US 3026955 A
Description (OCR text may contain errors)
H. L. WILBER SPHERICAL LOUDSPEAKER ENCLOSURE March 27, 1962 Filed Aug. 23, 1956 Ihre far May/4Z@ United States Patent @hace 1. 3,026,955; SPHERICAL LOUDSPEAKER ENCLOSURE Howard'L. Wilber, 1340 Knoxville St.,
vSian Diego 10, Calif. FiledfAug. 23, 1956Ser. No. 605,866 3 Claims. (Cl. 181-31.)
This invention relates to loudspeakers and associated loudspeaker enclosures, and'moreparticularly to the combination of loudspeakers and'associated loudspeaker enclosures, for an eiicient means of combining the two into` a working system, whereby the design and application of the enclosure primarilyy promotes the eiciency ofthe combination, achieving appealing Vand satisfying audio reproduction.
An object of the invention is to provide a nearly perfect combination ofi loudspeaker and loudspeaker enclosure working together in vcombination as a means of reproducing el'hciently, pleasantly, andsatisfyingly, sound waves propagated by loudspeakers in `antunit that is durable, long-lastingyinert to most elements, climatic conditions, is decorative, versatile, light in weight, colorful in various color combinations, easy to produce economically, adaptable to many applications as a source of entertainment,` communication,information, intelligence, and education..
This invention is an improvement over allother .combinations of loudspeakers and loudspeaker enclosures, and loudspeakers and loudspeaker enclosures separately, in thatbeing of different concept .and application, fit provides more` eicient, pleasant, and satisfying reproduction of the audio spectrum.
In a specic embodiment of the invention herein ShownVv anddescribed forthe purpose ofr illustration, there is provided in combination: a loudspeaker enclosure of the in linite-balile type, `spherical in shape, Working. in com'- bination with a loudspeaker or several loudspeakers mounted `and attached therein, a means of attaining the sperical enclosure comprising two fhemispherical halves, each comprising a main rigid shell with provisions for mounting and attaching loudspeakers for operation therein, a means of protecting said loudspeakers from damage comprising a protective grille for eachrespective loudspeaker mounted therein, a ,means` of attaching said grilles into the combination, a sound-absorbing lining and a. means tof; attachingsaid liningtosaidouter shell, a. means of attaching the two hemispherical halves together in combination for. a. working unit comprising a. joining member to receive .theedgesof .both hemispherical halves, and suitable meansofattachment comprising aplurality or.' fasteners around .the.diameter of the spherical combination,v a means of .connecting thev` above combination to associatedA electrical .equipment for operation comprising suitable electrical. wires, and ameans-of access to the respective.loudspeakers-for said wires, a means of" supporting .the combination for. operation comprising al lixture for the attachment of a; rope, cable, chain, etc., to saidl combination, for the purpose of hangingsaid combination like a chandelier for suspended operation in a room, auditorium,` theatre, etc., or for optional operation at .the discretion ofthe user, a, suitable, mount 23 for said combination to rest upon, allowing the combination to be rotated into its optimum operating orientation in the place of operation, and provisions for decorative coloring for appealing color schemes.
FIGURE l is an elevational view with parts broken away, FIGURE 2 is -a view taken along line 2-2 of FIG- URE 1, and FIGURE 3 is a sectional view showing how the hemispheres are connected.
In the accompanying illustrations, FIG. l illustrates basically the minimum concept for description of this invention, showing provisions for the above named comy 3,026,955 Patented Mar. 27, 1962 bination comprising the above-described spherical loudspeakerl enclosure with provisions for one loudspeaker installed therein, comprising ya spherical shell y1, comprising two hemispherical halves 2 and3, each comprising a -rigid hemispherical shell of molded plastic or other suitable formable material I4` and S, a sound-absorbing liningl 6 and 7, provisions'for'mounting loudspeakers therein comprising a, molded llat'surface on thelinner surface of the shell, a large hole 8 rounded outward from inside, av
plurality of small holes 9v radially symmetrical about the respective larger hole, and centered onl a radiusl larger than theradius of hole 8, a means of attaching the soundabsorbing lining` 6 and 7 to the respective hemispherical shells 4 and 5 comprising an adhesive 1i), a means of`V attaching the loudspeakers therein to be mounted comprising suitable screws or other suitable attachments 11 and suitable nuts orA other suitable facsimile 12, and for the purpose of illustration a loudspeaker 13, a protective grille `14 for said loudspeaker, and al means of attaching said grille comprising screws and .nuts 11 and 12 above or other suitable means, a means of attaching the twof rative trim to the shell 41, a means of access for the Wires fromassociated electrical equipment to be connected to theloudspeaker 13 comprising a hole 19 through half 2' or optionally through haif 3 in a location that is optimum for a particular installation of shell 1 depending upon the orientation desired by the user, and -a two conductor electrical wire 20 to connect loudspeaker 13 to associated electrical equipment for thepurpose of operation of the combination unit, a means of suspending saidl combination comprising a suitable fixture 21 and 22 and a means of mounting said combination comprising a suitable stand 23. As shown in FIG. l, a tri-legged, stand with interi connecting bands is preferred for styling and function.
FlG. 2 illustrates an elaboration of FIG. 1, and is obtained by cutting the combination shown as shell 1, in FIG; 1, in a plane described by line 2,-24 and viewing said combination at right `angles to said plane described bysaid line 2 2.
Sound, when propagated, radiates in spherical. Waves from a source in air (atmosphere). Consisting of areas ofcompression and `rarelication betweenthe various wave fronts, the air particles develop a complex acoustical pattern, travelling'spherically to and fro between the compressed and rarelied areas, depending. upon the nature of the propagated sound at the source. If a vibrating diaphragm is used` as a source, e.g., adiaphragm of a direct-` radiating type loudspeaker, driven by a program of electrical` currentthrough its motor assembly, the vibrations of said diaphragm will be coupledto the surrounding air, both, in front and behind, the diaphragm. Coupling of energy to the air takes placeand consequently, the energy coupled to the air in front of the diaphragm is out of phase or in exact opposite direction to that coupled to the air behind the diaphragm.
If sound waves, when propagated as described above, in back of the diaphragm are not isolated from the sound waves in front of the diaphragm, the two waves traveling in opposite spherical directions will cancel each other to a drastic extent when they interact as they travel past the edge of the diaphragm. The amount of cancellation depends upon frequency/ wavelength factor, and respective 3 travel/speed/frequency factor; in general, it is an extremely adverse situation. The desired goal is then, to obtain the ultimate eflciency throughout the audio spectrum, of radiation from a direct-radiating type loudspeaker,
If the loudspeaker is placed in an enclosure, so that the edge of the diaphragm is as near to the outer surface ofthe enclosure as possible, and the loudspeaker assembly frame attached to this enclosure securely, the back of said loudspeaker thus being totally enclosed within said enclosure, the front sound wave is isolated from the rear sound wave. The diaphragm is free to vibrate and couple the sound it generates to the adjacent air in front, and the rear sound wave is prevented from cancelling the front sound wave because it is confined to the inside of the enclosure.
The front wave is desired in its entirety, but the back wave is not wanted, unless it can be inverted and broughtl out in front, in phase with the front wave. This is only possible by complex baffle arrangements, ducts, etc., as is used in the wood-constructed types of enclosures, and only at certain frequencies, due to the frequency/wavelength, and frequency/speed factors. Some loudspeakers do use that method of phase inversion principle, but they have a characteristic of peaking at certain frequencies, because of the above-mentioned factors, and so therefore, detract from a true dispersion of smooth response by reinforcing certain frequencies, and neglecting others.
With the front wave only being used, a smooth response of the capabalities of a loudspeaker is attained, but what happens to the back wave? If the enclosure is a boxshaped affair, with straight sides, even though the interior of the box is lined with a sound-absorbing material to expend the sound energy, the box must be made relatively large, and even then, the parallel surfaces of the interior allow the sound to travel between them in what are known as standing waves. These standing waves interfere with the operation of the loudspeaker cone in much the same manner as the interaction of the front and back waves without the enclosure, so they must also be eliminated.
When the enclosure is a sphere, it is on its way to the ideal, the ultimate, in a loudspeaker enclosure. A spherical shell has no parallel surfaces on its interior. Instead, it is a continuously-enveloping surface, all points spherically equidistant from its center. A sound wave emitted into its interior radiates spherically from its source, and being reflected by the spherical wall of the interior cavity, focuses into a point of self-cancellation vectorially at the center of the spherical cavity. Complete cancellation takes place. This is the ideal, and also permits reduction of the size of the spherical enclosure to an optimum, far smaller than is possible with conventional box-shaped enclosures.
The back wave has now been eliminated, and now the front wave shall be considered. Outside, in front of the loudspeaker, the front wave is radiating outward in a spherical pattern from the diaphragm. In a box-shaped enclosure, when it reaches the edge of a side, the surface disappears to a sharp angle of usually 90 from the side of propagation. The sound wave loses support from this surface immediately upon reaching these edges and diffraction of the wave takes place, producing distortion right at the source of radiation. The purpose of good, efficient, clean, realistic sound is therefore defeated.
i However, with the spherical enclosure, the sound, when emitted in front, radiates spherically, and it has the exterior spherical surface to support it. The wave has a gradually-diminishing surface to travel upon and radiate from. The surface is of the same shape as the wave, a hand-in-glove combination, so to speak, and provides maximum dispersion of the wave, over a wider spherical angle of radiation, and the ideal is thus accomplished. The ultimate in operation of a loudspeaker and its associated enclosure is attained. v
I claim: p
l. A combination loudspeaker and loudspeaker enclosure comprising a pair of hemispherical shells detachably secured together, a circumferential joining member having grooves on either side thereof receiving the circumferential edges of said shells, an outer wall of said joining member being exposed to decoratively trim said enclosure and to hide said circumferential edges from view, and an inner wall engaging the inner surfaces of said circumferential edges, means for detachably engaging and securing said edges to said joining member, at least one of said shells having an opening therein, a loudspeaker mounted on the inner surface of said shell to about the periphery of said opening and a stand for supporting said shells with said speaker in any desired position.
2. A loudspeaker and loudspeaker enclosure combination as in claim 1 a flat molded shell inner surface adjacent the periphery of said opening, a speaker grille covering said opening, said loudspeaker being mounted on said inner surface, a plurality of apertures spaced about said opening, retaining means inserted through said apertures engaging and retaining said grille and loudspeaker over said opening, said enclosure having an imperforate rear shell confining rear sound waves generated by said speaker within said enclosure to prevent said rear waves affecting front sound Waves generated by said speaker.
3. A loudspeaker and loudspeaker enclosure combinal tion as in claim 1, said joining member being sufliciently flush with the outer surface of said shells to permit rotation thereof, the outer surface of said one of said shells serving as a sound board to angularly disperse front sound waves from said loudspeaker.
References Cited in the file of this patent UNITED STATES PATENTS OTHER REFERENCES Popular Mechanics (publication), July 1956, 145.