Loudspeaker system
United States Patent [19]
[11]
Patent Number:
4,524,846
Whitby
[45]
Date of Patent:
Jun. 25, 1985
[ 54 ]
[76]
LOUDSPEAKE R S Y STEM
Inventor: Ronney J. Whitby, 8067 Center
FOREIGN PATENT DOCUMENTS
Pkwy.’ Sacramento’ Calif‘ 95823
796407 10/1935
,
France .............................. 1. 181/152
Primary Examiner——L1 T. Hix
[21] APPI' No" “L495
Assistant Examiner—-Brian W. Brown
[22]
Attorney, Agent, or Firm—-Leonard Bloom
Filed:
Mar. 2, 1983
[51]
Int. Cl.3 ............................................. .. HUSK 5/00
[52]
US. Cl. .................................. 7. 181/152; 181/147;
Isl/159; Isl/156
[58]
Field of Search ............. .. 181/144, 145, 152, 159,
131/146’ 132’ 133, 187, 192, 160, 194’ DIG 1’
[57]
ABSTRACT
_
_
_
A loudspeaker system has an elliptical stepped mid
range horn above and coplanar with *1 ?ared mid-bass
horn having disposed therein a pair of tweeters on side
156
walls thereof and a woofer in a backwall thereof. The
back of the woofer communicates with a folded low
frequency bass horn such that low frequency response is
loaded from the rear of the diaphram for the woofer
2,808,121 10/1957 Goettner ............................. ._ 181/31
driver’ thereby eliminating the necessity for further
2,975,852 1/1953 Chane
131/155
ampli?cation and drivers to obtain ?delity in low fre
181/31 B
quency response. The low frequency bass section de
56
R f
C, d
e erences lte
US. PATENT DOCUMENTS
[ 1
3,729,061
4/1973 Tamura .
1(9);
,
,
avails ----- -'
er
ino
. . . . .
~ 131/11739I/Ci-é
. . . . . ..
?nes a convoluted path for the sound which comes from
~
4,138,594 2/1979 K?psch
4,139,734
2/1979
Fincham
179/1 E
4,325,454
4/1982
Humphrey ..... ..
181/145
4391346
7/ 1983 Murakami et a1. ................ .. 181/147
181/145
-
-
the 1Ilt.CI‘1§)LStI'L1C;Ufe1 of affolded horn tlllus creating an
acousnca
005‘ or "W “quency sou“ -
15 Claims, 4 Drawing Figures
U.S. Patent
Jun. 25, 1985
4,524,846
1
4,524,846
LOUDSPEAKER SYSTEM
BACKGROUND OF THE INVENTION
The instant application relates generally to the ?eld
2
a single frequency thus producing an interference tone,
due to a harmonic response by the horn to the single
frequency. Furthermore. there is often a problem in
of loudspeaker system, and more speci?cally to a sys
high ef?ciency sound dispersion with the molded con
tiguous surfaces associated with the conventional horn
driven by a mid-range driver. These problems are
tem of horns that are more ef?cient and matched one to
solved in the instant application by the provision of the
another clue to the placement ofthe components and the
elliptically mouthed, stepped mid-range speaker that
con?guration of the horns themselves.
The great proliferation of electronic recording and
reproduction equipment in the past two decades has led
to a variety of theories concerning sound reproduction
and an attendant plethora of speaker con?gurations to
provides an acoustic choke to the bell resonance effect
reflect theories concerning greater ?delity. Today,
speaker enclosures are available in all shapes and sizes,
each claiming advantages over the other. Since accu
rate sound reproduction must cover a range of frequen
cies from a high frequency to a low frequency, a good
loudspeaker system is usually constructed from a num
ber of components ranging from tweeters to mid-range
to mid-bass to bass components. It is often the case that
a speaker system will sound particularly bright or lively
through certain frequency ranges but sound flat or dead
in other frequency ranges. Therefore, a speaker system
must have its components tuned or matched to one
another in order to effect smooth transitions between
components as frequency ranges change.
More speci?cally, a loudspeaker system, especially
those used in the commercial presentation oflive music,
often emphasizes the heavy lower bass frequencies at
the expense of the response of the entire system. This
requires heavy, lower ef?ciency speaker cones which
slow down the response dynamics of the speaker and
and increases radial dispersion of the sound by provid
ing a series of elliptical steps that each become a horn
mouth for a certain frequency associated therewith,
thereby eliminating bell resonance and increasing mid
range horn ef?ciency and dispersion.
A ?nal problem encountered in prior art devices and
solved by the device according to the instant applica
tion is the matching of the high frequency response to
the rest of the components so that the high frequencies
are not overpowered and muted by the over ampli?ca
tion of the lower frequency ranges. This problem is
solved by placing the tweeters inside the mid-bass horn
in a precise relationship with the mid-bass driver
thereby taking advantage of the sound dispersions sur
faces contained therein and providing a means to easily
match the power afforded to the various frequency
ranges.
The prior art of which applicant is aware that would
appear to be germane to the patent process is as follows
US. Pat, Nos: 2,808,121, Goettner 2,975,852, Chave
3,729,061,
Tamura 4,119,799,
Merlino 4,138,594,
Klipsch 4,325,454 Humphrey.
frequency speakers in the system. Many designs have
Of the prior art citations, the patent to Chave is of
interest since he teaches the use of loading a folded bass
horn from the diaphram of a driver which also loads an
acoustic enclosure from the front. The device accord
been tried in an attempt to overcome this problem,
ing to the instant application is distinguished in that it
however, the end result is always a compromise and the
provides a series of compression chambers and com
require much more ampli?cation. Therefore, this mode
of presentation does not balance well with the higher
prior art problems remain.
pression baf?es which facilitate the excitement of the
A further problem involved in the bass response of 40 column air contained within the bass horn chamber.
public address and loudspeaker systems is the acoustical
Furthermore, the patent to Chave exhibits a meander
impedance seen by the driven diaphram in a front
ing convoluted path for the sound to travel through the
loaded horn with a rear enclosure which creates a com
folded horn section of the bass speaker enclosures
pression chamber that effects the motion of the dia
which results in acoustical muting of the sound rather
phram in certain modes of response.
45 than an acoustical boost which is the effect ofthe device
These two prior art problems are addressed and
solved in the device according to the instant application
by providing a woofer with a front loaded horn and a
rear loaded folded horn which is responsive to lower
frequencies so that the diaphram motion is in linear
phase alignment, which can be de?ned as a balance
between the positive impedance encountered by the
front loading and the negative impedance encountered
according to the instant application.
The patents to Klipsch and Tamura are of interest
since they both teach the use of redirecting the lower
frequencies through a cabinet enclosure to invert the
phase and enhance the resultant sound. However, nei
ther of the aformentioned citations provide baffle plates
to de?ne acoustic compression chambers to boost lower
frequency resonance. Furthermore, the interior curved
lower limits of the front loaded horn are equal to the 55 surfaces of the folded base horn enclosure in the instant
by the rear loading of the diaphram. Furthermore, the
upper limits of the low bass horn which accesses the
rear side of the diaphram. Thus. one acoustic driver
drives both the mid-bass horn and the folded low bass
horn. thereby eliminating the problems encountered in
prior art devices such as non-linearity and non-compati
bility. Furthermore. the close coupling of the mid-bass
horn mouths enhance the overall function of the lower
frequency range of components of the speaker system.
The reproduction of mid-range frequency sound also
presents a series of unique problems. Most notable is the
bell resonance effect so common to traditional mid
range speaker horns, such as those often seen in public
address systems. Often the horn itself will resonate with
invention provide advantages when trying to excite the
column of air contained thereon.
Further distinguishing characteristics of the instant
invention will become apparent when considering the
detailed speci?cations to follow
OBJECTS AND SUMMARY OF THE
INVENTION
A primary object of the present invention is to pro
vide a loudspeaker system in which the components are
more readily tuned one to the other, because of the
con?guration provided by the speaker enclosures them‘
selves.
3
4,524,846
It is a further object of the present invention to pro
4
?ared horn 12 which has a series of successive steps 13
creating a series of successively greater area acoustical
mouths as is also shown in FIG. 4. Each step 13 is
formed at 90° to the previous step and is likewise
formed at 90° to a center line of the horn 12 itself. The
elliptical steps 13 are disposed such that the longer axis
is horizontal and the shorter axis is vertical. The steps
vide a loudspeaker system which provides a high fidel
ity sound for live music and recorded music.
It is a still further object of the present invention to
provide a loudspeaker system which is particularly well
suited for the reproduction or transmission of the
human voice, thereby overcoming the current problem
with the poor quality of public address systems pres
on a horizontal plane follow an exponential curve as
ently being used.
they radiate forwardly for the final ?are of the horn 10.
Similarly. the steps on a vertical plane radiate forwardly
It is another object of the present invention to pro
vide a loudspeaker system which can enhance bass reso
on a hypex curve with each step flaring out to the ?nal
nance response by taking advantage of the rear face of
the woofer diaphram to drive the lower bass horn
which boosts lower frequency response without the
requirement of additional ampli?cation or larger,
step ofthe mouth of horn 12. These two ?ares in combi
nation enhance the horizontal dispersion of the sound
eminating from the horn 12. The problem of bell reso
nance associated with single frequency feedback re
heavier diaphrams.
entering the speaker is alleviated by the steps 13 which
It is a still further object of the present invention to
provide a loudspeaker system in which the tweeters
take advantage of the mid-bass horn enclosure to pro
create an acoustical choke. Each successive step 13
forms an acoustical mouth, each successive mouth re
sponding to a different mid-range frequency re?ected
vide recovery of high frequency defraction which ordi
therefrom. The horn 10 is driven by a commercially
available and compatible driver 14 which is fitted to the
throat portion of the horn 12, as shown in FIG. 4.
provide a loudspeaker system in which the mid-range
The mid-bass horn generally referred to by reference
horn is a stepped elliptical transformer to provide a
20, has an open front mouth 15, FIG. 3, two sidewalls l6
wider horizontal sound dispersion pattern and simulta 25 and 17 top wall 18 and a bottom wall 19, all of the walls
neously provide an acoustic choke to prevent the occu
?aring inwardly and tapering to a rear wall 21 which
narily causes the tweeters to lose coherence.
It is a still further object of the present invention to
has opening 22, the horn throat, adapted to overly and
receive a commercially available and compatible
woofer 23 secured in the opening 22 and directed out
wardly toward the mouth 15 of the mid-bass horn 20.
The opening 22 is slightly smaller than the diameter of
rence of bell resonance, or the harmonic ringing of
horns with smooth shapes.
It is still another object of the present invention to
provide a loudspeaker system in which the cutoff fre
quency of the front loading mid-base horn is compatible
with the upper frequency limit of the rear loading horn
to produce a smooth acoustic cross-over due to the
the woofer 23 which creates a controlled impedence
equal to the impedence encountered in rear loading,
utilization of both sides of the woofer diaphram.
thus positive and negative impedence are equalized. As
It is a still another object of the present invention to 35 best shown in FIG. 3, the sidewalls are ?ared outwardly
provide a loudspeaker system in which a single woofer
from the opening 22 in an exponential curve to the
diaphram is used to drive both the mid-bass and bass
outside edge 24 which is substantially 90° from a center
horns.
line axis of the mid-bass horn 20. This ?aring maximizes
It is a still further object of the present invention to
dispersion of the sound eminating from the horn. This
provide a loudspeaker system which ensures that the
can be readily observed in FIG. 3 where the inside
acoustic impedence seen by the woofer diaphram is of
surfaces of the sidewall 16 and 17 are a smooth curve,
the same nature for both front and rear loading.
whereas the exterior portions of the sidewalls 16 and 17
It is still another object of the present invention to
are an approximation of that curve. The sidewalls 16
provide a loudspeaker system that improves efficiency
and 17 have two passages 27 and 28 adapted to receive
and dispersion so that audience coverage is maximized 45 two tweeters 25 and 26, the tweeters being aimed sub
and power input is minimized.
These and other objects will become manifest when
considered in light of the following detailed description
stantially forwardly and positioned to take advantage of
the bene?cial shape of the mid-bass horn 20 itself and to
allow for the easy balancing of the components on a
power-ampli?cation basis. The tweeters 25, 26 are in a
precise relationship with the dome 29 on the woofer 23.
Reference line A FIG. 3, describes a circular are which
passes through the center of the tweeters 25, 26 and the
dome 29 of the woofer 23. Thus the distance R from the
center point C of the reference are A is the same for
taken in conjunction with the accompanying drawings
wherein like reference numerals represent like parts
throughout the several ?gures found therein.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective view of the completely assem
bled speaker system.
each component. This relationship ensures time align
ment of the tweeters, thus the sound eminating from the
tweeters 25, 26 and the woofer 23 reaches the audience
simultaneously and in phase, i.e. time alignment. The
FIG. 2 is a sectional view of that which is shown in
FIG. 1 taken along lines 2~—2.
FIG. 3 is a top sectional view ofthe mid-bass speaker
showing the two tweeters
FIG. 4 is a partial sectional of the elliptical horn
aiming ofthe tweeters 25 and 26 allow for the maximum
dispersion of high frequency waves. As best shown in
FIG. 2, the top and bottom walls 18 and 19 of the mid
bass horn 20 are similarly ?ared except that these both
transformer showing the stepped mouths integral
thereto.
DETAILED DESCRIPTION OF THE
PREFERRED EMBODIMENT
Referring now to FIG. 1, reference numeral 10 is
directed to the mid-range acoustic transformer which
has a front wall 11 with a centrally disposed, elliptically
follow a hypex curve instead of a exponential curve
relationship. Once again, this ?aring aids in sound dis
65
persions.
The low bass horn generally referred to by reference
numeral 30, has an upper section 31 which communi
cates with the rear of the mid-bass horn 20 and is
5
4,524,846
formed to receive the rear of the woofer 23 through an
opening 32 in the front face of the upper section 31 of
the throat of low bass horn 30. The lower section 33
(horn mouth) of the low bass horn 30 is joined to the
upper section (horn throat) by means of a clasp 38, the
two together forming one contiguous folded horn.
Once again. the interior of the lower bass horn section
33 is a curved surface approximating the curve found in
a base tuba. The mouth of the lower bass horn section
assists in creating an acoustical boost for the lower bass
6
same woofer 23. the result being a smooth transition and
an acoustic coupling to the two horns without the ne
cessity of added ampli?cation or a larger and stiffer
type woofer diaphram which results in slow woofer
response and a lack of linear phase clarity among the
various components.
In use and operation the horns 10, 20 and 30 are ac
coustically coupled as shown in FIG. 1 and similarly
directed in a coplanar fashion so that a full range of
O
frequency response is targeted outwardly. Each of the
frequencies. As is shown in FIG. 1 taken in combination
components is tuned to one another and neither mutes
with FIG. 2, the exterior walls of the lower bass horn
the other due to the acoustical choking effect created by
section 33 are approximations of the smooth interior
the elliptical steps 13 of the mid-range horn 10, the
surfaces of the walls defining the lower bass horn sec
placement of the tweeters 26 and 27 within the mid-bass
tion 33. The top and bottom walls 38 and 39 in FIG. 2 5 horn 20, and the front and rear loading of the woofer 23
have three exterior facets which help to de?ne the inte
thereby eliminating the need for additional, slow re
rior curve of said walls. Similarly, the sidewalls 40 and
sponding components which often dominate the resul
41 have a series of facets which de?ne the smooth inte
tant sound reproduction. The result is a speaker system
rior surfaces created therefrom. The walls and struc
high in ?delity through the entire audible frequency
tures associated with all three acoustic horn 10, 20, and
ranges created by the various, integrated components.
30 are constructed from molded ?berglass or the like,
Having thus described the preferred embodiment of
resulting in the multifaceted exterior surfaces and the
the invention, it should be understood that numerous
smooth acoustically pleasing interior surfaces. It should
structural modi?cations and adaptations may be re
also be noted that the molds forming the horns may also
sorted to without departing from the spirit of the inven
be designed to produce smooth, rounded exterior sur 25 tion.
faces as well as the multifaceted exterior walls shown in
I claim:
the present embodiment.
1. A loudspeaker system comprising, in combination:
The upper section 31 of the low frequency bass horn
a mid-range acoustic transformer including a ?ared,
30 receives the back of the woofer 23 as previously
stepped elliptical horn with a mid-range driver
noted. The woofer diaphram is used to rearwardly load 30
therein;
the entire low frequency bass horn 30, thus a single
a woofer having a diaphragm;
woofer diaphram of the woofer 23 is loaded on both a
a mid-bass acoustic horn mounted below said mid
front side and a rear side, thereby reducing acoustic
range acoustic transformer, said mid-range bass
imedence and increasing the output and balance ‘of low
acoustic horn having said woofer with said dia
frequency sound. The sound path of the folded horn as 35
phragm disposed on a rear wall thereof to provide
shown by the directional arrows, effecting an acoustical
said diaphragm with a positive operational impe
boost is produced to increase low frequency response.
dance encountered by front loading, said mid-bass
A ?rst acoustical horn section 34 is de?ned by a trun
acoustic horn having at least two opposing curved
cated upper wall 42 of the upper section 31 and the
walls;
baffle 36 depending downwardly and inwardly there 40 a low-bass acoustic horn positioned directly beneath
from. The ?rst acoustical horn section 34 communicates
said mid-bass acoustic horn and having a folded
with a second acoustical horn section 35 de?ned by a
horn interior section which communicates with
lower side wall 43 and the upwardly extending baffle
rear of said woofer to provide said diaphragm with
member 37. These acoustical horn section 34 and 35 in
combination create a folded tapered space between the 45
woofer 23 and the lower folded horn section 33 thereby
creating acceleration of the sound waves therethrough
a negative operational impedance encountered by
which more quickly excites the column of air contained
low-bass acoustic horn by said diaphragm of said
woofer; and
in the horn 30. The baffles 36 and 37 also act as a cross
over ?lter by eliminating frequencies above 150 HZ
which will not pass along the path indicated by the
rear loading, a balance being provided between
said positive and negative operational impedances,
a lower frequency response being provided to said
a pair of tweeters disposed on said opposing curved
walls of said mid-bass acoustic horn, which curved
directional arrows FIG. 2. The baffles 36 and 37 are
walls disperse high frequency waves from said
constructed from audio absorbant material which aids
in preventing any wrongly defracted sound waves from
tweeters.
returning and impeding the oscillation of the diaphram
in the woofer 23. the sound travels through the folds
created by the baffle to the greater expanse of the upper
section 31 de?ned by the rear wall 44 and then down
55
2. The loudspeaker system according to claim 1,
wherein said mid-range acoustic transformer comprises
an elliptical stepped horn having a plurality of elliptical
steps, each of said steps being substantially at 90° angles
wardly into the larger cavity created by the lower sec
with respect to each successive step so that a series of
horn mouths are formed, each successive said mouth
tion 33 of the low frequency bass horn 30. This con
yaluted path ensures that the sound eminating from the
two speaker horns 20 and 30 will be in phase when
being greater in area and responding to and radiating
successively greater pass band frequency wave lengths.
whereby sound dispersion is greatly increased and an
projected outwardly from these mouths of the two
horns which are directed coplanarly. Similarly, the
acoustic choke is formed to impede reentry of wave
mid-range horn 10 is aimed in the same direction. The
cal horn.
lower cutoff frequency ofthe mid-bass horn 20 coincide
with the upper frequency response of the low bass horn
30 so that in conjunction they both operate from the
3. The loudspeaker system according to claim 2,
wherein said mid-range transformer and said elliptical
steps associated therewith form said gradually increas
lengths which might be diffracted back into said ellipti
7
4,524,846
ing mouths, said mouths being horizontally oriented and
following an exponentially increasing horizontal ?are
8
depending from a wall of said upper section and
de?ning dead air space between the rear of said
woofer and said baffle means, whereby low fre
quency sound waves from said woofer excite the
dead air space and are repercussed and boosted by
said ?rst acoustical portion and directed into said
second acoustical portion; and
a lower section of said folded low-bass horn joined to
and communicating with said upper section and
and a vertical flare, all of said steps being at a 90° angle
from the axis of a center line of the horns.
4. The loudspeaker system according to claim 1,
wherein said mid-range transformer including said
stepped horn is mounted directly above said mid-bass
acoustic horn and is aimed in the same direction.
5. The loudspeaker system according to claim 4,
wherein said mid-bass acoustic horn has an open front 0
of substantially larger area than said rear wall which has
an opening therein adapted to receive said woofer and
further having top and bottom walls connecting said
gradually expanding downwardly and forwardly
therefrom, terminating in an acoustic mouth situ
ated directly beneath and coplanar with said open
front in said mid-bass acoustic horn.
10. The loudspeaker system according to claim 9,
rear wall two said open front, said top and bottom walls
following a flare curve forwardly, and wherein said at 5 wherein said baffle means comprises ?rst baffle means
least two opposing curved walls are sidewalls connect»
depending from a top wall of said upper section and
ing said front opening to said rear' wall, said sidewalls
directed downwardly and slightly forwardly forming a
following an exponential flare curve forwardly.
6. The loudspeaker system according to claim 5,
wherein said mid-bass acoustic horn has in center of
rear portions of each of said sidewalls a portal adapted
tapered, necked down dead air space between the rear
of said woofer and said ?rst baffle means, whereby low
frequency sound waves from said woofer excite the
dead air space and are repercussed and boosted by said
to receive one of said tweeters, each of said tweeters
?rst acoustical portion and directed downwardly into
said second acoustical portion.
11. The loudspeaker system according to claim 10.
being positioned in respective said portals and being
aimed substantially forwardly and inwardly, said tweet
ers and said Woofer being in arcuate relationship equi
wherein said second acoustical portion is de?ned by a
distant from a center point within said mid-bass acoustic
downwardly and rearwardly directed sidewall of said
horn thereby establishing a linear time alignment of
different frequencies of sound coming from said tweet
upper section and a second baffle means extending up
perwardly and rearwardly from said sidewall of said
ers and said woofer.
upper section, whereby sound waves directed down
wardly from said ?rst acoustical portion are boosted
and repercussed upwardly from said second acoustical
portion thereafter reflecting off of a top wall of said
7. The loudspeaker system according to claim 6,
wherein said woofer and said opening in said rear wall
of said mid-bass acoustic horn are dimentioned to pro
vide the balanced positive and negative operational
upper section, being then directed downwardly into
impedences encountered by said diaphram of said
woofer.
35 said lower section by a rear wall of said upper section
and said second baffle means.
8. The loudspeaker system according to claim 7,
12. The loudspeaker system according to claim 11,
wherein said sidewalls and said top and bottom walls
wherein said lower section has smooth curved inner
within said mid-bass acoustic horn and walls of said bass
surfaces contiguous with inner surfaces of said upper
acoustic horn have substantially smooth interior sur
faces.
40 section to direct sound waves toward said acoustic
mouth of said lower section.
9. A loudspeaker system in which a bass transformer
13. The loudspeaker system according to claim 12,
approximates a folded low-bass horn, the system com
prising, in combination:
wherein said first and said second baffle means are
formed from panels of an acoustically absorbant mate
a woofer having a diaphragm;
a mid-bass transformer including a mid bass horn 45 rial and completely transverse said upper section and
?lter out frequences above about 150 HZ.
having an open front and providing said diaphragm
14. The loudspeaker system according to claim 13,
with a positive operational impedance encountered
by front loading;
wherein said second baffle means has a thickened base
portion with an upwardly and forwardly directed face
an upper section of said folded low-bass horn commu
to reflect sound waves upwardly from said second
acoustic portion towards the rear surface of said ?rst
nicating with rear of said woofer and providing
said diaphragm with a negative operational imped
ence encountered by rear loading, a balance being
baffle means, said ?rst baffle means having a thickened
provided between said positive and negative
impedences, a lower frequency response being
provided to said low-bass horn by said diaphragm
base portion forming a rearwardly and downwardly
directed face to reflect sound waves downwardly
towards said lower section.
of said woofer, said upper section having ?rst and
second acoustical portions through which low
15. The loudspeaker system according to claim 14.
wherein said upper section has truncated upper corners
frequency sound waves generated by rear of said
diaphragm in said woofer travel a convoluted path
through said portions and are enhanced, said ?rst
acoustic portion being de?ned by baffle means
forming downwardly directed inner faces to aid in tran
sition of sound waves from said woofer to said acousti
cal mouth of said lower section.
>l<
65
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