Patent Publication Number: US-10785551-B2

Title: Portable loudspeaker

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. patent application Ser. No. 13/909,071, filed on Jun. 3, 2013, the disclosure of which is incorporated herein by reference in its entirety. 
    
    
     BACKGROUND 
     This disclosure relates to audio devices, and in particular to a portable loudspeaker. 
     U.S. Pat. No. 8,098,867 to Hampton et al. discloses an external acoustic chamber ( 220 ) for attachment to a mobile device ( 200 ). The external acoustic chamber ( 220 ) optimizes the audio performance of the mobile device ( 200 ) thus reducing the need for signal equalization and/or hardware to amplify the sound signal. The mobile device ( 200 ) includes a loudspeaker ( 205 ) and a first acoustic chamber ( 207 ) acoustically coupled to the loudspeaker ( 205 ). The external acoustic chamber ( 220 ) comprises at feast a second acoustic chamber ( 222 ) which penetrates the first acoustic chamber ( 207 ) adding volume to the first acoustic chamber ( 207 ). The combined greater volume reduces the dampening of loudspeaker ( 205 ) caused by the pressure in the first acoustic chamber ( 207 ). The result is an improvement in the frequency response of loudspeaker ( 205 ) approaching the natural frequency response of loudspeaker ( 205 ). The at least second acoustic chamber ( 222 ) is sized and shaped so that a first exterior surface portion of the acoustic chamber ( 220 ) covers or is flush with the battery ( 214 ) installed in the housing ( 201 ) of the mobile device ( 200 ). The first, exterior surface portion is substantially aligned with a second exterior surface portion enclosing the at least second acoustic chamber ( 222 ). The effect of the above disclosure is that the mobile device ( 200 ) is made substantially larger and heavier by the addition of the external acoustic chamber ( 220 ). Such an increase in size and weight is not desirable. 
     SUMMARY 
     In one aspect, a portable loudspeaker includes a first electro-acoustic driver which creates sound waves when operated; a housing having a first side to which the driver is secured, and a second side opposite the first side; a first passive radiator secured to the first side of the housing and a second passive radiator secured to the second side of the housing; and a unitary battery module removably secured to the housing in a region substantially between the first and second passive radiators, the battery providing electrical power to the driver, the sound waves from the driver being capable of acoustically energizing the first and second passive radiators. 
     Examples of the first aspect can include one or more the following features. A second electro-acoustic driver secured to the first side of the housing, wherein both the first and second drivers are located on either side of the first passive radiator. The battery module is disposed centrally between the first and second passive radiators. The loudspeaker is configured such that the maximum excursion of at least one of the passive radiators traverses substantially all of the distance between the at least one passive radiators and the battery. The first and second passive radiators comprise a surround for a diaphragm, the surround comprising first and second membrane sections, the first membrane section comprising a concave cross-section and the second membrane member comprising a convex cross-section. The first and second membrane sections of the first and second passive radiators alternative circumferentially along the diaphragm. At least one of the first and second passive radiators comprises a weight adhered to the diaphragm, the weight comprising a plurality of notches, which during a molding process to form the diaphragm fill with the molding material of the diaphragm. A first speaker grille covering the first electro-acoustic driver and the first passive radiator, a front speaker gasket attaching the first speaker grille to the housing; and a series of first energy directors disposed on a first side of the front speaker gasket and extending toward the housing, the first energy directors configured to minimize vibration between the first speaker grille and the housing. A series of second energy directors disposed on a second side of the front speaker gasket opposite the first side and extending toward the first speaker grille, the second energy directors configured to minimize vibration between the front speaker grille and the front speaker gasket. The portable loudspeaker may be configured for a wireless connection to an audio source. A vibrating surface of the first electro-acoustic driver and a vibrating surface of the first passive radiator are substantially coplanar. A vibrating surface of the first and second passive radiators are substantially parallel. The first and second passive radiators vibrate acoustically in phase with each other and mechanically out of phase with each other. The battery module is disposed substantially centrally between the first and second passive radiators. The housing comprises extruded aluminum having a first extruded opening to receive the first and second electro-acoustic drivers and the first passive radiator and a second extruded opening opposite the first extruded opening to receive the second passive radiator. 
     As described in a second aspect, a portable loudspeaker includes a first electroacoustic drivers which creates sound waves when operated; a housing having a first side to which the driver is secured, and a second side opposite the first side; a first passive radiator secured to the first side of the housing and a second passive radiator secured to the second side of the housing, the first and second passive radiators comprising first and second vibrating surfaces which are substantially coplanar; and a unitary battery module removably secured to the housing in a region substantially between the first and second passive radiators, the battery providing electrical power to the driver, the sound waves from the driver being capable of acoustically energizing the first and second passive radiators, 
     Examples of the second aspect can include one or more the following features. The loudspeaker is configured such that the maximum excursion of at least one of the passive radiators traverses substantially all of the distance between the at least one passive radiators and the battery. A second electro-acoustic driver secured to the first side of the housing, wherein both the first and second drivers are located on either side of the first passive radiator. The battery module is disposed substantially centrally between the first and second passive radiators in the region within the housing. The first and second passive radiators vibrate acoustically in phase with each other and mechanically out of phase with each other. 
     According to a third aspect, a portable loudspeaker includes a housing having a first side to which the driver is secured, and a second side opposite the first side; a first passive radiator secured to the first side of the housing and a second passive radiator secured to the second side of the housing, the first and second passive radiators comprising first and second vibrating surfaces which are substantially coplanar; a first electro-acoustic driver located on a first side of the first passive radiator, a second electoacoustic driver located on a second side of the first radiator opposite the first side, the drivers create sound waves when operated; and a unitary battery module removably secured to the housing in a region substantially between the first and second passive radiators, the battery providing electrical power to the driver, the sound waves from the first and second drivers being capable of acoustically energizing the first and second passive radiators. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is perspective view of a portable loudspeaker as seen from the front, top and right sides; 
         FIG. 2  is a perspective view of the portable loudspeaker of  FIG. 1 , with the housing shown as transparent to reveal some of the internal components of the loudspeaker; 
         FIG. 3  is an exploded view of the portable loudspeaker of  FIG. 1 ; 
         FIG. 4  is a more detailed exploded view of the portable loudspeaker of  FIG. 1 ; 
         FIG. 5  a horizontal sectional view along the length of the loudspeaker of  FIG. 1 ; 
         FIG. 6  is a vertical sectional view along the depth of the loudspeaker of  FIG. 1 ; 
         FIGS. 7A through 7G  are various views of a speaker grille gasket of the loudspeaker of  FIG. 1 ; 
         FIGS. 8A through 8E  are various views of an alternative speaker grille gasket of the loudspeaker of  FIG. 1 ; 
         FIG. 9A through 9F  are various views of a passive radiator of the loudspeaker of  FIG. 1 ; 
         FIG. 10  is a perspective view of a charging cradle configured for use with the portable loudspeaker of  FIG. 1 , as seen from the front, top and right sides. 
     
    
    
     DETAILED DESCRIPTION 
     As unitary portable loudspeaker systems become increasingly compact, appreciable challenges arise in establishing a sufficiently large acoustic volume within the system and in providing adequate surface area on the housing of the system in which to locate the radiating surfaces of electro-acoustic drivers and passive radiators, and thereby render high quality audio output. Removable elements such as an internal battery module displace the acoustic volumes and compete for surface area of the portable loudspeaker system. High pressures within the acoustic volume also require robust and resilient seals between the drivers and/or passive radiators and the housing of the system. The examples described herein address the foregoing challenges. 
     With reference to  FIG. 1 , a portable loudspeaker  100  includes a housing  105  and a first grille  110   a  along the front surface. In some examples, the housing is made of extruded aluminum and the first grille  110   a  is made of steel. A series of buttons  115 , extend along a top surface of the loudspeaker  100  control operation of the loudspeaker. In various examples, the buttons are tact switches, manually operable control surfaces, or a series of adjacent control segments of a touch screen, for example. A “Power” button  115   a  is pressed to turn the loudspeaker  100  on or off. A “Mute” button  115   b  can be pressed to mute or un-mute the loudspeaker  100 . A “Vol−” button  115   c  is pressed to decrease the volume of the loudspeaker  10 . A “Vol+” button  115   d  is pressed to increase the volume of the loudspeaker  10 . A “Bluetooth” button  115   e  is pressed to select a Bluetooth® audio source (not shown) which can provide an audio signal to the loudspeaker  100  via a wireless connection. The loudspeaker  100  can wirelessly receive audio signals from a Bluetooth® audio source device (not shown). In one example, the Bluetooth® button  115   e  can also be pressed for a predetermined period of time to place the loudspeaker  100  into discoverable mode for pairing with a Bluetooth® audio device. An “Aux” button  115   f  is pressed to select an auxiliary audio source (not shown) which can provide an audio signal to the loudspeaker  100  via a hardwired electrical connection. A lens  120  extends along the series of button and covers a series of iconography which illuminate to denote various operation statuses and modes of the loudspeaker  100 , including for example, low battery level, paired with a Bluetooth® source. The iconography may be formed on the lens  120  using an in-molded label process (IML) in some examples. A DC-power connector  125  can be connected to a power supply (not shown) to supply power to the loudspeaker  100  or to charge a rechargeable battery (discussed below) that is secured to the housing  105 . A portable audio source (not shown) can be connected to an aux in connector  130  via a 3.5-mm stereo cable in one example. 
     Referring now to  FIG. 2 , the housing  105  is depicted transparently and the first speaker grille  110   a  is removed to show internal components of the loudspeaker  100 . The loudspeaker  100  includes a first electro-acoustic driver  150   a  which is driven by a first channel audio signal and a second electro-acoustic driver  150   b  which is driven by a second channel audio signal. In one example, the first channel audio signal is a left channel audio signal and the second channel audio signal is a right channel audio signal. The drivers  150   a ,  150   b  are all secured to the housing  105  and create sound waves when operated. In one example, a first passive radiator  160   a  (sometime referred to as a “drone”) is secured to the housing  105  and is located on a same side of the housing  105  as the first and second drivers  150   a ,  150   b.    
     In one example, the acoustic enclosure of the loudspeaker  100  is dimensioned so that when the electro-acoustic drivers  150   a ,  150   b  are coupled to and driven by a source of audio signals, the passive radiators  160  vibrate acoustically in phase with each other and mechanically out of phase with each other. 
     In one example, the first and second drivers  150   a ,  150   b  are disposed on opposite ends of the housing  105 , and the first passive radiator  160   a  is positioned therebetween. Each of the drivers  150   a ,  150   b  and the passive radiator  160   a  radiate acoustic energy in the same general direction. The housing  105  also contains a number of circuit boards including a main circuit board  170  which includes the series of buttons  115 , an amplifier board  175  which includes an amplifier (not shown), and a boost board  180  which includes a boost converter (not shown), and an input/output board  185  which includes the DC-power connector  125  and the aux in connector  130 . A removable unitary battery module  190  is disposed between the first and second drivers  150   a ,  150   b  and substantially behind the first passive radiator  160   a.    
     Referring now to  FIGS. 3 and 4 , additional components of the loudspeaker  100  are shown. A second speaker grille  110   b  of comparable size and shape to the first grille  110   a  is positioned opposite the first grille  110   a  and extends along the rear portion of the loudspeaker  100 . A front baffle  195   a  attaches to a front portion of the housing  105  via a number of baffle fasteners  197   a , such as thread-rolled hex screws for example, which attach to a series of extruded bosses  198  depending from the housing  105 . The fasteners  197   a  extend through a series of holes in the first electro-acoustic drivers  150   a ,  150   b  and secure the drivers  150   a ,  150   b  to the housing  105 . A rear baffle  195   b  attaches to a rear portion of the housing  105 , opposite the front baffle  195   a , via a number of baffle fasteners  197   b , such as thread-rolled hex screws, for example, which attach to the series of extruded bosses  198  depending from the housing  105 . A front speaker gasket  200   a  attaches to the front baffle  195   a  and a rear speaker gasket  200   b  attaches to the rear baffle  195   b . The button cluster  115 , the lens  120  and a lens assembly  205  are disposed in an opening in the top portion of the housing  105 . A battery access door (or foot)  210  is removably attached to a bottom portion of the housing  105  to permit access, insertion and removal of the battery  190 . In some examples, the door  210  remains coupled to the housing  105  via a tether  215 . The access door  210  can be made of rubber, for example, and also function as a compliant, non-skid base for the loudspeaker  100  when the unit is placed upon a horizontal level surface. In some examples, the housing  105 , together with the baffles  195   a ,  195   b , the front and rear speaker gaskets  200   a ,  200   b , the first and second drivers  150   a ,  150   b , and the battery  190  define a substantially airtight acoustic volume within the housing  105 . In one example, the acoustic volume is between 100 and 200 cubic centimeters (cc), in other examples, the acoustic volume is between 100 and 150 cc, and in still other examples, the acoustic volume is between 120 and 130 cc. In this example, the housing  105  along with the above-described components bound an internal three-dimensional acoustic volume in the approximate form of a parallelepiped. In other examples, the bounded acoustic volume is a hexahedron, a polyhedron, a cylinder, a portion of a sphere, a conic section, a prism, or other shape. 
     During operation of the loudspeaker  100  and in some examples, the maximum pressure of the acoustic volume (i.e., the internal box pressure) is between 0.25 and 1.5 pounds per square inch (psi), in other examples, the pressure is between 0.5 and 1.25 psi, and in still other examples, the pressure is between 0.75 and 1.0 psi. The drivers  150   a ,  150   b  acoustically energize the acoustic volume inside the loudspeaker  100  which causes the first and a second passive radiators  160   a ,  160   b  to vibrate and emit sound waves. In some examples, the vibrating surface of the first and second passive radiators  160   a ,  160   b  are substantially parallel. In some examples, a vibrating surface of the first electro-acoustic driver  150   a  and a vibrating surface of the first passive radiator  160   a  are substantially coplanar. In other examples, the vibrating surfaces of the first and second electro-acoustic drivers  150   a ,  150   b  and a vibrating surface of the first passive radiator  160   a  are all substantially coplanar. 
     The front and rear speaker grilles  110   a ,  110   b  are attached to the front and rear speaker gaskets  200   a ,  200   b , respectively. In some examples, a first adhesive ring  225   a  ( FIG. 4 ), such as a VHB pressure sensitive adhesive for example, configured to correspond to the perimeter of the first passive radiator  160   a  provides adhesion between the front grille  110   a  and the front speaker baffle  195   a . Similarly, a second adhesive ring  225   b  ( FIG. 4 ) configured to correspond to the perimeter of the second passive radiator  160   b  provides adhesion between the rear grille  110   b  and the rear speaker baffle  195   b . The front and rear speaker grilles  110   a ,  110   b  are substantially acoustically transparent and provide ornamental cover and protection for the first and second transducers  150   a ,  150   b  and the first and second passive radiators  160   a ,  160   b . The battery module  190  is removably attached to an opening in a lower portion of the housing  105  via a series of fasteners  235  which extend through a series of corresponding holes in a flange  240  extending along the base of the battery module  190 . When sealed to the housing  105 , the battery module  190  defines a portion of the acoustic volume, in some examples. A wiring harness  250  electrically connects various components within the housing  105 . The harness  250  may be dressed with a foam layer to mitigate unwanted vibration or buzzing while the loudspeaker  100  is in operation, in some examples. In still other examples, one or more foam elements  255  can be included at various locations within the housing  105  to mitigate unwanted vibration or buzzing while the loudspeaker is in operation. Circuit board connectors  260   a  and  260   b  electrically connect the circuit boards of the loudspeaker  100 . Connector  260   a  electrically connects the main board  170  with the boost board  180 . Connector  260   b  electrically connects the main board  170  with the I/O board  185 . The connectors  260   a ,  260   b  can be for example, flat flexible connectors or flexible PCB type connectors. 
     Referencing  FIGS. 5 and 6 , the removable unitary battery module  190  is disposed between the first and second drivers  150   a ,  150   b  and between the first and second passive radiators  160   a ,  160   b . In some examples, the battery module  190  substantially extends from a lower portion of the housing  105  to an upper portion of the housing  105  and is located centrally between the first and second passive radiators  160   a ,  160   b . Locating the battery module  190  between the passive radiators  160   a ,  160   b  provides a reduction in the overall size of the loudspeaker  100  for a given acoustic volume and still accommodating multiple acoustic elements such as the first and second drivers and the first and second passive radiators  160   a ,  160   b  on the housing  105 . 
     In some examples, the passive radiators  160   a ,  160   b  are driven with parallel and preferably coaxial, directions of motion which are acoustically in phase with each other and mechanically out of phase with each other. Using two passive radiators within a single housing can be advantageous because the inertial forces associated with passive radiators may be made to cancel, and the size of each individual passive radiator may be made smaller. This is especially advantageous for small, highly portable devices, since the surface area of the housing of such devices may not be large enough to accommodate a single passive radiator. 
     Refer now collectively to  FIGS. 7A-7G  and  FIGS. 8A-8D  for additional details on the rear speaker gasket  200   b  and the front speaker gasket  200   a , respectively. The speaker gaskets  200   a ,  200   b  are positioned between the speaker grilles  110   a ,  110   b  ( FIGS. 3 and 4 ) and the front and rear speaker baffles  195   a ,  195   b  ( FIG. 4 ), respectively and serve to minimize vibration between the grilles  110   a ,  110   b  and the baffles  195   a ,  195   b , respectively. In some examples, the gaskets  200   a ,  200   b  may be configured to secure the front and rear speaker grilles  110   a ,  110   b  to the front and rear speaker baffle  195   a ,  195   b.    
     In some examples, the gaskets  200   a ,  200   b  are made from silicone rubber, 70 durometer. Each of the gaskets  200   a ,  200   b  includes a center opening  270   a ,  270   b  to accommodate the first and second passive radiators  160   a ,  160   b , respectively. The front speaker gasket  200   a  also includes a first driver opening  280   a  and a second driver opening  280   b  to accommodate the first electro-acoustic driver  150   a  and second electro-acoustic driver  150   b , respectively. A front perimeter ring  275   a ,  275   b  extends along the outer perimeter and includes an undercut  280   a ,  280   b  to receive and engage the outer perimeters of the front and rear speaker grilles  110   a ,  110   b  ( FIGS. 3 and 4 ). In some examples, slots  290   a  are located along the outer perimeter of the gasket  200   a  to receive tabs  112   a  ( FIGS. 3 and 4 ) extending from the outer perimeter of the front speaker grille  112   a . Similarly, slots  290   b  are located along the outer perimeter of the gasket  200   b  to receive tables  112   b  ( FIGS. 3 and 4 ) extending from the outer perimeter of the rear speaker grille  112   b.    
     In some examples, the grilles  110   a ,  110   b  are made of thin steel and include micro-perforations for acoustic transparency. The physical properties of the steel grilles  110   a ,  110   b  yields a high Q value which may result in undesirable vibratory engagement with the front and rear speaker gaskets  200   a ,  200   b , respectively and/or with the front and rear speaker baffles  195   a ,  195   b , respectively. This vibratory engagement between the components of the loudspeaker can lead to unwanted buzzing. To reduce or eliminate this buzzing which may otherwise be especially acute in an acoustic volume with very high internal pressures and bound by multiple components, the rear gasket  200   b  includes a first set of energy directors  300  located within a first region  305  and second set of energy directors  310  located within a second region  315 . With specific reference to  FIGS. 7F and 7G  and in some examples, the reverse side of rear gasket  200   b  also includes energy directors  320  which extend from rectangular extrusions  325  which depend from the rear gasket  200   b  and properly position the directors  320  to engage the opposing surface of rear speaker baffle  195   b  and minimize unwanted buzzing and vibration. 
     Similarly, the front gasket  200   a  includes a third set of energy directors  330  and a fourth set of energy directors  335  located on opposite sides of the center opening  270   a.    
     In some examples, the number, size and configuration of the energy directors  300 ,  305 ,  330 ,  335  correspond to the location of the features on opposing surfaces of the front and rear baffles  195   a ,  195   b . In the example shown in  FIG. 8E , the energy directors  300 ,  305 ,  330 ,  335  can have a triangular cross-section, but other cross sectional are contemplated including square, hemispherical, concave, and convex. Each set of energy directors  300 ,  305 ,  330 ,  335  can be arranged in a parallel, orthogonal, or other configuration to properly engage the opposing surfaces and minimize unwanted buzzing and vibration. In some examples, the energy directors  300 ,  305 ,  330 ,  335  are forced into compression by components adjacent to the baffles  195   a ,  195   b  and thereby substantially immobilize the baffles  195   a ,  195   b  to minimize buzzing. 
     Referring now collectively to  FIGS. 9A-9F , further details of the passive radiator  160  are shown. Utilizing passive radiators is advantageous over using ported acoustic structures in some applications to augment low frequency output because passive radiators are less prone to viscous loses, to port noise, and to other losses associated with fluid flow than typical port structures. Further, passive radiators can be configured to occupy less space, which is particularly important when passive radiators are used in compact loudspeaker housing. Passive radiator  160  includes an outer frame  340  having a series of holes  345  through which certain of baffle fasteners  197   a ,  197   b  extend and engage the extruded bosses  198  of the housing  105  to secure the passive radiator  160  to the front and rear baffles  195   a ,  195   b  and to bound a portion of the acoustic volume of the loudspeaker  100 . In some examples, the outer frame  340  is formed from a thermoplastic polyester engineering resin, such as polybutylene terephthalate resin, 30 percent glassfilled, sold by Celanese, 222 W. Las Colinas Blvd, Suite 900N, Irving Tex. 75039. 
     A surround  350  includes a plurality of generally planar membrane sections  355  that extend radially from an outer edge  357  connecting the frame  340  to an inner edge  358 . In some examples, the membrane sections are arcuate, concave shaped (membrane section  355 ) and arcuate, convex shaped (membrane section  360 ). A radial rib  365  extends between the membrane sections  355 ,  360  and from the inner edge  358  to the outer edge  357  of the surround  350 . The inner edge  358  of the surround  350  connects to a diaphragm (or piston)  359 , which reciprocates back and forth to produce acoustic waves. The movement of the diaphragm is also referred to as excursion. When at rest, the diaphragm  359  is in a neutral position and when the diaphragm  359  is at maximum and minimum amplitude, the diaphragm can be referred to as being at maximum excursion. In some examples, the surround  350  also includes a linear, concave shaped membrane section  370  and a linear, convex shaped membrane section  375 . A radial rib  380  extends between the membrane sections  370 ,  375  and from the inner edge  358  to the outer edge  357  of the surround  350 . In some examples, the membrane sections alternate a circumferential direction from being concave membrane sections  355 ,  360  to convex membrane sections  360 ,  375 . In some examples, the surround  350  is generally oval in shape and includes four linear membrane sections and four arcuate membrane sections. The diaphragm can be formed from the same materials as the frame, a polybutylene terephthalate resin as described above. In some examples, the diaphragm  359  includes a weight (or mass)  385 , which is formed from a stiff material such as steel. The steel weight has a mass of between 20 and 50 grams in some examples, between 30 and 50 grams in other examples, and between 40 and 45 grams in still other examples. The steel weight  385  can be inserted molded into the diaphragm  359 . As shown in  FIG. 9A  and in some examples, the insert molding process can include a molded cap feature  390  to reinforce the adhesion between the weight and the diaphragm  359 . The weight  385  can include a blind hole  395  for retrieval and placement of the weight during the assembly process. In some examples, the inclusion of the weight  385  permits tuning of the passive radiator  160  a desired frequency range. In some examples, the passive radiator  160  of the loudspeaker  100  is tuned to a frequency range of between 60 and 100 Hz, and other examples, the passive radiator  160  is tuned to a frequency range of between 65 and 85 Hz, and in still other examples, the passive radiator is tuned to a frequency range of between 65 and 75 Hz. 
     With particular reference to  FIG. 9F , the weight  385  of the diaphragm  359  includes a series of notches  400  into which the molded material of the diaphragm  359  flows to form a series of dovetail joints  405  between the notches  400  of the diaphragm  359  and the weight  385 . The molded cap features  390  are formed atop the dovetail joints  405  to further reinforce the adhesion between the diaphragm  359  and the weight  385 . The weight  385  of the diaphragm  359  also includes a series of circumferential chamfers  410  which permit the material of the diaphragm  359  to more securely retain the weight  385  while the diaphragm is subject to reciprocal movement. A circumferential groove  415  extends along one or both sides of the diaphragm  359  and is engaged by a corresponding circumferential ridge in the surround  350  to enhance the bond between the surround  350  and the diaphragm  359 . A circumferential groove  420  extends along the outer frame  340  and is engaged by a corresponding circumferential ridge in the outer edge  357  of the diaphragm  350  to enhance the bond between the surround  350  and the outer frame  340 . The bonds between the weight  385  and the diaphragm  359 , between the diaphragm  359  and the surround  350 , and between the surround  350  and the outer frame are formed by two or three-shot injection molding processes, for example. 
     Referring now to  FIG. 10 , a charging cradle (or docking station)  500  is configured for coupling with the loudspeaker  100 . The charging cradle  500  includes a housing  503  having a recess region  505  of the charging cradle  500  is configured to receive the lower surface of the housing  105  and accommodate the battery door  210  which can protrude from the surface of the housing  105  in some examples. Engagement strips  510   a ,  510   b  extend along the edges of the cradle  500  on opposite sides of the recess  505  and are configured to engage the lower surface of the housing  105 . The strips  510   a ,  510   b  are made of a compliant material such as rubber, in some examples, to secure and stabilize the loudspeaker  100  when placed in the cradle  500 . A DC-power connector  515  can be connected to a power supply (not shown) to supply power to the loudspeaker  100  or to charge the rechargeable unitary battery module  190 . In some examples. The power connector  515  can accommodate the same power supply as the DC-power connector  125  ( FIG. 1 ). Electrical contact pins  520  extend from one end of the charging cradle  500  and are configured to engage corresponding electrical contact pads (not shown) on the lower surface of the housing  105  to provide electric power to the loudspeaker  100 . In some examples the contact pins  520  are spring-loaded to provide an upward bias toward the contact pads on the housing  105  to establish and maintain physical contact between the opposing contact pins  520  and the contact pads. The contact pins  520  are located on an input/output board  525  (shown in phantom) inside the housing  503 . An alignment pin  530  extends upward from the housing  503  is configured to engage with a corresponding recess (not shown) in the lower surface of the housing  105  of the loudspeaker to ensure that the contact pins  520  are seated properly against the contact pads of the housing  105  when the loudspeaker is placed upon the charging cradle  500 . In some examples, multiple alignment pins  530  may be used, on the same or opposite ends of the housing  503  to engage corresponding recesses (not shown) in the lower surface of the housing  105 . 
     A number of implementations have been described. Nevertheless, it will be understood that additional modifications may be made without departing from the spirit and scope of the inventive concepts described herein, and, accordingly, other embodiments are within the scope of the following claims.