A loudspeaker including a generally spherical cabinet and at least one speaker driver contained in the cabinet and dividing the cabinet into a major sound chamber and a minor sound chamber. The cabinet has at least two sound propagation ports communicating with the major sound chamber and at least two sound propagation ports communicating with the minor sound chamber. The spherical cabinet of the loudspeaker provides an omni-directional radiation pattern. According to one possible embodiment, the at least one speaker driver comprises two speaker drivers facing each other and connected out of electronic phase so as to operate as a single push-pull unit. The loudspeaker, therefore, utilizes the rear sound waves created by its speaker drivers. One of the speaker drivers is substantially contained in the minor sound chamber and the other of the speaker drivers is substantially contained in the major sound chamber. According to another possible embodiment, the loudspeaker further includes at least one support assembly extending through the cabinet and linking opposing hanging points on the outside of the cabinet. The loudspeaker, accordingly, can be hung from above and support weight hung below without requiring that the cabinet itself bear the weight.

FIELD OF THE INVENTION 
The present invention relates to high fidelity voice or music reproduction 
systems, and in particular to loudspeakers for broadcasting announcements, 
music, etc. in large open or enclosed areas. Even more particularly, the 
present invention relates to an omni-directional sub-bass loudspeaker. 
BACKGROUND OF THE INVENTION 
In the field of high fidelity voice or music reproduction systems, and in 
particular loudspeakers, substantial and continuous efforts are being made 
to obtain sound reproduction which is as faithful as possible to the 
original sounds to be reproduced by the loudspeaker. The problem is most 
acute for lower frequency sounds, otherwise known as bass sounds, and most 
loudspeakers fail to faithfully reproduce such bass sounds. Many 
loudspeakers include at least one speaker driver contained in a cabinet, 
which may or may not be used to help direct sound waves from the speaker 
driver. The inherent resonance frequency of the speaker driver and the 
cabinet function to produce "booming" or unnatural emphasis of base tones 
of particular frequencies, while de-emphasizing other frequencies, thereby 
distorting announcements or music broadcast over the loudspeaker. 
Sound distortions created by loudspeakers, however, are most particularly 
acute in large open or enclosed areas such as, for example, stadiums, 
arenas, airports, train stations, theaters, ice rinks or the like. Most 
loudspeakers produce sound in only one direction and, therefore, must be 
aimed towards the audience for all frequencies to be heard. Often, even in 
areas with good acoustic qualities, dead spots, where sound reproduction 
is soft or unintelligible, and hot spots, where sound reproduction is 
uncomfortably high, are created by the loudspeaker. In addition, with most 
loudspeakers it is often difficult to project sound to persons furthest 
from the loudspeakers without making it uncomfortably loud for persons 
nearest the speaker. What would be best is a loudspeaker that provides an 
omni-directional radiation pattern that decreases or eliminates the 
creation of dead and hot spots when broadcasting in large open or enclosed 
areas. 
In general, nearly all speaker drivers reproduce sounds with a vibrating 
diaphragm. As the diaphragm vibrates, sound waves are propagated both in 
front of and behind the speaker driver. The sound waves on opposite sides 
of the speaker driver are 180.degree. out of phase and provision must be 
made to prevent the sound waves from canceling each other out. Normally, 
this is accomplished by mounting the speaker driver in an appropriate 
enclosure or cabinet, which is employed to contain or dissipate the "rear" 
sound wave and permit free radiation of the "front" sound wave. 
Alternatively, the rear sound wave is useful only if it is in phase or 
augments the front sound wave. What would be best is a loudspeaker that is 
adapted to harness the rear sound wave in addition to providing 
omni-directional radiation. 
What is desired, therefore, is a loudspeaker that provides omni-directional 
radiation, especially with low frequencies, that decreases or eliminates 
the creation of dead and hot spots when broadcasting in large open or 
enclosed areas. Preferably, the loudspeaker will utilize the rear sound 
waves created by its speaker drivers. In addition, the loudspeaker should 
have a rigid and durable, yet light-weight cabinet, and still be able to 
be hung from above and support weight hung below. 
SUMMARY OF THE INVENTION 
An object, therefore, of the present invention is to provide a loudspeaker 
that provides an omni-directional radiation pattern, especially with low 
frequencies, that decreases or eliminates the creation of dead and hot 
spots when broadcasting in large open or enclosed areas. 
Another object of the present invention is to provide a loudspeaker that 
utilizes the rear sound waves created by its speaker drivers. 
An additional object of the present invention is to provide a loudspeaker 
having a rigid and durable, yet light-weight cabinet which can be hung 
from above and support weight hung below. 
These and other objects of the present invention are achieved by a 
loudspeaker including a generally spherical cabinet and at least one 
speaker driver contained in the cabinet and dividing the cabinet into a 
major sound chamber and a minor sound chamber. The cabinet has at least 
two sound propagation ports communicating with the major sound chamber and 
at least two sound propagation ports communicating with the minor sound 
chamber. The spherical cabinet of the loudspeaker provides an 
omni-directional radiation pattern, while the two sound chambers allow the 
loudspeaker to utilize both the front and the rear sound waves of the at 
least one speaker driver. 
According to one aspect of the present invention, the at least one speaker 
driver comprises two speaker drivers facing each other and connected out 
of electronic phase so as to operate as a single push-pull unit. The 
loudspeaker, therefore, is able to further utilize the rear sound waves 
created by its speaker drivers. One of the speaker drivers is 
substantially contained in the minor sound chamber and the other of the 
speaker drivers is substantially contained in the major sound chamber. 
According to another aspect of the present invention, the loudspeaker 
further includes at least one support assembly extending through the 
cabinet and linking opposing hanging points on the outside of the cabinet. 
The loudspeaker, accordingly, can be hung from above and support weight 
hung below without requiring that the cabinet itself bear the weight. 
The invention and its particular features and advantages will become more 
apparent from the following detailed description considered with reference 
to the accompanying drawings.

DETAILED DESCRIPTION OF THE INVENTION 
Referring to FIGS. 1-6, the present invention provides an omni-directional 
sub-bass loudspeaker 10. The loudspeaker 10 includes a generally spherical 
cabinet 20 and at least one speaker driver contained in the cabinet and 
dividing the cabinet into a major sound chamber 40 and a minor sound 
chamber 42 (although the loudspeaker is shown with two speaker drivers 
30,32, the loudspeaker could be provided with only one speaker 
driver--either 30 or 32). As their names imply, the major sound chamber 40 
is of greater volume than the minor sound chamber 42. The cabinet 20 has 
at least two sound propagation ports 22 communicating with the major sound 
chamber 40 and at least two sound propagation ports 24 communicating with 
the minor sound chamber 42. The spherical cabinet 20 of the loudspeaker 10 
provides an omni-directional frequency response, while the two sound 
chambers 40, 42 allow the loudspeaker to utilize both the front and rear 
sound waves of the at least one speaker driver. 
The loudspeaker 10, however, preferably includes a first speaker driver 30 
and a second speaker driver 32, with the two speaker drivers mounted 
facing each other and connected out of electronic phase so as to operate 
as a single push-pull unit. This increases the loudspeaker sensitivity and 
power handling, and permits reducing the driving impedance. Because the 
speaker drivers 30,32 are configured as a push-pull unit, the loudspeaker 
10 is able to further utilize the rear sound waves created by the speaker 
drivers. The first speaker driver 30 is substantially contained in the 
major sound chamber 40, while the second speaker driver 32 is 
substantially contained in the minor sound chamber 42. 
The loudspeaker 10 also preferably includes at least one support assembly 
50 extending through the cabinet 20 and linking opposing hanging points on 
the outside of the cabinet. The loudspeaker 10, accordingly, can be hung 
from above and support weight hung below without requiring that the 
cabinet 20 itself bear the weight. 
In general, for best sound reproduction it has been found that a ratio of 
the volume of the major sound chamber 40 to the volume of the minor sound 
chamber 42 should be between about 2:1 to about 4:1, and preferably 
between about 2.6:1 to about 3.5:1. 
In addition, the cabinet 20 should have at least three sound propagation 
ports 22 communicating with the major sound chamber 40 and at least three 
sound propagation ports 24 communicating with the minor sound chamber 42, 
with the three sound propagation ports of each sound chamber equally 
spaced apart to provide output every one hundred and twenty degrees. Also, 
the number of sound propagation ports 24 communicating with the minor 
sound chamber 42 should be from about 1.5 to about 3 times the number of 
sound propagation ports 22 communicating with the major sound chamber 40. 
The sound propagation ports 22 communicating with the major sound chamber 
40 should each have a diameter of between about 15.5% and about 22.5% of 
the diameter of the cabinet 20, and the sound propagation ports 24 
communicating with the minor sound chamber 42 should each have a diameter 
of between about 8% and about 15% of the diameter of the cabinet. 
Furthermore, the loudspeaker 10 preferably includes major tuned port tubes 
26 positioned in the sound propagation ports 22 communicating with the 
major sound chamber 40, and minor tuned port tubes 28 positioned in the 
sound propagation ports communicating with the minor sound chamber 42. It 
has been found that the major tuned port tubes 26 should extend into the 
major sound chamber 40 a distance equal to between about 80% and about 
120% of the diameter of the ports 22. In addition, the minor tuned port 
tubes 28 should extend into the minor sound chamber 42 a distance equal to 
between about 80% and about 70% of the diameter of the ports 24. 
Front sound waves created by the first speaker driver 30 and rear sound 
waves created by the second speaker driver 32 are propagated through the 
major tuned port tubes 26. While front sound waves created by the second 
speaker driver 32 and rear sound waves created by the first speaker driver 
30 are propagated through the minor tuned port tubes 28. In addition to 
utilizing both the front and the rear sound waves of the speaker drivers 
30,32, the spherical cabinet 20 also acts as a natural acoustic filter for 
the speaker drivers and provides an omni-directional radiation pattern 
that decreases or eliminates the creation of dead and hot spots when the 
loudspeaker 10 is used in large open or enclosed areas. 
Advantageously, in the most preferred embodiment, the spherical cabinet 20 
is defined by three segments, a top segment 80, a middle segment 90 and a 
bottom segment 100. The top and the middle segments 80,90 cooperate with 
an annular plate 92 to form the major sound chamber 40, while the bottom 
segment 100 cooperates with the annular plate to form the minor sound 
chamber 42. Each segment is made of a suitably rigid and lightweight 
material, such as fiberglass polyester or high impact plastic for example. 
The top segment 80 is in the shape of about half a hollow sphere, and has 
hollow fins 70 extending therefrom, with each fin having an upwardly 
facing mounting hole 104. The top segment 80 also includes the circular 
sound propagation ports 22, and fixed in each port is one of the major 
tuned port tubes 26. Preferably, the top segment 80 has three sound 
propagation ports 22, equally spaced apart, and three major tuned port 
tubes 26. 
The middle segment 90 includes a sidewall 94 and the annular plate 92 
extending inwardly from the bottom of the sidewall as a unitary piece. The 
annular plate 92, however, could alternatively be provided as a separate 
piece. The speaker drivers 30,32 are mounted on a bottom surface of the 
annular plate 92 using screws 66, for example, with the second driver 32 
extending into the major sound chamber 40 and the first driver 30 
extending into the minor sound chamber 42. The top segment 80 is sealingly 
joined to the top of the sidewall 94 of the middle segment 90 with 
fiberglass 111, for example, and a rubber gasket ring 110 is secured 
therebetween to provide a smooth exterior joinder. 
The bottom segment 100 of the cabinet 20 is in the shape of less than half 
a hollow sphere, such that the shape of the three segments 80,90,100, when 
combined, approximates a sphere. The bottom segment 100 has hollow fins 
102 extending therefrom, with each fin having a downwardly facing mounting 
hole 104. The bottom segment 100 also includes the circular sound 
propagation ports 24, and fixed in each port is one of the minor tuned 
port tubes 28. Preferably, the bottom segment 100 has six sound 
propagation ports 24, equally spaced apart, and six minor tuned port tubes 
28. The bottom segment 100 additionally has an inwardly extending, 
annular, stepped flange 106 formed as a unitary piece with the bottom 
segment, and an annular gasket 108 is seated thereon. The stepped flange 
106 could alternatively be provided as a separate piece. The annular plate 
92 of the middle segment 90 sits on the stepped flange 106 of the bottom 
segment 100 with the annular gasket 108 therebetween. The loudspeaker 10 
preferably includes a layer of fiberglass insulation 122 covering the 
interior of the bottom segment 100. 
The three segments 80,90,100 of the spherical cabinet 20 are held together 
with the support assemblies 50, which extend from the hollow fins 72 of 
the top segment 80, through the annular plate 92 of the middle segment 90, 
and to the hollow fins 102 of the bottom segment 100. Preferably, the top 
segment 80 has three hollow fins 72, equally spaced apart, the bottom 
segment 100 has three hollow fins 72, equally spaced apart, and the 
loudspeaker 10 has three support assemblies 50 extending between the three 
hollow fins of the top segment and the three hollow fins of the bottom 
segment. Each support assembly 50 links opposing upper and lower hanging 
points 52;54 on the outside of the cabinet 20, which are preferably in the 
form of threaded eyebolts as shown. In addition to holding the cabinet 20 
together, the support assemblies 50 allow the loudspeaker 10 to be hung 
from above and support a weight from below independently of the cabinet. 
The support assemblies 50, therefore, allow the cabinet 20 to be designed 
with less strength, reducing the overall weight, complexity and cost of 
the loudspeaker 10. In fact, it has been found that a loudspeaker 10 
according to the present invention can be over 50% lighter than comparably 
sized existing loudspeakers. It should be noted, however, that in addition 
to being light-weight, the spherical cabinet 20 is also rigid and durable. 
As shown in FIG. 1, the loudspeaker 10 is intended to be hung from a 
ceiling with, for example, cables 112 connected to the upper hanging 
points 52. In addition, a hemispherically wide-radiating-angle loudspeaker 
120 (shown and disclosed in U.S. Pat. No. 5,268,538 to Queen) can be hung 
from below the sub-bass loudspeaker 10 with, for example, cables 66 
connected to the lower hanging points 60. 
As shown best in FIGS. 4 and 6, each support assembly 50 includes two 
threaded tubes 56,58, a threaded rod 60, four metal washers 62, and four 
rubber washers 64. One of the threaded tubes 56 extends between one of the 
fins 72 of the top segment 82 to the annular plate 92 of the middle 
segment 90, and the other threaded tube 58 extends from the annular plate 
to one of the fins 102 of the bottom segment 100. The threaded tubes 56,58 
are secured together with the threaded rods 60, which extend through holes 
68 in the annular plate 92. The upper hanging point 52 extends through the 
mounting hole 104 of the fin 102 of the top segment 80 and is threadedly 
secured in the threaded tube 56, while the lower hanging point 54 extends 
through the mounting hole 104 of the fin 102 of the bottom segment 100 and 
is threadedly secured in the threaded tube 58. The hanging points 52,54 
and the threaded tubes 56,58 are separated from the cabinet 20 by the 
metal and rubber washers 62,64, with the rubber washers abutting and 
protecting the cabinet. 
The loudspeaker 10 also includes an input plug 34, for connection to an 
input signal wire 35. Although its precise positioning is not critical, 
input plug 34 can be easily positioned in one of the fins 72 of the top 
segment 80 and connected to the speaker drivers 30,32 with a wire 36. An 
output plug 37, for connection to a signal wire 38 of the hemispherically 
wide-radiating-angle loudspeaker 120, is can be positioned in one of the 
fins 102 of the bottom segment 100 and connected to the speaker drivers 
30,32 with a wire 39 (although not specifically shown or discussed, the 
wiring of the speaker drivers is generally known in the art). 
In summary, the present invention furnishes a loudspeaker 10 that provides 
an omni-directional radiation pattern, especially with low frequencies, 
that decreases or eliminates the creation of dead and hot spots when 
broadcasting in large open or enclosed areas. The present invention also 
provides a loudspeaker 10 that utilizes the rear sound waves created by 
its speaker drivers 30,32, and a loudspeaker that has a rigid, durable yet 
light-weight cabinet 20 which can be hung from above and support weight 
hung below. 
Although the invention has been described with reference to a particular 
arrangement of parts, features and the like, these are not intended to 
exhaust all possible arrangements or features, and indeed many other 
modifications and variations will be ascertainable to those of skill in 
the art.