US2035108A

US2035108A - Sound distributing and amplifying device

Info

Publication number: US2035108A
Application number: US694030A
Authority: US
Inventors: Weil Maximilian
Original assignee: Individual
Current assignee: Individual
Priority date: 1933-10-18
Filing date: 1933-10-18
Publication date: 1936-03-24
Anticipated expiration: 1953-03-24
Also published as: GB444708A

Description

March 24, 1936. M, WEIL 2,035,108

SOUND DISTRBUTING AND AMPLIFYING DEVICE Original Filed OCL. 18, 1933 0&9 BYYEYZ IM] VQI ATTORN EY Patented Mar. 24, 1936 UNITED STATES PATENT OFFICE SOUND DISTRIBUTING AND AMPLIFYING DEVICE Maximilian Weil, New York, N. Y.

33 Claims. (Cl. 181-27) My present invention relates to sound amplifying systems for various uses in public address installations, but is shown in a particular application for radio receivers, phonographs and combinations thereof,

An object of the invention is to provide an instrumentality of the above type, in which the sound, Whether produced in an auditorium, stadium, or the like, or from a phonograph record or broadcast by radio, appears to emanate from various localities with resultant realism, particularly in the reproduction of orchestral or operatic performances.

Another object is to providea device of the above type presenting an inobtrusive sound amplifier accommodated in a minimum of useful space against the wall of an auditorium or within a cabinet and of rugged and durable construction.

Another object is to provide an instrumentality of the above type inwhich the acoustic amplifier may be readily produced as a separate article of manufacture and coordinated with cabinets of conventional construction now on the market, without necessitating the siightest alteration in the latter, while keeping available the entire height and Width of the cabinet and substantially the entire depth thereof for affording room therein for the radio chassis, phonograph record albums, and the like.

A feature of the invention is the provision of a sound amplifying or diffusing system by which the preferential diffusion paths radiate outwardly from the several parts of the diaphragm, the

25 passage of sound being blocked in a direction normal to the rim of the diaphragm.

Another feature is a compression chamber having contiguous Walls, one of which is the diaphragm and presenting an open annular periphery delivering into an expansion chamber, the walls of which are continuous with the Walls of the compression chamber.

In a preferred embodiment the compression chamber and its diaphragm are of conical shape that the diaphragm itself constitutes a portion ofthe diverging Wall of the acoustic system.

Another more specific feature is the provision of a sound amplifying or diffusing unit having a rim of substantial area adjacent the diaphragm on which the vibrations are impressed, and presenting a complementary filler guiding the sound waves through a narrow diverging path, generally along the height and width of the flat unit, to an open frame-shaped mouth bounded by said rim.

In the application to radio receivers, phonographs, or the like, the sound amplifier, though not necessarily of area greater than that of conventional loud speakers, is distributed along a narrow, elongated region, preferably about the entire outer periphery of the cabinet. The general concept is readily incorporated in that conventional type of cabinet, the front panel of which presents open fretwork about the peripheral frame thereof and usually also adjacent said panel along the side Walls thereof.

According to another feature, the acoustic amplier is in the form of a slab mounted in the cabinet directly in back of the front panel. Within the slab the passages converge from the frameshaped mouth at the front thereof toward the center of the slab, preferably determining an annular throat at the rear face of the slab at which the diaphragm is located.

According to another feature, a conical diaphragm is mounted about the outer periphery of the annular throat and the slab has a generally conical protuberance from the inner periphery of the annular throat extending generally parallel to the conical diaphragm.

According to another feature, the slab is composed of two pieces, a general pyramidal piece having its base registering with the inner periphery of the fretwork frame and a tray-shaped member having its rim registering with the outer periphery of the fretwork frame and presenting a circular opening at its rear face concentric with the conical apex of the pyramidal member, said pyramidal and tray members being secured together in an assembly adapted to be positioned directly in back of the front panel of the cabinet.

In the accompanying drawing, in which is shown one of various possible embodiments of the several features of the invention,

Fig. l is a perspective view of a conventional form of cabinet, in which the invention can be readily incorporated.

Fig. 2 is a fragmentary detail on a larger scale of a corner of the cabinet illustrating the open fretwork.

Fig. 3 is a view in longitudinal cross-section on a larger scale, taken along line 3-3 of Fig. 1.

Fig. 4 is a. fragmentary cross-sectional View taken along line 4-4 of Fig. 1, and

Fig. 5 is a perspective view of the pyramidal element of the acoustic amplifier assembly.

Referring now to the drawing, the conventional cabinet to which the invention has a preferred application, is illustratively shown as a high-boy having legs l0 and a box or generally rectangular cabinet I I. The cabinet has a front panel I2 with a peripheral frame comprising a bottom strip I3, a top strip I4 and lateral strips I5, each with open fretwork as shown in detail in Figs."V

2 and 4.

In this type of cabinet the edge of the lateral walls I6 of the cabinet also has fretwork Il adjacent the front panel, thus forming open fret angle pieces the height of the cabinet, the apertures through which appear in section in Fig. 4. The front panel I2 with its fretwork frame is preferably rigidly disposed in the front of the cabinet, as shown in Figs. 1 and 2, access to the cabinet being afforded through the rear wall I8 thereof.

In conventional use the cabinet is equipped with a radio receiver set and preferably also with a phonograph, equipped with an electric pick-up delivering through the radio amplifier. As best shown in Fig. 3, the radio chassis 2U rests on the bottom of the cabinet. A transverse wall 2l near the top of the cabinet supports the phonograph turntable 22, the shaft 23 of which is operated by a motor 2G under the wall 2I, which motor may be of the spring, but is preferably of the electric type. The lid 25 of the cabinet is hinged, as at 26, for access to the record. The electric pick-up 2li is connected to the radio amplifier by wires 28. The knobs 29 of the radio set are preferably accessible through a compartment 3B below the front panel I2, said knobs being concealed by a fretted door 3l hinged at its lower edge.

The cabinet and installation thus far described are conventional and are ordinarily used with any of various conventional loud speakers, either disposed within the cabinet or apart from the cabinet.

According to the present invention the acoustic amplifier has a mouth of open frame shape directly behind and registering with the open fretwork frame of the cabinet, and preferably also of the adjacent open iretwork edges of the side Walls.

In a preferred specific construction, the acoustic amplifier is in the form of a slab having the dimensions of the panel and snugly lodged in the cabinet substantially directly in back of said panel. The slab in this specific construction is made of two pieces. One of said pieces is a generally pyramidal member having a base 3G extending closely about the inner periphery of the iretted framework, the sides of the pyramidal base merging into a general conical apex 36 rounded at its top 3l; the other or complementary pice is a generally rectangular tray element 33 having a rim 39 adjacent the outer periphery of the fretted panel frame. The tray member has a flat rear wall l0 with a'circular central opening il therethrough through which protrudes the conical tip of the pyramidal member 35.

The inner curved surface of the tray member 3B converges from its rim, as shown, toward the pyramidal member to determine a narrow annular throat l2 between the aperture QI of the tray member and the conical element 36 which protrudes therethrough. The two elements of the sound amplifier slab are preferably assembled together in a unit by interposing therebetween a number of spacer collars 43, through which extend countersunk screws M from the rear face of the slab into the pyramidal member. The slab is preferably of any suitable solid wood which will act as a more or less rigid sound diverging and amplifying conduit.

'I'he throat d2 is near the front panel I2, being spaced therefrom only by the thickness of the slab. Yet the sound diffusing path through the slab acoustic amplifier is long, for the sound wave advances from the annular throat l2 in all directions generally parallel to the panel but outward to the rim thereof, and forward toward the mouth thereof which is immediately in back of the panel I2.

In a preferred construction, a conical diaphragm, known as a cone speaker 50, is aixed at its periphery 5I by means of a metal ring 52 about the annular throat l2 and has an angular divergence such as to extend nearly parallel diverging slightly with respect to the Wall of the conical apex 36 enclosed therein. The conical speaker itself is of more or less conventional construction and presents a fold or ridge of extra material 53, so that the portion therebeyond can vibrate as a unit. The field coil and voice coil (not shown), are embodied in a conventional unit 515, the details of which are not material, mounted aty the apex of the cone speaker 56 and connected by leads 55a to the radio amplifier.

It will be immediately understood that the acoustic `amplifying slab with its cone speaker is readily introduced as a preassembled unit through the rear wall of the cabinet and would be aixed in close contiguity with the front panel by means of vertical cleats 55 Within the cabinet secured by screws 5S to the lateral wall of the cabinet. Additional screws 5l through the cleats attach the latter to the acoustic amplifier slab. Preferably a sheet of vibration absorbing felt 58 is interposed between the acoustic amplier slab and the front panel I2.

It will be noted that the acoustic amplifier slab leaves available for the radio set, for record albums and other articles, the full height and width of the cabinet and occupies but a relatively small part of the depth of the cabinet, and, as above noted, is readily introduced into a cabinet of conventional construction.

The rim of the tray member engages the upper and lower edges of the panel but the lateral portions of the tray rim, as best shown in Fig. 3, engage the fretted lateral strips Il somewhat to the rear of the front panel so that the mouth of the amplifier delivers not only through the open fretted front panel frame but also through the open fretted laterai strips.

In operation vibrations originating in the cone speaker il are diffused and amplified by the slab unit to spread laterally and vertically outward along the elongated` e .ferging path provided and the sound emanatee rnsough the frame shaped mouth of the amplifier which extends the entire length and Width of the fretted peripheral frame of the cabinet and the height of the fretted lateral border.

Considering the operati-on of the acoustic systern as such, apart from the illustrative setting thereof shown in the drawing, it will be seen that the throat of the expansion chamber constitutes an open frame, preferably an annulus, directly connected to the open annular periphery of the compression chamber, one of the walls of which is the diaphragm in which the sound waves originate. y

According to the present invention the vibrations originating in the diaphragm, which is preferably caused to vibrate as a unit, diffuse directly without constriction or reflection into the radiating, and preferably diverging, diffusion chamber.

In the preferred embodiment shown, in which the diaphragm is of conical form, the latter is itself continuous with and functionally a part of the amplifier wall leading to the mouth of the unit.

Thus where in conventional constructions a diaphragm or phone unit is connected to the inlet hole of the horn or expansion unit, the present invention involves building the two elements into a single unit in which the compression chamber constitutes a substantially uninterrupted continuation or functional part of the megaphone or horn element.

In the present invention as applied to a cabinet construction it is not necessary to face the cabinet in order best to hear the performance, but sound waves will reach a person positioned laterally of the cabinet, the sound emerging directly through the lateral fretted border. .An expansive or spacious realistic sound effect is produced due to the narrow but elongated open conformation of the acoustic amplifier mouth.

By the present invention not only is the amplifying effect of the usual cone speaker produced,

vbut upon this, as is noted, is super-added the effect of the acoustic slab which not only effects considerable added amplification and the diffusion, above noted, but lters out the characteristic fundamental note which is a common defect of conventionally installed cone speakers.

While the particular construction of acoustic slab set forth is desirable by reason of its simplicityof construction, it will be understood that such slab could bc molded or otherwise fabricated in a single unitary piece. It will also be understood that instead of a thick slab, the acoustic amplifier could be produced of suiciently rigid sheet material following the contour of v the diverging surfaces in the interior of the slab.

It will also be understood that while it is preferred to extend the mouth of the amplifier about the entire fretted peripheral frame, it is within the scope of the invention to so extend this mouth in any of a wide variety of closed or partly closed courses.

Clearly the invention lends itself for use not only in the conventional constructions of cabinets illustratively shown in the drawing, but can be applied to any of a wide variety of cabinet designs, including drum-shaped or elliptical cabinets, and the like.`

Also it will be readily understood that instead of the fretted open-work frame, other means may be provided in the cabinet to afford a sound out-let, concealed by columns, or the like, from the front of the cabinet.

It is moreover apparent that my amplifier may be built as a separate unit of ornamental character constituting or simluating the frame of a picture bordered by the mouth of the amplifier. Such picture frame embodiment would also lend itself readily to an amplifier or diffuser in an auditorium or stadium for public address systems, thereby obviating the ungainly appearance of loud speaker horns of conventional type.

It will thus be seen that there is herein described apparatus in which the several features of this invention are embodied, and which apparatus in its action attains the various objects of the invention and is Well suited to meet the requirements of practical use.

As many changes could be made in the above construction, and many apparently widely different embodiments of this invention could be made Witho-ut departing from the scope thereof, it is intended that all matter contained in the above description or shown in the accompanying drawing shall be interpreted as illustrative and not in a limiting sense.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent is:

l. A sound amplifying system comprising a cabinet having a diaphragm enclosed therein, means for generating Vibrations in said diaphragm and an acoustic amplifier in said cabinet having a wall continuous with the periphery of said diaphragm, said amplifier having a mouth in the form of a narrow frame substantially enclosing an area of the front of said cabinet.

2. A sound amplifying system comprising a cabinet having a front wall with an area enclosed by a frame of open fretwork, a diaphragm within said cabinet in back of said front wall, spaced L'from said front wall by a distance substantially less than any dimension of saidy front wall, and an acoustic amplifier diverging. from said diaphragm and presenting a mouth in the shape of an open frame immediately in back of said frame of frctwork.

3. The combination set forth in claim 2 in which the acoustic amplifier comprises two corclated elements, one of which is generally conical in shape with its apex near said diaphragm and its base at the inner periphery of said fretwork, the other elements being generally trayshaped, extending about and diverging from said generally conical element with its rim about the outer periphery of the fretwork.

4. A sound amplifying .system comprising a box-shaped cabinet including a generally rectangular front wall presenting an open fretwork peripheral frame, a diaphragm within said box member spaced from said front wall by a distance materially less than the width and height of said cabinet and an acoustic amplifier having a throat adjacent said diaphragm, with outwardly diverging walls extending from said throat and delivering to a mouth in the shape of an open frame of the dimensions of said fretwork frame and adjacent the latter.

5. A sound amplifying system comprising a box-shaped cabinet having a rectangular front Wall with a peripheral frame of open fretwork, an acoustic amplifier within said box and adjacent said front wall, said amplifier comprising two complementary elements, one of generally pyramidal shape with its base adjacent the inner periphery of the fretwork frame, the other generally tray-shaped extending about said first member with its wall diverging from the region of the apex thereof and having its rim substantially about the outer periphery of the fretwork frame and a diaphragm adjacent the apex of said pyramidal member and adapted to deliver its vibrations through the throat defined between the two said complementary members.

6. A sound amplifying system comprising a box-shaped cabinet having a rectangular front panel with an open`fr`etwork frame, a slab-shaped acoustic amplifier unit immediately in back of said panel and of substantially the height and Width thereof, said acoustic amplifier comprising an annular throat at the rear wall of the slab diverging outwardly and forwardly through the thickness of said slab to an open frame-shaped mouth, extending along the fretwork frame of the panel, and in close proximity to the latter, and diaphragm means adjacent said throat.

'7. The combination set forth in claim 6 in which the slab-shaped acoustic amplifier includes two complementary elements, the first of which comprises a generally pyramidal conformation, having its base substantially at the inner periphery of the open fretwork frame, the other of which comprises a generally rectangular trayshaped conformation centrally perforated to accommodate the apex of said pyramidal conformation, diverging from the walls of the latter and having its rim substantially about the outer periphery of said frame. l

8. The combination set forth in claim 6 in which the slab-shaped acoustic amplifier comprises two complementary elements, the first of which comprises a general pyramidal conformation, having its base substantially at the inner periphery of the open iretwork frame, the

other of which comprises a generally rectangular tray-shaped conformation centrally perforated to accommodate the apex of said pyramidal conformation, diverging from the walls of the latter, and having its rim substantially about the outer periphery of said frame, spacer collars between the pyramidal and tray conformations and screws extending through said collars to assemble said pyramidal and tray conformations into a unit.

9. A sound amplifying system comprising a I box-shaped cabinet having a front panel presenting a narrow elongated area of open fretwork, and an acoustic amplifier immediately in back of said panel presenting a mouth, extending substantially along and of the dimensions of said narrow elongated area of fretwork, said amplier having walls converging from the sides of said fretted area, extending generally lengthwise in back of said panel to a throat near the panel and substantially midway between the opposite edges thereof.

10. A sound amplifying system comprising a generally rectangular cabinet including a front panel, and having angle pieces at certain edges thereof with open fretwork therein, an acoustic amplifier wihin said box having its mouth opening into and extending along both Wings of said fretted angle pieces, the amplier presenting walls converging toward each other and having an axis directed generally parallel to said panel to a constricted throat near said panel, but substantially midway between the top and bottom and substantially midway between the lateral borders thereof.

11. A sound amplifying system comprising a box-shaped cabinet having a front panel with an open fretwork frame about the periphery thereof, the lateral walls of said cabinet also having open fretwork at the edges thereof adjacent said`panel, and means for diffusing sound originating within said cabinet through the open fretwork frame, said means comprising an acoustic amplifier having its mouth in the form of an open rectangular frame, with the fretwork of said panel and lateral Walls disposed between the inner and outer periphery of said mouth, said amplifier including Walls converging inwardly frornnsaid mouth along an axis generally parallel to said panel to a throat near said panel, said throat having means for accommodating adiaphragm.

12.` A sound amplifying system comprising an article of 'furniture having a vfront panel with open fretwork about the periphery thereof and further open fretwork extending along the lat-= aosaioe eral walls thereof adjacent said front panel, an acoustic amplifier in the form of a slab within said container and immediately in back of said panel, said slab presenting a frame-shaped mouth extending along and delivering through all said fretted area, said slab presenting walls in the interior thereof converging from said mouth and directed generally parallel to said panel toward a throat at the rear face of said slab and substantially symmetrical thereof, said slab having means adjacent said throat for accommodating a sound producing diaphragm.

13. A sound amplifying system comprising a box having a panel at the front thereof provided with fretwork about the periphery thereof, an acoustic amplifying device directly in back of said panel presenting an open frame-shaped mouth along and in back of said fretted area, said amplifier presenting walls converging from the outer and inner edges of said fretwork and directed generally parallel to said panel to an annular throat in back of said panel and spaced from said panel by a distance materially less than the Width of said panel, and a conical diaphragm aiiixed about said annular throat.

14. A sound amplifying system comprising a generally rectangular box having a front panel with an open fretted frame, an acoustic amplifier presenting a mouth directly in back of said fretted frame and of substantially the dimensions of the latter, said amplifier presenting walls converging toward each other from the outer and inner borders of the fretted frame, said walls extending generally parallel to said frame and forming an annular throat in back of but near said panel, and a conical diaphragm axed about the outer periphery of said throat.

15. A sound amplifying system comprising a generally box-shaped cabinet having a rectangular front panel with a peripheral open fretted frame, an acoustic amplifier in the form of a slab directly in back of said panel and of the dimensions of the latter, said slab presenting a frame shaped mouth registering with said fretted frame, said slab presenting internal walls converging toward each other from the rectangular mouth to determine an annular throat at the rear face of the slab, the slab having a generally conical protuberance encircled by said annular throat, and a conical diaphragm secured to the outer periphery of said annular throat with its walls extending generally parallel to said conical protuberance.

16. As an article of manufacture, an acoustic amplifier unit for use in a conventional cabinet of the type including a front panel with an open fretwork peripheral frame, said amplifier unit comprising a generally slab-shaped member/"fof the dimensions of said panel presenting a frameshaped mouth about its periphery, of dimensions adapted to register with the open fretwork frame, said slab having internal passages converging from said mouth and directed generally toward the rear Wall of the slab, said passages opening as an annular throat substantially at the middle of the rear face of said slab, said slab presenting a conical protuberance from the inner periphery of said annular throat.

17. As an article of manufacture, an acoustic amplifier unit for use in a conventional cabinet of the type including a front panel with an open shaped mouth about its periphery, of dimensions `conical protuberance from the inner periphery of said annular throat, and a conical diaphragm secured about the outer periphery of said annular throat and extending generally parallel to said conical protuberance,

18. As an article of manufacture, an acoustic amplier unit for use in a conventional cabinet of the type including a front panel with an open fretwork peripheral frame, said amplier unit including a generally slab-shaped assembly, comprising a generally pyramidal element having a rectangular base corresponding to the inner periphery of the open fretwork, a generally trayshaped member having a rim of dimensions corresponding to the outer periphery of the fret- Work and diverging from said pyramidal member, and presenting a central opening for the apex of said pyramidal member, said pyramidal member being generally conical near its apex to determine an annular throat in the aperture in said tray member, spacer collars between the pyramidal and tray member and fastening members through said collars retaining the pyramidal and the tray amplifier unit for use in a conventional cabinet of the type including a front panel with an open fretwork peripheral frame, said amplifier unit including a generally slab-shaped assembly, comprising a generally pyramidal element having a rectangular base corresponding to the inner periphery of the open fretwork, a generally trayshaped member having a rim of dimensions corresponding to the outer periphery of the fret- Work and diverging from said pyramidal member, and presenting a central opening for the apex of said pyramidal member, said pyramidal member being generally conical near its apex to determine an annular throat in the aperture in said tray member, spacer collars between the pyramidal and tray member and fastening members through said collars retaining the pyramidal and the tray members as a unitary assembly, and

a conical diaphragm secured to the rear face of.

said tray member about the circular opening therein and extending generally parallel to the conical apex of the pyramidal member.

20. A sound diffusing unit comprising a diaphragm, a relatively at dive`rging Wall projecting from and presenting a rim near said diaphragm, and a diverging ller enclosed by said 'rim for guiding substantially all of the effective vibrations originating at said diaphragm along a diverging path between said filler and said wall to be delivered from said unit through a frameshaped mouth.

21. A sound diffusing unit having a thickness small compared to its height and width, presenting a diaphragm at the rear thereof, and a mouth at the front thereof of area much less than that of the face of said unit, said unit presenting a sound conducting passageway generally parallel to the face thereof having a wall continuous with and diverging from the periphery of said diaphragm to said mouth.

22. A sound diffusing unit having a thickness but a small fraction of its face area having a diaphragm near the rear thereofand a mouth substantially peripherally thereof, said unit presenting a sound directing wall therein diverging from and continuous with the periphery of said diaphragm forwardly and outwardly about the outer periphery of said mouth, said unit presenting a diverging ller extending from near said diaphragm to the inner periphery of said mouth.

23. An ornamental sound diffusing unit having a thickness of a small fraction of its face area, having a diaphragm near the rear thereof, a mouth in the shape of a frame peripheral of the front of said unit, a wall within said unit diverging from and continuous with the periphery of said diaphragm to the outer periphery of said mouth, a diverging ller rigid with said unit extending from the Vicinity of said diaphragm outwardly to substantially the plane of said mouth and defining the inner periphery of said mouth.

24. A sound amplifying and diffusing system comprising a diaphragm and acoustic amplifying means radiating from various parts of the periphery of said diaphragm, and presenting preferential paths of sound diffusion, said system including means blocking the advance of the sound waves in a direction normal to the rim of the diaphragm.

25. An acoustic system comprising a pair of complementary continuous wall members presenting therebetween a mouth and spaced from each other throughout the areas thereof, .one of said walls including a diaphragm and the corresponding portion of the complementary wall forming a compression chamber in coaction with said diaphragm.

26. An acoustic system comprising a compression chamber including a diaphragm and a wall contiguous thereto but spaced therefrom, and a diffusion chamber presenting complementary walls substantially continuous with and extending outward from the respective peripheries of the compression chamber.

27. An acoustic system comprising a compression chamber having complementary spaced Walls, one of which constitutes a diaphragm and presenting an open periphery, and a diffusion chamber having complementary walls directly connected to the peripheries of and substantially continuous with the walls of said compression chamber.

28. An acoustic system including complementary relatively non-vibratable Walls, one of said walls having an opening therein contiguous to the complementary wall, and a diaphragm having a periphery closing said opening and extending contiguous to said complementary Wall to determine in cooperation therewith a compression chamber peripherally delivering to the diffusion chamber determined between the regions of said walls about said diaphragm.

29. An acoustic system comprising a generally conical diaphragm, a relatively non-vibratable diverging wall connected to and substantially continuous with the periphery thereof, and a complementary relatively non-vibratable conical member extending near its apex in contiguity to the area of said conical diaphragm and determining the inner wall of a frame-shaped expansion chamber of which said diverging wall constitutes the outer wall.

30. An acoustic system comprising a generally conical non-vibratable member, a complementary wall member enclrcli 1g and diverging from said conical member an@ presenting an opening through which the apex of said conical member protrudes, and a conical diaphragm connected to said encircling Wall member and extending in contiguity to but spaced from said apex.

31. An acoustic system comprising a support member having a circular opening, a cone diaphragm connected at its periphery about said opening, a second support member, a non-vibrating cone carried thereby complementary to and placed in close proximity to said diaphragm to form a compression chamber in cooperation therewith, said system presenting complementary Wall members substantially continuous with the constituent parts of said compression chamber, constituting a diffusion chamber and presenting a mouth remote from said diaphragm.

32. An acoustic system comprising a pair of complementary generally conical wall members spaced from each other throughout their areas,

MAXIBHLIAN WEIL.