Quick Reference
Cascadia Signal Flow
With no cables patched, the Cascadia produces sound through these normalled connections:
Diagram key: Solid arrows (-->) show the primary audio signal path from oscillator to output. Dashed arrows (-.->) show modulation normalling and secondary connections that shape the sound but are not part of the main audio chain.
What Each Connection Does
Primary Audio Path (solid lines)
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MIDI/CV -> VCO A pitch: MIDI note data sets the pitch of VCO A via 1V/octave CV. This is the main pitch source for the instrument.
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MIDI/CV -> VCO B pitch: MIDI pitch is also normalled to VCO B (when its PITCH SOURCE switch is set to PITCH A+B), keeping both oscillators in tune.
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VCO A -> Mixer: VCO A's waveform outputs (saw, pulse, triangle) feed the Mixer, where they are blended with noise, sub-oscillator, and external inputs.
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Mixer -> VCF: The mixed signal enters the voltage-controlled filter for spectral shaping. Patching into VCF IN overrides this connection.
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VCF -> Wave Folder: The filtered signal passes through the wave folder. Even with folding at minimum, the signal passes through to VCA A.
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Wave Folder -> VCA A: The wave folder output is normalled to VCA A's input, completing the audio chain before the output stage.
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VCA A -> Output Control: VCA A's output is normalled to the MAIN 1 input on Output Control, which drives the headphone and line outputs.
Modulation Normalling (dashed lines)
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Envelope A -> VCA A (CV): Envelope A's output controls VCA A's amplitude. This is the amplitude envelope -- it shapes every note's volume over time (attack, decay, sustain, release). Patching into VCA A's LEVEL MOD IN overrides this.
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Envelope A -> VCO A (IM): Envelope A is normalled to VCO A's Index Modulation input, allowing the envelope to control FM depth. The IM MOD slider sets how much this affects FM 2 intensity.
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Envelope B -> VCF (FM 1): Envelope B modulates the filter cutoff frequency via FM 1. This creates the classic "envelope-controlled filter sweep" heard in plucky and percussive sounds. Patching into VCF FM 1 IN overrides this.
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MIDI/CV -> VCF (FM 2): MIDI pitch is normalled to VCF FM 2, providing keyboard tracking for the filter. This keeps the filter cutoff proportional to the note being played, essential when the filter is self-oscillating.
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MIDI/CV -> Envelope A (velocity): MIDI velocity is normalled to Envelope A's CTRL input. Depending on the CTRL SOURCE switch, this scales either the envelope's amplitude or its overall time -- softer notes play quieter or slower.
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MIDI/CV -> Envelope A (gate): MIDI gate triggers Envelope A. The gate going high starts the attack stage; the gate going low triggers the release stage.
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MIDI/CV -> Envelope B (gate): MIDI gate also triggers Envelope B, so both envelopes respond to the same note events by default.
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VCO B -> VCO A (FM 2): VCO B's sine wave output is normalled to VCO A's FM 2 input. This enables frequency modulation synthesis with zero cables -- use VCO A's INDEX slider to dial in FM depth.
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LFO X/Y -> VCO A (PWM): LFO Y is normalled to VCO A's pulse width modulation input. Raising the PW MOD slider adds movement to the pulse wave output. LFO Z is normalled to MULT IN 1 in the Patchbay for distribution.
This session builds on Session #26 — complete it first for the best experience
Session 27: Partial Recipe -- Modular Drum Hit
Session 27: Partial Recipe -- Modular Drum Hit
Objective: Build a snappy, punchy drum hit using short envelopes, the VCA/LPG, and noise. This session provides the skeleton of the patch -- you fill in the blanks that determine the character of the hit.
Remove all cables. Mixer NOISE ~60% (WHITE). Envelope A: Attack 0%, Decay ~15%, Sustain 0%, Release ~10%, ENVELOPE SPEED Fast. VCF FREQ ~40%, MODE LP2. Trigger a note -- instant snappy hit.
Target Sound
A short, percussive hit with a sharp transient and fast decay. Think electronic snare or hi-hat -- a burst of noise shaped by a fast envelope through a filter. The sound should have a clear attack, a defined body, and stop cleanly. Modular percussion is about envelopes and filters working together at speed.
Starting Patch
Remove all cables. Set all knobs and sliders to noon/center.
Steps
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Set Mixer: NOISE = ~55%, NOISE TYPE =
____(hint: Session 17 covered sample and hold and noise sources -- which noise color has the right spectral content for a crisp percussive hit? Think about what WHITE vs PINK sound like and which cuts through a mix.) -
Set all other Mixer sliders to 0% (pure noise source for the drum hit)
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Set Envelope A: Attack = 0%, Decay =
____, Sustain = 0%, Release = ~8%, ENVELOPE SPEED = Fast (hint: Session 23 built percussion patches -- how short should the decay be for a tight, snappy hit versus a longer, boomy one? The decay length defines whether this is a click, a snare, or a tom.) -
Set VCF MODE = LP2
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Set VCF FREQ = ~40%, Q = ~25%
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Set VCF FM 1 = ~50% (envelope sweeps the filter hard and fast on each hit)
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Set Envelope B: Attack = 0%, Decay = ~20%, Sustain = 0%, Release = ~10%, ENVELOPE SPEED = Fast
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Patch Envelope A ENV OUT -> VCA/LPF B CV IN. Set VCA CONTROL =
____, CV AMOUNT = ~65% (hint: Session 23 used the LPG for percussion -- which VCA CONTROL position gives you the snappiest transient response? Remember the three modes: UP is VCA+LPF, CENTER is VCA only, DOWN is LPF only.) -
Patch LPF B OUT -> MAIN 2 IN to route the VCA/LPG output to the second main output
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Set Wave Folder FOLD = ~10% (adds a slight edge to the transient)
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Trigger single notes rapidly. Each hit should be a clean, defined percussion event with a sharp attack and fast decay.
Variations
After filling in the blanks and getting the basic hit:
- Pitched drum: Add VCO A to the Mixer (SAW ~30%) alongside the noise. The oscillator adds tonal body -- more kick-like or tom-like
- Metallic hit: Raise Wave Folder FOLD to ~35% and Q to ~40% for a harsh, industrial percussion sound
- Longer tail: Double the Envelope A Decay for a more boomy, reverberant hit
Listen For
- A sharp, clean transient on the attack -- the hit should snap, not fade in
- A fast decay that stops cleanly without ringing or tailing off
- The filter sweep adding tonal shape to the noise burst -- brighter at the attack, darker as it decays
- The LPG/VCA adding its characteristic response to the envelope
Reflection
Percussion synthesis strips everything down to the essentials: a noise source, an envelope, and a filter. The three blanks you filled in define the character of the hit -- noise color sets the spectral content, decay length sets the size, and VCA mode sets the transient shape. Compare your drum hit to Session 23's percussion patches. How does yours differ? Try the variations above and note which settings you prefer.
Output Checklist
- Modular drum hit patch completed with all blanks filled in
- Cable routing documented (Env A -> VCA/LPF B, LPF B -> Main 2)
- Parameter values documented with reasoning
- Patch documented in patches/cascadia/ with full knob settings and cable routing
- Session logged in Obsidian daily note