More and more often I work with industry audio professionals that are interested but hesitant to take the plunge into the world of lighting. After all, nothing elevates a great performance like a professional lighting design. For many the first step can seem daunting, and understanding DMX (Digital Multiplexing) can seem like an overwhelming task. Luckily with a few pointers and key concepts, DMX can be easily understood and an industry professional in any performance technology field will be well versed in no time!

The first step towards lighting enlightenment is understanding what DMX is at its core. DMX is first and foremost a data language protocol used by every major performance technology manufacturer in the world. At some point in event lighting history, everyone decided that it would be convenient to create a control standard that is universally accepted so that no matter what brand make or model of device being integrated; it can still speak the same language as any other DMX capable device. Nifty right? Right! This means that once you have a DMX controller you can control literally any light that claims to be DMX ready. This naturally leaves us with the question: but how?

This is where a lot of audio buffs stop listening because they look at a lighting controller with all its faders and see XLR cables and think that they’ve got it. Yes, DMX is most often transmitted by using cables with XLR connectors. And yes, the cables often look exactly the same as microphone cables, so what’s the difference? The easy answer is that DMX cables use a different resistance level and are not shielded the same way as microphone cables. Because of this, these cables are not interchangeable, and microphone cable should never be used in place of DMX cable except as a last resort (when the show must go on).

Now that we understand that the cables are in fact different, we need to focus on how the signal flows through the system. In an audio system, each component tends to be either generating or transmitting its own individual and unique electrical signal that needs to be mixed and combined into the main output. To over simplify: many sounds mixing into one sound. Lighting is a little different. The controller is a single source of data that is transmitting to many components (lights, hazers, pyro, etc.). To reiterate: one controller transmitting to many components, which is just the opposite of what we are doing with audio. Because of this the cabling path is a little different than audio. The controller is sending a constant stream of data that can command any light in real time. This means the cables can send multiple channels of information over one cable and therefore can be linked directly from one fixture or component to the next in a chain (starting from the controller).

Now how does each light know what command you are sending it? This is where things get tricky. With DMX each channel represents one single parameter of what the light can do (i.e. color, movement, strobe) and a single lighting fixture can take up multiple channels based on how many things it can do. Where a microphone will only ever take up a single audio channel even the most basic DMX lighting fixture might take 6 or more control channels to operate. This means a standard 32 channel audio console wouldn’t even have enough channels to operate more than a few lights if it was even possible. Lighting utilizes a much higher average number of channels.

All DMX enabled devices will have a manufacturer created “profile”. This profile informs us of the number of channels and delineates the parameter that each channel controls for any given fixture. For example on a basic 6 channel LED light the first channel might be a master dimmer, the second could control the intensity of the color red, the third would be the intensity of the color green, fourth intensity of the color blue, fifth intensity of the color white, and sixth maybe a strobe or shutter function. This is very different from audio where each component tends to either utilize a single mono or dual stereo channel. I have attached a few lighting fixture profiles here for you to take a look at and get familiar with what you might expect to see.

Now that we know the profile will tell us what the light fixture does; it is our job to establish which channel the lights first control channel will operate on by setting the DMX “address”. This is a setting you physically set on each individual lighting fixture then also establish on your controller if necessary. The standard single DMX output on a lighting controller is capable of controlling up to 512 channels on one cable and is called a “universe”. Large shows even use multiple universes to accommodate the demand for thousands control channels. Just imagine hundreds of moving head lights each of which use 16 or 17 channels of control.

Lets think about how to apply this information. Maybe you have a two 8 channel LED fixtures, two 16 channel moving head fixtures and a 3 channel hazer. The first light fixture naturally should be addressed to begin on channel 1. We know that it will use 8 channels so we need to appropriately set aside 8 channels on our controller for the first light. Now the second light has the same profile as the first with 8 channels, here we have a choice. We can either group up the similar lights or separate them. To group them up we would address the second light to channel 1 also (you can stack lights with the same profiles on the same channels). This means both lights would behave exactly the same way and control would be inseparable. The other option would be to address the second light to channel 9 (since the first 8 are assigned) so that we can control both of the lights separately. Lets say we opt for the first option above and group the lights together on the same address (channel 1).

Now we have two 8 channel lights addressed to channel 1 and operating on channels 1 through 8. Next we want to address one of our moving-head lights. Since we are only currently using the first 8 channels our first moving head would be addressed to channel 9. This light fixture, as we know, would take up 16 channels. This means if we want separate control of our last light fixture we need to address it to channel 25 and it will operate on channels 25-40. Our hazer would then be addressed to channel 41 and would take up 3 channels. Once your lights have been addressed and you understand what channels they are operating on you are free to control and program them using your controller! Any additional lights you might add in down the road could pick up right where we left off at channel number 44.

It is worthwhile to note that some basic controllers have fixed faders and control the lights based on the understanding that you have addressed and know the profiles of each fixture. This means labeling the board is up to you (have at it audio guys!). Many of the newer controllers however are digitally controlled and have the profiles for many types of lights pre-programmed so that the controller already knows and displays what parameter you are controlling when you adjust the value of any given channel.

Clear as mud? Great! Now you are one step closer to diving into the wonderful world of DMX lighting! Hopefully this article was helpful, and if you have any questions or comments feel free to reach out!