Functions

  Any control board or console serves five basic functions: to select, mix, amplify, monitor, and route an audio signal.

     An operator can select (input) various sounds at the same time. Most typical of the radio work accomplished with a board is to mix voice and music (or sound effects), as in production of a commercial.

     A board can also amplify any sound source. This allows an operator to properly balance sound levels, as when an announcer talks over music (where microphone volume must exceed music volume so the voice is clearly heard).

     Monitoring an audio signal can be either visual (by watching volume unit [VU] meters) or aural (by listening to speakers or through headphones).

     Finally, the control board is used to route (output) signals to a recorder, another studio, or the transmitter.

The easiest way to understand the operation of any control board is to look at one of its individual sound channels. Such a channel includes a group of switches, faders, and knobs in vertical alignment; each group controls one or two sound sources. The number of channels (boards typically have between 12 and 36 or even more) defines its capacity to handle multiple signals. Most boards allow more than one input (microphones, etc.) to be assigned to each channel, though only one can be selected at a time. Regardless of configuration, the first two channels (from the left) of any board are usually designed for microphones, which always need special amplification. CD players, audio recorders, and other equipment can be patched into the remaining channels.

For any channel, signals can be sent ("output") to one of three destinations: program, audition, or auxiliary. When "program" is selected, a signal is directed to a recorder or transmitter. In the "audition" position, a signal can be previewed off-air. For example, a DJ may play a CD through channel 3 in the "program" position (in other words, on the air) while at the same time previewing another disc or tape through channel 4 in the "audition" position. The "auxiliary" (aux) or "utility" (utl) are often used in production, such as to send signals to another studio.

Volume Control and Monitoring

  The volume or gain control is called a slider or fader. Such controls are variable resistors-much like water faucets in function. Raising the fader (pushing it away from you) increases the volume. Some older boards have rotary knobs called potentiometers ("pots") which fill the same function. Faders are easier to work with, as they provide a quick visual check of which channels are in use and at what level.

     One way to judge volume is simply to listen, but this is a relative measure, and what one operator deems loud may seem quieter to another. To more objectively indicate volume, control boards include a volume unit indicator (VU meter). Most use a moving needle on a graduated scale, ideally registering between 80 and 100  percent. Above 100  percent the signal is peaking "in the red" (because that portion of the VU meter scale is usually indicated by a red line) and may distort. On the other hand, a signal consistently below 20 percent­ and thus too quiet-is said to be "in the mud." Most newer boards offer VU meters with digital lights (LEDs) to indicate volume.

     Sound can be monitored in different ways as it passes through a control board. A common mistake is to run studio monitors quite loud and think all is well, when in reality the program signal going through the audio board may be at too low a level. Most boards also have provision for monitoring their output through headphones. When microphones are on ("live"), monitor speakers in the same control or studio space are automatically muted to avoid feedback howls or squeals.

     Another way to monitor (and preview) a sound source is to use a board's "cue" function, which allows any input to be previewed. Shifting a volume control into the cue position, usually marked on the face of the console, routes the audio signal to a cue speaker rather than on the air.

     Many control boards have additional features which make them more flexible. For example, some boards will automatically 'run a channel on when its fader is moved upward. Others include built-in clocks and timers. Many boards have simple equalizer (EQ) controls that increase or decrease certain frequencies, thus altering the sound of the voice or music by changing the tonal quality. These most often affect a range of frequencies-high, midrange, and low.

Digital Future

     Like other radio equipment, the control board is rapidly progressing from analog to digital mode. Incoming audio signals, if not already digital, are converted, and they remain in digital form while being manipulated through the mixer and ultimately output. Such digital boards begin to add new features and capabilities, such as hard disk audio storage. The most striking feature of the digital board is often the addition of an LCD display screen that provides status information for each channel.

     Although a digital board offers all the traditional functions of an analog board, it is usually more flexible. For example, instead of just two inputs per channel, a digital board may allow any channel to be assigned to any input. Such user­-defined functions allow a board to be custom-designed for a particular use. Another form of digital control board is the virtual audio console. Instead of a physical piece of equipment in the studio, an operator manipulates an image of a control board on a computer screen. A virtual fader or other console control can be managed with simple point-and-click or drag­ -and-drop mouse commands.

     Whether digital or analog, any control board is part mechanical contrivance and part creative component. While learning its technical operation is fairly easily accomplished, effective utilization of a board takes time and experience.