Download Electricity and Sound

Electricity and Sound
Transducers
Audio Signals
Cables and Shielding
Sound Environments
Physical and Virtual - Working Definitions
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Physical = Sound we hear
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Physical environment of the audience / performers.
World of physics and acoustics
Virtual (electronic) = Audio Systems
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Electrical signals that are representations or facsimiles of
sounds
Technical Environment of equipment, wires and “techie”
Sound Environments
Physical and Virtual - Working Definitions
Transducers - Link Sound and Audio Environments
Equipment System
Microphone
Virtual Environment
Speaker
Audio
Performers
Physical Environment
Sound
Simple System Block Diagram
Audience/Performed
Sound Environments
Physical and Virtual - Working Definitions
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Worlds meet at “transducers”
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Transducers are devices that convert energy from one
form to another.
In the theatre:
 Convert sound to electrical signals. • Microphones
 Convert electrical signals to sound. • Speakers
Sound Environments
Physical and Virtual - Working Definitions
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Every time a transducer is used, some
information is lost
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No transducers are 100% efficient.
The sound represented will change
Clipping will occur
Audio Signals
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Microphone level
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Typically around 2mV
The signal created by a microphone and other low power input devices
Typically uses XLR connectors or ¼” RTS (ring-tip-sleeve)
Line level
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Standard voltage for signals between pieces of equipment
Ranges between .316V and 1.23V
The audio signal from CD players, DAT decks, MD players, mixers
Typically uses
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1/8” or 1/4” phone plug or TS (Tip-Sleeve)
RCA (cinch)
Speaker level
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Much higher voltages depending upon the power ratings of the amplifier and load
The signal from power amplifiers to loudspeakers
Typically uses
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Speakon connectors
Twist lock
Bare wires
Audio Signals
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Impedance (Z) matching
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When interconnecting equipment it is important to match
levels
 Sending a line level signal into an input which is expecting a
microphone level signal will cause distortion
High impedance (High Z)
 Generally line level signals on unbalanced lines
 Line outs from audio equipment
 Outputs from electronic instruments
 Outputs from mixing desks
Low impendence (low Z)
 Generally microphone level signals on balanced lines
 Outputs from microphones or Direct Injection Boxes
Audio Signals
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Direct Injection Box
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Used to convert an unbalanced Hi-Z speaker or
instrument level output to a balanced lo-Z mic
level output
Usually used to enable an electronic instrument to
be delivered long distances on lo-Z lines to
minimize noise
For next class
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Read
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P. 28-38, Leonard
Learning Basic Soldering handout