Power and Control (or) Don’t Fry the New Toys

Power and Control (or) Don’t Fry the New Toys

LEDs and Movers are fantastic tools for designers, and now that they’ve become a regular feature in many theaters, schools are now embracing them as well for their implied cost and time saving properties (check out last week’s blog, Plugging in the Future). While no more lamp replacement and all the colors of the rainbow and then some are attractive features, there are important facts to understand about LEDs. It’s not as simple as replacing the light bulb.

This is the part that makes people nervous. It’s also where most mistakes happen, so let’s keep it simple.

LEDs need constant power, not dimmed power

Our traditional systems have dimmers of some kind, power regulated by our control panel like a faucet (anyone remember watershed walls?). LEDs don’t operate like a tungsten filament. Theatrical LED fixtures have their own internal dimming and power supplies. Every instrument contains its own on board computer. They’re designed to sit on full voltage and be controlled by DMX, not by your old dimmer curve. goknight.com+1

You can achieve this a few ways.

Plug LED fixtures into a constant power source, like a wall outlet. You’ll want to unplug them regularly. Just like you don’t leave your computer on all the time, the computer components of your instruments will need a break too.

Set a few of your dimmers to non-dim. There are non-dim modules for dimmer racks, or you can park your channels at full in your console. Check your console’s user manual for instructions on how to do this, but for most it is as simple as selecting the channel, entering full or 100%, and hitting the “park” key or function.

Replace a dimming module in your rack with a relay module! If your rack offers relay or constant modules, you can often swap a few dimmer modules for those and power LEDs from the same raceways you already have. Relay modules are fantastic ways to get the best of both worlds in your existing system.

DO NOT plug your LEDs into traditional dimmers and power them from faders.

This will cause flickering and will shorten the life of your instrument.

goknight.com+1

DMX control: one universe, many devices

Your incandescent dimmers and your new LED fixtures can happily share the same DMX universe. Be aware, though, your LEDs will take up a minimum of 2 (for white only) or 5 (for RGBW) addresses in your universe. Where you could run 512 individual incandescent instruments in one universe, if you replace them all with even the most basic RGB unit, you will cut that down to about 100 instruments.

For example, in my inventory I have 77 instruments that are RGBW. Each instrument uses 5 channels, taking up 5 addresses in the DMX universe. One channel is intensity, one is for red, one is for green, one is for blue, and one is for white.

I have 8 moving head wash units that are currently set at 15 channel. Those channel functions include intensity, color, pan, tilt, zoom, as well as a few others like cooling fan and motor speed that I don’t directly modify, but are important to the function of the instrument.

That count alone puts me at 505 of my 512 channels. Adding much more requires a second universe.

A Simple “First LED Project” You Can Do This Season

Let’s make this practical. Here’s a small, realistic first step that works well in a school or small theater:

Project: LED Cyc & Color Wash Upgrade

Basic workflow:

1. Decide what you would like your LED light to do. Cyc wash? Over stage color wash? Side light? This will determine what type of LED lights you look for.

2. Choose starter fixtures. Blizzard, ETC, and Chauvet all make excellent entry level LED units, but you can also find instruments on Gear Source or other used equipment sites.

3. Understand how many universes you have to work with.

4. Give each fixture its own DMX starting address.

5. Patch those addresses into your console (look them up in your library or use “generic” LED or RGB/RGBA profiles in your patch)
   

Goal: Replace your cyc or top light system with LEDs and add a basic LED color wash over the stage.

Shopping list (conceptual):

• 4–6 LED PAR/wash fixtures for overhead or cyc color

• Enough DMX cable to daisy-chain them

• Edison or stage-pin to power them off constant power circuits
  

Step-by-step

1. Choose the fixtures.
   Look for:
   -Theatrical or stage-grade LEDs. You can use DJ lights, but I can tell you from experience, they don’t last long for theater use.
   -3- or 4-color minimum (RGB, RGBAmber, or RGBWhite)
   -DMX in/out and a reasonable number of channels. (Number of fixtures x5) Theatre Crafts+1
   

2. Assign power.
   -Identify a few non-dim circuits or constant/relay outputs.
   -Label them clearly: “NON-DIM – LED ONLY”.
   

3. Hang & address.
   -Hang your LED strips evenly across the cyc or LED PARs in your desired positions.
   -Daisy-chain DMX: console → dimmer rack → LEDs. If you don’t have DMX output at your lighting positions, you will need a wireless relay device.
   -Set DMX addresses in a logical pattern (for example, cyc 1 starts at 100, cyc 2 at 105, etc.). Make sure you are not conflicting with other dimmer numbers already in use.
   

4. Patch the console.
   -Add each fixture into your patch.
   -Use generic RGB fixtures if your console doesn’t have a specific profile.
   

5. Build a few go-to looks.
   -A lavender top wash.
   -Add LED colors: choir blue, dance magenta, sunset amber, a split-color cyc, etc.
   -Record them as submasters or pallets so students can call them quickly.
   

This alone can make your shows look dramatically more modern without touching your existing house rig.

Don’t be intimidated by the new equipment. You’ll learn best by doing. If you’d like assistance, feel free to contact my [email protected] or join the Backstage AIC Facebook group!