Gain adjusts the sensitivity of the input. You may have to contend with a singer with a loud voice who holds the mic up against the mouth and another with a quiet voice who holds the mic a foot or more away both at the same time. The gain control will enable you to bring the input levels closer together. Some mixers have an additional control (a "pad") which automatically cuts the input by 12dB or so when the channel begins to overload. It is mportant to remember that gain structure is NOT volume control.

Generally, each channel has some form of equalisation (EQ), which are controls to adjust the tonal quality of the sound. Small mixers may only have adjustments for bass and treble, while larger boards may provide bass, treble, mid-range, and adjustable range controls. This adjustable range control is called parametric equalisers and allows the user to choose not only to boost or cut a frequency range, but also to choose which range to work with. Equaliser controls function much like the familiar bass and treble knobs found on stereos. It is common to use an equaliser to improve or alter the sound of an input. For instance, removing bass from wireless body microphone inputs can reduce annoying ‘clunking’ sounds that may be picked up from the microphone.

A graphic equalizer offers gain control of a fixed set of frequencies, usually the ISO third-octave frequencies. A parametric equalizer offers gain control over any frequency within a range and also allows users to control the bandwidth or Q of each filter. 

You may want to add echo or reverberation (or any one of a number of other possible effects) to the incoming signal. Some mixers can do this themselves, but with the majority you need to use an external signal processor.  The auxiliary sends allow this: with them you can control the amount of signal to be sent from the mixer to the processor.  Most mixers have at least two auxiliary sends: the better ones have four.

An audio effects processor takes an audio signal and manipulates the sound to create a different effect.

This should not be confused with creating actual sound effects (known as Foley sound effects) such as a doorbell, telephone, or door slam.

Many mixing consoles have the basic effects built in. There is also what is known as an ‘effects rack’. This is a separate device that contains a wide range of effects and would become a component of an audio system.

Two common effects are delay and reverb.

Pan places the sound in a stereo image.  By turning it fully to the left, you send all of the signal to the left output channel only, and by turning it fully to the right, you send it all to the right channel.  By turning it half to the right, you send two-thirds of the signal to the right and and one third to the left, and so on. You can use this in the front of house speakers to create a certain effect for the audience.

The fader is the volume control for the channel.  By adjusting the levels of the faders, you alter the balance of the output sound.  Thus, for instance, you can make a singer louder than his backing, or further balance the two singers we mentioned above.

The LED lights will usually work something like this. The bottom light will light up when a weak signal is sent through the board at low volumes and as the volume (intensity of the output signal) increases, the next light above it will light up, and as it increases even more, the next one above it will light up, and so on, and so on. These lights are usually either green or orange or yellow or red. On my mixing board, the red lights are near the top and are indicators that you are near maximum allowable output signal. 

In groups of 2 or 3, use PowerPoint (or similar app/program) to create a presentation that would help explain each of the functions within the channel strip of a mixer to a teenager new to Entertainment.

Digital mixers use electronic sound transmission to operate.  They are expandable, so you can connect a greater number of external devices than you can with the same size analogue console.

A big advantage is that you can pre-program a controls ahead of time and bring them up when needed.  Single controls can have multiple functions.  This enables you to have a smaller mixer with greater functionality.

Digital mixers come with a large amount of on onboard processing equipment, often having a Graphic EQ (Equaliser), Parametric EQ, Sweepable EQ, Notch EQ and Shelving EQ.  Plus, large libraries of editable audio effects such as reverb, delay, pitch shifting, chorus etc.

It can be more economically feasible to purchase a digital console due to the large variety of onboard effects and controls that come standard with the console.

One of the biggest advantages of a digital mixer is that ‘scenes’ can be set up and saved during rehearsals.  This includes the fader levels for each input, the individual channel EQs for each channel, Effects used for each channel and the overall EQ for the item.  All these adjustments done and controlled by one button.

Moving fader automation is a system thay employs motorised faders in addition to or instead of traditional faders. Automation allows an engineer to record date about fader moves that can be repeated during every playback without the engineer having to manually move the controls each time. Adjustments over mutiple faders can then be done with relative ease.

Activity

We have an audio desk that has automation in addition to being able to move the faders manually. You will now have time to use this desk and discover its capabilities.

Watch the video (left) to get a good overview of how to mix live audio.