It's a similar situation when choosing loudspeakers. Remember, once those new loudspeakers are installed, rethinking your decision will be costly. This is not a casual date with a new microphone or effects plug-in. It will become, literally, a solid attachment.
For guidance in finding the right match, I've recruited four experts to assist me in “preinstallation counseling.” They are Chris Gille, CTO and chief systems engineer at Eastside Christian Church, Fullerton, Calif.; George Relles, owner of George Relles Sound, a regional rental and installation company in Eugene, Ore.; Andrew Stone, production manager and audio director at Church on the Move, Tulsa, Okla.; and Dustin Whitt, freelance audio engineer and co-founder of OwnTheMix.com.
Basics 1: Coverage
We have a general consensus among the five of us that, when choosing loudspeakers, the single most important factor is fitting the coverage patterns to your worship space and seating areas. Whitt puts it in a nutshell: “The trick here is to cover the entire audience with sound but have as little spill onto the walls and other reflective surfaces as possible.”
So your first job is to get drawings—both plan (horizontal) and elevation (vertical)—of your worship space. Figure out where you can put the speakers, and then use a protractor to see what angles are defined by drawing lines from the speaker position(s) to the edges of the seating area, side to side and front to back.
Then you need to find loudspeakers with a coverage pattern that's a close match. If you're lucky, and if you're happy with mono reinforcement, you may be able to cover the space from one central point with one speaker. In a smaller church with a rectangular shape, one speaker with, for example, a 60- by 40-degree pattern just might do the trick. If you can find one with the power and quality you need, this may be your best solution, particularly for speech intelligibility.
But that's rare. Churches with contemporary worship styles often prefer stereo, need more power, or both. That means multiple speakers at multiple locations. Now uniformity of coverage gets complicated.
“The transition areas where coverage patterns overlap are the most important parts of the system,” says Gille. “They usually cover a couple rows of seats, and can potentially have destructive frequency interactions that will make people sitting there think the system— or your mix—is lousy, painful or harsh.”
Relles elaborates: “When multiple speakers are needed to achieve desired coverage, interaction becomes a major consideration. Midrange and high frequency patterns should overlap as little as possible to prevent destructive comb filtering.”
So it's critical to choose loudspeakers—here considering line array as a single “loudspeaker” source—with patterns that will cover the assigned area but without overlapping the coverage from adjacent sound sources. What's the best approach for doing this? That question leads us to an important related matter.
Basics 1A: Point Source or Line Array?
The great majority of church sound systems today use either point-source cabinets or modular line arrays. Which one is right for your church?
At some risk of oversimplification, we can say that the further you need to throw sound straight back from the loudspeaker location, the greater the advantage of a line array. “Line arrays have the advantage of adding loudspeakers to gain more power without the deleterious effects of high frequency interaction from multiple point sources,” says Relles. “Line arrays are a good choice when high SPL is needed, re-quired horizontal coverage does not exceed 100 degrees, and narrow vertical coverage is desired to keep reflections off a ceiling.”
Relles adds that longer line arrays can offer directional control of low frequencies—the longer the array, the lower the sounds that are controlled. Although concurring in principle, Gille cautions, “Most churches don't need the benefits of line arrays. True, if they have seats 150 feet away, and can allow 20 feet to hang arrays, then they can take full advantage of arraying benefits for lower frequencies.”
Relatively wide and shallow rooms, on the other hand, realize scant benefit from line arrays. Here, a design using several point-source loudspeakers with welldefined horizontal patterns will yield better results. “Churches should look for small but high-quality speakers with tight coverage patterns so everything behaves where patterns merge at the seats,” advises Gille.
Visualizing Results
When using arrays or multiple point-source cabinets, it's helpful to actually look at how various loudspeakers will work in the room. One way to do this is with computer simulation software. A few manufacturers distribute software for their own products free of charge, but the “industry standard” program—EASE (or Enhanced Acoustic Simulator for Engineers)—must be purchased at a rather steep price. But EASE does allow you to visually compare the performance of options from different makers inside an architectural drawing of your church.
“EASE modeling and architectural layouts have become my greatest allies,” insists Stone. “In most situations I get into, the audio hang is part of the visual treatment, so applying EASE data lets me open up different avenues for position adjustments and see how this translates into the acoustics and the seating areas.”
Of course, now we're getting into advanced loudspeaker system design. You won't need EASE to choose speakers for a portable system, a basement youth hangout, or many smaller churches. But as the rooms get bigger and wider, adding multiple seating levels, the complexities mushroom. “As soon as two or three speakers are needed for vertical coverage at the needed volume levels, a professional system designer should be involved,” advises Gille.
Basics 2: Frequency Response
Once you've determined coverage requirements, you need to find loudspeakers that will best reproduce the program material you will be running through them. If the requirement is for spoken word only, then a frequency response from 500 Hz-4,000 Hz will do nicely. And if that's the case, one of the new generation of slender column arrays (see Church Production Magazine, May 2011, or www.churchproduction. com/columnarrays) might do the job.
But for music, you'll want to stretch response as close to the full 20 Hz-20,000 Hz audio bandwidth as you can get. That usually means a two-way, three-way or even four-way system. If you can't use speakers with 15-inch woofers, you'll probably need to add subwoofers to support deep bass for contemporary music styles.
Basics 3: Power Output
The next specification you need to look at is peak power output. This is given by the manufacturer in dB SPL measured at 1 m (3.3 feet) from the speaker.
For contemporary worship, Gille suggests a minimum of 90 dBA slow sustained at the seats, and with at least 10 dB of headroom above that. “With the inverse square law, when you halve the distance to the speaker, you add 3 dB,” notes Gille. “So if a cabinet needs to deliver 105 dB up to 48 feet, then it needs to measure 108 at 24 feet, 111 at 12 feet, and so forth. At an absolute minimum, then, you need a speaker specified 117 dB SPL at 1 meter. Most high quality speakers will have peak outputs of 120 to 140, revealing how ‘ready to rock' they are when paired with ideal amplifiers and processing.”
Beyond Basics: Passive or Active (Powered)
Once you've decided the basics, you need to determine if you want to purchase power amplification and drive processing (crossover, EQ, limiting) separately or bundle everything inside the loudspeaker.
Relles favors the packaged approach. “With powered speakers, the issues of impedance, crossover, damping factor, driver time alignment, speaker protection and amplifier matching are all designed into the system. In addition, you don't have to factor in losses from long speaker cables, and it is much simpler to zone and align individual loudspeakers because you don't have multiple speakers sharing the same amplifier.”
While concurring on performance advantages, Stone points out counterbalancing considerations. “You have to make sure the added weight of a powered system doesn't put you over your static weight limit,” he cautions, “which is definitely something to consider if you're revamping an older space. Also, here in the Midwest where thunderstorms are prevalent, the power grid can experience random hits. It's much simpler to replace an amp in the rack than one flown in an array up in the air.”
Two loudspeakers can share near identical specifications yet sound strikingly different. Two factors often at play are the type of high-frequency drivers and the overall linearity of the system.
Most professional loudspeakers used in churches will use compression drivers coupled to a horn (or special waveguide in line arrays), but a few will have ribbon (“planar”) drivers or dome tweeters.
“Ribbon drivers sound great, but they are not made to be pushed hard,” states Whitt.
“If your church likes to rock and roll, stay away.” I concur. We have ribbon HF drivers in our historic sanctuary, where they sound wonderful on choir and strings. But for contemporary worship in Wesley Hall, it's compression drivers all the way.
In the middle ground are a few smaller modular line arrays with dome tweeters for the highs. I've heard a couple, and they sound very good, even at moderately high levels.
Linearity is an important but slippery topic, as there is no single specification for it. A perfectly linear loudspeaker would maintain the same frequency response regardless of power level, maintaining the same sonic balance from very soft to very loud. Relative linearity requires careful listening comparisons to discern, though in general self-powered systems will have an audible edge.
Time to Listen
Let's assume you've narrowed your choices to a few prime candidates. Is it worth giving them a listen?
For low-cost portable systems, I've found that a session at a music retailer's showroom can be helpful. Do your homework first, and be sure to take either a good recording of your own music, or something nearly identical in style. When shopping for a portable youth system a few years back, we went in favoring one maker's product but came out with another—and have been happy ever since.
Hearing a closely similar system at another church or performance venue is also recommended. “I've always relied mainly on what I can hear vs. written specs on a PA,” says Stone. “I'm much more apt to specify a PA I've used in a similar situation, along with using recommendations of other trusted professionals.”
Gille recommends attending comparative “shootout” sessions staged at tradeshows. “They are getting great with all manufacturers playing well together,” he says.
The verdict is split on hosting your own shootout by inviting manufacturers' representatives or dealers to set up in your church. “Shootouts are useful when done in your room using actual program materials,” claims Whitt. “However, in situations where a manufacturer has a competitor's speaker set up in their own demo room, be wary of what they might be doing behind the scenes to skew the results.”
Stone demurs: “After attending many shootouts over the years, I've never really found them to be that useful, other than seeing a lot of nice PA at one time.” Gille is similarly skeptical: “I don't recommend hosting your own shoot-out. It's too messy for everyone, and a long list of variables after the fact will still leave some wondering.”
A Final Word on Priorities
When it comes down to final selection, and if budget becomes a sticking point, Whitt offers a few parting words of counsel: “Speakers are the final link in the audio chain, and everything goes through them. If you save money on a cheaper microphone or compressor, it only affects part of your sound. If you try to save money on speakers, it affects 100% of the overall sound. Make speakers the last place you cut costs in the sound system,” he closes.
