US2801703A

US2801703A - Diffused-tone cabinet for organs

Info

Publication number: US2801703A
Application number: US401884A
Authority: US
Inventors: Daniel W Martin
Original assignee: BALDWIN PIANO CO
Current assignee: BALDWIN PIANO Co
Priority date: 1954-01-04
Filing date: 1954-01-04
Publication date: 1957-08-06
Anticipated expiration: 1974-08-06

Description

D. w. MARTIN DIFFUsED-TONE CABINET FOR ORGANS iled Jan. 4, 1954 Aug. 6, 1957 ATTCR N EVS.

.F'IGZ INVENTOR.

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United States Patent O DIFFUSED-TONE CABINET FR ORGANS Daniel W. Martin, Newtown, Ohio, assigner to The Baldwin Piano Company, Cincinnati, Ohio, a corporation of Ohio Application January 4, 1954, Serial No. 401,884

8 Claims. (Cl. 181-31) My invention relates to tone cabinets for loudspeaker systems and more particularly to tone cabinets for electronic organs.

Organ tone cabinets in use at the present time are of generally two types. The rst employs direct-radiator loudspeakers directed toward the listening area in the manner of a conventional radio loudspeaker. Although many electric organs employ this type cabinet, the resulting tone is not considered organ-like in that the apparent size of the source is small, the ratio of direct to reflected sound is high, and the sound wave is not diffused as it would be in a pipe organ containing many sound sources separated from each other in space. The other principal type of tone cabinet in present use directs the sound upwardly from the top of the enclosure or downwardly through the enclosure to one or more sound emission openings or ports. Some cabinets of this type employ combinations of speakers arranged to project sound in both directions. While this latter type of cabinet produces diffusion of tone and increases the apparent size of the sound source, it has the disadvantage that many enclosure resonances are introduced, resulting in a very ragged response curve plotted against frequency. In addition, the loudspeakers do not operate as efficiently as they might, and nonlinear distortion is appreciable.

Conventional horn loudspeaker systems, such as are used in theatres and arenas have been tried on electronic organs in many special installations, and their high etiliciency and low distortion have proved desirable in auditoriums, halls and other large rooms having very long reverberation time (four seconds or longer). In smaller rooms where the reverberation time is more normal (about two seconds) or too low for good organ tone (less than two seconds) the conventional horn loudspeaker systems have been found to be generally unsatisfactory because of the highly directional characteristics of such horns. Furthermore, the equipment was either tooffunctional in appearance for its exposed installation in a home or church, or was enclosed in an expensive cabinet intended primarily for decoration and not intrinsically a part of the loudspeaker system.

It is, therefore, a principal object of this invention to provide a compact tone cabinet incorporating a plurality of loudspeakers so arranged and operated that the low frequency range of signal passes to one of the loudspeakers, whereas the high frequency range of signal passes to a second loudspeaker, the speakers being arranged in the cabinet to provide enhancedefliciency and diffuseness of sound.

It is a principal object of my invention to provide a tone cabinet which takes advantage of the high eticiency typical of horn-loaded loudspeakers while at the same time providing for broad, non-directional sound distribution Which is untypical of horns.

Yet a further object of my invention is the provision` of a tone cabinet having smooth response-frequency characteristics untypical of other diffusing organ tone cabi- ICC nets of which I am aware; and which will produce a high ratio of reflected-to-direct sound in spaces of moderate reverberation.

Yet a further object of my invention is the provision of a tone cabinet of pleasing appearance, which also serves functionally as a major part of the horn surface, the construction thereby resulting in reduced cost to manufacture, ease of assembly, and at the same time a rigidity of construction required for good low-frequency response and freedom from rattles in the cabinet.

These and other objects of my invention which will appear hereinafter or which will be apparent to the skilled worker in the art, upon reading these specications, I accomplish by that construction and arrangement of parts of which I shall now describe an exemplary embodiment.

Reference is now made to the accompanying drawings wherein:

Figure l is a plan view with parts broken away of a tone cabinet in accordance with my invention.

Figure 2 is a vertical sectional view taken along the line 2 2 of Figure l.

Figure 3 is a side elevational view of the tone cabinet with parts broken away.

Referring now to the figures of the drawings, I have therein illustrated a cabinet 1 which is rectangular in cross section and closed on its front, rear, end and bottom walls. The top panel Z is open and will be preferably covered with a suitable grille cloth, louvred or otherwise constructed to provide an acoustically transparent cover. Within the cabinet, and utilizing in part the walls of the cabinet, I provide a low-frequency horn 4 extending from the top to and across the botom of the cabinet and having its mouth opening at the top thereof. Opposed sides of the horn are dened by the front and rear walls of the cabinet, while a major portion of a third side thereof is made up of the end wall 5 of the cabinet. The remaining side of the horn is made up of a plurality of panel pieces 6 connecting rigidly the front and rear walls of the cabinet, the panel pieces extending downwardlyv and inwardly from the upper edge of the remaining end wall of the cabinet, in the manner best seen in Figure 2 of the drawings. The lower portion of the horn Comprises a curved neck portion 7 composed of the angularly related panel pieces 8 connecting rigidly the front and rear walls of the cabinet, the neck portion extending vacross the bottom of the cabinet and terminating in an upwardly opening throat 9 underlying the panel pieces 6. A cone-type loudspeaker 10 is connected to the throat 9, the loudspeaker being mounted on a suitable panel 11.

The inclined wall of the horn 4 composed of the

panel pieces

6 and 8 defines a space 12 in which may be provided a suitable bracket means 13 on which may be mounted amplifying means indicated generally at 14. The enclosed space 12 is large enough to prevent acoustical stiffening of the cone of the loudspeaker 10, and will additionally serve to prevent back radiation of the loudspeaker 10 from the cabinet.

A high frequency driver unit 15 is also mounted within the space 12, and the high frequency unit is provided with a at horn 16 arranged to extend upwardly within the mouth of the horn 4. The flat horn 16 has a narrow mouth 17 opening upwardly adjacent the rear wall of the the cabinet. In fact, the rear wall of the cabinet may comprise one wall of the flat horn, the rear wall thus serving as a wall for both the low-frequency horn 4 and the high-frequency horn 16.

In the construction just described, maximum use is made of the side walls of the cabinet in the construction of the

horns

4 and 16. The cross dimension between the opposed walls of the horn 4 (the front and rear walls of the cabinet) does not permit a cross-mode of vibration below 375-400 C. P. S. (cycles per second) where electrical cross-over to the high frequency speaker would be made. The panel pieces 6 and. 8 which form in part the horn 4 act to rigidify the cabinet so that little if any additional bracing is required to prevent panel vibration even at low frequencies.

The very narrow slot-like mouth of the at horn 16 produces a very broad directional characteristic, thereby combining horn eiciency and broad directivity which produces a desirable balance between direct and gen erally reflected sound.

Both the large horn 4 and the small horn 16 may be constructed entirely of wood. Solid wood can be used for the

panel pieces

6 and 8, or the entire contour-wall can be formed in a laminated curved shape by gluing plies together, as in the curved walls 17 and 18 of the small horn. The construction of all parts is extremely simple, thereby minimizing their cost, and the arrangement of parts in such that they may be easily glued together.

The outer face 19 of the small horn can then be cut to shape from plywood and secured to the sides 17 and 18 by means of screws or the like.

I have also found it desirable to provide an access door 20 in the rear wall of the cabinet by means of which the amplifier 14 and both loudspeaker units may be easily serviced.

By means of my construction I am enabled to take advantage of the increased efficiency of a horn-type speaker and yet minimize the directivity ordinarily encountered in the middle frequency and high frequency range. In addition, this objective is accomplished in a cabinet of a size suitable for home installation.

Modifications may, of course, be made in my invention without departing from t'ne spirit of it.

Having, however, described my invention in an exemplary embodiment, what I claim is new and desire to secure and protect by Letters Patent is:

l. In a tone cabinet for electronic organs and the like, a rectangular cabinet having front, rear and end walls, a top and a bottom, a first horn for low frequency sound production occupying a major portion of the enclosure volume of said cabinet and having its front and rear Walls defined by the front and rear walls of said cabinet, with the mouth of said first horn opening upwardly at the top of said cabinet, said top being `acoustically transparent, and a second horn for high frequency sound production mounted within said cabinet and contained primarily within the body of said first horn, said second horn comprising a flat horn extending lengthwise of said cabinet and having an elongated slot-like mouth opening upwardly at the top of said cabinet.

2. In a tone cabinet for electronic organs and the like, a rectangular cabinet having front, rear and end walls, a top and bottom, a first horn for low frequency sound production occupying a major portion of the enclosure volume of said cabinet and having its front -and rear walls defined by the front and rear walls of the cabinet, the mouth of said first horn opening upwardly at the top of said cabinet, said top being acoustically transparent, and a second horn for high frequency sound production mounted within said cabinet and contained primarily within the body of said first horn, said second horn comprising a flat horn extending lengthwise of said cabinet with its front and rear walls paralleling the front and rear Walls of the cabinet, said second horn having an elongated slot-like mouth opening upwardly at the top of the cabinet in side-by-side relationship to the mouth of said first horn.

3. In a tone cabinet for electronic organs and the like, a rectangular cabinet having front, rear and end walls, a top and a bottom, a first horn for low frequency sound production occupying a major portion of the enclosure volume of said cabinet and having its front and rear walls defined by the front and rear walls of the cabinet, the

` mouth of said first horn opening upwardly at thetop of said cabinet, said top being acoustically transparent, and a second horn for high frequency sound production mounted within said cabinet and contained primarily Within the body of said first horn, said second horn cornprising a at horn extending lengthwise of said cabinet and having its rear wall defined by the rear wall of the cabinet, the front wall of said second horn extending parallel to the rear wall and defining therewith an elongated slot-like mouth extending lengthwise of the cabinet and opening upwardly at the top thereof.

4. The structure claimed in claim 3 wherein said first horn is a folded horn extending downwardly toward and across the bottom of the cabinet from end to end thereof and terminating in an upwardly opening throat.

5. The structure claimed in claim 4 wherein at least one other side of said first horn is dened in part by an end wall of said cabinet, and wherein the remaining side of said rst horn is defined by at least one panel piece extending downwardly and inwardly from the upper edge of the remaining end wall of said cabinet, there being a free space within said cabinet between the said panel piece and the said last-named end wall of the cabinet.

6. The structure claimed in claim 5 wherein a loudspeaker is mounted in said free space covering the throat of said first-named horn.

7. The structure claimed in claim 6 wherein the throat of said second-named horn extends into said free space, and wherein a driver for said second horn is connected to the throat of said second horn in said free space.

8. The structure claimed in claim 7 wherein said free space includes bracket means for mounting an amplifying system for said horns.

References Cited in the file of this patent UNITED STATES PATENTS 1,750,900 Minton et al. Mar. 18, 1930 2,604,182 Massa July 22, 1952 2,643,728 Anthony June 30, 1953