When it comes to plugging in your lights to DMX, ask 5 different people, and you’ll probably get 5 different answers to the question “What cables should I use?”.
To top that off, sometimes you’ll find that lights have 3 pin DMX jacks, sometimes 5 pin, and sometimes BOTH! If you get really lucky, you also might find DMX via a RJ-45 ethernet-style plug!
There’s a lot of confusion out there with how DMX works, what’s needed, and what cables are acceptable – so let’s go slay some myths!
Can I Use 3-Pin Cables with DMX?
The DMX standard was designed with 5-pin XLR cable as the connection for data. This was done for 2 reasons – 1) To distinguish the cables from audio XLR and 2) to leave the last 2 pins open for “future expansion”. There have been a few attempts to use this over the years, but none of them have stuck!
Back in the 1980’s and 1990’s, lighting companies realized that they could use 3-Pin cable for DMX because the DMX-512 Standard only used 3 pins out of the 5 pin cable that it specified for lighting control.
In fact, many of the 5-pin cables on the market only actually have 3 conductors inside – the last 2 pins aren’t even hooked up!
And this is for good reason.
After all, it’s really easy to accidentally plug in the wrong 2 cables together and get some weird results. Audio and DMX are best when they aren’t plugged into each other, so it’s a good idea to keep different plugs on the cables.
However, many entry-level lights have 3 pin plugs. Because only 3 of the 5 wires are actually in use, a 3-pin connector can be used…it doesn’t technically meet the spec, but it’s widely used anyways.
What is the Difference Between 3-Pin DMX Cables and Microphone Cables for DMX Lighting?
You’ve also likely seen DMX fixtures that have 3-pin alongside the 5-pin, or that only have 3-pin DMX jacks.
This leaves you with 2 choices – use the less expensive audio XLR to run your lights or buy 3-pin DMX cable that looks very similar to your audio cable.
Then you go ahead and try using microphone cables to run your DMX lights, and everything works fine.
So what happened to the haters who told you that you can’t use microphone cable for DMX? It works, right?
The truth is, it does “work”….BUT:
The but comes in because, we can get away with using microphone cables for DMX, and it does seem to work most of the time.
However, sometimes this doesn’t work right, and you get problems such as strobing, flickering or loss of signal.
The difference lies in the physical cable itself.
True, real DMX cable that meets the specification must be 120-ohm cable. If you buy a product such as these ones, which is labeled as a “DMX Cable”, it should meet this specification (or else they are lying….which is a whole other issue!)
Microphone cable is a lower impedance (ohms), and the difference in capacitance and twisting ratio makes it terrible for DMX signal.
If this is as mind-boggling and confusing to you as it is to me, don’t worry! Skip to the next paragraph to get the information that you need to know!
DMX512 Cabling specifications are in ANSI E1.27-1 (Portable) and E1.27-2 (Permanent) published by ESTA/PLASA. You can check them out here: http://tsp.esta.org/tsp/documents/published_docs.php (Thanks to Scott Blair for the link)
What Does That Mean?
DMX cable is designed and built for signal at a much higher bandwidth(amount of data) and frequency (above our hearing range). It’s a digital signal.
There are tons of data packets traveling down that cable on a constant basis – this is very different from analog audio signal.
If you use microphone cable, you can and probably will eventually have problems with signal loss, dropped signal or interference. Got it?
So, to simplify that even more, microphone cables do work for DMX lighting, but they are not guaranteed to work perfectly, and problems will probably arise when you least expect or need it to happen, like 5 minutes before doors open for your big production!
I’ve seen it happen and heard many stories of the same. I’ve seen it most when the fixture count begins getting above just a few fixtures and mic cable is being used.
Regardless, friends just don’t let friends use mic cable for DMX!
What you may see, however, is DMX cables that are made from AES/EBU wire. This is digital audio cable, with a 110-ohm resistance, as opposed to around 50 ohms for analog cable – this is just fine for DMX.
Can I Use an Audio Snake for DMX?
In a pinch, it works, and I’ve done it before. But, just like using mic cables, you stand the chance of having issues, so do this at your own risk!
Conveniently, the channels on an audio snake run the proper way to send data down them from your console at FOH, but it’s something that I really, really hate doing!
We’re Installing a New Lighting System. Is There Any Alternative to Using DMX Cable?
If you’re installing cable within walls for a permanent installation, you can use inexpensive Cat5e or Cat6 cable as your DMX wire.
This is actually quite popular in the install business because it’s a more universally known type of wire by electricians and contractors.
However, please note that Cat5e is not suited for setups that aren’t installed, and it generally needs to be placed in the conduit. Again, check the link above to make sure you install it correctly!
What About NSI Microplex? Can I Run That on Mic Cable?
Microplex, on the other hand, is analog and designed to work with any old microphone cable, so go ahead and use them.
DMX cables will also work for Microplex, but they have to be 3-pin, of course!
If you do own Microplex components alongside your DMX gear, you need to be very careful in your wiring. Microplex dimmers send back voltage down the XLR cable to power the console.
Your DMX gear may be fried if you plug it into this voltage!
What DMX Cables Do I Recommend?
There are a lot of brands of DMX cables out there. Some are cheap, and not worth your time while others are overpriced.
The best value I’ve been able to find has been from Accu-Cable. They make a decent cable at a great price. Is it pro-level durable? No, but as long as you’re not touring the world with it, it’ll last you a long time!
Be sure to choose 3-pin or 5-pin depending on the fixtures you own! Do keep in mind that if a fixture has both 3 and 5 pin plugs, you may go “DMX In” 3-pin and “DMX Out” 5-pin or vise-versa. You just can’t use these plugs as a splitter!