US1790120A

US1790120A - Loud-speaker

Info

Publication number: US1790120A
Application number: US111149A
Authority: US
Inventors: Adolph A Thomas
Original assignee: Individual
Current assignee: Individual
Priority date: 1926-05-24
Filing date: 1926-05-24
Publication date: 1931-01-27
Anticipated expiration: 1948-01-27

Description

Jan. 27, 1931. A1 THQMAS 1,790,120

LOUD SPEAKER Filed May 24 1926 2 Sheets-Sheet 1 v Jan. 27, 1931. A A TH AS 1,790,120

LOUD SPEAKER I Fild May 24 192 2 Sheets-Sheet 2 70 INVENTOR' Patented Jan. 27, 1931 UNITED STATES ADOLPH A. THOMAS, OF NEW YORK, N. Y.

LOUD-SPEAKER Application filed Kay 24,

My invention relates to electric sound-reproducing devices and its object is to provide a loudspeaker in which a small diaphra amplifying through a horn is com- 6 bine with a large cone-shaped. diaphragm.

This produces an instrument capable of reproducing the upper and lower registers of sound frequencies with equal fidelity.

In the loudspeaker of my invention, there is a hollow base on which is mounted a horn for amplifying the vibrations of a small diaphragm. Within the base is supported a large diaphragm in horizontal osition. This diaphragm is conveniently but not necessarily) of the well-known cone type.

Both diaphragms are simultaneously operated by suitable electromagnetic mechanism. The vibrations of the large diaphragm pass out of the hollow base through openings into 2 the free air. The bottom of the base may be closed by a sounding boardto accentuate or reinforce the air vibrations produced by the large diaphragm. Thus, in the" operation of the instrument, the higher tones issue'out of the horn, while the lower tones come from the base chamber.

In a preferred embodiment of my invention, the small upper diaphra is controlled by a coil or coils which ten to accentuate the higher frequencies, while the large diaphragm in the base is controlled by one or more coils so connected in circuit as to cause the lower frequencies to predominate. In this way, the operative control of each dia-,

phragm is independent of the other. In order to regulate the action of the controlling coils, I connect a variable choke coil across the coils of the small diaphragm and a variable condenser across the coils of the large diaphragm. These variable devices are mounted on the base so as to be adjustable by simply turning a knob or the like. This enables the operator readily to vary the quality of reproduction to suit his own musical taste.

In addition to means forcontrolling the quality of reproduction, I may also provide my new loudspeaker with means for control- I ling the volume or loudness of the reproduced sound. At the present time I prefer an ad- 1926. Serial No. 111,149.

justable magnetic shunt for regulating the efi'ective strength of the magnet structure.

The accompanying drawings illustrate several embodiments of my invention, wherein- Fi 1 re resents a vertical cross-section of 5 one orm o my inproved loudspeaker, a portion of the base and the large diaphragm being broken away for lack of space;

Fig. 2 is a plan view on the broken line 2-2 of Fig.1; I 50 Fig. 3 shows an enlarged detail view of the adjustable mounting of the armature on the cone diaphragm;

Fig. 4 is a view similar to Fig. 1, but at ri ht-angles thereto; o5

ig. 5 is a detached view in plan to show the connections for adjusting the core of the choke coil which is shunted across the coils that operate the upper diaphragm;

Fig. 6 illustrates in cross-section a modified construction wherein the cone diaphragm is mounted with its apex pointing'downwardly;

Fig. 7 is a fragmentary detail view showing a knob for controlling the volume or loudness of the cone diaphragm;

Fig. 8 shows a parallel arrangement of the magnets for the two diaphragms, making in efiect a single magnet controlled by one mag- L netic shunt; and I Fig. 9 indicates diagrammatically suit- 30 able circuit connections for the controlling coils.

Before beginning a detailed description of the drawings, I want to make it plain that the various figures are not intended to reps5 resent accurate shop drawings. On the contrary, I have purposely shown various parts aluminum, whichis light, strong and nonmagnetic. The particular shape and dimensions of the base will naturally vary in accordance with the size and mounting of the cone diaphragm, as will presently become clear. Ordinarily, base B will be circular in design; for example, it may be a flat or corrugated disk, and may be of metal, wood and other suitable acoustic materials. The diaphragm C is rigidly clamped at its periphery to. an annular flange or shoulder 10 at the bottom of the base by means of a ring 11 secured to flange 10 by screws 12. In this instance, the clamping ring 11 is part of a cone-shaped disk 13 arranged parallel with the diaphragm and forming a bottom closure for the base chamber 14. Disk 13 may be made of resonant material to act as a sounding board for reinforcing the vibrations of diaphragm C. The base B is provided with legs 15 to hold the disk or board 13 clear of the support on which the instrument stands and allow the vibrations of the disk to escape into the free air all around. The vibrations of diaphragm 0 pass freely out of the base chamber 14 through openings 16 ar ranged radially all around the conical wall of the base. In Fig. 1 these openings have been purposely omitted, so as not to obscure certain parts within the base chamber.

On base B is mounted a cylindrical casing 17 having a bottom plate 18 and an outer flange 19. These parts are preferably cast or molded as a unit out of suitable nonmagnetic material, such as aluminum, bakelite, etc. The flange 19 rests on an annular seat 20 at the top of base B, and screws 21 secure the casing 17 rigidly to the base. The seat 20 is preferably depressed to provide a circular recess 22 into which flange 19 fits snugly to afford additional holding means for the casing and at the same time facilitate assembling of the parts. In the upper end of casing 17 is mounted a diaphragm D. A cover plate 23, removably secured in position by screws 24, holds the diaphragm D firmly clamped between a pair of gaskets or washers 25 of rubber, felt or like material. A circular ledge 26 formed within the casing acts as a support for the diaphragm. The cover plate 23 is provided with a tubular extension 27 for receiving the neck of a horn 28 through which the vibrations of diaphragm D are amplified. This diaphragm may be magnetic, or it may be of non-magnetic material, such as aluminum, German silver, wood, etc. If non-magnetic, diaphragm D carries an armature 29, preferably in the form of a small thin iron disk attached centrally to the underside of the diaphragm.

The electromagnetic mechanism for operating the diaphragms C and D comprises, in

best shown in Figs. 2 and 8. As the magnets are flat, they can be stamped out of steel plates. The circular form of the magnets provides a maximumlength of magnetic path in the cylindrical casingl'l'. To the polar limbs of each magnet are fastened pole pieces 32, which project at right angles to the body of the magnet. The pole pieces of the upper magnet M project upwardly toward the small diaphra m D, andthose of the lower magnet M project downwardly toward the large diaphragm C. By making the pole pieces 32 L-shaped, it is possible to secure them firmly to-the polar limbs 31 (as by screws 33) over a large contact area. In Figs. 1 and l, the two magnets are so mounted'that their polar limbs extend at right angles to each other, for a purpose that will later be explained.

Onthe pole pieces of magnet M are mounted coils K, and on the pole pieces of magnet M are mounted coils K. Since each pair of coils is connected in series, these four coils are in effect but two coils, and so I shall refer to them as coil K and coil K, respectively.

As seen in Figs. 1 and 4, the pole pieces 32 of magnet M terminate close to armature 29 of diaphragm D, or close to the diaphragm itself if the latter is of magnetic material. The pole pieces of magnet M extend toward the armature 34 of diaphragm C. This armature is preferably in the form of a small disk adj ustably secured to the diaphragm to permit regulation of the normal airgap between the armature and the pole pieces. The two armatures should be large enoughto span the pole pieces fully, not only transversely ,buiTalso in the direction of their length. The enlarged view of Fig. 3 illustrates a practical way of mounting the armature 34 for axial adjustment. The diaphragm C carries at the center a bushing 35 which is screw-threaded inside and outside. The bushing is fixed in position by means of a pair of cone-shaped disks 36, which engage the diaphragm on opposite sides. The upper disk 36 bears a ainst (or is made integral with) a collar 3% on bushing 35. A nut 38 screwed on the bushing holds the disks 36, and thereby the bushing itself, rigidly clamped to the diaphragm. A screw-threaded rod or bolt 39, secured to the center of armature 34, passes through bushing 35 in which it is axially adjustable, as by means of a screw-driver or like implement inserted into the head 40. The disk or sounding board 13 is provided with a small central opening 41 to permit access tothe armature bolt 39 without dismantling any portion of the in- Figs. 1 and 5. The iron core 50 is axially adstrument. A coil spring 42, or equivalent justed with respect to the coil by a stiff cam means. employed to hold the bolt 39 in ad wire or rod 51 secured to a shaft 52 which is justed position without the possibility of ratturned in either direction by knob 48. The tli'ng during the vibrationsof the diaphragm. outer end of core 50 has'an eye 53 through The controlling coils K and K are conwhich passes the cam wire 51. In Figs. 1 nected in parallel to the leads l3, wh'ch may and 5, the core 50 is almost entirely withterminate in a plug 4H, as diagrammatically indicated in Fig. 9. The ends of the upper coil or coils K pass into the base chamber 14 througha small hole 45 in the bottom plate 18. The leads 43 pass through a conveniently located opening (not shown) in base B. thcr explanation, that current impulses passquency cause simultaneous vibration of diaphragms C and D to reproduce the sound waves of which the variable current impulses are (as it were) an electrical representation. Since the tendency of the large diaphragm C is to accentuate the lower register on the musical scale, while diaphragm D tends to accentuate the upper register. it is possible, by correctly designing these diaphragms, to reproduce the whole range of audio-freque'ncy tones with practically uniform intensity. It will he noticed that the bottom plate 18..which preferably non-resonant, acoustically separates the interior of casing 17 from the base chamber 14. so that the vibrations of either diaphragm do not disturb the vibrations of the other.

\Yhile the diaphragms D andC will naturally respond best to the higher and lower bands of frequencies. even though all frequencies pass through coils K and K. I prei'er so to modify the action of the controlling coils that the higher frequencies pass most easily through coil K of diaphragm D and the lower frequencies pass most easily through coil K of diaphragm C. To this end. a choke coil 46 is connected across coil K. and a condenser 47 is connected across coil K. The choke coil tends to absorb low-frequency in pu'lses. allowing high frequencies to traverse the coil K. The action of the condenser is the reverse, in that it allows low frequencies to pass through coil K. It'is clear that by regulating the self-induction value of choke coil 46 andthe capacity of condenser 47, the operation of coils K and K is correspondingly controlled. That is to say. it is ble in this way to select the range of frequencies that shall pass through (or predominate in) coil K and coil K. In 1. the regulating

devices

46 and 47 aremounted on base ll in such positionthat a turnable knob 48 varies the self-inductance ot' choke coil 46. while a knob 4-9 varies the capacity of condenser 47. It is not necessary to show any structural details of a variable condenser. because there are many familiar makes of that type of condenser on the market. A simple way of regulating choke coil $6 is shown in It will be understood without furmg through coils K and K at audio fre- 4 poss1- drawn from coil 46. so that the choking action of the coil is at a minimum. As the cam 51 is turned clockwise (as viewed in Fig. the core is moved into the coil 46 to increase its choking cfi'ect. \Vhen the cam 51 is in the position indicated by dotted lines 51, the core 50 is entirely within the coil. so that now its self-imluctance is a maximum. the extreme in and out positioiis of the inner core. any intermediate position may be obtained. The iron core remains in adjusted position. since. the connection between the core and cam 51 does not permit the core to be suckedinto thecoil by the magnetic action of the latter. A strap 54. attached at its ends to the slanting wall of base B. holds the choke coil firmly in position. If desired. strap 51 may be provided with an arm or extension to guide the core in its axial movements.

.ltwill be understood from the preceding paragraph that the operator can readily control the frequency-selecting action of coil K for the horn diaphragm D and of coil K for the base diaphragm C by simply turning the

knobs

48 and 49. I have thus provided simple means for controlling the quality of rcprmluction of the instrument for each diaphragm. This is not intended as a regulation of mere volume or loudness. for which separateprovisions are made, as now to be described.

Referring to Figs. 1 and 2. there is a, mag netic block 56 (preferably of soft iron) arranged to slide over the bottom plate 18't0- ward and away from the pole limbs 31 of magnet M. The plate 18 has a lug 57 with a screw-threaded hole through which passes a screw-threaded rod 58 of non-magnetic material. The inner end of rod 58 is rotatably connected to the magnetic block 56. as indicated at 59. The other end of the rod extends outside the casing 17 where it is provided with a knob 60 for easy manipulation. WVhen the knob 6Q is turned in one direction (say, clockwise). the rod 58 pushes the magnetic block 55 away from the-pole pieces toward the neutral portion of the magnet. In Figs. 1 and 2, the block 56 is practically without effect on the normal field flux across the pole pieces. \Vhen the knob is turned the other way, the-magnetic block is drawn toward the polar limbs of the magnet. The closer it approaches the polar limbs 31, the more flux does it short-circuit and the weaker become the pole pieces 32 that provide the effective flux for armature 29 of diaphragm D. In other words. the ma netic block 56 acts as a shunt for the field flux and by its Between "obtained.

In exactly the same way is the loudness of the large diaphragm C controlled by an adjustable magnetic shunt 56 (see Fig. 4), which arranged to slide in a direction at right angles to that of block 56. so that neither shunt block shall affect the other magnet. For this purpose the magnets M and are arranged at right angles to each other, as previously explained. The block 56' is shifted back and forth by means of a non-magnetic rack-bar (i1 slidably supported in a lug (52 depending from plate 15.. The teeth of rack-bar ()1 are in mesh with a pinion (33 fixed at the inner end of a rotary stud 64 mounted on base li. as shown in F g. 4. A knob (35, or other finger piece. permits 'ready adjustment of magnetic block 56.

\Vhat has been said about the position of magnetic shunt 56 controlling the ett'eetive strength of magnet. M, is applicable to magnetic block 56' in similarly controlling the operative strength of magnet M and the loudness of diaphragm C. in Fig. l. the shunt block 56 is shown in loud position. while in Fig. 6 it is shown in soft posi tion. In fact, when the

magnetic shunt

56 or 56 is in contact with the polar limbs of the associated magnet. there is practically no flux passing through the pole pieces 32. so that the adjacent diaphragm is rendered inoperative. This atl'ords an easy way to cut out either diaphragm when desired.

The only ditlerence between Fig. (3 and the other figures is that diaphragm C is supported in base l)" with its apex pointing down. in this instance. the cone diaphragm is clamped between an inner ring (it; and an outer ring (ii. The inner ring has a series of lugs tie through which pass screws {39 to secure the diaphragm against the underside of the base. The bottom closure or sounding hoard i2, is fastened by screws T0 to interior lugs T1 on the base. The lugs T1. be ng spaced at. intervals. do not prevent the insertion of diaphragm held in clampings (it; and 67. because the ring or; can be so positioned that the lugs (38 pass by the lugs Tl. The vibrations of diaphragm pass into the free air through openings 72 in the base. 'hat has been previously said about the operation and control of the diaphragms in l igs. k5. is tally applicable to Fig. t3. without the need r petition.

ii ill e seen from the preceding oescrip- ,tion that I have provided a combined horn and cone loudspeaker of compact construction and neat appearance. The large diaphragm is concealed in the base, and therefore adds little to the dimensions of an ordinary horn speaker. except that a broader base is needed, depending upon the diameter of the cone diaphragm. These diaphragms run all the way from about six inches to eighteen inches or more. A wide base is not objectionable, since it can be made ornamental in color and design, and furthermore it adds stability to the instrument. The 'ease with which the quality and volume of reproduction can be controlled increases the usefulness of this double loudspeaker. It is not necessary, however. that all the controlling connections previously described shall be embodied in the same device.

Various changes and modifications may be resorted to in practising my invention. For instance. instead of arranging the magnets M and M at right angles to each other and having a separately controlled magnetic shunt for each. I may arrange the magnets in parallel relation with a single shunt; for both. as indicated in Fig. 8. The supporting plate 18 for the magnets may be separate from casing 17 and formed as'an integral part of the top of the base. My invention is not limited to any specific construction or mounting of electromagnetic mechanism for operating the two diaphragms. and what I have shown in the drawings is to be regarded as illustrative and not restrictive. The basic idea of operatively mounting a large hornless diaphragm horizontally in the base of a loudspeaker having also a small diaphragm that amplifies through a horn. may be embodied in other ways than herein set forth. It is evident that certain features of my invention may be used without other features.

Thus, in a simplified form of loudspeaker. theff cone portion may be constructed without the horn portion.

What I claim as my invention is:

l. loudspeaker having a base constructed to provide an open chamber. a horn supported on said base. a diaphragm acoustically connected with said born, a large direct-acting diaphragm operatively mounted in said open base chamber and acoustically disconnected from said horn. whereby said large diaphragm iscdmpletely housed in said base and yet freely open to the outer air. and electromagnetic means for simultaneously operating both diaphragms.

2. A loudspeaker comprising a hollow base freely open to the outer air. a small diaphragm mounted in the upper part of said base. a horn supported on said. base and zu-oustically connected with said small diaphragm. a large diaphragm mounted horizontally in said base below said small dia phragm and completely housed in said base,

the vibrations of said large diaphragm passing through the open base into the free air, means in said base for preventing the vibrations of the large diaphragm passing through the horn, and electromagnetic means in said base for simultaneously operating said diaphragms.

3. A loudspeaker having a base provided with a-small upper' chamber and a large lower chamber, a partition between said chambers, said lower chamber having lateral sound openings, a horn extending from said upper chamber. a small diaphragm in said upper chamber. a large diaphragm in said lower chamber, said diaphragms being arranged substantially in horizontal position, and electromagnetic mechanism mounted on said partition for actuating said diaphragms, the vibrations of the large diaphragm passing through said lateral openings into the outer air.

4. A combined horn and cone loudspeaker having a hollow supporting base in which a direct-acting cone diaphragm is operatively mounted in horizontal position, said base completely enclosing said con diaphragm and having openings for the emission of sound from said diaphragm, a horn supported on said base, a diaphragm acoustically connected with said horn, and electromagnetic mechanism for operating said diaphragms.

5. In a loudspeaker,'a hollow supporting structure provided with two chambers, a small diaphragm in one'chamber,. a large diaphragm in the other. chamber, said hollow supporting structure enclosing both diaphragms, a sound-amplifying,passage leading from said first chamber, electromagnetic mechanism within said structure for operating said diaphragms. said structure having openings through which the vibrations of the large diaphragm pass into the outer air, and a partition. in said structure for acoustically separating the chamber of the large diaphragm from said amplifying passage.

6. In a loudspeaker, an. upright hollow base having a sound passage on top for communicating with a horn, "a horizontal diaphragm mounted in said base adjacent said passage for sending sound vibrations therethrough, a second diaphragm enclosed in said hollow base and supported in horizontal position below said first diaphragm, a partition arranged in said base to acoustically separate the second diaphragm from said sound passage, and electromagnetic mechanism mounted on said partition for operating said diaphragms, said base having openings for the escape of sound waves from said second diaphragm.

7. A loudspeaker comprising a hollow non magnetic casing provided with a base and having sound openings above said base, a direct-acting cone diaphragm supported horizontally in said casing above said base and freely open to the outer airthrough said sound openings, said cone diaphragm being completely housed in said hollow casing, an electromagnetic driving unit mounted in said casing above said diaphragm, and means whereby said unit is insertable into and removable from said casing without disturbing the diaphragm which is supported inde p'endently of said unit.

8.- In a loudspeaker, a hollow base provided with lateral sound openings, a cone diaphragm enclosed in said hollow base and supported horizontally therein with its apex pointing upwardly, an armature fixed to the center-of said diaphragm, and electromagnetic mechanism mounted in said base above said diaphragm for operating the same throughthe medium of said armature, said diaphragm being supported independently of said mechanism.

9. In a. loudspeaker, a cone diaphragm provided at the center with an internally threaded bushing extending axially of the diaphragm, means for rigidly holding said bushing in place, a screw mounted in said bushing and wholly supported thereby, said screw projecting at one end' out of said bushmg, an armature fixed on said projecting end of'the screw which is adjustable in said bushing, resilient means engaging said screw to hold the same firmly in adjusted position during the vibrations of the diaphragm, and electromagnetic means in operative relation to said armature.

10. In a sound-reproducing device, a hollow base open for the passage of sound, a direct-acting cone diaphragm enclosed in said hollow base and supported horizontally therein, an electromagnetic unit in said base for operating said diaphragm, and means whereby said diaphragm is supported independently of said unit.

11. In a loudspeaker, a hollow base provided with sound openings, a cone diaphragm horizontally supported in said base with its apex pointing upwardly, a atone-shaped sounding board mounted in said base below said dia hragm, said "board also forming a closure or the bottom of the base, and electromagnetic mechanism mounted in said base above said diaphragm for operating the same.

12. In a loudspeaker, a pair of diaphragms having different acoustic properties, electromagnetic meohanism for simultaneously operating said diaphragms, and magnetic means adjustable independently of said mechanism and said diaphragms for con trolling the operative flux of said mechanism to regulate the volume of reproduction of each diaphragm, said means permitting either diaphragm tobe cut out of operation.

13. Ina loudspeaker, a magnet structure having two pairs of pole pieces extending in opposite directions, a small diaphragm mounted on one side of said structure in operative relation to one pair of pole pieces, a horn acoustically connected with said small diaphragm, a large direct-acting diaphragm mounted on the other side of said structure in operative relation to the other pair of pole pieces, a controlling coil on each pair of pole pieces, said coils being connected in parallel to permit independent operation" of said diaphragms, and means for acoustically disconnecting said large diaphragm from said horn.

14. In a loudspeaker, a magnet structure having two pairs of pole pieces extending in opposite directions, a small diaphragm mounted on one side of said structure in operative relation to one pair of pole pieces, a horn acoustically connected with said small diaphragm, a large direct-acting diaphragm mounted on the other side of said structure in operative relation to the other pair of pole pieces, a controlling coil on each pair of pole pieces, said coils being connected in parallel to permit independent operation of said diaphragms, means for acoustically disconnecting said large diaphragm from said horn and manually controllable means for varying the effective response of said coils to difierent bands of frequencies.

15. A combined horn and cone loudspeaker having electromagnetic mechanism mounted between the two diaphragms for simultaneously operating the same, and manually controllable means for regulating the loudness of the horn diaphragm and the cone diaphragm independently. of each other, said means permitting either diaphragm to be cut out of operation.

16. A loudspeaker comprising a hollow base having sound openings, a horn supported on said base, a small diaphragm mounted in the upper part of said base and acoustically connected with said horn, a large diaphragm supported horizontally within said base, electromagnetic mechanism for operating said diaphragms, said mechanism including a controlling coil for each diaphragm, a variable. condenser and an adjustable choke coil mounted within said base, said condenser being connected across the operatin coil of the large diaphragm and said cho e coil being connected across the operating coil of the small diaphragm and a pair of finger pieces on the outside of said base for separately adjusting said condenser and said choke coil and thereby varying the effective response of said operating coils to difierent bands of frequencies, whereby the quality of reproduction of either diaphragm may be varied as desired.

17 A loudspeaker comprising a hollow base member open at the top and having an annular seat around the top opening, a casing adapted to rest on said seat, said base vmember being of considerably greater diameter than said casing, means for securing said casing in position on said base member, said casing having a bottom plate: which closes the top of said base member, a diaphragm mounted in said casing, a horn connected to the upper end of said casing for amplifying the vibrations of said diaphragm, a large diaphragm supported horizontally in said hollow base member, and electromagnetic mechanism secured to said bottom plate for simultaneously operating said diaphragms independently of each other, said mechanism being arranged partly on the upper side of said plate and partly on the underside thereof.

18. A loudspeaker comprising a hollow base provided with two chambers acoustically separated from each other, said chambers having sound openings leading to the outer air, a diaphragm mounted in one of said chambers, a second diaphragm mounted in the other chambers, said hollow base completely enclosing both diaphragms, which have different natural frequencies to accentuate high and low tones, and electromagnetic mechanism in said base for operating said diaphragms. 3

19. A combined horn and cone loudspeaker comprising a hollow base, a horn mounted on said base, a horizontal partition in said base to provide a small upper chamber and a large lower chamber, said chambers; being acoustically separated by said partition, said lower chamber having sound openings to the outer air, a small diaphragm arranged in said upper chamber and acoustically connected with said horn, a large direct-acting diaphragm in said lower chamber, said hollow base completely enclosing said diaphragms, and electric means in said base for operating said diaphragms.

20. A combined horn and cone loudspeaker comprising a-hollow base, a horn mounted on said base, a horizontal partition in said base to provide a small upper chamber and a large lower chamber, said chambers being acoustically separated by said'partition, said lower chamber having sound openings to the outer air, a small diaphragm arranged in said upper chamber and acoustically connected with said horn, a large direct-acting diaphragm in said lower chamber, electric means in said base for operating said diaphragms, and a sounding board arranged horizontally 1n said lower chamber to amplify the vibrations of said direct-acting diaphragm.

21. A combined horn and cone loudspeaker having a hollow base in which a cone diaphragm is completely housed and operatively mounted in horizontal position, a horn rigidly supported on said base, a diaphragm acoustically connected with said horn, said cone diaphragm being acoustically disconnected from said horn, electromagnetic mechanism in said base for operating said diaphragms, and means in. said base for regulating the loudness of the two diaphragms independently of each other.

22. A combined horn and cone loudspeaker having a hollow base in which a cone diaphragm is operatively mounted in horizontal position, a horn rigidly supported on said base, a diaphragm acoustically connected with said horn, said cone diaphragm being acoustically disconnected from said horn, means in said base for independently regulating the loudness of the two diaphragms to obtain the best acoustic blending of the tones, and a pair of manually adjustable members outside said base for controlling said means independently for each diaphragm.

23. A loudspeaker having a plurality of diaphragms of different acoustic properties, electromagnetic mechanism for simultaneously operating said diaphragms, and mag netic means independent of said mechanism and said diaphragms for influencing said mechanism to simultaneously regulate the volume of reproduction of all diaphragms. 24. In a loudspeaker, a pair of diaphragms having different acoustic properties, electromagnetic mechanism for simultaneously operating said diaphragms, and magnetic means adjustable independently of said mechanism and said diaphragms for controlling the operative fiux of said mechanism to regulate the volume of reproduction of each diaphragm independently of the other.

25. An electric acoustic device comprising a hollow upright casing in which a cone 'diaphragm is supported in horizontal position, said casing being open for the passage of sound from said diaphragm into the outer air, electromagnetic mechanism in said casing for operating said diaphragm, and a resonance board mounted horizontally in said casing in operative relation to said diaphragm, the vibratory surface of said diaphragm being freely exposed in said chamber awayfrom said mechanism.

26. An electric acoustic device comprising a hollow upright casing in which a cone diaphragm is supported in horizontal position. said casing being open for the passage of sound from said diaphragm into the outer air, electromagnetic mechanism in said casing for operating said diaphragm, and a cone-shaped board mounted in the casing opposite said diaphragm, the apices of said diaphragm and board extending toward each other, whereby said diaphragm and board form a circular acoustic chamber with outwardly diverging upper-and lower walls which deflect the sound through the open casing into the outer air.

27. In a loudspeaker, the combination of a hollow base enclosing a large direct-acting diaphragm and having sound passages through which said diaphragm is freely open to the outer air, a sound-amplifying member mounted on said base and acoustically disconnected from said cone diaphragm, a small diaphragm carried by said base and acoustically connected with said amplifying member, and electric mechanism for operating said dia-phragms.

28. In a loudspeaker, the combination of a hollow base having an opening at the top and being provided with lateral sound passages, a large diaphragm enclosed in said hollow base and freely open to the outer air through said passages, a casing adapted to fit into said top opening of the base, means for securing said casing on said base, a small diaphragm mounted in said casing, a horn connected to said casing for amplifying the vibrations of said small diaphragm, and electric mechanism arranged between said diaphragms for operating the same.

29. In a loudspeaker, the combination of i a hollow base having an opening at the top and being provided with lateral sound passages, a large diaphragm enclosed in said hollow base and freely open to the outer air through said passages, a casing adapted to fit intosaid top opening of the base, means for securing said casing on said base, a small diaphragm mounted in said casing,a horn connected to said casing for amplifying the vibrations ofsaid small diaphragm, and electric mechanism carried by said casing for operating said diaphragms.

30. A combined horn and cone speaker comprising a direct-acting cone diaphragm and a small diaphragm amplifying through a horn, means for mounting said diaphragms in fixed spaced relation, electromagnetic mechanism for simultaneously operating said diaphragms, and means for regulating the loudness of said diaphragms independently of each other, said regulating means permitting either diaphragm to be cut out of operation. V

31. A combined horn andcone speaker having electromagnetic mechanism for simultaneously operating the cone diaphragm and the horn diaphragm, means for supporting said diaphragms in fixed spaced relation and manually adjustable magnetic means associated with said mechanism for regulating the volume of reproduction separately for each diaphragm.

32. A loudspeaker having a circular hollow base sloping downwardly from the center toward the periphery, said base forming a chamber freely open to the outer air, a direct-acting cone diaphragm supported horizontally in said base chamber with its apex pointing upwardly, and electromagnetic mechanism carried by the base above said diaphragm for operating the same.

33. A combined horn and cone speaker comprising a small diaphragm and a cone diaphragm supported in concentric spaced relation, a horn acoustically connected withsaid small diaphragm, said cone diaphragm being acoustically disconnected from said horn and directly open to the outer air, and electromagnetic mechanism mounted between said diaphragms for actuating the same independently of each other.

34. A loudspeaker having a hollow casing which constitutes a supporting base, a pair of diaphragms mounted in said casing, said diaphragms having ditferent acoustic prop erties, electromagnetic mechanism in said casing for simultaneously operating said diaphragms independently of each other, electric means in said casing for controlling the quality of reproduction of each diaphragm independently of the other diaphragm, means associated with said mechanism for'regulating the volume of each diaphragm independently offthe other diaphragm, and a plurality of hand-operable connections projecting from said casing for operating said quality-controlling means and said volumecontrolling means independently for each diaphragm.

35. As a unitary construction, a combined horn and cone speaker comprising a directacting cone diaphragm'and a small diaphragm amplifying through a horn, means for mounting said diaphragms in concentric spaced relation, the small diaphragm being arranged above the cone diaphragm, means for acoustically separating said diaphragms, and electromagnetic mechanism arranged between 'said diaphragms for operating the same.

36. A combined horn and cone speaker comprisinga horn supported in vertical position, a small diaphragm at the inner end of said horn, a loudspeaking cone diaphragm supported below said horn in substantially concentric relation to said small diaphragm, said cone diaphragm being acoustically dis: connected from the inner end of said horn and freely open to the outer air, and electromagnetic mechanism mounted between said diaphragms for operating-the same.

37. A combined horn and cone speaker comprising a substantially conical'casing flaring outwardly toward the bottom, a cone diaphragm at the lower end of said casing and freely exposed to the outer air, a horn mounted above said casing in substantially concentric relation to said cone diaphragm, a small diaphragm communicating with the inner end of said horn, said cone diaphragm being acoustically disconnected from said horn, and electromagnetic mechanism arranged between said diaphragms for operating the same.

38; A combined horn and cone speaker comprising a substantially conical casing flaring outwardly toward the bottom, a cylindrical housing mounted on top of said casing and projecting above the same,'sa1d housing containing a diaphragm and electromagnetic actuating means therefor, a horn mounted over said casing and connected at its inner end with said diaphragm, a loudspeaking cone diaphragm at the flaring lower end of said casing and freely exposed to the outer air, said two diaphragms being'arranged in substantially concentric relation, and an electromagnetic unit insaid casing below said housing for operating said cone diaphragm, said cylindrical housing having a bottom wall or plate which separates the two diaphragms acoustically from each other. 39. In a loud speaker, a compound unit having parts for translating sound waves of different tone qualities, one of the said parts having a metal diaphragm, the other of the parts having an armature, a permanent magnet for' producing a field of force in the metal diaphragm and in the armature, and a megaphonic means for amplifying the sound produced by the diaphragm and the armature.

40. In a loud speaker, a permanent magnet, two pole pieces operatively connected to each pole of the magnet, one pair of pole pieces terminating on one side of the magnet, the other pair of pole' pieces terminating toward the other side of the magnet, an armature adjustably positioned in relation to one pair of pole pieces, an armature forming diaphragm positioned in relation to the other pair of pole pieces, electromagnetic coils associated with the pole pieces adapted to vary the magnet influence of the pole pieces on the armature and on the diaphragm to cause the armature and the diaphragm to vibrate, and means to amplify the vibration of the armature and the diaphragm into audible sound waves.

41. In a loud speaker, a compound mag netic unit comprising a permanent magnet, two pairs of pole pieces secured to the poles of the magnet and protruding from opposite sides of the magnet, coils located on on the said pole pieces, a metal diaphragm located in operative relation to one pair of the pole pieces, an armature located in operative relation to the other pair of pole pieces, a horn located in operative relation with respect to the metal diaphragm and a flexible diaphragm mechanically connected to the armature.

42. A cone loudspeaker comprising a horizontal base, a cone diaphragm mounted horizontally on said base with its apex pointing upward, said diaphragm being directly open to the outer air, a frame above said base and diaphragm, and an electromagnetic driving unit for said diaphragm secured to said frame. V

43. In loud speaker mechanism, the combination of a substantially horizontal supporting frame comprising an upper member and a lower base member, a: cone diaphragm mounted horizontally between said members with its apex pointing upward, said diaphragm being directly open to the outer air, and an electromagnetic device attached to said upper member for operating said diaphragm.

44. A loudspeaker comprising a top member and a. base member arranged to form a housing open' tothe outer air, a cone diaphragm supported horizontally in said housmg, and electromagnetic mechanism depending from said top member for operating said diaphragm.

45. 'In loudspeaker mechanism, the combination of a substantially horizontal supporting frame comprising an'upper member and 5 a lower base member, a cone diaphragm mounted horizontally between said members and directly open to the outer air, and an electromagnetic device attached to said upper member for operatin said dia hragm.

' 46. In a loudspea er, a hollow structure provided with sound openings, a cone diaphragm horizontally supported in said structure, a sounding board mounted in said structure below said diaphragm, said board also forming a closure for the bottom of said structure, and electromagnetic mechanism mounted in said structure above said diaphragm for operatin the same.

47. A loudspeaker avin at least tw' -!iaphragms mounted in space relation, e trio mechanism mounted between said diaphragms for simultaneously 0 crating the same, and. manually controllab e means for regulating the loudness of the two diaphragms independently of each other, said -means permittmgeach diaphragm to be out out of operation.

48. A loudspeaker comprising a top memher and a base member arranged to form a housing open to the outer air, a cone diaphragm supported horizontally in-said housing, electromagnetic mechanism secured to 7 one of said members for operatin said diaphragm, and manually adjusta 1e means carried by said housing for re lating the operation of said dia ragm rom outside the housing.

ADOLPH A. THOMAS.