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May 2012

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by Bruce Borgerson

Selecting and placing microphones for best effect is both an exacting science and a subtle art. True, the rules of physics cannot be broken. At the same time, we must make allowances for aesthetic tastes, and for varying budgets. Remember, all microphone types and models will sound-if only ever so slightly-different. And there are thousands of them.

Not surprisingly, complete books have been written on the subject, as well as lengthy chapters in guidebooks on church sound. So here we'll focus narrowly on some basics for the most common worship applications.

Define Your Terms: We'll start with a review of terms to be used throughout.

• Omnidirectional - Sound is picked up from all directions equally.

• Unidirectional - Sound is picked up from one side only. Most common types are cardioid and hypercardioid: cardioid rejects most sound from the rear, but picks up more from the side; hypercardioid picks up more from the rear, but has a narrower "cone" of pickup toward the front.

• Bidirectional - Also called "figure 8," these pick up sound from two opposite directions, but reject sounds 90 degrees off axis.

Finally, most microphones use one of three transducer types. No room here to detail the technology behind each, but we'll note key application differences. First, I'll introduce an acronym: IGAARAEE. It stands for, "in general, as a rule, all else equal." In other words, there will be exceptions.

• Dynamic - Sizes range from large to small. Most pickup patterns are cardioid or hypercardioid. IGAARAEE, dynamic microphones are the least expensive type, and are the most durable. But they are also the least sensitive, and exhibit the most restricted and least consistent frequency response, particularly in higher frequencies.

• Condenser - Sizes range from large to micro. Pickup patterns can be any, though bidirectional models are expensive. Again IGAARAEE, condensers tend to be more expensive than dynamics, are more sensitive to shock damage and moisture, and wired models require phantom power. But they can be very sensitive, with extended and very flat frequency response.

•Ribbon - Until recently, ribbons were considered too fragile for live sound, but recent models are more robust. Sizes are large to medium, and although inherently bidirectional, ribbons can be configured as directional. IGAARAEE ribbons are the most expensive type, but they are prized for a flat, smooth, "mellow" sound.

Regardless Of The Mic Or Application, Observe These Three Rules.

1. Place the microphone as close as possible to the sound source while still keeping all desired sounds inside the pickup pattern and not overloading the mic.

2. Observe the "3-to-1 rule." When using multiple microphones, make sure the distance between microphones is at least three times the distance from the microphone to the sound source. This avoids destructive comb filtering that results from the same sound hitting different mics at different times.

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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.