Carmelo Azzarello of YouTube channel Analog Lab has put together a circuit that adds a square wave sub-oscillator to the Behringer single oscillator Crave (or other synths) for some really beefy tones.
This DIY Sub Oscillator tracks the oscillator output of the Crave and generates a square wave at -1 or -2 octaves below. Works best with sawtooth and triangle waveforms and simple square waves but is not so fond of pulse width modulation.
It doesn’t have to be tied to the Crave as it can, in fact, work with Eurorack and other synths like the Neutron. It’s simply that the Crave is what Carmelo was trying to augment.
The circuit is pretty straightforward. It uses a CD4013 dual flip-flop IC to output the -1 and -2 octave signals simultaneously. There’s a 100k pot that mixes between these sub-octave signals and apparently if you set it to 50% it sounds just like the SH-101 pulse sub-oscillator.
It’s all put together on a small bit of stripboard and runs one 9V battery or 12V power supply.
To make it work you need to route the oscillator output from the Crave, or whatever you are using, into the Sub-Oscillator. You may have to split your output or use a mult to achieve this. And then you have the sub-oscillator mix as an output. Mix it back with the original to enjoy that juicy low end.
The video demonstrates the sound and at the end it guides you through the build process including the circuit diagram and Bill of Materials (BOM). What a great way to add some depth to a small synth or simple Eurorack oscillator.
- Analog Lab Instagram.