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Microphone Basics
By Micah Boaz and Tim Waters

In the grand scope of worship, nothing is more important than getting the message to the audience. But, in today’s sound environment, the use or misuse of technology can easily get in the way. 

Here are a few of the more common challenges that most church sound people find themselves faced with regarding microphones.

What are some microphone basics?
A microphone is simply a device that converts sound (acoustic energy) into an electrical signal that can then be amplified and processed. You are likely dealing with two types of mics: dynamics and condensers.

A dynamic mic works much like a speaker, only in reverse. The diaphragm moves in response to the sound, moves a coil in a magnetic field, and produces an electrical current. This “mechanical” system requires no batteries or power and is extremely rugged. An added feature of dynamic mics is their ability to function in loud environments without distortion, making them preferred choices for drums, guitars and vocals.

Condenser microphones use an external voltage to charge a very thin diaphragm assembly. As the diaphragm moves in response to sound, the electrical output of the assembly changes, resulting in a usable signal. Because the diaphragm assemblies are so lightweight, they react to sounds much faster. To the ear, they are more sensitive and can process higher frequencies easier than a dynamic. Condensers tend to be favorites for cymbals, acoustic guitars, piano, and also vocals. 

One more thing about condensers—remember that they have to have an external voltage? Some condensers get this from internal batteries, but most are “phantom” powered.  Sounds spooky, huh? Phantom is nothing more than a voltage applied to the element through the mic cable. It is usually switched on at the mixer, but can be from an external supply, placed between the mic cable and the mixer input. Almost always, phantom is denoted on a mixer as “+48.” Keep in mind that phantom requires all three wires in the cable, so if you can’t get signal from your condenser and you know that phantom works, try switching cables.

 The last thing to think about with microphones is their “polar pattern.” This is nothing more than the shape of the “pickup” area around the mic. You are likely to be dealing with three types of patterns: cardioid, hypercardioid or omni. 

Cardioid, sometimes called directional, patterns largely reject any sounds behind them.  Why does this matter? If you prefer to have a floor monitor directly in front of you, a cardioid pattern would reject the monitor sound and prevent feedback. 

Hypercardioid mics are more narrowly focused to the front, but tend to pick up a little more to the rear – the result is that they can better reject sound from the sides. If you have a singer with a monitor on either side of them, the hypercardioid is best.  

Omnidirectionals, as you can probably guess, pick up from all directions – we’ll look at an application for these shortly.

Let’s move on to microphones for instruments. Entire books have been written on instrument micing, so let’s look at a few key points. Obviously, your goal is a great sound without feedback. Mic choices and placement can go a long way here. Let’s look at micing an acoustic guitar, for example. Consider that the player is sitting down, plays mostly strumming rhythm with a drummer on one side and a piano on the other. A small floor monitor is directly in front.

Cardioid, hypercardioid or omni? 
You can guess that an omni would pick up everything around your player, including the monitor (insert loud screeching sound, painful wincing and nasty looks). The cardioid, if pointed up toward the guitar, would reject the monitor, but might still get too much of the side instruments. Must be the hypercardioid, right? The narrow directionality “focuses” in on the guitar, but the rear pick-up may get some monitor. Use your knowledge of polar patterns to move the hypercardioid mic to point down at the guitar at about a 45 degree angle – the pattern is focused on the guitar, while the rear pickup lobe is aimed at the ceiling.

Dynamic or cardioid? 
Consider that the sensitivity and extended frequency response of a condenser is nice, but it is not vital in this instance. The player is primarily strumming, which tends to get loud and lends a percussive rhythm. Here, you use your most valuable tools of all – your ears. Dynamics, because they won’t overload, have a pleasant way of smoothing out sounds. Whatever instrument you are stage micing, try to mic as close as you can while still sounding natural, and use the natural properties of the microphone to prevent feedback and unwanted noise.

What about micing the choir?
Fortunately, form and function work together here. Condensers, because of their sensitivity and ability to be produced with such small elements, are natural choices. They can be hung from the ceiling and are virtually invisible. The most popular pattern choice is cardioid, to reject reflections from the back wall.

Generally, choir mics are hung 2 to 3 feet in front of the first row, at a height of 2 to 3 feet above the last row, pointed at the middle to back row. 

A choir will “blend” itself – all you need to do is capture what they are doing. A few mics properly placed and evenly balanced will do the job quite nicely. Just don’t forget to turn them down when the choir is not singing. Similarly, turn down any other unused mics when the choir is singing. In any circumstance, the fewer mics open at a time, the better.

What are the choices for speaker microphones?
Without question, the most popular choices here are clip-on lavalier mics and small headworn mics. Condenser technology allows mics to be so small and lightweight that they usually go unnoticed. Lavalier mics should be placed roughly 6 inches from the speaker’s chin. Your choice of pattern depends on the acoustics of your space. Some find that cardioid (directional) mics can tend to sound small and unnatural, as the ear expects to hear a small amount of ambience in any human voice. In very reverberant environments, this is less of an issue. An omnidirectional pattern tends to sound more natural, but may pick up reflections and possibly monitors. Generally, in a highly reverberant space, go cardioid. If less so, try an omni.

With the headworn mics, the pattern is a little less important because the element can be placed so much closer to the mouth, allowing for higher gain before feedback. This means that because the signal is naturally stronger, you don't need to turn it up as much, significantly reducing the tendency to feed back.

What about wireless systems?
In most instances, speakers and singers like to get out from behind a stationary mic and decide to go wireless. Don’t let these systems intimidate you; modern systems are really simple to use and understand. Each system includes a transmitter and a receiver – simple.  These operate on a specified frequency so that one receiver looks for signals from one transmitter – simple. The receiver connects to a line input on your mixer and is treated just like any other source. Just remember that each system must operate on a different frequency. To further simplify things, manufacturers provide multiple pre-programmed frequencies designed to work with each other.

In choosing to add wireless to your sound system, consider how many speakers or musicians will be wireless. Different systems have varying sets of frequencies available.  The ability to utilize more and more frequencies – and more systems – is one of the primary factors in varying levels of pricing. That said, just about any system will allow for two to five systems at a time.

You will see the term “diversity” used a lot in wireless system literature. This simply describes how the receiver looks for signals from the transmitter. In a diversity system, two antennas are looking for the same signal; the one that finds the strongest signal is used, helping to ensure a consistent reception. Look for this feature in a system.

Wireless systems are also described as either VHF or UHF. This is just like the channels on your pre-cable television. The VHF range got pretty crowded, so manufacturers moved to UHF, looking for more available frequencies. You are much less likely to encounter interference with a UHF system. Your wireless systems sales representative will help select a set of frequencies for use in your area.

With 30 or so people on stage, a house full of worshippers and teams of possible technical problems, keep in mind the reason that you are behind the board. Sound and A/V has been introduced and largely accepted into our worship sessions because they enhance the message that we’re conveying to our audience. Whether it’s a 140db soloist or an inaudible evangelist, your job is to repackage and deliver their message to your audience.

After all, if they can’t hear the message, they can’t GET the message.

This information was written by Micah Boaz and Tim Waters of WirelessMicrophones.com.