A DMX Lighting Question.....
- Thread starter qdupsoundz
- Start date
Hahahahaha... Right back at you smarty pants.
But a DMX cable is not a DMX cable unless it has 5 pins on it. Period. During all my conversations with those that wrote the spec, they are clear that DMX cables must have 5 pins (for future, but now current, application).
Otherwise, yes there is a difference between mic cables. But they are still mic cables. Not all mic cable is 70 Ohm. But anything with 3 pin XLR plugs on it is not a DMX cable, no matter what is between the plugs. Just as I could put the correct cable between two parallel adapters and it is not an RS232 cable.
That being said I often use good quality audio cables (110 Ohm, properly shielded) for DMX transmission. Then again all the venues/artists I work with only use high quality audio cable, so the two are interchangeable. This does not make them DMX cables, but they are fine for DMX transmission. I would never use a 70 Ohm audio cable for DMX transission over 10' or on more than a handful of units and I would never recommend any of my clients do that.
And no I would not use mic cables for RS-232. But why do we use non-DMX cable to connect DMX units?
I can get good quality mic cables (110 Ohm properly shielded) for about 1/2-3/4 of what a 3 pin "DMX" cable costs,so why wouldn't I use them, when all Chauvet, AMDJ, etc are selling is good quality mic cable?
Mike
well Q'd Up started the discussion what did you fix? You going to lay your vast experience and knowledge above all and give the problem closure? I'm anxious to see the mystery solved.
Sorry, I meant I fixed the post that started the what is a DMX cable discussion. Not the OP discussion.
Mike
Mike, what about the "Pin 1 problem"? 110 ohm audio cable, is that AES/EBU (also known as AES3)? And when you say "properly shielded" can you elaborate on the type of shielding your mic cables have, and where and how it is terminated? I'm not being contentious, but I think this is an excellent opportunity to put this out for those who are lurking and learning.
As for the standard.. well.. it is the standard and neither you nor I wrote it. We can debate it all day long, but the fact is that the standard is clear on both the connector AND the electrical properties of the cable. I concede the a 3 pin XLR does not meet DMX-512A, and Doug will concede that it won't stop people from using it, but both of us agree that using mic cable is not recommended or acceptible. The dangerous thing here is for people to misunderstand the impedance and shielding properties of a cable and assume that all cables are created equal. They are not. A 24 ga non-twisted pair spiral shielded cable will spell doom for your demuxers in an inductive or EMI heavy environment. Again, don't take my word for it... read the hundreds of white papers on it. I didn't make this stuff up.
Ben
As for the standard.. well.. it is the standard and neither you nor I wrote it. We can debate it all day long, but the fact is that the standard is clear on both the connector AND the electrical properties of the cable. I concede the a 3 pin XLR does not meet DMX-512A, and Doug will concede that it won't stop people from using it, but both of us agree that using mic cable is not recommended or acceptible. The dangerous thing here is for people to misunderstand the impedance and shielding properties of a cable and assume that all cables are created equal. They are not. A 24 ga non-twisted pair spiral shielded cable will spell doom for your demuxers in an inductive or EMI heavy environment. Again, don't take my word for it... read the hundreds of white papers on it. I didn't make this stuff up.
Ben
The LEDs have no problem being dimmed, its the fixtured as when you do not supply the 120V, the transformer does not provide the 7805 with enough voltage to properly operate the PIC that runs the LED fixtures. Its not the LEDs that have problems going off and on, it the entire fixture.
I agree 100% Ben. If you are going to deviate from the standard (in any way be it plugs or cable) then you need to know what you are buying and what you are using.
I look for 22AWG stranded copper, PE insulated, with Duofoil jacket. I believe it is the same cable that American DJ/Elation, Chauvet, and others sell as 3 pin "DMX" cable.
But you are correct, you can not just plug any cable into a light and expect it to work.
Mike
I apologize. I meant LED as in the fixture, not LED as in a singular (or multiple) Light Emitting Diode(s).
Bad communication on my part. I apologize.
Mike
gee Mike perhaps you might join me back to school like Rodney Dangerfield in Vegas in mid February. Speaking of Communication I happen to know Ben will be speaking on such issues at the show and the NLFX Pro Academy it might help in communication skills. Standards are standards and really arent up for debate.
Exactly John! Which is why anything with 3 pins on it is NOT a DMX cable no matter what it is sold as. This is about my 4th conversation this week on the subject. I wish manufacturers would quit putting 3 pin plugs on their units. Clear up all this confusion out there. Also Recommended Practice for DMX512 by Adam Bennette should be required reading.
Mike
PS My next trip to Vegas will be in October. ;-)
Mike, I wholeheartedly agree with you... but they do. Even the likes of Martin are guilty of this sin. Clay Paky assigned power to pins 4 & 5, and THAT was in defiance of the standard. Since I cannot control the connector the manufacturers put on their units I just try to make sure my data and ONLY my data gets from the controller to the lights and that it arrives at the light with the closest approximation to how it left the controller.
Ben
Ben
the English language like electrical communication is so fascinating providing signal that somehow doesnt reach the other source properly.Could this debate actually be an agreement disguised as two seperate signals?
Or more a matter of semantics Jon. To me if something does not meet the full specs it can not be given the full name. So that anything with three pins on it is not a DMX cable. So if you are using 3 pin cable for your data run you are using mic cable. Period, end of story.
Now all mic cables are not created equal. Some are okay for DMX and some are not.
But unless you are running a cable that meets the full specs as outlined by ANSI (and USITT before them) you are not running a DMX cable.
Mike
But we must all live in the practical world. I often use mic cable (3 pin DMX or whatever you want to call it) because I have to. But the mic cables I use are the same as the ones sold as "DMX" cables. But to me they are still mic cables.
Now all mic cables are not created equal. Some are okay for DMX and some are not.
But unless you are running a cable that meets the full specs as outlined by ANSI (and USITT before them) you are not running a DMX cable.
Mike
But we must all live in the practical world. I often use mic cable (3 pin DMX or whatever you want to call it) because I have to. But the mic cables I use are the same as the ones sold as "DMX" cables. But to me they are still mic cables.
so with your train of thought these lights with three pin in fact arent actually DMX lighting? You cant say one without the other. they are in fact Mic Lights. Okay thanks for learning me.
Oh that English language again! You are right, they are not truly DMX lights. Either their manufacturers should put 5 pin plugs on them or we should invent a new name for them. That being said, I don't use the term "dmx light" and have never known anyone in the industry to use it. A light can be DMX controlled, it can be a moving light, or a LED light, or a CMY light, but I would never use the term (and I have never heard it in the industry) "DMX light" because that would be an incorrect use of DMX.
Just like no one in the industry will ever use the term intelligent light. That is always the sign of a newbie.
Mike
how long have you been in the industry Mike? So its sort of like the restaurants who claim Home STYLE cooking.
Over 10 years (but not quite 15). Long enough to have studied under some of the guys who helped write the standard, who developed the moving light as we know it, and to have studied (and worked with) with some of the leading minds in the design world and R&D world of moving lights. Long enough to know not to call them "intelligent" lights or "DMX" lights. Although I know 10 years is only 1/3 of the total time that movers have been around (1/4 if you count the earliest attempts at movers), I pretty much cut my teeth in the explosion of moving lights in the mid-late 90's.
Don't try to use my age as a counter point. That reeks of desperation. ;-)
Yeah, if you wanted to call them DMX style lights, or almost DMX lights, or sort of DMX lights that would be more accurate. But DMX lights is inaccurate since they don't live up to that name. Perhaps this is why that is not an industry term?
Of course if one wanted to one could say that moving light isn't full descriptive of what most of these units can do (and is just wrong when applied to units that do not move), but I would rather under describe a unit than over describe it.
Mike
Don't try to use my age as a counter point. That reeks of desperation. ;-)
Yeah, if you wanted to call them DMX style lights, or almost DMX lights, or sort of DMX lights that would be more accurate. But DMX lights is inaccurate since they don't live up to that name. Perhaps this is why that is not an industry term?
Of course if one wanted to one could say that moving light isn't full descriptive of what most of these units can do (and is just wrong when applied to units that do not move), but I would rather under describe a unit than over describe it.
Mike