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Electricity and Sound. Transducers Audio Signals Cables and Shielding. Sound Environments Physical and Virtual - Working Definitions. Physical = Sound we hear Physical environment of the audience / performers. World of physics and acoustics Virtual (electronic) = Audio Systems
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Electricity and Sound Transducers Audio Signals Cables and Shielding
Sound EnvironmentsPhysical and Virtual - Working Definitions • Physical = Sound we hear • Physical environment of the audience / performers. • World of physics and acoustics • Virtual (electronic) = Audio Systems • Electrical signals that are representations or facsimiles of sounds • Technical Environment of equipment, wires and “techie”
Sound EnvironmentsPhysical and Virtual - Working Definitions Transducers - Link Sound and Audio Environments Equipment System Virtual Environment Audio Speaker Microphone Performers Physical Environment Sound Audience/Performed Simple System Block Diagram
Sound EnvironmentsPhysical and Virtual - Working Definitions • Worlds meet at “transducers” • Transducers are devices that convert energy from one form to another. • In the theatre: • Convert sound to electrical signals. • Convert electrical signals to sound. • Microphones • Speakers
Sound EnvironmentsPhysical and Virtual - Working Definitions • Every time a transducer is used, some information is lost • No transducers are 100% efficient. • The sound represented will change • Clipping will occur
Audio Signals • Microphone level • 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 • 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 • 1/8” or 1/4” phone plug or TS (Tip-Sleeve) • RCA (cinch) • Speaker level • Much higher voltages depending upon the power ratings of the amplifier and load • The signal from power amplifiers to loudspeakers • Typically uses • Speakon connectors • Twist lock • Bare wires
Audio Signals • Impedance (Z) matching • 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 • Direct Injection Box • 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 • Read • P. 28-38, Leonard • Learning Basic Soldering handout