Quadra

Intellijel 12HP
ENVELOPE LFO FUNCTION

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Quad analog function generator. Each channel runs AD, ASR, or Cycle mode with per-channel exponential/linear switch. Optional Quadra Expander adds EOC outs, CV over A/D, analog OR logic outs and Quadrature mode.

Patch Ideas · 6

★ Classic ADSR keyboard voice
CH 1 = AD · CH 2 = ASR · both triggered by keyboard gate · ENV 2 OR attenuator sets sustain · OR 1+2 → VCA CV · one-knob sustain control with true ADSR shape
▸ Show diagram
Patch diagramPatch diagram with 6 modules and 4 connections. Modules: Quadra, Keyboard, Quadra Expander, VCA, VCO, VCA (In) -> Output. Signals: 1 audio, 1 cv, 2 gate.QuadraKeyboardQuadra ExpanderVCAVCOVCA (In) -> OutputCH 1: AD mode · linearCH 2: ASR mode · linearExpander: ENV 2 OR atten = sustain levelTRIG 1gateTRIG 2gateGategateOR 1+2cvCVcvOutaudioInaudioaudiocvgate
★ Kick drum (West Coast)
Sine VCO → VCA 2 · CH 1 AD (fast A, med D) → VCO pitch CV via attenuator (pitch sweep) · CH 2 AD (fast A, slightly shorter D) → VCA CV (amp) · both triggered from sequencer · snappy boomy kick
▸ Show diagram
Patch diagramPatch diagram with 6 modules and 7 connections. Modules: Quadra, VCO, VCA, Attenuator, Sequencer, Output. Signals: 2 audio, 2 cv, 1 pitch, 2 trigger.QuadraVCOVCAAttenuatorSequencerOutputCH 1: AD · exp · fast A, medium DCH 2: AD · exp · pitch decay < amp decayTRIG 1trigTRIG 2trigENV 1cvENV 2cvFM1v/octSineaudioInaudioCVcvOutaudioIncvOut1v/octTrigtrigInaudioaudiocvpitchtrigger
★ Quadrature LFO pair
QUAD 1+2 switch ON · CH 1 + CH 2 in AD mode, short A and D · OR 1+2 → complex looping LFO shape · ENV 1 and ENV 2 individually drive two filter cutoffs for stereo motion that never phases together identically
▸ Show diagram
Patch diagramPatch diagram with 5 modules and 3 connections. Modules: Quadra, Filter L, Filter R, Quadra Expander, VCA. Signals: 3 cv.QuadraFilter LFilter RQuadra ExpanderVCACH 1: AD · CH 2: ADExpander: QUAD 1+2 ONENV 1cvENV 2cvCutoffcvCutoffcvOR 1+2cvCVcv11. complex composite shapecv
Chained four-stage envelope
CH 1 AD · EOC 1 → TRIG 2 · CH 2 AD · EOC 2 → TRIG 3 · continue through CH 4 · single trigger fires four sequential envelopes to four destinations (filter, VCA, pan, wavefolder)
▸ Show diagram
Patch diagramPatch diagram with 7 modules and 8 connections. Signals: 4 cv, 4 trigger.QuadraSequencerQuadra ExpanderFilterVCAPanWavefolderCH 1-4: ADTRIG 1trigTRIG 2trigTRIG 3trigTRIG 4trigENV 1cvENV 2cvENV 3cvENV 4cvTrigtrigEOC 1trigEOC 2trigEOC 3trigCutoffcvCVcvCVcvFoldcvcvtrigger
Self-cycling kick with ducking
CH 1 Cycle mode (A+D = tempo) = tempo clock · CH 2 AD fires envelope on each EOC 1 pulse · CH 2 → inverter → bass VCA CV for sidechain ducking against the self-cycling kick on CH 1
▸ Show diagram
Patch diagramPatch diagram with 7 modules and 6 connections. Signals: 2 audio, 3 cv, 1 trigger.QuadraQuadra ExpanderKick VCAInverterBass VCAKick VCOBass VCOCH 1: CYCLE · A+D = tempoCH 2: AD · longer DTRIG 2trigENV 1cvENV 2cvEOC 1trigCVcvInaudioIncvOutcvCVcvInaudioOutaudioOutaudioaudiocvtrigger
Internal A/D CV sweep
CH 3 Cycle as slow LFO · ENV 3 → CH 1 A CV (Expander · unpatched D CV normals through) · as LFO rises, both attack and decay of CH 1 lengthen together — envelope on CH 1 gets progressively lazier over minutes
▸ Show diagram
Patch diagramPatch diagram with 4 modules and 3 connections. Modules: Quadra, Sequencer, Quadra Expander, VCA. Signals: 2 cv, 1 trigger.QuadraSequencerQuadra ExpanderVCACH 1: AD · CH 3: CYCLE (very slow)TRIG 1trigENV 3cvENV 1cvTrigtrigA CV 1cvCVcv11. D CV normals from A CVcvtrigger

Behaviors

AD mode TRIG input

One-shot AD envelope, completes full cycle regardless of gate length. Ideal for sequencer-driven percussive and pluck envelopes.

ASR mode gate at TRIG

Attack on gate rise, sustains at peak while gate is high, releases on gate fall. Used for keyboard-style voices where note length matters.

Cycle mode mode switch → Cycle

AD loops continuously as a unipolar LFO. Total rate = Attack + Decay times. No trigger required; TRIG input still resets phase.

ADSR via OR output CH 1 = AD · CH 2 = ASR · both triggered by same gate → OR 1+2

Triggering an AD and ASR channel simultaneously produces an ADSR shape at the OR output. ENV 2 OR attenuator sets sustain level. Fabricates classic ADSR from two Quadra channels.

Quadrature mode QUAD 1+2 switch ON (Expander)

CH 1 self-cycles via its own EOC. CH 2 triggers on CH 1's end-of-attack but won't decay until CH 1 finishes its decay. Creates phase-shifted looping envelopes; great for OR-mixed complex LFO shapes.

A/D CV normal unpatched D CV jack (Expander)

Attack CV jack is normalized to Decay CV — patching to A CV only modulates both attack and decay together. Patching D CV breaks the normal for independent control.

Linear mode speeds up exp/lin switch → Linear

Linear curves permit the fastest envelope times. Exponential mode produces classic VCA-friendly percussive curves but has a speed floor.

Controls

CH 1–4 ATTACK Attack time — rise from zero to peak. CCW = fastest. Fastest times achieved in linear mode.
0.5ms – 30s+
CH 1–4 DECAY Decay/release time. In AD mode = fall-to-zero · in ASR = release after gate · in Cycle = sum with Attack sets LFO rate.
0.5ms – 30s+
CH 1–4 Exp / Linear switch Selects curve shape. Linear = straight ramps · Exponential = classic percussive curve. Linear mode permits fastest envelope times.
Per-channel toggle
CH 1–4 Mode switch (AD / ASR / Cycle) AD = one-shot on trigger (ignores gate length). ASR = attack/sustain/release following the gate. Cycle = AD loops as unipolar LFO.
Three-position slide switch
CH 1–4 Amplitude LED Visual indicator of each channel's current envelope level.
Brighter = higher amplitude
CH 1–4 · requires Quadra Expander A CV attenuator (Expander) Attenuates the Attack CV input for the channel. Normalized to the D CV attenuator so one CV can control both.
Unipolar attenuator
CH 1–4 · requires Quadra Expander D CV attenuator (Expander) Attenuates the Decay CV input for the channel.
Unipolar attenuator
CH 1+2 pair · requires Expander QUAD 1+2 switch (Expander) Engages Quadrature mode for 1+2. CH 1's end-of-attack triggers CH 2. Creates interdependent looping envelopes that resemble 90°-shifted waveforms.
On/off
CH 3+4 pair · requires Expander QUAD 3+4 switch (Expander) Engages Quadrature mode for 3+4.
On/off
OR 1+2 / OR 3+4 · requires Expander OR amount (ENV 2 / ENV 3) Sets how much of ENV 2 (or ENV 3) is summed into the OR 1+2 (or OR 3+4) output. Used to dial sustain level when constructing ADSR from AD+ASR pairs.
Unipolar attenuator

I/O

IN · 3

  • TRIG 1–4 gate GATE
    Gate/trigger input per channel. Triggers AD, gates ASR, resets/syncs Cycle.
  • A CV 1–4 (Expander) CV CV
    Voltage control of attack time. Normalized to D CV jack of same channel.
    NORM → D CV of same channel
  • D CV 1–4 (Expander) CV CV
    Voltage control of decay time.

OUT · 4

  • ENV 1–4 0–8V ENV
    Per-channel function output, unipolar
  • EOC 1–4 (Expander) gate GATE
    End-of-Cycle gate — high when the channel completes its decay phase
  • OR 1+2 (Expander) 0–8V ENV
    Analog OR (peak) of ENV 1 and ENV 2 (ENV 2 scaled by OR amount). Used to fabricate ADSR shapes.
  • OR 3+4 (Expander) 0–8V ENV
    Analog OR (peak) of ENV 3 and ENV 4 (ENV 3 scaled by OR amount)