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	WPI Technical Theatre Handbook: Noise Gates
	Noise Gates Often equipment produces undesirable noise, or microphones pick up unwanted background noise. For instance, inexpensive computer sound cards emit a lot of hiss that is very noticable when the sound system is otherwise quiet. Also, microphones may pick up background noise that could prove to be distracting when played through a large sound system. These problems can be mostly eliminated by using devices known as noise gates. A noise gate will not pass an audio signal through it unless it is above the threshold level, set by a knob on the front of the unit. Once the sound level rises above the level set by the threshold knob, the gate opens, allowing the input signal to pass through it. Additional controls adjust how quickly the gate opens and closes. Some gates do not actually shut off the sound, but they reduce it by some amount. These gates have an additional control to adjust how much reduction is used when the gate is closed. Generally, a noise gate is inserted into a problem channel and adjusted such that the threshold level is set to be above the background noise. The end result is silence from the channel when there is just background noise from the input, and the normal signal when a level higher than the threshold is present. 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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