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Self-powered Loudspeakers. Thinking inside the box.
Innovation on self-powered loudspeakers has continued with lighter, more efficient and more powerful designs.
One of the most significant changes in the history of loudspeaker design and development has more to do with amplification than with the speaker drivers themselves. That was the development of the self-powered loudspeaker, which integrated the amplifier package into the loudspeaker enclosure.
The paradigm shift occurred in the mid 1990s when self-powered systems were presented as commercially viable products for live sound use. Covering separate market segments with Meyer Sound's MSL-4 for large-scale systems and the compact and multipurpose JBL EON, self-powered systems had progressed beyond the largely experimental tries at installing an off-the-shelf amplifier into a loudspeaker cabinet. These were purpose-built systems with a dedicated control electronics/amplifier package designed to work specifically with the other components in the system.
The advantages quickly became obvious to the marketplace. "Self-powered systems eliminate variables associated with traditional systems, such as remote amplifiers, processing, amp rack wiring and setup," notes Bob Langlois, Meyer Sound's senior technical support representative. And Jon Sager, senior manager of installed sound for JBL Professional, adds, "The need for an amplifier room is non-existent. This means the church will not need a dedicated room for the amps, eliminating the need for dedicated HVAC to the room, added cost of equipment racks, long speaker cable runs and the larger size of conduit to get signal to the loudspeakers. This reduces the cost of installation and operation."
Other benefits, while not readily apparent, are just as valuable as Gerry Tschetter, vice president of marketing with QSC Audio Products LLC, points out, "When a loudspeaker engineer designs an externally powered loudspeaker, it has to be built to withstand unknown drive power. When an amplifier engineer designs an amp, it has to be protected against unknown loads. But when an engineering team creates a well-designed powered loudspeaker, every element is known. So every element can be cost- and performance-optimized. Signal processing can be fine-tuned to protect the loudspeaker and get the most from the system's acoustical design."
The result is performance that is predictable, consistent, and a system that's easier to set up and harder to blow up. "Self-powered systems can be less prone to user error. For example, a volunteer might see a rack of amplifiers and processing and say, ‘How do I just make this thing go? How do I pass audio through this?' If you're not a pro audio person, a self-contained powered speaker makes it easier to get from A to B more quickly without having to navigate the signal chain in as much detail," says Guy Low of Electro-Voice.
Failure is not an option
On the other hand, though, "The obvious disadvantage is that the amps and processors will be up in the air with the loudspeaker systems. This makes for a more difficult situation should there be a failure," Jerrold Stevens, director of EAW's Application Support Group (ASG), points out. A valid concern-but as Sager notes, "One could argue the same challenges would exist if a transducer were to fail."
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Mark Johnson is an independent technical trainer/writer based in Crockett, Calif., and former editor of Sound & Video Contractor and Church Production magazines. He can be reached at mjohnson6286@sbcglobal.net.
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