The latest loopop video takes a look at the ERM Polygogo, a Eurorack module that lets you explore Polygonal Synthesis.

The module is essentially a complete stereo synth voice in Euro format. It can be used independently to create a wide range of sounds or integrated with other modules to create more complex patches.

Polygonal Synthesis is an approach created by ERM’s Maximilian Rest and Christoph Hohnerlein. It is based on complex two dimensional amplitude shaping of sine waves, combined with internal modulation sources and a new type of wave folder.

Five parameters let you modulate the sound:

Order defines the number of corners on the polygon, which can range from a line (order 2) to an almost perfect circle (order 28) with all fractional settings in between. The number of corners defines the ratio of overtones with respect to the fundamental frequency: a low count keeps the harmonics near the fundamental frequency, a high order shifts them up.

defines the number of corners on the polygon, which can range from a line (order 2) to an almost perfect circle (order 28) with all fractional settings in between. The number of corners defines the ratio of overtones with respect to the fundamental frequency: a low count keeps the harmonics near the fundamental frequency, a high order shifts them up. Teeth tilts the sides of the polygon out of the normal orientation and can be used to control the loudness of the overtones. It creates discontinuities in the waveform and acts as balance between the fundamental frequency and the overtone spectrum.

tilts the sides of the polygon out of the normal orientation and can be used to control the loudness of the overtones. It creates discontinuities in the waveform and acts as balance between the fundamental frequency and the overtone spectrum. Roll rotates the object around the center and animates the waves.

rotates the object around the center and animates the waves. Operator modulates the fundamental frequency for ‘FM madness’. FM Ratio is settable and quantizable, FM Amount goes from ‘subtle growls in the lows to aliasing madness’ at high frequencies.

modulates the fundamental frequency for ‘FM madness’. FM Ratio is settable and quantizable, FM Amount goes from ‘subtle growls in the lows to aliasing madness’ at high frequencies. Fold overflows the wave to the other side, leading to ‘tickling noise at low settings and crushing and slicing the waveform to total distortion’ when fully turned up. This digital artifact was reproduced in analog circuitry and delivers the most crisp and open sound.

Video Summary:

“ERM’s Polygogo is a stereophonic, single voice Polygonal Synthesis based Eurorack module. Polygonal synthesis was invented by ERM, and the basic idea behind it is to generate two separate stereophonic waveforms based on a circular XY scan of a two-dimensional shape. Various manipulations on these 2D shapes, like morphing the number of vertices, bending them inwards or expanding them outwards, change the harmonic structure of this module’s sound in interesting and sometimes surprising ways.

In this review I explore the various timbral components of Polygonal Synthesis and give a few patch idea examples that attempt to stretch it as far as possible.”

Topics covered

0:00 Intro

0:30 What is it?

1:50 Build

2:10 Order

3:30 Cycle

4:50 Teeth

5:40 Fold

7:05 Roll

8:15 Operator

9:45 Add reverb…

10:40 PATCH IDEAS

10:55 Vibrato

11:40 Sync

13:30 Exp FM+sync

14:00 PWM?

15:05 Mod all

15:45 Rnd per note

17:40 Rnd per phrase

18:00 Freeze chords

19:25 Fold hack

21:00 Fold VCA

23:05 Teeth VCA

24:00 Pros & cons

25:30 Outro jam

Pricing and Availability

The ERM Polygogo is available now for 539 Euro.