One role of a mixing board is to accept input from different audio sources. This input is received by a number of identical vertical control arrangements known as channel strips. Inputs to the board come from sources such as synthesizers, microphones, computer audio interfaces and sometimes even CD players. While the layout of the input sections of mixing boards may differ, they all have the same basic function.
Another role of a mixing board is to control mixed output signals. Outputs are typically connected to effects devices which route signals from the effects sends (may also be called "aux sends"). The strength of the signal can be varied by adjusting the effects sends knobs. For any signal to be sent, the effects sends master must be turned on. There are faders for each of the eight group outputs (or buses) in the output section. To determine whether the signal a channel sends will be altered, adjust the pre- and post-fader buttons. While the pre-fader is used to hear an altered sound and fade out the original signal, the post-fader affects the overall strength of the signal sent, fading out both the original and the altered sound.
Auxiliary routing is the process by which signals are transferred between the channels of a mixing board or from the mixing board to and from an external device. The panoramic potentiometer manages the odd and even or left and right balance of a channel's output. If the input level becomes too high, the red overload light indicates input distortion. While the solo button isolates sounds for tasks such as equalization, effect return verification and missing signal identification, the mute button silences the channels when necessary.
In addition to the controls necessary for its three main functions, the mixing board also typically features other useful controls. The gain, or trim, control is located near the top of a mixing board and controls volume. In the monitor section, the talkback circuit allows for communication with singers in the studio or conductors on stage. Some mixing boards may also include a rumble or high-pass button to minimize unwanted low frequencies that result from mic stand vibrations or foot tapping.