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Author Topic: DMX over mic cables  (Read 7251 times)

Lyle Williams

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DMX over mic cables
« on: September 27, 2015, 06:06:52 pm »


I know that you are "meant" to use different DMX-specific cable, but using XLR mic leads is pretty convenient.

There have been suggestions that range is reduced when using mic cables.  I don't doubt that, but a question remained for me: how far can I go on mic leads?

I plugged in 400m of mic lead between my controlling PC and the DMX fixtures.  It still worked fine.

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Rob Spence

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Re: DMX over mic cables
« Reply #1 on: September 27, 2015, 07:10:00 pm »

I know that you are "meant" to use different DMX-specific cable, but using XLR mic leads is pretty convenient.

There have been suggestions that range is reduced when using mic cables.  I don't doubt that, but a question remained for me: how far can I go on mic leads?

I plugged in 400m of mic lead between my controlling PC and the DMX fixtures.  It still worked fine.

Audio cable has an impedance to match audio gear. DMX is data like AES is and as such needs cable with the right impedance.

When a connection is made between 2 different impedance cables (audio cable to DMX fixture), it causes reflections (think of it like noise) which when severe will disrupt the data and cause errors.

 So, when you have a bunch of fixtures connected with mic cables, each connection adds a little more noise. At some point your data will be corrupted enough and you will get strange results.

Lots of people cheat and use mic cables. As long as it is working, they are happy. The first show that is ruined because your lights won't behave might cost you a customer or at least frustration, embarrassment and a ding to your reputation.

If the cost of the right cables to do the job is a problem for you, I would think you have bigger problems or at least some out of order priorities.

Don't forget to put terminators on the last fixture in the chain.


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Lyle Williams

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Re: DMX over mic cables
« Reply #2 on: September 27, 2015, 09:55:01 pm »


I guess my point is that if works at 400m, then there is little to be scared about with 40m of cable.
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Jamin Lynch

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Re: DMX over mic cables
« Reply #3 on: September 27, 2015, 10:22:32 pm »

I guess my point is that if works at 400m, then there is little to be scared about with 40m of cable.

Or you can go wireless DMX
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Tom Bourke

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Re: DMX over mic cables
« Reply #4 on: September 27, 2015, 10:51:12 pm »

I guess my point is that if works at 400m, then there is little to be scared about with 40m of cable.
It will work great, till it doesn't.  Those reflections can happen at any change in impedance, for example mixing cable types.  Most instruments just have the in and out tied together.  This means that ALL cables in the path count. Join 4 lights and a controller together with 100ft cables and you have 400 ft of cable with 3 taps and 2 ends.  Lets say 16 lights with 100 ft to FOH and 100 ft cable tree to tree with 4 per tree and a mix of random mic cables in each tree.  Now you have all kinds of fun. Every one of those joints or ends can create reflections.  Changing the order of the cables can change where and how the reflections are happening.  The system will get wonky when those reflections start to interfere with the data stream.  It may be just one of hundreds of possible combinations that can cause problems.

Point being that yes mic cables will work just fine, MOST of the time but not ALL of the time.
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Rob Spence

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Re: DMX over mic cables
« Reply #5 on: September 27, 2015, 11:16:18 pm »

I guess my point is that if works at 400m, then there is little to be scared about with 40m of cable.

Not many impedance changes here. A set of 20' cables to a bunch of fixtures might not.


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TJ (Tom) Cornish

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Re: DMX over mic cables
« Reply #6 on: September 28, 2015, 10:36:47 pm »

Or you can go wireless DMX
For reliability, I would take DMX on mic cable 100/100 times over wireless DMX.
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Jamin Lynch

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Re: DMX over mic cables
« Reply #7 on: September 28, 2015, 11:01:11 pm »

For reliability, I would take DMX on mic cable 100/100 times over wireless DMX.

I've been running wireless DMX for a while now with no issues. I love it. Beats the hell out of running cables.
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Scott Holtzman

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Re: DMX over mic cables
« Reply #8 on: September 29, 2015, 02:09:53 am »

I've been running wireless DMX for a while now with no issues. I love it. Beats the hell out of running cables.
Jamin we have been on the same page lately.  I picked up a box of oem dmx wireless boards and have been installing them in about 15% of my PAR'S and all my movers.  Can't wait until I am done.

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Jamin Lynch

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Re: DMX over mic cables
« Reply #9 on: September 29, 2015, 07:17:45 am »

Jamin we have been on the same page lately.  I picked up a box of oem dmx wireless boards and have been installing them in about 15% of my PAR'S and all my movers.  Can't wait until I am done.

Sent from my SM-T800 using Tapatalk

I've been using the ADJ WyFly transceivers for about a year now. Mounted one on each light bar. Just run power to each light bar and go. I also have the wireless controller. No cable from FOH.

I guess it depends on your situation, but for me it has worked well.
« Last Edit: September 29, 2015, 07:26:01 am by Jamin Lynch »
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ProSoundWeb Community

Re: DMX over mic cables
« Reply #9 on: September 29, 2015, 07:17:45 am »


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