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Author Topic: C-lab Unitor SMPTE/EBU Synchroniser (Feb 1989)  (Read 1682 times)

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Offline chrisNova777

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C-lab Unitor SMPTE/EBU Synchroniser (Feb 1989)
« on: December 23, 2018, 12:08:50 AM »

David Mellor reviews this SMPTE/EBU timecode unit dedicated to C-Lab's Creator and Notator sequencing and scorewriting software for the Atari ST.

The era of the stand-alone SMPTE/MIDI convertor is surely drawing to a close. It's true enough that they had their uses, and will still find application for some time to come, and in certain specialised circumstances. But there is a better alternative - the integrated timecode unit. Integrated, that is, with the MIDI sequencer that it drives. Let's recap on a little SMPTE/MIDI history...


First there was the void. MIDI sequencers were but primitive lifeforms, scurrying around in their own private digital ecosystem. Then came a little light. The word became 'What if we can synchronise our MIDI sequencers to multitrack tape? We may go forth and multiply our capabilities a thousandfold'. The tape sync device became flesh.

Tape sync was a start. But the way it worked was that a tone, either FSK (frequency shift key) or of constant frequency, was recorded on one track of the tape. This contained two items of information: the start time of the track (when the tone started) and the tempo (the frequency of the tone or the FSK rate). So once you had completed the bare bones of a track on your MIDI sequencer, you would send a MIDI clock signal from the sequencer to the tape sync box, which would put the appropriate sync tone on the tape. On playback, provided you started from the top of the track every time, the sequencer would keep pace right the way through. But try starting somewhere in the middle of the track, and you would get a load of out-of-sync musical gibberish.

SMPTE/EBU timecode came as a godsend to the thousands of us who were struggling with tape sync as best we could. Timecode used to be pretty expensive stuff to get hold of - at least the machinery that could understand it was. But notable price breakthroughs - first Roland, with their SBX80 sub-£1000 SMPTE/MIDI box, then Nomad, who broke the £300 barrier - made affordable timecode a reality. The benefit was that timecode gives time-of-day information all along the tape. Convert this to MIDI Song Pointer data and the sequencer will be able to find the right place when started at any point in the track.

But now the problem: timecode doesn't contain any tempo information. The sequencer, when set to receive external sync, only knows how fast to go by the rate of MIDI clocks coming in. Therefore, the SMPTE/MIDI unit has to hold the tempo information, whether it is a continuous tempo all the way through a song, or continuous tempo changes. It also has to hold the start time information, which would be in terms of hours, minutes, seconds and frames. Having two control centres, the sequencer and the SMPTE/MIDI convertor, is at best inelegant. At worst, it is a distinct pain in the neck.

Coming up to date, we are now starting to see the arrival of sequencers with timecode capability built in. No need for separate boxes, and all tempo and start time information is held, and stored, as part of a sequence. There are not so many of them about yet, but let me name a few: Steinberg Pro24 with Timelock, Hybrid Arts SMPTE Track, Akai ASQ10. We can also add C-Lab's Creator and Notator programs to the list, for two versions of the Unitor timecode unit are now available which will give either of these programs full SMPTE/EBU capability. Let's explore...


Unitor, as you can see from the photo, is a pretty neat little gadget. Much neater than Hybrid Arts' SMPTE box, which dangles uncomfortably from two connecting leads (when I have visitors in my home studio, it's always the Hybrid Arts' box that gets the 'What is that?' comment).

What you can't tell from the photo is something that foxed me for a moment when I wanted to have a close look at the construction of Unitor - that it actually clips into place on the side of the ST. A clever bit of design which prevents the Unitor and ST becoming detached during use. Included in the package are four stick-on feet which can be positioned in two ways, to match the height of the 1040ST or the differently-shaped Mega STs. If these seem like trivial points, it has long been my opinion that if the small details are right, then the really important things will be too.

Continuing my physical description, I noted - with the aid of my abacus - that Unitor has two MIDI Ins and two MIDI Outs. With this box you can address up to 48 channels of MIDI (using the ST's MIDI Out too), with input merged together from three MIDI instruments. Who will be the first manufacturer to come up with a three-layer MIDI master keyboard? Put it on a stand with an ST shelf and mouse mat, and it will sell in millions (and don't forget to include a nice neat MIDI wiring harness and a coffee mug holder).

Completing the connector rundown are the essential SMPTE/EBU input and output jacks, and a mysterious 15-pin 'Multi-port' D connector. What is it for? The manual is silent, apart from a hint about future projects. And before I progress to matters operational, may I congratulate C-Lab for bucking the increasing trend of using black-on-black embossed lettering. Unitor's lettering is raised and outlined in light blue. Very visible.

Figure 1. Unitor's synchronisation features are controlled from the sequencer's pop-up Sync Reference window (this one is from Notator Version 2.0).


Unitor's Sync functions are controlled from the pop-up 'SMPTE/EBU Synchronisation Reference' window (accessed from Notator/Creator's Options menu). A bit of a mouthful but as long as it works...

As you can see from Figure 1, the Sync Reference window is split into several sections, plus an Exit button. Starting halfway down the window: Timecode frame rates are selectable over the usual range - 24, 25 and 30 frames per second, and also 30fps drop-frame. Below the frame rate selector is the SMPTE/EBU Generator box. This only requires a start time and a mouse click and it is away.

'Start time', normally, is the hours/minutes/seconds value at which generation will start. Here, it is called 'Offset'. Offset, as the term is conventionally known, should really mean the difference between two sources of timecode - a situation that can crop up when audio recorders are run in sync with video. Still, it's hardly likely to cause any misunderstanding in this situation.

Having set the start time, timecode generation is just a matter of plugging the timecode output signal into a tape recorder track, and off you go. If the record level isn't right (the manual includes the usual instructions on what levels to use - remember to switch off any noise reduction on the sync track), then Unitor will have to be fed through the mixing console, as with my Hybrid Arts equivalent unit.

To read timecode, you have to create a 'Sync Reference'. Start by setting the start time, the offset, and then the bar number at which you expect the song to end. Also the frame rate has to be set, if necessary, to match up with the frame rate of the timecode on tape.

Two points arise. The first is that I can't see why it matters how long the song is. It doesn't need to be set in Hybrid Arts SMPTE Track, and I can't see any advantage to it (but I bet C-Lab will be quick in pointing one out). The other is that the software cannot recognise the frame rate of the timecode coming in. SMPTE Track can, and it avoids any possible confusion. But one advantage I found here is that you can work in internal or external sync mode with Unitor without having to switch manually between the two.

Set to SMPTE synchronisation, when the pulses start to come in Unitor will drive the sequencing software. If there is no external sync, the internally generated clock pulses are used. As I found with the Akai ASQ10 sequencer (which has the same ability), it's a slight, but useful, time-saver.

While I'm on the subject of timecode reading, I found that Unitor was successful in driving the Atari ST over the full varispeed range of my multitrack (an indicated +/— 17%), a feature I had cause to use. Unitor is also very quick to sync up - even at bar 1132!


C-Lab's Creator and Notator both have a versatile tempo changing facility. Tempo can be set either in beats-per-minute (bpm) via specific commands inserted in a song, or by nudging the tempo up or down with the mouse while the song plays. Of course, this versatility has to be maintained while under timecode control.

Tempo changes have to be recorded into the Sync Reference, just as offset and frame rate were entered. This seems like a slightly awkward way of transferring information from one section of the ST's memory to another, but seeing as it is so easy to perform it is not a problem.

To record any tempo changes into the Sync Reference, you press 'Shift' and 'W' on the Atari's keyboard and run the tape supplying timecode. It happens automatically, and thereafter when you run the tape, the tempo changes will be replayed.

One feature, which beats any sequencer I have heard of so far, is the extraordinarily fine tempo resolution - down to 0.0001 bpm! To give that a little perspective, if you could start two tracks simultaneously, one running at 120 bpm, the other at 120.0001 bpm, it would take three and a half days for them to drift just one beat out of sync! Mathematical geniuses out there can check my arithmetic, I didn't put it to the test!

Practically speaking, this means that you can sync Notator or Creator to tracks recorded without the benefit of timecode - as long as the tempo is constant - by adjusting the Offset and tempo to suit the music. In fact, you could even do it if it had tempo changes - but with some difficulty. Even when the tempo is constant (I tried syncing Notator to a Stock Aitken Waterman track - a trio not known for their adventurous tempo changing), it is not a quick procedure to lock up in sync. Granted that you can make adjustments to the Offset and to the tempo while the track is running, but the recalculations necessary take quite a few seconds for the Atari to perform. Perhaps it's best to label this function 'emergency use only'.

As might be expected, the Sync Reference can be stored as part of a track. Better still, it will automatically be stored along with your MIDI data. Alternatively, it can be stored as a separate file on disk.


At the top end of the timecode synchroniser range are devices that can read code even after the tape has been through a double wash and spin dry! In other words, they can reconstruct any missing or incorrect SMPTE/EBU data and still sync up perfectly. Unitor, as timecode units go, is a low cost device. But can it still ride over the bumps, or will it grind to a halt at the first sign of trouble? The answer, thankfully, is yes it can handle small dropouts. My Hybrid Arts SMPTE Track hasn't thrown any wobblies in normal use but it didn't like it when I cut the tape to make an edit, and then changed my mind and joined it back together in the same place. It wouldn't run past the join, meaning that I couldn't add that last sequenced afterthought. Unitor, however, can handle joins and short duration dropouts - as I tested with my rusty (or was that trusty?) razor blade.


The day can't come soon enough when all sequencers have integrated timecode units such as this. If you haven't tasted the benefits of using a sequencer with built-in timecode - as opposed to one which needs an external SMPTE/MIDI box - then I can guarantee that you will find your creative life a lot easier.

C-Lab's Unitor is an excellent example of its type. It performs slightly better than my Hybrid Arts SMPTE Track equivalent, and the software is quicker to respond. (But the actual SMPTE Track program is still my personal favourite).

Unitor comes as a neat package too, together with MIDI expansion capabilities for addressing up to 48 channels. C-Lab's Notator may be the world's most expensive ST software, but Unitor fully does it justice. If you are serious about sequencing, then integrated timecode in 1989 is essential.


£349 inc VAT.

Sound Technology plc, (Contact Details).

If you currently use either Creator or Notator and want to buy Unitor, read on...

Unitor has its own built-in copy protection 'dongle'. So if you want to add Unitor to Creator, then you need to exchange your dongle (plus cash!) for a Unitor C. If you have Notator, exchange your dongle for Unitor N. As far as we know, only the dongling functions of the two units differ. Now the complex bit...

If you currently have Creator, you may upgrade to Notator plus Unitor N for only the cost of the upgrade. If you have Creator, and buy Unitor C, be aware that there is no upgrade path to Notator plus Unitor N. You would have to sell your Creator and Unitor C package, then pay the full price for Notator plus Unitor N. Still confused? Check with Sound Technology.

Both software packages have been reviewed in Sound On Sound before, NOTATOR as recently as September 1988. Briefly, CREATOR is a fully specified 64-track sequencing and editing package in its own right. NOTATOR includes CREATOR as a subset of its functions, and adds a versatile scorewriting and printing package.