One of the most common questions I get is “Do I Need a DMX Splitter”?
And while I’d like to give a “blanket” answer that covers all situations, it isn’t quite that simple.
In this article, I want to share with you what a DMX splitter does, and then help you decide if you need one, and what type of splitter you need.
What is a DMX Splitter?
The simplest way to describe a DMX splitter is to first talk about what a DMX splitter is not!
Since DMX is a digital signal, you can’t use a Y-cord to split it…This will cause your digital signal to rapidly degrade, and after a few feet in both directions, it won’t work at all and you’ll just be frustrated.
So, in order to split the signal, we actually have to repeat or “copy” it.
A DMX splitter allows you to send your signal in different directions, or to send your signal to more lights.
DMX signal can only run through about 32 lights before it starts to have problems.
Now, this 32 number isn’t a hard-and-fast rule – sometimes it’s a little bit less and it could also be more fixtures. There are a lot of variables at play but sticking to around 16 to 20 fixtures maximum on a given DMX daisy chain is a really good idea.
What Types of DMX Splitters are There?
You may have heard these called a DMX splitter, an optical splitter, optically isolated splitter, isolated DMX splitter, or any variety of names that use some of these terms together.
In general, a DMX splitter both copies the signal and isolates the outputs from each other as well as from the console or computer itself.
Pretty much any splitter you buy is going to isolate the console from all of the lights.
Many splitters will also isolate each output of the splitter from the other outputs.
This is VERY important in case of any malfunctions. Cheap lights (and even expensive ones) sometimes can die, and send rogue voltage down the DMX line. Most consoles do NOT protect against this, but a proper DMX splitter will!
Even if not a total voltage-leaking failure (which is rare, but happens), many inexpensive lights will send out DMX signal if put into “stand-alone” or “automatic” mode, which will cause the rest of your lighting rig to go crazy! I’ve seen these lights do this on their own on occasion, especially as they get older!
If you need to use RDM or Remote device management, you want to make sure that the splitter you get supports passing RDM information back through, or else your RDM will not work.
Other than that, splitters are pretty simple, and pretty much do the same things. There aren’t a lot of options or configuration available, you just plug them it and they work.
Do I Need a DMX Splitter?
In a lot of situations, a DMX splitter is a really handy tool to have at your disposal.
Let’s say, for example, you have multiple lighting positions on your stage.
If you don’t have a splitter, you’ll have to run DMX to the first lighting position, then out of the output of the last light in that position to the input of the first light at the next lighting position, and so on.
Sometimes, this isn’t a big problem or complicated to do.
But, other times it’s a lot easier to just go ahead and buy a DMX splitter so that you don’t have to worry about getting the output from the first position all the way to the second position.
Using a splitter also helps you in case something goes wrong with that first lighting position. If someone accidentally unplugs a light or trips over a cord, you’ll lose DMX signal to all of your lights. But, if you use the splitter and each lighting position got its own fresh DMX signal from the splitter, then only that first position would stop working.
If you’re going to be using over 16 to 20 DMX devices in one “daisy-chain”, you also want to be sure to use a splitter so that you keep your DMX signal nice and strong.
Plus, as noted in the example above – when you have this many fixtures it’s probably going to simplify your wiring anyways to have a splitter. With the amount of money you put into 16-20 lights, the cost of a splitter is quite small and a very reasonable add-on.
Who Doesn’t Need a Splitter?
While DMX splitters are a great tool and really helpful to a lot of people working with lighting, not everyone needs them.
In fact, there are two primary examples when you really don’t need a DMX splitter.
The first is when you’re using lights that have a very high channel count. If you’re using newer pixel mapping moving heads, they may use a hundred channels or more, so you can only fit a handful of these lights per DMX universe. In this case, it makes more sense to come straight out of the console or Art-Net / sACN node and then go to your lights. You don’t need a splitter.
Second, if you only have a couple of lights, then you really don’t need a splitter.
Say you have six lights – unless you need the wiring to split from where your console is to go into different directions, then you probably can just do a straight daisy chain through all of your lights and you’ll be good.
What Splitters Do I Recommend?
If you go out and search, you can find splitters that cost anything from $20 – $1000 – that’s a big range!
A few years ago, an engineering-minded friend of mine shared with me this fact about DMX splitters: they’re very simple, and there are very few differences between the “cheap” splitters and the “expensive ones”.
While you can find the “cheapest of the cheap” models, I don’t generally recommend them because they have poor quality control, and often aren’t properly optically isolated (which protects your console and/or computer – very important!).
So, if you need a basic splitter that works great but doesn’t have RDM support, check out the ENTTEC D-Split. It features 4 outputs, 2 of which are 3-pin, and 2 are 5-pin. You can also get an all 5-pin version here. I own one of these, and many of my students and friends have bought these – they are always rock solid!
If you need RDM support, then my recommendation is the Elation RDMX6S. It’s a great unit, at a killer price considering the RDM support! If you don’t know that you need RDM support, then you likely don’t 🙂 .
I really hope this article has helped you to create great lighting. If it has, be sure to check out other resources on this site, including the free guides that I offer in exchange for your email and Learn Stage Lighting Labs.
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