Clef B30 Microsynth

The first kit synthesiser that I built myself was the Clef B30 Microsynth synthesiser. It was featured in the magazine Practical Electronics. I regularly had this magazine so when I picked up my copy in the newsagent to see this synth on the front page you can guess I was more than a little excited!

Like all synths in magazines it was to be featured in parts but this was not going to drag on for months this was just in two parts! That meant it was going to be quite straight forward to build! Upon further investigation after getting home my excitement was heightened to see that the circuitry was quite simple and almost all of it was on one circuit board.

The kit in 1982 was £129, which to me was almost affordable! Not only that but nearly all the switches and controls were all mounted on the same PCB so that meant hardly and wiring compared to other kit synths that seemed to contain miles of the stuff! I knew I had to build one and although the PCB for the synthesiser was far bigger than anything I had every built before it was quite straight forward to construct. Upon competition I wasn’t disappointed, it was the first synthesiser I had ever owned and it’s probably fair to say that I was obsessed with my new toy for quite a few weeks!

To keep the cost and size down some of the controls from the modules had been cut down somewhat but this was still a versatile machine for its size and price, one of the strangest things about this instrument was the fact that it didn’t adhere to the 1 volt per octave standard that many other synthesisers of the time did. The B30 used a third of a volt per octave and it also had a linear relationship to voltage as opposed to the more usual logarithmic one, this meant interfacing with other synthesisers and sequencers could be quite a challenge to say the least.

The Clef B30 had two voltage controlled oscillators, although VCO 1 could only produce square and pulse waves, the pulse width could be modulated. VCO 2 could produce all the usual waveforms which was useful as it could also be switched to low frequency mode to become an oscillator.

It also had a noise generator and an attack/release envelope generator that had to be shared between the filter and the VCA. The top of the front panel featured the control potentiometers while the bottom half contained all the switches, of which there were quite a few which gave the instrument quite a few different options for sounds. Even though some of the modules were slightly limited by their cut down controls this was essentially a two oscillator monosynth where as some of the immediate competition for it were only able to offer one.