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Buying and Placing Mics

Critical steps for ensuring sound excellence during worship

Microphones are the first—and most—important link in the audio chain. By selecting the right mic for the situation, and positioning it well, a church can dramatically improve its worship service experience.

Churches of any size can become better at buying and placing mics. Regardless of whether the budget allows for paid staff members to ensure the excellence of audio, or a team of volunteers is charged with the task, basic principles and practices can make a big difference.

The mic "creates success for a volunteer-driven ministry," says Wes Hartley, media pastor at Lake Pointe Church in Rockwall, Texas. And the same is true for a staff of pros involved with sound ministry.

Mics range in size from a few millimeters to more than a foot and come in a bewildering array of shapes and designs. However, they all serve one purpose: to convert acoustical energy into electrical energy to be used in a sound system. When applied correctly, they perform this singular task well, with clear, intelligible vocals, smooth instrument reproduction, and added clarity throughout the signal chain.

In order to achieve this goal, it is important to gain a working knowledge of mic design and usage. With insight from industry experts and some practical guidelines, church leaders can choose the right mic for any application they may encounter.

Two Designs

Live production microphones typically fall into two operating principle designs: dynamic and condenser. The dynamic mic is the male of the species, with a robust functionality and simplified structure. It generates signal through a moving coil of wire placed inside a magnetic field. The incoming sound pressure hits a diaphragm sitting atop the coil, causing piston-like movement and a corresponding electrical output. Because the dynamic mic relies on a straightforward mechanical process, it is highly reliable and it is able to withstand tremendous incoming levels. But its inherent mass creates a lag in response time and an inability to capture distant sources.

The female of the species, the (back electret) condenser, uses electronics to bolster the small signal that its charged diaphragm detects. Thus, it is more adept at detail and clarity. Unfortunately, those same electronics make the condenser generally more expensive and fragile than a comparable dynamic.

As in life, the male and female mics are complementary to one another, each providing a particular skill set. As with all things technical, the application drives the selection, for if the source is the youth band, dynamics are in order, but if the event is a violin duet, condensers rule the day.

Following the Patterns

Both dynamics and condensers can use any of four popular response plots, or areas of sensitivity, termed polar patterns.

An omni-directional mic, as its name implies, will respond to sound from any direction. Omnis are usually small and exhibit a smooth response from lows to highs.

Unidirectional mics encompass a trio of polar patterns—cardioid, super-cardioid and hyper-cardioid—with a logical angle of acceptance from moderate to extreme from one to the other. Most unidirectional mics exhibit an exaggerated response to bass frequencies when the source is close to the microphone. Known as "proximity effect," this phenomenon can be used to deliver authority to a male vocal, or it may simply mask a vocal's clarity. A few products, such as Electro-Voice's Variable-D mics, effectively counteract this issue.

  • Cardioid mics are the most popular choice for use on church platforms, due to their rejection of sounds coming from the rear of the microphone. If a cardioid's polar plot is inverted, it resembles a heart shape, hence the term's connection to the word cardiac. A cardioid mic is most sensitive to energy "on axis," or in front of the microphone, and "nulled," or least sensitive, at the rear. Therefore, a vocalist on stage can achieve the highest gain-before-feedback with a cardioid by singing directly into the face of the mic and pointing the floor monitor at the mic's cable exit.

  • Super-cardioid and hyper-cardioid mics tighten their patterns beyond a cardioid's in order to reject more stage energy and increase on-axis response, but that comes at the expense of the cardioid's smooth, 180-degree null. Their null points move to approximately 125 degrees for the super and 110 degrees for the hyper.

Again, the choice of pattern falls to the intended use. For a contemporary worship leader on a loud stage, a hyper-cardioid mic will provide maximum rejection of bleed-through from nearby sources while increasing sensitivity directly in front of the mic. However, for a blended worship team meeting in a gymnatorium, a super-cardioid vocal mic will reduce the unpleasant sonic qualities of the room while still allowing the singers some freedom of movement side-to-side.

A typical handheld dynamic cardioid microphone, such as the Shure SM-58, is designed for close use (less than six inches) to the mouth and its construction follows suit with a tapered ergonomic handle, an integral pop filter to reduce plosive energy (also known as "p-pop energy"), and isolators to reduce noise. Sennheiser's e845 increases high-frequency response and moves the dynamic to a super-cardioid pattern for a slight price premium. For about $100 to $200, handheld dynamics represent an excellent value in sound quality. Dynamic instrument mics are often built in a probe shape to "reach" the intended source with a flat grille for easy positioning. Audio Technica's top-address ATM650, at about $150, is a prime example of an outstanding instrument mic design.

Condenser models, with their increased complexity, command a higher average price of $300 to $400, but prominent stage models, such as the classic AKG C535EB handheld vocal mic, are road-worthy and versatile enough to warrant consideration.

Area mics for choir and stage are almost universally condenser in nature and are available to suit a variety of needs. The Micro Series from Audix is an exemplary approach to choir mic design, sporting such novel developments as an integrated 50-inch or 84-inch carbon-fiber arm and the world's smallest self-contained balanced element. Astatic's similarly priced ($500) 1600VP choir mic adds to the technology base by including a remote box with user variable pattern control, from omni to hyper-cardioid and beyond, to precisely match the mic's response to the need.

Smart Placement

Proper placement is critical to realize any mic's potential. As Steve Savanyu, Audio Technica's director of educational services says, "location determines gain-before-feedback and the overall timbre of the generated sound."

Casey Johnson, a regional representative for Shure, agrees.

"Most live sound environments require the operator to use the mic as a defensive tool in order to reject as much of the undesirable noise as possible," Johnson says. "This approach makes it possible to create a clean signal at the console and requires less work downstream."

For stand-mounted mic applications, such as a guitar amp, both Savanyu and Johnson suggest using a dynamic cardioid mic, 1-inch off the grille, with the cable exit oriented toward the player's floor monitor to minimize bleed-through.

On a grand piano, Johnson recommends a condenser cardioid located at a 30-degree down angle, 2 inches behind the hammers and 3 inches off of the strings positioned slightly above middle-C, and pointed at the keyboard. If an extended low-end is needed, a second mic can be located off the bass strings in a similar fashion.

Gene Houck, national sales manager for Audix says it's possible to reinforce a choir.

"The key is to get the mic element above the singers and that requires height," Houck says. "While a flown choir mic makes sense in some situations, any church whose members move to different locales on the platform will benefit from raising the portable mics to 2 feet above the tallest person in the back row and separating each mic 3 times the distance the mic is to the source."

For podium-based sermon deliveries and announcements, Doug Gould, a respected industry expert, encourages churches to "install a flexible super-cardioid condenser mounted with an isolation ring and use the channel equalizer to remove frequencies below 150Hz with an additional cut around 400Hz."

Kent Morris is a media systems designer and technology instructor based in Atlanta and a contributing editor to Your Church.

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