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 #20 — complete it first for the best experience
Session 21: Lead Sound Design
Session 21: Lead Sound Design
Objective: Build a cutting, expressive lead patch from scratch with VCO B detuning, filter resonance, and wave folding for edge.
The secret to this lead is VCO A saw + VCO B slight detune (PITCH slightly off noon) through BP2 with moderate resonance (~35%). The bandpass cuts lows and highs, leaving a focused, vocal mid-range presence that cuts through any mix.
Sound Design Strategy: Lead
A lead patch must cut through a mix and respond expressively to playing. Cutting through means occupying a focused frequency range with enough harmonic presence to stand out against pads and bass. Expressiveness means the sound changes with velocity, note length, and register.
Key techniques: detuned oscillators for thickness (two oscillators slightly out of tune create a natural chorus), bandpass or resonant low-pass filtering for mid-range focus, moderate attack time so notes have a slight "swell" that draws the ear, and wave folding for harmonic edge that adds overtones without the harshness of distortion.
Warm-Up (2 min)
Remove all cables. Set all knobs and sliders to noon/center. Play a MIDI note -- you should hear the normalled default tone. Set VCO A OCTAVE to 2, Mixer SAW to ~70%, SUB to ~45% -- recall the bass setup from Session 20. Return to noon/center.
Building the Patch
Cables for this patch:
| # | From | To | Purpose | Overrides |
|---|---|---|---|---|
| 1 | VCO B TRIANGLE OUT | MIXER IN 2 | Blend detuned VCO B into mix | VCO A SINE normalling on IN 2 |
VCO A
- OCTAVE: 4 (lead range)
- PITCH: noon
- PW: ~60% (slightly asymmetric for brightness)
- PW MOD: ~20% (subtle LFO chorus)
- INDEX: ~15% (subtle FM adds harmonic shimmer)
- TZFM/EXP: TZFM
- AC/DC: AC
VCO B
- OCTAVE: 4 (same as VCO A)
- PITCH: slightly sharp of noon (~52%, about +3 cents detune)
- PITCH SOURCE: PITCH A+B (tracks keyboard)
- VCO/LFO: VCO
Mixer
- SAW: ~55% (VCO A saw, primary)
- IN 2: ~40% (VCO B triangle, blended -- Cable 1 overrides VCO A SINE normalling)
- All other sliders: 0%
VCF
- FREQ: ~45%
- Q: ~35% (resonant presence)
- MODE: BP2 (bandpass for focused mid-range)
- LEVEL: ~55%
- FM 1: ~45% (envelope bite on attack)
- FM 2: noon (keyboard tracking)
- FM 3: 0%
Envelope B (filter)
- Attack: ~5%
- Decay: ~35%
- Sustain: ~25%
- Release: ~20%
Envelope A (amplitude)
- Attack: ~5% (slight swell)
- Decay: ~30%
- Sustain: ~70%
- Release: ~20%
- ENVELOPE SPEED: Fast
- HOLD POSITION: Off
- CTRL SOURCE: Level
VCA A
- LEVEL: ~35%
- LEVEL MOD: ~60%
- AUX IN: 0%
Wave Folder
- FOLD: ~20% (harmonic edge)
- MOD: 0%
LFO
- RATE: ~25% (for PWM drift)
Output Control
- MAIN DRIVE: noon
- MAIN LEVEL: ~50%
Step-by-step build:
- Set VCO A OCTAVE to 4, Mixer SAW to ~55%. Play notes -- clean sawtooth lead
- Patch Cable 1: VCO B TRIANGLE OUT -> MIXER IN 2. Set Mixer IN 2 to ~40%. Set VCO B OCTAVE to 4, PITCH slightly sharp of noon. Play a note -- you should hear a thicker, chorused tone from the two slightly detuned oscillators
- Set VCF MODE to BP2, FREQ to ~45%, Q to ~35%. Play notes -- the tone narrows to a focused, vocal mid-range. The bandpass cuts low mud and high harshness, leaving just the cutting lead frequencies
- Set VCF FM 1 to ~45%, Envelope B: Attack ~5%, Decay ~35%, Sustain ~25%, Release ~20%. Play notes -- each note has a filter "bite" on attack that adds presence and articulation
- Set Envelope A: Attack ~5%, Decay ~30%, Sustain ~70%, Release ~20%. The slight attack swell gives the lead a singing quality rather than a harsh onset
- Set Wave Folder FOLD to ~20%. Play notes -- harmonic overtones add edge and presence. The wave folder gives the lead a complex, slightly aggressive character that helps it cut through
- Set VCO A INDEX to ~15% for subtle FM shimmer. Set PW to ~60%, PW MOD to ~20%, RATE to ~25% for gentle pulse width movement on the underlying sawtooth
Playing Tips
- This lead responds well to velocity -- softer playing for mellow phrases, harder strikes for cutting accents
- The BP2 filter with resonance creates a vocal quality that responds to FREQ changes -- sweep FREQ during performance for a "wah" effect
- Play legato (overlapping notes) for smooth, singing phrases. Play staccato for punchy, rhythmic leads
- Highest expressiveness is in the C4-C6 range where the bandpass resonance is most present
Variations
- Screaming lead: Raise Q to ~55% and FM 1 to ~65% for an aggressive, resonant attack
- Mellow lead: Switch MODE to LP2, lower FOLD to 0%, reduce Q to ~15% for a smoother, warmer character
- Sync lead: Set VCO A SYNC TYPE to Hard. Sweep VCO A PITCH or OCTAVE for classic hard sync timbral sweeps
Output Checklist
- Lead patch built with VCO B detuning for thickness
- BP2 filter with resonance provides focused mid-range presence
- Wave folding adds harmonic edge without harshness
- Patch documented in patches/cascadia/searing-lead-recipe.md with full cable routing and knob settings
- Session logged in Obsidian daily note
Key Takeaways
- Lead patches need mid-range focus (bandpass filtering) and harmonic edge (wave folding) to cut through a mix
- Detuning VCO B against VCO A creates natural thickness and chorusing from two analog oscillators
- A slight attack swell (~5%) on both amplitude and filter envelopes gives a singing, expressive quality
Next Session Preview
Session 22 builds an evolving pad -- slow, lush, textured. LFO modulation on filter and PWM creates movement, long envelopes create swells, and optional S&H drift adds unpredictability.