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May 2012

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New Alternatives to Line Arrays

Line arrays are the hottest loudspeaker development in the past decade. But are they right for your church?

by Bruce Borgerson

A mere decade ago, modular line arrays were essentially nonexistent as the primary sound reinforcement system in worship auditoriums. Over the past five years, however, line arrays have mushroomed into the hottest trend in loudspeaker systems – to the point where traditionalists might label it a fad, Unquestionably the change is apparent in the pages of this publication. By intention or not, it seems most of the AV systems profiled recently have shown photos of the near-ubiquitous, gently curved “banana” of line array loudspeaker systems.

But is a line array always the best solution for your new, refurbished, or expanded worship auditorium? It all depends, according to leading audio system designers surveyed by Church Production. But, before we get to their cogent analysis, we’ll first review how line arrays differ from conventional or point-source systems.

Go Bananas – or Not

In its simplest terms, a line array is a vertical stack of loudspeakers deliberately designed so that the sounds from the separate loudspeaker cabinets combine, or interact. This has two benefits: it controls the vertical coverage, and also throws sound farther than is possible with conventional loudspeakers. Almost counter-intuitively, the longer the line array, the more the vertical coverage is restricted – or “flattened out” – across the audio spectrum. Essentially, the line array creates a uniform, wide (usually 90 to 120 degrees) wavefront that is squashed into a flat wedge of sound. Ideally it will push the same volume level nearly twice as far as with conventional designs. However, following the strict laws of physics, to make this work at lower frequencies you need a long line array. For example, for pattern control down to 125 Hz (about low C) you need a line array over nine feet long.

The alternatives are conventional loudspeakers, also called “point source” or “point and shoot.”

These systems are designed so that the sounds from separate cabinets do not interact, even if arrayed or clustered adjacent to each other. Each cabinet works like an individual sound “spotlight,” and if arrayed you’ll often see significant splay angles in between to prevent patterns from overlapping. In this case, overlap causes undesirable “hot spots” and “dead spots.”

An Obvious Case

If you want to throw powerful sound over a distance, and your audience is all on one relatively flat plane, then a line array is clearly your best solution. A case in point: outdoor music festivals, the louder ones in particular. For the main system, nothing else makes sense. However, the less your worship space resembles a festival layout,, the more you may want to consider the alternatives.

“In a room that is quite wide but not very deep, line arrays tend to be more expensive and not work as well,” explains Ryan Knox, a senior consultant at Acoustic Dimensions in Dallas, Tex. “The other place they tend not to work so well is when you have a large vertical angle of coverage, such as with high balconies. In tall rooms, you may need a lot of line array boxes to cover what you could with two or three conventional ones. Line arrays work best with a fairly narrow opening angle.”

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Bruce Borgerson networks around the industry via Wavelength Communications while monitoring technologies at the First United Methodist Church of Ashland, Ore.