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.