US3608665A

US3608665A - Sound-reproducing structure

Info

Publication number: US3608665A
Application number: US858484A
Authority: US
Inventors: Mohamed B A Drisi
Original assignee: Individual
Current assignee: Individual
Priority date: 1969-09-16
Filing date: 1969-09-16
Publication date: 1971-09-28
Anticipated expiration: 1988-09-28

Abstract

A sound-reproducing structure wherein one or more loudspeakers are mounted on baffle means within a baffle housing to direct the sound (a) from the speaker, directly, forwardly outwardly through the forward opening of the cabinet; (b) against a reflecting surface within the cabinet and hence forwardly outwardly through the forward opening of the cabinet; (c) inwardly against the apex of the baffle means and hence forwardly outwardly through the forward opening of the cabinet. From the back of the cabinet, as a reverse phase, the sound follows a similar reflecting and retarding process but aimed toward the rear of the cabinet. The sound-reproducing structure effectively defines a phase division horn means wherein a portion of the total sound emanating forwardly and rearwardly from the cabinet is delayed in time before passing outwardly therefrom.

Description

United States Patent [72] Inventor Mohamed B. A. Drlsi 100 W. Main St, Glenwood, 111. 60425 [211 App]. No. 858,484

[22] Filed Sept. 16, 1969 [45] Patented Sept. 28, 1971 [54) SOUND-PRODUCING STRUCTURE 8 Claims, 5 Drewlng F19.

[52) us. C1. 181/31 B [51] Int. CL. 10k 13/00, V H04r 1/28 [50] FieldolSearch l81/31.l,

[56] References Cited UNITED STATES PATENTS 1,866,603 7/1932 Schlenker 181/32 1,932,343 10/1933 Holland 181/31 2,038,253 4/1936 Wheeler et al... 181/31 2,816,619 12/1957 Karlson 181/27 2,927,657 3/1960 Patla et a1. 181/31 3,136,383 6/1964 Hopkins 181/31 3,327,044 6/1967 hdarkowitz 84/ 1.01

Primary Examiner-Stephen .l. Tomsky Attorney-Hofgren, Wegner, Allen, Stellman & McCord ABSTRACT: A sound-reproducing structure wherein one or more loudspeakers are mounted on bafile means within a batfle housing to direct the sound (a) from the speaker, directly, forwardly outwardly through the forward opening of the cabinet; (b) against a reflecting surface within the cabinet and hence forwardly outwardly through the forward opening of the cabinet; (c) inwardly against the apex of the bafi'le means and hence forwardly outwardly through the forward opening of the cabinet. From the back of the cabinet, as a reverse phase, the sound follows a similar reflecting and retarding process but aimed toward the rear of the cabinet. The soundreproducing structure effectively defines a phase division horn means wherein a portion of the total sound emanating forwardly and rearwardly from the cabinet is delayed in time before passing outwardly therefrom.

sounn-nnrnonucuvc STRUCTURE BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to sound-reproducing structures and in particular to loudspeaker cabinet structures.

2. Description of the Prior Art One conventional form of sound transducer comprises a loudspeaker defined by a diaphragm which is caused to vibrate in accordance with an audiofrequency electrical signal impressed on a coil mechanically connected to the diaphragm. in the conventional loudspeaker, the diaphragm is frustoconical with the coil being mounted at its apex. Sound is radiated from the diaphragm as the result of the mechanical vibrations induced therein by the electromechanical transducer defined by the coil. The sound is normally propagated forwardly from the inner surface of the frustoconical diaphragm. However, at the same time that a sound wave is generated by the front surface, a reversely out-of-phase sound is generated by the rear surface. To preclude interference between the two reversely out-of-phase sounds, different forms of baffles and housing structures have been developed.

One well-known form of such cabinets comprises a horn wherein the loudspeaker is placed at the apex of an exponentially widening chamber to provide high efiiciency in the radiation of the sound forwardly from the horn. Another form of cabinet structure is one wherein the loudspeaker is carried on a baffle within the cabinet and additional wall means are provided for directing the rearwardly generated sound through a passage and forwardly outwardly through a second opening in the cabinet. The length of the passage within the cabinet is preselected so that sound of a preselected low frequency leaves the second opening substantially in phase directly with the radiated sound delivered from the front surface of the loudspeaker. A further type of sound-reproducing structure utilizing such loudspeakers is that wherein the diaphragm is effectively sealed across the chamber defined by the cabinet while being substantially freely supported with the portion of the chamber within the cabinet behind the loudspeaker diaphragm serving as an air piston means preventing excessive excursions of the diaphragm in producing the sound.

While the known sound-reproducing structures such as those described above produce generally acceptable electromechanical translation of the electrical audio signal, they have serious disadvantages in failing to produce such translation completely faithfully and are relatively costly.

SUMMARY OF THE INVENTION The present invention comprehends an improved sound reproducing structure providing an improved high fidelity electromechanical sound-producing means. The structure effectively defines a type of horn structure wherein the sound generated by the loudspeaker means is delivered forwardly from the cabinet through a widening outlet. However, in the present invention, the loudspeaker means is not disposed at the apex of an outwardly flaring wall means, but rather, is provided in the sidewall thereof at a point spaced forwardly of the apex. Thus, a portion of the sound generated by the loudspeaker is caused to pass forwardly directly outwardly from the structure somewhat in the manner of a conventional horn. At the same time, a portion of the sound is directed against an opposed wall surface to be reflected forwardly outwardly through the forward opening. A third sound may be directed rearwardly through a rear opening of the cabinet or may be suitably absorbed within the cabinet, as desired.

The loudspeaker means may comprise one or more loudspeakers mounted on baffled wall portions. in one highly desirable form, the baffle wall means defines a pyramidal forwardly opening structure with a loudspeaker mounted in each of the faces of the pyramid.

More specifically, the present invention comprehends an improved sound-reproducing structure providing improved high fidelity. It does this by producing wider dispersion of the wise demonstrated when such a loudspeaker is used in conjunction with conventional bafiles. The structure effectively defines a type of horn structure wherein the sound generated by the loudspeaker means is delivered forwardly from the cabinet through a widening outlet. However, in the present invention, the loudspeaker means is not disposed at the apex of an outwardly flaring horn means, rather, is provided in the sidewall thereof at a point spaced either forwardly of the apex or inwardly of the forward opening. Therefore, the soundgenerating surface of each loudspeaker is thereby affected and acted upon, simultaneously by the baffle and the baffle-housing means, which are, actually two opposedly aimed horns. While these horns appear to be different from each other, they are geometrically and acoustically identical. When functioning, each of these opposedly aimed horns couple with one side of the one or more loudspeakers housed within the cabinet. Thus, the sound emanating from the forward side of a loudspeaker is sirnply described as being divided into three portions: (a) one portion of this sound is caused to pass forwardly, directly outwardly from the front of the structure in the manner of a conventional horn; (b) the second portion of the sound is reflected one or more times before it is permitted to escape outwardly; and (c) the third portion of the same sound is directed inwardly against the apex of the horn. This is done directly and through one or more reflections. At the apex, the

sound is then reflected one or more times, again, outwardly through the forward opening of the cabinet. The sound produced by the rear side of the loudspeaker is processed in a similar manner within its own rearwardly aimed horn means. However, since the speaker is not located equidistant from the apex and the mouth of the horn means, the distance travelled by the sound produced by one side of the speaker before escaping outwardly is not the same as the distance of the sound produced by the other side of the same speaker. As is the case when a speaker is located further away from the apex of the horn facing the opposite direction.

It should be noted that since the sound generated by each surface of a loudspeaker is divided into these three simply defined portions at the same time, the outward escape of each of these portions of sound is not accomplished at the same time, since there is only one horn opening for each surface side of a loudspeaker and each of the three portions of sound is consecutively located further away inwardly from the same opening.

BRIEF DESCRIPTION OF THE DRAWINGS Other features and advantages of the invention will be apparent from the following description taken in connection with the accompanying drawings wherein:

FIG. 1 is a front perspective view of a sound-reproducing structure embodying the invention, with a portion of the front grille removed to facilitate illustration of the structure;

FIG. 2 is an enlarged horizontal section taken substantially along line 2-2 of FIG. 1;

FIG. 3 is a rear view of the baffle means thereof;

H6. 4 is a front perspective view of a modified form of sound-reproducing structure embodying the invention; and

FIG. 5 is an enlarged horizontal section thereof.

DESCRlPTlON OF THE PREFERRED EMBODIMENTS In the exemplary embodiment of the invention as disclosed in FIGS. 1-3 of the drawing, a sound-reproducing structure generally designated 10 is shown to comprise a housing, or cabinet 11 comprising a wall means including a top wall 12, a bottom wall 13, a left sidewall 14, and a right sidewall 15, cooperatively defining a parallelepiped chamber 16. Chamber 16 opens forwardly through a front opening 17 of the housing l1 and rearwardly through a rear opening 13 thereof.

A bafile means generally designated w extends across the chamber to. in the illustrated embodiment, the baffle means comprises four

planar walls

20, 21, 22, and 23, cooperatively defining a pyramidal baffle, as best seen in FIG. 3. Each wall means is provided with a suitable opening 24 and is adapted to carry a loudspeaker generally designated 25 in coaxial relationship to its opening whereby sound generated by the loudspeaker may pass through the opening 24 and forwardly outwardly from the housing 11 through the front opening 17. Thus, a first portion of the sound produced by the loudspeaker 25 may be radiated directly outwardly through opening I7, as illustrated by dashed line 26 in FIG. 2. A second portion of the sound may be reflected from the opposing baffle, such as baffle 21, as shown by the dot-dash line 27 therein. A third, opposite phase portion of the sound may be radiated directly outwardly through rear opening 18 as shown by dotted line 28 therein.

' Thus, the invention comprehends that the baffle means 19 have at least one portion extending angularly to the lateral extent of the front opening 17 with a loudspeaker 25 mounted on the bafile wall to face angularly toward the front opening 17 thereby to disperse the sound in a new and improved manner from the housing or cabinet. As shown, the loudspeakers are preferably spaced forwardly of the apex 29 of the baffle 19 effectively defining the vertex of a pyramidal horn. Thus, the present invention provides improved low frequency response by virtue of spacing of the loudspeaker rearwardly of the front opening of the effective horn while yet providing high frequency response by virtue of spacing the loudspeaker forwardly of the vertex of the effective horn.

If high frequency loudspeakers, commonly referred to as tweeters, are desired, these may be located as desired on the bafl'le walls. A single tweeter, such as tweeter 32, may be provided on a single one of the baffle walls, or a plurality of such tweeters may be provided mounted on different baflle wall portions, as desired. As shown in FIG. 2, the tweeter 32 is preferably disposed forwardly of the low frequency loudspeaker for maximum efiiciency of radiation of the high frequency sound forwardly through opening 17.

If it is desired to use an acoustic suspension type of loudspeaker mounting arrangement such as discussed above, the rear opening 18 may be closed by a suitable rear wall 30 shown in dotted lines in FIG. 2.

In illustrating the invention, the front opening 17 is shown as extending horizontally. As will be obvious to those skilled in the art, the housing may be arranged with the opening uppermost. As is conventional with such upwardly opening cabinets, a sound reflector may be provided coaxially outwardly of the opening to deflect the sound horizontally to the listeners. When the rearwardly open arrangement of FIG. 2 is so mounted, it is desirable that the housing should be provided with a subjacent clearance of at least one-fourth the depth of the housing.

The height of the triangular walls 20-23, i.e., their dimension forwardly form the apex 29 as measured along the respective wall portions, may be varied as desired. In the illustrated embodiment, the altitude of each triangular portion is somewhat greater than the base defined by the forward edge thereof to provide a highly desirable bass response of the sound-reproducing structure as shown in FIGS. 1 and 2.

As shown in FIGS. I and 2, a conventional grille 311 may be provided across the front opening 17, as desired.

Referring now to FIGS. 45 and 5, a modified form of soundreproducing structure 10, generally designated 110, is shown to comprise a housing 111 defining a chamber 116. A baffle means 119 is provided within the chamber 116 comprising a single planar wall extending diagonally across the entire chamber from front opening 117 to rear opening I18. A single loudspeaker 125 may be provided on the wall M9. As discussed above relative to structure It), the rear opening 118 may be closed, as desired, by a suitable wall 130 where the loudspeaker 125 comprises an acoustic-suspension-type loudspeaker. Thus, in the embodiments of FIGS. 4 and 5, the second portion of the sound shown by dot-dash line 127 is reflected from the confronting housing wall 114 rather than from a baflle wall. However, in all other respects, the soundreproducing structure is similar to sound-reproducing structure 10 and functions'in a similar manner.

As will be obvious to those skilled in the art, configurations of housing 11 other than the parallelepiped configuration may be utilized. Thus, in lieu of the, square cross section of chamber 16 of housing 11, other cross-sectional configurations, such as triangular, circular, oval, polygonal of more than four sides, etc., may be utilized within the scope of the invention.

The foregoing disclosure of specific embodiments is illustrative of the broad inventive concepts comprehended by the invention.

I claim:

I. Sound-reproducing structure comprising: housing wall means defining a chamber having a front opening and a rear opening; baffle wall means extending fully across said chamber and having at least one portion extending angularly to the lateral extent of said from opening; and loudspeaker means facing solely toward the front opening of the chamber comprising a loudspeaker sealingly mounted in said baffle wall means intermediate said front and rear chamber openings to face angularly toward the front of said chamber to project sound from the front thereof outwardly through said front opening with a first portion of the sound being delivered directly forwardly outwardly through the front opening and a second portion of thesound being reflected from a portion of at least one of said wall means spaced from said loudspeaker, and to project oppositely phased sound from the rear thereof substantially only outwardly through said rear opening said baffle wall means comprising a plurality of individual wall means each having at least one such loudspeaker mounted therein, said individual wall means being arranged to define a pyramid having its apex directed away from said front opening, the space forwardly of said baffle wall means in said housing being concave and the space rearwardly of said baffle wall means in said chamber being convex.

2. The sound-reproducing structure of claim I wherein said pyramid comprises a four-sided pyramid.

3. The sound-reproducing structure of claim 1 wherein said pyramid comprises a four-sided pyramid having isosceles triangular sides.

4. Sound-reproducing structure comprising: a housing defining a rectangular parallelepiped chamber having an open front and an open rear; a pyramidal baffle means in said chamber having its base substantially coincident with the front of said wall means to open through said open front of the chamber, the apex of said pyramidal baffle means being adjacent said open rear of the chamber; and a loudspeaker sealingly mounted in each of sidewalls of said pyramidal baffie, said loudspeakers being symmetrically arranged about the axis of said open front of the chamber.

5. The sound-reproducing structure of claim 4 wherein said speakers are mounted on the altitude lines of said sidewalls extending from said base to said apex.

6. The sound-reproducing structure of claim 4 wherein said pyramid has a polygonal base having an even number of sides whereby said loudspeakers are disposed in opposed pairs, one each on the opposite sides of the pyramids.

7. The sound-reproducing structure of claim 4 wherein said baffle means extends fully to the open rear of said chamber.

8. The sound-reproducing structure of the claim 4 wherein said pyramidal baffle means opens axially perpendicularly to. the open front of the chamber.

Claims

1. Sound-reproducing structure comprising: housing wall means defining a chamber having a front opening and a rear opening; baffle wall means extending fully across said chamber and having at least one portion extending angularly to the lateral extent of said front opening; and loudspeaker means facing solely toward the front opening of the chamber comprising a loudspeaker sealingly mounted in said baffle wall means intermediate said front and rear chamber openings to face angularly toward the front of said chamber to project sound from the front thereof outwardly through said front opening with a first portion of the sound being delivered directly forwardly outwardly through the front opening and a second portion of the sound being reflected from a portion of at least one of said wall means spaced from said loudspeaker, and to project oppositely phased sound from the rear thereof substantially only outwardly through said rear opening, said baffle wall means comprising a plurality of individual wall means each having at least one such loudspeaker mounted therein, said individual wall means being arranged to define a pyramid having its apex directed away from said front opening, the space forwardly of said baffle wall means in said housing being concave and the space rearwardly of said baffle wall means in said chamber being convex.

2. The sound-reproducing structure of claim 1 wherein said pyramiD comprises a four-sided pyramid.

4. Sound-reproducing structure comprising: a housing defining a rectangular parallelepiped chamber having an open front and an open rear; a pyramidal baffle means in said chamber having its base substantially coincident with the front of said wall means to open through said open front of the chamber, the apex of said pyramidal baffle means being adjacent said open rear of the chamber; and a loudspeaker sealingly mounted in each of sidewalls of said pyramidal baffle, said loudspeakers being symmetrically arranged about the axis of said open front of the chamber.

6. The sound-reproducing structure of claim 4 wherein said pyramid has a polygonal base having an even number of sides whereby said loudspeakers are disposed in opposed pairs, one each on the opposite sides of the pyramid.

8. The sound-reproducing structure of the claim 4 wherein said pyramidal baffle means opens axially perpendicularly to the open front of the chamber.