Grille for loudspeaker cabinet

For use with a cabinet containing at least one loudspeaker, a grille is provided which is comprised of elongated frame members connected by corner brackets. A rigid superstructure, comprising corner ridge members and one or more central ridge members joined by ridge joint members, is attached to the frame at the corner brackets, and a covering material is disposed over the superstructure and frame. Any size grille can be constructed using the same corner brackets and ridge joint members.

BACKGROUND OF THE INVENTION 
This invention relates to grilles for cabinets containing one or more 
loudspeakers, and more particularly, to grilles for such cabinets intended 
for use in consumer sound systems. 
Most loudspeaker cabinets are arranged to project sound from a front-facing 
generally planar surface and require a grille to cover and protect the 
loudspeakers, yet the grille must not present a significant barrier to 
sound emanating from the cabinet. Further, it is often desirable to form 
the outer surface of the grille in a non-planar fashion to enhance the 
aesthetic appearance of the combined cabinet and grille. 
Loudspeaker cabinet grilles available heretofore typically have included a 
cloth material or fabric stretched over a planar frame which conforms to 
the shape of the front face of the cabinet and is often rectangular. This 
arrangement causes the loudspeakers within the cabinet to be vunerable to 
damage from articles of furniture, etc. which may inadvertently come in 
contact with the grille. Non-planar loudspeaker cabinet grilles which have 
been available heretofore have included a foam material secured to the 
frame, and the foam material is carved or cut to form the non-planar 
surface. 
Although many loudspeaker cabinets are rectangular, the size of the 
rectangle varies widely according to the size and number of loudspeakers 
in the cabinet. Producing the numerous different sized parts required to 
make grilles for all of the various sizes of loudspeaker cabinets is an 
expensive undertaking, and this problem is compounded when the 
construction of the grille is complicated by forming a non-planar outer 
surface. 
Accordingly, there has existed a need for a grille for loudspeaker cabinets 
which is attractive, yet provides effective protection for the 
loudspeakers, and is capable of being fabricated conveniently and 
economically in a multiplicity of sizes. The present invention satisfies 
that need. 
SUMMARY OF THE INVENTION 
The invention provides a non-planar grille construction which presents an 
attractive appearance and which substantially reduces the cost of 
producing a multiplicity of sizes of such grilles. Moreover, the grille 
construction of the present invention is sturdy enough to provide adequate 
protection of the loudspeakers, yet does not present a significant barrier 
to sound emanating from the cabinet. 
This is accomplished generally by joining elongated frame members, all of 
which may be of the same tubular construction, into a generally planar 
polygonal frame. The frame members are joined by corner brackets, and a 
superstructure for forming the non-planar surface of the grille is 
constructed of one or more central ridge members and a plurality of corner 
ridge members held together by ridge joint members. The superstructure is 
attached to the frame at the corner brackets, and a covering material is 
then stretched over the superstructure and secured to the frame. 
By using this construction, any size polygonal grille can be produced by 
simply using the required number of corner brackets and ridge joint 
members, and selecting various lengths of frame members and ridge members. 
Other features and advantages of the present invention will become apparent 
from the following detailed description, taken in conjunction with the 
accompanying drawings, which illustrate, by way of example, the principals 
of the invention.

DETAILED DESCRIPTION 
As shown in the exemplary drawings, the present invention is embodied in a 
new and improved grille, indicated generally by reference numeral 10 in 
FIG. 1, for use with a cabinet 12 containing one or more loudspeakers 14 
(FIG. 2). The grille 10 is of the type having a generally planar frame 16 
which conforms with the generally hexagonal shape of the front of the 
cabinet 12, and having a non-planar outer surface 18. 
The grille 10 is mounted on the front of the cabinet 12, and is the surface 
through which sound emanates from the loudspeakers inside the cabinet. The 
grille 10 is readily permeable to sound, and covers that portion of the 
cabinet through which the loudspeakers are most vunerable to damage. 
In accordance with the present invention, the grille 10 is provided with an 
attractive non-planar surface 18, yet provides effective protection for 
the loudspeakers in the cabinet 12. Further, the grille 10 is capable of 
being conveniently and economically fabricated in a multiplicity of sizes. 
Toward the foregoing ends, the frame 16 is constructed of two elongated 
side frame members 20 of substantially equal length, and four elongated 
end frame members 22 also of substantially equal length, although 
generally shorter than the side frame members 20. The side and end frame 
members 20 and 22 are joined at 120.degree. angles by six corner brackets 
24. 
The frame members 20 and 22 are preferably of the same tubular 
construction, and may be secured to the corner brackets 24 by fitting over 
projections from the corner brackets 24 as will be discussed in greater 
detail hereinafter. By using this construction, any size hexagonal frame 
16 may be produced by selecting two side frame members 20 and four end 
frame members 22 of the desired lengths and joining them with six corner 
brackets 24, and a regular hexagonal frame 16 may be produced by selecting 
both side frame members 20 and end frame members 22 of the same length. 
A superstructure, indicated generally by reference numeral 26, is 
constructed of six corner ridge members 28, a central ridge member 30 and 
two ridge joint members 32. The superstructure 26 is constructed upon the 
frame 16 such that the central ridge member 30 is spaced from the plane of 
the hexagonal frame 16 and disposed generally parallel to the longitudinal 
axis of the frame 16. Each end of the central ridge member 30 is supported 
by three corner ridge members 28. The corner ridge members 28 are secured 
to the end of the central ridge member 30 by a ridge joint member 32. One 
end of each corner ridge member 28 is received in a slot 34 in the ridge 
joint member 32, and the other end of the corner ridge member 28 is 
received in a slot 36 in the corner bracket 24. The central ridge member 
30 is secured in a slot 38 in the ridge joint member 32. 
As viewed in FIG. 2, the slots 36 are each arranged in a direction which 
bisects the 120.degree. angle formed by the corner bracket 24, and the 
slots 34 are arranged at 60.degree. angles with respect to each other in 
order to cooperate in a straight line relationship with the slots 36. In 
order to support the central ridge member 30 in a spaced relation from and 
parallel to the plane of the hexagonal frame 16, the corner ridge members 
28 are inclined at an acute angle with respect to the plane of the frame 
16, and the slots 34 and 36 are arranged to accomodate the angularity of 
the corner ridge members 28 as will be described in greater detail 
hereinafter. 
The superstructure 26 may be constructed upon any size frame 16 by 
selecting the desired lengths of corner ridge members 28 and the central 
ridge member 30. The ridge members 28 and 30 may then be assembled with 
the ridge joint members 32 to form the superstructure 26 which may then be 
mounted upon the corner brackets 24. 
A covering material or fabric 40 is disposed over the superstructure 26 and 
secured to the frame 16 by any suitable means. The covering material 40 
must be readily permeable to sound and must be capable of retaining a neat 
appearance conforming to the shape defined by the superstructure 26 and 
frame 16 for an extended period of time. Toward these ends, the fabric 40 
is preferably a knitted polyester fiber. Further, the fabric 40 may be 
stretched over the superstructure 26 and secured to the back of the frame 
16 by an adhesive. 
An alternative embodiment of the present invention is illustrated in 
exemplary FIGS. 3 and 4. In this instance, the grille 10' is also of the 
non-planar type similar to that previously discussed in connection with 
the grille of FIGS. 1 and 2, and parts of the grille of FIGS. 3 and 4, 
which find substantial correspondence in structure and function to those 
previously discussed in connection with FIGS. 1 and 2, have been 
designated with corresponding primed referenced numerals. 
The grille 10' is mounted on the front of a cabinet 12' and includes a 
generally planar frame 16' which conforms with the shape of the cabinet, 
which in this instance is rectangular. The grille 10' has a non-planar 
outer surface 18' which includes four generally trapezoidal inclined 
surfaces 42 and a rectangular surface 44 which is spaced from and 
generally parallel to the plane of the frame 16'. 
The frame 16' is constructed of two elongated side frame members 20' of 
substantially equal length, and two elongated end frame members 22' also 
of substantially equal length, although generally shorter than the side 
frame members 20'. The side and end frame members 20' and 22' are joined 
at 90.degree. angles by four corner brackets 24'. By using this 
construction, any size rectangular frame 16' may be produced by selecting 
two side frame members 20' and two end frame members 22' of the desired 
lengths and joining them with four corner brackets 24'. A square frame 16' 
may be produced by selecting side frame members 20' and end frame members 
22' all of the same length. 
The superstructure, indicated generally by reference numeral 26', is 
constructed by four corner ridge members 28', each of which is received at 
one end in a slot 36' in the corner brackets 24', and at its other end 
supports one corner of a generally rectangular ridge structure including 
two longitudinal ridge members 46 and two transverse ridge members 48 
which are connected to each other and to the corner ridge members by four 
ridge joint members 32'. Each ridge joint member 32' is arranged with two 
slots at 90.degree. angles for receiving the longitudinal and transverse 
ridge members 46 and 48 and a third slot for receiving the upper end of a 
corner ridge member 28'. 
The superstructure 26' may be constructed upon any size frame 16' by 
selecting the desired length of corner ridge members 28', longitudinal 
ridge members 46 and transverse ridge members 48. The ridge members 28', 
46 and 48 may then be assembled with the ridge joint members 32' to form 
the superstructure 26' which may then be mounted upon the corner brackets 
24'. 
A covering material 40' is disposed over the superstructure 26' and secured 
to the frame 16' by any suitable means. The covering material forms the 
trapezoidal and rectangular surfaces 42 and 44, and each of the ridge 
members lies at the apex of a dihedral angle thereby forming the 
non-planar surface 18'. 
Another alternative embodiment of the present invention is illustrated in 
exemplary FIGS. 5 through 12, and as discussed connection with FIGS. 3 and 
4 above, parts of the grille of FIGS. 5 through 12, which find substantial 
correspondence in structure and function to those previously discussed in 
connection with FIGS. 1 and 2, have been designated with corresponding 
primed reference numerals. 
The grille 10' is mounted on the front of a generally rectangular cabinet 
12' and is comprised of a rectangular frame 16' and a non-planar outer 
surface 18'. The frame 16' is constructed of two side frame members 20', 
two end frame members 22' and four corner brackets 24' in the same manner 
as described in connection with the embodiment of FIGS. 3 and 4 above. 
A superstructure, indicated generally by reference numeral 26' is 
constructed of four corner ridge members 28', a central ridge member 30' 
and two ridge joint members 32'. The superstructure 26' is constructed 
upon the frame 16' such that the central ridge member 30' is spaced from 
the plane of the rectangular frame 16' and disposed generally parallel to 
the longitudinal axis of the rectangular frame 16'. Each end of the 
central ridge member 30' is supported by two corner ridge members 28' 
which are secured to the end of the central ridge member 30' by a ridge 
joint member 32'. One end of each corner ridge member 28' is received in a 
slot 34' in the ridge joint member 32', and the other end of the corner 
ridge member 28' is received in a slot 36' in the corner bracket 24'. The 
central ridge member 30' is secured in a slot 38' in the ridge joint 
member 32'. 
As viewed in FIG. 6, the slots 36' are each arranged in a direction which 
forms an angle A with respect to the end frame member 22', and the slots 
34' are inclined at an angle B with respect to an extention of the central 
ridge member 30'. Angles A and B are complementary angles. As can best be 
seen in FIG. 7, the corner ridge members 28' are inclined at an angle C 
with respect to the plane of the frame 16'. A raised portion 50 of the 
corner bracket 24' and an extending portion 52 of the ridge joint member 
32' are similarly inclined to receive the corner ridge member 28' in a 
straight line relationship. 
As in the embodiments illustrated in exemplary FIGS. 1 through 4, a 
superstructure 26' may be constructed upon any size frame 16' by selecting 
the desired lengths of corner ridge members 28' and the central ridge 
member 30'. The ridge members 28' and 30' may then be assembled with the 
ridge joint members 32' to form the superstructure 26' which may then be 
mounted upon the corner brackets 24'. A covering material 40' is disposed 
over the superstructure 26' and secured to the frame 16' thereby forming 
the non-planar surface 18'. 
As can best be seen in FIGS. 8, 9, and 10, the presently preferred 
embodiment of the corner brackets 24' is comprised of a body portion 54 
from which two projections 56 extend forming a 90.degree. angle. The 
projections 56 are arranged to be slidably received within the tubular 
frame members for attaching the frame members to the corner brackets. The 
slot 36' is formed in the raised portion 50 of the body portion 54. In 
order to receive the corner ridge member 28' in a straight line 
relationship, the top of the raised portion 50 and the bottom of the slot 
36 are each inclined at the angle C with respect to the plane of the frame 
16'. The body portion 54 of the corner bracket has an aperture 60 in the 
bottom thereof which communicates with the inner end of the slot 36' for 
receiving a lug 62 projecting from the end of the corner ridge member 28'. 
By this arrangement, the corner ridge member 28' may be securely fixed to 
the corner bracket, if desired, without use of any adhesive. 
As can best be seen in FIG. 9, the end view configuration or profile of the 
projections 56 is preferably shaped to conform with the shape defined by 
the inner walls of the tubular frame members 20' and 22'. Further, one 
side of the projections 56 may be tapered as at 58 for facilitating the 
assembly of the projections 56 into the tubular frame members 20' and 22'. 
The construction of the frame members 20' and 22' and the purpose of the 
taper 58 will be discussed in more detail later. 
The ridge joint member 32' is comprised of two extending portions 52 for 
receiving one end of a corner ridge member 28', and a central portion 64 
for receiving one end of the central ridge member 30'. For this purpose, 
one of the slots 34' is formed in each extending portion 52, and the slot 
38' is formed in the central portion 64. 
The bottom of each slot 34' is inclined downwardly from the horizontal at 
the angle C. However, the top of the extending portion 52 is inclined 
downwardly from the horizontal at an angle D which is greater than the 
angle C. This structure is provided so that when the corner ridge member 
28' is secured into the slot 34' and the fabric 40' is stretched over the 
superstructure 26', the material will bear only on the corner ridge member 
28', and not on the top of the extending portion 52. Similarly, the top of 
the central portion 64 is below the top of central ridge member 30' so 
that the fabric 40' will bear only upon the central ridge member 30', and 
not on the top of the central portion 64. In this way, as can be seen for 
example in FIG. 5, the contour of the ridge joint member 32' can not be 
seen from the front of the grille 10', and a neat and attractive trihedral 
angle 66 is formed at the juncture of the corner ridge members 28' and the 
central ridge member 30'. 
The ridge joint member 32' may be provided with an aperture 68 in the 
bottom thereof which communicates with the slots 34' and the slot 38' for 
receiving a lug 70 projecting from the upper end of the corner ridge 
member 28' and a lug 72 projecting from the end of the central ridge 
member 30'. As in the corner bracket described above, this arrangement 
allows the ridge members 28' and 30' to be securely fixed to the ridge 
joint member 32', if desired, without use of any adhesive. 
The frame members 20 and 22 are preferably of the same tubular 
construction. In this way, the frame members 20 and 22 may be cut to the 
required lengths from a single standard extrusion for forming a frame 16 
of any desired size. 
The frame members 20 and 22 may be of any desired external configuration, 
and the inner walls 74 (FIG. 13) of the frame members 20 and 22 define a 
shape that is similar to the above mentioned profile of the projections 56 
from the corner brackets 24. In this context, similar is used in the 
geometrical sense of having the same angles and ratio of lengths of sides. 
The sizes of the similar shapes defined by the inner walls 74 of the frame 
members 20 and 22 and the profile of the projections 56 are arranged so 
that the projections 56 are slidably received in the space defined by the 
inner walls 74 of the frame members 20 and 22 and fit tightly therein. 
In forming the frame members 20 and 22 so that the projections 56 fit 
tightly, it occasionally becomes difficult to manually insert the 
projections 56 into the frame members 20 and 22. Accordingly, it has been 
found useful to provide the projections 56 with the taper 58 for 
facilitating the assembly of the projections 56 into the frame members 20 
and 22. During assembly, the distal end of the projection 56 is inserted 
into the end of a frame member and pushed in until the end of the frame 
member contacts the body portion 54 of the corner bracket. The frame 
member may be held in position by any securing means such as a staple 76 
(FIG. 6), or, if desired, by any suitable adhesive. 
The side frame member 20 occasionally tends to bend inwardly under the load 
of the covering material 40 which has been stretched over the frame 16 and 
superstructure 26 and adhered to the frame members 20 and 22. The tendency 
of the side frame member to bend increases as the size of the grille 10 
increases. In order to prevent this undesirable bending, the frame members 
20 and 22 are provided with a locating ridge 78 which projects from the 
side of the frame members 20 and 22 facing the center of the grille 10. As 
can best be seen in FIGS. 6 and 13, the ridge 78 on the side frame member 
20 fits under the head of a locating pin 80 which is mounted in the front 
of the cabinet 12. Any number of locating pins 80 may be used wherever 
necessary to prevent the undesirable bending of the frame members 20 and 
22. 
In order to mount the grille 10 on the cabinet 12, each corner bracket 24 
as seen in FIG. 14, may include a mounting pin 82 which may include a ball 
portion 84, a shank or shaft 86, a shoulder 88 and one or more retaining 
projections 90. The mounting pin 82 may be secured to the corner bracket 
24 by being inserted through an aperture 92 in a wall 94 of the corner 
bracket 24. The shoulder 88 contacts one side of the wall 94, and 
retaining projections 90 emerge from the aperture 92 and bear against the 
other side of the wall 94 thereby holding the mounting pin 82 firmly in 
place. Each ball portion 84 of the mounting pins 82 may be received in a 
socket 96 (FIG. 7) formed in cabinet 12, thereby releasably mounting the 
grille 10 on the cabinet 12. 
The corner ridge members 28 and the central ridge member 30 may be formed 
of any rigid material, standard steel bar being the preferred material. 
The corner brackets 24, ridge joint members 32 and frame members 20 and 22 
may be fabricated conveniently and economically from moldable or 
extrudable plastic materials. 
When the grille 10 is assembled as previously discussed in connection with 
FIGS. 10 and 12, the structure forms a flexible, easily handled grille 
which is sufficiently rigid to provide protection of the loudspeakers in 
the cabinet, and any play which may exist between the ridge members and 
the corner brackets or ridge joint members is removed by the tension in 
the covering material 40 which is stretched over the superstructure 26 and 
secured to the frame 16. If additional rigidity is desired after the 
grille 10 has been assembled, any suitable adhesive can be introduced into 
the corner bracket and ridge joint members through the apertures 60 and 68 
respectively. 
From the foregoing, it will be appreciated that the grille 10 presents an 
attractive, non-planar appearance and also provides a rigid superstructure 
26 for the protection of the loudspeakers inside the cabinet 12. Further, 
the grille 10 can be fabricated conveniently and economically by selecting 
the desired lengths of frame members 20 and 22 and ridge members 28 and 
30, and assembling them with the required number of corner brackets 24 and 
ridge joint members 32. The same size corner brackets 24 and ridge joint 
members 32 may be used in fabricating any size grille 10, and various 
polygonal grilles may be constructed by providing corner brackets having 
different angles between the projections 56, and ridge joint members 
having the required number of extending portions 52. 
While several particular forms of the invention have been illustrated and 
described, it will also be apparent that various modifications can be made 
without departing from the spirit and scope of the invention.