Sound collecting and concentrating device for attaching to the back of multiple loudspeakers

A loudspeaker system and a loudspeaker housing system uses a plurality of smaller rated loudspeakers to generate a high-level output. Specifically, the plurality of loudspeakers are housed in a corresponding number of substantially cylindrical sound collecting tubes, one tube for each loudspeaker. Sound waves, which are generated toward the rear of each loudspeaker and which are otherwise attenuated by the insulation material or reflected by baffles and/or walls and ultimately dissipate, instead travel through the tube, the tube forming a sound traveling path. Each tube converge and merge smoothly into a single substantially cylindrical tube. The sound waves traveling through the individual tubes are merged at the converged tube. The outlet of the single converged tube is connected to or is integral with a conventional or specialized sound concentrating horn to direct the captured sound to a desired direction.

BACKGROUND 
The present invention is drawn to a novel loudspeaker system and a 
loudspeaker housing system for capturing and concentrating sound waves 
that are emitted toward the back side of a plurality of loudspeakers. 
In the past, attempts have been made to improve the efficiency of a 
loudspeaker which is capable of accurately reproducing high-fidelity 
sound. Specifically, attempts of improvement have been made in two areas 
of the loudspeaker system: 1) the loudspeaker cone and diaphragm utilizing 
modern materials; and 2) the housing that encases the loudspeaker, to 
reduce unwanted vibration and resonation within the housing. A loudspeaker 
system utilizing or manipulating sound waves directed toward the rear of 
the speaker has been proposed, for example, in U.S. Pat. No. 4,439,644 to 
Bruney, III, U.S. Pat. No. 4,524,846 to Whitby, U.S. Pat. No. 4,655,315 to 
Saville, U.S. Pat. No. 4,807,293 to Weckler, and U.S. Pat. No. 4,930,596 
to Saiki et al. 
In U.S. Pat. No. 4,439,644 to Bruney, III (Bruney), a loudspeaker system 
utilizes a plurality of vinyl sheets having different thicknesses to seal 
the rear of a speaker housing, to relieve pressure behind the loudspeaker 
driver, and to attenuate sound waves emitted toward the rear of the 
speaker. While this type of system minimizes the housing vibration and 
generation of the spring-like compression effect or the resonant booming 
effect often associated with an acoustic suspension enclosure, the speaker 
is not as efficient as a ported speaker system in general. Unlike the 
prior inventions, the present invention captures and concentrates sound 
waves which are emitted toward the rear of at least two loudspeaker and 
directs the sound waves to a singular sound concentrating horn and the 
like. 
In U.S. Pat. No. 4,524,846 to Whitby and U.S. Pat. No. 4,807,293 to 
Weckler, a loudspeaker system directs sound waves radiated rearwardly into 
the chamber(s) in the housing through a convoluted path. This type is 
known to provide a fairly reputable performance. However, due to sound 
waves colliding against baffles stationed in the housing, resonance in the 
baffle and the housing cannot be avoided when driving at high volume 
levels, coloring or distorting its true sound. 
Additionally, in order to produce a high level output the loudspeaker 
diaphragm must be large and the thrust distance, i.e., the forward 
traveling distance, must be relatively long. This structural arrangement 
for producing a high level output requires a special design and expensive 
material. Furthermore, because the diaphragm must be large and strong to 
sustain the high level output, the end result is that the diaphragm will 
have to possess a large inertia (mass), which reduces diaphragm 
sensitivity and undesirably increases the response time, thus reducing the 
high fidelity capability. 
In U.S. Pat. No. 4,655,315 to Saville and U.S. Pat. No. 4,930,596 to Saiki 
et al., a loudspeaker is housed in a specially configured sound collecting 
tube to modify the frequency response. The efficiency of the speaker, 
however, in such an arrangement is reduced because the sound travels 
through restricted openings, which may react much like the baffles in the 
housing. Furthermore, because of the frequency response modification, 
colored or distorted sound is likely to occur, whereas in the present 
invention, a freely aspirated sound collecting tubes do not color the 
sound and thus the sound generated from the loudspeaker is heard directly 
without being colored or distorted. 
In contrast with the prior speaker system, in the present invention, a high 
level output is produced by collecting and concentrating sound waves 
generated from a plurality of smaller rated loudspeakers and output to a 
single horn. The production cost can be significantly reduced vis-a-vis a 
single high-level output loudspeaker system, while fully rendering the 
maximum high-fidelity capability of a smaller rated loudspeaker system 
because of their smaller inertia and thrust distance. Moreover, there are 
no baffle or medium which can cause resonation or unwanted sound 
reflections within the speaker housing. Sound waves passing through the 
tubes are freely "breathable". In other words, pressure build-up behind 
the speaker and sound reflections within the confines of the speaker 
housing, which cause undesirable sound distortion, are avoided or at least 
minimized by routing and concentrating sound waves through the sound 
collecting tubes which house the loudspeakers. 
SUMMARY OF THE INVENTION 
This invention is directed to a novel high level outputting loudspeaker 
system which utilizes a plurality of smaller rated loudspeakers. 
Specifically, the plurality of loudspeakers are housed in a corresponding 
number of substantially cylindrical sound collecting tubes, one tube for 
each loudspeaker. Sound waves, that are emitted from the back side of each 
loudspeaker and that are otherwise attenuated by the insulation material 
or reflected by baffles and/or walls and ultimately dissipate, instead 
travel through the tube, the tube forming a sound traveling path. The 
tubes converge and merge smoothly into a single substantially cylindrical 
tube. Sound waves traveling through the individual tubes are merged at the 
converged tube. The outlet of the single converged tube is connected to or 
is integral with a conventional or customized sound concentrating horn to 
direct the captured sound to a desired direction. 
To minimize the acoustic resistance, the area of the speaker frame which 
supports the diaphragm in the back of the loudspeaker should be minimized 
to prevent sound waves emitted toward the rear of the loudspeaker from 
reverberating off the frame. This maximizes the utilization of sound waves 
that are emitted toward the rear of the loudspeaker diaphragm and in 
return maximizes the efficiency and the high-fidelity capability of the 
loudspeaker system. 
Also, in one embodiment of the present invention, to minimize the acoustic 
resistance in the sound collecting tube, the cross-sectional area of each 
sound collecting tube at the inlet is preferably equal to that of the 
diaphragm. The cross-sectional area of the sound collecting tube at the 
inlet is also preferably slightly greater than that at the outlet, 
although any dimension can be used so long as the tube does not restrict 
or interfere with the sound output. Furthermore, since the permanent 
magnet and the moving coil of the loudspeaker occupies the central area at 
the inlet, the tube must wide enough at the inlet to permit sound waves to 
travel through the tube with a minimum acoustic resistance. The above 
preferred specified dimension permits sound waves to travel through the 
tube with a minimum acoustic resistance. 
In another embodiment, the inlet end of each of the sound collecting tubes 
is preferably substantially equal to at least one of the cutouts or the 
cutout in the back of the loudspeaker so that the inlet can shroud over 
the cutout with minimal sound output interference. The cross-sectional 
area of the inlet is preferably smaller than that at the outlet of the 
sound collecting tube in this embodiment. 
All of the cylindrical sound collecting tubes that houses the loudspeakers 
smoothly join to a single cylindrical tube. At this junction, the cross 
sectional area does not have to be equal to the sum of the individual 
cylindrical tube areas. As long as the sound path from the individual 
collecting tubes to the converged cylindrical tube is smooth as to provide 
a minimum acoustic resistance, the area of the joined cylinder can be made 
close to or slightly greater than the outlet cross-sectional area of the 
individual sound collecting tubes to minimize the overall dimension of the 
present system. 
The outlet of the converged sound collecting tube is connected to or is 
integral with a sound horn which can be in the shape of the horn of the 
brass instruments or sound amplifying horns and the like which collect and 
concentrate sound waves passing therethrough. In essence, the horn 
prevents the sound waves from dispersing radially, and instead 
concentrates sound waves in a specific direction. Moreover, the individual 
loudspeakers can be directed to any desired direction. In other words, the 
loudspeakers can be pointed to different directions relative to each other 
and to the direction of the horn, for example, by using sound collecting 
tubes having different bends and curves. 
Accordingly, one object of the invention is to provide a high level 
outputting loudspeaker system capable of efficiently and accurately 
reproducing high fidelity sound by providing a plurality of smaller rated 
loudspeakers in a corresponding number of sound collecting tubes to 
collect and concentrate sound waves that are emitted toward the rear of 
each loudspeaker. 
Another object of the invention is to provide a loudspeaker system capable 
of concentrating and outputting the combined output to a single horn. 
Another object of the invention is to provide a loudspeaker system having a 
plurality of loudspeakers, in which the loudspeakers can be pointed to 
different directions relative to each other and to the direction of the 
horn by using sound collecting tubes having different bends and curves. 
The use of a plurality of smaller rated loudspeakers with a single sound 
concentrating or focusing horn provides distinctive advantages in lowered 
production cost and increased efficiency while maintaining a high-fidelity 
capability of a smaller rated loudspeaker as compared to a conventional 
high-level outputting loudspeaker, whether it utilizes a single sound 
concentrating horn or not. 
The foregoing invention and features and advantages of the present 
invention will be better understood and appreciated from the following 
description.

DETAILED DESCRIPTION OF THE DRAWINGS 
The present invention, as shown in the drawings, shows five different 
embodiments of the loudspeaker housing. Same reference numerals have been 
designated for same or similar elements. Furthermore, to facilitate better 
understanding of the present invention and to make the drawings less 
complex, the loudspeakers are not shown as being attached to the housing. 
The following description generically applies to all of the embodiments 
contemplated in the present invention. The features distinct to each 
embodiment, which are readily recognizable from the drawings, are 
separately described below. 
The loudspeaker housing 10-50 of the present invention has been 
contemplated for use with a plurality of loudspeakers of the type having 
at least one sound venting cutout in the frame of the loudspeaker which 
supports the cone and the sound driving means. Each loudspeaker of the 
aforementioned type is housed in or attached to one sound collecting tube 
1, using conventional attaching means. The loudspeaker S, shown in FIGS. 
13 and 14, generally has a circular cross section with a mounting flange 
64 for attaching to a flange F of the inlet end of the sound collecting 
tube by a conventional loudspeaker to housing attaching means, i.e., 
screws, bolts, rivets, etc. (not shown). 
The loudspeaker of type presently contemplated comprises a diaphragm 62, a 
cone shaped frame 61 with a plurality of sound venting trapezoidal 
cut-outs T.sub.C. The loudspeaker illustrated has four symmetrical 
trapezoidal cut-outs in the frame. However, the present invention may be 
used with any number of trapezoidal cut-outs, depending on the shape of 
the inlet end. The flange 64 preferably includes a plurality of openings 
(not shown) to permit conventional fastening means such as screws, bolts, 
or rivets to be positioned therein. The openings are merely optional since 
the speaker can be attached using conventional clips and/or adhesive. The 
speaker is attached to the inlet end of the sound collecting tube by any 
said conventional fastening means. However, adhesive or double sided tape 
may be used in addition to the fastening device to securely and sealingly 
fasten the inlet end to the frame. 
Each sound collecting tube houses a single loudspeaker S so that the front 
S.sub.F of the speaker is exposed to the surrounding where the loudspeaker 
output is generally greatest. The entire back side S.sub.B of the 
loudspeaker is housed in the tube 1. Sound that is emitted from the back 
side of each loudspeaker and which is otherwise attenuated by the 
insulation material or reflected by baffles and/or walls of the 
conventional loudspeaker and ultimately dissipate, instead is captured and 
travels through the tube, the tube forming a sound traveling path. 
The sound collecting tubes smoothly merge and converge to a single 
cylindrical tube 4 before forming into an inlet end portion of the horn 3 
to minimize the acoustic resistance through the path of the sound travel. 
While the present embodiments are shown with the converged tube 4 being 
integral with the horn 3, it is to be noted and recognized that it is well 
within the scope and spirit of the present invention to encompass the 
alternative embodiments where the horn can be removably attached to the 
converged tube 4 so that differently directed or shaped horns can be 
readily attached using a conventional tube to tube attaching means such as 
a clamp, friction fit, threaded fit, etc, as described in the previously 
identified copending application, Ser. No. 07/714,529 (U.S. Pat. No. 
5,206,465) and U.S. Pat. No. 5,025,886. 
The horns can be any conventional type. The horns may be readily 
interchangeable if removably attached to enable the listener to use 
different types of horns depending on the music and the listener's taste 
of sound. Note that different horns can produce different sound timbre 
which changes the tone of the sound. The horn 3 shown in the present 
embodiments directs sound waves in the direction facing the front of the 
loudspeaker. A differently curved horns may be also used to direct sound 
waves to a wall or angled walls for reflecting sound waves in a 
multi-directional fashion. 
Similarly, while the inlet opening ends 2 of the sound collecting tubes, as 
shown in all of the present embodiments, are preferably aligned in the 
same direction as the output direction of the horn, the inlet opening ends 
need not be aligned in the same direction. That is, as shown in the 
drawings, the inlet opening ends 2 of the tubes all face in the same 
direction and in the direction of the output of the horn 3. However, it is 
well within the scope and spirit of the present invention to alter the 
direction of the inlet end by interchangeably changing each sound 
collecting tube with differently curved tubes. By using differently curved 
and bent sound collecting tubes, the inlet opening can face in any desired 
direction so as to create a multi-directional loudspeaker system. 
Moreover, the inlet end portion of the sound collecting tubes can be made 
from a pliable tubes which can be readily bent and maintained thereabout 
in any angle and direction with respect to the output direction of the 
horn. 
FIRST EMBODIMENT 
The first embodiment contemplates a use of four sound collecting tubes, as 
shown in the perspective view of FIG. 1. Tubes 1a,1d and 1b,1c are 
vertically aligned and the tubes 1a,1b and 1c,1d are horizontally aligned, 
as shown in FIG. 2. As previously explained, each collecting tube houses a 
single loudspeaker S with the front side S.sub.F facing the ambient and 
the back side S.sub.B facing the inlet end 2. 
SECOND EMBODIMENT 
The second embodiment also contemplates a use of four sound collecting 
tubes, as shown in the perspective view of FIG. 4. However, in this 
embodiment, as shown, the sound collecting tubes are evenly distributed 
and spaced around the circumference of the horn 3. That is tubes 1a', 1b', 
1c', 1d' are spaced apart at 90.degree. intervals, as better shown in FIG. 
5. As previously explained, each collecting tube houses a single 
loudspeaker S with the front side S.sub.F facing the ambient and the back 
side S.sub.B facing the inlet end 2. 
THIRD EMBODIMENT 
The third embodiment also contemplates a use of four sound collecting 
tubes, as shown in the perspective view of FIG. 7. This embodiment, 
however, has the four tubes arranged closely side by side, as better shown 
in FIG. 8. As previously explained, each collecting tube houses a single 
loudspeaker S with the front side S.sub.F facing the ambient and the back 
side S.sub.B facing the inlet end 2. 
FOURTH EMBODIMENT 
This embodiment is substantially similar to the third embodiment, except 
that three sound collecting tubes, as shown in the perspective view of 
FIG. 9, are contemplated rather than four tubes. As previously explained, 
each collecting tube houses a single loudspeaker S with the front side 
S.sub.F facing the ambient and the back side S.sub.B facing the inlet end 
2. 
FIFTH EMBODIMENT 
This embodiment is substantially similar to the fourth embodiment, except 
that two sound collecting tubes, as shown in the perspective view of FIG. 
11, are contemplated rather than three tubes. As previously explained, 
each collecting tube houses a single loudspeaker S with the front side 
S.sub.F facing the ambient and the back side S.sub.B facing the inlet end 
2. 
SECOND EMBODIMENT OF INLET END 
FIGS. 15-17 illustrate the second embodiment of the inlet end, which is 
also similar to the inlet end shown in FIG. 8-1 of my copending Ser. No. 
07/714,529 (U.S. Pat. No. 5,206,465). Instead of the circular, free, 
unobstructed opening shown in the inlet end of the first embodiment, one 
or more or all of the inlet end may be substituted with the inlet end of 
the second embodiment. The inlet end of the second embodiment 52 has a 
diameter that is substantially equal to that of a loudspeaker that is to 
be attached thereto. In this embodiment, the inlet end of the sound 
collecting tube has four trapezoidal inlet segments 53a, 53b, 53c, 53d, 
each with a respective rim or flange 57, formed at each inlet end segment. 
Each flange is attached to a conventional flange formed in the 
conventional loudspeaker, the flange being primarily used for purposes of 
mounting to a housing frame or a support. 
The four inlet segments correspond to the trapezoidal cut-outs formed in 
the back of the loudspeaker. That is, the inlet end of this embodiment is 
mounted to a loudspeaker with each inlet end segment sitting 
concentrically over one or more of the trapezoidal cut-outs T.sub.C in the 
loudspeaker frame so that sound emitted from the back of the loudspeaker 
travels through each inlet end segment with a minimum sound interference. 
Sound further travels through the sound collecting tube where the 
collected sound from each inlet end segment is combined, the combined 
collected sound continuing through and out the horn. 
Each of the trapezoidal inlet segments 53a, 53b, 53c, 53d has a trapezoidal 
cross section, bounded by four walls 58. The trapezoidal cross sections of 
the four inlet segments gradually become larger and larger toward the 
outlet end direction until the four trapezoidal sections merge into a 
single circular cross section in the direction of the sound path. 
The inlet end of the sound collecting tube further has four slots 54 which 
separate the trapezoidal inlet segments and which provide space for the 
frame area between two adjacent trapezoidal cutouts of the loudspeaker to 
rest therein when the loudspeaker is mounted to the inlet end. Further, a 
recessed cavity 55 which is formed by the walls 58 of the respective 
segments 53a, 53b, 53c, 53d is provided for the speaker driving means 60 
of the loudspeaker to rest therein. 
It is to be noted that each inlet end segment shrouds over one or more 
trapezoidal cut-outs in the loudspeaker frame. Thus, the four inlet end 
segments may shroud over a loudspeaker frame having, for example, eight 
trapezoidal cut-outs, each inlet end segment shrouding over two 
trapezoidal cut-outs. 
Alternatively, while the third embodiment is shown with four inlet segments 
for use with a loudspeaker frame having, for example, four trapezoidal 
cut-outs, it is to be noted that the present invention contemplates any 
feasible number of inlet end segments corresponding to the number of 
cut-outs formed in the loudspeaker frame. For example, if a loudspeaker 
frame has five trapezoidal cut-outs, a sound collecting tube formed with 
five inlet end segments may be used. This alternative embodiment may also 
be used with a loudspeaker frame having ten trapezoidal cut-outs, in the 
manner just described. 
THIRD EMBODIMENT OF INLET END 
FIGS. 18-20 illustrate the third embodiment of the inlet end, which is 
similar to the inlet end of FIG. 11-1 of my copending Ser. No. 07/714,529 
(U.S. Pat. No. 5,206,465), which may be also used instead of the first 
inlet end embodiment. The inlet end 82 of the third embodiment is formed 
as a single unitary inlet which is designed to attach to at least one 
trapezoidal cut-out segment in the back of the loudspeaker frame via a rim 
or flange 87 formed at the inlet end. The flange is attached to a 
conventional flange formed in the conventional loudspeaker using said 
conventional attaching means. 
The inlet end has a trapezoidal cross section, bounded by four walls 88. 
The trapezoidal cross sections of the four inlet segments gradually become 
larger toward the outlet end direction. The outlet end may be any size or 
shape so long as it does not substantially interfere with sound output. 
The foregoing description has been only illustrative of the principle of my 
invention. It is to be understood that the present invention is not to be 
limited to the exact configuration and construction as illustrated and 
described herein. Accordingly, all expedient modifications may be made 
within the scope and spirit of my invention. For example, the sound 
collecting tube need not be limited to four tubes. The number of tubes can 
depend on the diameter of the loudspeaker or as matter of listeners 
preference, any feasible number of sound collecting tubes being possible. 
Moreover, while the inlet end has been shown with three specific 
embodiments, other shaped inlet end, such as that of FIGS. 9-1 and 10-1 of 
my copending application Ser. No. 07/714,529 (U.S. Pat. No. 5,206,465) may 
be used, the disclosure of which is incorporated herein by reference.