Abstract:
A low profile loudspeaker transducer is presented with an arrangement of placing the motor up near or into the inside concave portion of a convex dome or inverted convex cone diaphragm. In some preferred embodiments the low profile structure is facilitated by an inverted placement of the spider suspension above the plane of the surround suspension to stabilize the voice coil during excursion while supporting a low profile structure. Additionally, in numerous embodiments a coupling structure is utilized between the voice coil former and the diaphragm to create a broad surface area connection to the diaphragm to create a stiffer structure and minimizing breakup modes and creating a more robust mechanical structure to withstand greater output capability.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application is related to and claims the benefit of U.S. provisional application Ser. No. 61/895,653 filed on 25 Oct. 2013, the contents of which are herein incorporated by reference in their entirety. 
    
    
     TECHNICAL FIELD 
     This invention is in the category of electro-acoustical transducers, more specifically, it is in the category of transducers utilized in loudspeaker systems. 
     BACKGROUND 
     In the audio field it is desirable for loudspeakers to be configured for utilization in smaller and thin form-factor products while maintaining fidelity. 
     The modern consumer electronics market demands integrated loudspeakers within audio products with more and more functions (such as: wireless connection chip sets; larger user interfaces; audio signal processing modules; amplification; rechargeable batteries; etc.) all packaged within compact designs. These constraints generally lead to increasing the size of the associated electronics and reducing the dimensions of the package size dedicated to the loudspeaker enclosure volumes. Additionally, there are a number of other applications where shallow cabinet designs are also incorporated, such as those within very thin television screens where a considerable reduction of the effective cabinet depth and volume can compromise the performance of the transducers. 
     Small transducers are commonly chosen as a solution for such systems since they require lesser acoustic volume than conventional-sized speakers. Nevertheless, it is well known that small transducers present poor efficiency and limited output when reproducing low frequencies at high levels as a consequence of compromised parameters, including limited diaphragm surface area and cubic volume displacement. 
     There is a need for an improved transducer that can be incorporated into smaller or thin profile audio products while achieving the desired acoustical output and high fidelity. 
     BRIEF SUMMARY OF THE INVENTION 
     With the invention is created a simple and effective transducer, which can maintain the diaphragm surface area and displacement of the conventional-sized transducers while significantly reducing the transducer height profile. In a preferred embodiment the low profile loudspeaker transducer may incorporate an inverted relationship between the surround suspension and the spider suspension with the spider suspension placed above the surround suspension housed within the volume of a projecting dome or inverted diaphragm, allowing a shallower structure while maintaining stability and reducing rocking of the voice coil in the voice coil gap during diaphragm excursions. In many of the preferred embodiments a coupling member acts as an intermediate connector between the voice coil former and the diaphragm, providing an increased contact surface area attachment and support to the diaphragm. These and other forms and advantages will become apparent with the ongoing specification disclosed below. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The figures depict preferred embodiments of the present invention for the purposes of illustration only. One skilled in the art will readily recognize from the following discussion that alternative embodiments of the structure and methods illustrated herein may be employed without departing from principles of the invention described. 
         FIG. 1A  is a cut-away view of a first example loudspeaker transducer of the invention; 
         FIG. 1B  is a cross-sectional view of another example loudspeaker transducer of the invention; 
         FIG. 2  is a close-up cut-away view of the first example loudspeaker transducer of the invention; 
         FIG. 3  is a cut-away view of a second example loudspeaker transducer of the invention; 
         FIG. 3A  is a close-up cut-away view of the second example loudspeaker transducer of the invention; 
         FIG. 4  is a cut-away view of a third example loudspeaker transducer of the invention; 
         FIG. 4A  is a close-up cut-away view of the third example loudspeaker transducer of the invention; 
         FIG. 5  is a cut-away view of a fourth example loudspeaker transducer of the invention; 
         FIG. 6  is a cut-away view of a fifth example loudspeaker transducer of the invention; 
         FIG. 6A  is a close-up cut-away view of the fifth example loudspeaker transducer of the invention; 
         FIG. 7  is a cut-away view of a sixth example loudspeaker transducer of the invention; 
         FIG. 7A  is a close-up cut-away view of the sixth example loudspeaker transducer of the invention; 
         FIG. 8  is a cut-away view of a seventh example loudspeaker transducer of the invention; 
         FIG. 8A  is a close-up cut-away view of the seventh example loudspeaker transducer of the invention; 
         FIG. 9  is a cut-away view of an eighth example loudspeaker transducer of the invention; 
         FIG. 10  is a cut-away view of a ninth example loudspeaker transducer of the invention; 
         FIG. 10A  is a close-up cut-away view of the ninth example loudspeaker transducer of the invention; 
         FIG. 11  is a close-up cut-away view of a tenth example loudspeaker transducer of the invention; 
         FIG. 12  is a cross-sectional view of an eleventh example loudspeaker transducer of the invention; 
         FIG. 12 a    is a view of a diaphragm component of the eleventh example loudspeaker transducer of the invention; 
         FIG. 13  is a cross-sectional view of a twelfth example loudspeaker transducer of the invention; 
         FIG. 14  is a cross-sectional view of a thirteenth example loudspeaker transducer of the invention; 
         FIG. 15  is a cross-sectional view of a fourteenth example loudspeaker transducer of the invention; 
         FIG. 16  is a cross-sectional view of a fifteenth example loudspeaker transducer of the invention; 
         FIG. 17  is a cross-sectional view of a sixteenth example loudspeaker transducer of the invention; 
         FIG. 18  is a cross-sectional view of a seventeenth example loudspeaker transducer of the invention; and 
         FIG. 19  is cut-away view of an eighteenth example loudspeaker transducer of the invention. 
     
    
    
     DETAILED DESCRIPTION 
     The mechanical and magnetic structures of a loudspeaker transducer constructed in accordance with, and embodying, the principles of the present invention may take many forms depending on factors such as the nature of the system packaging, the desired frequency response, output capability, and/or the level of linearity that is considered desirable. The target price of a particular magnetic transducer of the present invention will also be a factor, with improved frequency response, maximum output capability, and increased linearity being generally associated with increased cost. 
     Accordingly, a number of different examples of the present invention will be described below. In the following discussion, elements that are or may be common among the various examples may be assigned the same reference character. 
     Referring initially to  FIGS. 1 and 1A , depicted therein is a first example of a preferred embodiment of low profile loudspeaker transducer  10   a  of the present invention. The first example transducer  10   a  comprises a frame  11  which is coupled to T-Yoke  12 , preferably constructed of ferrous material and in this example is shown to be formed with vented pole piece opening  22 . This and other embodiments may be constructed with or without a vented opening in the Y-Yoke. An connecting spacer  11   a  may be used as an intermediary coupling plate interfacing with the back plate  12   a  of T-Yoke  12  and magnet structure  13 , which is shown in  FIG. 1  with two stacked ring magnets and in  FIG. 2  with 1 ring magnet, which may consist of ceramic or ferrite materials, but may incorporate any of a wide variety of magnet materials normally utilized in the field loudspeaker transducers. 
     Preferably ferrous, top plate  14  is coupled to the top of magnet structure  13  forming a magnetic circuit with, preferably ferrous, T-Yoke  12  and back plate  12   a . Diaphragm  18  is shown in this embodiment in  FIGS. 1A and 1B  as a seamless, convex dome connected to frame  11  through concave or convex form (inverted and non-inverted forms respectively), compliant surround suspension  16 . The present invention does not restrict the shape of the surround thus, any surround form traditionally implemented in acoustic transducers can be considered, like multi-roll surround, double surround or single surround forms. That is,  FIGS. 1A and 1B  show a single surround  16 . However, in other embodiments of the invention, the transducer  10 A may include one or more additional surround suspensions disposed radially outward of the illustrated surround  16  and/or radially inward thereof. The additional surround suspension(s) may be shaped similarly to or differently from the surround suspension  16 . Moreover, the surround suspension  16  and/or any additional surround suspensions can possess any desirable shape. For example, the surround suspensions may have a convex or concave curvilinear cross-sectional shape as shown respectively in  FIGS. 1A and 1B  or, alternatively, the surround suspensions may have a linear cross-sectional profile or a profile having both linear and curvilinear aspects. Surround suspension  16  is shown here with ribs  16   b  in  FIGS. 1A and 1B , but the surround suspension may be configured with or without ribs, and surround suspension  16  may also be configured as a non-inverted, convex form, as shown as  16   a  in  FIG. 3 . 
     Diaphragm  18  is coupled to voice coil former  21  through coupler  20 , which in connected between diaphragm  18  and voice coil former  21 . In this preferred embodiment, voice coil former  21  is not directly connected to diaphragm  18 . Electrically conductive voice coil  19  is attached to voice coil former  21  and suspended in a magnetic field gap between top plate  14  and the top of T-Yoke  12  without being in contact with T-Yoke  12  and top plate  14 . 
     Diaphragm  18  is also attached to, and suspended by, spider suspension  17 , which is attached to top plate  14 , and positioned in a plane above surround suspension  16  to provide stability to diaphragm  18  to minimize rocking of the voice coil  19  during dynamic excursions of diaphragm  18 .  FIG. 1B  exhibits a ring separator  25  which connects the inner periphery of the spider suspension  17  to the top plate  14 . This ring separator helps to control the spider suspension fixation points both to the diaphragm  18  and the magnetic motor structure. In the illustrated exemplary embodiment, the ring separator  25  is disposed on top of the top plate  14  and extends annularly thereon around the voice coil former  21  and around the electrically conductive voice coil  19 . The ring separator has a generally square cross-sectional shape and may include a seat on its upper surface for receiving and retaining an end of the spider suspension  17 . The ring separator  25  may extend continuously or discontinuously around the voice coil former  21  and it may possess a cross-sectional shape having curvilinear and/or rectilinear aspects. The ring separator  25  may extend upon the top plate  14  in an annular fashion, as illustrated, or in any other desired geometry, e.g., pentagon, hexagon, oval, diamond shape, etc. 
     Input terminal  15  is adapted to receive an audio input signal and conductive wires (not shown) connect input terminal  15  to voice coil  19 . 
       FIG. 2  is a close up cutaway of the same basic device of  FIG. 1  showing in expanded detail an example of coupler  20  and how it interfaces with voice coil former  21 . For illustrative purposes, diaphragm  18  is spaced away from coupler  20 . It can be seen that coupler  20  has a broader surface area than the top of voice coil former  21 , such that upon being coupled to the diaphragm, coupler  20  creates a larger connection interface with greater diaphragm/coupler integrity, less diaphragm breakup and more pistonic diaphragm mobility over a greater bandwidth. Coupler  20  can be directly connected to diaphragm  21  or can be coupled through a compliant or damped interface material. Coupler  20  can also have different regular or irregular geometries for its outer edge, it cannot only be shaped in a circle but it can exhibit a pentagon, hexagon and so forth. 
       FIG. 3  shows a cut-away view and  FIG. 3A  a close up view that depicts a second example low profile loudspeaker transducer device  10   b . The second example  10   b  is similar to the device in  FIG. 1  but with surround  16   a  shown as a non-inverted, convex configuration, and dome diaphragm  18   a  is a two-part diaphragm, including a central cutout opening  28  with central dust cap cover  24  to complete the diaphragm  18   a , and the diaphragm  18   a  being attached to coupler  20  and convex central dust cap  24  being attached to either one or both of coupler  20  and voice coil former  21 . 
       FIG. 4  shows a cut-away view and  FIG. 4A  a close up view that depicts a third example low profile loudspeaker transducer device  10   c . The third example  10   c  is essentially the same as the device of  FIG. 1  but with surround suspension  16   a  shown as a non-inverted, convex configuration. Throughout the various examples the inverted, concave surround suspension and non-inverted convex surround suspension may be used interchangeably. Device  10   c  is optimized for use as a woofer or subwoofer application for reproducing low frequencies which may demand greater excursions of the diaphragm  18  for which greater linear excursion can be realized with the application of dual spider suspensions  17   a  and  17   b  attached to the outer portion of diaphragm  18  and to ring separator  25 , which is mounted on top plate  14 . Here, the top plate  14  can include a seat for receiving and retaining the ring separator  25 . In the illustrated embodiment, the ring separator  25  is an annular shaped member with a generally rectilinear cross-sectional profile having one of the spider suspensions  17   a  mounted on an upper side of the separator  25  and the other suspension  17   b  mounted on a lower side of the separator  25 . As discussed with reference to  FIG. 1B , the ring separator  25  can include any desired cross-sectional shape and can traverse across the top plate  14  in any desired configuration to provide continuous or discontinuous attachment of the spider suspensions. The dual spider suspension  17   a  and  17   b  acts as a more stable centering device, maintaining positioning of voice coil  19  and keeping it from rubbing against top plate  14  during large signal low frequency excursions. 
       FIG. 5  shows a cut-away view that depicts a fourth example low profile loudspeaker transducer device  10   d . The fourth example  10   d  is essentially the same as the device of  FIG. 1  but with surround suspension  16   a  shown as a non-inverted, convex configuration and magnet structure  13  including two ring magnets  13   a  and  13   b  with ring magnet  13   b  having a greater outside diameter, greater amount of magnet material and greater magnetic energy such that the magnet structure  13  has greater total magnetic energy. This may be used to increase total magnetic energy or to create greater clearance for greater excursion of diaphragm  18  and spider suspension  17  relative to top plate  14  and top magnet  13   b.    
       FIG. 6  shows a cut-away view and  FIG. 6A  a close up view that depicts a fifth example low profile loudspeaker transducer device  10   e . Referring to the device in  FIG. 1 , the fifth example  10   e  is incorporates the differences of surround suspension  16   a  shown as a non-inverted, convex orientation and diaphragm  18   b  has an extended outer diameter  18   c  extending beyond the point of attachment of surround suspension  16   a  to diaphragm  18   b . Additionally, loudspeaker transducer  10   e  utilizes the larger diameter diaphragm extension to advantage by positioning the stabilizing spider suspension  17   c  attachment to diaphragm extension  18   c  below that of surround suspension  16   a.    
     In the various preferred embodiments of the invention the spider suspension  17   c  may be attached or positioned above or below the plane of the surround suspension  16   a  and in certain embodiments may be attached or positioned substantially in the same plane as the surround suspension  16   a . As seen in  FIG. 18 , a spider suspension  31  may be place well below the surround suspension  16 , even on the bottom of the transducer behind back plate  12   b.    
       FIG. 7  shows a cut-away view and  FIG. 7A  a close up view that depicts a sixth example low profile loudspeaker transducer device  10   f . The sixth example  10   f  is similar to the device in  FIG. 1  but with surround  16   a  shown as a non-inverted, convex configuration, and convex dome diaphragm  18   a  including a central cutout opening  28  with central flat dust cap cover  24  mounted to complete the diaphragm  18   a . The diaphragm  18   a  is attached to coupler  20  and flat central dust cap  24  may be attached to either one or both of diaphragm  18   a  and voice coil former  21 . 
       FIG. 8  shows a cut-away view and  FIG. 8A  a close up view that depicts a seventh example low profile loudspeaker transducer device  10   g . The seventh example  10   g  is similar to the device in  FIG. 6 , but is configured as a low profile coaxial transducer with a high frequency tweeter transducer  27  mounted in the opening  28  cut out of diaphragm  18   a . The tweeter  27  may be mounted on top of T-Yoke  12  and in vented pole piece opening  22 , spaced away from the inner surface of voice coil former  21 . Diaphragm  18   a  is attached to coupler  20 , and coupler  20  is attached to voice coil former  21 . 
       FIG. 9  shows a cut-away view that depicts an eighth example low profile loudspeaker transducer device  10   h . The fourth example  10   h  is similar to the device of  FIG. 1  with the main difference being that of the magnet structure  13   c  mounted inside of the voice coil former  21 . In this embodiment magnetic structure  13   c  preferably uses at least one high-energy magnet  13   d , such as Neodymium or Samarium Cobalt. To better accommodate the magnet structure  13   c , the U-Yoke structure  12   c  is arranged outside of the magnet structure  13   c  and voice coil former  21  and top plate  14   a  is positioned inside of voice coil former  21 . In this configuration the opening  22  in the T-Yoke  12  of the other examples is replaced with a vented opening  22   a  in the U-Yoke  12   c  and magnet structure  13   c . Alternatively, this embodiment  10   h , magnet structure  13   c  may consist of one or more disc magnets without a hole in the center. 
       FIG. 10  shows a cut-away view and  FIG. 10A  a close up view that depicts a ninth example low profile loudspeaker transducer device  10   i . The ninth example  10   i  is essentially the same as the device in  FIG. 1  except that in this embodiment coupler  20   b  has a top cap  23  across the top of voice coil former  21  creating a very broad surface contact area between the coupler  20   b  and diaphragm  18 , increasing the stiffness across the central portion of diaphragm  18 , controlling diaphragm breakup modes and improving the frequency response of transducer  10   i.    
       FIG. 11  shows a close up view that depicts a tenth example low profile loudspeaker transducer  10   j  similar to the device of  FIG. 10  but with coupler  20   c  being a top cup that form fits over the top of voice coil former  21  and attach over a broad surface area of diaphragm  18  increasing structural integrity of diaphragm  18 . 
       FIG. 12  shows a cross sectional view that depicts an eleventh example low profile loudspeaker transducer  10   k  of the same basic structure as that of  FIG. 2 , replacing the convex dome diaphragm  18  of  FIG. 2  with a frustoconical, inverted convex cone structure  18   c  (shown in  FIG. 12A ) with top center opening  28 . Diaphragm  18   c  is connected to coupler  20  and flat dust cap  24   a  is mounted in opening  28  and to one or both of voice coil former  21  and second coupler  20   d  mounted to the inside circumference of voice coil former  21 . The side  18   d  of the cone diaphragm  18   c  may be a straight, or somewhat curved in a convex or concave form. 
       FIG. 13  shows a cross sectional view that depicts a twelfth example low profile loudspeaker transducer  101  of the same basic structure as that of  FIG. 12 , with the flat top dust cap  24   a  of  FIG. 12  replaced by a substantially straight sided concave dust cap  24   b  mounted in opening  28  and to one or both of the voice coil former  21  and diaphragm  18   b  and diaphragm  18   b  attached to coupler  20 . 
       FIG. 14  shows a cross sectional view that depicts a thirteenth example low profile loudspeaker transducer  10   m  of the same basic structure as that of  FIG. 13 , with the concave dust cap  24   b  and diaphragm  18   b  of  FIG. 13  replaced by seamless inverted cone diaphragm which is coupled to voice coil former  21  through coupler  20  and to one or both of the voice coil former  21  and diaphragm  18   b  and diaphragm  18   b  attached to coupler  20 . 
       FIG. 15  shows a cross sectional view that depicts a fourteenth example low profile loudspeaker transducer  10   n  of the same basic structure as that of  FIG. 13 , with the straight sided concave dust cap  24   c  of  FIG. 13  replaced by rounded convex dust cap  24   c  attached to one or both of the voice coil former  21  and diaphragm  18   b . Diaphragm  18   b  is attached to coupler  20  and to voice coil former  21 . 
     In the various embodiments it is generally preferred to attach the diaphragm  18  to coupler  20  but optionally the diaphragm may be attached directly to the voice coil former  21  without coupler  20  or diaphragm  18  may be attached to both voice coil former  21  and coupler  20 . 
       FIG. 16  shows a cross sectional view that depicts a fifteenth example low profile loudspeaker transducer  10   o  of the same basic structure as that of  FIG. 15 , with the rounded convex dust cap  24   c  of  FIG. 15  inverted to a concave form in this example  10   o . Diaphragm  18   b  is shown as attaching to coupler  20  and dust cap  24   d  is attached to diaphragm  18   b  in this example. 
       FIG. 17  shows a cross sectional view that depicts a sixteenth example low profile loudspeaker transducer  10   p  which is similar to the embodiment in  FIG. 12  except the standard coupler  20  of  FIG. 12  is replaced with compliant coupler  29  which is attached to and between top dust cap  24   a  and voice coil former  21 . Dust cap  24   a  is attached to diaphragm  18   b . Compliant coupler  29  can be configured as an open structure with compliant sidewall  30  or can be a closed/sealed structure with the air contained within adding extra stiffness to the compliant coupler  29 . Additionally, resistive losses can be incorporated into the compliant coupler  29 . Compliant coupler  29  can be used as a low pass mechanical filter by progressively decoupling the voice coil former  21  from dust cap  24   a  and diaphragm  18   b , essentially forming a bandpass system. Alternatively, Compliant coupler  29  can be configured as a mechanical resonator with the compliance of the coupler and the moving mass of diaphragm  18   b  forming a resonance that can be used to tune the amplitude response of the high frequencies of loudspeaker transducer  10   p.    
       FIG. 18  shows a cross sectional view that depicts a seventeenth example low profile loudspeaker transducer  10   q  which is the same as the device of  FIG. 2  with the addition of rear suspension  31  mounted below back plate  12   b  and attached to coupling rod  32  protruding through open t-yoke  22  coupling rear suspension  31  to diaphragm  18 , with the rear suspension  31  adding an additional degree of stability to minimize voice coil former  21  rocking or twisting during large excursions of diaphragm  18 . In alternative embodiments a coupling structure, replacing the coupling rod  32 , could be placed outside of the magnet structure with an alternative rear spider that has a larger outside diameter, which may be a particularly useful approach with smaller diameter magnet structures, such as the Neodymium structure shown in  FIG. 9 . With the application of spider suspension  31  spider suspension  17  may be deleted from the transducer or may be used in conjunction with suspension spider  31 . 
     In the various embodiments the diaphragm  18  can be made from a number of materials including aluminum, titanium textile cloth, paper pulp and a wide variety of materials known in the art for loudspeaker transducer materials. 
     In the various embodiments disclosed the invention utilizes the space provided by the protruding dome or inverted cone diaphragm  18  geometry to raise the magnetic structure  13  up into the concave inside cavity of the diaphragm  18  allowing the reduction of the total height of the transducer. Due to the requirement of a short distance between the diaphragm and the motor the spider  17  is configured into the disclosed configuration. The spider  17  design with inner periphery fixed and coupled to the top plate  14  of the motor/chassis and outer periphery attached to the dome diaphragm  18  is an essential element in the inventive transducer. 
     The dome or inverted cone shape diaphragm  18  embodies a characteristic of the invention that the diaphragm structure is preferred to have geometry with height and internal cavity volume. This can embody a dome-like, inverted cone or pyramid-like diaphragm form in terms of exhibiting its maximum height in the center of its geometry at some point over the voice coil former  21 . 
     As it has been mentioned above, the shape of the diaphragm is not limited to the dome shape but any other geometries which deliver enough height between its center portion and the fixation point to the surround to harbor the magnetic motor structure; straight diaphragms (from the surround connection up until the maximum point, conical shape), flat top on the former, inverted cone geometries, and other generally convex forms can be effective. 
     Certain non-continuous surface diaphragm  18  constructions can also provide improved the acoustic performance of the transducer. This can attenuate the modes appearing at the center part of the diaphragm by increasing the stiffness of this area. 
     Different materials can be applied to each part of a two-part diaphragm  18   a  (as shown in  FIG. 3 ) inner disk  24  portion of the diaphragm  18   a  and the outer portion of the diaphragm  18   a  structures. The join between these two pieces can take place through the coupler  20 . The connection between the inner  24  disk and the coupler  20  is desired to be as strong as possible whereas the outer disk  18   a  is attached using soft or damping glue. This configuration works, at high frequencies, as an attenuator of the vibration transmitted to the outer disk  18   a  being useful to smooth peaks caused by a break-up phenomenon and can alternatively create a low pass filter at high frequencies and progressively reducing effective diaphragm diameter with increasing frequency. 
     The coupler  20  can improve the acoustic and mechanical capability of the transducer  10  in that the coupler device  20  increases the stiffness of the center area of the diaphragm  18  radiation surface which has beneficial effects in the frequency response of the driver  10  (extension of the piston radiation area); especially at the high end of its working frequency range where increasing the rigidity of the diaphragm  18  helps to control the amplitude of its vibration modes. 
     Besides increasing the stiffness of the center area of the diaphragm  18  radiation surface the coupler  20  also stiffens the upper end of the voice coil former  21  neck, ensuring a rigid and reliable connection to diaphragm  18  improving frequency response and creating stronger connections for a greater mechanical power handling. 
     The coupler device  20  can be configured such that it has multiple connection points from the voice coil former  21  to the diaphragm  18  balancing the force provided by the voice coil  19 . This configuration also further contributes to increased control of the vibration modes of the diaphragm  18 . 
     Depending on the material the rigid coupler  20  or compliant coupler  30  is made of, the damping of the connection system can be modified and adapted to desired characteristics. Accordingly, the compliant coupler  30  of as one example is shown in  FIG. 30 , can operate as a low pass filter, damper or resonant system. 
     Additionally, a ring with an L-shaped cross section, or a small cone shaped piece to join the voice coil former  21  to the diaphragm  18  surface, enables the use of a continuous diaphragm  18  surface and avoids the structurally weaker butt joint that would be normally be formed by connecting only the voice coil former  21  directly to the diaphragm  18  without the coupler  20 . 
     One of the possible diaphragm geometries that meets the requirements aforementioned also includes a radiation surface shaped in a way that exhibits a first dome-like geometry ( 18 ) which harbors the magnetic motor structure of the speaker and whose body edge is folded upwards forming an outer cone-like second geometry ( 18   e ) ( FIG. 19 ). The second geometry body meets the surround ( 16 ) at the end of its structure. The outer cone could be made of the same piece as the central dome, or be a second separate piece attached or coupled to the first geometry, with its inner diameter virtually bigger than the magnetic motor structure housed by the central dome. Underneath this double-geometry diaphragm structure and at its fold or groove point or section, or nearby (where the two geometries “meet” each other), the outer periphery of the spider suspension  17  is connected or coupled (unlike the rest of the embodiments, the spider element is not attached at, or nearby, the end of the radiation surface body). This folded dome helps to cope with the disadvantage of having dynamic coil loudspeakers with relatively big and low profile dome diaphragms whose stiffness is similar to that presented by flat geometries. 
     The groove or fold area can be treated to improve the behavior of the loudspeaker at the break-up frequency region by adding either a stiffening or damping element, like specific type/s of glue/s, on the groove surface ( 34 ). With the same objective (controlling the smoothness of the sound pressure level curve), stiffening or damping elements, like glue or rubber mass, can be placed/attached on the back side of the second geometry ( 35 ); their amount and position depends on the desired effect on the driver&#39;s performance; this will help to break the vibration modes of the diaphragm at certain frequencies and consequently distributing their energy over a wider area of the audible spectrum. 
     A plastic ring or brushing ( 33 ) is disposed as a coupling element between the magnetic motor structure and the basket. This element provides a fitted wrapping of the motor strongly keeping it in place and connecting it to the basket. 
     Manufacturing methods can center the voice coil former  21  in the gap by utilizing a fixture, which is removed from the front face of the transducer once the spider  17  and the cone diaphragm  18  have been properly glued to the basket and the former. This method takes advantage of the hole  28  in the center of a conical cone diaphragm  18   c  (shown in  FIG. 12A ) geometry to access to the fixture. The assembly of a dust cup  24   a  over or on the voice coil former  21 , closing this hole  28 , completes the process. 
     As an alternative preferred construction method, the fixture which positions the voice coil in its predetermined placement must be removed from the back side of the transducer as the dome diaphragm does not present any aperture from which accessing to the centering device. In order to do that, the T-yoke  12  comprises two pieces: a regular T-yoke  12  and an extra back plate  11   a  (shown in  FIG. 1 ). This extra back plate  11   a  is located in between the magnet structure  13  and the bottom, or back plate  12   a , of the regular T-yoke  12 . Both, the basket frame  11  and the motor (which comprises only the magnet  13  and the top plate  14  in this case) rest on the back plate  12   b  allowing the T-yoke  12  to be easily unattached from the transducer  10  structure. This action does not compromise the effectiveness of the transducer  10  assembly or production process and takes place after the successful assemblage of the diaphragm  18  and spider  17  in the system. Removing the T-yoke  12  gives access to the fixture, which was placed on the pole piece  12   a . Once the fixture is taken apart, the T-yoke  12  is positioned back and glued/screwed to the back plate  12   b . A proposed assembly method is described step-by-step as follows:
         1. Assemble the back plate  12   b  and the T-yoke  12  (No glue is used).   2. Attach the magnet  13 , top plate  14  and aluminum ring (consecutively) to the back plate.   3. Attach together the basket frame  11  and the back plate  12   b  using glue, screws or both.   4. Fix the inner periphery of the spider  17  on the aluminum ring.   5. Attach the coupler  20  (ledge-like piece) to the former using a flat surface to align the top parts of these two elements (if the coupler is made of two parts the process does not vary, the second part of the coupler  20  which looks like a dust cup going on the former will be attached after the first element).   6. Put the fixture on the pole piece  12   a  to set the voice coil  19  in its optimal placement in the motor gap.   7. Between top plate  14  and pole piece  12   a , fit the voice coil former  19  in the fixture.   8. Attach the dome diaphragm  18  to the voice coil former  21  by means of the coupler  20 .   9. Glue the lead wires underneath the dome to the surround.   10. Fix the dome diaphragm  18  to the spider  17  and the basket  11 .   11. Remove the T-yoke  12  from the structure and the fixture from the pole piece  12   a.      12. Place the T-yoke  12  back to its position and fix it there.       

     Similar to the ferrite magnet version as shown in  FIG. 1 , this method applied to the Neodymium magnet version (illustrated in  FIG. 9 ) implies removing the fixture from the backside of the transducer  10  in the last step of the assembly. The basket/frame  11  design of the invention facilitates the extraction of the motor (U-yoke  12   c , neo magnet  13  and top plate  14   a ) allowing access to the fixture. None of the moving parts are directly attached to the magnetic motor but instead, to the basket. There is no aluminum ring in this version. 
     It is evident that those skilled in the art may now make numerous uses of and departures from the specific apparatus and techniques disclosed herein without departing from the inventive concepts. Consequently, the invention is to be construed as embracing each and every novel feature and novel combination of features disclosed herein, and the examples of the present invention disclosed herein are intended to be illustrative, but not limiting, of the scope of the invention 
     Finally, it should be noted that the language used in the specification has been principally selected for readability and instructional purposes, and may not have been selected to delineate or circumscribe the inventive subject matter. Accordingly, the disclosure of the present invention is intended to be illustrative, but not limiting, of the scope of the invention.