Duophonic from Monophonic with Beatstep Pro & Dark Energy

Published on Feb 24, 2020 DreamsOfWires

"Just a really simple trick people who are new to analogue synths might want to try. It'll work with any synth that has both a VCF that'll self-oscillate and external control over filter frequency. It'll work best if the filter can track 1v/oct with some stability. Also, you could substitute the Beatstep for another multi-channel CV sequencer or controller, such as a Korg SQ-1 in dual mode.

Basically, on certain filter designs, when resonance is maxed and it's frequency lowered it'll start to produce a simple sine wave (self-oscillation). In many synths this sine wave can be controlled melodically (with varying success), independently of the VCO. Here's how it works in this video:

One sequencer channel's CV output goes to the synth's VCO pitch input, and the other channel's CV out to VCF frequency input. The gate out goes to gate in as usual.

Firstly, get a single note playing and make sure you can hear the VCO, max the resonance, then reduce the filter frequency manually and you'll start to hear the filter self oscillating, which essentially creates a pitched sine wave. Adjust the frequency until it sounds like it is in tune with the VCO. You'll have to experiment with different tunings and octaves of both to get your desired result. Also, experiment with raising the resonance just enough to start self-oscillating, as this should lower the volume of the resonance against the VCO's volume, allowing you to hear both more clearly.

Now you can start knob twiddling on the sequencer, creating separate melodies on both channels, and even have different sequence lengths and time divisions for some polyrhythm fun.
Dry sound from 2:03

Gear used: Doepfer Dark Energy Mk1, Arturia Beatstep Pro, AUM on an iPad with Dubstation2 delay and EOS2 reverb. Video edited on iPad as my computer is still broken.

My music/albums can be found here:
https://tomorrowthecure.bandcamp.com
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