Input Devices : How to Run Church Audio 101

The first part of knowing how to run church audio is knowing the equipment.  In the simpliest form, a person sings into a microphone.  The microphone then sends the audio signal to the sound system.  The sound is then processed and amplified and sent out to the speakers which then turns the audio signal into sound waves.  Therefore, there are input devices, processing devices, and output devices.  This article covers the types of input devices.

Input Devices

Input devices include vocal and instrumental microphones, DVD players, CD/Tape/mp3 players, VHS players, guitar amps, bass amps, and anything else that produces sound!  Let’s say the pastor wants to play a video presentation via the laptop.  The audio will come from plugging the computer’s audio out into the sound board.  Thus, even a computer is an audio input device.

Saying "microphones" as an input device is like saying "four-wheeled motored object" as a type of vehicle.  Microphone is a very generic term.  There are different types of microphones and they each have something that makes them unique in the types of sounds they detect and the environments in which they can be used.

Microphone types include dynamic microphones, condensers, and ribbons. 

Ribbon microphones are used primarily in recording studios due to their fragility.  They produce a wonderful warm sound but have internal components that can easily break. 

Condenser microphones require a power source known as phantom power.  They can be battery-charged or in a charged state but most require the external power source.  These microphones are not good for high volume sounds but do excel at high frequency response.  These might be used on an acoustic piano, acoustic guitar, and cymbals.

Dynamic microphones are the most common general-purpose microphones.  They do not require phantom power.  They can withstand high sound pressure levels (high volume from the source) without damage or distortion.  Traditionally, these types of microphones are not known for producing a good response for high frequencies which can run over 10 kHz.  These are used on objects like drums, vocals, and guitar amps.

Instrument amps are listed as both as an input device and an input device with microphone usage.  Instrument amps like the common bass and guitar amps produce a sound signal.  All of these amp’s have at least one speaker for sending out the sound.  However, for more control over their sound, the sound operator (you) have a few options.  First, you can use a dynamic microphone to "mic the amp."  Using this method, you are pulling in the sound that is send out from the speaker.  Another option is to plug the amp directly into the sound system.  Some amps have an output jack.  Using this jack, the sound goes out through the jacked cable but does not come out through the amp speakers.

Microphones use a standard "XLR" cable for connecting to the sound system.  The typical scenario is the microphone cable is pulled into the microphone at one end and into a jack on the stage floor at the other end.  When dealing with lineout cables from amplifiers, these are usually 1/4" mono cables.  Using a DI (Direct Input) box, the 1/4" cable is converted into an XLR type which can then be plugged into the stage jack.

Microphones come in a variety of shapes and sizes depending on their use, such as a vocal microphone or a flute microphone.

There is also something called the polar pattern which determines where the microphone best detects sound.  This will be covered in a later article.

Input devices are connected to the sound board / mixing console.  Each input device occupies a single channel.  Input devices that output a stereo signal will occupy a stereo channel on the mixer.

Each input device produces a different input volume level.  When you are at the point of setting up the sound board for a service, you will be setting the gain/trim structure for each input.  Setting the gain (sometimes called Trim), you are setting an optimal input volume level.  Once you have set the gain levels, you will be able to set the fader for the channel at the infinity point (about 3/4 up the fader).  This gives you the most granular control over the fader.  See (insert link) for setting gain / trim.

Summary

These are the typical types of input devices.  When you understand how each works, you will be able to use the right microphones for the right sound sources.  Also by setting the proper gain levels, you will have more control over the incoming sounds.  Running a sound system is not only about what comes out of the speakers but how you control what goes into the system.