Another Moog Subharmonicon

Subharmonicon II

I’ve made a re-imagined clone of the Moog Subharmonicon. A lot of credit goes to @Achro as I did use his excellent patch as a starting point. I wouldn’t have even embarked on this build if not for that patch, so big thanks are due.

Where @Achro’s patch was based on the Moogfest2018 version, this one is based on the production version which had a significantly different feature set, and also contains a bunch of other features that I wanted because, why not in the digital realm? :upside_down_face: I’ve called it a Subharmonicon II for lack of a better way of differentiating them.

Significant differences to the hardware

  • Expanded Quantizer with ability to change root note of the scale and optionally tune the sub oscillators.
  • Independent filter and amp sections for oscillator 1 and 2 (with ability to link controls).
  • Stereo width for oscillator 1 and 2 (width knob acts as a crossfade if using a mono out from the patch bay).
  • Ability to decouple the gates from sequencer 1 and 2.
  • Spring reverb.
  • PWM setting replaced with a different oscillator shape (I wasn’t enjoying the PWM setting).
  • PWM input in the patch be replaced with oscillator sync (as I haven’t figured out how to PWM my splined square wave yet).
  • Patch bay inputs cut down based on the philosophy that if you can cable directly to a knob, it doesn’t need to be in the patch bay.



Control Section

Control Function Notes
Screen Shot 2020-11-25 at 9.54.44 pm Tempo 20 to 3,000 BPM. You will be dividing this down which is why it goes so high.
Screen Shot 2020-11-25 at 9.54.50 pm Volume
image Start/Stop Sequencers
image Reset Sequencers
image Trigger Gates With current sequence values.
image Progress Sequencers
image Overlapping Gate Logic XOR - exclusive or. Only a single gate will progress the sequencer.
OR - Any number of overlapping gates will progress the sequencer.

Polyrhythm Section

Screen Shot 2020-11-25 at 9.55.03 pm
Each of the four knobs represent individual tempo dividers. These knobs divide the master tempo by an integer value between 1 (full left - fast) and 16 (full right - slow). Each of the resulting gates can be assigned to Sequence 1 and 2 using the SEQ assigned buttons.
Screen Shot 2020-11-25 at 9.55.08 pm
Turning this on causes the progression of either sequencer to trigger the envelopes for both Oscillator 1 and 2. On is the default behaviour of the hardware.

Sequence Section

Screen Shot 2020-11-25 at 9.56.13 pm
The two sequence sections represent individual four step sequencers. Sequence 1 drives Oscillator 1 and Sequence 2 drives Oscillator 2. The knob values at each of the four steps are combined with the static knobs from the Oscillator section. Values to the right Add CV to the oscillator section knobs, while values to the left Subtract CV from the oscillator section knobs. In the center position the sequence value will have no effect.

Oscillator Section

Osc 1 and 2 sections are identical.

Control Function Notes
Screen Shot 2020-11-25 at 9.55.57 pm Main Osc Frequency 2 octave range from middle C
Screen Shot 2020-11-25 at 9.56.05 pm Sub Dividers 1/2 Divide the main osc frequency by an integer value between 1 (full left - high pitch) and 16 (full right - low pitch).
Screen Shot 2020-11-25 at 9.55.46 pm Octave Range Selector Selects the octave range of the sequencer knobs.
Screen Shot 2020-11-25 at 9.55.40 pm Osc Wave Shape Selector Selects wave shape for all 3 (main and sub) oscillators. See below for notes on wave shapes.

Oscillator Shapes

Screen Shot 2020-11-26 at 1.42.31 pm
Square - roughly based on an image of the square wave from a Sub Phatty (I think…) using a spline node.
Screen Shot 2020-11-26 at 1.42.42 pm
Batman - based on ducking a sine wave and using that as the carrier for the above square wave.
Screen Shot 2020-11-26 at 1.42.20 pm
Saw - based on discrete-time modelling of the saw wave from a Minimoog Voyager from this article.

Mixer Section

Mixer 1 and 2 sections are identical.

Control Function Notes
Screen Shot 2020-11-25 at 9.55.20 pm Sequencer Assignment Determines which knobs from the oscillator section will be affected by the sequencer. If no buttons are lit, the sequencer has no effect. Seq 1 drives Osc 1; Seq 2 drives Osc 2.
Screen Shot 2020-11-25 at 9.55.29 pm Oscillator Volumes
Screen Shot 2020-11-25 at 9.55.33 pm Oscillator Stereo Spread Oscillators can be spread to either side. Centre position is mono. If using a single audio out from the patch bay, this knob functions as a cross fade.

Filter Section

Filter 1 and 2 sections are identical.

Control Function Notes
Screen Shot 2020-11-25 at 9.56.24 pm Cutoff
Screen Shot 2020-11-25 at 9.56.29 pm Resonance
Screen Shot 2020-11-25 at 9.56.33 pm EG Amount Positive and negative amounts. Centre position has no effect.
Screen Shot 2020-11-25 at 9.56.37 pm Attack
Screen Shot 2020-11-25 at 9.56.42 pm Release
Screen Shot 2020-11-25 at 9.55.14 pm Link Filter & Amp 1 knobs also control Filter & Amp 2.

Amplifier Section

Amp 1 and 2 sections are identical. Note that the link button above also affects the amp section.
Filter 1 and 2 sections are identical.

Control Function Notes
Screen Shot 2020-11-25 at 9.56.51 pm Attack, Release.


Bypasses the amp envelope. Envelope is still available at the patch bay.

Reverb Section

Standard spring reverb module applied separately to Oscillator 1 and 2.
Screen Shot 2020-11-25 at 9.57.02 pm

Patch Bay

Control Signal Range Notes
Screen Shot 2020-11-27 at 9.16.47 am Gate 0-1 Run the sequencers from here when the internal clock is stopped.
Screen Shot 2020-11-27 at 9.16.51 am Gate 0-1 Reset the sequencers and clocks (same as Reset button).
Screen Shot 2020-11-27 at 9.16.55 am Gate 0-1 Trigger both envelopes (same as Trigger button).
Screen Shot 2020-11-27 at 9.17.01 am Gate 0-1 Trigger Filter and Amp for Oscillator 1. Same for Gate 2.
Screen Shot 2020-11-27 at 9.17.06 am Modulation 0-1 Oscillator Sync for primary Oscillator 1 (not the subs). Same for Sync 2.
Screen Shot 2020-11-27 at 9.16.42 am Gate 0-1 Master clock out.
Screen Shot 2020-11-27 at 9.15.53 am Gate 0-1 Individual clock out for Rhythm generator 1. Same for Rhythm 2-4.
Screen Shot 2020-11-27 at 9.16.06 am Modulation 0-1 Envelope out. Same for VCA and VCF EG 1 and 2.
Screen Shot 2020-11-27 at 9.16.11 am Gate 0-1 Gate out for Sequencer 1. Same for Gate 2.
Screen Shot 2020-11-27 at 9.16.23 am Modulation 0-1 Sequence 1 values. Same for Seq 2.
Screen Shot 2020-11-27 at 9.16.00 am Audio -1 to 1 Audio out L/R. If only using one, the Width knob acts as a crossfade.
Screen Shot 2020-11-27 at 9.15.44 am Audio -1 to 1 Intermediate audio outs from the oscillators. Note these are not DC Blocked, mainly because the sub outs make good glitchy Modulation sources, especially on the square wave setting when the pitch is really low. The sub outs are capable of generating pitches below 20hz. This can damage your speakers so if you are using these outs for audio, just make sure you include a DC Blocker node somewhere in your audio path. The main outs (L/R) and internal speaker are both DC Blocked.

Version History

Revision File Date Notes
1.0 Subharmonicon II.audulus (1.2 MB) 11/28/2020


Patch come set up for a demo. Just open the patch and press Play :slightly_smiling_face:


Oh man. Wow! :evergreen_tree: :gift: Such a good layout.


OMG :scream::exploding_head::partying_face: another one knocked straight out of the park!!! WELL DONE @zilch42! I don’t think I will actually accomplish anything on my to-do list tonight (or tomorrow lol) :blush:


Nice work!

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