Modular Synths


It had to happen eventually – I’ve been looking at Modular Synths and getting increasingly interested in building a small rig, perhaps like Bob’s setup above?

Modular Synths, for the uninitiated, are built from individual modules such as oscillators, filters and amplifiers in the same way as the original Moog System shown above.  Modern modulars come in a number of different formats but the Eurorack system is growing fast. Popularised by Doepfer in Germany, Eurorack modules are 128.5 mm tall so fit neatly into a 3U rack height (133.35 mm). Module widths are measured in hp (1hp = 5.08 mm) so racks are characterised by linear capacity – “I’ve just filled my new 104hp case with modules…”

There’s a thriving business in new & used modules and in DIY kits for home assembly. There’s also lots of information online on DIY cases for Eurorack modules. They don’t have to be 19″ racks – make them any width you like with a DIY case. There are some great examples in the DIY Case thread on the Muffwiggler forum

If you’re thinking a 3U rack sounds like a 500- / 51X-Series rack, you’d be right, but there are major differences: Eurorack doesn’t have a backplane for the modules to plug into, voltages rails are different (± 12 Volts for Eurorack), power is connected to each module using a power cable and inputs & outputs are mounted on the front panel. Eurorack modules also vary hugely in depth and width with shallow units being under 45 mm deep

The Modular world is full of acronyms and buzzwords, even more so than the music world in general, so here’s a quick guide, written by a beginner for beginners, into Modular lingo:

  • Eurorack – a standard that fits in a 3U tall rack, uses 1/8″ patch cables
  • 5U rack – As used by Moog, Cynthia, etc, uses 1/4″ patch cables
  • hp – one rack width = 5.08 mm
  • 42 hp rack – a rack 42 hp wide, ie 213.36 mm wide, plus mounting
  • Skiff – a shallow case, usually less than 45 mm deep
  • Rails – the horizontal strips modules are attached to top & bottom
  • Busboard – used for power distribution to each module
  • 1 Volt / Octave – traditional standard for synth control voltages
  • VCO – Voltage Controlled Oscillator
  • VCA – Voltage Controlled Amplifier
  • VCF – Voltage Controlled Filter
  • CV – Control Voltage

I’ve compiled a few links useful for research into modular synth suppliers and DIY resources

Manufacturers, Shops & Online stores

More suppliers, added October 2020

DIY resources

Photo © Moog