Glossary of Terms



abseil - A European mountain climbing term which refers to a long fast fall taken with the assistance of a rope and a harness. The climber fastens himself to the rope with a friction device. This simple device controls friction on the rope and, thus, the speed of the fall.

AC - Alternating current. This is the sort of electric power delivered to our homes and businesses in America. It is so named because it changes polarity (positive becomes negative and vice versa) 120 times a second. This is also known as "60 cycle AC". Power is often referred to as AC around a stage because of the frequent presence of DC ("direct current" - no polarity change) in many equipment circuits.

adaptofier - A mongrel designation.  It is a slang reference to a device which adapts one style of connector to another style.

Avo - In general, Avo Lites Ltd., a British manufacturer of lights dimming and control equipment. In this journal, it refers exclusively to the 90 channel console which controlled the conventional lamps.

backline - Traditionally, the line of amplifiers behind the band on a rock and roll stage.  Normally, drums are a part of this line. The term is virtually archaic, with the advent of custom staging layouts. These days, band gear is less commonly staged in layouts which conform to such straight lines. It is often staged to afford performers a much more interesting space to play in, with risers of different 3D levels and 2D depths on the stage plan. However, the term still has one significant use: the technicians who care for amplifiers, keyboards, & drums are referred to as "backliners".

black box - In proscenium theater, this is the space in which the action of the play is to take place. The space is defined with the aid of heavy black curtains. The object is complete control of all lighting within the play space; whatever is not in light, is in black.

booms - These are vertical pipes. Lights are hung on them to give horizontal (or nearly so) angles on the stage, most often from the side, sometimes from the front.

bridle - A rigging technique which was originally designed to spread the load of a hung object over two or more beams. However, in rock touring, it is sometimes necessary to "create" a point in mid-air where there is no beam directly above the object to be lifted. This is described in greater detail in Houston.

channel - The most primitive unit of lighting or sound control. Channels can be grouped together in order to control many selected channels with a single master.

chase - In lighting, an automatic sequence of switched channels. The chase is programmed before the show, and set in motion on cue.  Modern digital consoles can perform chases involving aspects of control including timed fade, color changer control, intensity, focus of automated instruments, and many other complex functions.

Color Rams - Manufactured by Weyburn Inc. The Color-Ram has emerged as the most effective device for changing color in a conventional lamp.  It consists of a specially prepared roll of gels, which is precisely scrolled in front of the instrument by digital stepper motors. It communicates with a control computer by means of the DMX 512 digital protocol, which is in wide use throughout the industry. The Color-Ram is very fast, precise, quiet, and reliable.

color changer - Any device which changes the color of a conventional instrument. The general form is a scroll of gels which is rolled, under control, in front of the instrument. It is housed in a frame which fits in the instrument in place of the normal, static, gel-frame. In this journal, the term will refer to the Color-Rams, generally.

connector - Any device which connects a line or cable to any other similar device in a circuit.  A common example is the parallel blade or "Edison" connector. This is the connector found on almost every household appliance.  Connectors differ with their application and load. For instance, the Edison connector is designed to carry 110 volts AC. One blade carries the neutral line of the AC circuit, the other carries the 110 volt "hot" line.

On a stage, we use a staggering variety of connectors to deliver every conceivable sort of power and signal. Some deliver very small voltages which carry microphone signals. Others carry very high voltages and amperages in complex combinations. A heavy duty connector delivering power for chain hoists, for example, can have 5 pins: 3 deliver 110 volts each, a neutral pin, and a ground pin.

A bit of fun: Try wandering up to a busy sound guy and telling him that you need a special adapter. Tell him you need to get from stereo RCA to Cam-Lok. (RCA is the sort of connector found in many home-stereo applications; Cam-Lok connectors are used in heavy-duty AC delivery.)  The applications of these two devices are worlds apart, and the request will undoubtedly stop him dead in his tracks.

A tip o' the hat to Jim "Jid" O'Brian (Rock & Road Audio) for this little tweak.

conventional lamps - Any of the more traditional theatrical instruments which do not move, change color, or perform any other robotic function.  They must be focused prior to performance.  Typically, they only respond to one sort of control: dimming. They can often be mounted with color changing gear, but color changers are considered as separate from the instrument, in reference and for purposes of control.

cue - A specific moment in any show which calls for a specific production act, whether by the performers or technicians. In lights, the term refers to a specific "look" which has been designed for execution at one of these moments.  Can also refer to audio presets, rigging actions, performer entrances, etc.

DAT - Digital Audio Tape.  An extremely high fidelity audio source.

deadhang - Any rigged point which falls directly under a beam. 

deck - In staging, the principal platform from which all of the rest of the production rises.  In arena applications, it differs from the floor: the deck is built on the floor.

dim - (verb) The act of controlling a dimmer. A lamp can be dimmed up as well as down. Thus, it is just as correct to say, "Dim it up", as to say, "Dim it down". 

dimmer beach - A slang reference to the area including and surrounding lighting dimmers. I first heard it in 1984 (Huey Lewis - Morpheus Lights).  It has since become almost universal in the business. Research attributes the origin of the term to the famous production manager of Red Rocks (Denver), Jimmy Lewis.

EQ - "Equalizer" or "equalization".  The first term refers to the electronic device audio technicians use to cut or boost certain frequencies which make up a given sound. A given sound which can be objectively identified according to component frequencies will often sound different to the ear, in different rooms.  This is because each room has its own unique characteristics of absorption and reflectivity: some frequencies are reflected, others are absorbed. Every room has it own special response.

Equalization is used to reinforce those frequencies which are absorbed, and to diminish those which may be overly active due to conditions of reflectivity. This process is roughly analogous to dimming a light or, more  accurately, coloring a light with a filter to remove certain frequencies of light radiation.

The set of frequencies and levels desired or arrived at (sometimes the two are very different!) is known as an "eq" (noun). The verb (to "eq") refers to the act of equalizing. 

This can be a tortuous affair to lights guys. It often involves signals of a precisely known type ("white noise" or "pink noise", depending on the  engineer and his preferences) blasting through the house at extremely high volume. The engineer uses RTA ("real time analysis") techniques to view, graphically, the response of the room to his signal. He then tweaks the eq  for optimum performance.

Normally, this happens just as lights guys are beginning their focus, a time when quiet for purposes of ground to truss communication is very  important. Every lights guy of any experience has waited helplessly on a truss, while trying to sign to a guy on the ground that he needs a new lamp or a meter, etc. Neither one can understand or hear the other, and both curse the audio guys. It's happening, right now, in an arena near you.

floor support - Refers, generally, to devices which lift trusses from the ground, contrasted with hanging them from overhead beams. Normally,  these are made by Genie Industries, and are known as Genie Lifts. They are very clumsy to work with, and I am never comfortable around them.  They take immense amounts of valuable floor space with wide outrigger legs which are perfect for banging one's shins on. However, when there is no other option for getting the trusses up (no rigging points - like D.C.),  nothing else does what they do.

fly rail - The backstage area of a proscenium theater where all objects flown on house rigging are controlled. All of the rigging lines run down one of the side walls. Their loads are balanced with counter-weights. This arrangement of lines and friction devices for control runs along the wall in a long rail, hence the name.

F.O.H. - Front Of House. The audience space of the theater. In general, a technical reference to f.o.h. will mean "the mix": the station where lighting and house audio are controlled or "mixed". However, sometimes the references are much more general. Someone who asks, "Have you seen Zoomer lately?", might be told, "Yeah. He was out front about ten minutes ago." The seeker then goes forth to f.o.h. The first point of the search is the mix. However, in the quoted reference, "out front" can mean anyplace from the ticket booth in the lobby to the spotlight booth at the top of the balcony.

The Seeker may never be seen or heard from again.

focus - (noun) The set position of a instrument in relation to its target; the direction it points in. Can also refer to the setting of a lens train in order to harden or soften the edge of the pool.

(verb)  The act of setting a focus.

gain structure - Roughly, the relationship of the strength of one audio signal (or set of signals) to another. These relationship sets are conceived of as an interdependent whole: one element of the set affects the others. Audio  engineers are the only ones on a stage who consider signals in this way.  Players, normally, don't think of anything but their own sound first. This is what causes audio guys to tear their hair out when somebody turns up: the precision of audio control and mixing degrades when the gain structure is violated.

It must be remembered that this is a lights guy's description. Any hum-heads who are laughing as they read this should understand that I write  this out of sympathy felt in watching them tear their hair out...I don't have to bother with it.

gobo - A thin metal plate which fits into an ellipsoidal spotlight. It is etched with a pattern, and when light is sent through the pattern, through a lens train, the pattern is then projected, in light, on a surface such as a curtain or set.

grid - The structure from which any rigging is suspended. May be made of wood or steel.  Usually a cross-hatch of beams which afford a multiplicity of hanging points.

ground - The line in any electrical circuit which carries stray voltage to ground (earth). It is very important in the event of disruption of a circuit: any voltage which contacts something which a person can touch will be guided safely home (to earth) before a shock can occur.

hand-grenade hour - This a very special moment.  It is that moment when one crawls into bed, very early in the morning. The sun is just beginning to come up, and one feels a slim chance of falling asleep for a few hours...until the birds begin to sing. At which point, one reaches into the night stand for one's hand grenade and, opening the window, pulls the pin...

hum-head - (affectionate diminutive)  "Sound guy".  It's a "them" & "us" sort of thing.  They call us "squints".

IATSE - International Alliance of Theater & Stage Electricians. The stage hands' union. Almost all cities in the United States which have a market for production services, also have I.A. union locals. They come in a wide variety of flavors, from very tasty to really yucky. When they are good, they are a joy which is unique to the structure of a union: the "brotherhood" is clearly observable as valuable to the effort.  They take pride in the ability of the  membership, and they demonstrate all the best qualities of authentic teamwork.

When they are bad, they are worse than inept.  They can be positively destructive.

instrument - Any device which is designed for the output of light. To refer to a "light" could cause confusion; "Whaddya mean, `light'? You mean the lamp (bulb) itself??" Many instruments, such as ellipsoidal spotlights, robotic instruments, etc., have many components.  When referring to the entire device, one often calls it an "instrument".

intro - Introduction. Often, introduction segments of a song are extremely important to getting the tone of the lights display off to a good start. If the first light to fall on the stage is correctly done, it anchors a thematic continuum which relates smoothly to the flow of the music.

kw - Kilowatt.  A rack of dimmers of 144,000 watt capacity is known as a "144k rack".

LED - Light Emitting Diode.  A low power consumption indicator light used in a wide variety of electronics applications.

load-in - (noun)  The sequence of events which starts with cracking a truck,  and ends when all of the gear is in the room.  Often shortened to simply "the in". "An out" goes the other way: from the room to the truck.

mix - (noun) 1. The set of control arrangements designed for best audio performance. Can include many different signal types and levels.  Can refer to one of any number of control arrangements: typically, audio engineers arrange many mixes as "sub-mixes", which can then be arranged in related groups.

(noun) 2. The place where mixing occurs.  Usually at f.o.h., although sometimes specified, as in "the monitor mix".

(verb) 1.  The act of arranging a mix.

monitors - A special set of equipment which enables a performer to hear his or her own performance in the high-volume environment of a modern concert stage. A monitor is typically a speaker which is placed in relatively (sometimes quite close) proximity to the performer. It often delivers the sounds of any other desired players (a mix), at the desired level.

See Jacksonville for a detailed description of monitors.

mulit-core - A single cable with a relatively large number of conductors, delivering a multiple of signals through a multiple of independent channels.  For example, R.A. Roth uses a cable with 36 conductors for delivering dimmer output to up to 16 individual instruments: 16 hot lines, 16 neutrals, and 4 grounds.  This cable is roughly the diameter of a "C" cell battery. It uses a single connector (Pyle-National Star series) with 37 pins as contact points (1 spare).

Considering all of the thousands of connections to be made everyday on a modern touring stage, life as we know it would be impossible without  multi-core cables and connectors. The variety of type of multi-cores and connectors is huge: each hardware vendor has its own systemic preferences.  Some of them approach standardization across the industry. Others are completely alien between companies. To the untrained eye, a backstage working space, with all of its varied types of cables and connections, appears as hopelessly confusing.

The best touring pros make it a point of pride to keep their cabling groomed as neatly as possible. This practice can pay off in a diagnostics crunch: when the show is rocking along full speed, (perhaps with pyro blasting away) in the high-noise, low-light conditions backstage, the effort to find a specific goof by flashlight can be difficult enough, under the best of circumstances. If one's lines are laid out neatly, the seconds which are saved in the hunt can make the difference between a successful cue and a blown one.

neutral - In electricity, this is the side of an AC circuit which carries electrons back to the point of their generation. It does not carry live electricity: a meter placed between ground and neutral will not (normally) indicate voltage.  However, it is essential to a complete circuit: nothing works without it.

PAR - Parabolic Aluminized Reflector. This is a sealed beam (much like a car's headlight) halogen lamp. A PAR 64 is about 8 inches in diameter.  They are manufactured in four different beam focuses: Very Narrow (1), Narrow (2), Medium Flood (5), and Wide Flood (6). The differences between the types are found primarily in the parabola section of the reflector.

patch - (noun) 1. A particular set or arrangement of connections. For example, a "dimmer patch" refers to connection of certain instrument circuits to certain dimmer outputs.  A "control patch" refers to connection of specific control channels to specific dimmers.  This sort of thing does not proceed at random.  To control a specific instrument, with a specific dimmer, through a specific control channel, everything must be arranged in the proper designated order. In a system involving several hundred dimmers, this can be quite complex.  Modern digital systems allow computerized  control patching. Dimmer patching must be done manually.

(verb) 1.  "To patch" is to actually make the proper connections, whether manually or with software.

pipe - A piece of steel pipe, often 2 1/2" diameter. Pipes are used in a variety of lengths for hanging scenery, drapes, lighting instruments, etc. A theater normally has any number (up to hundreds) of them hanging over the  stage. A pipe with lights hanging on it is known as an "electric pipe". One with drapes or other items on it is called a "batten". They can be lowered or raised ("flown") to facilitate hanging and focus. They usually hang across  stage: one end of the pipe at stage left, and the other end at stage right.  They are closely spaced, up and downstage, to provide relatively precise hanging options.

Pipes are also used on the floor, screwed into an appropriate base, as booms.

Often, a chunk of pipe of indeterminate length (until your eye falls on it: "Yeah! That's what I need!") is very handy for hipshot fabrication during rehearsal or pre-production.

pool - The circle of light which an instrument, or a number of them, throws to the deck. Some instruments, like ellipsoidal spotlights, can throw a pool with a crisp, sharp edge, by means of lens trains which may be focused. Others, such as PAR's, throw a pool which is soft and fuzzy around the edge.

preset - Any analog or digitally programmed arrangement of control settings which can be recalled with a single control action. The single point of control is called the preset.  For example, a complex setting of any number of lights control channels, set at various levels, can be preset for instant single point control.  The same principle can be applied to control of robotic instrument functions (position, color, intensity, etc.).  Audio engineers also use presets in their control operations.

proscenium - A specific type of theater form. A proscenium theater is one which affords the audience only one view to the action: from the  front of house. This view is through the arch over the opening: the proscenium.

rack - A piece of equipment designed to carry other, smaller, pieces (usually electronics) in a single, road-ready, package. For example,  dimmers are often racked 72 channels at a time.  In audio applications, amplifiers are racked in clean packages which allow quick, simple,  deployment and operation. Internal control and power networks need not be individually patched every day.  

Racks save time and effort...unless, of course, something goes wrong inside one. The sight of a group of techs standing around, staring, as the  realization that a rack must be torn down sets in, is a forlorn one.

riser - A small unit of staging which stands on the deck. Often used to elevate drum kits, keyboard stations, etc. Also used at f.o.h. to elevate mix consoles above the sightline which a crowd can reach to when they stand up.

set - (noun) 1. A piece of scenery or staging which is in place throughout the performance.  Modern concerts often make use of complex sets involving integral lighting, hydraulics, turntables, etc. The En Vogue set was not that  complex. However, almost any set presents challenges to lighting and performance blocking.

2. (noun) A designated position.  To "set" an object is to put it where it belongs in the design.

3. (noun) The selection of songs to be performed during a show.

sightline - Literally, a line of sight.  Sightlines are very important considerations on any stage. Just as certain things must be included in certain sightlines, other things must be hidden from certain sightlines.  This can make seemingly remote considerations (such as rigging at 8:00 am) very important.

signal - Generally, any special voltage or data traveling along a given circuit. AC is not normally referred to as a signal. Almost anything else can be. Normally implies a special relationship between "sending" and  "receiving" devices, e.g.: control desk and dimmers, or microphone and amplifier.

sound check - The hum-head torture hour.

This is the point in the day when the audio rig is completely assembled and ready for tuning. A sound check, to me, is officially marked at the first moment when any sound comes out of any speaker, anywhere. From then on, the venue is subject to unpredictable explosions of sound at the whim or thoughtful teleology of the hum-heads. Sound checks may include (but are not limited to): a single guy sitting at the house desk with a single mic, making various and arcane baby noises in order to check delay settings; "Humble Pie Rockin' The Fillmore" on CD through the house system at jet-fighter volume; a monitor guy wandering around the stage with a wireless mic, screaming "Check, one-two..." at his floor wedges and side fills, as loud as he can get them; backliners making clumsy or skillful noises with various instruments; the band actually playing a song in order to hear what they will hear during the show. This last item can sometimes take the dimensions (and duration) of a full rehearsal.

To lights guys, sound checks are, at their most benign, an irritation.  They usually take too long, and they get in the way of effective communication.  At their worst, sound checks can cause otherwise rational people to flip over the high side.

stage directions - A system of directional references which relates exclusively to the stage. They can be very important to finding one's way around.

The earliest stages (Greece) were tilted, or raked, toward the audience.  Thus, the directions, upstage and downstage. This particular reference survives to the present day. To move toward the audience is to move downstage.  To move away from them (toward the wall at the back of the stage) is to move upstage. Lateral directions are referenced to facing the audience.  Thus, stage-left is a very specific place, no matter which way one happens  to be facing.

Stage directions are very different from house directions: stage-left and house-left are precisely opposite.

strike - To tear down and remove an object, from a single instrument, to an entire production.

torm - ("tormentor") A lighting structure which hangs vertically.

trim - (noun) The show position of an object, normally referring to things which are flown.  In lights, the trim of an object (say, a truss) is the height it is designed to fly at. Trim can be preset. In the case of a mirror ball which is to be flown into sightlines for a single song, its trim is marked before showtime. It is then flown out of sight. On cue, it is then flown "in to trim".

(verb)  To set the trim of all the various flying objects, is to "trim the show".

truss - A load bearing structure of specific design.  I hate to do this to you, but see Columbus.  I can't describe it any better here.

wing - The space just off of the stage, to either side. In a proscenium theater, wings are a natural space created by the proscenium wall.  They exist behind (or upstage) of it.

In an arena, which requires erection of a deck stage, wings must be added to accommodate equipment which resides off stage to the sides  (dimmers, monitor world, amplifiers, etc.).


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