Home -> Magazines -> Issues -> Articles in this issue -> View
C-Lab Unitor 2 | |
Atari ST SMPTE Synchroniser/MIDI InterfaceArticle from Music Technology, March 1992 | |
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.

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.
More from Sound Technology pic, (Contact Details).
Back On Top? - C-Lab Notator/Creator V3.1
(SOS Mar 92)
C-Lab Creator
(SOS Nov 87)
C-Lab Creator - Software for the Atari ST
(MT Dec 87)
C-Lab Creator
(MIC Jun 89)
C-Lab Creator/Notator V3 - Atari ST Software
(MT Mar 91)
C-Lab Human Touch
(SOS Nov 89)
C-Lab Notator
(SOS Sep 88)
C-Lab Notator 3.0 (Part 2)
(SOS May 91)
C-Lab Notator V3.0 (Part 1)
(SOS Apr 91)
C-Lab Unitor - SMPTE/EBU Synchroniser
(SOS Feb 89)
Browse category: Software: Sequencer/DAW > C-Lab
Browse category: Synchroniser > C-Lab
Gear in this article:
Review by Tim Goodyer
mu:zines is the result of thousands of hours of effort, and will require many thousands more going forward to reach our goals of getting all this content online.
If you value this resource, you can support this project - it really helps!
New issues that have been donated or scanned for us this month.
All donations and support are gratefully appreciated - thank you.
Do you have any of these magazine issues?
If so, and you can donate, lend or scan them to help complete our archive, please get in touch via the Contribute page - thanks!