Adjustable speaker cabinet

A cabinet for improving the sound output of an amplifier, the cabinet being in the form of an upright rectangular housing with a horizontal partition dividing the interior into an upper and lower portion, the partition having a speaker opening and a baffle opening, a speaker being mounted in the speaker opening for upward projection of the sound into the housing upper portion, the speaker being connected to the amplifier, a sounding board within the housing upper portion inclined at an angle from the housing rear upwardly towards the housing front, a sheet of metal affixed to the horizontal partition and covering the baffle opening, the vibration of the speaker serving to drive the metal baffle by condensations and rarefaction of the sound waves to either side of the horizontal partition so that the metal baffle functions as a supplemental and complementary sound source.

BACKGROUND AND OBJECTS OF THE INVENTION 
The conversion of an electrical signal into an audio signal requires a 
speaker in the form of a diaphragm having a coil affixed thereto in a 
magnetic field, the electrical signal being used to oscillate the 
diaphragm. The compression and rarefaction of the air surrounding the 
speaker is easily short-circuited back and forth around the edges of the 
speaker, therefore, to achieve good sound transmission a speaker cabinet 
is required. A good speaker cabinet refines the tonal quality of the sound 
produced by the speaker. 
For background information as to types of speaker cabinets which provide 
improved speaker performance refer to my prior issued U.S. Pat. No. 
3,777,844, entitled "ADJUSTABLE SPEAKER CABINET", issued Dec. 11, 1973, 
and to my U.S. application Ser. No. 617,046, entitled, "CABINET FOR 
IMPROVING THE SOUND OUTPUT OF AN AMPLIFIER," filed Sept. 26, 1975 now U.S. 
Pat. No. 3,980,154. 
It is an object of this invention to provide an improved cabinet for a 
speaker. 
More particularly, an object of this invention is to provide an improved 
speaker cabinet of upright rectangular construction having an inner 
horizontal partition dividing the interior of the cabinet into an upper 
and lower portion and having an opening in the partition in which the 
speaker is mounted for projecting sound upwardly into the upper portion, 
and having a second opening covered by a baffle plate, the baffle plate 
acting in response to the condensation and rarefactions of the air to 
either side of the baffle plate as imposed by the actuation of the speaker 
to function as a supplemental sound producing apparatus. 
It is another object of this invention to provide various sound 
conditioning devices and apparatus which may be utilized with the basic 
cabinet to selectively tune the sound produced in the cabinet to enable 
the individual to customize the speaker cabinet to his preselected sound 
preference. 
Another object of this invention is to provide a sound lens for use in a 
speaker cabinet for transmitting sound from one part of the cabinet to 
another or for transmitting sound from the interior to the exterior of the 
cabinet. 
These and other objects and a better understanding of the invention will be 
had by reference to the description and claims taken in conjunction with 
the drawings.

SUMMARY OF THE INVENTION 
A cabinet for improving the sound output of an amplifier is disclosed, the 
cabinet being in the form of an upright rectangular housing having an 
intermediate horizontal partition dividing the interior of the housing 
into an upper and lower portion. The horizontal partition has a speaker 
opening and at least one baffle opening, the speaker and baffle openings 
being spaced apart from each other. A speaker is mounted to the partition 
in the speaker opening and oriented to direct sound upwardly from the 
lower to the upper portion of the speaker cabinet interior, and each 
baffle opening has a metal baffle plate thereacross, the baffle plate 
functioning to vibrate in response to the sound wave condensations and 
rarefactions produced by the speaker and to thereby generate sound. The 
upper portion of the cabinet interior has a sounding board sloping from 
the lower back to the upper front so that sound produced by the speaker 
and the baffle plate or sound lens is reflected off the sounding board and 
through the upper front portion of the speaker cabinet which has openings 
therein for sound passage. An important novel aspect of the speaker 
cabinet is the incorporation of one or more baffle plates in the 
horizontal partition to supplement and augment the sound produced by the 
speaker. Further, a variety of devices are provided which may be utilized 
to change the sound characteristics of the speaker cabinet and 
particularly sound produced by the baffle plate to enable the user to 
selectably arrange the specific characteristics of the sound to suit his 
individual taste. 
DETAILED DESCRIPTION 
Referring now to the drawings and first to FIGS. 1A, 1B, 2, 3 and 4, a 
speaker cabinet which incorporates the principles of this invention is 
generally indicated by the numeral 10. The cabinet 10 is of rectangular 
upright construction, including a front 12, a rear 14, side wals 16 and 
18, a bottom 20 and top 22. 
Within the interior of cabinet 10 is a horizontal partition 24 which 
divides the interior of the cabinet into an upper and lower chamber. The 
lower chamber 26 is closed on the bottom, front and sides, and, as shown 
in the rear view of FIG. 2, has openings 28 in the lower portion 14A of 
the rear panel. The total area of openings 28 in rear lower panel 14A 
should not exceed the horizontal area of the speaker which will be 
described subsequently. 
The upper chamber of cabinet 10 is divided into a forward portion 30 and a 
rearward portion 32 by a sounding board 34. The sounding board is 
positioned to extend from the rearward lower portion of the cabinet upper 
chamber to the upper forward portion at an angle A as shown in FIG. 4 of 
between about 30.degree. to 70.degree. relative to the horizontal position 
24. 
Formed in the horizontal partition 24 is a speaker opening 36 (See FIG. 3). 
Attached to the lower surface of sounding board 24 is a speaker 38 (See 
FIG. 4) which, when energized by an amplifier, directs sound upwardly 
through the opening 36 into the upper interior portion of the cabinet 
where the sound impinges upon the sounding board 34 and is reflected 
outwardly through the upper portion of front panel 12. 
Formed in the horizontal partition 24 are one or more baffle openings 40. 
At least one baffle opening 40 is required to practice the invention. Two 
openings 40 are preferred; however, more than two may also be employed. 
The baffle openings are spaced away from the speaker opening 36 and are 
preferably dimensioned to provide a total of less than one-fourth the area 
of the speaker opening. Covering baffle opening 40 is a baffle plate 42 
supported to the horizontal partition 24 by means such as bolts 44 and 
nuts 46. Baffle plates 42 are preferably of metal, such as aluminum or 
steel, and preferably of about 14 gauge thickness. 
The cabinet lower chamber 26 may be provided, as illustrated in FIG. 4, 
with a horizontal baffle board 48 having openings 50 therein; however, the 
use of the lower baffle board 48 is optional. 
The portion of the cabinet front cover 12 is provided with a number of 
openings 52 as shown in FIG. 1A by which sound emanates from the cabinet. 
The size, variety, and arrangement of the openings 52 may vary. FIG. 1B 
shows an alternate embodiment in which at least a portion of the openings 
are noncircular, such as elongated openings 54. The front panel, and 
particularly the upper portion thereof, may be formed of plywood or 
plastic to easily facilitate the provisiion of openings 52 and 54. Wave 
guide tubes 56 may be inserted in some of the openings 52 in the front 
panel 12 and held in place, such as by nuts 58 (See FIG. 4). The purpose 
and function of the wave guide tubes 56 is described in my U.S. Pat. No. 
3,777,844. 
Important features of this invention are the provision of the baffle 
openings 40 and baffle plates 42 of thin metal affixed over opening 40 in 
the partition 24. Since the speaker 38 is mounted to partition 24, it 
exerts in response to an electrical signal successive condensations and 
rarefactions of the air to either side of the partition. These pressure 
differentials act on each baffle plate 42 and cause it to displace. This 
displacement produces sound waves which are reflected by the sound board 
34 outwardly through the speaker front panel 12. Baffle plates 42 are 
sound generating devices which are not connected electrically to an 
amplifier. Each of the baffle plates 42 becomes a speaker, since the sound 
waves or sound phase emanating from the speaker made a 180.degree. turn in 
the lower chamber 26 and enters the upper chamber 30 through the baffle 42 
as the condensations and rarefactions due to the to-and-fro action of the 
baffle plates. 
Baffle openings 40 and plates 42 may be of any configuration, however, are 
preferably of hexagonal or circular shape, and the total area of the 
baffle openings 40, whether one, two or more openings are employed, and as 
above indicated, should not exceed about one-fourth the vibrational area 
of speaker 38. 
The sound emanating by baffle plates 42 may travel upwardly and impinge on 
sounding board 34 and be reflected thereby outwardly through the openings 
52 and 54 in front plate 12, or the sound generated by the baffle plates 
may be otherwise treated by devices illustrated in FIGS. 5 through 11B. 
FIG. 5 illustrates another important feature of this invention--a device 
which is termed a wave guide sound lens 60. The sound lens 60 is a 
metallic tubular member with a closed end 60A. The cylindrical exterior is 
threaded at 60B, and the device is mounted in baffle opening 40 by means 
of large nuts 61. Resilient gaskets 62 prevent against extraneous sound 
leakage. 
The closed end 60A of the sound lens is meniscus shaped or concave-convex 
in cross-section, as shown. The interior surface is concave, and the 
exterior surface is convex, with radii of curvature selected so that the 
center portion, which is at the tubular axis, is very thin, while the 
outer portion thickens to equal the wall thickness of the tubular wave 
guide sound 60, or the maximum thickness may be greater than the wall 
thickness. 
The sound wave guide lens of FIG. 5 transmits the sound passing through the 
opening 40 in partition 24, and diffuses the sound upwardly against the 
inclined sounding board 34 where it is reflected outwardly through the 
speaker front openings. 
Another way of using the sound wave guide lens of FIG. 5 is illustrated in 
FIG. 1A. The sound lens 60 is mounted in the lower portion of the front 
panel 12. In this arrangement, sound passes directly through the lens to 
the front exterior of the speaker. The lens diffuses and spreads the sound 
as it emanates from the speaker cabinet. While the sound lens 60 is shown 
in the center of the speaker it may be displaced to one side or the other, 
and may be located nearer bottom 20 or the partition 24 (not seen in FIG. 
1A). 
FIG. 6 shows an alternate embodiment of the sound lens. In this 
arrangement, a metallic ring body 63 is of a diameter to mount in opening 
40 in partition 24. O-rings 64 may be used in the outer cylindrical 
surface 63A to prevent sound leakage. The ring 63 seats against baffle 
plate 42. 
The upper surface 63C of ring 63 is frusto-conical in configuration, 
tapering to a reduced diameter central axial opening 63B. Combined with 
baffle plate 42, ring 63 forms an acoustical lens which spreads the sound 
passing therethrough, the diffused sound impinging on the inclined baffle 
board 34. 
The ring upper surface 63C may be concave rather than conical. In addition, 
plate 42 may be integrally formed with ring 63. It can be seen that the 
acoustical lens as illustrated in FIGS. 5 and 6 may take a variety of 
configurations, all in keeping with the spirit and scope of the invention. 
FIGS. 7A and 7B show another arrangement for treating the sound passing 
through and generated by baffle plate 42. A closed top, open bottom vessel 
66 has a lower external dimension to snugly fit the baffle opening 40. An 
opening 68 intersects a vessel side wall tangentially. A wave guide 70 is 
affixed to the vessel 66 at the opening 68 and directs the sound from 
baffle plate 42 in the preselected direction. The user may orient the 
vessel 66 so that the opened end of the guide tube 70 is directed 
outwardly through an opening in the front panel 12 or rearwardly to 
reflect off the sounding board 34. The vessel 66 is preferably filled with 
steel wool 71 to soften the sound passing therethrough. 
FIGS. 8 and 9 show an alternate embodiment of the arrangement of FIGS. 7A 
and 7B. Vessel 72 is dimensioned so that the lower portion snugly fits 
within the baffle opening 40 but is arranged such that the top 74 has an 
opening 74A having communication with a sound guide tube 76 in the form of 
an elbow, that is, a 90.degree. bend, so that the device may be oriented 
to direct sound forwardly or rearwardly as previously described. 
FIG. 10 shows generally the same arrangement of FIGS. 8 and 9, but wherein 
the sound tube 78 is not curved but extends upwardly with a truncated 
upper opening 80. FIG. 10 also shows the use of steel wool 71 within the 
interior of the vessel 74 to avoid undesirable sound reflections and to 
soften and mute the sound passing into the interior of the sound tube 78. 
Nuts 82 are employed to retain the threaded lower end of the tube 78 into 
opening 74A formed in the top 74 of the vessel. The lower external portion 
of the vessel 74 is provided with a groove 84 receiving an O-ring 86 to 
insure air-tight engagement of the vessel 74 and opening 40 and at the 
same time permit easy rotational orientation as desired by the user. 
FIGS. 11A and 11B shows the use of an alternate arrangement for 
transmission and treatment of sound passing from through partition 24. 
This embodiment employs a sound wave tube 88 which has an external 
diameter to snugly fit opening 40 in partition 24. The sound wave tube 88 
may be supported in opening 40 in a variety of ways, but a preferred 
arrangement is as illustrated, with external threads 88A and large nuts 
90. 
One end 92 of tube 88 is open. The opposite end is truncated at an acute 
angle relative to the tube axis. The truncated end is closed by an 
elliptical plate 94. Plate 94 is of very thin metal to permit the passage 
of sound therethrough and along the interior of the tube. The sound wave 
guide tube can be mounted, as illustrated with open end 92 upward, 
extending into chamber 30, or the closed end may be upperward. The 
elliptical plate 94 functions as baffle plate 42 compared to the 
embodiments previously described. 
The speaker cabinet described provides a unique arrangement wherein baffle 
plates and sound lenses are utilized to function as supplemental speakers, 
that is, sound generating devices which are not electrically connected to 
an amplifier. These sound generating devices augment the sound produced by 
the speaker mounted within the cabinet. A variety of elements are 
illustrated for use to change the characteristics of the sound generated 
within the speaker cabinet and particularly the sounds from the baffle 
plate which, coupled with the use of selectable sound tube guides of 
various lengths and characteristics, enable the user of the speaker to 
customize and tune the speaker cabinet to produce the sound characteristic 
most desirable to himself 
While the invention has been described with a certain degree of 
particularity, it is manifest that many changes may be made in the details 
of construction and the arrangement of components without departing from 
the spirit and scope of this disclosure. It is understood that the 
invention is not limited to the embodiments set forth herein but is to be 
limited only by the scope of the attached claim or claims, including the 
full range of equivalency to which each element thereof is entitled.