# Stoicheia – A Euclidean Sequencer For Eurorack Modular Synthesizers

Rebel Technology, a new Eurorack module manufacturer, has introduced Stoicheia – a Eurorack format Euclidean trigger sequencer.

Stoicheia algorithmically generates rhythmic sequences from an input trigger signal. The name comes from the title of Euclid’s book Elements, in which the algorithm was first described.

If you’re not familiar with the idea of Euclidean sequences, Godfried Toussaint has published a paper (.pdf) that looks at how the Euclidean algorithm can be used to create sequences similar to traditional musical rhythms.

Stoicheia is driven by a micro controller which interfaces modular signal levels through discrete transistor networks. It functions by responding to incoming trigger signals using the MCU’s built in hardware interrupts. The step sequences are pre-calculated in the main processor loop and updated when the knobs are turned, which means that the interrupts can be processed very efficiently. This leads to a very low on/off latency.

Stoicheia can process clock signals well into audible frequencies.

Here’s a demo of the new sequencer in action:

Stoicheia is both an open source and open hardware design.  It’s available pre-built for £160. See the Rebel Tech site for details.

Dimensions

• Height: 3U / 128.50mm
• Width: 10HP / 50.50mm
• Depth: <30mm
• Weight: 135g

Power

• 16-pin Doepfer/Eurorack
• PTC fuse and diode protected
• +12v: < 10mA
• +5v: < 25mA
• -12v: 0mA

Impedance

• Outputs: < 1.1k
• Inputs: > 100k

Voltage Range

• Output low: 0v
• Output high: 5.1v

## One thought on “Stoicheia – A Euclidean Sequencer For Eurorack Modular Synthesizers”

1. mh

Besides being a music producer I am also a math student who is currently studying number theory. It’s so cool to see the Euclidean algorithm being used for music!!!