Mixer

.There are generally 2 types of mixer - for sound reinforcement and for recording.  Recording mixer has an additional tape return stage for signal to pass through before going to monitor.

The console is basically a collection of channels. Each channel has a certain arrangement of processes that lead down to the fader or volume knob:

(1) Gain (a.k.a trim or attenuation) adjusts the incoming signal to the console

(2) Auxiliary is used to route signal to an external device (to modify or add to the signal) and route it back to the desk to continue down the channel.

Effects:
Delay - repeat of a single source signal produced.  The distance between the original sound and the delay can varies from minimum 10-20 msec to maximum 240-250 msec.  Delay can improve a vocal line to create an illusion of a very large room.

Echo - what you hear in very large spaces with reflective wall.  It is decaying repeat of an entire sound signal.

Reverb - a series of echoes that overlap.  The overlapping of signals creates a cpntinuous sound that eventually decays to zero  Reverb is used often to sweeten up a dialigue track or to create the impression that the sound is in an acoustically reverberabt room.  Concert hall usually have a decay of about 1.5 to 2.5 seconds long. Smaller hall features 1 to 1.5 seconds reverb times.

Chorus - takes the original signal and slightly delays it.  All of this is heard at the same time, giving a very solid thick sound.  This is like simulating a group of performer singing together, slightly out of sync.

Pitch shifting/bending - increase or decrease the frequency

(3) Equalization basically divided into low, medium and high frequencies covering the audible range of human hearing.

(4) Fader is the last stage.  Once the signal completed its path to the bottom of the channel, it reaches the fader or volume knob.  The input signal is once again adjusted.  The signal is usually bussed to the submix section of the console.  This si another group of faders where all of the signals are collected from all active channels.  These are usually called busses.