Make Noise DPO
Dual analog VCO with FM, Sync, and wave folding
28 HP Eurorack module
The DPO (Dual Primary Oscillator) is a 100% analog voltage-controlled oscillator module featuring two fully-featured VCO cores, each capable of generating complex, harmonically rich waveforms through internal FM, Hard Sync, and Timbre Shaping circuits. Both oscillators can act as carriers or modulators, with internal FM and Mod buses enabling bidirectional Cross FM, wave folding, and additive harmonic synthesis without any patching. The module has a vintage, organic character shaped by opto-isolators throughout, giving it slow and musical responses to control signals.
Features
- Dual fully-featured analog VCO cores, both operable as complex signal sources
- Internal bidirectional FM Bus with sine wave normalling in both directions
- Internal Mod Bus with VCO A Sine normalled as modulation source for Shape, Angle, and Fold
- External Source Input interrupts Mod Bus internal routing for custom modulation sources
- VCO A selectable core behaviors: Standard, Lock (Blue), Hard Sync (Pink), LFO (Amber)
- VCO B External Lock input for weak phase-reversed synchronization to external VCO
- Follow circuit allows VCO A to track VCO B pitch with adjustable lag
- FM Bus Index control with CV input and attenuverter for dynamic FM depth control
- Mod Bus Index control with CV input and attenuverter for dynamic timbre modulation depth
- Shape parameter: morphs from Sine to Spike to Glitched Triangle with phase reversal and AM around 12 o'clock
- Angle parameter: tilts waveform feeding Fold circuit, enabling asymmetrical folding and phase shift/PWM effects
- Fold parameter: continuous wave folder with additive harmonic synthesis character, first 30% acts as VCA
Controls & Jacks (47)
- Triangle Waveform Output — Audio output for the triangle waveform from VCO B. Produces a smooth, mellow tone with odd harmonics.
- Sawtooth Waveform Output — Audio output for the sawtooth waveform from VCO B. Rich in harmonics, useful for subtractive synthesis.
- Sine Waveform Output — Audio output for the sine waveform from VCO B. Pure fundamental tone with no harmonics.
- Beat Frequency — Visual indication of phase difference between VCO A and VCO B
- Beat Frequency Output — Outputs the beat frequency — the difference tone generated between the two oscillators when tuned close together.
- Square Waveform Output — Audio output for the square waveform from VCO B. Hollow sound with odd harmonics, good for pulse-width effects.
- FINAL Waveform — Final processed audio output combining both VCOs through the waveshaping and modulation stages.
- Angle CV Input — Unipolar attenuator for Shape CV input
- Follow CV Input A — Unipolar control input for VCO A following behavior
- Shape — Morphs the waveform feeding the Fold circuit from Sine (full CCW) through Spike (noon) to Glitched Triangle (full CW). Also introduces phase
- Angle — Tilts the waveform within the Fold circuit, pushing harmonics to one side or the other of the wave cycle. Creates asymmetrical folding with
- Coarse Tune A — Sets the base frequency of VCO A across a wide range spanning approximately 9.5 octaves.
- Coarse Tune B — Control voltage input for Shape parameter modulation
- Shape CV Input — Unipolar attenuator for Angle CV Input
- Follow Attenuator — Determines how well VCO A follows VCO B. Works as panel control or attenuator for Follow CV Input signal
- Shape CV Attenuator — Unipolar attenuator for the Shape CV Input. Controls how much the incoming CV (or internally normalled Mod Bus signal) modulates the Shape p
- Angle CV Attenuator — Unipolar attenuator for the Angle CV Input. Controls how much the Mod Bus or a patched CV modulates the Angle parameter.
- Fine Tune A — Fine-tunes the frequency of VCO A across a narrow range for precise pitch and beating adjustments.
- Fine Tune B — Bipolar control signal input, normalled to Mod Bus, 8V range
- Expo Attenuator A — Scales the exponential pitch CV applied to VCO A from the Expo Input jack.
- Scale Trimmer A — Calibration trimmer for VCO A 1V/octave tracking accuracy. Not intended for performance use.
- VCO A Core LED 1 — Indicates the oscillation rate of VCO A. Blinks at the oscillator frequency when in LFO range.
- VCO A Core — Visual indicator of VCO A core waveform activity and current core behavior mode.
- Follow Attenuverter — Bipolar attenuverter controlling the amount and polarity of the Follow (hard sync) signal applied between oscillators.
- FM Bus — Indicates activity on the FM Bus. Brightness reflects the amount of FM modulation being applied.
- Expo Attenuator B — Scales the exponential pitch CV applied to VCO B from the Expo Input B jack.
- Mod Bus Index Attenuator — Master depth control for the Mod Bus, which routes VCO A Sine (or an external source) to the Shape, Angle, and Fold CV inputs. Increasing th
- Fold Attenuverter — Bipolar attenuverter for the Fold CV input, controlling wavefold depth and polarity.
- Linear FM Attenuator A — Scales the amount of linear frequency modulation applied to VCO A.
- VCO A Core — Toggles VCO A between different core behaviors, changing the fundamental oscillator waveform character.
- FM Bus Index — Unipolar panel control that sets the index (depth) of the FM bus modulation
- Linear FM Attenuverter B — Bipolar attenuverter controlling the amount and polarity of linear FM applied to VCO B.
- Mod Bus Index — Master depth control for the Mod Bus, which routes VCO A Sine (or an external source) to the Shape, Angle, and Fold CV inputs. Increasing th
- Mod Bus — Indicates activity on the Mod Bus. Brightness reflects modulation depth.
- Fold CV Attenuator — Unipolar attenuator for Fold CV Input
- External Lock — Input for external sync/lock signal. Hard-syncs VCO A to an external oscillator or signal.
- Expo Input A — Exponential pitch CV input for VCO A. Accepts 1V/Oct or other exponential CV sources with attenuation.
- 1V/Oct Input A — Primary pitch input for VCO A. Tracks 1 volt per octave for standard pitch CV control.
- Linear FM Input A — Linear frequency modulation input for VCO A. Modulates pitch linearly for metallic FM tones.
- FM Bus CV Input — Indicates the currently programmed FM Index value
- Follow CV Input B — CV input for the Follow circuit. Controls hard sync behavior between the two oscillators.
- 1V/Oct Input B — Primary pitch input for VCO B. Tracks 1 volt per octave for standard pitch CV control.
- Expo Input B — Exponential pitch CV input for VCO B with attenuation via the Expo Attenuator B knob.
- EXT SRC — External source input for the Mod Bus. Replaces the internal modulation source with an external signal.
- INDEX — Master depth control for the FM Bus, which routes VCO A Sine to VCO B's FM inputs and VCO B Sine to VCO A's FM inputs simultaneously. Increa
- Strike Input — Gate/clock input that briefly opens the Fold circuit to 100%, expects 8-10V gate or clock
- Fold CV Input — Unipolar control signal input, normalled to Mod Bus, range 0V to +8V
How-To Guides
- Animated Lead with Strike Accents
- Bass Drum from VCO A
- Skronky FM with Pitch Slide
- Wobble Bass
- Strike Force Pressure Lead
- Circular FM Drone
- Hard Sync Harmonic Sweep
- Additive Fold Bass
- LFO Angle Shimmer
- External Lock Amplitude Modulation
Explore the interactive DPO panel on BleepDex — tap any control to learn what it does.
