US2193399A - Acoustical apparatus - Google Patents

Description

A. W. FISHER ACOUSTICAL APPARATUS Filed March 3, '1939 March 12, 1940.

I)" flIMIMIIIIIII//II/WWW/IIIMM/I/WIIII/IIIIIII v Patented Mar. 12, 1940 2,193,399

UNITED STATES PATENT OFFICE ACOUSTICAL APPARATUS AlianW. Fisher, St. Petersburg, Fla. Application March 3; 1939, Serial No. 259,640

8 Claims. (Cl. 181-431) This invention relates to acoustical apparatus Referring to the drawing, cabinet it is arand more particularly to a loud speaker arrangeranged to .house a sound reproducing apparatus ment in connection with sound? reproduction. in the upper portion thereof which may take the This application. is a continuation in part of form of a radio set it having a volume control a pending application Serial No. 179,373, filed Deand a switch lrnob I2, a tuning control knob cember 11, 1937. tuning dial it and resonance control knob it.

Acoustical devices for the reproduction of sound in the lower portion of the cabinet iii an inand loud speakers in use today fail to present clined main sounding board it, which may be proper tonal efiects in that essential resonating fabricated of wood or other suitable material,

features have not been incorporated in their deis supported along its peripheral margins P in 1 sign. Previous to my invention, manufacturers a manner to permit free vibration throughout its have been reluctant to provide proper resonating width and length. Similarly supported along its means, Dames, sounding board, and dare mernperipheral margins P a speaker mounting and hers because of lack of space in a cabinet of reaauxiliary board A are arranged in spaced paralsonable size with known arrangements of parts. lei relation to the main sounding board iii. This Most manufacturers of radio sets today are so auxiliary board A may be fabricated of onedesigning their speakers in relation to the requarter inch fiber board or other suitable roa=- mainder of the apparatus that when sound eznaterial of corresponding dimension. Though the hates therefrom a more or less objectionable parts may be manufactured in any size, when the resonance tones accompany the sound reproducmain sounding board it is approximately twen-= 20 tion. These resonance tones are sometimes unty-four inches square a spacing of from approxipleasant, distasteful, and it may be desirable to mately one-hall to one inch, preferably threevary or eliminate the same. quarters inch, is utilized between the main sound= It is an object of the invention to provide a ing board it and the auxiliary board A. A flare loud speaker apparatus, having pleasing tonal member it, which may take the form of a hollow 25 qualities and resonating features, of compact -irustratad cone, is secured to the rear portion of form, the auxiliary board A and the peripheral margin It is a further object of the invention to pro- M of the outlet of the speaker 91 which may be vide sound reproducing apparatus including a of a conventional type is also secured and supsounding board having a relatively great freely ported by the said auxiliary board. 3' vibrating area. The main sounding board it has arranged It is a still iurther object of the invention to thereon and therethro-ugh a desired number of provide sound reproducing apparatus with an arresonating tubes iii mounted in rubber or other rangement whereby more or less objectionable resilient bands or sleeves R at their bases. In

resonance tones accompanying the sound reproi a plurality of resonating tubes is are il- 85 duction may be controlled by the listener or lustrated, which tubes attribute to the device operator. proper pleasing tonal effects. This group of Other objects and the nature and advantages of tubes 98 cover a diatonic range of two octaves. the invention will be apparent from the follow- The tubes l9 are arranged on the main sounding 4o ing description taken in conjunction with the board 66 in a manner such that their axes are accompanying drawing, wherein: substantially perpendicular to the sounding board Fig. 1 is a front elevation of sound reproducand in alignment with the loud speaker H, the tion apparatus with parts cut away disclosing axis of which is also substantially perpendicular portions of a loud speaker arrangement, in acto the main sounding board. The tubes 59 are cordance with the present invention. further arranged in a manner such that their 4:5

Fig. 2 is a section taken along line 2-2 of Fig. front races 28 lie in a plane substantially parallel l and looking in the direction of the arrows. to the front of the cabinet and intersect said Fig. 3 is a fragmentary section taken alon plane to form ellipses, as shown in Fig. 1. In line 3-3 of Fig. 2 looking in the direction of the effecting this arrangement the shorter tubes are arrows, disclosing the mechanism for controlling placed in the bottom of the main soundin ard 5 the resonance qualities of the apparatus. 5 6 which is inclined in a manner whereby its hot- Fig. 4 is an enlarged detail sectional view iltorn portion is relatively close to the front of lustrating the valve arrangement on the speaker the cabinet, its top portion is relatively remote mounting or auxiliary sounding board and its from the front of the cabinet and the succeeding 65 relation to the main sounding board. longer tubes are arranged higher up on the main sounding board l6, as illustrated in the drawing.

In addition to the tubes is that transmit the tone from the front of the speaker, another set of tubes 2i may be arranged in circular form about the tubes l8 and through the main sounding board E5 in communication with the space between flare member l8 and housing 22 which envelops speaker I? but is arranged in spaced relation thereto. and secured to the rear side of auxiliary board'A in a manner to cooperate with the rear portions of the tubes 2! whereby they may carry sound that originates from the rear of the speaker which involves more or less objectionabie resonance tones. The resonating tubes is"; cooperate with the set of tubes 2!! to boost or convert the tonal range to one that is chromatic having half tones throughout. Thus, it will be seen that the tubes 2i act in a sense as booster tubes for the sound that ordinarily emanates from the rear portion of the speaker, when projected forward and mixed with the main speaker output, loses its objectionable qualities and becomes a valuable asset. The housing 22 may or may not be fabricated of sound deadening material, such as felt paper, for example.

In practice I have found that the sound that emanates from the speaker is weaker at or near its circumference and to compensate for this weakness tubes 2! have been provided to bring additional volume from the rear of the speaker which more or less equalizes the sound emanating from substantially the entire area of the sounding board. Should this added sound be too great for the room or listener, I may provide a control, comprising knob l5 cooperatively associated with shaft 23 in a manner whereby through worm and gear mechanism 24, the shaft 25 may rotate pulley 26 winding thereon wire Z'l which is attached to rotate at annular disc 28, at car 29, causing said annular disc to rotate in the direction of the arrow as shown in Fig. 3. Tending to pull rotating annular disc back to its original position is spring 30 fixed to a portion of the cabinet by hook 3! at one end and at its other end fastened to wire 32 which engages car 33 of the rotating disc 28. Guide means 34 secured to the front side of auxiliary board A. may be provided in cooperative relation to rotating disc 28 whereby circular openings 35, arranged in said annular disc to correspond with the rear openings in tubes 2|, may transmit all, part, or substantially prevent the transmission of sound from the rear of the speaker through tubes H to the listener, depending upon the position of the annular disc 28 which in turn is controlled by the knob l5. The annular disc 28 may be fabricated of one-quarter inch fiber board, or any other suitable material and in corresponding dimension.

On the front of the sounding board encasing the resonating tubes is and tubes 2!, a casing 36 may be provided with a substantially circular cross section at its base 31, and an inwardly curved portion at its front end 38. The casing 36 may be fabricated or" a sound deadening material such as paper or the like. With this arrangement sound emanating from the resonating tubes will lie-concentrated and prevented from spreading over a wide area thereby giving warmth to the sound reproduction which is noticeably pleasant. The casing 36 is similar in design to the shape formed by a singers lips to concentrate the sound emanating from his mouth and which gives a mellow effect thereto.

The tubes 2| arranged about the resonating tubes l9, may be considered as Semi-tones from a voicing angle, and in combination with the tubes I 9 form a chromatic scale of tones, one-half tones from bottom to top, which adapt themselves to those emanating from speaker l'l, so that regardless of the position of the disc 28 or the use of same to moderate the volume of tone which originates from the rear of the speaker, all sound, light or strong, goes through tubes M. The use of speaker mounting and sounding board in conjunction with the tubes 2| prevents the elimination ,of tones emanating from the peripheral regions of the speaker which not only have musical value but make more uniform the flow of sound to the listener for they act to boost the power at points remote from the center of the apparatus, which points most need boosting as the speaker like a spot light is more powerful at its center, points remote from the center shading off. Whether the rotating disc 28 is in such position as to effect closing of the openings 35 or not, the sound travels the entire chromatic scale covering better than two octaves and sound above or below adapts itself to these base or fundamental tones.

With the arrangement described, sound may be reproduced in a pleasing and effective manher with the absence of harsh vibrant eifects, with a control of the more or less objectionable resonance tones emanating from the rear of the speaker and in a greater volume without distortion. Frequently, a listener to, or operator of, a radio set, as manufactured today, will be unable to satisfactorily hear the tones of the various instruments of the original composition unless the volume control is turned up to a point where it is no longer pleasing, because of the accompanying excess noise or volume. With my invention, however, it is possible to reduce the size of the speaker proper and still receive the desired tonal effects which makes it feasible to produce a console at lower cost without affecting the quality of reproduction.

It will be obvious to those skilled in the art that various changes may be made in this device Without departing from the spirit of the invention and therefore the invention is not limited to what is shown in the drawing and described in the specification but only as indicated by the appended claims.

I claim:

1. An acoustical device comprising a main sounding board, a plurality of resonating tubes mounted on and through said main sounding board, said main sounding board being supported at its periphery whereby free vibration throughout the major surface of said main sounding board may be effected, an auxiliary board having a first opening therein mounted in spaced relation to said main sounding board, saidauxiliary board being supported at its periphery whereby free vibration throughout its major area may be effected, sound producing means adjacent said opening in said auxiliary board, said auxiliary board having a second opening located in spaced relation to said first opening, a housing cooperating with said auxiliary board to envelop said sound producing means and said first and second openings, a resonating tube mounted on said main sounding board and communicating with said second opening.

2. The structure recited in claim 1, and means for varying the communication between said resonating tube and the opening in the auxiliary board spaced from said sound producing means.

3. An acoustical device of the class described comprising an inclined main sounding board with its upper part tilted rearwardly and its lower part tilted forwardly, an auxiliary board having an opening therein and arranged in spaced relation to said main sounding board, said main sounding board and said auxiliary board being supported at their respective peripheries whereby free vibration throughout their major areas may be effected, sound producing means arranged ,on the rear side of said auxiliary board with the front portion of the sound producing means adjacent said opening therein, resonating tubes arranged on the front side of said main sounding board, said resonating tubes being of varying lengths and having their axes generally normal to the main sounding board. the longer size tubes being arranged above the shorter size tubes,

whereby the front edges thereof lie in a substantially vertical plane and whereby a minimum of space is occupied, said auxiliary board having a second opening therein communicating the back of said sound producing means with a resonating tube arranged on the front side of said main sounding board.

4. The structure recited in claim 3, the bases of said tubes being insulated from said main sounding board by resilient bands.

5. The structure recited in claim 3, and means for varying the area of said second opening to vary the communication between the rear side of said sound producing means and at least one of said resonating tubes.

6. An acoustical device comprising a main sounding board having first and second openings therein, an auxiliary board supported in spaced relation thereto and having a first and second opening therein, said boards being supported at their peripheries to permit free vibration throughout their planular areas, sound producing means having its front side adjacent the first opening in said auxiliary board, the first opening in said main sounding board communicating with the first opening in said auxiliary board, a housing in spaced relation to said sound producing means and cooperating with said auxiliary board to envelop said sound producing means whereby the second opening in said main sounding board and the second opening in said auxiliary board will communicate with the space between the housing and the rear side of said sound producing means.

7. The structure recited in .claim 6, and valve means for varying the communication between the second opening in said main sounding board ALLAN W. FISHER.

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