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	WPI Technical Theatre Handbook: Control
	Control Since modern lighting setups have separate dimmers and boards which are often located a hundred or more feet apart, a method of control must be used so that the board may control the dimmers. One of the first methods used to accomplish this task was a purely analog scheme. Individual wires for each channel are used, with each carrying a small (typically zero to ten volt) analog signal representative of the position of the fader on the board. This method works reasonably well, and is in fact still used in many theatre installations. However, the multi-conductor cabling is expensive, difficult to maintain, and quite bulky. The amount of cabling required to run a large number of dimmer channels can become difficult to manage after a time. To combat these problems, several different schemes have been developed over the years. Most rely on some form of multiplexing, the combining of several discrete signals into one by dividing time up into several slices and devoting a slice to each signal. This allows all of the multiconductor cabling to be replaced with a single piece of cable, using typically only three conductors. Several schemes for multiplexing lighting information have been developed. Two of the most common ones AMX192 (analog multiplex, 192 channels) and DMX512 (digital multiplex, 512 channels). DMX512 is what is used at WPI for lighting control. DMX512 can be run using regular 3-pin microphone cable over long distances. This affords much flexibility in the placement of the lighting board and dimmer racks, as they can be spaced quite far apart. Most new dimmers decode DMX512 internally. The NSI dimmers that WPI owns are prime examples of this. However, the majority of the dimmers used at WPI are older analog models that have been retrofitted through the use of DMX512 demultiplexers. These devices decode the digital signals used on a DMX line and convert them to analog signals used by the dimmers. Devices such as this give older devices an extended life, as they can be controlled by the latest computer lighting boards. Figure 5.21 shows one such demultiplexer. Figure 5.21: DMX512/AMX192 demultiplexer, used to convert DMX or AMX signals to 0-10V analog signals used on older dimmers. The three main dimmer racks used at WPI employ DMX demultiplexers manufactured by Electronic Theatre Controls, Inc. DMX512 is also used for the control of many automated lights. The High End TrackSpots used at WPI are controlled over DMX. Individual channels of DMX are assigned to functions such as pan, tilt and color. Appendix Q has more information about the DMX channel mapping used on the TrackSpots. 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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