Value, Quality & Service since 1980
One Box Array - The Church Speaker
A look at Speaker Coverage Angles
- . Church sound starts with the speakers. Some discussion
has been given to a so called "Sweet Spot". While somewhat relevant,
this disregards the most important factor - Coverage Angles.
- . The fact is, No combination of conventional speaker
cabinets will ever properly cover a typical rectangular church from an
oblique angle. In other words, hung overhead and
- . Conventional speakers typically have a coverage pattern
of 90° wide by 40° high. This is designed to be used at slightly
above head height, like on a tripod speaker stand, and vertically straight.
Tilting down creates a narrow stripe of coverage that will only reach a
few rows of pews in a church. Stacking these will increase the vertical
coverage, but will not provide the increased projection needed for the
back of the room. Hanging them sideways will give a taller vertical pattern,
but will NOT give the increased directivity needed for the back rows. Placing
them side-by-side will only make matters worse than ever.
- . The One Box Array was conceived to address the coverage
angle requirement for MOST typical churches of rectangular shape with a
high ceiling. By combining three DIFFERENT horns; 90°, 60° and
40°, the front, middle, and back of the room can be uniformly covered
with a minimum of cost, weight, and size.
- What about a line array?
- . With the exception of the very expensive "Room-Match"
series from BOSE, which are so expensive that most churches cannot even
consider them, most "Line Array" cabinets do not have different
directivity. They are designed for concerts and outdoor applications.
- . To cover the rectangular church, the front must be
wide and the rear must be narrow and the middle must be, well, medium.
This is clearly very simple with 3 horns of different patterns, all using
the same drivers, and same filter frequency too.
| Room Coverage - The 3 shaded
areas show the coverage patterns of each horn. . The cabinet is tilted
- The Room:
From the point of view of the speaker, the seating area
is not a square or a rectangle, it's a trapezoid, wide at the bottom and
narrow at the top.
And farther away to the back requiring more projection
or higher directivity, therefore a narrower pattern.
This is why no conventional speaker will give proper coverage
The 1BA, One Box Array, hung in a typical "A"
The resulting coverage was pleasantly uniform from front
to back and side to side, even in the balcony.
It is hanging 2 feet down from ceiling to reduce resonance
Frequently we see speakers hung too high, thus creating
unwanted interaction with the ceiling and beams
- The Box:
Side view of the cabinet.
The slanted speaker boards are 20° apart. This gives
enough overlap between patterns for smooth coverage.
The horns are rated for 40° vertical, but the primary
on axis pattern is really more like 20°.
The grille frames are 3 separate frames with tapered sides
and the outside edges can be chamfered or rounded for a better look.
Then they are covered together as one large frame. This
allows them to bend around the front 3 faces for a nice finished look.
The cabinet side layout dimensions.
The front speaker boards are recessed an extra 1/8"
for the carpet on the speaker board.
I always carpet the speaker board instead of paint. It
creates a nice gasket for the speaker and horns plus it eliminates reflection
and refraction from the speaker board surface.
Note: These sketches are not meant to be complete plans,
but if you know woodworking you should be able to build one easily enough.
I mostly filled the cabinet with fiberglass insulation
to reduce standing waves and increase internal air density.
I used a little push terminal cup for wiring. This is
much easier than a connector, and makes a better contact too.
Each speaker board with dimensions and speaker/horn placement
These are the 3 horns I used.
Sadly no company makes a consistent series of horns of
90, 60, 40 degrees with matching size and mounting cutout.
Note: If you need a 120° horn, the Selenium HC23-25
is a really nice sounding choice, perfect for smaller or wider rooms, or
with a lower ceiling.
A simple filter design: . (I never liked the term crossover
since nothing really "crosses over" anyway.)
More complicated filters just waste power. There is no
reason to keep the highs out of the 15" speaker, and this gives plenty
of protection to the HF drivers. . It actually comes out with a pretty
If you use good components, you will have a good sound.
3.3 mfd 400 volt Polypropylene capacitor
The finished cabinet with speaker and horns mounted.
Note: Middle horn shown is Eminence LT-250, now discontinued.
It looks like it is mounted the wrong way but is actually
correct. . The PRV WG17-25 is functionally the same.
Finished cabinet with grille.
The grille is attached with finish nails right through