US3032137A - Folded speaker enclosure - Google Patents

Description

y 1962 w. A. RICE 3,032,137

FOLDED SPEAKER ENCLCSURE Filed Sept. 5, 1957 2 Sheets-Sheet 1 ELE E CWWMR k INVENTOR ATTORNEYS 2 Sheets-Sheet 2 Filed Sept, 3 1957 INVENTOR %/V ,4 ,6

TTORNEY-5 Filed Sept. 3, 1957, S81. No. $1,594

4 Claims. (Cl. Isl-31) The present invention relates to a structurally improved folded corner horn or speaker enclosure. More specifically, the enclosure herein described is compacted into aminimum amount of room space for apartment installations where low cost and maximum fidelity of sound reproduction is required consistent with minimum over- .all space availability.

My invention constitutes a contribution over my previously patented Corner Horn, United States Letters Patent 2,754,926 which issued on July 17, 1956. While I there demonstrated that maximum low frequency sound reproduction efliciencies were best obtained with an unfolded type born, I have subsequently discovered a structure which, While of the folded type nevertheless is a considerable improvement over previously known folded type structures. While the unfolded horn disclosed in United States Letters Patent 2,754,926 achieves efliciencies of about forty percent, the horn of the present invention approximates a thirty percent efliciency in the low frequency ranges but employs a much simpler construction and can be scaled down in height to about one-half of the optimum size of the prior device. This results in the providing of a folded horn having bass range sound reproducing characteristics at least as good as previously known structures of the folded type, and, according to some comparative testing, better results. The cheapncss of producing the herein-described structure makes high fidelity speaker enclosures more available to a wider range of people and adapts the enclosure product to installations such as apartments where space is at a considerable premium.

Accordingly, it is among the objects of the present invention to provide a small folded type speaker enclosure which is extremely simple in its construction.

Another object of the present invention is to provide a folded type enclosure having a speaker to air coupling in the range of approximately thirty percent efficiency at low audio frequencies.

Another object is to provide a corner horn which simultaneously uses vertical sound column flare extension made available by adjacent intersecting wall planes, and utilizes a third projecting plane along the floor.

Another object is to provide a horn structure in which the flare progression is selectively modified by simple dimensional alteration of the baffle plates.

Still another object is to provide a speaker enclosure amenable, by reason of its simplified design, to plastic molding and the like.

Other objectives, including the provision of a useful piece of home furnishing of relatively small size will be come increasingly apparent to those skilled in the art as the description proceeds.

in the drawings:

FIGURE 1 is a frontal perspective view of the speaker enclosure illustrating its assembled simplicity.

FIGURE 2 is a cross section elevation view taken on line IIII of the structure shown in FIGURE 4 with the top plate added and illustrates the internal chambering and flare progression.

FIGURE 3 is a perspective view of the base element of the assembled structure.

FIGURE 4 is a top plan view of the device as shown in FIGURE 1 with the cover removed.

FIGURE 5 is a schematic graphic presentation indicatatent p 3,032,137 Patented May 1, 1962 General Description In general, the present invention comprises a floor model speaker enclosure having a base member which is tripodally mounted. The base is of such configuration (triangular) as to fit the entire structure into the corner of a room. The foremost corners of the base are truncated to accommodate vertically extending closure mem bers.

Two chambers are provided. The first of the chambers is that in which the speaker, preferably of the back loaded coaxial type, is mounted. The selection of the coaxial speaker is desirable since such speakers project high frequency sound columns frontally and are highly eflicient. The low frequency impulses are emitted from the rear of the speaker, and the efficiency of the bass range sound reproduction is dependent upon the coupling as between driver and the air column and the flare rate established by the form of the enclosure. The first chamber is thus arranged to receive the sound impulse under the best possible coupling conditions and to move the sound column through a throat area located near the top of the chamber where the sound column commences its progressive flare on entry to the second chamber. The second chamber is separated from the first chamber by a pair of barriers spaced apart from closure with a: top to define an opening or throat as between the first and second chambers. The second chamber achieves its progressively opening flare by reason of a pair of downwardly and rearwardly inclined rear bafiles. The second chamber is enclosed at the ends by suitable closures. The second chamber delivers the low frequency impulses downwardly through openings in the base member where it is further flared by the proximate extensions of floor and adjacent Walls. Variance is made possible in the flare rate by the adjustment of the inclined baflles. At the top, closure of the chambers is accomplished by a suitable cover. Diffusion or continuous flaring of the column is accomplished when the sound column is passed along floor and adjacent room walls.

Specific Description Referring more particularly to the drawings, and with reference to FIGURE 1, the entire enclosure 11 rests upon a generally triangular base 12, the base 12 being spaced above floor level and supported by the tripo'dal legs 13. As best shown in FIGURE 3, the triangular base 12 is arranged at right angles at the rear so as to fit the enclosure 11 into the corner of a room. The front of the base 12 is formed from the hypotenuse of the triangle established by the base 12 and the front corners is are truncated at right angles to'the back struts l5 and 16. The object to truncating the front corners 14 will become more apparent as the description proceeds. A base plate 17, of triangular configuration extends rearwardly in cantilever fashion from the front strut 18. This arrangement leaves the contiguous opening 19 as further defined by the members 15, 16 and 17 and the truncations 14.

Referring to FIGURES 1 and 6, the base 12 is provided with the front plate 20 which is rectangular in formand coextensive with the strut member 18. The plate 20 is provided with a circular opening 21 which is symmetrically positioned with respect to the sides of the plate 10, but

sesame downwardly on the entire plate 20. The opening 21 provides an opening for the mounting of a selected driver or speaker 22. The speaker 22 is preferably of the coaxial back loaded type and is preferably peripherally attached to the plate 20 at the edge of the opening 21.

From the base plate 17, establishing a triangular base pattern, vertical barriers 23 and 24 arise to provide a prismoidal first chamber 25 (FIGURES 2 and 4) of triangular cross section when considered in association with the front panel 20 and base plate 17. Spaces 26 and 27 are provided at the upper edge of the barriers 23 and 24 respectively to define a throat opening 28. When assembled the barrier members 23 and 24 are joined as best indicated in phantom lines in FIGURE 1.

Spacedly behind each of the barrier members 23 and 24 are planar baifies 29 and 30. These bafiies 2.9 and 30 rise from the base struts 15 and 16 respectively and incline forwardly therefrom, their edges 31 and 32 meeting in a common seam as shown best in FIGURES 1 and 4. Considered from the top of the structure, the flare is downward and rearward. Rectangular end plates 33 and 34 rise vertically from the truncated corners 14 of the base 12 and close against the front panel 2t) and the external edges of the baflie members 29 and 3%. A top closure 35 of generally equal configuration with the plan trace of the base 312- is fitted to close on the upper edge of the front panel 29. This arrangement thus describes a second chamber '36 (FlGURE 2) flaring downwardly and outwardly and defined by the barriers 23 and 24, the bafiles 29 and 36, the end plates 33 and 34 and the top closures 35. At the bottom of the chamber 36 is opening I? through the base '12.

Tracing the sound column of the bass frequencies, the back loaded speaker 22 acts on the chamber 25 moving the column through the throat 28 and into chamber 36. The moving column emits its sound frequencies through the opening 1% to the room where it is confined by the walls and fioor. In FIGURE is a graphic presentation of the column progression from the speaker to the room in stage through chambers 25 and 36.

As will be understood, the front panel 20 may be decoratively covered with fabric or grill and suitable acoustical putty is used to dampen resonance vibrations in the joinder of the structural members. Since the enclosure 11 is basically constructed of sheet material throughout, the device is amenable to knock-down shipping for simple assembly at the point of use. By the same token, the structure is readily amenable to plastic molding in a unitary manner and through simple dimensional changes in the bafiles 29 and 30, the flare progres sion may be altered to suit any specific taste in audio bass frequency reproduction.

Operation In operation the device is highly efficient at a height of approximately 30 inches from the floor level making possible excellent audio reproduction of low frequency sound. The low frequency efficiency level in audible ranges approximates thirty percent as contrasted with normal speaker efficiencies of to v12 percent. The present speaker enclosure is not as efficient as my Corner Horn described in United States Letters Patent 2,754,926 but the presenthorn :is considerably more compact and considerably simpler in construction contributing materially to a reduction in cost with small sacrifice in bass frequency fidelity. As will be appreciated, the reorienting of the progression or flare in the second chamber may be easily adjusted which is also true of the throat dimensions so as to provide simple adjustments to suit particular auditory tastes.

Having thus described my improved speaker enclosure it will be appreciated that various modifications within the skill of the art may be made, and such improvements are intended to be included in the hereinafter appended claims.

I claim:

1. in a speaker enclosure, the combination including: a substantially triangular base member having the forward corners thereof truncated; a front panel defining a speaker mounting opening; a pair of vertically rising barriers shorter than said front panel spacedly defining .a throat rea at the top; a triangular base plate closing against the said vertical barriers .at the bottom; a top closure defining with said barriers, said base and said front panel a first chamber of prismatic form having a triangular cross section open through the throat area of said barriers; and a pair of downwardly and outwardly inclined planar bafiles spacedly behind said barriers; vertically rising end closure members extending from the truncated corners of said base member and closing on said baffies at the sides to define with said top closure and said barriers a second chamber of double prismoidal form open at the bottom through said base plate member to provide emission of a sound column from said second chamber to the room, the emission being confined by adjacent walls and floor.

2. In a speaker enclosure, a legged right triangular base member having each of the apices connecting the hypotenuse truncated; a rectangular front panel rising vertically from the remaining hypotenuse portion of said base member and defining therethrough an opening for mounting of a speaker on a horizontal axis; a triangular base plate having its hypotenuse coextensive with the remaining portion of the truncated hypotenuse side of said base member and extending horizontally; a pair of vertical rising barriers extending upward from said base plate and defining with said front panel a substantially prismatic first chamber; a horizontal corner truncated triangular top closure in spaced register with said base member and attached to the upper edge of said front panel but gapped from connection with said vertical barriers to provide a throat opening between said barriers and said top closure; a pair of downwardly and outwardly inclined planar baffles spacedly behind said barriers and connecting at their upper edges to said top closure; and a pair of rectangular end closures rising vertically from the truncations of said base member and attached at their upper edges to the truncations of said top closure and closing on said inclined battles and defining thereby a second chamber of double prismoidal configuration, open at the bottom to form a mouth for sound emission and having an upper transverse throat entry from said first chamber.

3. In a corner horn speaker for mounting coaxial back loaded speakers, the combination including: a first prismatic chamber of triangular cross section defined by three vertically rising planar elements, two of said planar elements being shorter than the third and said third planar element having speaker mounting means and said first chamber being closed at the base; a second chamber of double prismoidal form slanted spacedly behind said first chamber and of a height equal to said third planar element so that said first and second chambers merge, said second chamber increasing in cross section area downwardly, closed at the edges and at the top; and a base plate member carrying said chambers spacedly above floor level and closing said first chamber at the bottom and defining an opening therethrough for said second chamber.

4. In a speaker enclosure the combination including; three vertical planar walls defining a first prismatic speaker chamber of triangular cross section, one of said Walls having a speaker opening therethrough and the walls opposite thereto being shorter than said speaker and having a merged throat opening thcrethrough proximate the upper portion of said Walls; a pair of slanted planar Walls spaced apart from said shorter walls and with said shorter walls defining a double prismoidal form second chamber connected to said first chamber by said throat opening, said second chamber having progressively larger cross sectional area in the downward direction; a

transverse cover member supported by said speaker wall 2,754,926 and said slant walls and extending rearwardly therefrom; 2,765,864 a base plate closing said first chamber at the bottom 2,792,069 thereof and supporting said slant walls while leaving said second chamber open at the bottom, said base plate 5 spacedly elevating said chambers above a floor level; and 477 749 rectangular planar side closure plates closing the ends of 765 183 said second chamber.

References Cited in the file of this patent UNITED STATES PATENTS 2,373,692 Klipsch Apr. 17, 1945 6 Rice July 17, 1956 Glenn Oct. 9, 1956 Gately May 14, 1957 FOREIGN PATENTS Great Britain May 18, 1936 Great Britain Jan. 2, 1957 OTHER REFERENCES 10 Brociner Corner Horn, High Fidelity, May-June edition,

vol. 3, N. 2, 1953, page 90.

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