MB 134 – MARCH 2011 – Lighting is experiencing one of the biggest surges among mobile DJs I’ve seen since the first Derby shipped. The surge is likely driven by the rising popularity of event lighting and new-found affordability of LED and intelligent fixtures. Most interesting to me is that the modern movement is fueled by a technology that is celebrating the 20th anniversary of its mainstream acceptance. Hard to believe, but DMX was first introduced in 1986, and was widely adopted by 1991. Updates and modifications have been made to the standard, but it remains generally the same. It is the way mobile DJs use DMX, perhaps, that has changed the most in those 20 years.
DMX as a control protocol is simply that: an electronic means to control devices, primarily lighting. Because it is a universal protocol it is compatible with a substantial number of lighting and effect fixtures. This provides a great many options when addressing niche needs for specific effects. And while this begins to demonstrate the flexibility of DMX, it is by no means where the flexibility ends. DMX software has greatly enhanced the creative control show designers can have over their hardware. Tasks that were once time-consuming and arduous can now be reduced to a mouse click.
BY THE NUMBERS
From a technical standpoint, DMX is merely a stream of numbers packaged as a digital signal. A DMX signal consists of 512 channels (referred to as a “universe”), each of which has 256 possible values. A channel actuates a function on the fixture with which it is communicating. The function is as unique as the fixture. For example, a RGB LED par can may use five channels of control. The first channel might represent the intensity of the red diodes with the 256 values (0-255) translating to 0% to 100% intensity. The second and third channels might control the green and blue diodes respectively. The fourth channel might be a master dimming control, and the fifth could be an “effect” channel. For example, channel 5 might have an option for sound activation that overrides the first four channels. However, this barely scratches the surface of what DMX can control. Moving lights often have 16 channels or more, with channels controlling functions such as pan, tilt, shutter, prism, gobos, color, lamp, iris, focus, zoom, fixture reset and many more.
Along with flexibility, DMX also allows for greater precision in programming. Many moving lights actually use two channels for pan and two channels for tilt. These are often called “fine pan” and “fine tilt” or “16-bit” movements as opposed to the “8-bit” movements possible with a single channel. The reason is simply that a single channel offers only 256 values to control up to 540 degrees of movement. An increase in the DMX value of 1 would cause 2.1 degrees of movement, perhaps too course for applications with long projections or shows requiring precise movements. By adding a second channel for “fine” adjustments to the movements we achieve 65,536 steps of movement (less than 0.01 of 540), which can be VERY precise.
Other fixtures, such as fog machines, might have channels to adjust output, timer functions and other unique capabilities. In essence, the application of DMX is only limited by a manufacturer’s imagination and desire to add functionality to their fixtures. The DMX protocol is simply carrying a string of numbers without any regard to what is connected to the controller.
DMX SOFTWARE: THE KEY TO CONTROL
You can see how this becomes a dizzying amount of information to manage if we attempt to do it purely numerically. A DMX universe has 131,072 possible values at any given moment in time, and we may have multiple universes if we have a lot of fixtures. Running DMX simply by the numbers wouldn’t be any fun at all. Hardware controllers essentially operate this way, leaving the burden on the user to remember what each channel and value does. This is manageable as long as one is operating few fixtures with limited complexity desired in programming. I suppose it’s also fine if you are Rain Man or you have the patience of a saint. I am neither Rain Man, nor a saint. Being of average intellect and highly ADHD, I prefer a faster, easier way. DMX software does for us what software is supposed to do: automate and simplify complex tasks. Could you imagine running your computer with levers and numerical values? It used to be done that way. DOS was an incredible advancement in the ease of computer operation but was still burdensome. The GUI (graphical user interface) offered to us by modern operating systems has allowed the average user to become a power user and do more than computer pioneers ever dreamed possible. DMX software has done the same for the world of lighting.
Rather than remembering color mixing values for our fixtures, or channel and value numbers for gobos, we can simply choose colors by clicking on them, or gobos by clicking on a picture of the image we desire. Movements can now be commanded by mouse, or even recalled as presets. Today’s DMX software packages often include automation features that can make hundreds of channel and value changes behind the scenes with a few mouse clicks, while you, the operator, simply program to your heart’s content, blissfully unaware of all the “math” behind the comfortable interface you’re using.
As a nice bonus, most DMX software packages also offer a 3D visualizer to show us a pretty good representation of what our lights are doing without having to actually connect them. This allows for “offline” programming from the comfort of your desk or couch, while your lighting remains in storage. I do recommend, however, running through your show before the gig with the actual equipment to make fine tunings to movements, colors, strobe rates, etc., as these can vary slightly from the 3D.
With all this power at our fingertips the possibilities are only limited by our imaginations and budgets. The flexibility of DMX allows us to squeeze everything possible out of that budget by helping our fixtures reach their full potential. The same fixtures can be elegantly subtle or extremely exciting, not only from event to event, but also from moment to moment within an event. It inspires me every day when I receive photos and videos from my customers showing me what they have done with this newfound flexibility and power.
A world of possibility is waiting, so step into the light!
Ben Stowe’s love of electronics developed while growing up in a TV repair shop. He helms NLFX Professional (www.nlfxpro.com), sharing his passion for technology through company-sponsored educational efforts designed to help end users get the most out of their equipment. He holds a Minnesota electrical license, an InfoComm CTS and numerous other certifications.
Filed Under: Exclusive Online News and Content, Issues from 2011
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