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STM4006- Intro to Sound and SFX

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by

Al McNichol

on 22 November 2017

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Transcript of STM4006- Intro to Sound and SFX

Objectives Today
1. Understand fundamentals of a basic sound system;
2. Show competency in connecting and setting up a basic sound system;
3. Be able to source appropriate sound effects relative to a given script;
4. Show competency in using audio playback hardware and software.
Today's Schedule
.....is in two parts
PART 1 Sound System Setup
10:30-11:00 getting to know the fundamental equipment.
11:00-12:00 setting up a system and calibrating audio signals.
PART 2 Audio Playback Control
12:00-12:30 sourcing sound effects and learning about soundfiles.
12:30-13:30 learning to use audio playback hardware and software.
Sound System Setup
Sound Effects (SFX)
and Audio Playback Control

What is a sound system?
a system to amplify sound by converting it into electrical energy, increasing the power of the electrical energy, and then converting the more powerful electrical energy back into sound.
....a basic sound system?
purpose being......
to allow a quieter sound to be heard and understood within the audience arena.
INPUTS
PROCESSORS
OUTPUTS
microphones
(transducers)
mixing desks
signal processors
amplifiers
speakers
mic level
line level
speaker level
Devices
Signal Levels
(very low)
(low)
(med-high)
Connectors
input or output?
3-pin XLR
male
female
needs a pre-amp
1/4" (6.35mm) TRS
1/4" (6.35mm) TS
1/8" (3.5mm) TRS
RCA phono
SpeakON®
Cables
Audio signals
Audio signals are electrical energy initially resulting from:
input transducers
signal processors
output transducers
All these devices have either
inputs,

outputs or both
.
balanced or unbalanced?
sound
wave
sound
wave
Balanced V Unbalanced
These are terms used to describe the I/O
connections

of audio devices.

What is the basic difference?
uses
3
connections to carry the signal.
hot, cold, ground
uses
2
connections to carry the signal.
hot, ground
...main purpose?
eliminate electrical noise
How does it work?
Unbalanced
A device with an unbalanced output produces a voltage between a single “hot” output connection and the circuit’s signal common point, which is usually connected to the equipment’s chassis. The common term for this is “ground,” though it’s not necessarily electrically connected to the actual ground itself.

A device with an unbalanced input receives its input voltage between a single “hot” input connection and ground.
How does it work?
Balanced
A device with a balanced output produces a voltage between a “hot” and "cold" output connection and the circuit’s signal common point, which is usually connected to the equipment’s chassis. The common term for this is “ground,” though it’s not necessarily electrically connected to the actual ground itself.

A device with a balanced input receives its input voltage between a “hot” and "cold" input connection and ground.
The "hot" and "cold" conductors carry the signal 180˚ out of phase. Any electrical noise interference 'jumps' on the signal....in phase. At the input stage, both signals are flipped back in phase. This cancels out the noise as it is now 180˚out of phase.
Noise cancellation
Diagram showing how noise is cancelled on a balanced connection.
Transmitting device
Receiving device
connection
|
|
wiring>>
TRS - XLR wiring terminals
XLRf
TRS
XLRm
Key
Unbalanced Cable
Unbalanced connections
single conductor (centre)
braided 'shield'
= 'hot' signal
= ground, return signal path
Coaxial cable (coax)
cable runs:
less than 40m with line level signals
5m with instrument level signals
Microphone Cable
Balanced connections
2 conductors, twisted (centre)
braided 'shield'
= 'hot' 'cold' signals
= ground, no signal
Microphone/balanced cable
cable runs:
c. 75m
(to reduce interference)
can be greater with good quality cable
Caution!
Treat all cables with the utmost care.
Coil them carefully (insert a twist each coil).
Test them regularly.
Buy the best quality ones you can afford.
Cable etiquette.
Good quality cable =
Good quality connectors =
We do not want to see this..
Classifications of audio signals
mic level signals (low level)
There are a number of different signal levels in audio circuitry. The four most common for audio engineers are:
instrument level (low level)
line level (medium level)
speaker level (high level)
= post preamp
= requires preamplifier
= post amplifier
blurb>>
Inputs (preamplifier)
Mic level
is the lowest, or weakest, level signal of the four and requires a preamplifier to bring it up to Line level.

Instrument level
signals live between mic and line level signals and have the most variation. You typically see this kind of signal come from an electric guitar or bass. They also require a preamplifier to come up to line level.



Signal Processors
Line level
signals are the highest level signals before amplification. This is the type of signal that typically flows through your recording system after the preamplifier stage and before the amplifier that powers your speakers. There are two types: Consumer and Professional. Consumer line level is rated around -10dBV and is what you’ll find in products like a CD player. Professional line level is rated around +4 dBu and is found in things like mixing desks and signal processing equipment. If you see that little switch on your gear that says +4 or -10, that’s what that’s for. Be careful not to send a line level signal to a preamplifier expecting a mic or instrument level signal.




Output (post amplifier)
Speaker level
signals are post amplification. After a line level signal enters an amplifier, speaker level signals are output to your speakers. These signals are much higher in voltage than line level and require speaker cables for safe signal transfer. You should never plug a speaker level signal into a source expecting anything less than a speaker level signal.

Cable wiring diagrams
XLRm-XLRf
XLRm-1/4" TRS
1/4"TS-1/4" TS
1/4"TRS-1/4" TRS
others>>
1/4"TRS-RCA phono (mono)
1/4"TRS-1/4"TS (insert lead, stereo -2xmono)
Loudspeaker Cables
Loudspeaker cables are typically 2xcore conductor wires, unshielded. They are not the same as unbalanced instrument/line level cables. Even though sometimes 1/4" TS connectors appear on loudspeakers as connectors.

They are dedicated loudspeaker cables.
Loudspeaker Cables
However, they can be larger diameter conductors and carry more signals. This depends on the wiring configuration of the speaker system.
Heavy Duty
These will be found on some more complex speaker system arrays
EP5 -5pin
examples of devices
Single core audio cable
Speakon® Wiring Configurations
NL2-NL2
NL4-NL4
NL2-1/4"TS
(Boyce, 2014, p.113)
(Boyce, 2014, pp.108-112)
Hot (+)
Cold (-)
Shield
( )
What does a DI Box do?
http://www.dawsons.co.uk/blog/why-use-a-di-box
(Direct Injection)
coverage
quality
loudness
extra stuff......
By the end of today's session you should:
wiring>>
Soundcraft GB2 24/4/2 mixer
https://www.soundcraft.com/products/gb2
Soundfiles
Sound effects are typically a 'soundfile'
Audio that has been 'digitised' and stored in a file format.
100s of types developed over the years
Most common file formats are:
.wav
.mp3
Full quality
Compressed
Categorising SFX
Video Tutorials
https://www.youtube.com/playlist?list=PL4CF0FA9E71C443FE
... a broad selection exist in Apple OSX System under 'Apple Loops'
categories for SFX:
Atmospheres
Spot FX
Music
create an overall mood/scene
spot sounds to enhance the scene/setting...add realism
soundtrack to enhance the mood/action
Planning SFX
1. interpret the script and identify SFX required
what is a soundfile?
.caf
Core Audio Format (Apple)
2. Source the sounds required
Experiment with Sound
play....have fun!
think creatively
less is more.....
Playback
image in my head......?
what is in yours?
Qlab 4
combines cue control for show control of sound light and video
http://figure53.com/docs/qlab/v4/
...manuals and 'Getting Started'
Practical Demo
Practical Activity (20mins)
1. Interpret your own script to identify basic sounds required
2. Load the basic sounds into Qlab to preview.
3. Input laptop audio into PA system and evaluate the sounds.
...in pairs
Summary
1. Understand fundamentals of a basic sound system;
2. Show competency in connecting and setting up a basic sound system;
3. Be able to source appropriate sound effects relative to a given script;
4. Show competency in using audio playback hardware and software.
By the end of today's session you should:
Introduction to Sound and Sound Effects
STM4006 Backstage Technical Skills
Full transcript