|Publication number||US2731101 A|
|Publication date||Jan 17, 1956|
|Filing date||Jun 6, 1952|
|Priority date||Jun 6, 1952|
|Publication number||US 2731101 A, US 2731101A, US-A-2731101, US2731101 A, US2731101A|
|Inventors||Klipsch Paul W|
|Original Assignee||Klipsch Paul W|
|Export Citation||BiBTeX, EndNote, RefMan|
|Patent Citations (3), Referenced by (15), Classifications (6)|
|External Links: USPTO, USPTO Assignment, Espacenet|
Jan. 17, 1956 P. w. KLIPSCH 2,731,101
LOUD SPEAKER Filed June 6, 1952 By Paul W K/Losc/v Age/ifs United States This invention relates to a loud speaker system, and more particularly such a system which combines direct radiation of high frequencies and corner horn back-loading of the driver unit for low frequencies. The invention is especially useful in its application to loud speakers installed in the home for faithfully reproducing radio telephonic reception and phonograph records, to which use, however, the invention is not limited.
Combined direct radiation of sonic high frequencies and indirect corner horn radiation of sonic low frequencies is not broadly new. In my Patent No. 2,310,243, granted February 9, 1943, for Horn for Loudspeaker one such system is disclosed. Such apparatus gives faithful reproduction of an extended bass range down through low C of the organ, and at the same time accurate reproduction up to the highest audible sounds. Furthermore, the response of apparatus such as that disclosed in my said patent is smooth over its entire sonic range, giving complete coverage of the listening area wtihout either hot or dead spots. Such known apparatus depends for its operation upon long acoustic passages and internal baflies.
I have now found it possible to provide a combined direct radiation and corner horn loud speaker system which gives an acoustic response approaching that of the apparatus disclosed in my aforesaid patent, and which at the same time is simple, inexpensive and of low bulk, and which provides low distortion and extended bass frequency range.
According to the present invention the entire horn is formed outside of the housing, and the housing itself forms a very simple acoustic low pass filter which limits the bass range efficiency to an order of magnitude comparable with the middle range efficiency of the direct radiator action. The housing forms a simple cavity which is unobstructed except for immersion of the driver unit therein. An acoustic inertance, in the form of an orifice or slit suitably formed in the housing, coacts with the cavity to provide the lowpass filter. The front panel of the housing has a opening therein, and the driver unit is mounted in the cavity upon the front panel rearwardly of this front opening, through which the treble sound radiation leaves the housing. The side panels of the housing extend convergingly rearwardly of the front panel to form, in conjunction with external proximate surfaces, the horn portions of the speaker, and to form with the front panel an acoustic capacitance in the form of an unobstructed cavity. At the rear of the cavity an acoustic inertance is provided in the form of a constricted opening or orifice, through which the bass frequency sound enters the horn. Thus the cavity and the orifice form the low-pass filter for the bass frequency sound between the driver unit and the born.
The invention is shown by way of illustration in the accompanying drawings, in which Fig. 1 is a horizontal section taken through a speaker constructed and arranged according to the invention, together with the wall angle providing the proximate suratent faces forming the external horn, the section being taken on the line I-I of Fig. 2.
P Fig. 2 is a front elevation of the speaker shown in Fig. 3 is a vertical section taken through the speaker shown in Figs. 1 and 2, the section being taken on the line III-III of Fig. 2, and
Fig. 4 is a horizontal section, similiar to that shown in Fig. 1 illustrating a different type of speaker also con structed and arranged according to the invention.
In the embodiment of the invention which is illustrated in Figs. 1, 2 and 3 of the drawings, there is shown a generally prismatic-shaped speaker or housing 10 symmetrically disposed with respect to proximate surfaces 11, 11 which are provided as by the walls of a room meeting in a corner at The speaker 10 comprises a housing, an important part of which is a front panel 12, having an opening 13 therein between its side edges. Side panels 14, 14 are joined at their forward edges to the front panel at its side edges, and extend convergingly rearwardly therefrom at equal angles thereto and at an acute angle to one another. Coplanar panels 15, 15 extend inwardly from the rear edges of the respective side panels to a slot or orifice 16 in the rearmost part of the housing. As here shown the slot or orifice 16 is a slot extending from top to bottom of the housing.
A bottom panel 17 closes the lower end of the cavity 18 formed by the front panel 12, the side panels 14, 14 and the rear coplanar panels 15, 15; and a top panel 19 closes the top of the cavity so formed. Thus, the cavity 18 constitutes an acoustical capacitance or resonance cavity, completely closed except for the opening 13 in the front panel and the slot or orifice 16 formed at the rear center of the cavity between the rear coplanar panels 15, 15.
A cover 20 is fixed to the upper surface of the top panel 19, and its extent is such as to meet the walls or proximate surfaces 11, 11 when the speaker is suitably placed. Thus the cover 20 cooperates with the walls to form horn sections 21 and 22 between the side panels 14, 14 and the proximate surfaces 11, 11. The lower limit of the horn sections is, of course, defined by the floor.
The driving unit 23 of the speaker is mounted upon the front panel 12, rearwardly of the opening 13, therein, within the cavity 18. Thus the driving unit is immersed in the cavity, which is otherwise unobstructed, and closes the opening 13, through which is treble sound of the unit leaves the speaker. The bass frequencies of the driving unit enter the cavity 18, pass through the low pass filter formed by the acoustic capacitance of the cavity and the acoustic inertance of the slot 16 and thence enter the throat of the horn, passing outwardly therefrom through the two horn sections 21, 22. It has been found that best results are obtained when the area of the slot 16 is appreciably smaller than that of the horn throat.
The speaker has been built experimentally in a size thirty-six inches high. The response of such speaker has been found to be very good down to 35 cycles, and produces usable fundamental output down to 30 cycles. In the speaker referred to, the cutoff is 30 cycles, the wave length is 450 inches or substantially twelve times the height of the speaker, and the acoustic cut-oif is about cycles. The side panel convergence has been designed to provide a horn cut-01f of the order of a wave length twelve times the height of the housing, and this design is such that the cavity-slot low-pass acoustic filter cut-off frequency is of the order of four times the frequency of the horn cut-off.
The driving unit 23 may be of any known or convenient form, and good results have been obtained with such units known as Alice 6043, Jensen G-6l0, University 6201, and other coaxial and simple driver systems. In such tests it has been observed that at least one octave more of clean fundamental bass output has been obtained than that which can be realized with ordinary baffle cavities.
As illustrated in Figs. 1, 2 and 3, the front panel 12 is a composite panel comprising a central element in which the opening 13 is formed and upon which the driving unit is mounted, and coplanar elements 25 and 26 on either side of the central element to which the side panels 14, 14 are fixed. The central element 24 of the front panel 12 is made unitary with the coplanar elements 25 and 26 by means of longitudinal strips 27 and. 28, the central element, the coplanar elements and the longitudinal strips extending from top to bottom of the front panel. The arrangement described is found to give desirable resonance to the speaker 10. However, whether or not such composite construction is employed, it has been found that the customary sound-deadening material is not needed in speakers constructed and arranged according to the invention.
It is to be noted that the opening 13 is positioned as high as possible in the front panel to effect frontal direct radiation in a high region of the speaker which is more nearly on the level of the ears of the listener than would be the case were the driver unit positioned at a lower level in the speaker.
The loud speaker system herein described combines direct radiator performance for high frequencies and corner horn back loading of the driving unit for base frequencies. The acoustic low-pass filter is interposed between the back of the driving unit and the throat of the horn, whereby the bass response is flattened. The entire horn is outside of the housing, and the entire housing space is devoted to cavity, with the exception of the space required for immersion of the driver unit therein. The low-pass filter, with a gradual slope, feeds back to the horn throat which is roughly proportional to the bass wave length. Accordingly, the sound output remains reasonably constant.
From the horn throat, immediately back of the slot or orifice 16, the sound wave expands in the horn sections 21 and 22; and the horn design is deliberately made so that the efficiency will drop with frequency, in order that the combined operation of the horn and the acoustic filter may offer a reasonably flat response in the bass frequency range and in offering bass output of approximately the same intensity as that radiated through the opening 13 in the front panel 12.
For the reasons just stated the horn is made short and a of smaller mouth size than would ordinarily be considered good design for a fully horn loaded loud speaker system. As a result of the decreased horn size, combined with the described simple acoustic filter, a horn efficiency which is approximately proportional to frequency over a two-octave range is realized.
In the embodiment which is illustrated in Fig. 4 a similar speaker 16:: is shown. However, in this form of speaker the front panel 12a is not of composite construction and the side panels 140, 14a extend directly rearwardly of the front panel to form between them a slot or orifice 16a; and no coplanar panels 15, 15 are employed in forming the speaker. The resulting cavity 18a is slightly smaller than the cavity 18 formed by the speaker illustrated in Figs. 1, 2 and 3 but the construction and use of the speaker 10a is otherwise the same.
A loud speaker system constructed and arranged according to the invention gives a wider tonal range than can be obtained from simple battles and resonated enclosures of comparable size. It provides adequate loading of the driving unit diaphragm near the diaphragm suspension, effecting reduction of diaphragm excursion with resultant reduction in diaphragm distortion. Furthermore, reduced intermodulation distortion results from reduced diaphragm excursion, and the present invention thus reduces such inter- 4 modulation distortion. It is particularly to be noted that reduction of diaphragm excursion is effected by imposing radiation resistance, so that bass output is increased rather than reduced. Such results are realized in simple and inexpensive manner in a speaker of small volume.
The forms of the invention here described and illustrated are presented merely as examples of how the invention may be applied. Other forms and embodiments coming within the proper scope of the appended claims will, of course, suggest themselves to those skilled in the art.
1. In a corner horn loud speaker, a prismatic-shaped housing for symmetric location in a corner formed by the walls of a room to provide a length of horn between the housing and the room walls, said housing forming a closed cavity and comprising a front panel having an opening therein to exhaust treble sounds from a driver unit mounted upon said front panel at the opening therein, said housing also comprising rearwardly converging side panels forming a slot-like port to exhaust bass frequencies into the throat of the horn formed between said housing and the room Walls.
2. A speaker according to claim 1, in which the size of the cavity and slot-like port are coordinated to form a lowpass filter.
3. In a speaker according to claim 1, side panel convergence providing a horn cut-off of the order of a wave length twelve times the height of the housing, and a cavity-slot low-pass acoustic filter cut-off of a frequency of the order of four times the frequency of the horn cutofif.
4. A corner horn loud speaker comprising a driver unit, in combination with a cavity-slot acoustic low-pass filter fed by one side of said driver unit, and an acoustic horn external to said filter, a part of which is formed by said filter, said filter being constructed and arranged to feed the throat of said acoustic horn.
5. In a corner horn speaker system for use with a direct radiator driver unit for treble frequencies and a corner horn bass loading of one side of the driver unit for bass frequencies; a prism-shaped housing constructed and arranged to form a length of horn between said housing and the walls forming a corner in a room, said housing providing an acoustic capacitance in the form of a cavity therein, said housing having therein an acoustic inertance in the form of an orifice positioned to feed sound waves into the throat of the horn formed between said housing and the room walls, and the acoustic capacitance and acoustic inertance in said housing providing a low-pass filter between the driver unit and the horn throat.
6. A corner horn loud speaker according to claim 1 wherein the slot is appreciably smaller in area than the throat of the horn.
7. A corner horn loud speaker according to claim 5 wherein area of the orifice is appreciably smaller than that of the throat of the born.
8. A loud speaker of the corner horn back-loading type comprising a front panel having an opening therein between its side edges, side panels joined at their forward edges to the side edges of said front panel extending convergingly rearwardly at equal angles thereto and at an acute angle to one another to define with said front panel an unobstructed cavity and to form an inertance opening of small size at their rearmost points of convergence, and a driving unit mounted upon said front panel rearwardly of the opening therein within the cavity defined by said front panel and said side panels.
9. A loud speaker of the corner horn back-loading type comprising a front panel having an opening therein between its side edges, side panels joined at their forward edges to the side edges of said front panel extending con ergingly rearwardly at equal angles thereto and at an acute angle to one another to form a slot at their rear edges and to define with said front panel an unobstructed cavity. and a driving unit mounted upon said front panel rearwardly of the opening therein within the cavity dc fined by said front panel and said side panels.
10. A loud speaker of the corner horn back-loading type comprising a front panel having an opening therein between: its side edges, side panels joined at their forward edges to the side edges of said front panel extending convergingly rearwardly at equal angles thereto and at an acute angle to one another, coplanar panels joined to the rear edges of said side panels and extending toward one another to form a slot at their unconnected edges, said side panels and said coplanar panels defining with said front panel an unbaffled cavity, and a driving unit mounted upon said front panel rearwardly of the opening therein within the cavity defined by said front panel and said side panels.
11. A loud speaker cabinet wherein side panels thereof coact to provide horn sections with proximate surfaces fixed at substantially 90 to one another to form a corner in which the cabinet is symmetrically disposed, said cabinet comprising: a front panel; side panels extending reawardly from the side edges of said front panel at equal angles thereto and at an acute angle to one another; a top panel fixed to the upper edges of said front panel and said side panels; and a bottom panel fixed to the lower edges of said front panel and said side panels; said front panel, said side panels, said top panel and said bottom panel defining an unobstructed cavity; and said side panels forming at their rearmost points of convergence an inertance opening of small size to admit low frequencies to the horn beyond said cabinet.
12. A loud speaker cabinet wherein side panels thereof coact to provide horn sections with proximate surfaces fixed at substantially 90 to one another to form a corner in which the cabinet is symmetrically disposed, said cabinet comprising: a front panel; side panels extending rearwardly from the side edges of said front panel at equal angles thereto and at an acute angle to one another;
a top panel fixed to the upper edges of said front panel and said side panels; and a bottom panel fixed to the lower edges of said front panel and said side panels; said front panel, said side panels, said top panel and said bottom panel defining an unobstructed cavity; and said side panels forming at their rearmost points of convergence a slot extending the entire height of said cabinet to admit low frequencies to the horn beyond said cabinet.
13. A corner horn loud speaker comprising a prismatic shaped housing for symmetric location in a corner formed by the walls of a room to provide the entire horn of the speaker between said housing and such walls, said housing comprising a hollow shell bounded by a substantially plane front panel and side panels converging rearwardly therefrom, the front panel of said housing having an opening therein to exhaust treble sounds from a driver unit mounted upon the front panel at the opening therein and immersed in the hollow shell formed by said housing, and the side panels of said housing converging rearwardly therefrom, said housing having a vertical slot formed centrally of its rear extremity to exhaust low frequency tones into the corner formed by the walls of the room.
References Cited in the file of this patent UNITED STATES PATENTS 2,310,243 Klipsch Feb. 9, 1943 2,337,213 Topping Dec. 21, 1943 2,373,692 Klipsch Apr. 17, 1945 OTHER REFERENCES Publication (II) Elements Acoustic Engineering by Olson, 2nd edition, pages 208-209. (Copy in U. S. Patent Office TK5981.05.)
McProud: A New Corner Speaker Design," article in Audio Engineering, January 1949 (pages 14-17 and 39).
|Cited Patent||Filing date||Publication date||Applicant||Title|
|US2310243 *||Feb 5, 1940||Feb 9, 1943||Ray L Smith||Horn for loud-speaker|
|US2337213 *||Nov 3, 1941||Dec 21, 1943||Jr Joseph Topping||Pressure control loud-speaker enclosure|
|US2373692 *||Oct 3, 1942||Apr 17, 1945||Ray L Smith||Loud-speaker|
|Citing Patent||Filing date||Publication date||Applicant||Title|
|US2858899 *||Jul 3, 1956||Nov 4, 1958||Miguel Lopez-Henriquez||High fidelity speaker enclosure system|
|US2949163 *||May 6, 1957||Aug 16, 1960||Soundolier Inc||Loudspeaker baffle assembly|
|US2955669 *||Aug 16, 1957||Oct 11, 1960||Carl E Grebe||Triplanal speaker enclosure|
|US3138220 *||Sep 29, 1960||Jun 23, 1964||Glindmeyer Victor B||High fidelity speaker mounting|
|US3203502 *||Apr 28, 1964||Aug 31, 1965||Rife Marjorie M||Corner speaker enclosure|
|US3908503 *||Nov 6, 1973||Sep 30, 1975||Bolin Gustav Georg Arne||Device in stringed musical instruments|
|US3983333 *||Apr 7, 1975||Sep 28, 1976||Allison Acoustics Inc.||Loud speaker system|
|US4171734 *||Nov 10, 1977||Oct 23, 1979||Beta Sound, Incorporated||Exponential horn speaker|
|US4509192 *||Apr 7, 1983||Apr 2, 1985||Straughn Roy D||Speaker enclosure|
|US4790408 *||Jan 25, 1988||Dec 13, 1988||Adair John F||Coiled exponential bass/midrange horn loudspeakers|
|US4870691 *||Apr 13, 1987||Sep 26, 1989||Mindel Gerard S||Load and dispersion cell for sound|
|US8064627||Oct 21, 2008||Nov 22, 2011||David Maeshiba||Acoustic system|
|US8406444 *||Mar 26, 2013||Chao-Lang Wang||Audio radiation type reflective sound box structure|
|US20110235845 *||Sep 29, 2011||Chao-Lang Wang||Audio radiation type reflective sound box structure|
|US20120061174 *||Nov 21, 2011||Mar 15, 2012||David Maeshiba||Acoustic system|
|U.S. Classification||181/148, 381/160, 381/349|