Synth DIY: Adding A Sub Oscillator

We're always in need of more low end aren't we? As we've discussed, modifying gear can be a a glorious way to expand the sonic palette, though not without it's risks. There are many sub oscillator modifications you'll find online, for the likes of the Yamaha CS-10, Jen SX1000 and now the Behringer Crave too. 

In this video, Analog Lab Swiss concisely demonstrates how to add a sub oscillator to the Behringer Crave which will also work for Eurorack synths - offering a PCB to help those not prepared to build on a breadboard. He adds:

It tracks a Sawtooth or Triangle signal (10Vpp with 0 offset) or a simple Square wave and output a -1 and a -2 octaves down Square waves. Avoid PWM signals. It'll not be good at tracking them.

It was tested at 9V and 12V and works well with Crave & Neutron Synths from Behringer but also with Eurorack's VCO. CD4013 is powered from 0 and 9V (or 12V). The 100k linear potentiometer acts as a mixer to blend the 2 sub osc signal output.

At 50% position, it'll output the famous SH-101 Pulse sub oscillator. The BJT can be a 2n3904 or a BC548 or a BC337.

If you're interested in sub oscillator mods, it's always worth googling the term for your synths - just be aware that modification is for life and you should seek help if you're not sure about anything. 

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