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	WPI Technical Theatre Handbook: Converting Sound to Electricity
	Converting Sound to Electricity Dynamic microphones are among the simplest types of microphones. They consist of a diaphragm that is attached to a small coil of wire. This coil of wire is mounted such that it is surrounded by a magnet. The diaphragm is arranged such that it will move when it is exposed to sound pressure. This, in turn, moves the coil, creating an electric current in it, due to the magnet. The current produced is an electrical representation of the sound that moved the diaphragm. Dynamic microphones are durable, reasonably inexpensive, and usually have good sonic characteristics. Their applications in theatre are numerous; everything from wireless mic transmitters to intercom systems can use dynamic microphones. They are also especially useful in situations where a production calls for an actor's ``disembodied'' voice to play a role, as dynamic mics are an excellent choice for speech and singing. Two common, favorable types of dynamic microphones are Shure models SM-57 and SM-58. These durable mics are suited to a wide variety of tasks, and are quite affordable. The microphone resting on top of the case in figure 6.2 is a Shure SM-58, while the microphone directly below that is an SM-57. Figure 6.2: A variety of microphones in a microphone road case. Condenser microphones and electret condenser microphones vary in design considerably from dynamic microphones. A full dissertation on the operating characteristics of condenser mics will not be given here; suffice it to say that they use properties of capacitance to produce a very small signal proportional to the sound wave entering the microphone. This signal is amplified with a small transistor amplifier mounted inside of the mic. Because of this, condenser microphones require some sort of power, either from a battery or what is known as phantom power (the powering of microphones remotely from the sound board). Condensers are very sensitive, and offer excellent sonic capabilities. For this reason, they can be useful in theatre applications where a sound needs to be picked up from some distance away from its source. A favorite condenser microphone for many applications is the Shure model SM-81. There are many other methods for converting sound energy to electrical engergy. Carbon, piezoelectric and ribbon are also common types of microphones, though less so than dynamic and condenser types. It is not within the scope of this book to provide an in-depth description of all types of microphones, so further reading elsewhere is recommended for those with an interest in the subject. Use of information in this document implies understanding and agreement with the copyright and terms of use. Specifically, no warranty is expressed or implied regarding the accuracy of the information contained within. YOU USE THIS INFORMATION AT YOUR OWN RISK. All trademarks are property of their respective owners. You must obtain permission from the author before using the contents of The Handbook for anything other than private use.	Table of Contents [Whole book in PDF 5.3MB] Contents Introduction Goals Sources Methods Conclusions Costumes Introduction Procurement Fabrics Color Patterns Fitting Rehearsal Clothing Design How to Begin Color Practicality Documents The Set Introduction Set Pieces Platforms Flats Stairs Rakes Other Structures Floor Coverings Construction Materials Tools Finishing Painting Types of Paint Mixing Paints Applying Paint Draperies Design How to Begin Documents Computer-Aided Design A Typical Set Construction at WPI Rigging Introduction Common Rigging Hardware Rope Wire Rope Thimbles, Wire Rope Clips, and Swages Shackles, Turnbuckles and Hooks Chain & Rapid Links Slings Fly Methods Non-Counterweighted Pulley Systems Counterweighted Fly Systems Lifts Chain Motors Flying Set Pieces Lighting Introduction Lighting Instruments Scoops Cyclorama Lights Parabolic Reflector Cans Fresnel Spotlights Ellipsoidal Reflector Spotlights Automated Instruments Color Color Theory Primary, Secondary and Complementary Colors of Light Light Mixing Practical Use of Color Glass, Gelatine and Plastics Dichroic Color Filters Patterns Dimmers Dimmer History Cables and Connectors Lighting Boards Control Design Washes Specials Cyclorama Lighting Color Lighting Angle Simulating Exteriors Lighting Design Paperwork Shop Order Instrument Plots Focus Sheets Computer-Aided Lighting Design A Typical Lighting Hang at WPI Audio Introduction Input Microphones Converting Sound to Electricity Directionality Analog Tape Digital Audio Tape (DAT) Compact Disc (CD) Mini-Disc (MD) Digital Samplers Computer Sound Cards Mixing Boards Signal Processing Equipment Equalizers Compressors and Limiters Noise Gates Effects Processors Output Power Amplifiers Speakers Crossovers Cabling and Connectors Line-Level Speaker-Level Automation Design Creating and Obtaining Effects Editing and Processing Effects Designing the Sound System The Input Section Signal Processing The Output Section A Typical Audio Setup at WPI Power Introduction Basic Theory Power Feeds Power Distribution Boxes Power Protection Important Considerations Special Effects Introduction Animated Costuming Smoke and Fog Pyrotechnics Acknowledgements References List of Figures Index About this document ...

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