For over forty years customers have been calling on PNTA for assistance when choosing dimming equipment. With our experience in renting, repairing, and selling equipment by most of the major manufacturers, we can help interpret the data sheets, answer questions, and make recommendations. For some facilities, this involves one or more site inspections to work out installation details. PNTA's Custom Sales Staff is trained and available to help you.
Since a dimming system is often the most expensive item in a lighting budget, it is worth taking some time to investigate and plan carefully. The steps suggested below will help to organize information which is important in choosing the right equipment for your needs.
Think about your current productions and those you plan in the future. How many lighting fixtures do you think it will take to do the job? What types? What is the total number of fixtures and watts required? How many fixtures should be dimmed individually and how many can be grouped together?
Are you planning to combine old and new equipment? What are the makes and model numbers of old equipment that is still usable?
Find out if it's necessary for you to buy equipment which is UL listed. Generally it is not required for small portable equipment which gets its power from wall outlets. Electrical codes usually require UL listing on permanently installed dimming equipment. Check with your local electrical inspector. We recommend that all new equipment purchased be UL listed.
Investigate the power available. Is it single phase (240/120V 1-phase 3-wire) or three phase (208/120V 3-phase 4-wire)? How much power is available 20 amps, 50amps, 200 amps, or more? What else besides the performance lighting is run from this source house lights, sound equipment? (You may need to consult with an electrician for the answers to these questions.) Are you a touring group? What power sources are available at the types of places where you will be performing?
What is your general budget for the equipment and installation? Pick a "ball park" range that is realistic for you.
To make a complete system:
Several parts are required. Dimmers, each with a rated load capacity, are combined into a dimmer pack or rack. The dimmers control the brightness of the lighting fixtures by varying the amount of electricity supplied to them.
The control console sends a signal to the dimmers, giving the dimmers instructions about timing, levels, etc. A manual control console houses both the slide faders that adjust dimmer levels and the circuitry to send levels to the dimmer packs via a control cable. The simplest control console has one slider for each dimmer. Other boards include one or more scenes or pre-sets, which provide duplicate sliders for each dimmer. This allows an operator to pre-set the next look while the first is live on stage, then fade from the first to the next by moving a separate slider, called a crossfader. Manual control consoles may have other special features, such as timers, independent masters, and bump buttons.
Computer control consoles have memory capability and can record each lighting look or cue into memory storage, in addition to offering many other expanded features.
Various cables are needed to complete the system. Load (extension) cables carry electricity from the dimmers to the lighting fixtures. A low-voltage (small wire) control cable transmits the control signals from the control console to the dimmer packs. Power cables bring electricity from the power source to the dimmer packs.
These expandable systems are used for touring shows or in multi-function facilities. They are rack-mounted, wall-mounted, or stacked, with the power input hard-wired for permanent installations.
The dimmers in these systems, generally 6 or 12 per pack, are rated at a specific capacity (dimmers from 1200 watts to 2400 watts are shown; larger capacity dimmers available on request). The rated capacity is given in kilowatts: 1000W = 1kW. For example, a dimmer with 2400 watts capacity may be called a 2.4kW dimmer. These dimmer packs require more power than is available from normal wall outlets.
Most buildings have such power at the main service, in either single-phase or three-phase form. Single-phase power, expressed as 120/240V 1-phase 3-wire plus ground, has 4 wires (2 hot, 1 neutral, 1 ground). Three-phase power, expressed as 120/208V 3-phase 4-wire plus ground, has 5 wires (3 hot, 1 neutral, 1 ground).
The amount of power needed (expressed in amps) varies with the dimmer capacity and intended load. Your electrician or PNTA representative can help to determine how much power is needed and how to get it to the dimmers (power hook-up).
The control consoles in these systems range from two-scene consoles to full computer consoles. Compatibility of control consoles with dimmers depends on the type of control signal. Some consoles use low voltage DC (analog) control. Most memory consoles use a multiplex signal, allowing many dimmers to be controlled by a single cable with only four or five wires. Two standards have been established for multiplex signals, AMX 192 and DMX 512.
The dimmer electronics must match the control signal being used. Several manufacturers make dimmers which can receive either multiplex or analog signals. This allows a facility to begin with analog two-scene control and later expand to hands-on or full memory, without any alteration or replacement of the dimmers. The analog board may still be used as backup to the memory system.
In addition to dimmer pack(s) and a control console, a complete system requires power cables, control cables, cables to connect the lighting fixtures to the dimmers, and in most cases a method for patching.
To patch is to assign lighting instruments to specific dimmers. Often, individual lights are "ganged" together with 2-fers
(see pg. 81), then the load cables from the instruments
are plugged directly into the output receptacles of the specified dimmers. When the number of circuits (cable or wiring from
the lighting instruments to the dimmer) is much greater than
the number of dimmers, a patching system is needed to assign the circuits to dimmers.
DPC (dimmer per circuit) systems with softpatch (electronic patching of dimmers to control channels) are usually less expensive and more reliable than high voltage or mechanical patching. Dimmer packs and memory boards with soft patching, described in this section, may be used as DPC systems in small theatres or for portable use.
When buying a system, select a control board with the total number of channels you plan to have in the system when it is complete. Dimmer packs may be added as funds permit. Note control cable requirements. Be sure the control signal is compatible with the dimmer pack. Power cable and connectors must be ordered on a custom basis.
Large Control Systems
High density dimmers have made it possible to put nearly 200 dimmers, each rated at 2.4kW, in about the same space a dozen required 20 years ago. As dimmer size and prices have decreased, dimmer per circuit (DPC) systems have become popular. PNTA technicians are trained to assist in evaluating the "high end" equipment, budgeting, planning for new installations, writing specification bids, and interfacing/servicing equipment once installed. Contact PNTA's Quotations Department for further information.
Distribution equipment is used to get electricity from the dimmers to the lighting fixtures. In its simplest form portable extension cables are used. In many facilities, however, distribution involves wiring which passes through some type of patching device, and from there, or from a dimmer-per-circuit rack, through conduit to terminate in plugging devices such as connector strips, floor pockets, and plugging boxes. Plugging and patching equipment manufactured by EDI, Union Connector, Altman, Colortran, and SSRC is available through PNTA. Contact our Custom Sales Department at (800) 622-7850 ext 104 for pricing estimates, recommendations, and detailed specifications.