The Moog Subharmonicon represents one of Moog's most unconventional synthesizers, originally conceived as a workshop project at Moogfest 2018 and later developed into a commercial product. Drawing inspiration from early 1930s instruments like the Trautonium and Rhythmicon, along with compositional concepts developed by Joseph Schillinger, the Subharmonicon eschews traditional analogue synthesis wisdom in favor of a unique approach based on fundamentals, sub-harmonics, and polyrhythmic sequencing.

Unlike conventional synthesizers that focus on harmonic overtones (2f, 3f, 4f, etc.), the Subharmonicon generates sub-harmonics—frequencies that are fractions of the fundamental (f/2, f/3, f/4, etc.). This creates intervals and combinations that can sound weird, wonderful, or completely otherworldly depending on the application.

Sound Generation

The Subharmonicon features two identical oscillators, each comprising a fundamental pitch generator plus two sub-harmonic generators capable of producing sounds ranging from the fundamental frequency down to f/16. Three waveform modes are available: sawtooth waves for all partials, square waves for all partials, and a hybrid mode combining square waves for fundamentals with sawtooth waves for sub-harmonics.

In hybrid mode, each oscillator's SUB1 sawtooth provides pulse-width modulation for the fundamental's square wave, creating unique PWM characteristics with distinctive "bumps" due to the sawtooth driving waveform. A six-channel mixer allows precise control over each partial's contribution before passing through Moog's signature 24dB/octave low-pass ladder filter with cutoff and resonance controls.

The signal path includes two contour generators—one for the VCF and one for the VCA—offering Attack and Decay phases, or Attack, Sustain, and Release when a gate is sustained. Notably, the filter contour operates as both single-triggering during attack and multi-triggering during sustain/release phases, enabling complex interactions with polyrhythmic sequences.

Sequencing and Polyrhythms

The heart of the Subharmonicon lies in its dual four-step sequencers and revolutionary polyrhythmic approach. Each sequencer can control the fundamental, SUB1, SUB2, or any combination of partials from its associated oscillator. When controlling sub-harmonics, the sequencer values determine the division integers rather than pitch offsets, creating dramatically different musical results.

Four rhythm generators derive their timing by dividing a master clock (ranging from 20 BPM to 3,000 BPM) by integers from 1 to 16. Each rhythm can drive either sequencer, both, or neither, creating complex polyrhythmic patterns that evolve over time. The system includes quantization options for both chromatic and diatonic scales in equal and just temperaments.

Semi-Modular Architecture

The Subharmonicon functions as a semi-modular synthesizer with a comprehensive 32-jack patchbay (17 inputs, 15 outputs) using 3.5mm connections for Eurorack compatibility. Signal ranges include 0-5V, 0-8V, 0-10V, and ±5V as appropriate, with 1V/octave scaling where relevant. The unit can be removed from its case to function as a 60HP Eurorack module, drawing 360mA from the +12V rail.

Performance and Connectivity

The instrument is designed for hands-on performance, encouraging real-time manipulation of filter parameters, contour settings, and rhythm assignments. MIDI implementation includes 11 controllable parameters via MIDI CC, though it currently lacks pitch-bend and modulation wheel response. The rear panel features a single quarter-inch output for both headphones and line output, plus a universal power supply connection.

Legacy and Innovation

The Subharmonicon continues Moog's tradition of releasing enhanced versions of Moogfest workshop projects, following the successful commercial releases of the Werkstatt (2015) and DFAM (2018). It represents a bold return to experimental synthesis concepts from the 1930s, reimagined with modern analog circuitry and expanded functionality. The instrument excels at creating evolving bass sequences, complex polyrhythmic patterns, and sounds impossible to achieve with conventional synthesizers.

Technical Specifications

Sound Engine

• Type: Analog synthesis
• Oscillators: 2 x VCO with fundamental + 2 sub-harmonic generators each
• Sub-harmonic Range: f to f/16 per oscillator
• Waveforms: Sawtooth, Square, Hybrid (Square fundamental + Sawtooth sub-harmonics)
• Pulse Width Modulation: Internal (SUB1 sawtooth modulates fundamental square wave)

Filter

• Type: Self-Oscillating Ladder Filter
• Response: Low-Pass, 4-Pole (-24 dB/Octave)
• Controls: Cutoff Frequency, Resonance
• Self-Oscillation: Yes (above ~2 o'clock resonance setting)

Envelopes

• VCA Envelope: Attack (1ms-10s), Decay (5ms-10s) - Positive polarity only
• VCF Envelope: Attack (1ms-10s), Decay/Sustain/Release (5ms-10s) - Bipolar
• Trigger Modes: Single-triggering (Attack), Multi-triggering (Sustain/Release)

Sequencers

• Type: Analog sequencers (x2)
• Steps: 4 steps per sequencer
• Quantization: Chromatic (Equal/Just temperament), Diatonic (Equal/Just temperament)
• Range Settings: ±5 octaves, ±2 octaves, ±1 octave
• Control Modes: Fundamental, SUB1, SUB2, or combinations

Rhythm Generation

• Rhythm Generators: 4 independent generators
• Division Range: Master clock ÷ 1 through ÷ 16
• Master Clock: 20 BPM to 3,000 BPM (1/3Hz to 50Hz)
• Clock Sources: Internal tempo, MIDI Clock, External Clock

Patchbay

• Total Jacks: 32 x 3.5mm (Eurorack compatible)
• Inputs: 17 jacks (±5V typical, 1V/octave where applicable)
• Outputs: 15 jacks (0-5V, 0-8V, 0-10V, ±5V ranges)
• MIDI Input: 3.5mm jack (Type A dongle included)

MIDI Implementation

• MIDI CCs: 11 controllable parameters
• Controls: Partial frequencies, Attack/Decay times, rhythm logic
• SysEx: Play on/off, MIDI channel selection
• Limitations: No pitch-bend or modulation wheel response (potential firmware update)

Audio Connections

• Output: Single 1/4" jack (TRS headphone or TS instrument)
• Output Impedance: Unbalanced line level
• Audio Quality: Moog analog signal path with characteristic warmth

Power Requirements

• Consumption: 4.8 Watts typical
• Input: 100-240VAC, 50-60Hz (universal wall adapter)
• Output: +12VDC, 1200mA
• Connection: Barrel connector, center-pin positive
• Power Switch: Always on when connected (no on/off switch)

Eurorack Specifications

• Module Size: 60HP
• Depth: 1" / 26mm
• Current Draw: 360mA maximum from +12VDC rail
• Power Header: Standard 10-pin Eurorack connector

Physical Dimensions

Standalone Unit

• Dimensions: 4.2" H x 12.57" W x 5.24" D (10.67 x 31.93 x 13.31 cm)
• Weight: 3.5 lbs (1.58 kg)

Shipping

• Box Dimensions: 8" H x 15" W x 9" D (20.32 x 38.1 x 22.86 cm)
• Shipping Weight: 6 lbs (2.72 kg)

Additional Features

• Security: Kensington lock slot
• Compatibility: Designed to integrate with Mother-32 and DFAM
• Stand Options: 2-tier and 3-tier vertical rack kits available
• Documentation: Complete manual with block diagrams and blank patch charts

Available Accessories

• 2-Tier Vertical Rack Kit
• 3-Tier Vertical Rack Kit
• Gig Bag
• 6" 3.5mm Cable Pack (Qty 5)
• 12" 3.5mm Cable Pack (Qty 5)
• Empty 60HP Case
• Empty 104HP Case