If you’ve ever tried to purchase a microphone for your church — for the pulpit, the choir, or for musical instruments — you probably know how many different types of microphones are on the market. Most have been designed for very specific uses, and explanations of the technology that’s been developed for each application can and does fill lengthy books.
Starting with the Basics
Microphones are classified into several basic types, and understanding their characteristics and specifications does require some technical grounding. Following are brief (and hopefully painless) descriptions of these characteristics, especially as they apply to churches.
A microphone’s transducer element is the mechanism that actually picks up sound and converts it into an electrical signal. The element type determines some of the basic capabilities of the microphone.
Dynamic type microphones have a relatively simple construction and are, therefore, economical and rugged. They can be made with good sensitivity and excellent sound quality over a fairly wide frequency range. From a practical standpoint, if the microphone is going to be handled extensively, or used for outdoor sound reinforcement or recording, a dynamic microphone would be first choice.
Condenser microphones employ a more complex technology that enables pickup of a wider frequency range, often with a more natural, high fidelity sound. Their construction includes a preamplifier and they require the use of a power source: batteries or “phantom” power which is a way of supplying power through the microphone cable, often from the mixer. Condensers are more complex than dynamics and tend to be somewhat more costly.
Frequency Response refers to the range (from lowest to highest frequency) that a microphone can reproduce, and to the variation of output within that range. Microphones are available with either a “flat” or “shaped” frequency response, each type suitable for specific uses.
Omnidirectional microphones can pick up sound from a wide area but cannot be aimed to favor one sound over another. When recording vocal groups, bands or orchestras, an omnidirectional microphone will pick up a unified sound without emphasizing one voice or instrument over the others. However, as part of a sound reinforcement or P.A. system, an omnidirectional mic may be more prone to feedback because it cannot be aimed away from loudspeakers.
Unidirectional microphones not only isolate one voice or instrument, but can also reject objectionable background noise. In addition, a unidirectional microphone — properly placed — minimizes feedback, even at high volume levels. For these reasons, unidirectional microphones far outnumber omnidirectional microphones in day-to-day use, both for recording and for sound reinforcement applications.
Another, relatively new, option is the Wireless Microphone System, which consists of a combined transducer/transmitter and a receiver. The transducer/transmitter picks up and sends audio signals via radio frequency to the receiver, which converts them back into audio signals. This signal is then input to a mixer or amplifier in exactly the same way as a signal from a cabled microphone. These are increasingly popular with preachers because of the freedom of movement they permit.
Because wireless microphone systems operate on basic radio principles, they are susceptible to “interference” and “dropout.” Interference results when your receiver picks up signals from sources other than your transmitter, such as signals from a local radio station or police car radio. Dropout occurs when the signal from your transmitter is physically blocked from reaching your receiver. A single syllable — or the entire transmission — can dropout if, for example, a metal wall is between the transmitter and the receiver.
A Few General Rules
In any application, these rules of thumb can help make the best use of your microphones.
– To determine a good starting microphone position, listen to the sound source as you move around near it. Put the microphone where the source sounds best to you — the microphone will “hear” what you hear.
– Place the microphone only as close to the sound source as necessary for good isolation, but not so close that the sound becomes unnatural.
– When multiple microphones are combined on a sound mixer, the distance between adjacent microphones should be at least three times the distance from each microphone to its intended sound source. This will help eliminate phase cancellations — a hollow sound. For example, if two microphones are each placed one foot from their sound sources, the distance between the microphones should be at least three feet.
– To prevent interference in a wireless microphone system, discuss the potential for this kind of problem with your supplier before you buy, particularly if your church is located in a large urban area with many and varied radio transmissions on a wide range of frequencies. The exact transmission frequency of your wireless system can be set (often only at the factory) to avoid interference in your area. Some manufacturers offer special frequencies for operation in extremely difficult locations.
– To prevent dropout in a wireless system, the preacher (or other microphone user) should remain as close as possible (within 300 to 400 feet) to the receiver, with a clear, unblocked transmission pathway. If this is impossible, you might consider a “diversity” wireless system. Diversity systems provide two antennas on the receiver, along with circuitry that will select and use the stronger signal. Some diversity receivers allow remote placement of the two antennas, so that they can be widely separated to pick up signals from a large area.
Mic Placement for “Natural” Sound
The type of microphone you buy is an important factor in quality sound reinforcement, but it’s only the first step. The positioning of the microphone in relation to the sound source also affects overall sound quality.
The suggestions listed here for microphone placement should produce a natural sound in most environments. However, if feedback is a serious problem in your church, if you prefer an especially “bright” or more “bassy” tone, you may have to experiment until you get exactly the sound quality you want.
For the pastor, I recommend a undirectional, gooseneck condenser type for the pulpit or lectern, and a undirectional, boundary condenser mic for the altar. If you are very active in the course of your service, an omnidirectional, wireless lavalier microphone might serve best.
A gooseneck microphone can be installed in the pulpit where it is most convenient and unobtrusive; the flexible neck allows for adjustment to the height and position of the speaker. A unidirectional boundary microphone will pick up sound in an area several feet in front of it and a few feet above it, and should be positioned on the altar accordingly.
For best results with a lavalier microphone, mount it in a tie-bar clip, then attach it to the preacher’s clothing six to eight inches below chin level.
