Digital @ The Arts Unit Creative Classes

Audio fundamentals – processing devices

Learn the fundamental elements of a basic audio system

Student VET entertainment, music and drama resource developed by The Arts Unit

Years 9 to 12 music and drama, Years 11 and 12 VET entertainment

What will I learn?

You will:

  • identify the basic principles of an audio system

  • discover how to use an audio mixing desk.

Schools Spectacular (Photo credit: Anna Warr)

Audio desk

An audio mixer takes several inputs, then mixes or manipulates the audio before sending it to the outputs.

Watch the 2 videos:

  1. 'How to use a mixing desk' with Mark Zovaro from The Arts Unit to learn about the input section on an analogue audio desk

  2. 'How to mix live music faders and groups' on the output section on a digital desk.

2. How to mix live music – faders and groups

Duration: 10:29
Audio desk channel

Tasks

Draw the audio desk channel strip and label each section or dial.

Answer the following questions:

  • What sources do you use in each mic, line and insert input?

  • What is PHANTOM POWER?

  • What can occur if there is too much PRE-AMP or GAIN?

  • What is HPF and why is it used?

  • What HERTZ range does the human ear have?

  • What is the purpose of the EQUALISER section?

  • How do you use the EQUALISER section in a performance?

  • Explain the analogy used to define the AUXILIARY sends.

  • What is the difference between post and pre-AUXILIARY sends?

  • What is the PAN dial used for?

  • When is the MUTE button useful?

  • What is PFL and how is it used in a performance?

  • What does the red LED light indicate if it lights up and what would you do if it does?

  • When using the fader, what dB region should you be operating in during a performance?

  • What is the key to a good mix?

  • What is the purpose of group faders and when could you use this?

  • What differences did you see between the analogue and digital audio desks in the videos?

Practical task

Set up your basic audio PA system and take yourself down the input channel to adjust your dials. Experiment with different sound sources to learn how the sound changes.

Analogue and digital mixing desks

Watch the video 'Digital mixer vs analogue mixer' to see the differences between each of these mixing desks, how they are used, as well as the benefits and limitations of each.

Digital mixer vs analogue mixer

Duration: 09:13

What is feedback?

Audio or acoustic feedback can occur for many reasons throughout a performance.

Feedback can be in the form of a hum or buzz sound coming from the speakers or a high pitch squeal sound that can be painful to the human ear.

Immediate feedback from an audio system can be minimised by reducing the gain or pre-amp from the specific input channel creating the feedback. The LED lights can often identify this channel by the increased signal highlighted in the red zone.

The way you set up your audio PA system and the placement of equipment can also reduce the possibility of feedback.

Watch the video 'How to prevent feedback on stage' to see how to prevent audio feedback.

How to prevent feedback on stage

Duration: 01:58

Practical task

Using the equipment you have, create feedback by increasing the gain on a channel or placing a microphone in front of a speaker and practise eliminating this feedback.

Graphic equaliser

Equalisers are used to shape the tone of a sound. They are a helpful tool in eliminating ‘feedback’ problems. In addition to eliminating feedback, overall sound system equalization is used to adjust the system such that it sounds pleasing.

Watch the video to see how equalisation is applied to sound.

EQ Explained

Duration: 05:21

Graphic equalisers consist of a set of slider controls and circuitry that allow boosting or cutting of a range of frequencies. Each slider is set to control a small range of frequencies, and can usually boost or cut this range fairly substantially.

Watch the video to see how a graphic equaliser is used.

How I set my graphic EQ

Duration: 10:03

Practical tasks

  • Connect the speaker to a microphone and adjust the high, mid and low frequencies on your audio mixing desk and listen to how your voice changes as you boost or cut each frequency.

  • Play an audio track and adjust each frequency on a graphic equaliser and listen to the changes you hear in the track.

  • Watch the video on how to equalise the room. Use this same technique to equalise your space with a graphic equaliser.

How to Equalize – EQ a Live Sound System – How to Ring out Speakers for Feedback

Duration: 06:55

Effects

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.

Watch the 3 videos and listen to how the audio effects are applied.


1. What are audio effects?

Duration: 03:18

2. Reverb and delay explained

Duration: 06:29

3. Reverb examples

Duration: 01:11

Practical tasks

  • Using a sound source, either a microphone and a guitar through a DI Box, add effects to the audio as someone else uses it and listen to how it changes the sound of either a voice or an instrument.

  • Identify examples of when you could use effects effectively in your context.

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