DPO

Make Noise 28HP

Dual Primary Oscillator. Two analog complex VCOs with shared FM/Mod buses, Shape/Angle/Fold wavefolder on VCO B, Hard Sync, Lock, LFO mode and vactrol Strike. Buchla 259 lineage.

Patch Ideas · 10

★ Animated lead (classic DPO voice)

VCO A in LFO mode animates VCO B's Timbre via the Mod Bus while Follow keeps the harmonic relationship locked to the sequence.

Walkthrough

Patch your sequencer's pitch CV → DPO VCO B 1V/Oct Input.
Set Shape panel control to 12:00, Shape CV attenuator to 12:00, Angle panel control to 12:00, Angle CV attenuator to 12:00.
Set Fold panel control to 9:00 and Fold CV attenuator to 12:00.
Set Mod Bus Index panel control to 12:00 — VCO A Sine (now LFO) feeds Shape/Angle/Fold equally.
Press the VCO A Mode button until the LED is Amber (LFO mode).
Set VCO A FREQ to around 9:00 so the LFO runs slow.
Turn the Follow knob full CW — VCO A now tracks VCO B's pitch, so modulation speed rises per octave.
Patch your sequencer's gate → DPO Strike Input for per-note Fold accents.
Patch DPO VCO B FINAL → your mixer or output.

Signal out VCO B FINAL — the post-Timbre audio output, up to 10Vpp, animated per note.

Listen for A bright, evolving lead: each sequencer note arrives with a Fold-driven accent, and the timbre pulses with a tracked LFO so fast notes shimmer and slow notes breathe. Raise Mod Bus Index for heavier animation.

▸ Show diagram

Bass drum

Linear FM from stepped random voltages gives VCO A a different FM character per hit, then Optomix shapes the kick envelope.

Walkthrough

Set VCO A FREQ panel control to roughly 9:00 for a kick fundamental.
Set the VCO A Linear FM attenuator to 12:00 (unipolar, half depth).
Patch DPO VCO A Sine Output → Optomix CH 1 Signal Input.
Patch Wogglebug Stepped Random → DPO VCO A Linear FM Input.
Patch Wogglebug Clock → Optomix CH 1 Strike Input (also triggers the kick envelope).
Turn Optomix CH 1 DAMP and CONTROL knobs full CCW for a short, tight body.
Patch Optomix CH 1 Output → your mixer or output.
Optional: mult the same clock → DPO FM Bus Index CV Input, attenuverter CW, for dynamic FM expansion per hit.

Signal out Optomix CH 1 Output — a percussive kick, roughly ±5V, pitched by VCO A FREQ.

Listen for A punchy analog kick drum with a slightly different FM crunch on every strike. Lowering VCO A FREQ gives deeper subs; raising the Linear FM attenuator adds more metallic edge.

▸ Show diagram

Skronky FM

Hard Sync plus a partial Follow setting lets VCO A slide into sync on each new note, squelching as it catches up.

Walkthrough

Tune VCO A and VCO B FREQ knobs to a simple interval — unison, fifth, or octave.
Press the VCO A Mode button until the LED is Pink (Hard Sync to VCO B).
Set Follow panel control to about 3:00 — VCO A lags slightly behind sequencer note changes.
Set the VCO B Linear FM attenuverter to 12:00 for moderate bidirectional FM via the Mod Bus.
Set FM Bus Index panel control to 12:00.
Patch your sequencer's pitch CV → DPO VCO B 1V/Oct Input.
Patch DPO VCO B Sine Output → your mixer or output.
Play the sequence — listen for the glissando-skronk on each note change.

Signal out VCO B Sine Output — 10Vpp sine carrying dynamic sync sidebands.

Listen for Each note triggers a brief, discordant FM squelch as VCO A slides into sync with VCO B. Turning Follow toward full CW tightens the response; toward CCW the skronk becomes more pronounced.

▸ Show diagram

Strike Force (Pressure Points expressive voice)

Pressure Points drives pitch, Strike, and Mod Bus all from one hand — pressing harder opens Fold while damping Timbre via external Mod Bus source.

Walkthrough

Turn Shape panel control and Fold panel control full CCW (zero).
Set Shape CV attenuator and Fold CV attenuator to 12:00.
Patch Pressure Points Tuned Output B (or C) → DPO VCO B 1V/Oct Input.
Patch Pressure Points Common Gate → DPO Strike Input.
Patch Pressure Points Common Pressure → DPO Mod Bus External Source Input (this replaces VCO A Sine as the Mod Bus source).
Set Mod Bus Index panel control to 12:00.
Patch DPO VCO B FINAL → your output.
Touch a Pressure Points pad, gradually increasing pressure — Strike opens the Fold while pressure shapes Timbre.

Signal out VCO B FINAL — up to 10Vpp audio, dynamically voiced by touch pressure.

Listen for A one-finger expressive voice: light touch gives a quiet, damped tone; heavier pressure makes the sound simultaneously louder and more harmonically rich as Strike kicks in and the Mod Bus drives Shape/Angle/Fold.

▸ Show diagram

★ Wobble bass

VCO A as LFO modulates VCO B's Timbre, and Follow makes the wobble rate double per octave so it stays musical across the bassline.

Walkthrough

Set Fold panel control to 12:00, Angle panel control to 12:00, Shape panel control to 12:00.
Set Fold CV attenuator, Angle CV attenuator, and Shape CV attenuator all to 12:00.
Press the VCO A Mode button until the LED is Amber (LFO).
Set VCO A FREQ panel control to around 9:00 — slow wobble.
Turn Mod Bus Index panel control full CW.
Turn FM Bus Index panel control full CCW (no cross-FM).
Turn Follow panel control full CW so VCO A LFO tracks VCO B pitch.
Patch your sequencer's pitch CV → DPO VCO B 1V/Oct Input.
Patch DPO VCO B FINAL → a filter → your output.

Signal out VCO B FINAL — up to 10Vpp wobbling bass audio, rate proportional to pitch.

Listen for Dubstep-style wobble bass where higher notes wobble twice as fast as lower notes, keeping the rhythm of modulation musically consistent. Rolling Follow back CCW breaks the lock and the wobble rate stays fixed.

▸ Show diagram

Cross-FM drone

With both VCOs tuned to an interval and FM Bus Index near overdrive, a slow LFO on the Index CV pushes the pair in and out of FM chaos.

Walkthrough

Press the VCO A Mode button until no LEDs are lit (standard triangle core).
Tune VCO A FREQ and VCO B FREQ to a consonant interval (unison or a fifth).
Set both Expo attenuators and Linear FM attenuators to 12:00 so the FM Bus reaches both sides evenly.
Set FM Bus Index panel control to around 2:00 — right at the edge of overdrive.
Set FM Bus Index CV attenuverter to 12:00 (half positive depth).
Turn Follow panel control full CCW — VCO A stays independent for a drifting drone.
Patch a slow LFO (~0.1 Hz) → DPO FM Bus Index CV Input.
Patch DPO VCO B FINAL → your output.

Signal out VCO B FINAL — up to 10Vpp evolving cross-FM drone.

Listen for A slowly shifting drone that breathes between clean interval tones and snarled bi-directional FM chaos as the Index crosses the 80% overdrive threshold. Retune VCO A/B for different harmonic bases.

▸ Show diagram

External Lock chord stack

Chain two DPOs via External Lock so their VCO Bs stay harmonically related without drifting — stack both FINALs for a locked chord.

Walkthrough

On DPO 1, tune VCO B FREQ to the chord root.
On DPO 2, tune VCO B FREQ to a 3rd or 5th above.
Patch DPO 1 VCO B Square Output → DPO 2 VCO B External Lock Input.
Leave both DPOs in standard mode (no Sync/Lock/LFO LED on VCO A).
Patch DPO 1 VCO B FINAL → Mixer Input 1.
Patch DPO 2 VCO B FINAL → Mixer Input 2.
Fine-tune DPO 2 FREQ until it locks to the interval — External Lock pulls it to an integer relationship.
Patch Mixer Output → your output. Add more DPOs the same way for thicker chords.

Signal out Mixer Output — summed chord at modular level, each DPO contributing up to 10Vpp.

Listen for A stable, detune-free chord where the master DPO sets pitch and the slave tracks it harmonically. Nudging DPO 2 FREQ Fine Tune produces slight amplitude cancellations because External Lock is phase-reversed.

▸ Show diagram

★ West-coast bongo

Strike opens Fold into a percussive chirp that is then plucked by Optomix — classic Buchla-style bongo from one gate.

Walkthrough

Set Shape panel control full CCW (Sine), Angle panel control to 12:00, Fold panel control to 9:00.
Set Fold CV attenuator to 12:00.
Patch a random CV source (sample-and-hold) → DPO VCO B 1V/Oct Input for varying pitch per hit.
Patch your gate source → DPO Strike Input (Fold snaps to 100% on each gate).
Mult the same gate → Optomix CH 1 Strike Input.
Patch DPO VCO B FINAL → Optomix CH 1 Signal Input.
Set Optomix CH 1 DAMP knob to around 9:00 for a short pluck.
Patch Optomix CH 1 Output → your output.

Signal out Optomix CH 1 Output — a short percussive bongo hit, roughly ±5V, pitched by the random CV.

Listen for A wooden, pitched bongo tone on each gate. Each hit lands on a different note thanks to the random pitch CV; raising Angle toward 3:00 makes the hits more metallic.

▸ Show diagram

Audio-rate Mod Bus injection

Patching an external audio source into Mod Bus External Source replaces VCO A Sine as the Timbre modulator — Shape, Angle, and Fold are driven by your chosen signal at audio rate.

Walkthrough

Tune VCO B FREQ panel control to a bass register (~9:00).
Patch an external audio source (filtered noise, sampler, another VCO's saw) → DPO Mod Bus External Source Input.
Set Shape CV attenuator, Angle CV attenuator, and Fold CV attenuator all to 12:00.
Set Mod Bus Index panel control to around 2:00 for heavy modulation.
Set Shape panel control to 9:00, Angle to 12:00, Fold to 9:00 as a starting timbre.
Patch your sequencer's pitch CV → DPO VCO B 1V/Oct Input.
Patch DPO VCO B FINAL → your output.
Swap the external source to hear how different spectra re-colour Timbre.

Signal out VCO B FINAL — up to 10Vpp, carrying Timbre modulation sourced from the external audio.

Listen for A radically different DPO voice: where internal VCO A Sine gives smooth cross-FM character, external noise crackles Timbre with grit, a sampler imprints rhythmic timbral shifts, and another VCO's saw adds dense sideband harmonics.

▸ Show diagram

DPO as voice + dual modulator

Put VCO A in LFO mode and tap its Sine and Triangle outputs as two phase-related LFOs while VCO B plays the sequence — one module, one voice, two mod sources.

Walkthrough

Press the VCO A Mode button until the LED is Amber (LFO).
Set VCO A FREQ panel control to around 9:00 for slow motion.
Turn Follow panel control full CW — LFO rate tracks VCO B pitch.
Patch your sequencer's pitch CV → DPO VCO B 1V/Oct Input.
Patch DPO VCO A Sine Output → Filter Cutoff CV.
Patch DPO VCO A Triangle Output → VCA CV.
Patch DPO VCO B FINAL → Filter Input.
Patch Filter Output → VCA Input.
Patch VCA Output → your output.

Signal out VCA Output — the sequenced DPO voice, filtered and amplitude-shaped by VCO A's LFO taps.

Listen for A self-modulating voice where filter and VCA breathe in related-but-offset motion, driven entirely from one DPO. Raising VCO A FREQ into low audio range adds chorusing-like amplitude and cutoff wobble per note.

▸ Show diagram

Behaviors

FM Bus (internal sine cross-FM) FM Bus Index above zero

Hardwired Sine-wave bus: VCO A Sine → VCO B Linear/Expo FM AND VCO B Sine → VCO A Linear/Expo FM simultaneously. FM Bus Index is master depth. Per-destination attenuators let you set different FM depths on each VCO. Past ~80% the bus overdrives into bi-directional dynamic FM chaos.

Mod Bus (internal sine → Timbre) Mod Bus Index above zero

Hardwired VCO A Sine → Shape, Angle, Fold CVs. Per-destination unipolar attenuators. Patching a cable to Mod Bus External Source replaces VCO A Sine with that signal as Mod Bus source — audio-rate modulation of Timbre from any external source.

VCO A Lock (Blue LED) Mode button → Blue

Extremely weak phase-sync: VCO A approaches an integer ratio of VCO B and small tuning errors correct. Useful for cleaning up FM patches where VCO A is the modulator. Does not impart audible harmonics.

VCO A Hard Sync (Pink LED) Mode button → Pink

VCO B restarts VCO A's cycle at each B cycle. Introduces strong harmonics. Sweeping VCO A FREQ above VCO B generates classic sync sweeps. Master should be ≥100Hz for best results.

VCO A LFO mode (Amber LED) Mode button → Amber

VCO A becomes an LFO. Routes onto FM and Mod Buses for slow cross-modulation of VCO B. Shape and Angle parameters respond beautifully to VCO A LFO-rate modulation via Mod Bus. Beat-Frequency LED also becomes a tempo indicator.

Follow tracking Follow knob or Follow CV

Determines how well VCO A tracks VCO B 1V/Oct. Full CW: A perfectly follows B (maintains FM/Sync ratios with sequencer). CCW: A is fully independent. Mid settings produce pitch-lag glissandi — 'skronk' effect when a new sequencer note arrives.

Shape vactrol crossfade phase reversal Shape around 12:00

Shape is vactrol-based — slow smooth crossfade. Around the 12:00 region the Shape circuit performs amplitude modulation and phase reversal on its own, causing subtle folding-like behavior before the Fold stage. Use LFO on Shape for subtle timbral animation.

Strike briefly opens Fold gate/clock → Strike

Strike input momentarily snaps Fold to 100% for the duration of the gate. Creates accents, percussive clicks, audio-rate fold modulation. Often multed with a sequencer gate for brightness-per-note.

External Lock on VCO B square/pulse/saw → Ext Lock

Weak phase-reversed sync of VCO B to an external VCO. VCO B approaches integer of external signal. Phase-reversal means summing VCO B + Ext source produces amplitude cancellations dependent on phase — modulating VCO B via Expo CV pushes it out of lock and back.

Fold first 30% acts as VCA Fold knob 0–30%

Below 30%, the Fold circuit behaves like a VCA on the post-Shape/Angle signal — useful for percussive VCA duties without additional modules. Past 30%, folding begins and the circuit loses its VCA character.

Controls

VCO A & VCO B	FREQ (Coarse)	Per-VCO coarse tune. 9.5 octave range · 12Hz – 6kHz
VCO A & VCO B	Fine Tune	Per-VCO fine tune. 1.75 octave range
VCO A & VCO B	Expo Attenuator	Unipolar attenuator for Expo FM input. unipolar
VCO A & VCO B	Linear FM Att	Per-VCO attenuator for Linear FM input. VCO A is uni, VCO B is attenuverter. VCO A: unipolar · VCO B: bipolar
VCO A	VCO A Mode Button	Cycles VCO A core behavior. No LED: Standard · Blue: Lock to B · Pink: Hard Sync to B · Amber: LFO
Interaction	Follow	Determines how much VCO A tracks VCO B's 1V/Oct. Becomes attenuator when Follow CV is patched. CW: full lag-free follow · CCW: independent · combo pot
FM Bus	FM Bus Index	Master depth of internal FM bus (sine-FM in both directions). Index LED shows value. unipolar · overdrives >80%
FM Bus	FM Bus Index CV Att	Bipolar attenuator for FM Bus Index CV. bipolar
VCO B Timbre	Shape	Morphs waveform feeding the Fold circuit. Crossfades via vactrol — slow/smooth. CCW: Sine · 12:00: Spike · CW: Glitched Triangle · phase-reversal window ~12:00
VCO B Timbre	Shape CV Att	Unipolar attenuator for Shape CV. Normalled to Mod Bus. unipolar
VCO B Timbre	Angle	Tilts added harmonics to one end of the wave-cycle. Asymmetric folding. unipolar
VCO B Timbre	Angle CV Att	Unipolar attenuator for Angle CV. Normalled to Mod Bus. unipolar
VCO B Timbre	Fold	Wavefolder depth. First 30% acts as VCA; past 30% introduces fold thresholds. unipolar · VCA-like 0-30% then fold
VCO B Timbre	Fold CV Att	Unipolar attenuator for Fold CV. Normalled to Mod Bus. unipolar
Mod Bus	Mod Bus Index	Master depth of Mod Bus (Sine from VCO A to Shape/Angle/Fold). Index LED shows value. unipolar
Mod Bus	Mod Bus Index CV Att	Bipolar attenuator for Mod Bus Index CV. bipolar

I/O

IN · 15

VCO A Expo bipolar · 10V CV

Exponential FM CV. Normalled to FM Bus.
VCO A 1V/Oct ±5V CV

Pitch CV.
VCO A Linear FM 10V · AC coupled AUDIO

AC-coupled Linear FM. Normalled to FM Bus.
VCO B Expo bipolar · 10V CV

Exponential FM CV. Normalled to FM Bus.
VCO B 1V/Oct ±5V CV

Pitch CV.
VCO B Linear FM 10V · AC coupled AUDIO

AC-coupled Linear FM. Normalled to FM Bus.
VCO B External Lock 10Vpp GATE

Phase-reversed weak sync to external VCO. Use square/pulse/saw.
Follow CV 0V – 5V CV

CV over Follow amount. Follow knob becomes attenuator when patched.
FM Bus Index CV ±4V CV

CV for FM Bus depth.
Shape CV 0V – 5V CV

Unipolar CV for Shape. Normalled into Mod Bus.
Angle CV 8V range CV

Bipolar CV for Angle. Normalled into Mod Bus.
Fold CV 0V – 8V CV

Unipolar CV for Fold. Normalled into Mod Bus.
Mod Bus External Source ±8V AUDIO

Interrupts VCO A Sine as Mod Bus source. Replaces internal routing.
Mod Bus Index CV ±4V CV

CV for Mod Bus depth.
Strike 8V – 10V gate GATE

Briefly opens Fold circuit to 100%. Gate/clock input.

OUT · 6

VCO A Triangle 10Vpp CV

Tapped from triangle core — good for Shape modulation and Hard Sync source.
VCO A Sawtooth 9Vpp AUDIO

Core saw. More aggressive than Triangle/Sine for FM and filter input.
VCO A Sine 10Vpp AUDIO

Sine shaped from triangle core. Default Mod Bus source.
VCO B Sine 10Vpp AUDIO

Sine shaped from triangle core.
VCO B Square 9Vpp asymmetrical AUDIO

Asymmetrical square. Use for External Lock chain or subtractive patches.
VCO B FINAL 10Vpp max AUDIO

Full Timbre-section output — post Shape, Angle, Fold. Main musical output.

Patch Ideas · 10

Behaviors

Controls

I/O

▸ IN · 15

◂ OUT · 6

IN · 15

OUT · 6