The Dreaded Mic Cable Question

[badgerman]

So looking around all the answers I've been seeing are something along the lines of "Don't do it, you'll blow everything up." "It'll work, but you shouldn't do it." "Short runs only"

The problem I have is that none of these actually help. Sure I'm biased towards wanting to use mic cables since we've got a whole pile of cables from out non-installed system, but what I'm lacking is specifics. People's stories of what goes wrong (or right) when you use Mic Cables for DMX. What consistutes 'short runs only', short to me is anything under 50feet. I understand the difference between DMX and Mic cables, (shielding and resistance/capacitance), but I also understand that the real world is an imperfect science.

Our setup right now consists of 12 Chauvet LEDRain 56 cans. (and thats it so far) For the most part we'll be running them as uplighting on the backline. Most of the lights we'd try to run with 3 foot patch cables.


I want real world anecdotes.

[Mattotone]

100ft mic snake, 8 dmx pars, 1 8ch dmx dimmer, 4 dmx scanners, 2 dmx moving heads, 1 dmx strobe, 2 dmx effect lights all connected to gether with 3 - 5 ft cables. all cables standard mic cables with a terminator. No issues found so far.

[buttza]

We run 24 LED Bars 13 Channels each connected via 2 - 3 meter Mic cables, 4 iRock 5s connected via cheap 5 Pin to 3 Pin converter cables. 8 LED Par cans using 5 Pin cheap DMX cables. We use a LSC DMX Splitter sending 6 signals and I use no terminators and they run fine for us.
We run 2 x 10 meter mic cables to connect from DMX Dongle to the DMX splitter on stage.I even run probably one of the cheapest USB to DMX dongles around with no dropouts.
I believe they are fine as long as the mic cables are wired correcly.

[badgerman]

aha, ok thanks guys, you've proved the internet wrong.

[Spirit]

I also Use Mic cables and in the end it allways works.

and with in the end, i mean i have had many times that light did not respon or they did there own thing.
But in the end strangly enough everything allways works..:s
But durring Programming i sometimes miss a Couple of light or they dont respon or they reset all the time or they do there own moves.
But most of the time if these Strange Things are happing it's becuase i use 150ft + cable..
With 20xledpar 6xscan ,4 Movingheads , 10x Sunstrips.
But i think a DMX booster/Splitter will do the trick, and i have a lot more stable DMX signal.

But most of the times it works nice rightaway.
and i have seen these problems with Avolight pearl (Expert lightingdesk) and freestyler with enttec pro.
And i allways forget the DMX terminator

/spirit

[wardomon]

All I have is mic cables. Never a problem. I do have a couple of wonky lights. First or last in the chain. Short or long cables. Terminator of not. They have minds of their own. Go figure.

[Kings]

Have only ever used mic cable. Only real problem I see is that mic cable can be treated pretty badly (stepped on, unplugged incorrectly, coiled badly etc) so when I use it for lighting I usually find a dodgy cord. Woudl be nice to have seperate DMX cable that is never exposed to a musicians foot.

[stevo_96]

i use mic cable in a permanent setup,
home made mic-5 pin dmx, use it to link all the moving head fixtures,
never had a problem with signal

that being said, one of my moving heads exploded the other day, but i dint think it was the cable

[Shannon D]

My longest run was with my Enttec Pro connected to a 150 ft snake and then my daisy chain on stage was atleast another 100 ft of cable from the first light to the last. All done with standard mic cables using a terminator at the end. No problems what so ever.

[dmxlighting]

Just to clarify. There really is no problem using 'mic' cables. The key is
'balanced' cables (1 pair and screen). Its all just signal and it will work fine with no real issues.
Purists will spout on about resistance values etc but it will make no real difference.
I am technical manager for an AV company and we use what is known as universal signal cable.
This is used for dmx, audio and mic lines.
The only thing to be sure of is that you have correctly terminated ends.
If they are wrong then u will get strange results but u can't really blow anything up.

[Hambone]

As DMXLighting said, there's no real problem. One big reason many people say never to use mic cables for DMX is separation - avoiding the possibility of connecting audio gear to DMX gear by accident (bad bad things can happen if you do ) It's the same reasoning that many (pro) fixtures use 5-pin connectors even though only 2 pins get used.

[bssmusic]

Well,
as everything, it "depends upon...."
If you use good quality cables, i.e. well shielded and less than 120 pF/m between leads and less than 150 pF/m between lead and shield, it will work. We use up to 50 m of mic cables along with "true" DMX cables and AES/EBU cables.
Much more important is the use of terminator(s) at the end of the line(s).

G
Peter

[dmxlighting]

It's the same reasoning that many (pro) fixtures use 5-pin connectors even though only 2 pins get used.

You mean ' 3 ' pins get used. Not 2 (+,-, Common)

[dmxlighting]

Much more important is the use of terminator(s) at the end of the line(s).

Having never bothered to use terminators I'd say I personally don't think they are very important.
It's one of those 'should do it' but to be honest I don't know anyone who does.

If you are having problems its more likley to be a cable or fixture fault than that of not using a term.

[Hambone]

You mean ' 3 ' pins get used. Not 2 (+,-, Common)

Yup that is what I meant, sometimes the fingers get misaligned typing in the dark

Regarding whether to terminate or not, for small rigs, you're right, it's no big deal if you do or don't. But then again, for as cheap as it is for a resistor and a spare connector, why NOT add that extra bit of peace of mind?

Really though, what it all boils down to is: if it works, that's all that matters, regardless of how one gets there

[badgerman]

Alright so, we've run the rig with standard mic cables twice now (three days, two events). First time, no real issues. We were running 12 Chauvet LEDRain Par Cans with about 250 feet of cables with a homemade terminator. Not super high quality but middle of the road cables. No major issues except losing one light. At the time I thought it was a user error, I was editing a sequence with that light on, while running said sequence and then I deleted said sequence while still editing and running it. The LED was in a corner and just stayed blue the whole night, wasn't bad.

Had a two day event, and we kept losing lights. They would randomly turn Red (and rarely blue, once strobing) and become unresponsive. We would have one or two go at the same time. Sometimes they would go in groups. Two spots together then another two a few minutes later. They didn't kill the show, but it was frustrating. Completely unresponsive and they would come back ONLY after we cycled the power. We were running much closer to 300 feet of mic cables (again not highest quality) with a homemade terminator.

I don't know if it could cause it, but the second day we ran the sound system much hotter than the first, and had far more issues as well. The lights became unresponsive only once the first day, but upwards of a dozen times on the second day. In all likeliness the Cans were on the same circuit as 4 Monitors and two subs. (1500Watts or so) Though, I didn't see any sagging or anything like what you'd expect and we didn't blow any breakers.

We're using the DMXKing.com UltraDMX 3Pin interface.


I just wana know, is this typical mic cables with long runs problems? or a problem with our cans? Is it typical for the cans to become unresponsive? I was expecting them to just start flickering or randomly changing colors because of corrupted data values.

Thanks,

[dmxlighting]

Probably nothing to do with the cables you used. Could be noisey power problem. DMX is at best a terrible protocal that is subject to interferance in poor power conditions like generators that are badly earthed or if a power line has a large applience on the same phase like a big fridge. Also its always worth remebering that fixtures do for whatever reason have off days when they just don't wanna play ball.

One thing to note is that in the past I have acually found some fixtures (by chauvet!) that have an allergic reaction to other fixtures on the same dmx line. Its a bit weired but it does happen!. One way around that problem was to split up the fixtures by using an opto isolated dmx buffer / splitter.

An other note is that one of the cables you used could have a fault. Remember that because DMX is a bit volatile, a cable fault could should up an error elsewehere on the chain any from where you think it will be!

Been there, seen it, done it, got the T-shirt.

I love DMX! (Dirty 485 as I like to call it! )

(RS485, an old old american comms protocal is what we all call DMX, digital multiplex) - Free history lesson!