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	WPI Technical Theatre Handbook: Compressors and Limiters
	Compressors and Limiters Quite frequently, microphones will be used in a theatre application. These mics may be on the actors, or elsewhere. One frustrating aspect of running sound for a show in cases like this is that often the volume level will not be loud enough at times and too loud at other times. This can be due to many factors, most of which involve the actors. This problem can be practically eliminated through the use of a device called a compressor/limiter. A compressor/limiter reduces the dynamic range of an audio signal. Simply put, it makes quieter things louder, and louder things quieter. Several controls are available, such as attack and release times, threshold levels, and compression ratios. There are two main schools of setting compressor controls; one dictates that some calculations be made, while the other follows the ``fiddle with it until it sounds good'' methodology. The calculation scheme is rarely used when the compressor is being used on an input such as a microphone. Since compressors/limiters can be placed on the output stages of sound boards, they are often used to protect the speakers and amplifiers from excessive peaks. Setting the compressor such that the sound may not rise above a certain level is fairly easy, and in this sense the compressor is merely acting as a limiter. However, finding the level that won't destroy the speakers isn't necessarily easy, as there are many factors to consider. This is where the calculations can come in. Needless to say, they are beyond the scope of this book. Consult the Yamaha Sound Reinforcement Handbook or a competent audio engineer for more details. The best way to get a feel for how a compressor works is to hook one up and insert it on a microphone input on a sound board. Adjust the attack, release, threshold and ratio until the sound seems fairly natural. Try moving the microphone closer and farther away while speaking into it. With appropriate settings, the ill-effects of an person speaking quietly at one moment and yelling the next, or moving closer and farther away from the microphone can be reduced. 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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