptive purposes and not necessarily for describing permanent relative positions. It is to be understood that the terms so used are interchangeable under appropriate circumstances such that the embodiments of the invention described herein are, for example, capable of operation in other orientations than those illustrated or otherwise described herein. 
         [0033]    All numbers expressing measurements and so forth used in the specification and claims are to be understood as being modified in all instances by the term “about.” 
         [0034]      FIG. 1  shows an exploded perspective view of the relevant parts of a prior art rectangular micro speaker  10 . Speaker  10  comprises a membrane  12  that is typically built out of one or more layers of material, such as, for example, Ethere Ketone (PEEK), Acrylate and/or Thermoplastic Elastomeric (TEP), Polyetherimide (PEI), and/or other materials known in the art. Membrane  12  may also include a membrane plate  14  to stiffen membrane  12 . Speaker  10  furthermore comprises a coil  32  with leads  34 . An electrical signal to drive coil  32  is fed into coil  32  through leads  34 . Coil  32  of assembled speaker  10  is fixed to membrane  12  with an adhesive, such as, for example, glue, tape, or other adhesives known in the art. 
         [0035]    Speaker  10  includes a magnet system  50  comprising a perimeter magnet assembly  52  and a pot assembly  60 . Perimeter magnet assembly  52  includes four magnets  54  arranged on the rectangular sides of the rectangular speaker  10  and ring plate  58  fixed to magnets  54 . Pot assembly  60  includes pot plate  80 , magnet  62  arranged in the center of pot plate  80 , and top plate  64  fixed to magnet  62  opposite pot plate  80 . Perimeter magnet assembly  52  and pot assembly  60  form magnetic field guide  68 . Magnetic field guide  68  guides and focuses the magnetic field of magnets  54  and  62  in an air gap  70  between perimeter magnet assembly  52  and center magnet assembly  60 , into which coil  32  is arranged in the assembled speaker  10 . 
         [0036]    Prior art micro speaker  10  further includes frame  90  to assemble and align membrane  12  with magnet system  50 . Coil  32  fits into air gap  70  and is able to translate up and down within air gap  70  according to the electrical signal fed into coil  32  through leads  34 . Frame  90  typically is made from a molded plastic which enables frame  90  to have a complex surface with openings which permit airflow and fixation of other parts of speaker  10 . The ends of leads  34  of coil  32  are soldered to contact pads  92   t,  that are fixed in to top side of frame  90  during an assembly process. As shown in  FIG. 2A , the bottom side of frame  90  includes contact pads  92   b  which are electrically connected with contact pads  92   t  on the top side of frame  90 . As shown in  FIG. 2B , a further electrical connection is made with flexible printed circuit  94  which includes contact pads  96 . Contact pads  96  of flexible printed circuit  94  are soldered to contact pads  92   b  during an assembly process. The electrical signal to drive coil  32  is fed through flexible printed circuit  94 , contact pads  96 , contact pads  92   b,  contact pads  92   t,  and into leads  34 . Furthermore as shown in  FIGS. 2A and 2B , pot plate  80  includes bottom vents  98  which permit airflow between a back volume  103  (see  FIGS. 3B and 3C ) and the back volume side of the membrane  12 . Bottom vents  98  of prior art speakers  10  are often asymmetrical, potentially contributing to tumbling of membrane  12  which can cause degradation of the acoustic performance and prematurely wear out membrane  12 . Bottom vents  98  permit vibration of membrane  12  according to the electrical signal fed into coil  32 . 
         [0037]    With reference to  FIGS. 3A, 3B, and 3C , prior art micro speakers  10  are typically placed within an enclosure  100 , wherein enclosure  100  provides a back volume  103  for speaker  10 . Enclosure  100  may be formed of two halves like a clamshell and may include first enclosure portion  102   a  and second enclosure portion  102   b.  Speaker  10  is sandwiched between first and second enclosure portions  102   a,    102   b.  Some applications may include an adsorber material in back volume  103 . The adsorber material acts to create a larger effective back volume which can improve acoustic performance and quality. For applications that include an adsorber, a separator  106  is also typically sandwiched between first and second enclosure portions  102   a,    102   b.  Separator  106  includes a population of holes  107  which permit airflow between membrane  12  and adsorber  108  placed in back volume  103 . Holes  107  typically have a maximum dimension smaller than adsorber  108  material filled into an enclosure so that adsorber material does not come into contact with magnets  54 ,  62 , coil  32 , and membrane  12  of speaker  10 . 
         [0038]    In prior art applications, back volume  103  is filled with adsorber  108  through fill hole  104  after first and second enclosure portions  102   a,    102   b  are mated together. After back volume  103  is filled with adsorber  108 , a cover  109  such as a sticker, is placed over hole  104  to seal hole  104 . 
         [0039]    The acoustic performance and quality are highly dependent upon the amount of adsorber  108  filled into back volume  103 . However, filling back volume  103  with adsorber  108  through fill hole  104  is often less than optimal. That is, adsorber  108  may bunch up or unevenly collect in portions of back volume  103  and may prevent filling back volume  103  with the desired amount of adsorber  108  called for in the particular design. This leads to the designed for acoustic performance and quality not being met. Additionally, even if the desired amount of adsorber  108  called for in the particular design is filled into back volume  103 , cover  109  may eventually come loose and adsorber  108  may leak or fall out of back volume  103 . This results in decreased acoustic performance and quality over time. 
         [0040]    The relevant parts of a first embodiment of the invention are shown in  FIGS. 4-11 .  FIG. 4  shows an exploded perspective view of the relevant parts of a rectangular speaker  110 .  FIG. 5  shows a perspective view of an assembly of a coil  132  and flexible printed circuit  136 .  FIG. 6A  shows a top perspective view of the relevant parts of a rectangular speaker  110 .  FIG. 6B  shows a bottom perspective view of the relevant parts of a rectangular speaker  110 .  FIG. 7  shows a side perspective section view of the relevant parts of a rectangular speaker  110 .  FIG. 8  shows a top perspective partial cutaway view of the relevant parts of a rectangular speaker  110 .  FIG. 9A  shows a top perspective view of the relevant parts of a rectangular speaker  110  assembled into a first portion  192   a  of an enclosure  190 .  FIG. 9B  shows a top perspective view of the relevant parts of a rectangular speaker  110  assembled into an enclosure  190 .  FIG. 10  shows a side perspective section view of the relevant parts of a rectangular speaker  110  assembled into an enclosure  190 .  FIG. 11  is a flowchart describing a method of assembling the rectangular micro speaker  110  into an enclosure  190 . 
         [0041]    With reference to  FIG. 4 , speaker  110  comprises a membrane assembly  111 , a collar  116 , a coil assembly  130 , and a magnet system  150 . Membrane assembly  111  includes a membrane  112 , a membrane ring  113  extending around the perimeter of membrane  112 , and a membrane plate  114  to stiffen membrane  112 . Membrane  112  may be built out of one or more layers of material, such as, for example, Ethere Ketone (PEEK), Acrylate and/or Thermoplastic Elastomeric (TEP), Polyetherimide (PEI), and/or other materials known in the art. 
         [0042]    Magnet system  150  comprises a perimeter magnet assembly  152 , a pot assembly  160 , and an air gap  170  formed therebetween. Perimeter magnet assembly  152  includes four magnets  154  arranged on the rectangular sides of the rectangular speaker  110  and ring plate  158  fixed to magnets  154 . Pot assembly  160  includes pot plate  180 , magnet  162  arranged in the center of pot plate  180 , and top plate  164  fixed to magnet  162  opposite pot plate  180 . Perimeter magnet assembly  152  and pot assembly  160  form magnetic field guide  168 . Magnetic field guide  168  guides and focuses the magnetic field of magnets  154  and  162  in an air gap  170  (see  FIG. 7 ) between perimeter magnet assembly  152  and center magnet assembly  160 , into which coil  132  of coil assembly  130  is arranged in the assembled speaker  110 . 
         [0043]    With continued reference to  FIG. 4  and to  FIG. 5 , coil assembly  130  includes coil  132 , leads  134 , and flexible printed circuit  136 . An electrical signal to drive coil  132  is fed into coil  132  through flexible printed circuit  136  and leads  134 . Coil  132  of assembled speaker  110  is fixed to membrane  112  with an adhesive, such as, for example, glue, tape, or other adhesives known in the art. Unlike prior art micro speakers, leads  134  of coil  132  are directly connected to flexible printed circuit  136 . Flexible printed circuit  136  includes a pair of contact pads  138  on a first terminal end of flexible printed circuit  136  which are in electrical communication with contact pads  140  on a second terminal end of the printed circuit  136  opposite the first. The electrical communication between contact pads  140  and  138  may be accomplished using traces and/or vias as is known in the art. Leads  134  are electrically connected by a solder connection to contact pads  138  to permit an electrical signal to flow from a source (not shown) into contact pads  140 , through traces and/or vias in flexible printed circuit  136 , through contact pads  138 , through leads  134  and into coil  132 . It will be understood by those in the art, that in various embodiments, the electrical connection between leads  134  and flexible printed circuit  136  may be accomplished in a variety of ways known in the art, for example, by inserting leads  134  into an electrical connector affixed to flexible printed circuit  136 . 
         [0044]    Unlike prior art micro speaker  10  shown in  FIGS. 1, 2A, and 2B , micro speaker  110  does not require contact pads  92   t  and contact pads  92   b  to be included in frame  90 . By eliminating the additional components required to transmit the electrical signal from the source to coil  132 , the size may be reduced, the component and manufacturing costs may be reduced, and durability and sound quality may be increased for speaker  110  as compared to prior art speaker  10 . For example, by connecting leads  134  directly to contact pads  138  of flexible printed circuit  136 , the number of electrical connections are reduced to one for each lead  134 . 
         [0045]    As shown in  FIGS. 4 and 5 , leads  134  of coil  132  extend from the side of coil  132  proximate flexible printed circuit  136  and each lead  134  forms a short loop. This allows leads  134  to be shorter in length than leads  34  of prior art micro speaker  10 . However, in other embodiments, for example, leads  134  of coil  132  may extend from the side of coil  132  distal flexible printed circuit  136  and loop inward to be electrically connected to contact pads  138  of flexible printed circuit  136 . As shown, leads  134  extend from the bottom of coil  132  and may be substantially horizontal and substantially in-plane with flexible printed circuit  136  when coil is in the rest position. In various embodiments, speaker  110  may also include one or more of the support members for supporting coil  132  and/or leads  134  as described in U.S. Provisional Application 62/147,801, filed on Apr. 15, 2015, entitled “Speaker with Supported Coil Wire,” the entirety of which is incorporated by reference herein. Other features of coil assembly  130  are described in the U.S. Provisional Application filed on Oct. 6, 2015, having Attorney Docket Number 112256-0091, entitled “Electroacoustic Transducer with Flexible Coilwire Connection,” the entirety of which is incorporated by reference. 
         [0046]    With reference to  FIGS. 4, 6A, 6B, 7, and 8 , collar  116  includes a first portion  118  that is substantially horizontal and substantially parallel with pot plate  180 . A substantially rectangular opening  120  is provided in first portion  118  through which coil  132  may translate during operation of speaker  110 . First portion  118  serves as a rim to which membrane ring  113  is affixed typically, for example, by glue or adhesive. Extending downward and substantially perpendicular from the sides of first portion  118  of collar  116  is a second portion, shown as sidewall  122 . Sidewall  122  extends around the perimeter of collar  116 . 
         [0047]    Collar  116  further includes a stabilizing tab  126  extending substantially horizontally from sidewall  122 . As shown in  FIGS. 6A and 7 , stabilizing tab  126  interfaces with flexible printed circuit  136 , serves to stabilize flexible printed circuit  136 , provides protection between the electrical connection between leads  134  and contact pads  138 , and maintains the positions of collar  116  and coil assembly  130  in speaker  110 . Stabilizing tab  126  is affixed to flexible printed circuit  136  using an adhesive  142  (see  FIG. 4 ), such as, for example, glue, tape, or other adhesives known in the art. 
         [0048]    Sidewall  122  includes a population of openings  124  extending through sidewall  122  proximate the corners of collar  116 . Preferably, there are two arrays of openings  124  proximate the corners of collar  116 . Openings  124  are shown as substantially circular holes arranged in rows and columns. Each side of sidewall  122  of collar  116  is shown with thirty (30) openings  124  arranged in two arrays of fifteen (15) openings  124 . In various embodiments, for example, openings  124  may be laser cut into sidewall  122 . Openings  124  serve as side vents which permit airflow between a back volume  196  (see  FIG. 10 ) and the back volume side of membrane  112  (see Arrows A in  FIG. 8 ). As illustrated in  FIGS. 4 and 8 , openings  124  are substantially aligned with the gaps  156  between magnets  154  of perimeter magnet assembly  152  and thus speaker  110  includes a substantially clear air pathway between back volume  196  (see  FIG. 10 ) and the back volume side of membrane  112 . Therefore, openings  124  permit an undistorted vibration of membrane  112  in response to the electrical signal fed into coil  132 . With the inclusion of openings  124  on collar  116 , back vents are not required in pot plate  180  as shown in  FIGS. 2A and 2B . By not requiring back vents on pot plate  180 , the geometry and/or features of pot plate  180  can be simplified as compared to pot plate  80  of prior art speakers, thus reducing component cost. 
         [0049]    It will be understood that the number and/or the size of openings  124  may be altered to provide the appropriate side venting to a back volume (not shown) to achieve the desired acoustic performance for speaker  110 . That is, the total open area of openings  124  may be modified according to the design requirements of a particular application. Likewise, the placement of opening  124  on sidewall  122  is not limited to being adjacent to the corners of sidewall  122  nor substantially aligned with the gaps  156  between magnets  154  of perimeter magnet assembly  152 . For example, openings  124  may be located at the midpoint along one or more sides of sidewall  122 . In other embodiments, for example, openings  124  may be distributed, either evenly or unevenly, along one or more sides of sidewall  122 . Preferably, the open area of openings  124  on each side of sidewall  122  of collar  116  is substantially equal. This permits substantially equal intake and exhaust of air through openings  124  on all sides of sidewall  122  which promotes substantially equal vertical translation of membrane  112  across the entire membrane  112 . That is, this tends to reduce or eliminate tumbling of membrane  112  which, in turn, reduces or eliminates non-uniform stresses upon membrane  112  which could lead to premature failure of membrane  112 . Therefore, by reducing tumbling of membrane  112 , acoustic performance and quality are increased and durability of membrane  112  and speaker  110  are increased. 
         [0050]    As described in greater detail elsewhere herein, speaker  110  may be placed in an enclosure  190  into which an adsorber material may be directly filled. To prevent the adsorber from coming into contact with magnets  154 ,  162 , coil  132 , and membrane  112  of speaker  110 , openings  124  may have a maximum dimension smaller than an adsorber material filled into an enclosure. The adsorber material may be, for example, the zeolite material described in U.S. Published Patent Application 2013/0170687, published on Jul. 4, 2013, entitled “Loudspeaker System with Improved Sound,” the entirety of which is incorporated herein by reference. 
         [0051]    Collar  116  is preferably formed of a sheet of stainless steel having a thickness from about 0.1 mm to about 0.2 mm (e.g., about 0.1 mm, about 0.11 mm, about 0.12 mm, about 0.13 mm, about 0.14 mm, about 0.15 mm, about 0.16 mm, about 0.17 mm, about 0.18 mm, about 0.19 mm, about 0.20 mm). In various embodiments, the thickness of collar 116 may be less than about 0.1 mm. In various other embodiments, the thickness of collar 116 may be greater than about 0.2 mm. It will be understood, that in other embodiments, for example, collar  116  may be formed from a variety of materials including, but not limited to, metals (e.g., steel, aluminum, titanium, magnesium, and alloys thereof), plastics (e.g., acrylonitrile butadiene styrene (ABS), polyvinyl chloride (PVC)), composites (e.g., carbon fiber- and aramid-reinforced polymers), etc. Collar  116  may be formed by, including, but not limited to, stamping, casting, injection molding, additive manufacturing, etc. 
         [0052]    The assembled speaker  110  is shown in  FIGS. 6A, 6B, 7, and 8 . Membrane assembly  111  is affixed to collar  116  which is, in turn, affixed to flexible printed circuit  136  (e.g., by adhesive  142 ) by support tab  126 . Flexible printed circuit  126  is affixed to pot plate  180 , to which perimeter magnet assembly  152  and center magnet  162  are affixed. In various embodiments, for example, collar  116  may also be affixed to pot plate to increase stiffness of speaker  110 . 
         [0053]    Now with reference to  FIGS. 9A, 9B and 10 , assembled speaker  110 , is shown as installed in an enclosure  190 . Enclosure  190  includes a first enclosure portion  192   a  and a second enclosure portion  192   b.  A back volume  196  is defined by first enclosure portion  192   a,  second enclosure portion  192   b,  and speaker  110 . Second enclosure portion  192   b  includes an opening  194  that is substantially the same size as pot plate  180  of speaker  110 . When speaker  110  is assembled into first enclosure portion  192   a  and second enclosure portion  192   b  is placed in first enclosure portion  192   a,  pot plate  180  serves to seal opening  194 . By having pot plate  180  insert into and close opening  194 , the external size of enclosure  190  can be reduced while maximizing the back volume  196  of enclosure  190 . Thus a larger speaker  110  and a larger back volume  196  can be used in a device as compared to a prior art speaker  10  and prior art enclosure  100 . Or, alternatively, a smaller speaker  110  having the same acoustic performance as prior art speaker  10  can be used in a device. 
         [0054]    With continued reference to  FIGS. 9A, 9B, and 10  and with reference to  FIG. 11 , a method of assembling speaker  110  into enclosure  190  and directly filling back volume  196  with an adsorber is described. At step  1100 , speaker  110  is placed into first enclosure portion  192   a  with membrane  112  facing downward. As shown in  FIG. 9A , membrane  112  is in communication with sound path  198  which terminates in side firing port  199  (see  FIG. 10 ). After speaker  110  is placed into first enclosure portion, an open volume remains in first enclosure portion  192   a.  Open volume will become back volume  196  when second enclosure portion  192   b  is placed in first enclosure portion  192   a.  At step  1102 , a desired amount of adsorber material is directly filled into the open volume. Because the entirety of the open volume is easily accessible and because of the side venting provided by openings  124 , the entirety of the adsorber desired or specified for the particular design can be easily filled into enclosure  190 . Because the maximum size of each individual opening  124  is less than the size of the adsorber material, the adsorber can be filled directly against speaker  110  without any risk of adsorber material coming into contact with magnets  154 ,  162 , coil  132 , and membrane  112 . Furthermore, with inclusion of side openings  124  and the size thereof, a separator plate  106  is not required like in speaker  10 . At step  1104 , after the specified amount of adsorber is directly filled into first enclosure portion  192   a,  second enclosure portion  192   b  is placed into first enclosure portion  192   a.  Second enclosure portion  192   b  may then be sealed against first enclosure portion  192   a  and pot plate  180 . Therefore, unlike prior art designs, there is no small fill hole which needs to be sealed with a cover. 
         [0055]    While various steps are described herein in one order, it will be understood that other embodiments of the method can be carried out in any order and/or without all of the described steps without departing from the scope of the invention. 
         [0056]    Although enclosure  190  is illustrated with a sound path  198  terminating in side firing port  199 , it will be understood that in various embodiments, the enclosure of speaker  110  may include a sound path terminating in a top or bottom firing port. Enclosure  190  may further includes a passageway through which flexible printed circuit  136  exits so that it may be connected to a source (not shown) for driving speaker  110 . 
         [0057]    Another embodiment of collar  216  of the invention is illustrated in  FIGS. 12A, 12B  and is described below. Some features of one or more of collars  116  and  216  are common to one another and, accordingly, descriptions of such features in one embodiment should be understood to apply to other embodiments. Furthermore, particular characteristics and aspects of one embodiment may be used in combination with, or instead of, particular characteristics and aspects of another embodiment. 
         [0058]    Collar  216  has a first portion  218  that is substantially horizontal and substantially parallel with a pot plate  180 . A substantially rectangular opening  220  is provided in first portion  218  through which a coil  132  may translate during operation of a speaker  110 . First portion  218  serves as a rim to which the membrane ring  113  of a membrane  112  is affixed typically, for example, by glue or adhesive. Extending downward and substantially perpendicular from the sides of first portion  218  of collar  216  is a second portion, shown as sidewall  222 . Sidewall  222  extends around the perimeter of collar  216 . 
         [0059]    Sidewall  222  includes a population of openings  224  extending through sidewall  222  proximate the corners of collar  216 . Openings  224  are shown as slots arranged in columns. The slot openings  224  are shown as extending from the terminal end of sidewall  222  up toward first portion  218  of collar  216 . In various embodiments, for example, openings  224  may be laser cut into sidewall  222 . Openings  224  serve as side vents which permit airflow between a back volume (not shown) and the back volume side of a membrane  112 . Openings  224  may be substantially aligned with the gaps between magnets  154  of magnet system  150  and thus a speaker may include a substantially clear air pathway between the back volume and the back volume side of membrane  112 . Therefore, openings  224  permit an undistorted vibration of membrane  112  in response to the electrical signal fed into coil  132 . With the inclusion of openings  224  on collar  216 , back vents are not required in pot plate  180  as shown in  FIGS. 2A and 2B . By not requiring back vents on pot plate  180 , the geometry and/or features of pot plate  180  can be simplified as compared to pot plate  80  of prior art speakers, thus reducing component cost. 
         [0060]    Collar  216  further includes a stabilizing tab  226  extending substantially horizontally from sidewall  222 . Stabilizing tab  226  functions the same as stabilizer tab  126  shown in  FIGS. 4, 6A, 6B, and 7 . Stabilizing tab  226  interfaces with flexible printed circuit  136 , serves to stabilize flexible printed circuit  136 , provides protection between the electrical connection between leads  134  and contact pads  138 , and maintains the positions of collar  216  and coil assembly  130  in the speaker. Stabilizing tab  226  is affixed to flexible printed circuit  136  using an adhesive  142  (see  FIG. 4 ), such as, for example, glue, tape, or other adhesives known in the art. 
         [0061]    While embodiments of the audio transducer are shown and described as having a rectangular shape, it will be understood that in other embodiments, the audio transducer may have a variety of shapes, including, but not limited to, circular and ovular. Accordingly, the invention is not limited to audio transducers having a rectangular shape. 
         [0062]    In closing, it should be noted that the invention is not limited to the above mentioned embodiments and exemplary working examples. Further developments, modifications and combinations are also within the scope of the patent claims and are placed in the possession of the person skilled in the art from the above disclosure. Accordingly, the techniques and structures described and illustrated herein should be understood to be illustrative and exemplary, and not limiting upon the scope of the present invention. The scope of the present invention is defined by the appended claims, including known equivalents and unforeseeable equivalents at the time of filing of this application.