Synthesizer do it yourself

Synthesizer Do It Yourself (SDIY) or Synth DIY is about making, modifying, or repairing electronic musical instruments and related equipment yourself. Many people with an interest in electronics and music are now discovering that a Synth-DIY project is feasible. More advanced synth DIYers design and build their own synthesizers. What’s needed is a design, parts and tools, and especially the skills. Unless assembling relatively inexpensive circuits like the Atari Punk Console, synth DIY can be an expensive pastime.

Ability and know-how
The single most important factor in synth DIY is your skills. You'll need to be able to read and understand circuit diagrams, identify electronic components, and fault-find non-working circuits. The best way to learn is by building. Pick a small project to start with, to find out how you get on.

Tools
The least tools you can start with are a good soldering iron, a desoldering pump or braid, fine wire-cutters, long nose pliers and a decent digital multimeter. Also useful are an oscilloscope capable of DC coupled input, a solderless breadboard, a bench power supply, a function generator and a frequency counter.

EDA
For more advanced DIY there is also the requirement for suitable electronic design automation (EDA) software, for the schematic capture (design of schematics), PCB layout, Gerber files etc. such as CadSoft EAGLE, KiCad or DIYLC.

Kits and PCBs
PAiA have been producing analogue synth kits since 1967. The PAIA Fatman is a complete synth to build from a proven design. It has two VCOs and a good VCF similar to that of the second-series ARP Odyssey. The schematics are easy to follow and anyone is allowed to build it providing they don't market it as their own. There is a selection of links to bare PCBs and kits at Ken Stone's Modular Synthesizer site.

Designs
If you are not creating your own, there are already a number of designs to choose from. From individual modules to large systems based on classic CV/Gate controlled analogue synths, (such as the Moog modular), to MIDI controlled devices as with the open hardware MIDIbox project. As well as sequencers, samplers and associated equipment such as efects units and amplifiers.

To have reliable designs to work from, use circuits tried and tested by previous SDIYers. Refer to the list of external links section below for where to research for these.

Magazines
In the 1970s Electronic hobbyist magazines such as Practical Electronics (PE), Wireless World, Electronics Today International (ETI) and Elektor were at the forefront, publishing designs for the synth builder. To build some of those designs, one needed a firm grasp of electronics and constructing even the smaller models was not easy.

Things changed when ETI, in conjunction with a company called Powertran, released the design and a kit of parts for a single-oscillator synth called the Transcendant 2000. The article (by Tim Orr, formerly of EMS) was well planned, and Powertran provided everything you needed, down to the last nut and bolt, even including a mains plug. It was very popular, and spawned a range of synths including the Transcendant Polysynth, which was the kit-builder's Jupiter 8 without the memories. In 1979 ETI also published schematics for the Digisound 80 modular. This, like the Transcendant Polysynth, featured Curtis Electro Music synth chips. The CEM chips made kit building much easier.

The Elektor Formant synthesizer design was published in 1977/78, also modular and based around Moog Modular styling. Another early ETI design was the 4600 and its descendants, the 5600 and 3800 synths, which were distributed as kits by Maplin Electronics. The 4600 and the 5600 featured a pin matrix for patching similar to that of the EMS VCS3, only larger. However, these synths proved overly complex for the amateur constructor.

Bear in mind that magazine designs are frequently inaccurate or incomplete. The Practical Electronics Analogue Sequencer, for instance, published in April 1977, will not function correctly without the modifications published in September 1977.

Schematics
The Moog Modular manual is huge and contains all the schematic diagrams and some of the setup and calibration notes, but beware. Although the designs are all there, some of them use parts which may be hard or impossible to get hold of. It also has to be said that some modules, such as the oscillators and envelope generators, were better implemented in later designs such as the second-series Minimoog, Prodigy and Rogue. Schematics for the latter two are extremely readable, as are the associated setup notes, and the circuits work. Another synth from the past which makes a good construction project is the Oberheim SEM (Synthesizer Expansion Module). This synth isn't too difficult to construct, and features a voltage-controlled state-variable filter.

Using circuits from a former commercial product, using a schematic from a service manual can also be problematic, as these too can contain errors.

Books
Build a better music synthesizer by Thomas Henry was a good introduction to modular synthesizer construction. Electronic Music Circuits by Barry Klein describes the circuitry involved in modular synth design, in more depth. It is a good starting point to learn the technology as well as electronics in general. However for both of these books some of the components may be no longer readily available.

Electronotes and Preferred Circuits Collection by Bernie Hutchins is the definitive DIY circuit & theory collection. Still in publication, although more DSP based.

Web sites
There is an introduction to SDIY at Music From Outer Space, as well as parts and kits available for purchase. Use the Wayback Machine to view former websites, now no longer available.

Wikipedia is a great resource. All About Circuits for well explained stuff. Doctronics is a good reference for ICs when you're not sure what something does. At Aaron's Synth DIY there is a list of useful parts. At Birth of a synth there are some DIY modules, with explanations, for example the VCO-1. Although it is better to practice with very simple circuits before starting this kind of project, even though this is a fairly simple circuit.

Aaron Lanterman's lectures ECE4803B: Theory and Design of Music Synthesizers, 2006 as well as ECE4893A: Electronics for Music Synthesis, 2010 and 2008 are available online.