Jul 1, 1997 12:00 PM
Every thought, calculation, spec and design you produce for a specific jobculminates at the installation site. It's where your best efforts arebrought to life in the finished system. We enter the shell of anuninhabited building to install the system the occupants will work, worshipor live with. We build that framework around them to provide the servicesand amenities they need. That installation process is the essence of ourtrade. The install is fundamental, yet complex. For every hands-on skill ofthe trade goes into it: wiring and cabling, rigging and flying, designinghow the rack components will be used most efficiently, testing andmeasurement. It's on this principle that we dedicate each July issue to adifferent element of the installation. Last July, it was wiring andcabling, and this year we continue the tradition with testing the installedsystem.
Whether you're a contractor checking out a new system before operation or atechnician taking charge of an old system that must be evaluated in place,you must be able to see how a system actually works. Is is meetingexpectations, or is something slightly off? How do you find the problem inthe myriad details of an extensive sound system?
With testing - setting up a systematic check-out procedure that verifiesthe system is operating at the level of performance expected from thedesign. We lead off with Testing the Installed Sound System by Pat Brown.This article shows how to identify simple problems, from grounding tointerference to coverage, that ruin the sound of your system, and shows howto correct them.
We then turn to the actual tests used to verify performance. In What areour performance goals?, Bob Thurmond explains that although the contractorcan't evaluate the subjective elements of a system, he can provide betteroverall quality with today's sophisticated measurement techniques. Next, welook at frequency response. Jeffrey A. Rocha's article, The AmbiguousFrequency Response, covers how a loudspeaker will respond in the actualinstalled environment. Rocha gives an in-depth analysis of why the BDPR,not axial response, determines a loudspeaker's performance.
Dennis Bohn illustrates why proper setting of a system's gain structure iscrucial to producing good sound. In his article, Setting Sound System LevelControls, Bohn explains that a system's high cost doesn't ensure good soundif the settings are incorrect.
Finally, we'll look at peak limiters in Tom Walker's article, Is There aBetter Way to Set Limiters? Walker outlines the problems with limitersetting and providing maximum output without going over.
Testing, identifying and, most important, solving the many problems thatmay arise after a system is installed can be a daunting task. Theseinstallation technologies features, which focus on evaluation of theinstalled system, provide answers to some of the faults that turn up duringthe testing procedure - a procedure critical to the success of every soundsystem. We hope this July issue, and the July issues in years to come, willprovide useful information for the contractor, technician and othersconcerned with the subject of installation technologies.