US3138220A

US3138220A - High fidelity speaker mounting

Info

Publication number: US3138220A
Application number: US59305A
Authority: US
Inventors: Victor B Glindmeyer
Original assignee: Individual
Current assignee: Individual
Priority date: 1960-09-29
Filing date: 1960-09-29
Publication date: 1964-06-23
Anticipated expiration: 1981-06-23

Description

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. HIGH FIDELITY SPEAKER MOUNTING Filed Sept. 29, 1960 4 Sheets-Sheet 4 ny/wwf @L4 ATTORNEYS United States Patent O 3,138,220 HIGH FIDELITY SPEAKER MOUNTING Victor B. Glindmeyer, 4% S. Wayne St., Arlington, Va. Filed Sept. 29, 196i), Ser. No. 59,305 17 Claims. (Cl. 181-31) The present invention relates to a speaker enclosure for a high fidelity reproduction system. The principal and common function of all enclosures, whether they be horns, bass reflex cabinets, pipes or baffles is to separate the back radiation and front radiation of the loudspeaker cone. This is necessary since the back radiation and front radiation of the cone are 180 out of phase and cancel each other out at low frequencies.

A pipe is an obviously simple and space saving means of separating the front and back radiation. Pipes are rarely used, however, since the air column in the pipe resonates at a frequency dependent upon the size of the pipe and produces peaks in response at this frequency and at harmonics thereof.

With various degrees of success attempts have been made to design pipe enclosures to minimize or eliminate the fundamental pipe resonance, and/or the harmonics thereof. Voight, for example, patented a method of mounting the speaker at a point one third of the way along the length of the pipe. Others, (see for example, Briggs, Sound Reproduction, 3rd Edition 1953) have experimented with tapering pipes or providing the ends of pipe with slots or special shapes.

It is an object of the present invention to provide a pipe enclosure which is so vented that pipe resonances are substantially eliminated, but yet the front and back radiation of the cone are effectively separated.

It is a further object of the present invention to provide a vented pipe type of speaker enclosure which substantially overcomes the drawbacks in prior art types of pipe speaker mountings.

Other and further objects of the present invention will become apparent from the following specification and claims, taken together With the accompanying drawings, in which:

FIG. 1 is a front perspective View of a speaker enclosure according to the present invention;

FIG. 2 is a rear perspective view of the speaker enclosure of FIG. 1;

FIG. 3 is a sectional View of the speaker enclosure of FIGS. 1 and 2 taken along line 3-3 of FIG. 2;

FIG. y4 is a rear perspective view of a modified form of speaker enclosure according to the present invention;

FIG. 5 is a sectional View of the speaker enclosure of FIG. 4 taken along line 5--5 of FIG. 4;

FIG. 6 is a front perspective View of another modified form of speaker enclosure according to the present invention;

FIG. 7 is a rear perspective view of the speaker enclosure of FIG. 6;

FIG. 8 is a rear perspective view of still another modiiied form of speaker enclosure according to the present invention;

FIG. 9 is a rear perspective View of a further modilied form of speaker enclosure according to the present invention;

FIG. 10 is a rear perspective view of a still further modiiied form of speaker enclosure according to the present invention;

FIG. ll is a sectional view of the speaker enclosure of FIG. l0 taken along line 11-11 of FIG. 10;

FIGS. 12-15 are rear perspective views of other modified forms of speaker enclosures according to the present invention.

FIG. 16 is a front perspective View of another modi- 3,138,220 Patented June 23, 1964 "ice ied form of a speaker enclosure according to the present invention; and

FIG. 17 is a rear perspective view of another modified form of a speaker enclosure according to the present invention.

As seen in FIGS. 1-3, the speaker enclosure according to the present invention comprises a pipe 20 having a front panel 21, two said panels 22 and 23, and a bottom 24. A rear panel 25 is provided, which in the embodiment of FIGS. 1-3 is in two parts 25a and 25b spaced from each other to form a passageway in the form of slot S which extends from the closed bottom of the pipe all the way to the open top thereof. The parts 25a and 25b are braced by cross pieces 26 spaced along the height of the pipe, and a cross piece 27 along the bottom 24 at the back thereof.

The front panel 21 has a plurality of openings therein for accommodating speakers. The present embodiment has two

large openings

28 and 29 for larger speakers for reproducing low frequencies, and a third opening 30 for accommodating a so-called mid-range speaker. The number and size of these openings can be varied in any Way affecting the nature of this invention. The front panel may also be braced by crosspiece 21a.

The top of the pipe 20 is open.

The embodiment shown in FIGS. 4 and 5 is the same as that of FIGS. 1-3, except that the cross braces are positioned so as to run from the front panel 21 to the rear panel 25. As seen in the gures, the cross braces 31 extend from the free edges 25e of the rear panel portions 25a and 25b to the front panel 21, there being several pairs of cross braces. The advantage of this construction is that the slot S is completely unobstructed throughout its length.

The embodiment shown in FIGS. 6 and 7 is the same as that of FIGS. 1-3 except that the length of the pipe 209 has been shortened, and only one aperture 289 has been provided in the front panel 219 instead of the three apertures of the embodiment of FIGS. 1-3. Otherwise, the slot S9 extends from the bottom to the top of the pipe, the bottom of vthe pipe being closed by a bottom panel 249 and the top being open. Because the length of the pipe has been reduced, the cross braces may be omitted.

The embodiment of FIG. 8 is very similar to that of FIGS. 13, being an open pipe 209 with front, side, bottom and

rear panels

219, 229, 239, 249, and 259 respectively. The slot S9 in the rear panel 259 however, extends from the bottom to a point which is adjacent to the top of the pipe, rather than all the way to the top as with the embodiment of FIGS. 1-3.

The embodiment of FIG. 9 is very similar to that of FIGS. 1-3, also being an open pipe 209 with front, side, bottom and

rear panels

219, 229, 239, 249, and 259 respectively. Instead of the slot S in the rear panel, however, there is provided three narrow slits, S91., Seb, and 89C. These slits extend from the bottom of the pipe to a point adjacent the top thereof, in the same manner as the single slot S9 of the embodiment of FIG. 8.

The embodiment of FIGS. 10 and 1l is similar to that of FIGS. l-3 insofar as it is an open pipe 2019 having a front panel 2119 with speaker openings therein, and side panels 2219 and 2319 and a bottom 2419 thereon. In the back of the pipe 2019 there is a passageway S19 which is a sinuous passageway defined by the three panel portions 25199, 25199, and 25199. These three panel portions are positioned to form a labyrinth, the passageway being the path through the labyrinth from within the pipe to the space outside the pipe. The two panel portions 2519EL and 2519c are mounted on the side panel 2319 and extend more than one half the distance to the opposite side panel 2219, while amaaao 3 the panel portion 25161, is mounted on the side panel 2216 and extends toward the opposite side panel 2316 and interleaves with the panel portions 25161.l and 25166.

The embodiment of FIG.,12 is very similar to that of FIGS. 1-3, being an open pipe 2012 with front, side, bottom and rear panels V2ll12,.2 l212, 2312, 2412, and 2512, the slot S12 extending all the way from the bottom to the top of the rear panel. Over the slot, however, is a strip 32 of flexible material, such as rubber, which is secured to one of the rear panel portions 25121, by fastening means 33.

The embodiment of FIG. 13 is similar to that of FIG. 12, except thatin place of the flap member 32, there is xed in position over the slot S13 a strip 34 of heavy thick and air pervious material, such as felt.

It will thus be seen that the passageway in the form of the slot S in the rear panel of the embodiments of FIGS. 1-3, FIGS. 4 and 5, FIGS. 6 and 7, FIG. 8 and FIG. 9 are not artificially loaded in that they are unobstructed, the passageways in the rear panels of the embodiments of FIGS. 10 and 11, FIG. l2 and FIG. 13 are artificially loaded, in that the air from Within the pipe must traverse the sinuous passageway in the embodiment of FIGS. 10 and 1l, must move the flap 32 of the embodiment of FIG. 12, and must pass through the heavy felt strip 34 of the embodiment of FIG. 13. The effect of thus restricting the opening in therspeaker enclosure is to further eifect separation of the front and back radiation from the particular speakers mounted thereon.

The embodiments of FIGS. 14 and 15 are very similar to the embodiment of FIGS. 1-3, except for the particular shape of the slots S. In the embodiment of FIG. 14, the slot S14 in the rear panel 251.1 narrows from lthe bottom to the top of the pipe. The edges of the rear panel portions 25141 and 251.11, are straight. In the embodiment of FIG. 15, on the other hand, the slot S16 is also tapered, but in this embodiment the edges of the rear panel portions 2516av and 25151, are curved exponentially.

The embodiment of FIG. 16 is similar to the embodiment of FIG. 1, in that it comprises a pipe having a front panel 2116 and two side panels 2216 and 2316. A rear panel 2516 has the slots S16 extending from the top to the bottom of the panel. Front panel 2116 has two speaker openings 2816 and 2916 therein. The bottom of the pipe is vented by spacing it from a support surface by means of four short legs 4t), the legs spacing the bottom of the pipe from the supporting surface to leave a vent 41 around the entire periphery of the bottom of the pipe. The embodiment of FIG. 17 is similar to that of FIG. 16, except that the bottom of the pipe stands on the supporting surface therefor and the side panel 2317 has a portion cut therefrom along the lower edge to leave a vent 42. A portion of the side panel is left at 43 to brace the corner of the pipe, and braces 44 are provided along the rear of the bottom of the rear panel parts 2517.

The result of venting the open pipe speaker enclosure is to eliminate substantially the undesirable quarter wave fundamental resonances and the accompanying harmonics without detracting from the ability of the pipe to separate the back and front radiation of the speaker cone. Ideally the vent or vents will be large enough to effectively eliminate the resonance of the pipe but small enough to retain a maximum separation of the front and back radiation of the cone. The construction is extremely simple, yet takes up a relatively small oor space as compared to a folded horn or bass reflex type of speaker mounting. An incidental yet highly valuable advantage of the speaker enclosure according to the present invention, is that the high frequency speaker, the so-called tweeter, can be 6 It will of course be understood that the passageway in the enclosure need not be in the rear thereof in relation to the speaker. It may be provided in any other appropriate position.

It is thought that the invention and its advantages will be understood from the foregoing description and it is apparent that various changes may be made in the form, construction and arrangement of the parts without departing from the spirit and scope of the invention or sacrificing its material advantages, the forms hereinbefore described and illustrated in the drawings being merely preferred embodiments thereof.

I claim:

1. A speaker enclosure, comprising an elongated cabinet having a substantially rectangular cross section taken perpendicular to the longitudinal axis of the enclosure, one end of said enclosure being open and the other end being closed, one of the walls of the enclosure having at least one opening therethrough for mounting a speaker, and said enclosure having at least one vent opening in one of the walls of the cabinet, said vent opening extending from the closed end of the enclosure for substantially the full length of the enclosure, said vent opening being sufliciently large to elfectively eliminate the resonance of the enclosure and small enough to retain a maximum separation of the front and back radiation of the speaker.

2. A speaker enclosure as claimed in `claim l in which there are a plurality of vent openings, said Vent openings being in the wall of the cabinet opposite the wall having the speaker mounting opening therein, said vent openings being in the form of slots.

3. A speaker enclosure as claimed in claim 1 in which at least one of the walls of the enclosure hasV an aperture therein along the edge of the wall adjacent the closed end of the enclosure.

4. A speaker enclosure as claimed in claim 3 in which the wall having the aperture along the edge thereof is a wall other than the wall having the vent opening therein.

5. A speaker enclosure as claimed in claim 4 in which each of said Walls has an aperture therein adjacent the closed end of said pipe, said panels having portions thereof remaining at the corners of said pipe forming legs for spacing said pipe from a supporting surface.

6. A speaker enclosure as claimed in claim 1 in which said vent opening is a slot.

7. A speaker enclosure as claimed in claim 6 in which said slot extends the full length of the wall in which the slot is located.

8. A speakerenclosure as claimed in claim V6 in which Said slot extends less than the full length of the wall in which the slot is located.

9. A speaker enclosure as claimed in claim 6 in which Said slot has parallel sides.

10. A speaker enclosure as claimed in claim 6 in which said slot has sides which are straight and which converge toward the open end of said enclosure.

11. A speaker enclosure as claimed in claim 6 in which said slot narrows toward the open end of said enclosure, and said slot has edges which are exponentially curved.

12. A speaker enclosure as claimed in claim 6 in which there are a plurality of speaker openings in said one wall of said enclosure and said slot has parallel sides and extends from the bottom all the way to the open end of said enclosure.

13. A speaker enclosure as claimed in claim 6 in which there is only a single speaker opening in said one wall of said enclosure, and said slot has parallel sides and extends from the bottom all the way to the open end of said enclosure. Y K 1 14. A speaker enclosure as claimed in claim 6 in which said vent opening has a loading means thereacross.

15. A speaker enclosure as claimed in claim 14 in which said loading means is a llap of flexible material secured to the wall in which the slot is located along one edge of said slot.

16. A speaker enclosure as claimed in claim 14 in which said loading means is a heavy thick material pervious to air fixed over the slot.

17. A speaker enclosure as claimed in claim 6 in Which the wall of said enclosure having the slot therein has the parts thereof on opposite sides of said slot offset transversely to the direction of the longitudinal axis of said enclosure and extending past each other, one of the parts being closer to the axis of the enclosure and the other being more remote from the axis, the Wall of the enclosure from which the closer part extends projecting past said closer part, and a further Wall extending from the end of References Cited in the lile of this patent UNITED STATES PATENTS 2,489,653 Leslie Nov. 29, 1947 2,731,101 Klipsch Jan. 17, 1956 2,754,926 Rice July 17, 1956 2,885,024 Jordan May 5, 1959

Claims

1. A SPEAKER ENCLOSURE, COMPRISING AN ELONGATED CABINET HAVING A SUBSTANTIALLY RECTANGULAR CROSS SECTION TAKEN PERPENDICULAR TO THE LONGITUDINAL AXIS OF THE ENCLOSURE, ONE END OF SAID ENCLOSURE BEING OPEN AND THE OTHER END BEING CLOSED, ONE OF THE WALLS OF THE ENCLOSURE HAVING AT LEAST ONE OPENING THERETHROUGH FOR MOUNTING A SPEAKER, AND SAID ENCLOSURE HAVING AT LEAST ONE VENT OPENING IN ONE OF THE WALLS OF THE CABINET, SAID VENT OPENING EXTENDING FROM THE CLOSED END OF THE ENCLOSURE FOR SUBSTANTIALLY THE FULL LENGTH OF THE ENCLOSURE, SAID VENT OPENING BEING SUFFICIENTLY LARGE TO EFFECTIVELY ELIMINATE THE RESONANCE OF THE ENCLOSURE AND SMALL ENOUGH TO RETAIN A MAXIMUM SEPARATION OF THE FRONT AND BACK RADIATION OF THE SPEAKER.