View Poll Results: 3-Pin or 5-Pin DMX Connector

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  • 3-Pin

    14 82.35%
  • 5-Pin

    3 17.65%
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Thread: DMX, 3pin or 5pin connector?

  1. #1
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    Default DMX, 3pin or 5pin connector?

    So, what do you folks use most? 3pin or 5pin DMX connectors?

    Thanks!

  2. #2
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    Most of the lighting I work has both 3 & 5 pin DMX connections, with just the higher end stuff having only 5 pin. As for the cable itself, I don't think I even have 5 pin cable, just a few 3-to-5 pin adapters.

  3. #3
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    No doubt 3 pin. As Stiffler said, it's mostly some higher end gear that uses 5 pin and I always have to keep adapters handy (that are hard to find locally in stores). The Entec boxes use 5 pin. My Behringer lighting board uses 5 pin and one of my Mobolasers only accepts 5 pin. My other one was modified to take 3 pin. Every other piece of gear I own and the majority of what I've seen uses 3 pin. I guess if you're running sharpys or other $10,000 moving heads then you're probably finding 5 pin. Stumbing across 5 pin on something is always a pain in the ass.

  4. #4
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    5 Pin.
    It keeps people from doing things like accidentally plugging the lighting system into the audio system.
    also: Microphone Cable != DMX Cable

  5. #5
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    I use 3 pin with adapters where needed.
    For jobs using less than 20 fixtures on a regular size stage mic cable works just fine.
    I used to only carry DMX cable and use it for sound too, as it's better than mic cable.
    Very few 5 pin cables actually use 2 twisted pair cable as so few systems actually use the other 2 pins
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  6. #6
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    Thanks for the feedback everyone!

  7. #7
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    5 Pin XLR is the USITT 1990 standard for DMX signals, and although a lot of people use 3 pin due to it being cheaper, the mic grade cable most commonly used does not have a twisted pair, its impedance is different than what is needed for proper RS422 signal spec, shielding is not as adequate, and it can be confused for other types of signals (audio, power, etc) that also use 3pin XLR.
    If you want to be completely compliant to both the electrical standard and the spec that designed DMX512, 5pin is the only way to go.

  8. #8
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    Quote Originally Posted by Bradfo69 View Post
    No doubt 3 pin. As Stiffler said, it's mostly some higher end gear that uses 5 pin and I always have to keep adapters handy (that are hard to find locally in stores). The Entec boxes use 5 pin. My Behringer lighting board uses 5 pin and one of my Mobolasers only accepts 5 pin. My other one was modified to take 3 pin. Every other piece of gear I own and the majority of what I've seen uses 3 pin. I guess if you're running sharpys or other $10,000 moving heads then you're probably finding 5 pin. Stumbing across 5 pin on something is always a pain in the ass.
    +1

    All my "consumer" grade DMX fixtures (some of which are NOT cheap!) use 3-pin XLR connections.
    I've had some pretty crazy cable runs for some of the DMX effects I've used in my holiday shows, but as long as I use DMX-rated cables and a DMX terminator at the end of the chain, I have never had any problems.

    One of the notable exceptions to the 3-pin XLR connections on the gear commonly used by folks here is the Enttec DMX USB Pro interface, which is the default interface supported by the Pangolin software (Beyond & QS2). That interface (and probably some others) uses a 5-pin connection, but as Brad mentioned, adapters are available to handle the 5-pin to 3-pin conversion. I've never had any problems using the Enttec interface with an adapter attached to the interface, and 3-pin DMX cables for everything else.

    In the USA and for the group that is most likely to participate on this forum, 3-pin DMX XLR connections are probably going to give you and your mystery project the greatest opportunity for hassle-free connectivity...
    Last edited by Stuka; 07-11-2014 at 04:10.
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  9. #9
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    5pin XLR is the standard spec, not the exception!!!! But unfortunately too many manufacturers are lazy and now we have so much 3pin it's becoming commonplace.

    To be more specific, the big issue is using cheap mic cable for DMX signal.
    Audio is low frequency / low speed signal. Mainly sinusodial waveforms. DMX512 runs at 250kb/s which roughly equates 125kHz i e about 5 times higher than the highest audio frequencies. The digital signal is made up from 1's and 0's with sharp transitions in between each bit.
    Using a cable designed for this purpose increases the chances of problem free transmission quite a lot. Cables designed for DMX512 have much lower capacitance than mic cable. The capacitance 'slows down' the sharp transitions from between bits and makes it harder for the receiver circuits to discern between 1's and 0's.
    The capacitance is per metre so long cables is a bigger problem than short ones. On a more technical level, each cable has a characteristic impedance. For DMX512 it should be 120 ohms. This is a non-issue for audio use but at DMX512 speed it does matter.
    To a pulse, traveling down that cable, a 120 ohm resistor looks like the wire goes on forever. A major change in the impedance, on the other hand, looks like a brick wall. The pulse hits it and bounces back... and it doesn't stop at one bounce. The output driver in your controller has a much lower impedance than 120 ohms in order to drive strong-enough signals down the cable, so once again the pulse bounces, only this time it may be turned upside-down. As the bounce passes each receiver it either adds to or subtracts from the voltage that receiver sees from the orignial pulse. It can actually turn a 1 to a 0 or a 0 to a 1.

    THIS is why people need to adhere to a control system spec!

    Back to the 3pin vs 5pin issue, here’s one nugget to ponder: Would you buy a projector that had a DB15 connector instead of DB25? The issue here is standards, and I think we as responsible people should adhere to them to maintain safety and reliability.

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