Can You Use Microphone Cables for Lighting? DMX Vs. XLR Demystified

Untitled design (4)There is significant debate raging in the world of DMX cables.

Some people are purists and claim that nothing besides a 5-pin XLR is acceptable, but then they encounter pieces of gear that only have 3-pin plugs…that’s not going to work!

Other people go full-out in the other direction and only use microphone cable for their DMX lights, saying that it’s the same stuff!

The fact is, 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”.

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.

You can read more about the specifics of DMX-512 here.

What is the Difference Between 3-Pin DMX Cables and Microphone Cables for DMX Lighting?

DMX cable for stage lighting

Thanks to ryanmilani

So far, we’ve covered why 5-pin is used for lighting, and the specific circumstances that require a 5-pin cable for stage lighting.

But 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 this one, which is labeled as a “DMX Cable”, it meets this specification.

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 lighting deskDMX cable is designed and build for signal at a much higher bandwidth(amount of data) and frequency (above our hearing range).

There are tons of data packets traveling down that cable on a constant basis – not 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!

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?

Church Stage LightingIf you’re installing cable within walls for a permanent installation, you can use inexpensive CAT5 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.

Check out this wonderful guide by ETC for all of the information that you need to know.

However, please note that CAT5 is not suited for setups that aren’t installed, and it needs to be placed in conduit.  Again, check the link above to make sure you install it correctly!

Want to know more about DMX?  Check out “What is DMX512?” for all the info!

What About NSI Microplex?

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!

Do you have a Microplex System?  Learn more about Microplex here!

What DMX Cables Do I Recommend?

Band performs on stageThere 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 Monoprice.

Be sure to choose 3-pin or 5-pin depending on the fixtures you own!  Do keep in mind that if a fixtures 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!

 


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