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C-Lab Unitor 2

Atari ST SMPTE Synchroniser/MIDI Interface

Synchronisation made easy - for Creator/Notator users, at least. Tim Goodyer locks into C-Lab's integrated SMPTE synchroniser and MIDI expander for the Atari ST.

Synchronisation is never the easiest of matters to deal with, but users of Creator/Notator sequencers have it easier than most if they adopt C-Lab's own SMPTE synchroniser.

You're using C-LAB'S Creator sequencer or Notator scorewriting program and you're looking to move into the big boys' world of SMPTE (Society of Motion Picture and Television Engineers) synchronisation. The problem is that you're not sure which synchroniser to go for. You want something that will do the job, sure, but you want it to integrate well with the software you're using. On top of that, you've seen that the current batch of Macintosh synchronisers seem to offer all sorts of "extras", like additional MIDI ports and patchbays. Where are the equivalent units for the poor ole ST? Are you being left behind by progress?

For once you can relax. Not only have C-Lab's boffins largely anticipated your need, but the unit you're searching for has been available for years - longer than the Mac boxes you were worrying about. Not only that, but you actually already have the software you need embedded within Creator or Notator. Unitor, as C-Lab have christened their synchroniser, has recently been superseded by Unitor 2. And that's where this review comes in...

Briefly, then, Unitor 2 is a SMPTE/EBU synchroniser and MIDI interface expander. Sorry, no patchbay.

Unitor 2 - as it comes out of its cloth carrying case - is a black plastic box (roughly 8" x 3.5") which takes the place of the Creator/Notator dongle in the Atari's ROM Port. The dongle then fits into a similar port on the front of Unitor. This is the only visible difference between this version of the unit and its predecessors - previously there were two versions, Unitor C and Unitor N, and the appropriate one of these took the place of your dongle. No, this didn't mean you ended up with two dongles (and therefore the opportunity to sell on a copy of the program with the dongle you no longer needed) as the dongle was part of the "price" of Unitor. The new arrangement is more logical but leaves you with two pieces of hardware to lose instead of one. Classic swings-and-roundabouts stuff.

Along the left-hand (outside) edge of Unitor there are two MIDI In sockets (marked In I and In II) which function in addition to the Atari's In, two MIDI Outs (Out E and Out F) which function in addition to the Atari's Out, a 15-pin D-connector (marked Multi-port) and quarter-inch jack sockets for SMPTE In and Out.


The additional MIDI Ins and Outs operate simply enough. When assigning instruments within a Creator/Notator Pattern, you now have the option of using MIDI Outs E and F, effectively giving you access to a total of 48 MIDI channels. The missing Outs C, D and E (the Atari's own Out being designated the A port) are to be found on C-Lab's Export unit. Unitor's MIDI Ins can be merged together with the Atari's In and filtered and submitted to Creator/Notator's realtime Transform functions if required.

The D-connector is for use with other C-Lab peripherals, Human Touch and Steady Eye, which allow manual timing input and phase-synchronous operation with video respectively. The SMPTE jacks connect directly to your multitrack and are set up to output at -6dBm and accept input levels between -20dBm and +6dBm. The manual gives guidelines on setting levels for 2" and 1" machines, ½" and ¼" machines and cassette multitracks. It's reassuring to know that Unitor hasn't been aimed at professional users to the exclusion of those with more modest studios.

So much for the hardware. To operate Unitor you'll need to open the Synchronisation window under the Options menu (or hit S on the Atari's keyboard). Here you'll find all the setup facilities you need - and in a more convenient layout than you'll find on a standalone hardware unit. All four frame rates are available (24, 25, 30 and 30 Drop Frame). For use with European TV standards you won't need to change the default setting of 25 frames per second, but if you're moving into the film industry you'll need to use 24fps.


Before you can actually get on with the business of putting code to tape, you'll need to create a Sync Reference within Creator/Notator from your sequence. This is performed within the SMPTE Sync window. If you're dealing with a constant tempo or you've contained your tempo changes to a single tempo track, this is as simple as selecting a Track number (this needs to be the tempo track if applicable) and clicking on Create. You can name this reference if you wish, otherwise the word "Created" appears in the Reference box.

You can set a SMPTE Start Time for Unitor - this tells Unitor's clock what time to begin running from. The default setting is 00:59:55:00 (00 hours: 59 minutes: 55 seconds: 00 frames) and there shouldn't ordinarily be any need for you to set it up differently. Finally you need to set a SMPTE Offset in the appropriate box. This tells Creator/Notator how long after the start of the timecode it should begin to play. Any arbitrary offset is adequate - the manual suggests 20 seconds. Now you can go to tape.

A few words of warning: you should try to keep the signal path between Unitor and your multitrack as "clean" as possible, as any alteration of the timecode is likely to make it less reliable. Worst offenders in this area are noise-reduction systems (especially dbx) and EQ. In keeping with industry practice, Creator/Notator's manual advises you to stripe code onto the highest-numbered track of your multitrack. Although this does make it more susceptible to tape "edge damage", it minimises spilling of the code onto adjacent (audio) tracks. The manual also directs you to put the code down without the sequence running - which you do by running the tape and clicking on Start. The SMPTE code should run for some period over the length of the piece of music; stopping the sequencer is taken care of as part of Creator/Notator's Arrange function.

To run Creator/Notator under control of the multitrack, you must exit from the Synchronisation window and put the software into SMPTE mode - by pressing Y on the Atari keyboard. Now, running the tape from the top will cause the sequencer to run until the Arrangement tells it to stop. What's most valuable about SMPTE, however, is that you can also run the tape from anywhere within the length of the code and the sequencer will pick up the correct position almost instantaneously. If you're using MIDI timecode without Song Position Pointer, you'll need to run the tape from the top each time otherwise any music on tape will run from your start point but the sequencer will start from the top regardless.

Back in the Synchronisation window, you can choose to have the sequencer run from some point other than the default of the start of Bar 1 if required, by entering an alternative position into the Song Start Box. Similarly, the default setting of Bar 201 for Song End can be altered to stop the sequencer before the stop point in the Arrange mode or if you want to run the same Pattern until your Song End marker.


Deriving a Sync Reference from a single Creator/Notator Pattern is the simplest way of doing the job, but Unitor offers other options for dealing with other problems. Learn SMPTE/Internal (under the Options menu) will construct a Sync Reference from a Creator/Notator Song when there are tempo changes contained in different Tracks. Learn SMPTE/MIDI (also under the Options menu) allows you to play SMPTE code and MIDI tempo information into Unitor simultaneously. Unitor is capable of building a Sync Reference from a copy of both sets of information. You might need to resort to this if you have already recorded SMPTE code from another SMPTE sync unit, but wish to lock Creator/Notator to it using Unitor.

Sync References, once created, can be edited. Creator/Notator's manual is pretty helpful on this one, giving a guide to how a Reference may be constructed for music already on tape without timecode and whose tempo is unknown. Generally, this sort of editing is going to be pretty tricky and is best avoided if possible. If you've ever edited a tempo track, you'll have some idea of the potential problems.

Once you have created a suitable Sync Reference, you can save it as part of a Creator/Notator Song file so that it will automatically be loaded into the sequencer with the rest of the sequence data or you can save it as a separate .REF file.


When you first start to use Unitor, it's hard to believe that you're actually dealing with something as complex as SMPTE timecode - Creator/Notator's software makes operation that simple. In contrast with most software capable of doing a useful job, the learning curve is both short and shallow.

The main advantages offered by Unitor to Creator/Notator users are that the degree of integration between sequencer and synchroniser is far higher than that of most hardware synchroniser/sequencer pairings. As an example of this, the display on Creator/Notator's main page gives an indication of the security of the SMPTE code coming off tape. If there's no display in the box, the code is good; poor code is indicated by a bar-graph which reads higher for greater errors. In case of serious discontinuity in the code, an error message appears on screen.

Another useful addition to the software is the Fit Time Calculator. This takes some of the hard work out of the maths when calculating tempi to fit time windows and so on. It also allows you to directly transfer the tempo resulting from a calculation to the tempo window in Creator/Notator.

It's strange that in a review of Unitor, almost all of the attention should be directed towards software that isn't part of the unit itself - yet this accurately reflects both the level of integration of the unit into C-Lab's studio system and the price of the hardware unit, as measured against other professional SMPTE synchronisers. Then there are the extra MIDI Ins and Outs to take into account...

Of course, you might suspect that, in the interests of developing an all-in-one approach to MIDI sequencing and synchronisation, C-Lab had sacrificed the standard of one or other of the individual functions. Well, let's just say that I know of one development company working in high-level DSP technology for the pro-audio industry who currently use Creator and Unitor purely as a source of SMPTE code - because it's the best they've found.

Price £390 including VAT.

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


Music Technology - Mar 1992


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Synchroniser > C-Lab > Unitor 2

Review by Tim Goodyer

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