List of Technical Equipment

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Revision as of 18:23, 21 October 2008 by J (talk | contribs) (Types of Lanterns)

NB again: Found this in the old theatre manager's manual, it needs updating but I am typing it here to get rid of the paper copy. Originally written by Graeme Timms I believe.

Types of Lanterns

Fresnels: Fresnels produce a very soft edged beam. The beam angle is adjustable and its shape is roughly contained by a (usually!) rotatable barn door.

There are four types of models of fresnel in Bedlam stock:

  • Patt 123 : The old old Strand fresnel with a 500W T17 lamp, otherwise known as an 'eggpod' due to its shape
  • Minuette F: The old standard fresnel in the theatre with a 650W T27 lamp
  • Acclaim : The new standard fresnel with a 650W T27 lamp, their barndoors rotate freely.
  • Patt 743: A 1KW fresnel with a wider beam angle than the other lower wattage fresnels
  • 2KW fresnel: Otherwise known as 'that ****ing huge light'. This is an old film lantern, and has some idiosyncrasies, including needing two safety chains (due to its weight) and needing switched on at the actual lantern itself. Don't rig it unless you are good up ladders or really need to.

A variant on the fresnel is the pebble convex (or PC) lantern (sometime salso called Prism Convex) which gives a slightly harder edged beam with less spill than the fresnel. PCs are different from fresnels by having a smooth flat front lens rather than the concentrically ridged front lens of fresnels.

Profiles: Profile spots give precise control of the beam. Shapes in all sizes can be produced by integral shutters giving hard edges to the beam or by an iris diaphragm giving round edges. Edge quality can be adjusted from very soft to sharp by adjusting the lens. The quality of the whole beam can be textured by a metal plate called a gobo. More advanced profiles have a zoom facility where both the beam angle and focus can be altered.

New generation profies now have a third lens fitted. This arrangement is termed condenser optics. It allows for a greater output from the lamp and improves projection for gobos. Although the Bedlam does not have any condenser profiles in stock, ensure that any show rentals are consistent with condenser and non-condenser profiles as far as required.

  • Patt 23 mk1: Non-zoom profiles with a 500W lamp. Beware of dropping the lens tube while focussing
  • Patt 23 mk2: Exactly the same as mk1's with a set of shutters fixed. Both are known as 'snouts' due to their shape.
  • Prelude 16/30s: 650W Strand lanterns with a variable beam angle between 16 and 30 degrees
  • T-84's: 1KW Strand zoom profiles. Often used as folo spots in the Bedlam.
  • Source 4 Jnr: Our newest lantern, bought pre-Fringe 2000. High quality beam from a 575W lamp. Variable zoom between 28 and 50 degrees.
  • CCT 1KW profile. We have 2 of these after they were donated to us at the end of fringe 2007. They are very heavy and have a massive yoke, so hang rather low on our rig. They often will take more than one person to rig

Parcans: Parcans are a fixed beam lantern whose beam angle is determined by the lamp in the lantern. These are the classic rock concert lantern and are very effective at producing strong beams of light in smoke or haze conditions. There are two types of can available.

  • Long Nosed Parcans are found in the Bedlam in a black finish. They are also available in chrome finish.
  • Short Nosed Parcans are found in the Bedlam in the form or "Floor Cans" or a par can with a double yoke that can sit on the floor without the need for a floorstand. These are most commonly used as floor mounted parcans providing face light for music gigs or TV such as Later with Jools Holland or TOTP.

There are four different types of lamp available for use within parcans.

  • CP60 lamp gives a narrow beam. These are identifiable from the clear finish to the lens of the lamp
  • CP61 lamp gives a medium width of beam, identifiable by the frosted finish to the lens
  • CP62 lamp gives a wide beam of light. These are distinguished from its counterpart lamps by having a linear ridged finish to the lens, rather like that found on a car headlight
  • CP63 lamp gives an extra wide beam that can really only be used in the short nosed parcans. The Bedlam does not stock these lamps

The Bedlam theatre stocks the first three of these lamps although current stock mainly uses CP62s. Parcan beams are oval in shape with a bright centre line and a slightly less intense edge. The lamp can be rotated to orientate the beam the way required.

Rigging in the Bedlam

Without rigging, lights are almost useless in the sense of theatrical lighting design. It is the most physical part of theatrical lighting and potentially the most dangerous as it involves work with weight at height. It is made even more dangerous in the Bedlam as most rigging is done at well after normal peoples' bedtimes and sometimes well into the early hours.

Use of Ladders: Rigging in the Bedlam should always be done by ladders from the auditorium floor or stage. For work in the auditorium extendable ladders should be used, always footed by a competent person. Ladders should be leaned against the grid bars, never against trunking or any other attachments to the grid. Only use ladders if you feel confident working at such height. If in doubt, leave it to someone with more confidence. Whilst working on the ladder be careful not to over-extend yourself and at all times be aware of those below you.

Means of Rigging: Before rigging a lantern you should preferably check that the lantern is electrically and mechanically safe. Plug the lantern into the dimming channel on test mode to check the lamp and visually check that the plug and cable are in good condition. Also check that the yoke assembly is functional and that no parts are missing or damaged. Should you see any problems with the lantern at all, report it to the Technical Manager and under no circumstances rig the lantern till the faults have been repaired. The reason for checking the lantern before rigging is that it is far easier to fix faults on a work bench than above your head on top of a ladder.

To rig a lantern on a bar you should:

  1. Place the hook clamp over the barrel and tighten the wing nut on the clamp
  2. Attach the safety chain or bond around the bar. This is an important safety feature used in case the hook clamp fails
  3. Ensure that the bolt and nut attaching the lantern to the clamp are tight
  4. Connect the lantern to the required circuit on the rig, ensuring that the plug and socket are fully mated
  5. Ensure that the lantern is burning the correct way up. This is to maximise the life of lamps as they are designed to burn in a specific orientation
  6. Open any barn doors or shutters that the lantern may have

Rigging onto pipes (vertical bars) is similar to rigging on the grid, but you must ensure that the lantern is not on its side. To achievethis a bar or boom arm may need to be rigged to attach the lantern to the pipe.

Pipes can be rigged in the stage cupboards with the help and approval of the Technical Manager. it is possible to rig bars and pipes in other areas of the theatre. However, speak to the Technical and Theatre Managers before planning to do so, so that it can be ensured that the proposal is both safe and complies with the terms of our licence. All pipes rigged out of contact with the main rig must be earthed.

Cabling: Without power a lantern is near enough useless. Power is supplied to the lantern by means of either being plugged into a circuit on the rig or by means of a 15A TRS cable. If the lantern is on the rig, plug it into a circuit and note the number. Tape any excess cable to the rig with PVC electricians tape (referred to herein by its tech name of LX) allowing enough slack so that the lantern can be focussed.

If the lantern is on a pipe or on a floor stand then a TRS cable must be used to supply power. Ensure that the extension cable is of good condition. The cable must be supported by using LX and any cable on the floor must be taped to the floor using gaffer tape.

Power Supply and Control of Lanterns

Dimming: The Bedlam dimming for stage lanterns is provided by 8 Zero 88 Beta Packs. These each have six channels which by two sockets provide up to 2.5kW of power. It is important that these limits are never overloaded. The dimmers are turned on from a fusebox at the far end of stage right balcony. Turn the large red master switch to on and then all dimmers should be active. If not check each dimmer's own RCD on the individual 63A socket. The RCD is an important safety device. If the RCD repeatedly trips inform the Technical Manager as a matter of urgency as this could indicate serious problems with the system. Do not, under any circumstances, attempt to bypass the RCD.

Patching: Each channel in the dimming is assigned to a channel of the LX desk. Each circuit on the rig has a tail at the dimming which can be plugged into the dimmers completing the circuit. Then, when switched on, the LX desk can control the intensity of each lantern individually between zero and full intensity.

DMX: The Bedlam lighting system is controlled by means of a digital control system known as DMX. Each dimmer rack is connected in series by means of a multicore cable, each dimming channel having a unique individual DMX address. This means that all the control information can be sent down one cable from the control desk.

Lighting Control Desk: See Lighting Desk


In terms of theatre sound systems, the Bedlam's sound system is relatively small and basic. However it is more than adequate for the needs of the theatre most of the time. It consists of four speaker cabinets at each corner of the balcony above the balcony, connected via two stereo amplifiers to a 16 channel mixing desk. There are individual components within the system that are as follows.

Compressor: You may have seen compression used on a source with highly variable and immediate changes of volume, such as a radio bug mic or a bass guitar and the mixing desk. The compressor allows a maximum level for that signal to be set and peaks above that determined level are reduced to give a smooth signal. In the Bedlam, the compressor is located in series between the mixing desk and the amplifiers. This is to ensure that if any errors are made in the levelling of the gain on the desk, no damage is done to the amplifiers or speakers by reducing the peak level of signal to reach the amp. Under no circumstances should any of the controls on the compressor be changed from their set levels.

The Mixing Desk: See Sound Desk

The Sound Rack: See Sound Rack

Sources: In the rack to the right of the mixer there are major sources each taking two channels, or one stereo channel, on the mixer (L and R to allow stereo feed). These consist of two minidisc players and two compact disc players. There are two permanent stereo auxilliary inputs to the desk also with the choice of phono plug, large jack or XLR connection. These allow two more sources such as MP3 players, mics, laptops or another MD to be connected. It is however more common to hardpatch laptops or MP3 players into the desk, as we have many unused channels.

Amplifiers: The signal from the main LR output from the mixing desk is amplified through one amplifiers. The signal is sent to the MC2 Amplifier. This controls the upstage left upstage right speakers. On matrix 3 and 4 a signal is taken and inserted into a Carver amplifier which drives the downstage left and downstage right speakers. As both amps are stereo this allows for independent control and usage of each speaker.

Before turning the amps on, ensure that the volume knobs are at 0. Then turn the amp on rotating all four knobs clockwise to around two thirds of maximum. Remember when you set volume levels that noise is far louder in the auditorium than in the tech box even with windows and doors open due to the positioning of the speaker cabinets and the canyon effect experienced in the auditorium.

Speakers: As previously explained there are four speakers, each over one corner of the balconies. They make sound waves. What else is there to say apart from be nice to them and don't make them flutter cos that isn't good for them. They were focused in 2007 for Guards Guards, which involved building proper rigging points and allowing us to actually point the speakers at the audience.

FOH Sound: During Fringe 2007 Neale and Dave installed a cloud zone mixer under the box office counter. This zone mixer controls all sound in the Box Office, Cafe and Dressing room. There are 6 main inputs and 2 mic inputs on the zone mixer, and 4 zones. The zones are

  1. Box Office
  2. Cafe
  3. Dressing room
  4. Spare

The inputs currently are

  1. Spare
  2. Box office CD player
  3. Box Office mini-jack cable(for MP3 player)
  4. Techbox Feed (sent from sound desk on matrix 1 and 2)
  5. Spare
  6. Spare

Zones and input channels need to be double checked.

Patch panel: Patch panels are a piece of equipment that allows different configurations of inputs and outputs to be achieved without having to totally repatch the desk and end up with a large amount of cable trailing everywhere. Although it is obviously possible to explain how it works here the best way of learning about it, as with most other toys in the Bedlam, is to actually use it.

Show Relay: THIS NO LONGER EXISTS The two small speakers attached to the tech box wall can either carry the PFL output from the desk or relay the sound from onstage (using a microphone attached to the wall directly below the tech box). Select what you want to hear by using the switch to the left of the sources rack. The show relay is controlled to the left of the lighting position. A small black box contains the switch and battery for the microphone, and a box on the wall can be used to adjust volume and tone. The show relay, when switched on, also feeds a speaker in the dressing room.

Identification of equipment

See Electrical Tape

Damage to or Non-Functioning Equipment

It is inevitable due to the amount of use equipment in the Bedlam that there is a good chance that some equipment will be either accidentally damaged before, during or after the time you use it. This non-functionality could easily be repaired such as a blown lamp or indicative of a more serious problem. Therefore all incidents of non-functioning equipment should be reported to the Technical Manager. Any cases of blown lamp should also be reported to the Technical Manager as a matter of course so that all lamp inventories can be kept up to date.