Chorus

Chorus waveform multiplier

Summary

If you want a richer sound from your VCOs, add this chorus module to your rack. This module generates six copies of the input saw wave, each out of phase with the original and with each other. The phase differences are continually changing using six internal trapezoid oscillators. This effect replicates six VCOs tuned closely together to generate a rich, dynamic super saw wave.

How it works

The multiplier consists of six phase shifting comparators that generate new sawtooth waves from the input. A six stage trapezoid oscillator drives each comparator high in 1/3 cycle increments. Three phases oscillate at about 0.6Hz and three at about 0.4Hz. The constantly changing phase relationships create shifting saw waves which are combined with the original saw wave at the output. Note that the output is a ramp for a saw wave input and the output is a saw for a ramp input.

Features

• Simple build with commonly available parts
• Oscilloscope needed for calibration
• 4HP Eurorack with our panel
• Can be combined in parallel and series for more interesting sound variations

Documentation

Comprehensive documentation, parts lists are provided in the documentation link for building, testing and calibrating the module.

[This module is a tribute to David Ward-Hunt who designed a waveform multiplier unit that was subsequently included in the Digisound-80 synthesiser. https://www.discogs.com/artist/14979-Wavestar]

https://www.tindie.com/stores/pmfoundations/