Tech Writers: You're giving bad information

Agreed! DMX cabling does work better, although XLR mic cables are probably more convenient. I use mic cables for this reason. Still, I've seen a lot of people run into problems using mic cables and that's the first thing we think of when someone says "My lights are behaving erratically!" We almost immediately ask what type of cable they are using. Usually the problem is the cable, and next is usually a terminator. Either way, I agree you should cross promote the products, it does help!

-Tyler Herron

Convenience or not, there is a right way and a wrong way to do thing. While I am first and foremost a sound engineer, I do lighting out of necessity.

With so much XLR cable in my inventory, using XLR is convenient. Doesn't make it right. ADJ, as with other lighting companies, has a responsibility to encourage and promote good operational methods. That means telling people to use the proper cabling. In the case of ADJ, it helps cross-promote their AccuCable line. Not only can ADJ say "hey, use DMX cabling" they can also say "we even make DMX cabling, so here ya go".

I think one of the issues with DMX cabling goes back to some sort of bad decision some company made years ago. I'm not going to name names as to which company made this decision because I honestly don't know.

Let's look at a bit of history.
XLR has been a standard for a very very long time, using the 3-pin XLR connections, male and female.

POWER for many video components uses a 4 pin XLR connector.

For a bit in the initial conception, MIDI was going to use XLR connections, but since DIN connectors cost so much less ad musicians tend to be broke. To save costs, it was decided to use DIN connectors instead, and standardize on cables being male to male(except in extensions) and connections on equipment being female.

DMX-512, based on what I've been able to read, originally used a 5-pin XLR connector. Yes, some microphones, such as the Shure VP88 and the Audio Technica AE5200 and ATM5200DE also use 5-pin XLR connectors, to break out the two microphone elements via an adaptor cable.

Now, we all know that DMX-512 only uses 3 conductors: shield and and + and -. This means that it CAN be used on a 3-pin connection, leaving 2 pins not used. 5-pin XLR connectors cost MORE than a 3-pin connector. Proof of this is that you can easily buy or make adaptor cables for this. The only hard part is buying the 5-pin, but that's not terribly difficult if you know where to look. Just takes some knowledge you get after being in the industry a year or so and become familiar with the various manufacturers.

So, to save cost, some company decided to go 3-wire XLR for DMX. This was most likely a company like ADJ, who was trying to offer cost-effective fixtures at affordable pricing. This was coupled by retailers not knowing that DMX should have different cabling. Since 3-wire DMX is wired the same as microphone XLR and use XLR connectors, it just adds to more confusion. As a result, people ASSUME(as I did) that microphone cabling works fine. To keep matters een more confusing, it WOULD work, thus there was no apparent need seen to buy DMX cabling, which is no more expensive than XLR microphone cabling. Well, sometimes DMX cabling may be more or less expensive, but usually not by a whole lot, in my opinion not enough to discourage making the right decision.

As we can see, each year thousands of newbies enter the entertainly business. That means that most likely 90% of them are joining and making this exact same mistake: wrong cabling for DMX. Unlike other things, making the wrong choice can be never know for years because they are simply ignorant over this issue.

I had a similar issue recently, with a DJ I work with on a now regular basis. Let's put it this way, the guy is no dummy. He's a good DJ, he's a smart business man. But, in typical DJ form, he's got RCA outputs on his mixer. So, he bought cables that go from RCA to XLR. This DOES NOT balance the connection, merely adapts it. Taking that and running it down a 200-foot multipair cable, that's 200 feet of unbalanced run down balanced cable, plus the 2 25-foot XLR's I had to hook into his adaptor cables, which were at least 25 feet long. Just because it DID work doesn't mean we SHOULD do it. I have bought an adaptor cable for him to use going forward and use a stereo active direct box. No more problems.

Another issue with lighting ties along with ignorance. The DMX Terminator. So many ADJ manuals talk about using and even BUILDING a DMX terminator. Retailers are partially to blame because they don't tell people about this. I mean, how many of these guys working retail are also weekend warriors and doing some of this stuff on the side? They should have better knowledge. It is apparent that they don't. Not only that, but retailers don't carry things like DMX cabling like they should as well as pre-made DMX terminators. I can get the resistor for like 100 for $2.25, ad the male XLR for under $3 if I can get them on sale, and I'm talking about a good quality Neutrik connector too. Going back to supporting the ADJ brand, the Accucable DMX connectors are a fairly sturdy product. I bought I think 10 sets of these and I'm fairly impressed with them. The soldered easily and connected firmly and the parts stay put.

I don't know of any lighting schools. I'm not going to even argue whether or not lighting is easier or harder than audio. The disciplines are different, so they don't fairly compare. I know there is theater lighting courses, but there are also guys who work full time doing nothing BUT lighting.

Education is important. We can start this education with the manuals.

Figured I would chime in and add a few cents since this is heading into a more technical area.

DMX became a standard for lighting control in 1986. It was first revised in 1990, which is when it became more mainstream. It was revised yet again in 1998 when control of the standard pasted from USITT to ESTA. In 1999, it was made the international standard by the IEC. The last revision, DMX512-A happened in 2004 when ANSI took over the standard and clarified a few things.

First and foremost, in order to received certain listings and certifications, fixtures must use at least 5 pin connectors. Some have 5 pin, 3 pin, and/or Ethernet. Secondly, DMX was originally 5 pins because the extra pins were for expansions. According to the DMX512-A revision, those extra pins can be used for another data line and/or communication with fixtures for things like error reporting. These extra pins (4 and 5) have since become known as Enhanced Functionality. Third, the standard states that DMX is 110-120 ohm digital cable vs XLR which is about 300-600 ohm analog cable. Because of this, DMX is easily turned into Ethernet and back again since Ethernet is digital cable.

So, how did DMX end up three pin? Well, hate to say it on here, but it is all thanks to DJs. Some one figured out that you only need three pins and three lines, so that's 40% less connections, wires, and pins then 5 pin cable which ultimately saves money. Basically, 3 pin DMX came about because someone was looking to save a quick buck. Here is where things get hairier. XLR isn't actually a cable, its a type of connector. You can have 3, 4, 5, 6, 7, and I think I have seen 8 pin XLR connectors before. Since 3 is the most commonly used, it took on the name XLR. 4 pin is used for color scrollers mainly, so it is referred to as scroller cable. 5 pin is mostly DMX, thus DMX cable. 6 and 7 pin are used for comm and as such, comm cable. 3 pin XLR and 1/4" TRS are the same thing, just different connectors and the connector determines the name. Likewise, 1/4" TS and RCA are the same thing, but again different connectors so different names.

So there is a little history lesson/technical brief about DMX.

The same concept was used with MIDI, reserving the outer pair (4,5) for additional functionality. Never been really properly utilized. A couple of companies run DC through it for more "keytar" type applications for control and power on one cable. Ain't perfect, and it ain't a solid connection either, but that's the nature of DIN.

I've seen a very FEW times 6,7, 8 and 9 pin XLR's. Holy crap, thats too many pins in an UGLY configuration to repair and work with. I don't think they're going to stuff more pins in there. Now, with surround sound mics, they just use a custom connector and then that goes to a fan-out cable.

6 and 7 pin are very common in my line of work. We use comm for almost every event.

As for the running power done the extra pins, some companies were doing that with DMX and blowing out DMX drives on devices not setup for power running down pins 4 and 5. Caused a lot of issues (a few lawsuits as well I think since it didn't follow the standard) and I don't think it is done anymore.

I thought ClearCom used 3-pin standard microphone XLR? My console is wired with a ClearCom station in it and it's 3-pin XLR.

What are you com system are you running that uses that many wires?

It's NOT smart to run power down a data chain interface especially when the signal is run in a true pass-thru scenario. That's just not smart. At least with MIDI, it's not a true pass-thru, it has to go through a cheap processor first(just handles the data communication, nothing more)

A friend of mine is handing me an 8-pin XLR whenever he gets the time. I gotta build some sort of power cable for a pre-amp he has. Some sort of retrofit kit to put a tube inside a U87 I think. I forget, it's been a while. I have only used my soldering iron recently to build a phantom power tester, a DMX tester, some DMX terminators and replace some batteries in some gear.

Single channel comm is 3 pin. Two channel comm needs 6/7 pin. I actually have adapters for two 3 pins into one 6 pin and back again for two channel comm. Some of our comm packs are single and some double. It allows more control too. Cameras/video only gets one channel and single channel packs. The switcher and/or switch caller gets two channels so he can hear the TD. Then other guys for production get single channel for the other line. Helps keep down cross talk and lines clear. Being lighting, I actually get a two channel pack in case video needs something from me lighting level wise.

Both Telax and Clear Comm use 6 pin and/or 3 pin. Those are the two I mainly use.

I know we're getting a bit off topic, but as far as better value, which system do you recommend?

Since I'm expanding and getting a video team and a lighting guy(I freakin' hope so), along with a monitor engineer and a 2A, I can see where you're coming from.

Lighting typically is OK on its own. Video is often fine on its own, while maybe needing to talk to lighting. Audio is basically its own little universe.

I need to get something fairly soon, say within 24 months. I'm looking to get a digital console soon and an X48, so I need to get prepared for more communication. Shouting at each other at FOH works, but I'd prefer something a bit more graceful. Of course, since right now all operations are at FOH, we can get away with this!

Well, in my experiences, Clear-Com tends to hold up better despite having plastic cases vs the metal of the the Telex. Both systems also aren't limited to two channels. You can add other channels and mix and match with more base stations. I had a 4 channel system once with one line dedicated to lighting (spot cues and lots of them), a channel for video/camera, a SM/TD channel, and a channel for audio because of the amount of mics involved/stage changes. Spots ops only had lighting channel, stage techs only had SM/TD channel, audio deck hands only had audio channel, cam ops only had video channel, and then all the leads of each group (LD, A1, A2, V1, and V2) all had the SM/TD channel to get the go from the stage when they were set and also communicate any problems. To help keep down chatter, the deck hands only gave completes when their moves were complete and spoke when there was a problem.

Both systems, however, will serve you well. I know Telex has a wireless system and I don't think Clear-Com does. However, the Telex wireless can be interfaced with the Clear-Com system. Wireless comm, however, isn't exactly the best. Clear-Com has things like lights and phones for sound guys so they don't have to wear a headset. Hitting the call button causes the light to blink and the sound guy can then pick up the phone.

Edit: Never mind, Clear-Com makes wireless now.

That's what my console is like. The talkback system has an alert/call indicator, and I can also initiate a call, then use the onboard talkback mic and headphones or nearfields for my intercom, PROVIDED I have the gear to back it up.

I've been looking into something, and my business is starting to move into a direction where I need it. I have been using my wireless in-ears for one-way communication, but sometimes I need a response back. Right now I'm training guys so I can sit at the console while they do the running for a change!

I see wireless being a very important alternative to consider but before I dive into that, I have to do an analysis of my entire wireless situation at the time. My priorities for wireless are to expand my 7 channels of wireless to 10 channels of UHF and 4 channels of VHF. This UHF means taking out 2 700Mhz units and replacing those(bringing me back to 6) and somehow being able to obtain another 4 units. After that, try to get 3 more VHF channels, which I'm already investigating. Yeah, VHF is older, but it gets me through where everyone else gets bottlenecked, especially in busy environments. Then, adding 2 channels of wireless in-ear for myself and monitor engineer, and another 2-4 for musicians. Once that is done, then I'll investigate wireless for intercomm.

At least I will use proper cabling.

I may also jump to wireless for lighting too. Probably front end that with a second OptoBranch/4 at stage and do my splits from there.

My two experiences with intercom systems were less than stellar, but I had low expectations. The first two experiences were with the junior college's theater productions, of which it was necessary for me to know the sound cues. One show had exactly 2 cues. The other had like 12. Nothing major. My other experience was using it at side of stage for a Mexican/Banda event, which was there for emergency purposes. We never needed it, but I was on it all night just in case. About the only issue that cropped up was a loose boom stand that needed to be tightened and I was on it before anyone said anything, so my director was "What the hell were you doing" and I told him "I think the mic stand was having a problem staying up". Well, that was in the days before Viagra was a common household name, as it definately needed some "mic stand viagra!", as we only needed it for 4 hours!