US2858899A

US2858899A - High fidelity speaker enclosure system

Info

Publication number: US2858899A
Application number: US595742A
Authority: US
Inventors: Lopez-Henriquez Miguel
Original assignee: Individual
Current assignee: Individual
Priority date: 1956-07-03
Filing date: 1956-07-03
Publication date: 1958-11-04
Anticipated expiration: 1975-11-04

Description

M. LoPEz-HENRlQUEz 2,858,899

HIGH FIDELITY SPEAKER ENCLSURE SYSTEM Nov. 4, 1958 i'led `July 5, 195e f4, mi f nited States Patent HIGH FIDELITY SPEAKER ENCLOSURE SYSTEM Miguel Lopez-Henriquemronx, N. Y.

Application July 3, 1956, Serial No. 595,742

8 Claims. (Cl. 181-31) The present invention relates to speaker systems and particularly to speaker enclosures for audio systems where high delity is desired.

In the design of a speaker enclosure as well as in the design of the entire fidelity system it is desired to reproduce as nearly as possible the original performance so as to give a sense of presence While many Speaker enclosures have heretofore been designed, they have failed to satisfy this desideratum. One limitation of the usual speaker system is that it is essentially a point source of sound whereas in live performances, such asy orchestral performances, the sound comes from a wide area. It has been proposed to overcome this limitation by the use of two or more speakers located at opposite sides of a room and fed with different signals as in a binaural system or with thesame signal. However, such a system requiring two speakers and two speaker enclosures' isv expensive and occupies too much space for use in any but exceptionally large rooms. It is an object of the invention to overcome this limitation by providing a single speaker enclosure that directs the sound from the speaker in such manner that the sound seems to lill the room and gives an effect closely approaching a live performance.

A further objection to'present speaker enclosures is that the sound heard by a listener is different in different parts of a room. On a line directly in front of the speaker and particularly near the speaker, the higher frequency tones predominate, while in areas on either side of the central line, the highs become weaker and the lows predominate. An explanation of this phenomenon is that the highs emanate from the center of the speaker and travel out in a straight line. On striking Walls, floor or ceiling of a room or objects in a room, they are largely absorbed instead of being reflected. The lows emanate more from the peripheral portions of a speaker and from the rear of the speaker through ports provided in the speaker enclosure and are distributed more to the sides of the room.

It is a further object of the invention t-o overcome this undesirable characteristic and provide a speaker enclosure that blends highs with the lows and distributes both uniformly throughout the room so that sound heardtby a listener will be properly balanced regardless of his position.

In its preferred form, the speaker enclosure in accordance with the invention has the further feature that the blending of highs and lows and the distribution of sound in the room can be readily varied to suit local conditions and individual taste.

Still another feature of the invention is that it permits selective balancing of the lows and highs by varying the speaker opening.

Other objects land advantages of the invention will appear from the following description and claims in conjunction with the accompanying drawings which show by way of example a speaker enclosure in accordance with the invention and in whichr. ICC

Fig. 1 is a front view of a speaker enclosure, portions being broken away to show underlying parts.

Fig. 2 is a horizontal section taken approximately on the line 2--2 in Fig. 1.

Fig. 3 is a vertical section taken approximately on the line 3 3 in Fig. l.

Fig. 4 is a fragmentary section on an enlarged scale, the section being taken approximately on the line 4-4 in Fig. l.

While the novel principles in accordance with the invention are `applicable to speaker enclosures of various types, for example base reflex speaker cabinets, the invention is particularly advantageous when applied to a corner cabinet of the folded horn type and is accordingly shown as being embodied in a cabinet of that type in the accompanying drawings. It will be understood, however, that the invention is in no Way limited to a folded horn or to a corner cabinet.

As illustrated in the drawings, the speaker enclosure in accordance with the invention comprises a cabinet 1 which is completely closed except for a speaker opening 2 and one or more ports 3. The cabinet 1 is shown as a folded horn corner cabinet comprising a top 4, a bot tom 5 and walls extending between the top and bottom. The walls are shown as comprising rear side walls 6 and 7 which meet at an angle of approximately 90 in a rear corner 8. A front-wall 9 has a central portion 9a and side vpanel portions 9b which are disposed at an angle to the central portion and connect the side edges of the central portion with the forward edges of the rear side walls 6 a-nd 7. The walls are joined to one another and to the top and bottom by airtight joints, for example glued tongue and groove joints as shown. The top, bottom and walls of the cabinet are formed from suitable material that is sufficiently thick to inhibit the transmission of sound through it. For example plywood, which is preferably not less than 2% inch thick has been found suitable for this purpose.

The speaker opening 2 is shown located approximately in the center of the central panel 9a of the front wall 9' of the cabinet. It is of suitable shape and size to receive a speaker S which is shown (in broken lines) as being mounted in the opening 2, the speaker being held in place by suitable screws or other securing means (not shown) in usual manner. The speaker is shown as being of the cone type having a c-one S1 and a voice coil S2,V While a speaker of the coaxial type may be used, it is considered preferable to use a single speaker capable of reproducing high, low and intermediate frequencies. The ports 3 are shown as being located in the side panels 9b of the front wall extending substantially from top to bottom Iof the cabinet. The speaker opening 2 and ports 3 are preferably covered with suitable fabric or grill material which readily permits the passage of sound waves.

As the cabinet shown in the drawings is of the folded horn type, baffles 11 and 12 are provided to form the horn The baffles are shown extending rearwardly from opposite sides of the central front panel 9a and converging toward one another. They extend from the front panel toward the rear corner 8 but terminate forwa'rdly of the corner so as to provide a passageway 13 between the rear edge portions of the baffles and passageways 14 between the rear edge portions of the bales and the rear sidewalls 6 and? for the passage of sound Waves. The baffles 11 and 12 preferably extend from top to bottom ofthe cabinet and are joined by strong, tight joints to the top and bottom and to the front wall. They are preferably formed of material having substantially the same characteristics as the walls of the cabinet, for example inch plywood.

In order to provide access to the interior of the speaker enClOSlre for insertion, servicing and removal of the matassa speaker S, the bottom is provided with a removable panel 5a which is of approximately triangular shape and occupies the area between the central panel 9a of the front wall and the baflles 11 and 12. The removable panel 5a is held in place by suitable screws or other securing means 15 and a tight joint between this panel and the remainder of the bottom wall is preferably provided by a gasket 16 of felt, rubber or other suitable material.

Selected areas on the inside of the cabinet 1 are covered with suitable sound absorbing material for example glass fiber matting. The extent and location of such sound absorbing material can be varied according to the characteristics of the cabinet and speaker and the taste of the individual user. In the example shown in `the drawings, glass fiber matting 18 approximately one inch thick is provided on the entire inner surfaces of the baflles 11 and 12, on that portion of the top of the cabinet which is inside the baffles, and on the inner face of the removable bottom panel 5a. The inner face of the front wall, the outer surfaces of the bafes 11 and 12, the inner surfaces of the rear side walls 6 and 7 and the portions of the top and bottom between the baffles and the side walls are left bare.

With the arrangementv shown in the drawings, sound waves F projected from the front of the speaker S pass out through the speaker opening 2. Sound waves R from the rear of the speaker pass rearwardly through the passage 13 between the baffles 11 and 12 and forwardly through the passages 14 between the baffles and the side walls 6 and 7 and out through the ports 3 (Fig. 2). The sound waves R emanating from the ports 3, are for the most part, in a lower range of frequencies, any high frequency waves from the rear of the speaker being largely absorbed by the sound absorbing material 18. The sound waves F from the front of the speaker are both low and high frequencies and higher frequency waves being propagated for the most part from the central portion of the speaker while lower frequency waves emanate from peripheral portions of the speaker.

In accordance with the invention a reflecting surface 20 is provided in fr-ont of the speaker opening 2 and spaced outwardly from the wall of the cabinet in which the speaker opening is provided in order to direct sound Waves from the speaker opening laterally i. e. transversely of the axis of the speaker and toward the ports 3. Thus instead of being projected directly forwardly from the speaker as in the conventional speaker system, the sound waves from the front of the speaker are deilected laterally so as to blend with sound waves emanating from the ports 3. The lateral dellection of the sound waves from the front of the speaker causes these sound waves as well as those from the ports 3 to be distributed substantially uniformly throughout a room in which the speaker system is located so that a person listening to a program will experience the feeling that the sound fills the entire room instead of being projected as a beam from a point source. The resulting effect is much closer to that of a live performance than is possible with conventional speaker enclosure systems.

In the embodiment of the invention illustrated in the drawing, the deflecting surface 20 is provided by

panels

21 and 22 which are connected to one another by a piano hinge 23. The

panels

21 and 22 are conveniently supported by an extension 24 of the top 4 of the cabinet and a similar extension 25 of the bottom 5. As will be seen from Fig. 2, the extensions are of trapezoidal shape. The

panels

21 and 22 extend between the top and

bottom extensions

24 and 25 and the hinge pin 26 of the hinge 23 extends into suitable holes or recesses provided in the top and bottom extensions. The

panels

21 and 22 are thereby held between the top and

bottoml extension

24 and 25 but are swingable about the hinge pin 26 so that they can be disposed at different angles. Strips 27 of felt, rubber or other suitable material are preferably provided on the upper and lower edges of the

panels

21 and 22 so as to hold the panels frictionally in the position to which they have been adjusted and prevent any rattling. A compression spring 28 surrounding the hinge pin 26 and acting between the top extension 24 and the hinge 23 may also be provided to hold the hinged panels frictionally in adjusted position.

The

panels

21 and 22 providing the deecting surface 20 are preferably disposed at an obtuse angle to one another so that the deecting surface 20 is V-shaped with the vertex of the dihedral angle of the surface extending along a linei. e. the axis of the hinge 23- which is perpendicular to the axis of the speaker S. The angle between the

panels

21 and 22 may be readily varied by swinging the panels about the hinge pin 26. While the

panels

21 and 22 are shown as being symmetrically disposed, it willbe understood that in some conditions an asymmetrical arrangement may be desirable and can readily be obtained. The deecting surface 2i) extends across the full width of the speaker opening and is shown as extending beyond the edges of this -opening so as to cover at least a portion of the space between the speaker opening and the ports 3. It is spaced outwardly from the wall of the speaker so as to permit free passage of the sound waves between the deecting surface 20 and the wall of the speaker cabinet in which the opening 2v is provided. This distance may be varied according to individual characteristics of the desired speaker system. For best results, the distance from the vertex of the V shaped deecting surface 20 to the plane of the wall of the speaker cabinet in which the speaker opening is provided is preferably between 1A and 1/z of the diameter of the speaker opening. The

panels

21 and 22 providing the deecting surface 20 are preferably formed of polished hard Wood or plywood providing a hard polished surface so that sound waves emanating from the front of the speaker-including high frequency wavesare deilected without substantial absorption. The panels should be suiciently heavy to avoid undesirable vibration, for example 3A. inch thick.

A further feature of the invention as illustrated in the drawings is the provision of adjustable shutters 30 by means of which the size and shape of the speaker opening 2 can be adjustably varied. The shutters are shown as

rectangular panels

31 and 32 formed of suitable material such as wood 'or plywood. The

panels

31 and 32 are mounted on the central panel 9a of the front wall of the cabinet so as to be movable toward and from one another so as to cover to a greater or lesser extent peripheral portions of the speaker opening 2. By way of example the

panels

31 and 32 are shown mounted on the front wall of the speaker cabinet by means of bolts or screws 33 (Fig. 4) which extend through holes in the

panels

31 and 32 and through horizontal slots 34 in the cabinet wall 9a. A nut 35 on each of the screws or bolts 33 engages the inner surface of the cabinet wall 9a and has wing portions 36 which extend into the slot 34 so as to prevent the nut from turning. A snap ring 37 set in a suitable annular groove in the inner end portion of the screw 33 prevents the nut from coming off the inner end of the screw. From the construction described, it will be understood that when the screws 33 are loosened, the

panels

31 and 32 can be slid horizontally to a position covering a desired portion of the speaker opening 2. The screws 33 are then tightened to hold the

panels

31 and 32 firmly in place. A layer 38 of felt, rubber or other suitable material is preferably provided on the inner face of each of the

panels

31, 32 to prevent vibration and to assist in holding the panels in position. The material 38 is shown in the form of a peripheral strip extending around the marginal portions of the inner faces of the panels.

As mentioned above, the sound waves from the central portion of the front of speaker S `are of higher frequency whereas sound waves of lower frequency emanate from l peripheral portions of the speaker. By positioning the

panels

31 and 32 so as to cover a portion of the peripheral area of the speaker opening, it is possible to block of a portion of the lower frequency sound waves from the front of the speaker. The sound waves from the front of the speaker passing through the restricted speaker opening are thus preponderately higher frequency waves since a portion of the lower frequency waves is blocked olf by the

shutter panels

31 and 32. By adjusting the position of the

panels

31 and 32 it is possible to obtain a desired balance between lower frequency and higher frequency waves. The

shutter panels

31 and 32 and the deecting surface 20 thus cooperate to obtain a balance of highs and lows, to blend the highs and lows together and to distribute the blended sound substantially uniformly throughout the room in which the speaker system is located.

While a preferred embodiment of my invention has been shown in the drawings and particularly described, it will be understood that the invention is in no way limited to this embodiment but may be varied as to form and dimensions within the scope of the appended claims.

What I claim and desire to secure by Letters Patent is:

1. A high fidelity speaker enclosure comprising a cabinet having a top, a bottom and walls extending between said top and bottom, one of said walls having an opening to receive a speaker mounted in said opening and ports spaced laterally from said opening, said cabinet being closed except for said speaker opening and ports, baffles in said cabinet extending inwardly from said one wall between said speaker opening and ports, and means providing a deflecting surface in front of said speaker opening and spaced forwardly from said one wall, said deflecting surface extending transversely of the speaker axis from the central plane of said opening toward said ports to deflect forwardly projected sound waves laterally from the axis of said speaker and blend them with rearwardly projected sound Waves emanating from said ports.

2. A high fidelity speaker enclosure comprising a cabinet having a top, a bottom, a front wall and two side walls extending rearwardly from opposite sides of said front Wall and converging in an approximately ninety degree corner, said front wall having an opening to receive a speaker mounted therein, said opening being approximately midway between said opposite sides of said front wall, means defining ports at opposite sides of said front Wall, said ports being spaced laterally from said speaker opening, a pair of baiies disposed on opposite sides of said speaker opening and extending between said top and bottom and rearwardly from said front wall toward said corner, sound waves from the front of said speaker being projected forwardly from said opening and sound projected from the rear of said speaker travelling rearwardly between said baffles and then forwardly between said balies and side walls and out through said ports and means providing a deilecting surface in front of said speaker opening and spaced outwardly from said front wall, said deecting surface extending laterally to- 6 ward said ports to deect forwardly projected sound waves laterally so as to blend said forwardly projected Waves with the rearwardly projected waves and distribute the combined waves throughout a room in which said speaker enclosure is located.

3. A high fidelity speaker enclosure according to claim 2, in which said dellecting means comprises a flat V- shaped deector having the vertex of the V toward the speaker opening and defining deflecting surfaces that extend laterally and forwardly.

4. A high delity speaker enclosure according to claim 3, in which said deilecting means comprises two deflecting boards hingedly joined to one another along a line in front of said speaker opening and swingable about said hinge line to adjust the angle of said V.

5. A high fidelity enclosure according to claim 2, in which said top and bottom project forwardly of said front wall and in which said deflecting means extends between and is carried by the forwardly projecting portions of said top and bottom.

6. A high fidelity speaker enclosure according to claim 2, in which means is provided for adjustably varying the area of said speaker opening.

7. A high fidelity speaker enclosure according to claim 6, in which said means for varying the area of the speaker opening comprises panels mounted on said front wall and adjacent said speaker opening and movable laterally to cover side portions of said opening to a selected extent.

8. A high fidelity speaker enclosure comprising a cabinet which is completely closed except for an opening to receive a speaker mounted therein and ports spaced from said speaker opening, a pair of shutters slidably mounted on the cabinet adjacent the speaker opening and movable toward and away from one another to block off selected peripheral portions of said speaker opening, sound waves from the front of a speaker mounted in said opening being projected forwardly from said opening and sound waves from the rear of said speaker being projected through said ports, and means providing a deflecting surface disposed in front of said speaker opening and spaced from said cabinet, said deflecting surface being of greater area than said opening and covering said opening and the adjacent portions of said cabinet between said opening and said ports so as to deflect sound waves emanating from said opening and direct them laterally in front of said port.

References Cited in the le of this patent UNITED STATES PATENTS 1,865,735 Wolif July 5, 1935 2,020,166 Swinyard Nov. 5, 1935 2,034,014 Wheeler et al. Mar. 17, 1936 2,050,575 Krause Aug. 11, 1936 2,491,982 Kincart Dec. 20, 1949 2,694,463 Robbins et al Nov. 16, 1954 2,731,101 Klipsch Jan. 17, 1956 FOREIGN PATENTS 695,239 France Sept. 29, 1930