Six Dimmers for a Thriller
A one-act 25-minute thriller is performed in a school hall with this kit and nothing else: six 500 W fresnels on one overhead bar 4 m upstage of the proscenium, four PAR 64 cans on two side booms, a 12-channel manual desk, and a six-way dimmer pack fed from a single 13 A ring main; two non-dim 13 A sockets are also available at the back wall. The stage is 8 m wide and 5 m deep with a 6 m proscenium. The play has two acting areas, a solicitor's office downstage right and a corridor upstage left, plus a blackout at the climax when the lights fail inside the story. The script requires an actor to switch on a practical desk lamp on the office desk at a specific line, and that same lamp must go out with the blackout. The hall has no blinds and the show is at 7 p.m. in June, so daylight is still coming in.
1. Assign the ten lanterns to positions and purposes, and explain how you patch them onto six dimmers, stating clearly what you lose.
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Assignment.
- Fresnels 1 and 2: paired front light onto the office area, soft-edged, for faces.
- Fresnel 3: steep top light into the corridor, upstage left, so bodies cast shadows forward.
- Fresnel 4: a cool general wash across the whole stage to kill the June daylight look.
- Fresnels 5 and 6: one as a tight special on the office desk, one as backlight on the wall where the actor is pinned in the climax.
- PARs 1 and 2 (stage-left boom): low side light and a narrow corridor slash.
- PARs 3 and 4 (stage-right boom): cross light and a hard backlight for silhouettes.
Patch. Ch 1 office front pair; Ch 2 corridor top; Ch 3 cool wash; Ch 4 all four PARs together; Ch 5 the practical lamp; Ch 6 the desk special and the wall backlight paired.
What you lose. Independent control of the two PARs per side, so the corridor cannot be lit from one side only; no separate balance between the wall backlight and the desk special, which must always rise and fall together; and no smooth crossfade between areas, since the office front pair is one channel.
Power check. Six 500 W lanterns is 3 kW, which is right at the limit of a single 13 A ring main at 230 V. Do not run everything at full; confirm with the caretaker which circuits are shared before rigging, and leave the practical on a dimmer rather than adding load to the non-dim sockets.
2. How do you rig and control the practical desk lamp so it switches on at the right line and dies with the blackout, given the limited outlets?
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The requirement pulls in two directions: the actor must control it onstage, and the blackout must extinguish it. A lamp plugged into a non-dim socket satisfies the first and fails the second, because it stays lit while everything else goes to zero and the illusion of a power cut collapses.
Solution. Put the practical on dimmer channel 5, brought up to full at the preset. The actor's own switch then turns the lamp on at the line, and the blackout is achieved by fading channel 5 to zero with all the others. Two switches in series, one human and one technical, and both must be up for the lamp to be lit, which is exactly what the story needs.
Checks. Confirm the lamp is dimmable: a mains filament bulb dims cleanly, an LED may flicker or drop out at low level, so test it before the tech and swap the bulb if needed. Cable the lamp from the nearest dimmer outlet along the back wall, matted and taped where the actor walks, with a strain relief at the plug.
Fallback. If the lamp cannot be dimmed, use the non-dim socket with a crew-operated kill switch on a clearly spoken cue, and rehearse the cue at least three times, because a human switch is slower and less reliable than a fade.
3. Write five lighting cues in order, giving the trigger for each and the state it produces.
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Q1, preset, before the audience enters. Office lamp off, cool wash at 40 percent, corridor dark, PARs at 20 percent. The stage is visible but unwelcoming; this also masks the daylight spill in June.
Q2, on the line 'You had better come through'. Office front pair up to 70 percent, corridor PARs up as the actor crosses, channel 5 at full so the practical will work when the actor switches it. Trigger is verbal, so the operator must follow the script, not the blocking.
Q3, on the offstage door slam. Corridor snaps to top light only, office dips to 30 percent. The sudden narrowing tells the audience the space outside the office is now dangerous.
Q4, on the line 'Then say it.' Everything down to 15 percent except the desk special at 60 percent and the practical still on. This is the moment before the threat, and the visual message is that the room has shrunk to a desk and a lamp.
Q5, on the actor's hand reaching the door handle. One-second fade to blackout on all channels including channel 5, with a thunder or switchgear sound cue, held five seconds. Because the practical is on a dimmer it dies with the rest, which is the effect the script demands.
Note the pattern: every cue is triggered by a spoken line or a physical action, never by an arbitrary count, so the show survives a slow night.