QPAS

Make Noise 18HP
VCF FILTER VCA EFFECTS

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Quad Peak Animation System. Four analog state-variable filter cores sharing FREQ and Q, spread stereo-pairwise by Radiate-L/R. LP, BP, HP and Smile-Pass outputs. Pre-filter VCA on input. Pingable.

Patch Ideas · 10

★ Stereo Radiate animation
Mono VCO through QPAS with opposing Radiate modulation — one LFO spreads the Left peaks outward while the Right peaks close inward, creating a ping-pong stereo image from a mono source.
Walkthrough
  1. Patch your VCO's saw out → QPAS L(Mono) Input. Leave R Input unpatched (it normals from L).
  2. Turn Level combo pot full CW (unity gain) so the VCA is wide open.
  3. Set FREQ to about noon and Q to noon — full, ringing peaks without pinging.
  4. Set Radiate-L panel control to noon and Radiate-R panel control to noon (peaks start at FREQ).
  5. Turn the Radiate-L CV attenuverter full CW (positive) and the Radiate-R CV attenuverter full CCW (inverted).
  6. Patch a slow LFO (~0.5 Hz, ±5V triangle) → QPAS Radiate-L CV Input. The Radiate-R CV Input is normalled to it — one cable, both sides modulated.
  7. Patch QPAS LP L → Mixer In L and QPAS LP R → Mixer In R.
Signal out QPAS LP L and LP R — stereo audio at modular level (±5V). Each side carries two resonant low-pass peaks moving in opposite directions.
Listen for A wide stereo filter-sweep that rocks left-right. As the LFO rises, Left peaks spread outward while Right peaks converge on FREQ — the timbre opens on one side while it tightens on the other. Push Q toward 1 o'clock for more obvious motion.
▸ Show diagram
Patch diagramPatch diagram with 4 modules and 4 connections. Modules: QPAS, VCO, LFO, Mixer. Signals: 3 audio, 1 cv.QPASVCOLFOMixerQ: ~noonRadiate-L att: CWRadiate-R att: CCW (inverted)L InputaudioRadiate-L CV IncvLP LaudioLP RaudioSawaudioOutcvLaudioRaudio11. normalled to Raudiocv
★ Pinged melody
No VCO needed — triggers into the audio input ping the filter's resonance at the currently-set FREQ, producing a kalimba-like melody purely from QPAS self-ringing.
Walkthrough
  1. Set Q to 11:00 or a touch higher — the manual's pinging threshold.
  2. Set Level combo pot to about 2 o'clock so triggers arrive hot enough to excite the peaks.
  3. Set FREQ to a comfortable musical range (~noon).
  4. Turn Radiate-L and Radiate-R panel controls full CCW for a simpler single-pitch ping (manual recommendation).
  5. Patch your sequencer's gate/trigger out → QPAS L(Mono) Input.
  6. Patch the sequencer's pitch CV → QPAS FREQ2 CV Input (un-attenuated, tracks cleanly).
  7. Patch QPAS LP L → your output or mixer.
  8. Play the sequence — tune FREQ until the plucks sit on a musical octave.
Signal out QPAS LP L — percussive resonant pings at modular level, pitch following FREQ2 CV.
Listen for A dry, wooden kalimba/mbira pluck on each trigger, pitched by the sequence. Turning Q toward 1 o'clock lengthens the decay; nudging Radiate open adds a chorus-like detuned pluck pair.
▸ Show diagram
Patch diagramPatch diagram with 3 modules and 3 connections. Modules: QPAS, Sequencer, Output. Signals: 1 audio, 1 pitch, 1 trigger.QPASSequencerOutputQ: ~11:00+FREQ: musical rangeRadiate-L/R: full CCWL InputtrigFREQ2 CV In1v/octLP LaudioGatetrigPitch1v/octInaudio11. pingsaudiopitchtrigger
Pre-filter VCA pluck
Use QPAS's built-in exponential VCA (the Level section) instead of a dedicated VCA. A linear MATHS envelope hitting the expo VCA snaps into a hyper-percussive pluck.
Walkthrough
  1. Patch your VCO's saw → QPAS L(Mono) Input.
  2. Set Level combo pot to noon — it attenuates the Level CV to about half depth.
  3. Set FREQ to noon and Q to about 11:00 for a slightly resonant character.
  4. Patch the sequencer's pitch CV → VCO V/Oct.
  5. Patch the sequencer's gate → MATHS CH 1 Trigger.
  6. On MATHS, set CH 1 Rise near 0 and CH 1 Fall to ~9-10 o'clock (short decay), CH 1 attenuverter full CW.
  7. Patch MATHS CH 1 Variable Out 1 → QPAS Level CV Input.
  8. Patch the sequencer's pitch CV → QPAS FREQ2 CV Input so FREQ tracks the note.
  9. Patch QPAS LP L → output.
Signal out QPAS LP L — plucky filtered VCO notes, no external VCA needed.
Listen for Each gate produces a snappy, exponentially-shaped pluck with filter colour baked in. Lower the Level combo pot for a squashier attack; raise Q toward 1 o'clock to add resonant bite.
▸ Show diagram
Patch diagramPatch diagram with 5 modules and 6 connections. Modules: QPAS, VCO, Sequencer, CH 1, Output. Signals: 2 audio, 1 cv, 2 pitch, 1 trigger.QPASVCOSequencerCH 1OutputLevel: ~noonFREQ: ~noonQ: ~11:00short decayL InputaudioLevel CV IncvFREQ2 CV In1v/octLP LaudioV/Oct1v/octSawaudioPitch1v/octGatetrigTrigtrigVariable Out 1cvInaudioaudiocvpitchtrigger
Feedback distortion
Patch QPAS's own BP output back into FREQ1 CV — the filter self-modulates its cutoff from its own resonance, producing a range of aggressive overdrive tones from a single VCO.
Walkthrough
  1. Patch your VCO's saw → QPAS L(Mono) Input.
  2. Set Level combo pot full CW (unity) and Q to about noon.
  3. Set the FREQ1 CV Input attenuverter to roughly 9 o'clock (small negative amount) to start — it's the distortion depth knob.
  4. Patch QPAS BP R → QPAS FREQ1 CV Input (the feedback loop).
  5. Since R outputs are normalled from L, unplugging/plugging BP R changes the stereo split as a side effect — leave it patched.
  6. Patch QPAS LP L → output.
  7. Slowly sweep the FREQ1 attenuverter from CCW through CW — character shifts from clean to liquid-metal to decayed-rust (manual's words).
  8. Adjust Q and Radiate-R for additional overdrive character.
Signal out QPAS LP L — overdriven, self-modulating filtered VCO at modular level.
Listen for The clean VCO turns into a growling, howling filter voice. Small FREQ1 attenuator settings give buttery saturation; pushing further yields snarling, almost broken-sounding drive. Radiate-R changes the spectral flavour of the distortion.
▸ Show diagram
Patch diagramPatch diagram with 3 modules and 3 connections. Modules: QPAS, VCO, Output. Signals: 2 audio, 1 cv.QPASVCOOutputQ: ~noonFREQ1 att: start ~9 o'clock, sweepL InputaudioFREQ1 CV IncvBP RcvLP LaudioSawaudioInaudio11. feedback overdriveaudiocv
Smile Pass subtle processing
Send a stereo bus through QPAS's Smile Pass outputs for gentle tone-shaping that doesn't duck the mix — SP keeps amplitude roughly constant as FREQ sweeps, unlike LP or HP.
Walkthrough
  1. Patch Mixer Send L → QPAS L(Mono) Input and Mixer Send R → QPAS R Input (break the R normalization for true stereo).
  2. Set Level combo pot full CW for unity gain.
  3. Set Q to about 10 o'clock — light animation, not obvious resonance.
  4. Set FREQ to noon.
  5. Patch a slow LFO (~0.1 Hz) → QPAS FREQ1 CV Input.
  6. Set the FREQ1 attenuverter to about 10 o'clock — shallow, slow cutoff drift.
  7. Patch QPAS SP L → Output L and QPAS SP R → Output R (SP outputs are stereo-only and NOT normalled — use both, never one).
  8. Listen to the return; the level stays stable while timbre breathes.
Signal out QPAS SP L and SP R — stereo filtered bus at approximately unity output level, regardless of FREQ position.
Listen for A gentle, breathing tonal sweep across a drum bus or pad without the usual "kick disappears when cutoff drops" problem. More texture than effect. Push Q up for more obvious coloration.
▸ Show diagram
Patch diagramPatch diagram with 4 modules and 5 connections. Modules: QPAS, LFO, Mixer, Output. Signals: 4 audio, 1 cv.QPASLFOMixerOutputQ: ~10:00FREQ1 att: ~10 o'clockL InputaudioR InputaudioFREQ1 CV IncvSP LaudioSP RaudioOutcvSend LaudioSend RaudioLaudioRaudioaudiocv
Spectral crossfader
Two voices, one FREQ knob: the Left cores LP one voice while the Right cores HP the other. Turning FREQ crossfades spectrally between them.
Walkthrough
  1. Patch VCO A → QPAS L(Mono) Input.
  2. Patch VCO B → QPAS R Input (breaks the R-from-L normal so each side gets its own source).
  3. Set Level combo pot full CW, Q low (~9-10 o'clock), Radiate-L and Radiate-R at noon.
  4. Patch QPAS LP L → Mixer CH 1.
  5. Patch QPAS HP R → Mixer CH 2.
  6. Turn the FREQ knob fully CCW — LP keeps VCO A audible, HP attenuates VCO B.
  7. Turn FREQ fully CW — the balance inverts: VCO A is now filtered out, VCO B passes.
  8. Optional: patch a slow LFO → FREQ2 CV Input for automated crossfading.
Signal out Mixer output — morph between VCO A (LP-filtered on L side) and VCO B (HP-filtered on R side), driven by FREQ.
Listen for As FREQ sweeps low to high, the first voice fades out as the second fades in, with a spectral overlap zone around cutoff. Very different from a standard crossfader — it's frequency-dependent, not amplitude-only.
▸ Show diagram
Patch diagramPatch diagram with 4 modules and 4 connections. Modules: QPAS, VCO A, VCO B, Mixer. Signals: 4 audio.QPASVCO AVCO BMixerQ: low (~9-10 o'clock)L InputaudioR InputaudioLP LaudioHP RaudioOutaudioOutaudioCH 1audioCH 2audioaudio
!!¡¡ accent bursts
Route the sequencer gate to both an envelope AND QPAS's !!¡¡ input — each note fires a percussive resonance kick on top of the normal filtered tone, a manual-documented use of the !!¡¡ excitation input.
Walkthrough
  1. Patch VCO saw → QPAS L(Mono) Input.
  2. Set Q to about 2 o'clock (peaks emphasized, per the manual's "pump up" guidance).
  3. Set FREQ to noon, Level combo pot to noon.
  4. Patch the sequencer's gate → a passive multiple.
  5. From the mult: one cable → Envelope (Trig), second cable → QPAS !!¡¡ Input (either of the two !!¡¡ jacks).
  6. Patch the Envelope Out → QPAS Level CV Input — this opens the VCA per note.
  7. Patch QPAS LP L → output.
  8. Play the sequence — each gate plays the note AND flicks the !!¡¡ bus for an extra resonant accent.
Signal out QPAS LP L — envelope-gated filter notes with per-note resonance accents injected via !!¡¡.
Listen for Normal filtered VCO notes with an extra chirpy/resonant "flick" layered on the attack of each note. Swap the !!¡¡ trigger source for an audio-rate signal and the accents become clangorous cross-modulation.
▸ Show diagram
Patch diagramPatch diagram with 6 modules and 6 connections. Modules: QPAS, VCO, Sequencer, Mult, Envelope, Output. Signals: 2 audio, 1 cv, 2 gate, 1 trigger.QPASVCOSequencerMultEnvelopeOutputQ: ~2:00FREQ: ~noonL Inputaudio!!¡¡ IntrigLevel CV IncvLP LaudioSawaudioGategateIngateOut 1gateOut 2trigTriggateOutcvInaudioaudiocvgatetrigger
Transient resonator (Morphagene)
Straight from the manual — feed Morphagene stereo out to QPAS stereo in, and patch Morphagene's CV Out to QPAS Q CV so each tape transient swells the resonance into a ringing tail.
Walkthrough
  1. Patch Morphagene Out L → QPAS L(Mono) Input and Morphagene Out R → QPAS R Input.
  2. Set Level combo pot full CW, FREQ below noon (per the manual).
  3. Set Q panel control to about 11:00.
  4. Turn the Q CV Input attenuverter full CW (manual specification).
  5. Patch Morphagene CV Out → QPAS Q CV Input.
  6. Patch QPAS HP L → output (manual uses HP L, not LP — the resonant tails sit above the transient spectrum).
  7. Play a transient-rich reel on Morphagene (clicks, drums, plosives).
  8. Each dynamic spike in the audio raises Q momentarily, ringing the filter.
Signal out QPAS HP L — original high-passed tape audio with resonant tails that bloom on each transient.
Listen for Clicks and snares gain singing tonal tails; sustained material stays relatively dry. The resonance tracks the dynamics of the reel. Sweep FREQ to tune the tails to a musical pitch.
▸ Show diagram
Patch diagramPatch diagram with 3 modules and 4 connections. Modules: QPAS, Morphagene, Output. Signals: 3 audio, 1 cv.QPASMorphageneOutputQ: ~11:00Q CV att: full CWFREQ: below noonL InputaudioR InputaudioQ CV IncvHP LaudioOut LaudioOut RaudioCV OutcvInaudio11. resonant tailsaudiocv
★ Drone cluster
A sine VCO into high-Q QPAS with Radiate opened — four slightly-offset filter peaks ring near the VCO pitch, producing a rich formant-cluster drone from a single oscillator.
Walkthrough
  1. Patch VCO sine → QPAS L(Mono) Input.
  2. Set Level combo pot to 2 o'clock.
  3. Set FREQ to a musical note you want the drone to centre on.
  4. Set Q to about 2 o'clock (high, but QPAS does not self-oscillate — it still needs an input).
  5. Set Radiate-L panel control to ~1 o'clock and Radiate-R to ~11 o'clock — the four peaks fan out around FREQ.
  6. Patch QPAS LP L → Output L and QPAS LP R → Output R.
  7. Optional: sweep FREQ slowly by hand, or patch a very slow LFO → FREQ1 CV Input with the attenuverter near 9 o'clock, for morphing formant chords.
Signal out QPAS LP L / LP R — stereo resonant drone, four detuned peaks clustered around FREQ.
Listen for A thick, vocal-like cluster drone with a stereo width that wasn't in the sine source. Sweeping FREQ walks the chord through different harmonic relationships. Adjust Radiate for tighter unison or wider formant intervals.
▸ Show diagram
Patch diagramPatch diagram with 3 modules and 3 connections. Modules: QPAS, VCO, Output. Signals: 3 audio.QPASVCOOutputQ: ~2:00Radiate-L: ~1 o'clockRadiate-R: ~11 o'clockFREQ: musical noteL InputaudioLP LaudioLP RaudioSineaudioLaudioRaudioaudio
Karplus-ish pluck
Short noise bursts into a high-Q QPAS tuned by pitch CV — the ringing filter acts like the delay line of a Karplus-Strong string, producing plucked tones from noise.
Walkthrough
  1. Patch your noise source → a VCA input.
  2. Patch the sequencer's gate → VCA CV (use a short AD envelope if your VCA doesn't have a built-in gate response).
  3. Patch VCA out → QPAS L(Mono) Input.
  4. Set Level combo pot to noon.
  5. Set Q to about 2 o'clock for a long plucked ring.
  6. Set FREQ to match the pitch range you want (start around noon).
  7. Patch the sequencer's pitch CV → QPAS FREQ2 CV Input (un-attenuated, ~1V/Oct cutoff).
  8. Turn Radiate-L and Radiate-R full CCW for a single, focused pitch per note.
  9. Patch QPAS LP L → output — optionally also LP R for chorused stereo plucks with Radiate opened.
Signal out QPAS LP L — short, pitched, plucked tones derived from noise rung through high-Q filter peaks.
Listen for Each trigger produces a nylon-string-ish pluck pitched by the sequencer. Short VCA gate = tight pluck; longer gate = more airy, string-like attack. Opening Radiate adds a subtle chorus of detuned pluck copies.
▸ Show diagram
Patch diagramPatch diagram with 5 modules and 5 connections. Modules: QPAS, Noise, VCA, Sequencer, Output. Signals: 3 audio, 1 pitch, 1 gate.QPASNoiseVCASequencerOutputQ: ~2:00Radiate-L/R: full CCWL InputaudioFREQ2 CV In1v/octLP LaudioOutaudioInaudioCVgateOutaudioGategatePitch1v/octInaudioaudiopitchgate

Behaviors

Four peaks share one cutoff rotate FREQ

All four filter cores share a single cutoff parameter. FREQ moves the centre of the whole peak cluster. Radiate-L and Radiate-R then spread two peaks each away from that centre — FREQ pans the cluster, Radiate widens it.

Radiate CV normalization patch only Radiate-L CV Input

Radiate-R CV Input is normalled to Radiate-L CV Input. One cable modulates both sides identically when the attenuverters are set the same, or oppositely when one attenuverter is inverted — fast stereo motion from a single LFO.

Output normalization (LP/BP/HP) patch only the Left output of a filter type

Right outputs of LP, BP and HP are normalled to their Left. Patching out of L gives a mono mix of all four peaks. Patching out of R splits the peaks into two pairs (true stereo). Smile Pass is the exception — it is stereo only.

Pingable with high Q Q ≥ 11:00 · trigger → input

Sending gates/triggers into the audio input momentarily opens the filters at their cutoff frequencies, producing plucks/pings with decay set by Q. Sequencing FREQ produces melodic pings. Modulating FREQ with an audio-rate sine yields classic low-pass-gate ping character.

Negative-Q zone Q below ~9:00

Below '0' resonance point (~9:00), QPAS provides 'negative resonance' — filter peaks are actively attenuated rather than accentuated. Combines with FREQ sweeps for unusual ducking/notch-like behaviour not available on most filters.

Exponential pre-filter VCA Level CV with envelope

Level VCA uses exponential response. Linear envelopes (MATHS) produce exponential-VCA shapes — very snappy plucks from short, sharp envelopes. Using Level as a pre-filter VCA often removes the need for a separate VCA module.

!!¡¡ chaotic mod bus clock / gate / audio → !!¡¡ Input

!!¡¡ inputs modulate many internal signals simultaneously. Clocks excite/accent resonance in rhythmic bursts. Audio-rate signals produce cross-modulation chaos. Each input affects two peaks — one from each stereo pair — for asymmetric stereo motion.

Mono-to-stereo from mono input patch only L Input · take L and R of any filter type

L normalled from R gives all four cores the same mono input. Radiate spreads them stereo-wise. Single cable in → stereo filtered output with animated stereo peaks from a mono signal.

Smile Pass constant-amplitude select SP output

Smile Pass topology changes with FREQ to maintain approximately constant output amplitude across the cutoff range. Unlike LP (quiet high, loud low) or HP (opposite), SP keeps level steady — useful for subtle filter effects that don't dramatically duck the mix.

Feedback overdrive via FREQ1 patch BP or HP R out → FREQ1 CV

Feeding a filter output back into FREQ1 CV Input (attenuverted) creates self-modulating overdrive. Combined with Q and Radiate, produces a 'liquid metal to decayed rust' range of distorted filter timbres.

Controls

Global (all four cores) FREQ Base cutoff frequency for every peak of every filter type. Large knob.
audio-range cutoff · shared across all 4 cores
FREQ1 CV FREQ CV Input Attenuverter Sets depth and polarity of FREQ1 CV Input. Bipolar — allows inverted modulation.
bipolar · CCW invert · noon off · CW positive
Global Q Resonance / peak height for all four filter cores. Does not self-oscillate by design. At low settings peaks round; at high settings peaks accentuate and the Radiate controls become more dramatic.
~9:00: 'zero' resonance · CCW: negative (attenuated peaks)
Q Q CV Input Attenuverter Depth and polarity of Q CV.
bipolar
Input VCA Level Combo Pot Pre-filter exponential VCA gain. Acts as attenuator for Level CV when patched. Sets input drive — higher Q + lower Level = resonance exceeding input.
expo response · unity-gain when CW
Left stereo pair Radiate-L Spreads the two Left-channel peaks away from FREQ. Mid = peaks coincide with FREQ; CW or CCW pushes them apart symmetrically.
bipolar · center: peaks at FREQ
Radiate-L Radiate-L CV Attenuverter Depth and polarity for Radiate-L CV. CV Input normalled to Radiate-R CV Input — one cable modulates both unless broken.
bipolar
Right stereo pair Radiate-R Spreads the two Right-channel peaks away from FREQ.
bipolar · center: peaks at FREQ
Radiate-R Radiate-R CV Attenuverter Depth and polarity for Radiate-R CV. Invert one side for opposing stereo motion.
bipolar

I/O

IN · 9

  • L (Mono) Input modular audio AUDIO
    Audio input to the Left cores. When only this is patched, the signal is sent to all four cores.
  • R Input modular audio AUDIO
    Audio input to Right cores. Normalled to L(Mono) Input when unpatched.
    NORM → L(Mono) Input
  • Level CV Input 0V – 8V CV
    CV over input VCA. Attenuated by Level Combo Pot. Exponential response — linear envelopes still produce expo shapes.
  • FREQ1 CV Input ±5V typical CV
    Attenuverted/polarised FREQ CV input.
  • FREQ2 CV Input ±5V typical CV
    Un-attenuated FREQ CV input. Straight 1V/Oct-style cutoff control.
  • Radiate-L CV Input ±5V typical CV
    CV for Radiate-L, attenuverted.
  • Radiate-R CV Input ±5V typical CV
    CV for Radiate-R, attenuverted. Normalled to Radiate-L CV Input.
    NORM → Radiate-L CV Input
  • Q CV Input ±5V typical CV
    CV for resonance, attenuverted.
  • !!¡¡ Inputs (2) gate / audio rate GATE
    Clock, gate or audio-rate modulation inputs that poke nearly every part of the circuit. Each input affects two peaks — one per stereo pair.

OUT · 4

  • LP L / LP R modular audio AUDIO
    Low-Pass filter outputs. Right LP normalled to Left LP — pull only L for sum-of-four-peaks mono.
  • BP L / BP R modular audio AUDIO
    Band-Pass filter outputs. Right BP normalled to Left BP.
  • HP L / HP R modular audio AUDIO
    High-Pass filter outputs. Right HP normalled to Left HP.
  • SP L / SP R modular audio AUDIO
    Smile-Pass outputs. Stereo only — topology changes with cutoff to keep output level relatively constant regardless of FREQ. Not normalled together.