Clef CMS - Synthesiser for the BBC Micro

 

This was my first synthesiser. It seems now to have all but disappeared from history, so I thought I'd put together some info on it while it still works.

Clef Electronic Music produced various music technology products back in the early 1980s, including the B30 synthesiser and a drum machine.

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Another of their products was the Clef CMS, a synthesiser designed for use with the BBC Micro. It was available in two versions, one smartly finished and one in a more basic DIY form.

(That black panel was my own addition - as you can see, I didn't get very far with the DIY part.)

Richard Hodges, who worked for the company, writes:


"I wasn't involved in the design though I did spend ages working to improve the factory sounds...whether you got mine or the original ones depends on when it was purchased. I remember getting a metallic clock chime sound that I was quite pleased with as the Yamaha DX7 had just come out and was setting the standard with those metallic sounds. The idea behind the CMS was 32 oscillators that existed in software only (the designer, Alan Boothman, called them 'virtual' oscillators) and we were driving the circuitry very hard to achieve this, such that some of the chips specified had to be rejected as they weren't fast enough despite being supposedly identical.

Even double sided PCBs were quite new then and we had trouble with the plated through holes and had to put pins in some of them! Also, the ribbon cable between the CMS and computer couldn't be longer than a couple of feet or the data transfer would glitch. We really were thrashing the available technology to get the results we wanted and it was exciting to work there."


The software to drive the system was supplied on a 5.25in floppy.




It had two jack sockets for audio out, plus a DIN socket for a sustain pedal. It was connected to the BBC Micro via a ribbon cable to the 1MHz bus.

I could hardly play the keyboard, but my brother recorded various tracks into the sequencer from a Louis Armstrong songbook. Here's an MP3 of "How come you do me like you do"...

How Come You Do Me Like You Do

...and here's a bit of Yazoo. I can't remember where this came from - perhaps it was a preset demo.

Yazoo


Ben Glover
29/10/13