WO1993001691A1

WO1993001691A1 - Electrolytic loudspeaker assembly

Info

Publication number: WO1993001691A1
Application number: PCT/US1991/004908
Authority: WO
Inventors: Michael L. Driver
Original assignee: Driver Michael L
Priority date: 1991-07-11
Filing date: 1991-07-11
Publication date: 1993-01-21

Abstract

An electrolytic loudspeaker assembly (10) designed to reproduce a broad band of audio signals and that consists of a thin, non-magnetic capacitive transducer (12) and a transducer driver unit (60). The transducer (12) consists of a vibratory center section (16) having on each surface a respective front section (26) and back section (32). Each section has an area that is less than 75 percent of the center section area and the entire compound diaphragm is held captive by a frame assembly (40). After the capacitive transducer (12) is completed, it is subjected to a one-time polarization and discharge cycle that provides the transducer with a permanent residual charge. The transducer (12) is driven and controlled by the transducer driver unit (60). The unit couples the audio signal to the transducer, supplies a regulated bias voltage and includes a dielectric drain circuit that maintains the proper ratio between the bias voltage and audio signal to achieve optimum performance.

Description

ELECTROLYTIC LOUDSPEAKER ASSEMBLY

TECHNICAL FIELD

The invention pertains to the general field of loudspeakers and more particularly to an electrolytic loudspeaker assembly consisting of a polarized, non-magnetic, capacitive transducer that is driven by an electronics transducer driver circuit.

BACKGROUND ART since the advent of "high fidelity" audio systems, engineers have strived to develop loudspeakers that were relatively free from distortion and with a frequency response that would allow concert hall music to be closely reproduced. Loudspeakers are broadly categorized as being either magnetic, moving coil speakers or non-magnetic, electrostatic speakers/ transducers. The instant invention discloses an electrolytic speaker which is more closely related to the electrostatic types. Therefore, the reminder of the discussion pertains to only electrostatic speakers.

Most prior art electrostatic speakers generally consist of a center flexible membrane or diaphragm having on each side a fixed electrode in the form of a grid of wires. The wires are spaced apart so as to enable sound waves generated by the movement of the flexible membrane to be emitted. The wires are sheathed in a dielectric insulation material and the flexible membrane has a coating of a highly resistive material. The membrane is further suspended within an open latticed frame between the electrode wires so that when operated, relatively small segments of the diaphragm are enabled to vibrate under the influence of the electrostatic fields acting upon the diaphragm.

A search of the prior art did not disclose any patents that read directly on the claims of the instant invention however, the following U.S. patents were considered related:

PATENT NO. INVENTOR ISSUED

4,160,882 Driver 10 July 1979

3,942,029 Kawakami et al 2 March 1976 3,705,312 Sessler et al 5 December 1972 3,345,469 Rod 3 October 1967

The Driver patent discloses an electrostatic transducer that has applicability as a loudspeaker.

The transducer consists of two parallel diaphragms each consisting of two plastic sheets, having different charge carrying characteristics, that are sandwiched between an electrically conductive layer. The two diaphragms are separated by a centrally located perforated electrically conductive sheet and a foraminus dielectric material sandwiched between the conductive sheet and each diaphragm. The diaphragm's two electrically conductive layers are connected across the secondary winding of an audio transformer and the centered electrically conductive sheet is connected to the center tap of the transformer. Thus, when the transformer is applied an audio signal the two diaphragms are driven in a push-pull relation to reproduce the audio. Note that the inventor of this patent is also the inventor of the instant application.

The Kawakami et al patent discloses an electrostatic transducer that can be utilized in either a speaker or microphone. The transducer consists of a vibrating plate or electret diaphragm having a monocharge of positive or negative potential on its surface. The electret diaphragm is made of a thin polymer film that is bonded to a support so that uniform tension exists. A pair of electrically conductive electrodes are brought in contact with opposite sides of the polymer films, and an electrostatic shield, such as a mesh, covers the surface of the two electrodes. A d-c voltage is time-applied across the electrodes to allow, the electret to heat to its curie temperature of 120° C. The electret is subsequently cooled to produce a quasi permanent state of electric polarization.

The sessler patent discloses a method for preparing a thin-film electret. The method includes placing a thin polymer film between, two electrodes together with a dielectric plate. A voltage of about 30 keV is then applied across the resulting sandwich of elements for about one minute at room temperature and at atmospheric pressure. The method produces charge-densities which are greater by a factor of three than those previously reported.

The Rod patent discloses a loudspeaker that operates on electrostatic principles. The speaker consists of a centrally located movable diaphragm which is coated on both sides with a thin, flexible electrically conductive layer. On each side of the diaphragm is located at least one hermetically sealed Plastic dielectric sheet. When air or other gas is trapped between the sheets and the diaphragm, a buffer zone is created. To each outermost dielectric sheet is attached an electrode and to the centered conductive diaphragm is likewise attached an electrode. The two buffer electrodes are connected across the secondary winding of a step-up transformer and the diaphragm electrode is connected through a d-c voltage source to the centertap of the transformer. The transformer's primary winding is connected to the diaphragm driving signal that is derived from the signal input from a conventional low-impedance amplifier. The above described electrostatic transducers, although being superior in many respects over the moving-coil type, have received poor industry/consumer acceptance. This poor acceptance is due in part to the undue mechanical complexity of some designs, low acoustic output, the requirement for a comparatively large radiating area and a dependence upon the application of a relatively high d-c polarizing bias voltage between the flexible diaphragm and the wire grid electrodes. For example, a typical full range push-pull electrostatic speaker requires a bias voltage of 3500 volts d-c and a driving amplifier with a power capacity of from 60 to 100 watts. Additionally, the prior art electrostatic speakers are only able to reproduce adequately from the mid-range and higher audible frequencies. Therefore, a bass speaker is commonly connected to reproduce the bass frequencies.

To overcome some of the above defects, transducers utilizing electrets as the diaphragm have been employed. The electret diaphragm was thought to be permanently polarized or charged and therefore not requiring a separate polarizing d-c voltage. However, these electrets have been found to be unsatisfactory for application as loudspeakers because they decay, at least to a first approximation, according to an equation of the form dp/dt = α P because the dis-alignment of the partially oriented dipoles is a random process.

DISCLOSURE OF THE INVENTION

The disclosed electrolytic loudspeaker assembly is designed to reproduce a broad band of the audible spectrum by utilizing a relatively flat, non-magnetic and non-ferrous structure. Because of its flat structure, the loudspeaker can be placed or mounted in places that are unsuitable for conventional loudspeakers. The flattened design also allows the structure to be bent or curved which further extends its mounting capabilities. Additionally, because of its inherent low weight, the loudspeaker is ideal for use in weight-critical situations such as in aircraft and spacecraft. Another physical aspect of some importance is that if the structure is pierced the audio output will continue. This feature is especially important when the loudspeaker assembly is used in military compounds, vehicles, aircraft and spacecraft.

The electrolytic loudspeaker consists of two major elements: a polarized capacitive transducer and a transducer driver unit. In electrical terms, the capacitive transducer resembles two back-to-back electrolytic capacitors. The center plates are attached to form a center section that is connected to a single center electrode and the two outer plates are connected respectively to a front and back electrode.

In the actual design configuration, The electrolytic loudspeaker assembly consists of a polarized compound diaphragm further consisting of a center section having attached to each surface respectively, a front section and a back section and a frame assembly that holds the entire compound diaphragm. The center section, which constitutes the primary vibratory element, includes a first and second metallized film that after attachment to the frame are heat shrunk to provide the proper tension. The two films are in intimate contact, separated only by a thin coating of a petroleum gel that serves to provide proper damping. The front and back sections are each comprised of a grided plastic spacer each having in intimate contact on their outer surface an aluminum perforated plate. Each of the front and back sections have an area that is less than 75 percent of the center section area and are intimately attached to the center section with the metal plates facing outwardly. After the capacitive transducer is structurally completed it is subjected to a one-time polarization and discharge cycle to instill the transducer with a permanent residual charge that ranges from 200 to 500 volts ESU. The compound diaphragm is driven and controlled by the transducer driver unit. This unit couples the incoming audio signal to the front and back sections via the front and back electrodes connected to the front and back sections, supplies a regulated bias voltage to the center electrode of the center section and includes a dielectric drain circuit that maintains the ratio of the bias voltage and audio signal at the proper ratio to achieve optimum performance.

In view of the above disclosure, it is the primary object of the invention to provide an electrolytic loudspeaker assembly that with a small physical volume reproduces the audio signal over a wide frequency range. It is also an object of the invention to provide an electrolytic loudspeaker assembly that:

o features a built-in bias enhancement and dielectric drain,

o is cost effective from both an end user and manufactures point of view, o is highly reliable and easily maintained, o does not require the high signal and bias voltages needed to operate electrostatic loudspeakers and,

o can be mounted in various positions and locations that are not possible with current magnetic moving-coil speakers and electrostatic speakers.

These and other objects and advantages of the present invention will become apparent from the subsequent detailed description of the preferred embodiment and the claims taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGURE 1 is an exploded view of the electrolytic loudspeaker assembly showing the attachment of the capacitive transducer to the transducer drive unit which is connected to an audio source.

FIGURE 2 is a sectional view of the capacitive transducer.

FIGURE 3 is a front plane view of the first or second plastic spacer. FIGURE 4 is a front plane view of the first or second metal plate.

FIGURE 5 is a schematic diagram of the transducer driver unit.

BEST MODE FOR CARRYING OUT THE INVENTION

The best mode for carrying out the invention is presented in terms of a preferred embodiment that is packaged in a thin, easily mounted structure that is designed to reproduce audio signals over a wide frequency range.

In its basic configuration, the electrolytic loudspeaker assembly 10 as shown in FIGURES 1-5 is comprised of two major elements: a capacitive transducer 12 and a transducer driver unit 60. The transducer 12 is further comprised of a polarized compound diaphragm 14 consisting of a center section 16, a front section 26, a back section 32 and a frame assembly 40.

The center section 16 consists of four elements: a first metallized film 18 having a metallized surface 18a that faces inwardly, a thin flexible barrier 20 that is sized to cover the metallized surface 18a, a second metallized film 22 having a metallized surface 22a that faces inwardly and that is sized to cover and be in intimate contact with the flexible barrier 20, and a center electrode 44 that is attached to one end of the composite center section 16.

The front section 26 consists of a first plastic spacer 28 having a grid pattern 28a as shown in FIGURE 3. The spacer has an area that is less than the area of the center section 16 and is in intimate contact with the non metallic surface of the first metallized film 18. In intimate contact with the opposite surface of the spacer 28 is a first metal plate 30. This plate has a multiplicity of perforations 30a as shown in FIGURE 4, is sized to cover the spacer 28 and has attached to one of its ends a front electrode 46.

The back section 32 is similarly constructed and sized as described above for the first section 26. The back section as shown in FIGURE 2 consists of a second plastic spacer 34 having a grid pattern 34a, a second metal plate 36 having perforations 36a and a back electrode 48.

The frame assembly 40 as shown in FIGURES 1 and 2 provides the means by which the compound diaphragm 14 is held in a suspended configuration.

The transducer driver unit 60, which is described in detail infra, has the means to interface with the compound diaphragm, to supply a bias voltage that is applied to the center electrode 44, to provide a dielectric drain and to produce an alternating signal that is analogous to the audio signal. The alternating signal is applied across the front and back electrodes 46,48 to allow the polarized compound transducer 12 to be driven in a push-pull relation.

in its preferred embodiment, the first and second metallized films 18,22 are made by evaporating or depositing a thin metal layer, such as aluminum, onto a thin polymer material such as polyethylene terephthalate (PET). The metallized films, which are also known by the tradename MYLAR, are heat shrinkable. Thus, after each film is attached to the frame assembly 40 by an adhesive it is heated so that it is stretched taut allowing the films to oscillate back and forth in the direction of the arrows 38 as shown in FIGURE 2. The heating may be accomplished by a heating means that includes a heat gun or other heat sources.

As best shown in FIGURES 1 and 2, the two films

18,22 are separated by a thin flexible barrier 20 that may consist of a thin rubber sheet but preferably consists of a petroleum gel such as known commercially by its tradename VASELINE. After a thin layer of the gel 20 is spread evenly over the metallized surface 18a, the metallized surface 22a of the second film 22 is placed over the gel to form the center section. The gel functions as a non-drying adhesive and serves to dampen and maintain the structural integrity of the center section 16. To operate within its design parameters, the center section may vary in thickness from 0.001 to 0.03 inches (0.025 to 0.762 mm).

The front and back section 26,32 consist of the first and second plastic spacers 28,34 as shown in FIGURE 3 and the first and second metal plates 30,36 as shown in FIGURE 4. In the preferred embodiment, the plastic spacers have an area, as measured from its width and length that is less than 75 percent of the area of the center section 16. The spacers may have a thickness between 0.001 to 0.009 inches (0.025 to 0.229 mm), can be made of any lightweight non-conductive material and have a grid pattern to create individual areas for vibration. The grid pattern can take any form. However, a grid pattern consisting of thin angular sections 28a interposed within a perimeter border section 28b as shown in FIGURE 3, was found to be very satisfactory.

The metal plates 30,36 in the preferred embodiment are dimensioned to allow the plates to be attached, by an attachment means such as an adhesive, directly over and in intimate contact with the outer surface of the respective plastic spacers 28,34. The plates are preferably made of aluminum having a thickness of between 18 to 26 gauge and have a perforation pattern, In the preferred embodiment the perforations consist of a multiplicity of ordered first bores 30a and second bores 30b where the second bores have a larger diameter than the first bores as shown in FIGURE 4.

The compound diaphragm 14 is designed to be suspended within a frame assembly 40 as shown in FIGURES 1 and 2. The frame assembly 40 in the preferred embodiment consists of two sections, a front section 40a and a back section 40b. Attached, by an adhesive to the inward side of the frame's front section 40a is the outward edges of the metallized surface 18a of the first metallized film 18. Likewise, the outward edges of the metallized surface 22a of the second metallized film 22 are attached to the inward side of the frame's back section 40b. After the metallized films 18,22 are attached, they are heat shrunk to provide the proper tension and the two inward frame sections are brought together in alignment and attached by an attachment means 50. The attachment means 50 may consist of a tape that is folded over the edges of the perimeter of the frame assembly 40 or any other type of clamping structure. The petroleum gel 20 holding the two metallized films 18,22 also aids in maintaining the two frame sections together adding to the structural integrity of the capacitive transducer 12.

After the capacitive transducer 12 is structurally completed it is subjected a one-time polarization and discharge cycle to provide the transducer with a permanent residual charge. The polarization and discharging cycle is well known in the art and therefore is not described in detail. However, for reference the basic steps required are listed below:

1. Short the capacitive transducer's front and back electrodes 46, 48 together and connect them to the positive terminal of a 0-5000 volt d-c power supply likewise, connect the center electrode 44 to the negative terminal of the power supply,

2. Start the power supply at o-volts and step-up the voltage in 100 volt increments; pausing at each increment for 20 ± 5 seconds to allow time for polarization without the occurrence of a Paschen avalanche or electric breakdown, continue until the voltage reaches a level of slightly over 2200 volts at which time the power supply is shut off.

3. Allow the capacitive transducer 12 to discharge through a connected meter. After discharge, connect all leads together to allow the now polarized and charged capacitive transducer to be safely handled.

The resulting residual charge may range between 200 and 500 volts ESU. With the enhancement of this residual charge, by the transducer driver unit 60, the bias on the vibrating diaphragm is maintained at five times the magnitude of the incoming audio signal. A detailed description of the driver unit 60 and the bias enhancement follows.

The second major element of the electrolytic loudspeaker assembly 10 is the transducer driver unit

60. This unit as shown in FIGURES 1 and 5, is preferably designed to directly interface with the capacitive transducer 12 by a combination of an attachment structure 76 and the output connector 74 which accepts the transducers center electrode 40, front electrode 46 and back electrode 48. In lieu of the connector, the electrode leads may be directly soldered to the respective leads on the driver unit 60.

The unit 60 functions to couple the incoming audio signal from the audio source 80 to the front and back sections of the capacitive transducer via the front or back electrodes 46,48; supplies a regulated bias voltage to the transducer's center section via the center electrode 44 and provides a dielectric drain that allows the transducer to operate within its design parameters. To provide the above functions, the driver 60 is comprised of four major elements: an input circuit 62, a full-wave tripler circuit 64, a bias regulator/dielectric drain circuit 66 and a current limiting and d-c smoothing resistor 68.

The relatively high impedance of the capacitive transducer 12 dictates that it be driven by a transformer. Therefore, the input circuit 62 consists of an impedance matching transformer 62a having a secondary to primary turns ratio of 100:1. The transformer's primary winding 62b is connected through input connector 72 to the audio signal which is derived from the output of an audio source 80 such as a radio receiver as shown in FIGURE 1. The transformer's multiple secondary winding 62c consists of four windings labeled 3-4 4-5, 5-6 and 6-7 as shown in FIGURE 5. The audio winding taps 4 and 6 supply the analogous audio signal through an output connector 74 to the front and back electrodes 46,48. The bias windings 3-7 are connected to the full-wave tripler circuit 64.

The full-wave tripler circuit multiplies the a-c input voltage by a factor of three. The stepped-up voltage is then rectified to produce a d-c bias voltage that is applied from the junction of diode 64c and capacitor 64f. Typically, the input audio signal from the audio source 80 is 1 volt a-c. The transformer 62a steps this voltage up to 100 volts a-c which is then tripled and rectified by the circuit 64 to produce a bias voltage of 300 volt d-c. The bias voltage is applied to the transducer's center electrode 44 via the output connector 74 and a 60 megohm bias regulating resistor 68. The magnitude of the applied bias voltage is dependent upon the level of the incoming audio signal. However, in all cases, the bias voltage enhances the residual charge of the polarized compound diaphragm preset during the transducer's polarization and discharging cycle described supra. With this enhancement, the driver transducer circuit 40 is able to maintain a bias on the vibrating transducer, which at all times, is regulated to maintain a level that is at least five times the magnitude of the received audio signal. The combination of the input signal and bias voltage allows the diaphragm to operate under the basic laws of magnetism which causes the diaphragm to vibrate in a controlled manner.

As previously described, the first and second plastic spacers 28,34 are in intimate contact with the respective first and second metal plates 30,36 which forms an electrical junction JA. Also, the intrinsic contact between the plastic layer and the metallized surface 18a, 22a of the first and second metallized films 18,22 form an electrical junction JB. Both these junctions as shown in FIGURE 2, function as high impedance diodes. When the audio signal is received, most of the electrons function as magnets to cause the polarized compound diaphragm 14 to vibrate at a frequency that corresponds to the frequency of the audio signal. The surplus electrons that do not contribute to the vibrating action are simply rectified at the JA and JB junctions. If these rectified electrons are left unattended they will accumulate over time and eventually cause an exponential decay in the audio output. Additionally, the surplus electrons may begin sparking, and in some cases will perforate the thin plastic films of the center section 16.

To solve this excess electron problem, the combination of three elements are used: a high ohmic value drain resistor 62d, the bias regulating resistor 68 and the bias regulator/dielectric drain circuit 66 which further consists of a dielectric dissipating/regulating section 66a, a secondary regulating section 66b and a primary regulating section 66c.

As shown in FIGURE 5, the drain resistor 62d is attached between the center tap 5 of the transformer 62a and the junction of diode 64a and capacitor 64e which corresponds to the input of the full-wave tripler circuit 64. Note that resistor 62d is the equivalent of a grid leak resistor Rg as designated in vacuum tube technology. The circuit 66 is connected across the input and the output of the tripler circuit 64; and the bias regulating resistor 68 is located between the output of the circuit 64 and the center electrode 44.

The accumulated electrons from the two JB junctions, are drained through the secondary winding 62c of the transformer 62a and drain resistor 62d. The electron drain and bias regulation for junctions JA is provided via electrode 44, resistor 68 and circuit 66 where the electrons are primarily dissipated as heat energy through mechanical work and vibration and by the combination of resistor 66d, neon lamp 66e and capacitor 66f. Any remaining electrons are filtered by capacitors 66i, 66j and 66k in the section 66c, and by resistor 66g and capacitor 66h in the section 48b and ultimately regulated by the section 66a. There is no apparent electron movement through the capacitive transducer 12 itself. Therefore, capacitor 66h discharges through capacitors 66i, 66j and 66k to maintain the 5:1 ratio between the bias voltage and audio signal.

The suspension and mounting scheme of the center section 16 and the front and back sections 26,32 of the compound diaphragm 14 provide a substantial mechanical advantage that allows the capacitive transducer 12 to operate at an extended frequency range.

In this mounting scheme, the front and back sections 26,32 contribute to the degree of oscillating distance that the center section 16 can travel but the width and grid design of the first and second spacers

28,34 and the first and second metal plates 30,36 divides the center section 16 into smaller segments. The frequency response characteristics of these smaller segments become a function of the smaller section mass and length. Note that in all cases, the tension of the compound diaphragm 14 remains constant, If the area of each first and second metal plates 30,36 does not exceed 75 percent of the area of the diaphragm's center section 16, the acoustic output over the total area of the center section will contain usable audio information. This information will be responsive down to the fundamental mechanical resonant frequency of the center section due to the strength of the driving forces.

A calculation performed on the capacitive transducer 12 has determined that electrostatic units (ESU) converted into magnetic equivalents provide approximately 18000 gauss of flux density. This is the equivalent of a magnetic assembly weighing approximately 10 lbs (4.5 Kg).

The design of the capacitive transducer 12 allows the design of a loudspeaker to be related to the laws of physics, which govern the vibration of strings and columns of air by application of the following formula:

where: F = Fundamental mechanical resonant frequency

L = Length

T = constant Tension

M = Mass

The primary design configuration of the capacitive transducer 12 provides wide performance characteristics. However, from the above formula, it can be seen that by varying the mass and length, a capacitive transducer that operates, on a different section of the audible spectrum can be designed. in a practical sense, the operating parameters of the transducer can be tailored by design in about the same manner as one would build and tune a piano.

Once a physical size and shape for a capacitive transducer 12 has been determined, whether it be for a loudspeaker or earphones, the front and back sections 26,32 are sized to cover an area that is less than 75 percent of the area of the center section 16. The capacitance of the capacitive transducer 12 is then measured or calculated. The capacitive reactance is calculated to match the center of the band of frequencies the transducer is to reproduce. Once the capacitive reactance is expressed in ohms, the input transformer 62a can be wound to match the required band pass. No additional design changes are necessary in the remaining components of the transducer driver circuit 60.

while the invention has been described in complete detail and pictorial ly shown in the accompanying drawings, it is not to be limited to such details, since many changes and modifications may be made in the invention without departing from the spirit and the scope thereof. For example, a curved capacitive transducer 12 can be easily designed and manufactured. Hence, it is described to cover any and all modifications and forms which may come within the language and scope of the claims.

Claims

CLA IMS

1. An electrolytic loudspeaker assembly comprising:

A. A capacitive transducer having a polarized compound diaphragm further comprised of: a. a center section comprising:

(1) a first metallized film having a metallized surface that faces inwardly,

(2) a thin flexible barrier sized to cover the metallized surface of said first metallized film,

(3) a second metallized film having a metallized surface that faces inwardly and that is sized to cover and be in intimate contact with the opposite surface of said flexible barrier,

(4) a center electrode attached to one end of said center section,

b. a front section comprising:

(1) a first plastic spacer having a grid pattern and an area that is less than the area of said center section and where said spacer is in intimate contact with the non-metallic surface of said first metallized film,

(2) a first metal plate having a multiplicity of perforations, and that is sized to cover and be in intimate contact with said first plastic spacer, (3) a front electrode attached to one end of said first metal plate, c. a back section comprising:

(1) a second plastic spacer having a grid pattern and an area that is less than the area of said center section and where said spacer is in intimate contact with the non-metallic surface of said second metallized film,

(2) a second metal plate having a multiplicity of perforations, and that is sized to cover and be in intimate contact with said second plastic spacer,

(3) a back electrode attached to one end of said second metal plate, d. a frame assembly having the means to suspend said compound diaphragm, and B. a transducer driver unit having the means to:

a. interface with said polarized compound diaphragm,

b. supply a bias voltage to the center electrode, and

c. provide an alternating signal, analogous to the audio signal, that is applied across said front and back electrodes to allow said polarized compound diaphragm to be driven in a push-pull relation.

2. The assembly as specified in claim 1 wherein said metallized films are made by evaporating or depositing a thin metal layer onto a thin polymer material.

3. The assembly as specified in claim 2 wherein said polymer material consists of polyethylene terephthalat (PET).

4. The assembly as specified in claim 3 wherein said polymer material is heat shrinkable which allows the material attached to said frame assembly to be stretched taut after the material is heated by a heating means.

5. The assembly as specified in claim 1 wherein said flexible barrier is comprised of a thin layer of petroleum gel spread evenly over the metallic surface of said first metallized film after which, the metallic surface of said second metallized film is placed over the gel to form said center section.

6. The assembly as specified in claim 1 wherein said flexible barrier is comprised of a thin rubber sheet.

7. The assembly as specified in claim 1 wherein said plastic spacers have a grid pattern consisting of thin angular sections interposed within a perimeter border section.

8. The assembly as specified in claim 7 wherein the area of said plastic spacers as measured from its width and length is less than 75 percent of the area of said center section.

9. The assembly as specified in claim 8 wherein said plastic spacers have a thickness between 0.001 to 0.009 inches (0.025 to 0.229 mm).

10. The assembly as specified in claim 9 wherein said metal plates are dimensioned to allow said plates to be attached by an attachment means directly over and in intimate contact with outer surface of the respective said plastic spacers.

11. The assembly as specified in claim 10 wherein said metal plates are made of aluminum and have a perforation pattern consisting of ordered first bores and second bores.

12. The assembly as specified in claim 11 wherein said second bores have a larger diameter than said first bores.

13. The assembly as specified in claim 1 wherein said frame assembly comprises:

a) a front section having attached to its inward side the outward edges of the metallized surface of said first metallized film, and

b) a back section having attached to its inward side the outward edges of the metallized surface of said second metallized film, where the two inward frame sections are brought together in alignment and attached by an attachment means to thus form said compound diaphragm.

14. The assembly as specified in claim 13 wherein after said metallized films are attached to the respective sections of said frame assembly a heat is applied over said metallized films to cause said films to become taut.

15. The assembly as specif ied in claim 1 where i n said capacit i ve transducer is subjected to a one-time polarization and discharge cycle to provide said transducer with a permanent residual charge.

16. The assembly as specified in claim 15 wherein said residual charge ranges between 200 to 500 volts

ESU.

17. The assembly as specified in claim 1 wherein said means to that allows said transducer driver circuit to interface with said capacitive transducer is comprised of a combination attachment structure and the output connector.

18. The assembly as specified in claim 1 wherein said transducer driver comprises:

a) an input circuit consisting of an input transformer having an input winding connected to the incoming audio signal and multiple secondary windings consisting of an audio winding that supplies the analogous audio signal to the front and back electrodes located respectively in said first and back metal plates and also having a bias winding and a center tap connected to a drain resistor, b) a full-wave tripler circuit having its input connected to said drain resistor and also connected across the bias winding of said transformer, where said tripler circuit produces a d-c bias voltage that is applied through a bias regulating resistor to the center electrode located on the center section of said compound diaphragm, and c) a bias regulator/dielectric drain circuit that is connected across the input and. output of said tripler circuit and that functions in combination with said drain resistor and said bias regulating resistor to maintain a regulated and constant bias voltage applied to the center electrode.

19. The assembly as specified in claim 18 wherein said input transformer has a secondary to primary turns ratio of 100: 1.

20. The assembly as specified in claim 19 wherein the magnitude of the bias voltage, which is dependent upon the level of the incoming audio signal, enhances the residual charge of said polarized transducer preset during an initial polarization and discharge cycle.

21. The assembly as specified in claim 20 where the bias voltage is at all times five times the magnitude of the received audio signal.

22. The assembly as specified in claim 18 wherein said bias regulator/dielectric drain circuit comprises:

a) a secondary regulating section having an input and an output,

b) a dielectric dissipating/regulating section having one side connected to the input of said tripler circuit and the output connected to the input of said secondary regulating section, and

c) a primary regulating section having one end connected to the output of said secondary regulating section and its other end connected to the output of said tripler circuit, wherein said bias regulator/dialectric drain circuit further functions to drain any surplus electrons that have accumulated at the JA junctions located between said first and second plastic spacers and the respective first and second metal plates and at a JB junction located at the intrinsic contact between the plastic layer and the metallized section of the first and second metallized foils.

23. The assembly as specified in claim 18 wherein said capacitive transducer can be designed to operate at selected areas of the audible spectrum by varying the length and mass of said center section and the application of the following equation:

where: F = Fundamental mechanical resonant frequency

L = Length

T = Constant Tension

M = Mass

where when the physical size and shape of said center section has been determined the following steps are followed:

a) size said front and back sections to have an area that is less than 75 percent of the area of said center section,

b) calculate the capacitive reactance of said capacitive transducer to match the center of the band of frequencies the transducer is to reproduce, and

c) wind said input transformer to match the required band pass.

24. An electrolytic loudspeaker assembly comprising:

(1) a first metallized film that is heat shrinkable and has a metallized surface that faces inwardly,

(2) a thin layer of petroleum gel spread evenly over the metallized surface of said first metallized film,

(3) a second metallized film also being heat shrinkable and having a metallized surface that faces inwardly and sized to cover and be in intimate contact with said layer of petroleum gel covering said first metallized film,

(4) a center electrode attached to the lower end of said center section, b. a front section comprising:

(1) a first plastic spacer having a thickness between 0.001 to 0.009 inches (0.025 to 0.229 mm), a grid pattern having a plurality of thin angular sections interposed within a perimeter border section, an area that is less than 75 percent of the area of said center section and where said spacer is in intimate contact with the non-metallic surface of said first metallized film, (2) a first metal plate having a multiplicity of perforations consisting of ordered first bores and larger second bores and sized to cover and be in intimate contact with said first plastic spacer,

(3) a front electrode attached to the lower end of said first metal plate,

c. a back section comprising:

(1) a second plastic spacer having a similar thickness, grid pattern and area as that of said first plastic spacer and that is in intimate contact with the non-metallic surface of said second metallized film,

(2) a second metal plate having a multiplicity of perforations similar to those of said first metal plate and that is sized to cover and be in intimate contact with said second plastic spacer,

(3) a back electrode attached to the lower end of said second metal

Plate,

d. a frame assembly comprising

(1) a front section having attached to its inward side the outward edges of the metallized surface of said first metallized film, where after attachment heat is applied to said film to allow said film to shrink and be stretched taut, (2) a back section having attached to its inward side the outward edges of the metallized surface of said second metallized film which is also heat shrunk to provide a taut fit and where the two inward frame sections are brought together in alignment and attached by an attachment means to thus form said compound diaphragm, whereupon said compound diaphragm is subjected to a one-time polarization and discharge cycle to provide said polarized compound diaphragm with a permanent residual charge that ranges between 200 to 500 volts ESU, and,

B. a transducer driver unit having the means to:

a. interface with said polarized compound diaphragm,

b. supply and regulate a bias voltage that is applied to the center electrode, and c. provide an alternating signal, analogous to the audio signal, that is applied across said front and back electrodes to allow said polarized compound diaphragm to be driven in a push-pull relation.