ISP
Line Array System installed in Living Stones Church
ISP Solves “The Dome” Problem 
ISP Technologies, utilizing their proprietary LINESIM™
software program, has designed a custom line array system
for the 3000-seat Living Stones Church in Alvin Texas. The
Living Stone Church presented a formidable challenge in the
design of a high performance sound system. The structure of
the church is a round dome of 88-foot diameter, with a
100-foot distance from the front podium to the sound booth
at the rear of the dome. It is obviously desirable to keep
as much of the sound energy off the dome as possible, yet
achieve a horizontal dispersion of 180 degrees.
ISP therefore, decided to custom design a 25,000 watt
Reference Line 210 Speaker system with multiple boxes in a
vertical line. Individual Line Array boxes have very narrow
dispersion in the vertical direction at high frequencies,
but wide vertical dispersion at low frequencies. The narrow
vertical dispersion at low frequencies is achieved by a long
line of boxes, with a longer line having tighter dispersion
at lower frequencies. Once the wavelength of the sound
becomes longer than the line length, the dispersion broadens
out. Because of this tighter, more uniform vertical
dispersion, our line array provides superior performance in
the Living Stones Church. The boxes are over 5 feet in
height (5 boxes per side), and so will maintain vertical
dispersion control to below 200 Hz.
The subwoofers, which handle frequencies below 100 Hz, are
floor-mounted boxes, which afford no vertical dispersion
control.
Most line arrays built by other manufacturers use small cone
speakers up to about 1.5 KHz (or higher). These are usually
allowed to have wide vertical dispersion, so that a
particular seat hears the summation of many of them (this is
needed, since they are low efficiency devices). But this is
self-defeating, since the curvature of the array and the
shorter wavelengths at these frequencies mean that the
summation is not in phase, which results in a severe
response dip in this region (the missing midrange). This is
also combined with the fact that cone speakers “break up” in
this frequency region, meaning the cone does not move like a
solid piston, but rather like a wet noodle, which results in
notches in the response and lack of clarity in the sound. To
get around this, the ISP Technologies Reference Line 210
speaker uses a compression driver with a 4-inch voice coil
and 4-inch diaphragm in the critical 700 Hz to 2.5 KHz
region. Its diaphragm does not break up in this frequency
band. Also, it is coupled to a horn with well-controlled
vertical dispersion, so that any person in the audience
hears only one or two of these devices, avoiding response
dips due to phase cancellations. The result is midrange
response smoothness and clarity that surpasses all other
line array in this price range.
The high frequency performance of the Living Stones system
is exceptional, due to the choice of drivers used and the
sophistication of the acoustic lens/horn devices. These
drivers use polyester diaphragms, as opposed to titanium
that “ring” and can produce an annoying high end. Also,
their 1.75 inch diaphragms and 1-inch throat sized are small
enough to achieve extended frequency response and wide
horizontal dispersion. The acoustic lenses focus this energy
in a very tight vertical pattern, so that multiple drivers
do not interact, which would result in peaks and notches in
the high frequency response. Finally, the horizontal
dispersion the Reference Line 210 speakers have, has been
carefully designed to be exceptionally wide (up to 120
degrees).
The Music Director at Living Stones wanted to achieve an spl
of 110db at 60 feet and the Custom Designed Reference 210
Line Array System delivered. With headroom to spare and
ruler flat response, the Reference Line Array delivered
115db spl at 60 feet. The most common comment upon hearing
the system was “WOW”. To find out how to order a Custom
Designed System, or any ISP product, contact ISP
Technologies at 248-673-7790.
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