LED Light Control – DMX Controllers for LED Stage Lighting

Thursday, February 14th, 2008 - LED Stage Lighting - by:

As LED technology becomes cheap, using LED stage lights is a hot topic in the world of stage lighting. The possibilities of using a low power, high brightness LED light with colour mixing capabilities seems hard to resist but how do you control your LED lights? Stage lighting controllers vary widely in both cost and features so On Stage Lighting considers cheap led light control using your existing lighting desk.

LED lighting control
Image by Tim Morgan

Are LED stage lights “intelligent”?

The term “intelligent” in stage lighting usually refers to the remote control of the lights using sophisticated systems to adjust different parameters in the fixture such as colour, gobo and effects. The intensities of the LED’s themselves are under the remote control of the lighting controller, as are any onboard effects such as strobing or colour chases that come from within the “brain” of the LED fixture itself. LED stage lights do not require the use of a normal lighting dimmer- they just need power and control signals.
So, LED stage lights fit into the “intelligent” lighting category.

Do I need a special LED lighting control?

Led stage lights are usually controlled using the DMX 512 protocol that is widespread in the entertainment industry. Any lighting controller that can output DMX will be able to control LED fixtures. The fixtures themselves have a “fixture personality” or DMX map, and this tell us which DMX channel is used for. Control channels could include: Red, Green, Blue, Amber, (some LED colour mixing fixtures have another colour, in addition to the RGB model), Effects etc.
So, you don’t need a “special” LED light control. You could use a conventional DMX lighting desk, even a manual one (a lighting control with no “scene” memory).

Like the desk I’ve already got at [insert venue here]?

Yes. Unlike more complex “intelligent” lighting kit, LED fixture personalities are fairly simple. They often use 6 DMX control channels and can be controlled on a little as 3 (1=red, 2=green, 3=blue). Using a simple lighting desk to control moving lights effectively is difficult, but controlling LED stage lights is easier and a conventional lighting desk can do it. A tiny lighting control with 6 faders could be used as an led lighting desk for 20 fixtures – provided they were all set to the same DMX start address and you don’t mind them working in sync.

Conventional stage lighting controllers mix their faders levels using Highest Takes Precendence (HTP) which is great when using colour mixing LED lights. Fade up “Blue” and add the “Red” channel and you get a genuine mix of those to colours (they give you a sort of magenta colour) that fades up and down with the control faders. Intelligent lighting controllers can use both HTP or Latest Takes Precedence (LTP) so check how the LED fixture channels are being mixed – I would choose HTP for most uses.

What is the best way to control LED stage lights?

The best way to control LED stage lighting depends on:

  • The amount of flexibility you need. Does each unit need to be individually adjustable?
  • The rest of your lighting rig. Have you got other fixtures to control such as moving lights?

If you have 96 dimmers, 20 LED battens, 10 LED PARs and 10 moving lights, you will want to use a dedicated moving light control. But, if you only need to change the colour of a few LED PARs , you don’t need a complex LED lighting controller. Make sure that you also look at what available in PC based DMX lighting control software.

Don’t forget – many LED stage lighting fixtures also have a number of programs built into them to allow colour control, static or chases, that can be used with no lighting controller at all. These are usually called “Stand Alone” mode and are great if you need to just set up your LED lights and go.

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Rob is a Lighting Designer and Moving Light Programmer and currently Senior Lecturer in Technical Theatre Production at Bath Spa University in the UK. He is also the Editor of On Stage Lighting and runs workshops in stage lighting practice.

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23 Comments

  1. Jimmy:

    Hello,

    Right bit of advice,
    Got a show comeing up, i have 6 LED Par Cans, 20 Pars and 4 Mac 250′s and a fat frog,

    I was going to do the MACs of pallets but im not sure how to run the rest of the show, weather to stick the LED’s on pallets or what knows =\

    Any suggestions for this noob?

    Thanks in advance
    Jimmy

  2. Rob:

    Hi Jimmy,

    Although not really “Fat Frog compatible” myself, I have a couple of ideas for you.

    As you say you are hoping to playback the Macs using Palettes(if the Frog lets you replay palettes live), I assume that you are going to be “busking” your show live (rather than just playing back recorded scenes).

    Submaster memories are flexible for busking. You might just record some different LED colour combinations onto some of the submaster faders and replay them.

    Alternativley, record all LED Par RED onto one sub, all GREEN and all BLUE on other subs. The using just 3 subs, you could mix your own colours live.

    If you need more LED PAR flexibility, just split your RGB colour subs to a few more faders. Don’t forget that you have more than 1 page of submasters.

    Using palettes is always a good method to organise your programming on so record some different colour pallettes for your LED PARs and fire them off during the show (again, if possible on the “old” Frog).

    Thanks for visiting.

  3. Jimmy:

    Hello, got the LED par’s the other day, i stook them in submasters but got a little issue,

    when i bring the submaster up they go up, when i drop it down, they dont. Any ideas what this could be, i gather its realy easy and im being thick but its got me stumped.

    Thanks

  4. Rob:

    Hi Jimmy,

    The answer is simple but not obvious. The result you are getting is because the sub triggers the fixtures to fade up – and that’s all. The LED’s wait for another instruction but don’t get any, bringing down the fader doesn’t send any more information.

    The reason is the fixture personality you are using with the LED Pars. Assuming that the LED don’t have an overall intensity channel (most cheaper ones don’t) then the RGB channels are being replayed on LTP (Latest Takes Precedence) basis. You can prove this by recording a submaster with LED Blue at 100% and another at 0%. Swapping between these two subs should fade your Pars up and down. Not an ideal control situation.

    The solution is to make sure you use a fixture personality that has the RGB channels set to HTP (Highest Takes Precedence – like normal dimmer control). You might feel confident enough to edit your own file.

    Another option is to patch up the DMX channels of the LED Pars as simple dimmer channels (these are always HTP) although this could use up too many control faders in your setup.

    I really must write an article on HTP vs. LTP. The choice of using LED fixtures either HTP or LTP depends on the indvidual control situation but my preference is for HTP pretty much every time.

    // UPDATE And here it is : LTP vs HTP

  5. Jimmy:

    Hey there,

    i downloaded the zero 88 fioxture editor and imported the Showtec LED’s

    I cant figure out how to change it over,

    Ever used it or anyidea of whjat it will be under?

    Thanks
    Jimmy

  6. Rob:

    Hi Jimmy,

    Not used the Frog range much but had a quick look at the manual for the fixture editor and the solution didn’t leap off the page. The virtual intensity function looks useful for this situation.

    I see that you have posted a question on the Zero88 forums and I’m sure they will have the answer. Let us know how you get on.

    Cheers

  7. Jimmy:

    Hey i posted it on blueroom, started getting a bit desperate for an answer

    Only to be realy dissapointed.
    The frog range will only do HTP on the brightness chanel, not good for my LED par’s. So i’m braking the old jands event plus out and sticking all the LED pars on there, just seems like over kill on the channels. not got enough room on the frog.

    Maybe zero88 will get back to me with a soloution

    Untill then, =/

    I’ld much rather we’ld brought a pearl, but with it being a theatre they thought a frog would be moore universal for outsiders using it.

    Cheers
    Jimmy

  8. Rob:

    Jimmy,

    That’s interesting. It’s little things like that you only find out when you come to make it work. Thanks for letting us know – everyone can benefit from your experience.

    At least the Event Plus (48?) was a nice desk. Does seem a bit much for a few LED PARs though. At least it will be flexible.

    Best of luck.

  9. Bill Cravatta:

    Our church has a very old Nova Systems NCM 6128 Light board. We desperatly need to replace it, but I don’t know where to get one that would replace this type of unit. Do we have to get a Nova unit or could we get a different brand that has 16 channels?

    Thanks.

  10. Neil:

    Hi there,

    The band I play in has recently moved from using mainly traditional par cans with dimmer packs under DMX control to LEDs. We’re using a Behringer Eurolite desk which, although not a high end piece of kit, used to work well enough with the previous set-up. I’m sure you’re familiar with the range of its functions offering “preset” real-time control and/or stored scenarios allocated to faders in memory banks.
    With the new lights preset control is fine. The lights respond exactly as one would expect to the allocated faders. However, try as we might, we cannot get the damned things to behave themselves in memory mode. Supposedly stored scenarios produce all sorts of unexpected and unhelpful results when recalled. For a start, we’ve noticed that the fader range is altered – a steady open shutter (on preset) is transposed to a flashing strobe effect. Secondly, the colours are no longer “pure” – a red scenario will have bits of some other coloured LED when recalled from memory. Finally, there is just the plain bizarre – lights doing something completely different to what they’ve been told.
    The manual is one of the worst I’ve ever come across – for even the most basic functions it may as well be written in Sanskrit so anything of this nature is totally beyond it.
    However, I suspect it’s not all down to the limits of budget gear and that we’re missing some fairly central principle within the DMX protocol. Any help would be much appreciated.

  11. Andy:

    i know how to import the fixtures on a frog desk u have to make a common fixture file. using the common fixture editor down loadable from the zero 88 support site. then when you go to the frog desk go in to super user and select Floppy Disk, then click loads CFT. This will load Your common Fixture file but beware make sure u have all the fixtures you need in this file as it will over right the stander fixture file. you can go back to the stander fixture file at any time my down loading the latest software off the zero 88 site.

  12. Rob:

    @ Neil

    Sorry to hear that you are having problems with your new LED PARS and Behringer Eurolight. I had a look at the manual and i didn’t really find what I needed.

    I don’t have any direct experience with the controller (anything that is called a “light mixing desk” is not for me).

    There is a thread on the Blue Room about the LC2412 which might throw some light on your problem. The BR also has a good selection of posters who have experience in this level of equipment. Sorry we couldn’t help this time.

  13. Nick:

    Hey,

    Our school is putting on CABARET as our musical for the year and we have purchased 4 led pars to use along with our conventional lighting system to get color mixing capabilities on some of the set.
    We were going to get a small dmx board to control them but someone suggested that we can run them through our current board.
    We have and ETC express 125,
    any direction as to how we would patch and hook this up?
    and then how it would run?
    thanks,
    Nick

  14. Rob:

    Hi Nick

    Setting up your LED fixtures with the ETC Express is probably easiest if you patch the LED DMX channels as dimmers as suggested here. You need to know:
    How many spare channels you have on the desk.
    How many DMX channels the LED fixtures use.
    Which channels you need to adjust for Red, Green, Blue and possible the Dimmer Channel.

    The ETC console has a playback stack and submasters but for CABARET, I assume that you will record your scenes in a stack of memories and the replay them during the show. When recording your scenes, just add in the LED fixtures where you need them and save them with the other dimmer settings.

  15. Matt:

    I am looking at getting hold of a Zero88 Fat Frog desk quite soon and some of the team want to introduce some LED Fixtures to our arsenal. Can anyone tell me if the LED fixtures will go on my normal dimmers or are they controlled from the part of the desk that is used for intelligent lights? It’s important because we want to get some MAC250s in the near future and the Fat Frog only runs 12 intelligent lights – if LEDs and MACs all count as intelligent then we need a bigger lighting console.

    Thanks

    Matt

  16. Rob Sayer:

    Matt – You can use the Frog “dimmer” channels (faders – not actual dimmers) to control LED fixtures but remember that each LED unit uses at least 3 dmx channels so can use up faders.

    You could alternatively use the intelligent fixture controls (as you say, up to twelve different DMX start addresses).

    Either way, don’t forget that you can save faders or fixtures by setting multiple LED units to the same DMX start address and controlling them in unison. Just work out which ones you can “pair up” and still have an acceptable level of control flexibility. Using this method, you could control all your dimmers, 6 Mac250s and still have 6 ways of LED control with an whole load of LED fixtures connected.

  17. Matt:

    As usual – very helpful. Have to admit I’d have been lost with out OSL over the past few months! Don’t suppose you know if IPA will do any harm if I clean a greasy projector lens with it?!

    Matt

  18. Owen:

    In reference to all those with Frogs – I’ve found the easiest way to control large numbers of LED ParCans or similar is to create your own fixture profiles using their Fixture Editor. This allows you to do all kinds of weird stuff, such as controlling 4 fixtures from one fixture on the board. Not ideal, but saves lots of faders.

  19. Martin:

    Hi,
    I’m a newbie in stagelighting. But our band (7) want to buy our own lighting kit, so that we only had to rent some special fixtures if needed. As a start we thought about 16 par64 cans LED, mounted on 4 tripods with t-bars. The question is about controlling them. We thought about a cheap Stairville dmx-master I (http://www.thomann.de/gb/stairville_dmxmaster_i.htm), which is acutally made to controll moving lights. It can controll 12 fixtures with 16 dmx-channels each. Do you think it’s worth trying this controller for a start? Another problem I see is, that it doesn’t have any main sliders. Probably I just should order it and give it a try…
    Thanks in advance for any information you have,
    Martin

  20. Matt:

    Hi Martin,

    It sounds like that controller would be great for your purposes. If it controllers 12 fixtures and you are buying 16 then you will need to pair some of your LED PAR64s but then that’s fairly normal anyway. To pair them up just set the DMX start addresses as the same for two fixtures. It’s worth noting, before you buy your DMX cables that the article you’ve linked to seems to imply that the output is 3 pin DMX and not the standard five pin. It’s worth checking what your LED units have too – if they are all 3 pin then you obviously don’t want to buy 5 pin cables. If you find that you have a mix of 5 pin and 3 pin then you need to find some converters (they’re very cheap) – I’d recommend tails rather than barrels if you have the choice – the barrels tend to be quite fragile.

    Good luck with it all!

    Matt

  21. Martin:

    Cheers, Matt. If you or anybody else have other suggestions, please let me know. Thanks in advance, Martin

  22. Matt:

    Don’t forget you can use most LED PAR units in stand alone mode and you wouldn’t need a desk then. Might be worth looking at that first – you might save a lot of money. You could also look at PC based control with a USB/DMX dongle – I’ve never used it and lots of people don’t like the reliability issues associated with that but you never know – might be worth looking at

    Matt

    »crosslinked«

  23. David:

    Up until now, I have played my own music shows using 40 par 56s and six scans. I ran my lighting control from 40 MIDI triggered 300w dimmers allowing me to perform with a cheap but sophisticated looking light show in complete syncronisation to the music.
    Wishing to update, I have just purchased 6 LED stage floods, each with 24 3w LEDs. These have several DMX settings, the largest being 27ch (24 individual faders for the LEDs, 1 master fader, 1 strobe and one internal program selector).
    My problem is finding a desk (with MIDI) which will allow me a minimum of 114 channels of DMX (4@15ch 2@27ch) to be recalled with some form of HTP crossfade facility. I am currently trying a unit which offers 480ch of DMX and many functions – offering individual control of up to 20 heads, but it does not seem to have this basic function as an option even though I can label each fader as a “Dimmer”.

    Surely there must be a desk out there which can handle my needs without costing thousands. Does anyone have any ideas or suggestions?

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