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Tim Stinchcombe's Synth Stuff


How I got into analogue synths

As a youngster in the early 1970s I was both interested in electronics and endlessly fascinated by the wondrous new machines, synthesizers, that were emerging at the time. I would spend hours reading the manufacturer's brochures, trying to work out what all the technical terms meant, and dream of being able to afford to build the Practical Electronics Sound Synthesizer.

In 1976 I set out for college with the intention of studying electronics, but within weeks I became disillusioned with both what an electronics engineering degree was going to be all about, and also the approach of the engineering lecturers, and on finding mathematics much more to my liking in both respects, quickly switched my registration to maths instead. Thus for over 20 years since the late seventies I barely gave either electronics or synthesizers another thought.

That changed in 2001 not long after I finished my PhD, gained during a second bout at college. I was working in a radio comms research department, and one day I stumbled across a phase-locked loop, a component part of which is of course a VCO, a voltage-controlled oscillator. Recalling that VCOs were also to be found in synthesizers, I realised I probably now had the wherewithal to understand what VCOs were all about. Under the promise of reading all about those knob-covered devices I dreamt of as a kid, I purchased a copy of Mark Vail's excellent book, Vintage Synthesizers, and to my utter astonishment discovered that you could still buy an analogue, modular synthesizer (I had assumed by now that everything would be digital), and I was also pleased to discover that EMIS, at the time the UK distributor for Doepfer, was only about an hour down the road in Bristol. It thus wasn't long before I had travelled down there and returned with a G6 case stuffed full of modules, with which I had a good deal of fun, making the fabulous noises that I had dreamt of as a kid.

Endeavours culminating in a life-impacting change

One evening I was really struggling to understand what on earth the Doepfer A-136 Distortion/Waveshaper module was doing—being a newcomer to synths I had no experience to draw on, and I didn't find the explanation in the manual that illuminating. On looking at the small PCB it occurred to me that I did know some electronics—after all I had passed my first year engineering course—and seeing that it had op amp chips on it, of which I knew absolutely nothing other than the fact that their use was widespread in analogue electronics, I thought perhaps I should have a go at working out what the module was doing. I bought a book from Amazon that told me what op amps were good for, and I sat down and traced-out the circuit—i.e. I reverse-engineered it. After many hours across a few evenings I finally had the complete circuit in front of me: the book explained what the specific op amp configurations did, and I was finally able to piece together exactly how the module worked.

This completely reinvigorated my enthusiasm for electronics, and it wasn't long before I had reverse-engineered all the modules I then had, and my thirst for the knowledge to understand how they all worked grew greater and greater: how do oscillators work?; why does this arrangement of transistors give 1V/octave control?; what makes filters filter, and why are there so many different types? etc. After a few years I decided that I should actually seek employment in the hardware/electronics sector, despite the difficulty of having to switch disciplines from my previous experience in software/systems engineering. It quickly became clear that my PhD was a hindrance in trying to achieve this, and so I studied for an HNC in electronics to (partially) help offset this, and my efforts satisfactorily culminated in the job at Heber, which actually carried me through to the end of my working career.

Pedagogical approach

Over the years there have been many occasions when I've been able to reflect on the reasons why this second excursion into electronics & synthesizers was more successful than the first. Obviously greater maturity played a part (and included in that, increased academic maturity was undoubtedly a factor too). The college course I forsook after only one year took a typical bottom-up approach—study all the basic elements first: electrostatics, electromagnetism, semiconductor materials and basic devices, circuit laws, AC theory, phasors etc. This can be very 'dry' of course, with barely any real circuits involved at all, which I believe is partly why my enthusiasm for it waned so quickly.

In contrast, my approach the second time around has been from a much more top-down direction: with just the knowledge of some basic circuit laws, the concepts of gain and negative feedback, and some simple arithmetic, it is possible to understand a huge number of op amp circuits, with very little understanding needed of what is actually inside them that makes them work. Add to this the fact that in the context of synthesizer circuits it is easy to see and hear what the circuits do—the varying pitch of a voltage-controlled oscillator, the removal of harmonics by a filter, shaping of signals with envelopes and voltage-controlled amplifiers etc.—and for me this makes the whole electronics experience more enjoyable and circuits more accessible, and yet there is still plenty of scope for delving into the underlying theory if there is a desire or need to do so. Indeed, one of the problems I face endlessly is the fact that there is so much interesting stuff out there to explore, and so little time to do so.

[Page last updated: 20 Nov 2020]