US3247926A

US3247926A - Loud-speaker enclosure

Info

Publication number: US3247926A
Application number: US396023A
Authority: US
Inventors: Edward H Metros
Original assignee: Individual
Current assignee: Individual
Priority date: 1964-09-14
Filing date: 1964-09-14
Publication date: 1966-04-26
Anticipated expiration: 1983-04-26

Description

April 26, 1966 E. H. METROS LOUD-SPEAKER ENCLOSURE Filed Sept. 14, 1964 INVENTOR.

EDWARD H. METROS ATTORNEY Las United States yPatent O 3,247,926 LOUD-SPEAKER ENCLOSURE Edward H. Metros, Uniontown, Pa., assignor of fortyeight one-hundredths interest to Edwin G. Warman, Uniontown, Pa. l

Filed Sept. 14, 1964, Ser. No. 396,023 Claims. (Cl. 181-431) This invention relates generally to the field of sound tranducer equipment, and more particularly to improvements in enclosure apparatus for loud-speakers of the cone type which are utilized for the reproduction of music, speech or other audio intelligence.

As an overall object, the present invention seeks to provide sound reproducing apparatus of an improved type adapted to give quality reproduction performance at moderate cost.

It has been found that extremely realistic and pleasing sound reproduction performance can be achieved when a low-cost, small-size speaker, for example, a speaker having an eight-inch cone diameter, is enclosed in a speaker enclosure constructed in accordance with the principles of the present invention. This is accomplished without the conventional use of additional speakers or tweeters.

Accordingly, it is a further object of the present invention to provide a speaker enclosure of improved design for use with conventional loud-speakers of any size, but particularly adapted for improving the overall performance which may be obtained from loud-speakers of the smaller sizes now seldom considered even usable for overall frequency reproduction in high fidelity systems.

Another object of the present invention is to provide a speaker enclosure of improved design which is relatively inexpensive to manufacture and therefore bringing within the means of the average listener a sound reproducing syste-m having high quality performance.

Still another object of the present invention is to provide a speaker enclosure having a novel internal construction which eliminates substantially all of the hum or reverberation normally associated with enclosures of this type.

Still another object of the present invention is to provide an improved loud-speaker enclosure having a novel internal construction which increases considerably the operating etliciency of the loud-speaker it encloses, especially in the low-frequency ranges.

A further object of the present invention is to provide a speaker enclosure having a novel internal configuration which cancels the undesired sound vibrations which are projected rearwardly of the speaker.

In accordance with the present invention, a casing is provided which is generally parallelepipedal in shape which is completely closed with the exception of a speaker opening provided `in the front wall thereof. Within the casing there is provided a plurality of interconnected chambers defined by partition members of a predetermined construction which cooperate to absorb and thereby cancel the unwanted Isound waves projected rearwardly of the speaker cone. The casing of the present speaker enclosure is adaptable for construction from materials having hard walls and for construction in attractive nonsymmetrically shaped cabinets. Furthermore, the casing as well as the partition members therewithin may be formed from relatively inexpensive materials whereby the overall cost of the present speaker enclosure is considerably below the cost of conventional speaker and speaker enclosure combinations achieving a sound reproduction performance comparable to that of the speaker enclosure of the present invention.

Housed within the present speaker enclosure is one ice low-cost cone-type speaker. The particular arrangement of the partition members provided within the present casing cooperates to improve the reproduction qualities of the moderate cost speaker to such an extent that the results are comparable to, if not better than, loud-speakers of almost twice the size and several times that cost housed in ordinary enclosures.

The above and other objects and advantages of the present invention will become apparent from the following detailed description by reference to the accompanying drawings, in which:l Y

FIGURE 1 is an overall isometric view of the speaker enclosure of the present invention;

FIG. 2 is a cross-sectional view taken along the line II-II of FIG. 3;

FIG. 3 is a cross-sectional View taken along the line III- III of FIG. 2;

FIG. 4 is a cross-sectional view taken along the line IVIV of FIG. 2; and

FIG. 5 is a fragmentary isometric view further illustrating the internal construction of the present speaker enclosure.

Referring now to FIG. 1, there is illustrated a speaker enclosure, generally indicated by the numeral 10, which is generally parallelepipedal and having a front wall 12 and a rear wall 14 (not shown) which are maintained in spaced parallel relation by means of side walls 16 and top and

bottom walls

18, 20. The front wall 12 is provided with a centrally poistioned speaker opening 22 within which rests a cone-type speaker 24. The speaker enclosure or casing 10 is completely closed with the exception of the speaker opening 22. The casing 10 may be formed from any suitable cabinet-making materials, such as seasoned wood, plywood, and the plastic materials available today.

Within the interior of the casing 10 there is provided a first sound absorbing partition 26 which divides the interior of the casing 10 into a rst inner chamber 28 and a peripheral chamber 30 surrounding the first inner chamber 28. The first sound absorbing partition 26 comprises wall members 32 which are connected and provide a continuous partition. Each ofthe Wall members 32 is secured along one edge to the front wall 12 and projects therefrom parallel with and spaced from the corresponding lone of the side walls 16, the top wall 18 and the bottom wall 20 of the casing 10. As can best be seen in FIGS. 2, 4 and 5, the rst partition 26 terminates at a peripheral edge 34 which is spaced from the rear wall 14 so as to define a peripheral passageway 36 providing communication between the peripheral chamber 30 and the first inner chamber 28. A support block 38 is interposed between each wall member 32 and the corresponding casing wall for supporting the rearward end of the wall members 32 against sagging.

The wall members 32 preferably comprise a homogeneous wood-liber board derived from the repulping of No. l grade news stock, to which is added waterproofing ingredients. Material of this type is sold under the trade name of Homasote. Each of the wall members 32 has a plurality of uniformly spaced apertures 40 which increased their sound absorption.

Disposed within the first inner chamber 28 is a second sound absorbing partition 42 which is secured to and projectsV rearwardly of the front wall 12. The second sound absorbing partition 42 defines -a second inner chamber 44 within which is housed the speaker 24. The second sound absorbing partition 42 preferably comprises an elongated semicylindrical shell which extends parallel with the long dimension of the rectangular front wall 12 and opens toward the front wall 12. Hence, the second inner chamber is ibounded by the semicylindrical inner surface 48 of the shell 46 and that inner surface portion 50 of the front wall 12 extending between the upper and lower edges of the shell 46. The speaker opening 22 is preferably located centrally of the inner surface portion 50 thereby also positioning the speaker 24 centrally within the second inner chamber 44.

The semicylindrical shell 46 is provided with a plurality of radially disposed, large diameter apertures 52 and a plurality of radially disposed small diameter apertures 54. As can best be seen in FIGS. 3 and 4, the apertures provided in the semicyclindrical shell 46 are alternately large and small, this is, first a row of large apertures 52, then a row of small apertures 54 and so on along the length of the elongated semicylindrical shell 46. The semicylindrical shell 46 preferably is formed from wood. Alternatively, the semicylindrical shell 46 may be formed from concrete. The semicylindrical shell 46 is open at its opposite ends to provide for communication between the first inner chamber 28 and the second inner charnber 44.

The second partition 42 presents a curved face or an infinite number of non-parallel surfaces to the rear face of the speaker 24. The rearwardly moving sound vibrations emanating from the speaker 24 will impinge the semicylindrical inner surface 4S of the shell 46 and be partially absorbed through the

apertures

52, 54 and partially reflected. The curvatureof the shell 46 reduces to a considerable degree the amount of reflected sound pressures impinging directly or obliquely upon the rear face of the speaker cone. As is known, these reflected sound pressures if permitted to impinge upon the speaker cone would result in a serve dip in the output of the speaker at certain frequencies-this phenomenon is commonly known as choking. However, because of the curved inner surface 4S of the shell 46, a major portion of the rearwardly moving sound vibrations are reflected away from the speaker cone or partially absorbed through the

apertures

52, 54.

Referring to FIG. 4, once the reflected sound waves have entered the first inner chamber 28, they are substantially entirely prevented from re-entering the second inner chamber 44 to impinge on the cone of the speaker 24. Furthermore, the reflected sound waves projected into the first inner chamber Z3 are rapidly absorbed by means of the second sound absorbing partition 26. lt should be noted, in FIG. 4, that the rear wall 14 of the casing is not provided with a sound absorbing surface material as is customary. The conventional sound absorbing material is not required in the present casing 10 since the second partition 42 is interposed between any sound waves which will reflect from the rear wall 14 toward the speaker 24.

The volume of an enclosure housing a typical eightinch speaker should be at least three and one-half cubic feet in order, for example, to prevent the stiffness of the enclosure from raising the loud-speakers resonant frequency by more than 10%. Hence, certain rangesV of proportions have been found critical, if the unexpectedly desirable results of the invention are to be fully achieved. These ranges of proportions may be defined as including constructions in which the lateral dimension of the front wall 12 running generally perpendicular to the shell 46, i.e., the height of front wall 12 (as viewed in FIG. 1), is between about 50% and 60% of the other dimension of such front wall 12 running parallel to the shell 46, i.e., the width of front wall 12 (as viewed in FIG. 1), and in which the distance between the front wall 12 and rear wall 14 is between about 55% and 65% of the last-mentioned other dimension of the front Wall 12. It is to be understood at this time that the present speaker enclosure 10 operates equally as well when positioned horizontally and vrests on either of the walls 18, or when the present speaker enclosure 1t) is turned so that it rests on either of the side walls 16. Various volume relationships exist in the Ipresent speaker enclosure, wherein the present speaker enclosure is characterized by having a volume relationship in which the total volume of the casing 10 and the total volume of the first inner chamber are in the approximate ratio of :72. The present speaker enclosure 10 is further characterized by-having a volume relationship in which the total volume of the first inner chamber and the total volume of the second inner chamber are in the approximate ratio of 100:23. The speaker enclosure 10 is further characterized by having an additional volume relationship in which the total volumes of the casing 10, the first inner chamber ZS and the second -inner chamber 44 are in the approximate ratio of 100:72:l7. The above quoted volume relationships are further defined by stating that the casing 10 and the first partition member 28 are generally parallelepipedal and the second partition member 42, defining the second inner chamber 44, comprises an elongated semicylindrical shell.

Certain dimensional relationships characterize the present speaker enclosure 10. For example, the diameter of the speaker enclosed and the height, width and depth of the casing should ybe in the approximate ratio of 100:200:330:190. Further, the diameter of the speaker enclosed, and the length and diameter of the shell 46 should be in the approximate ratio of 100: 145:255. Still further, the diameter of the speaker enclosed and the width, height and depth of the first partition 26 should be in the approximate ratio of 100:290:165:l85.

As an illustrative example, a speaker enclosure was constructed in accordance with the above recited dimensional relationships and volume relationships in which a low-cost cone-type speaker having an eight-inch cone diameter was enclosed. The dimensions of this enclosure which was found very satisfactory in operation and capable of attaining the markedly improved results characterizing the invention were as follows: The casing 10 had a height of 16.125 inches, a width of 26.5 inches and a depth of 15.25 inches; the first partition 26 had a height of 13.125 inches, a width of 23.5 inches and a depth (measured from the front wall to the peripheral edge 34) of 14.75 inches; and the second partition 42 (the Semicylindrical shell 46) lhad a diameter of 11.5 inches and a length of 20.5 inches. It should be noted that all of the reference dimensions, the proportions thereof, and those mentioned in the claims that follow, refer to the inner dimensions of the

casing walls

12, 14 and 16; the inner dimensions of the lirst partition wall members 32; and the inner dimensions of the semicylindrical shell 46. The apertures 40 in the wall members 32 were formed on twoinch square pattern and were one-quarter inch in diameter. The

apertures

52, 54 in the second partition member were one-quarter and one-sixteenth inch in dia-meter, respectively.

Although the invention has been shown in connection with a certain specific embodiment, it will be readily apparent to those skilled in the art that various changes in form and arrangement of parts may be made to suit requirements without departing from the spirit and scope of the invention.

I claim as my invention:

1. In a speaker enclosure for cancelling rearwardly moving sound vibrations, the combination comprising: a casing having a front wall and a rear wall connected by side walls and top and bottom walls; a first sound absorbing partition projecting rearwardly from said front wall, said first partition dividing the interior of said casing into a first inner chamber and a peripheral chamber which surrounds said first inner chamber and communicates therewith; and a second partition interposed between said front wall and said rear wall, said second partition defining a second inner chamber which is open at its opposite ends to provide communication between said first inner chamber and said second inner chamber.

2. In a speaker enclosure for cancelling rearwardly moving sound vibrations, the combination comprising: a

casing having a front wall and a rear wall connected by side walls and top and bottom walls; first sound absorbing partition means projecting rearwardly of said front wall for dividing the interior of said casing into a iirst inner chamber and a peripheral chamber, said first partition means terminating along a peripheral edge which is spaced from said rear wall to provide communication betweeen said first inner chamber and said peripheral chamber; and second partition means projecting from said front wall for defining a second inner chamber within said first inner chamber, said second partition member comprising an elongated shell which is open at its opposite ends to provide communication between said first and second inner chambers.

3. The combination of claim 1 wherein said speaker enclosure is characterized by having a dimensional relationship in which the diameter of the speaker enclosed thereby and the height, width and depth of said casing are in the approximate ratio of l00:200:330: 190.

4. The combination of claim 1 wherein said second partition member comprises an elongated semicylindrical shell opening toward and secured lto said front wall.

5. The combination of claim 4 wherein said second partition is formed from Wood.

6. The combination of claim 4 wherein said semicylindrical shell has a plurality of apertures therein which are disposed at uniformly spaced points and are alternately of large and small diameter.

7. The combination of claim 4 wherein said shell is characterized by having a dimensional relationship in which the diameter of the speaker enclosed thereby, and the length and diameter of said shell are in the approximate ratio of l00:l45:255.

8. The combination of claim 4 wherein said front wall includes a speaker opening adapted to receive a speaker, which is disposed within said second inner chamber and centrally of said second partition member.

9. The combination of claim 1 wherein said iirst partition member comprises connected side walls each of which is secured along one edge to said front wall and each projecting therefrom substantially parallel with and spaced from the corresponding one of the walls of said casing.

10. The combination of claim 9 wherein said first partition member is formed from a homogeneous, wood-ber board.

11. The combination of claim 9 wherein said casing is generally parallelepipedal and said speaker enclosure is characterized by having a volume relationship in which the total volumes of said casing and said first inner chamber are in the approximate ratio of 100:72.

12. The combination of claim 1 wherein said casing and said first partition means are generally parallelepipedal and said second partition member is an elongated semicylindrical shell opening toward and secured to said front wall.

13. The combination of claim 12 wherein said speaker enclosure is characterized by having a volume relationship in which the total volumes of said casing, said rst inner chamber and said second inner chamber are in the approximate ratio of l00:72:17.

14. In combination with a speaker having a vibratory sound producing member characterized by the projection of desired sound waves from one side thereof and the projection of undesired sound waves from'the other side thereof: a casing having a front wall provided with a speaker opening and a rear Wall which is connected with said front wall by a plurality of connected side walls, said casing being completely closed except for said speaker opening; a iirst apertured partition member projecting rearwardly from said front wall and terminating at a peripheral edge which is spaced from said rear wall, said first partition member dividing the interior of said casing into a iirst inner chamber containing said speaker opening and a peripheral chamber which surrounds said inner chamber and communicates therewith at said peripheral edge; a second apertured partition member projecting rearwardly from -said front wall and residing within said iirst chamber, said second partition member dening a second inner chamber, said second partition memberbeing open at its opposite ends to provide communication between said iirst inner chamber .and said second inner chamber; and means mounting said speaker within said second inner chamber With the -side of said vibratory sound producing member from which the desired sound waves are projected facing said speaker opening and the opposite side thereof disposed inwardly of said second partition member.

15. In combination with a speaker having a vibratory sound producing member characterized by the projection of desired sound waves from one side thereof and the projection of undesired sound waves from the other side thereof: a casing having a front wall provided with a speaker opening and a rear wall connected with said front wall by means of a plurality of connected side walls, said casingbeing completely closed except for said speaker opening; a first partition member comprising a plurality of interconnected side walls each of which is secured along one edge to said front wall and each of which projects rom said front wall substantially parallel with and spaced from the corresponding one of the side walls of saidcasing and all of which terminate along a peripheral edge which is spaced from said rear wall, said tirst partition member dividing said casing into a first inner chamber and a peripheral chamber which surrounds said rst inner chamber and communicates therewith at said peripheral edge, said first partition member having a plurality of apertures in each of its side walls providing sound absorbing characteristics thereof; a second par tition member comprising an elongated semicyclindrical shell opening toward and secured to said front wall, said second partition member extending transversely of said speaker opening to dene a second inner chamber, said second partition member being open at each of its ends and terminating along an arcuate edge which is spaced from one of the side walls of said iirst partition member to provide communication between said rst inner chamber and said second inner chamber, said second partition member having a plurality of apertures formed therein which renders said second partition member sound absorbing; and means mounting said speaker within said secondinner chamber with the side of said vibratory sound producing member from which the desired sound waves are projected facing said opening and the opposite side thereof disposed inwardly of said second inner chamber.

References Cited by the Examiner UNITED STATES PATENTS 2,337,213 12/1943 Topping 1Sl3l 3,142,353 7/1964 Todisco 181--31 FOREIGN PATENTS 557,850 9/l932 Germany.

467,279 6/ 1937 Great Britain. 729,204 5 1955 Great Britain. 903,995 8/ 1962 Great Britain.

LEO SMILOW, Primary Examiner.

STEPHEN I TOMSKY, Examiner.