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Sound Reinforcement - Forums for Live Sound Professionals - Your Displayed Name Must Be Your Real Full Name To Post In The Live Sound Forums => LAB Lounge => Topic started by: Nate Armstrong on June 18, 2012, 02:29:01 PM
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First off I am a firm believer in using DMX cable for lighting. That being said
I do a lot of lighting and some audio. I thought that a I read a post on this forum saying its ok to use DMX cable as a mic/ audio cable but not the other way around. I have searched for it and could not find the post.
As a lighting guy I tend to have a lot more dmx cable than mic cable, I have never had to resort to using a DMX cable as an audio cable but have been curious if it would be acceptable to do if I had no other option.
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First off I am a firm believer in using DMX cable for lighting. That being said
I do a lot of lighting and some audio. I thought that a I read a post on this forum saying its ok to use DMX cable as a mic/ audio cable but not the other way around. I have searched for it and could not find the post.
As a lighting guy I tend to have a lot more dmx cable than mic cable, I have never had to resort to using a DMX cable as an audio cable but have been curious if it would be acceptable to do if I had no other option.
Yes. DMX cable is fine as audio cable, even digital audio cable, audio cable is not necessarily fine as DMX. DMX and digital audio care what the characteristic impedance of the cable is, audio does not.
Mac
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The only thing I don't like about some DMX cable is that it's stiff and doesn't lay/coil nicely. If you've got the "good" stuff, and especially if you use it a lot, you should be fine.
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The only thing I don't like about some DMX cable is that it's stiff and doesn't lay/coil nicely. If you've got the "good" stuff, and especially if you use it a lot, you should be fine.
From what I have read, DMX is data cable and has a fully braided shield. That is what may cause the stiffness.
Also, I have read in many "entry-level" DMX controller manuals the the shield lead is NOT to be connected connected to the body of the XLR connector. This may be a problem if you try to use it as a MIC cable.
-Dennis
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From what I have read, DMX is data cable and has a fully braided shield. That is what may cause the stiffness.
Also, I have read in many "entry-level" DMX controller manuals the the shield lead is NOT to be connected connected to the body of the XLR connector. This may be a problem if you try to use it as a MIC cable.
-Dennis
No... the drain/ground wire should be connected to Pin 1, but NEVER to the XLR shell.
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Only time I ever tried DMX cable as a mic cable, I got mariachi music through the system. And that's not a euphemism; I think I was picking up a Mexican AM station or something. It was loud and clear.
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Only time I ever tried DMX cable as a mic cable, I got mariachi music through the system. And that's not a euphemism; I think I was picking up a Mexican AM station or something. It was loud and clear.
there was a problem with the cable then
in terms of characteristic impedance of a cable, audio (at least analog audio) rarely cares as long as the cable is wired correctly.
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FWIW, I have a small 8-light DMX rig and I use Road Hog mic cable for it all the time. Don't own any DMX cables. I'm fairly sure I've run DMX through a 100 foot Whirlwind snake, up to 100 feet. Never had a problem and I don't even terminate the DMX chain (lost the terminators),... My cheap controller (DMX Operator 192) and cheap lights don't seem to care...
I rarely take out the lights anymore, no room in the truck....
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Mark, this has been discussed a lot in other threads. I too have done this, but have learned my lesson. I find once you start getting 30 + fixtures and or 250 ft or more one may see some ghosting. I use to use all mic cables. but then I got tired of trouble shooting my rig every show and wasting valuable time. I know use all DMX cables that I have made my self.
I have also moved over to wireless dmx. This makes it easier to trouble shoot because the chains are broken up into 3 sections ( 3 wifi dongles ) instead of one huge daisy chain.
I hardly ever have any problems now. ( I probably should not of said that since I have a show tonight )
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Mark, this has been discussed a lot in other threads. I too have done this, but have learned my lesson.
Yeah me too. When I used mic cables, most of the time fixtures would master-slave (I'm really basic with my lights) but wouldn't you know - when I'd be most pressed for time the slaves wouldn't recognize the master.
It was always a crap shoot. Once I used DMX cables the problem was solved.
But if you have no problem to begin with, you don't have one to solve I guess. Maybe certain fixtures and layouts are more sensitive to this than others.
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From what I have read, DMX is data cable and has a fully braided shield.
I looked at my last few bid specs and mic and line cable is specified as shielded, twisted pair cable with minimum 24AWG stranded conductors, 110 Ohm nominal impedance and maximum 13pf/ft conductor-to-conductor and 26pf/ft conductor-to-shield capacitance. Installed cables are 100% foil shield or minimum 95% braid shield while portable mic/line cordage is minimum 95% coverage 'french braid' shield. Other than 110 Ohm versus 120 Ohm nominal impedance, there is virtually no difference between those mic/line cables and DMX cable.
The point is while there are cable standards related to DMX, "mic", "line" and "audio" simply refer to the signals commonly carried on the cable, there are no related standards and the terms do not define any specific cable construction. Your average music store 'mic cable' may not be appropriate for DMX but that does not mean that is true for everything used as microphone or audio cable.
FWIW, the fact that the cable can potentially be used for analog microphone or line level audio, AES/EBU digital audio and even DMX or data is precisely why I specify such cable.
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You know I don't think I ever bought a "dmx" cable in my life.
I remember when the dmx standard was a five pin xlr. I just made a bunch of adapters 5 pin to 3 and back. I also seem to remember some fixtures used the other two wire for a specific need.
Today I believe everything is 3 pin.
I set up some rather large dmx systems, several universes, lots of mixed fixtures. Never had any ghosting. I usually bring the terminating plugs...and most of the time use them.
But special cable? Naw, not in my world.
But now the idea of a wireless dmx sure sounds like the way to go. Much faster setup/teardown.
Hmmmm.
Bob Cap
Advanced Audio Inc.
Gilbert, MN
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What's the cost of wireless DMX transmitters and receivers? Sounds kind of cool to hang one on each tree and one at FOH,...
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You know I don't think I ever bought a "dmx" cable in my life.
I remember when the dmx standard was a five pin xlr. I just made a bunch of adapters 5 pin to 3 and back. I also seem to remember some fixtures used the other two wire for a specific need.
Today I believe everything is 3 pin.
I set up some rather large dmx systems, several universes, lots of mixed fixtures. Never had any ghosting. I usually bring the terminating plugs...and most of the time use them.
But special cable? Naw, not in my world.
But now the idea of a wireless dmx sure sounds like the way to go. Much faster setup/teardown.
Hmmmm.
Bob Cap
Advanced Audio Inc.
Gilbert, MN
5 pin is still the standard, and any pro fixture will have 5 pin in/out
most fixtures only use pins 1-3, although pins 4+5 are sometimes used for proprietary control systems and talkback protocols
as for wireless, well, you've still got to run power up into the rig, and outfitting every fixture with a wireless receiver gets to be incredibly expensive.
there are some situations where wireless dmx is useful, although my favourite way to get wireless signal is to run artnet over tcp/ip with a convertor box on the other end and/or use a vnc/remote desktop viewer via the internet to wirelessly control my console
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5 pin is still the standard, and any pro fixture will have 5 pin in/out
Not necessarily... Yes, 5 is the USITT standard, but even High End has flip-flopped more times than our biggest politicians... Of the ones I know off the top of my head, Trackspots, the original Cyberlights, and then more recently the Studio 575 series use only 3 pin, whereas the Studio 250 series in the middle of those had both 3 and 5... Other ones I can think of include Martin Mac500s using 3 pins, while Chauvet is using 5-pins nowadays on some of their fixtures.
Just saying, which pin count a fixture uses has little determination on its "pro fixture" status.
It is a shame USITT never specified an actual feature set for the 4/5 pins, like fixture status.
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Not necessarily... Yes, 5 is the USITT standard, but even High End has flip-flopped more times than our biggest politicians... Of the ones I know off the top of my head, Trackspots, the original Cyberlights, and then more recently the Studio 575 series use only 3 pin, whereas the Studio 250 series in the middle of those had both 3 and 5... Other ones I can think of include Martin Mac500s using 3 pins, while Chauvet is using 5-pins nowadays on some of their fixtures.
Just saying, which pin count a fixture uses has little determination on its "pro fixture" status.
It is a shame USITT never specified an actual feature set for the 4/5 pins, like fixture status.
every light you've referenced is a relatively OLD light (pre-2008, when the standard was put into it's final revision). Realistically, DMX is still a relatively new technology, even though it's been the 'standard' for lighting since about 1995. It's not even at the 20 year mark yet, so there's a lot of older fixtures that don't meet the standards.
I haven't seen anything come out in the last 5 years as a 'pro' light that doesn't take 5 pin.
Companies like martin have multiple fixtures lines...one that's marketed to touring professionals and another that's more marketed towards DJs. Same sort of idea as audio manufacturers. JBL doesn't market 4889s to the consumer market just like it doesn't advertise EONs as tour grade speakers.
Generally the cheaper, consumer lines will take 3 pin, where as the 'pro' lines will have both 3 and 5 pin for options, as once you've reached the level where you're buying into fixtures in the $2000 each or high range, you've got enough knowledge to use the proper cabling with them.
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What's the cost of wireless DMX transmitters and receivers? Sounds kind of cool to hang one on each tree and one at FOH,...
around $125 - $175 each. I own 4. 1 at foh, one on each tree and one on the truss. I think im going to get a 5th one. for when I do 2 totems and 2 trees
one of my best purchases to be honest.
cleans up the stage a lot, I know longer have to ask to patch in to the foh snake. infact I dont really make any run to foh, the sound guy is ok with my hooking my laptop and controller to his power because its isolated by the wireless. setup and tear down is a lot quicker now and I have not really had any dmx problems since switching to them.
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You know I don't think I ever bought a "dmx" cable in my life.
I remember when the dmx standard was a five pin xlr. I just made a bunch of adapters 5 pin to 3 and back. I also seem to remember some fixtures used the other two wire for a specific need.
Today I believe everything is 3 pin.
I set up some rather large dmx systems, several universes, lots of mixed fixtures. Never had any ghosting. I usually bring the terminating plugs...and most of the time use them.
But special cable? Naw, not in my world.
But now the idea of a wireless dmx sure sounds like the way to go. Much faster setup/teardown.
Hmmmm.
Bob Cap
Advanced Audio Inc.
Gilbert, MN
Wow, I hope you don't post this in a professional lighting forum like Lightnetwork. Whatever works for you.
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Wow, I hope you don't post this in a professional lighting forum like Lightnetwork. Whatever works for you.
Wow. I hope I don't piss off the lighting gods...
I have a BSEE degree and have been in this business since 1971. A little before dmx.
Yeah what ever works. Or is it what ever the marketing boys want you to believe?
Cost of a good mic cord vs a dmx cable?
Yeah. OK.
Everything should be wireless just to piss off (or on) the cable guys...:)
Bob Cap
Advanced Audio Inc.
Gilbert, MN
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I will agree with you 100% on the wireless DMX though. I bought a cheap ($300) 2.4GHz set several months ago and it worked absolutely great on the two week theatre production and the 1 day graduation ceremony I used it on. Saved a lot of time and effort running a DMX cable from stage to FOH (about 150'+).
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Everything should be wireless just to piss off (or on) the cable guys...:)
the day they make wireless 400a services is the day I quit the business...
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the day they make wireless 400a services is the day I quit the business...
Tesla did this YEARS ago, but it was DC (and looked like a scene out of Frankenstien).
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Scott,
What brand wireless dmx did you buy?
Bob Cap
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Scott,
What brand wireless dmx did you buy?
Bob Cap
None. For my uses, I prefer wires. I was commenting on the wireless 400a power distribution. Tesla was using wireless electrical transmission eons ago, but all of his work was with DC. Edison worked with wired AC (and, obviously, won the market share). I guess sarcasm doesn't translate well in the written word.
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None. For my uses, I prefer wires. I was commenting on the wireless 400a power distribution. Tesla was using wireless electrical transmission eons ago, but all of his work was with DC. Edison worked with wired AC (and, obviously, won the market share). I guess sarcasm doesn't translate well in the written word.
Wrong about Tesla/Edison. Tesla was backed by George Westinghouse, Edison's commercial rival. Edison was the big pimp for DC, the problem with DC was the distribution: line voltage drop (or requiring very high voltage). If Edison had prevailed we'd have had generating stations every 20 blocks.
Edison embarked on a public relations campaign that called Tesla's Alternating Current "Killer Current" and used public killing of animals with AC in an effort to sway public opinion toward DC.
Fortunately the technical merits of AC won out.
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Scott,
What brand wireless dmx did you buy?
Bob Cap
I bought a pair of Sirs-e DMXW2.4 wireless transceivers for under $300 on eBay a few months back. Used them for a theatre production roughly 100'-150' from control booth to first electric. Left them on continuously for over a week and they worked flawlessly. Just used them for a one-off elementary school graduation and again worked great--never a dropout problem. One of them had a missing LED display segment when I received it and Sirs-e replaced that unit super fast with an apology, but I had to pay the return shipping cost. I would definitely buy more of them if I had the need. Each unit can be used either as a transmitter or receiver by flipping a switch. I like the larger form factor; seem to be well-made, discounting the infant mortality LED.
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Thanks for the correction, Tim. I'm into week 4 of my "sleep deprivation studies." I really need to find time to rest - next week is going to be busy....