DIY SH-101 like Sub-oscillator (SUB 101A rev 1.5) for any Modular or semi-modular synths

The SUB 101A (rev 1.5) is available as a KIT (PCB + Parts + Box + Cables) or fully build (with enclosure for desktop use + Power cable).

If you want to add some juicy low end to your Moog Mother 32, Behringer Crave or Neutron, this Sub-Oscillator will do the job !

This little fellow is inspired by the famous Roland SH-101 Sub Osc and runs on 9V battery or 12V power supply.

I put together a circuit that adds a square wave sub-oscillator to your semi-modular synth for some really beefy tones

This Sub Oscillator tracks an oscillator signal from a VCO and generates a square wave at -1 or -2 octaves below. Works best with sawtooth, triangle, Sinus waveforms or simple square waves.

There’s a pot that mixes between the 2 sub-octaves and if you set it to 50% it sounds just like the famous Roland SH-101 pulse sub-oscillator.

For this to work, you need to route the oscillator output of your synth into the sub-oscillator Input. Then you get the sub-oscillator signal at the output. Mix it back with the original through an audio input chanel to enjoy that juicy low end.

This PCB is safe RoHs compliant (Lead Free).



BOM list Sub 101A (Rev1.5) for Eurorack

REF. VALUE DESCRIPTION COMMENT

D1 Red LED Ø 3mm (20mA)
D2 1N4002 Rectifier Check polarity before soldering
D3 1N4148 High-speed diode Check polarity before soldering
R2 27K 1/4W 5% or 10K Metal Film or Carbon
R1, R3, R4, R7 10K 1/4W 5% Metal Film or Carbon
R5, R8 120k 1/4W 5% Metal Film or Carbon
R6 1M 1/4W 5% Metal Film or Carbon
C1 100uF (16V) Electrolytic Check polarity before soldering
C2 100nF (50V) Ceramic
C3 10uF (16V) Electrolytic optional : Not used for Eurorack
C4, C6 10uF (16V) Electrolytic Check polarity before soldering
C5 10nF (50V) Ceramic
Q1, Q2 2n3904 NPN BJT Or BC547 / BC548
RV1 B10K Potentiometer Linear Pot RK09 / PTV09A or similar
U1 CD4013 CMOS Dual D Flip Flop
J1, J2, J3 PJ301M-12 Audio Jacks 3x 3.5mm Audio Jacks Female
J4 2 x 5 Pin Pin header To connect it to a Eurorack PSU