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Author Topic: DMX Cable  (Read 10282 times)

djdbo12

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DMX Cable
« on: May 19, 2009, 02:52:41 PM »

Hey all, I'm new to the Forum, so excuse me if this has been discussed. I haven't seen it yet. I haven't been doing lighting terribly long, I wanted some recommendations for good cables to use for DMX. I'll need something durable as it will be used on the road. I know Gepco makes a cable, but I don't know anyone that has used it. Most people I know are amateurs as well. (Most of them are using mic cable)
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DMX512

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Re: DMX Cable
« Reply #1 on: May 19, 2009, 08:39:31 PM »

Many amateurs and indeed many professionals use mic cable for DMX512 all the time, and it works well enough most of the time.

Tourflex datasafe is the real deal though.
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TomDale

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Re: DMX Cable
« Reply #2 on: July 12, 2010, 09:21:59 PM »

Newbie correctly mentioned that many use mic cables for DMX512 and yes, they generally work. If you plan on migrating to RDM here's some thoughts: 1) DMX512 doesn't have error checking/logging, 2) DMX512 controllers generally leave slot levels set until overwritten by another value, 3) DMX512 is continually updated, so a light getting a wrong value for 1 scan time (40 msec) isn't likely to be noticed, but synchronized messages involving multiple devices may start getting 'out of sync'.
With RDM there is error checking on the RDM packets so poor/unterminated cables that cause the occasional error will be noticed. Mic cables are designed with a characteristic impedance of ~ 50-70 ohms and since it isn't a critical spec it often isn't even tested for - especially the 'bargain variety' cables, where the actual impedance will change over the length of the cable. If you do use them, use high quality ones. VERY IMPORTANT- most mic cables connect pin 1 (common) to the outside metal of the connector which when plugged into a mic is fine (desireable) but when plugged into two pieces of electrical equipment with possibly differenent earth ground potentials can lead to extremely high ground currents, erractic operation (ground boast) and most importantly - electric shock. Open the mic cable connectors and clip the wire going from the connector shield to pin 1.
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GTS

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Re: DMX Cable
« Reply #3 on: November 04, 2010, 03:46:41 PM »

My company has always used 3-pin XLR cables, although the ones we use are optimised for DMX-512 signals rather than microphone use.  With this, we have never had any problem- any discrepancies that occur in our usual system set-up have been too minute to have any effect on performance.

However, I would strongly recommend an alternative to DMX-512 if you plan to use high-power lasers or pyrotechnic systems, to be safe.
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