US2815087A

US2815087A - Speaker cabinet

Info

Publication number: US2815087A
Application number: US493764A
Authority: US
Inventors: Delort Rene
Original assignee: Individual
Current assignee: Individual
Priority date: 1955-03-11
Filing date: 1955-03-11
Publication date: 1957-12-03
Anticipated expiration: 1974-12-03

Description

Dec. 3, 1957 Filed March 11, 1955 R. DELORT SPEAKER CABINET 5 Sheets-Sheet l //////l//// /////l//Y/ l /////Y///////|///////l/N INVENTOR ll REANE DELoRr ATTORNEY Dec. `3, 1957 R. DELol-r '2,815,087

SPEAKER CABINET Filed March 11, 1955 s sheets-sheet 2 53 "+5 41 s 52 l5F 34, /37

ATTORNEY Dec. 3, 1957 R. DELORT 2,315,037

SPEAKER CABINET Filed March 11. 1955 5 Sheets-Sheet 3 ATTORNEY nited States Patent() SPEAKER CABINET Rene Delort, Bethesda, Md. Applies-'tion Mareuil, 195s, Serial No. 493,764

7 claims; (cl. 181-31) The'pr'sent invention relates to a cabinet, and more particularly to aV high-fidelity eabinet or enclosure for ldsp'eake'rs v Accordingly, it is an object of the present invention to prot/'idea cabinet or enclosure for speakers which propagates th'esound produced by the speakers an effective manner and reproduces the saine faithfully.l

It isfother object of the present invention to provide a cabinet or enclosure" for a loudspeaker system which provides' high-delity-in the reproduction of the sounds produced lby the speaker for the lower spectrum of the ti'dible range.

Av sti-llftitlier object of the present invention resides in the provision of a speaker cabinet which reproduces faitli'fiilly the-sounds produced by thespeaker by means of an exponential horn having sound paths of various lengths'vvhicli is' exponential in every plane, and which is relatively longby reason of "subtending an angle` of approximately 90 degrees.

A still further bjectof the"'presentl invention resides in the' act-that the" speaker is mounted' in a substantially vertical position", i. e., with the` aXis thereof substantially vertical, and in conducting thesoufnd produced by the thus-Insulated speaker toA the' outside df the cabinet by I'nea'lisV 'of an'exponential horn having sound pathsl of various lengths which Sbtiids an angle f about 90 degrees. A s

It' a' stillfr'the'r object of thepresentinvention to provide a` speaker cabinet fof r al loudspeaker which is mounted; with the axis thereof. substantially vertical, and provides eici'e'nt front and" backloading of -the speaker: y

Another object of thev present invention resides in the provision of a truly exponential horn of substantial length for lpl'l'ijposes of fr'ont l'oadingof ay speaker',.whereby theA spacefo'tm'ed between the sidewalls of the exponential horn 'and' the side` walls' of' the cabinet are used for p'urixise's`r of providin'gback loading spaces for back loading" th'espeakei, apertures being provided for such back loading in the side walls of the cabinet to conductlk the sound waves to the out-side of the cabinet.

Another object ofthe. present invention-is the provision of a speaker cabinetl which is relatively inexpensive" to makeand which .provides a faithful, high-fidelity reproduction ofthe sounds produced` by the" speaker.

A'- still further object of the' present' invention is' the provision of aspeaker cabihetfo socalled highiidelity` reproduction'- systems; which relatively inexpensive to manufactureand which lends itselfy to" mass production bymoliinglthevarious*parts thereof.

Another object of the present invention is thep'rovision ofi-a speaker'cabinet'havingareasonablesize, which, however, does not depend in its use on acorrier, for example, one: fornied by the v'fa'lls of' the rooni Another' ob'j 'ofthe-presentinvention isthe provision of.alspeakerf'cabinetlwlichsis simple in design and con-Y 2,815,087 A Patented Dec. 3, 1957 2, sequently relatively inexpensive in manufacture and mounting. l v

A still further object of the present invention is the provision of a speaker cabinet for high-fidelity reproduction systems which assures proper front and back loading of the speaker in order to insure proper control of the cone assembly whenever it travels to and fro during each cycle, and wherein the front loading is accomplishedby a true exponential horn which is as long as possible while simultaneously eliminating any narrow slots or contractions in the passages for the sound which are undesirable during' the occurrence of strong transients, so as to assure an air loading of the speaker which is as uniform as possible.

A still further object of the present invention resides in the provisionrof a favorable front and back loading of a speaker which does notre'ly on multiple folds or banles which pr'oduce undesirable results when strong transients occur.

Another ob'ject of the present invention resides in the provision of a speaker cabinet with a construction of a fro'nt exponential horn capable of providing runiform loading at all frequencies included between the lowest audibletpdint and the point of the electrical cross-over network with which the speaker or driver is connected.

These andfurther objects, features, and advantages of the present invention will become more obvious from th'e following-description, when taken in connection with thev accompanying drawing which shows, for purposes of illustration only, several preferred embodiments in ac# cordance with the present invention, and wherein:

Figure 1 is a front View showing a' speaker cabinet inv accordance with the present invention in which the high-frequency driver openings are indicated in dashed unes, v y

FignregZ is a cross-sectional view taken along lines z-z of Figure-1, k l

Figure 3 Ais a cross-sectional' View taken along lines 3-3 of they speaker in accordance with the present invention shown in Figure 1,

Figure' 4 is a front view of a modified embodiment of a speaker cabinet in accordance with the present invention',

Figure 5 Ai's a cross-sectional view taken along lines SLS @Figure 4, v

Figure' 6 isA a crosssecti'onal view taken along lines 62-6 Figure 7 is" azcro'ss-section`al view similar toY Figurev 5` showing still a further rnodica'tion of a speaker cabinet in accordance with the present invention.

Figure l8 is a cross-'sectional view taken along lines sr-s' of Figure 1',

Figure 9 is a vcross-sectional view taken along lines 9 9 of Figure 4, and

, Figfre l0` is a cross-sectional view taken along lines 10i-10 of Figure 7.

With increasing awareness of the public of the de'- sirabilityyof faithful reproduction of sounds producedV by lc'nidspeakers, high-fidelity systems are becoming more' and more widespread, and theA demand for high-fidelity' systems has increased sharply.

Various systems havebeen devised previously in which speaken cabinets, which form an important part of the highdidelity' systems have been designed and which utilize corners formed either by the cabinet itself or by asians? plates so as to keep the overall dimensions of the speaker cabinet within certain limitations While providing the equivalent of a good base reflex cabinet of eight or nine cubic feet. However, such multiple bathe-plate speaker cabinets exhibit undesirable characteristics during strong transients.

The present invention provides a speaker cabinet which obviates all the aforementioned disadvantages, and, at the same time, otfers a high-fidelity reproduction of the sounds produced by the speaker while simultaneously providing very etiicient back loading for reinforcing the very low frequencies without the use of any corners.

The present invention may be briefly summarized by stating that the speaker cabinet includes a baille plate or the like in the upper part thereof for mounting the low frequency speaker with the axis thereof substantially vertical, a truly exponential horn subtending an angle of at least 90 degrees and having variable length for conducting the sounds produced at the throat by the speaker to the mouth thereof, thereby providing eiiicient front loading, and utilizing the space formed between the side panels of the exponential horn and the side walls of the cabinet having apertures to effect appropriate back loading of the speaker.

Referring now more particularly to the drawing wherein like reference numerals are used throughout the various views to designate like parts, and more particularly to Figure l, reference numerals 11 and 12 designate the side walls of the speaker cabinet, which are each provided, in the lower portion thereof, with

apertures

13 and 14. The apertures 13 and 14E- may be of any appropriate size and shape, and may be adjustable, if so desired. However, for ease of manufacture they have been illustrated as substantially rectangular, although this particular shape is not intended to be limitative.

The top of the cabinet is enclosed by a top wall 15, and the bottom of the cabinet by a bottom wall 16. The cabinet may be provided with feet or a pedestal 17 so as to provide a clearance between the bottom Wall 16 and the floor. If feet of suicient height are used instead of the pedestal, then apertures 13 and 14 in the side walls 11 and 12 may be omitted and be replaced by the two triangular openings formed at the bottom of the cabinet.

A substantially trapezoidal panel 1S constituting the speaker baille is provided in the upper portion of the speaker cabinet, and is provided with a suitable aperture 19 (Figure 3) over which the speaker 20 is mounted in any suitable manner. The panel 18 is secured to the partition walls of the cabinet, namely, the partition walls 26' and 27 and the rear wall 21 in any conventional manner, as by means of screws, gluing, brackets, supports or the like. The speaker is of the type which reproduces the sounds included between the lowest audible point and the point of the electrical cross-over network, with which it is connected, whereby the cross-over frequency depends on the particular type of the high-frequency speakers or drivers used in connection with the system.

Front loading of the speaker is obtained by means of a truly exponential horn which consists of a rear panel which subtends an angle or arc of approximately 90 degrees (Figure 2) and which is exponentially shaped in a plane substantially parallel to the plane of the side Walls 11 and 12, as shown in Figure 2. The exponential horn is further formed by two

side Walls

26 and 27 which intersect the rear panel 25 along a substantially

exponential line

28 and 29 respectively. It should be noted that the

side panels

26 and 27 of the exponential horn are also substantially exponentially shaped in the horizontal plane, as indicated in Figure 3 in which this shape is indicated partially in full and partially in broken lines.

In order to further increase the exponential characteristic of the front horn, a deflecting member 3@ is provided directly below the panel 18 to which it is fastened in any suitable manner, and includes exponential outer surfaces 31 and 32.

lt should be noted that applicant thus provides a truly exponential front loading horn providing sound paths of various lengths from throat 33 thereof to the mouth 33 due to the degree curvature of this horn, thereby enabling a uniform dispersion of the sound Waves at all frequencies in the lower part of the audible spectrum.

he space 34 provided between the speaker bafe 18 and the top panel 15 constitutes the compression chamber of the speaker cabinet. The compression chamber 34 is in communication with the outside through the

back loading spaces

35 and 36 and the

apertures

13 and 14 respectively. Thus the back-loading horns are formed by the spaces between the outer surfaces of each of the partition panels 26' and 27 and by the side walls 12 and 11 and a portion of rear wall 21 respectively. The

apertures

13 and 14 thus constitute the openings into the atmosphere for the back-loading horns.

Reference numeral 37 indicates padding of any suitable material to avoid any sharp corners or spaces and to thereby enhance the back loading effect and to improve the non-resonant characteristic of the back-loading horn.

The flow direction of sound waves through the frontloading horn is designated by arrows a and through the back-loading horn by arrows b.

The compression chamber 34 is also large enough to accommodate the high-frequency drivers shown in Figure 3 and designated by reference numerals 39 and 4). Figure 3 shows high-frequency drivers of the compression type, although other high-frequency drivers may be used, as will become more obvious from a description of the embodiment of Figures 4 to 6.

The high-

frequency drivers

39 and 40 may be suitably mounted on a front baiiie plate 41.

The course of sound emitted from the high-frequency drivers from the compression chamber is Shown by arrows designated c (Figure 3) and c (Figure 6).

Figures 4 to 6 show a modified embodiment of the speaker cabinet of Figures 1 to 3, wherein substantially rectilinear surfaces are used to approximate the low frequency true exponential horn of Figures 1 to 3, and wherein high-frequency drivers of the cone type are used.

Reference numerals 11 and 12 again designate the side walls provided with

apertures

13 and 14. The top wall is designated by reference numeral 15 while the bottom wall is designated by reference numeral 16. Reference numeral 17 again designates the pedestal of the speaker cabinet. The low-frequency speaker baffle is again designated by reference numeral 18, and is provided with an aperture 19 over which the low-frequency driver 20 is placed and secured in any conventional manner.

The front loading horn is provided with a rear panel 25', and is also constituted by the two

side panels

26 and 27, the lines of

intersections

28 and 29 between the rear panel 25 and the side panels 26 .and 27' being substantially rectilinear. However, it should be noted that these lines of intersection approximate an exponential curve.

The upper deflector 30' consists of two rectilinear outer surfaces 31 and 32', again approximating the exponential shape shown in Figure 2 in connection with the deflector 30.

The compression chamber 34 is again formed between the baille 18 and the top Wall 15, while the

spaces

35 and 36 forming the back-loading horns are again provided between the side panels 26 and 27', the side walls 12 and 11 and a portion of the rear wall 21, thereby providing back-loading horns establishing a communication between the compression chamber 34 and the atmosphere through

apertures

13 and 14.

Appropriate padding is again provided as shown by reference numeral 37.

The high-

frequency speakers

45, 46, and 47 are mounted on the battle wall 41 in any suitable manner, whereby the high-frequency driver 45 may be used in connection with the intermediate frequency spectrum whereas the fastener? high frequency drivers` 46 and 47 located on both sides thereof may be used with the very high frequency spectrum. Since thehigh-frequency drivers are of the cone type, it is preferable to isolate the chamber for the highfrequency drivers fromthe compression chamber 34 by means of a separating'wall 51 whichextends over the entire width `of the cabinet between thetwo side walls 11 and 12 as shown in Figure 6.

The

ports

52 and 53 provided'in the front bafle wall 41 represent ports of a base'reilex arrangement for the high-frequency drivers.

It is understood,however, that compression type highfrequency drivers may be used in the embodiment of Figures 4 to 6, in Vwhichcase no vseparating wall 51 is required, while the ports 52 and53also become unnecessary.

In the embodiment of Figure 7, a further renement of the-embodiment according to Figures 4 to 6 is shown whereby through further rectilinear surfaces a closer approach to the true exponential shape of the horn in accordance with the embodiment of Figures l to 3 is achieved.

In Figure 7, the rear panel or 'wall' of the exponential horn is formed by'panels 25a, 25h and 25e and the two sidepanels, of 'Which-only onev is show-n, by reference numeral 26". The rear panels 2519 and'2'5fc intersect the side panels along the

lines

28 and 28 and the

lines

29 and 29"'L The deector 30 consists of outerY surfaces 55, 56, `57, 58, and 59, all of which are rectilinear, while at the same time more closely approximating' the truly exponential-shape of the deflector 30 of Figure 2.

The various parts of the speaker cabinet may be made of any suitable material, such as, for example, wood, Celotex, moldedplastics, or the like.

Thus, the present invention discloses a. speaker cabinet, which, in Figures l to 3, utilizes a true front exponential horn in all planes, i. e., in the horizontal as well as vertical planes, while the embodiments, according to Figures 4 to 7, show a horn which approximates the exponential shape.

Moreover, the structure in :accordance with the present invention provides in all embodiments thereof an effective front l-oading, by reason of the use of an unusually long front horn which is essentially exponential in shape, and made possible Iby the particular mounting of the speaker so that the horn subtends an raro over 90 degrees, the variable exponential horn with walls of unequal lengths being very effective for a reproduction of sounds over a very wide frequency range.

Furthermore, the use of a 90 degree curved horn, together with the particular mounting of the speaker with the axis thereof substantially vertical, provide automatically sound paths of various length through the exponential horn .for purposes of front loading.

Moreover, the present invention provides a very effective back loading by utilizing effectively the space available between the cabinet walls fand the exponential horn, which back loading prevents standing reverberating or resonance waves in a transverse plane due to the t-riangular shape of the back-loading horn, while at the same time effectively eliminating all dead cavities inherent to any corner back-loading arrangement, such as, for example, provided Iby the walls of the house itself.

In summary, among others, the following advantages are derived by the present invention:

A longer front horn than is obtainable with a straight horn when the speaker is mounted with the axis thereof in the horizontal position while, at the same time, keeping the overall enclosure within reasonable proportions.

A true front exponential horn, or an approximately true exponential horn, providing sound paths of various lengths from the throat to the mouth thereof due to the 9Q- degree curvature of the horn thereby enabling a uniform dispersion of the sound waves at all-frequencies of the lower part of the spectrum.

Avoidance of all dead cavities inherent in some corner back loading arrangement.

A triangularly shaped back-loaded horn to prevent standing waves in the transverse plane.

A very eicient back loading for the reinforcement of the very low frequencies without the use of corners.

A `simple mounting of the horn.

An ideal motion of the voice coil and cone assembly of the speake-r along the axis of gravity thereof.

Ample space in the -upper chamber to permit `the mounting of Iany combination of medium or high-frequency drivers either of the compression type or the cone type Suppression of the point effect due to the large mouth offered to the dispersion of the low frequencies and their indirect radiations, and 'also due to the entire separation of the high frequencies from those of the low frequency spectrum.

While I have shown several preferred embodiments in accordance with the present invention, it is understood that the same is susceptible of many modifications within the scope of a person skilled in the art, and I intend to cover any such modifications, except as limited by the appended claims.

For example, the speaker cabinets of the embodiments of Figures 4 through 7 may be provided with lan exponential rear panel 2'5 while retaining the side panels 26( and 27', or the speaker cabinet in .accordance with Figures 1 to 3` may be provided with a rear panel, such as the rear panel 25 `or 2S of the other modifications.

Furthermore, it is understood that the front of the speaker cabinet may be enclosed in any suitable manner, as, for' example, by means of cloth which may be secured toA the speaker cabinet in any conventional manner.

I claim:

1. A high-fidelity speaker cabinet comprising two side walls, a back wall and a front wall connecting said side walls and a top wall enclosing the top of said cabinet, means for mounting the speaker in the upper part of said cabinet with the axis thereof substantially vertical, and exponential horn means subtending an angle of approximately degrees in a plane parallel to one of said side walls for conducting the sounds produced by said speaker :from the throat thereof to the outside of said cabinet through the mouth of said horn means, the axis of the throat of said horn means being essentially vertical and the axis of the mouth of said horn means being essentially perpendicular to said back wall.

2. A high-fidelity speaker cabinet comprising two side walls, a back wall connecting said side walls and a top Wall enclosing the top of said cabinet, means for mounting the speaker in the upper part of said cabinet with the axis thereof substantially vertical, and exponential horn means having an exponential shape in planes parallel and perpendicular respectively to said side walls subtending an angle of approximately 90 degrees for conducting the sounds produced by said speaker from the throat of said horn means to the outside of said cabinet through the mouth of said horn means, said horn means being also substantially exponential in shape in a horizontal plane 4and the throat of said horn means having .an essentially vertical axis While the mouth of said horn means terminates directly in a plane parallel to said back wall.

3. A high-fidelity speaker cabinet comprising two side walls, a back wall connecting said side Walls and a top wall enclosing the top -of said cabinet, means for mounting the speaker in the upper part of said cabinet with the axis thereof substantially vertical, and exponential horn means subtending an angle of approximately 90 degrees for conducting the sounds produced by said speaker to the outside of said cabinet through the front thereof, said exponential horn means being exponentially shaped in all planes and including a -rear panel having an essentially exponentially shaped contour in a plane substantially parallel to one of said side walls, and two side panels one on each side of said rear panel essentially exponentially shaped in planes parallel to said rear wall and to said top wall, respectively, the lines of intersection of said side panels and said rear panel being essentially exponentially shaped.

4. A high-fidelity speaker cabinet `comprising two side walls provided with apertures, a back wall connecting said side walls and a top wall enclosing the top of said cabinet, means for mounting the speaker in the upper part of said cabinet with the axis thereof substantially vertical, exponential horn means subtending an angle of approximately 90 degrees for front loading said speaker by conducting the sounds produced by said speaker from the throat of said horn means to the outside of said cabinet through the mouth thereof, said exponential horn means being of approximately exponentially shaped contour in a plane substantially parallel to one of said side walls and including 1a rear panel and two side panels one on each side of said rear panel essentially exponentially shaped in a plane parallel to said rear panel, the lines of intersection of said side panels and said rear panel being essentially exponentially shaped, and means including the space formed between the outer surfaces of said side panels, said side walls and said back wall for back-loading said speaker, said last-named means including said apertures.

5. A highdelity speaker cabinet comprising two side walls, a back wall connecting said side Walls and a top wall enclosing the top of said cabinet, means for mounting the speaker in the upper part of said cabinet with the axis thereof substantially vertical, approximately exponential horn means with the axis thereof subtending an angle of CIK approximately 90 degrees in a plane parallel to one of said side walls for front loading said speaker to conduct the sounds produced by said speaker to the outside of said cabinet, said exponential horn means having a deector and a 4rear panel, said rear panel being considerably longer than said dellector, and means formed between said walls and the outer surfaces of said irst-mentioned horn means for back loading said speaker.

6. A high-fidelity speaker cabinet comprising two side walls, a back Wall connecting said side walls and a top wall enclosing the top of said cabinet, approximately exponential horn means with `an essentially vertical throat and a mouth terminating in a plane parallel to said back Wall, the axis of said horn means subtending an angle of approximately 90 degrees in a plane parallel to one of said side walls for conducting the sounds produced by said speaker from said throat to the outside of said cabinet through the mouth thereof, and means formed at least in part by the walls of said cabinet and substantially triangularly shaped in a plane parallel to said top wall -for back loading said speaker.

7. A speaker ycabinet according to claim 6, wherein said second-mentioned means is formed by the spaces between the outer surfaces of said first-mentioned horn means and said back and Side walls of said cabinet.

References Cited in the lile of this patent UNITED STATES PATENTS Roberts May 30, 1939 Olson Dec. 17, 1940 Gassan, publication in Audio Engineering, pages 22, 23, 63 and 64, September 1953.