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Groove MC-Lite

MIDI-controlled Stage Lights

Extending MIDI control to cover stage lighting is a logical extension of a system which can already control most aspects of music. Vic Leonard strikes a lite.

Once MIDI had spread its sphere of control beyond simply slaving one keyboard to another, it was really only a matter of time before it took over the light show...

LIGHT: THE FINAL MIDI frontier, to borrow an expression from a well-known TV series. Seriously though, how useful would it be to be able to dedicate a MIDI sequencer channel to the control of a light show for live work? Think about it - it could signal an end to missed cues and forgotten lighting sequences, and as "live work" covers everything from raves to the theatre, the applications are broad indeed. A further advantage would be that of not needing an additional person behind a lighting desk - good news if you're trying to keep costs down, excellent news if you have trouble finding the right person for the job...

Groove Electronics, already well known for their MIDI retrofit work, have released the MC-Lite system. Not only does it offer MIDI control of a light rig, it does it for less than the price of your average multitimbral expander.


MC-LITE CONSISTS of a 16-channel, micro-processor based light controller, complete with an eight-channel power pack built into a single case. By using a separate, optional power pack, all 16 channels of lighting can be accessed, with the banks of lights for each power pack having an independent MIDI channel. The switching on and off of the bulbs is controlled, not their actual brightness, although various other aspects such as rate of pulsing and decay time can be controlled. Up to 500W per channel is available as standard and optional extras include 1KW per channel and pin-spot/inductive loads.

The main MC-Lite unit is a 2U-high rackmount affair with a pair of handles on the front for ease of installation. The front panel has three sections; eight buttons and LEDs for selection of Mode, Parameter and Value; eight LEDs to show which lights are currently on and off; a Pre-heat amount rotary which keeps the filament of a bulb partially lit when not in use (to increase lifespan and improve response time).

The rear of the unit has two MIDI Ins, marked A and B; the light control information is taken from In A while MIDI Clock, used to send a pulse signal to the lights, is accepted at B. There are also MIDI Out and Thru sockets, although they both appear to act as Thrus, and two LCSI (Light Control Serial Interface - a Groove invention) sockets; Out B for sending controller information to the external power pack for the other eight channels, and Thru A for slaving further power packs from the internal eight channels, so doubling up light banks. Unfortunately, Groove have decided to use five-pin DIN sockets for these connections, into which MIDI plugs fit. No matter how many warnings there are within the manual, in semi-darkness and with a racked unit, mistakes are bound to occur, and as the pins in use are numbers 2, 4 and 5, the same as for MIDI, errors are likely to be expensive. The cost-saving reasons behind this decision - both for Groove and someone using MC-Lite - are understandable, but I really feel that this has to be changed.

The output to the lighting bank is in the form of a ten-pin Bulgin socket. A heavy-duty mains switch, fuse and non-detachable mains lead complete the guided tour although, personally, I would have preferred to have seen a removable mains lead in the interests of safety - permanently attached ones tend to get easily twisted and damaged.


MC-LITE DOESN'T HAVE a screen so all edits have to be made by the buttons on the front panel with help from their associated LEDs. An LED can be on, off or flashing either slow or fast to indicate which of a number of selections is currently active. Labelled A-H from left to right, A (yellow) LED is used to select one of the 16 Performances (in which the values of all parameters are held), or one of the three edit options. LEDs B, C and D (green) select a parameter to edit, and the current mode is shown via C and D. LEDs E, F, G and H (red) are used to set and show the value of a parameter in a binary fashion, so allowing for values 0-15. It's a bit of a fiddly system to use, but it's effective and a lot better than a non-backlit LCD.


THE SIMPLEST WAY to use MC-Lite is to replay one of the 16 preset light sequences from the unit's Sequ mode. These each have 16 steps and can be run from the internal clock, in which case button C acts as a start/stop switch while E, F, G and H select the preset and are also used to control the rate of the internal clock. As the clock is unlikely to be in time with your music, you can change from internal to external sync and import MIDI Clock information from a sequencer (including MIDI Start and Stop commands). As 24 MIDI Clocks are sent per quarter note, there is a parameter (Seq Ext) for setting how many Clocks need to be received before a sequence moves to the next step. Setting up a light show by using this function will take you less than five minutes, but the results are somewhat boring, so let's move on.


THE MC-LITE'S TRIG mode allows you to assign a MIDI Note number to each light. This uses a Keymap, for which there are four options: the User option allows each light to be set to any MIDI Note.

Base facilitates the setting of a Base Note; the lights are then controlled by this and the seven consecutive MIDI Notes. The Frequency option divides the MIDI key range into eight regions of 16 Notes each; each region then controls one light. Under the Binary setting, one of the 16 patterns from the current sequence is assigned to each MIDI Key, creating a repetitive, 16-note loop.

The User option would be used when you are keying in MIDI Note information specifically for the light show, and Base would be well suited to use with a sequenced line, perhaps on a synth bass. The Frequency and Binary setting, meanwhile, allow you to incorporate an interesting light show into a live performance without needing to create a special sequencer track.

While the brightness of the lights is beyond the control of MC-Lite, the gate time - the length of time the lights stay on - isn't. Here again, MC-Lite offers you four options. The first of these is Fix Gate; here each light stays on for a time which you can set between 100 milliseconds and two seconds. The second, Velocity Gate, allows the lights to stay on for a time proportional to the velocity of the MIDI Note. Key Follow, meanwhile, permits lights to be turned on with a Note On command and switched off when the relevant Note Off is received. Using Hold Gate the lights stay on until the next step in a sequence is received.

As the Controller can effectively handle two power packs, each with eight lights, the Keymap and MIDI channel can be set differently for each of the two banks. However, the same Gate Mode holds for both packs although the Gate Time can be independently set.

"On the creative side, you don't have to run MC-Lite via a sequencer; a connected MIDI keyboard would do the job just as well."

There are two other uses for incoming MIDI Notes. Instead of the rate of the sequence steps being controlled by either internal or MIDI clock, you can also control it with MIDI Notes via the unit's Tseq Mode. Any MIDI note received which is included in the current Keymap moves the selected sequence onto the next step.

There is also Meter Mode where the bank of lights acts as a bar meter, showing the average velocity value of the incoming MIDI Note data on the currently selected MIDI channel. One of 16 levels of decay time for the lights can be set, with the fastest giving the best response.


THERE IS PROVISION for the MC-Lite to reverse the direction of a sequence of lights. This would be used in the Meter and Sequence modes. You can also limit the maximum number of bulbs which can be lit at one time - pretty essential if you're using eight 500W bulbs off a 13 amp ring main.

On the MIDI side, MC-Lite responds to MIDI Patch Change commands on the MIDI channel set for either of the two power packs. Program changes 1-16 select the preset sequence of that number, as expected. Groove have extended this application to include the selection of the mode (Trig, Sequ, Meter and Tseq) by Program changes 17-20, while Program change 29 changes the current state of the Direction. It's a sound idea, as you have a lot more control over the light show through these commands.

One final extra is the use of the second MIDI In port. If you're using MC-Lite in either Trig or Meter modes, MIDI Clock received at MIDI In port B modulates, or pulses, the lights while they are switched on. The rate of modulation is set by the value of the Seq Ext parameter mentioned above.

Groove also make the 12-channel MIDI Gate which accepts MIDI Notes and sends out a voltage between 0v-10v depending on the velocity of the note. However, the output from this unit is via an eight-pin DIN socket, which is intended for current light-dimmer packs and is incompatible with the MC-Lite. Consequently, there appears to be no way to make MC-Lite control the brightness of the attached lights.


MC-LITE MUST BE viewed in the context for which it is intended - a live setup. In the case of popular music (whether it's pomp rock or hip hop), there's plenty of scope for creating a light show which will accentuate the dynamics of the music - in fact, the control is more than I would expect from a "cheapish" device like this. If you want to be lazy, simply use the preset sequences. If you want to embellish your set with a light show which would happily grace a major rock band, the potential is there - it really is up to you.

But there's no reason to restrict the use of MC-Lite to a conventional "band" setup. The facilities are equally applicable to many different forms of audio/visual entertainment - modern dance perhaps, theatrical productions... Further applications for a MIDI-controlled lighting System will certainly not escape solo performers already using sequencers - whether you're an aspiring Adamski or trapped on the social club circuit, a perfectly-synced lightshow that comes without the expense of an operator has got to be worth checking out.

On the creative side, you don't have to run MC-Lite via a sequencer; a connected MIDI keyboard would do the job just as well, especially with the various Keymap options. Using the Binary mode, you could happily finger your way around the keyboard and manually trigger through the 16 steps for a particular sequence. When you (or your audience) get bored of that, you could either select another sequence or else run MC-Lite on its internal clock. In fact, there's an optional footswitch which can be fitted and will control various of the functions.

Apart from my strong reservations concerning the LCSI sockets, MC-Lite does what is claimed for it, and in a very usable manner. All you really need now is a sense of adventure and a spare MIDI channel.

Prices MC-Lite, £325; Extra Power Pack, £175; Inductive Load, £50; lkW per channel, £50; MIDI-Gate, £285. All prices exclude VAT.

More from Groove Electronics, (Contact Details).

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Designing The Future

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Roland Tentrax

Music Technology - Copyright: Music Maker Publications (UK), Future Publishing.


Music Technology - Aug 1991

Review by Vic Lennard

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> Designing The Future

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> Roland Tentrax

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