Session 23: Percussion Sound Design

Objective: Build a complex, multi-layered percussion patch combining the LPG, ring modulation, noise, and multiple envelope shapes for a rich drum sound that goes beyond the basic bongo.

Sound Design Strategy: Percussion

Great synthesized percussion layers multiple timbral elements: a body (pitched oscillator through an LPG for the fundamental thump), a transient (noise burst for the initial click/snap), and character (ring modulation, FM, or wave folding for metallic or tonal color). Each element has its own envelope shape -- the transient is fastest, the body slightly longer, the character somewhere in between.

The LPG is the foundation because its coupled amplitude-filter response creates naturally musical percussion dynamics. Layering noise and ring mod on top adds the complexity that separates a synthesized drum from a basic bleep.

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 Envelope A to Attack ~0%, Decay ~20%, Sustain ~0%, ENVELOPE SPEED Fast -- recall the percussive envelope from Session 12. Return to noon.

Building the Patch

Cables for this patch:

VCO A

• OCTAVE: 3 (percussion range)
• PITCH: noon
• INDEX: ~10% (subtle FM adds metallic overtones)
• TZFM/EXP: TZFM
• AC/DC: AC

VCO B

• OCTAVE: 5 (high ratio for metallic FM sidebands)
• PITCH SOURCE: PITCH A+B
• VCO/LFO: VCO

Mixer

• SAW: ~35% (blended into main path for transient layer)
• NOISE: ~25% (noise click transient)
• NOISE TYPE: PINK (warmer noise for percussion)
• IN 1: ~20% (ring mod metallic character)
• All other sliders: 0%

VCF

• FREQ: ~55%
• Q: ~10%
• MODE: LP4
• LEVEL: ~50%
• FM 1: ~55% (sharp envelope sweep on main path)
• FM 2: noon
• FM 3: 0%

Envelope B (filter on main path)

• Attack: ~0%
• Decay: ~20%
• Sustain: ~0%
• Release: ~10%

Envelope A (LPG percussion -- routed via Cable 2)

• Attack: ~0%
• Decay: ~25%
• Sustain: ~0%
• Release: ~10%
• ENVELOPE SPEED: Fast
• HOLD POSITION: Off
• CTRL SOURCE: Level

VCA B / LPF

• CV AMOUNT: ~80%
• VCA CONTROL: UP (LPG mode)

VCA A

• LEVEL: ~25%
• LEVEL MOD: ~50%
• AUX IN: 0%

Wave Folder

• FOLD: ~15% (slight harmonic crunch)
• MOD: 0%

Output Control

• MAIN DRIVE: noon
• MAIN LEVEL: ~50%

Step-by-step build:

1. Set VCO A OCTAVE to 3. Set Mixer SAW to ~35%, NOISE to ~25%, NOISE TYPE to PINK, IN 1 to ~20%
2. Set Envelope B: Attack ~0%, Decay ~20%, Sustain ~0%, Release ~10%. Set VCF FM 1 to ~55%, FREQ to ~55%, MODE LP4. Play a note -- you should hear a short, snappy filtered hit with a noise click and subtle ring mod character in the main path
3. Patch Cable 1: VCO A SAW OUT -> VCA B IN. Patch Cable 2: Envelope A ENV OUT -> VCA/LPF B CV IN. Set VCA CONTROL to UP (LPG mode), CV AMOUNT to ~80%

4. Set Envelope A: Attack ~0%, Decay ~25%, Sustain ~0%, Release ~10%, ENVELOPE SPEED Fast. Play a note -- the LPG produces the woody bongo percussion from Session 12
5. Patch Cable 3: LPF B OUT -> MAIN 2 IN. Now the LPG output sums with the main signal path at the output. Play a note -- you should hear both the main path (filtered sawtooth + noise + ring mod) AND the LPG percussion simultaneously. The result is a complex, layered drum hit
6. Set VCO A INDEX to ~10%, VCO B OCTAVE to 5. The FM adds metallic shimmer to the sawtooth before it enters the LPG, giving the percussion a tonal complexity beyond a simple bongo
7. Set VCA A LEVEL to ~25%, LEVEL MOD to ~50%. This controls the main path contribution. Adjust the balance between main path (noise + ring mod transient) and LPG (woody body) by tweaking MAIN LEVEL vs Cable 3's signal level at the output
8. Set Wave Folder FOLD to ~15%. The main path gets a slight harmonic crunch that adds aggression to the transient layer

Playing Tips

• Play staccato notes at C2-C4 for the best percussion response. Lower notes produce deeper drums; higher notes produce more metallic clicks
• Velocity controls the LPG strike intensity (CTRL SOURCE at Level) -- soft taps for ghost notes, hard strikes for accents
• Rapid rhythmic playing creates convincing drum patterns. Try alternating C2 and C3 for a kick/snare-like pattern
• Experiment with VCO A OCTAVE: position 2 for kick-like thuds, position 4 for snare-like snaps

Variations

• Deeper kick: Lower VCO A OCTAVE to 2, set Mixer NOISE to 0%, IN 1 to 0%. Pure LPG body with no transient layers
• Metallic hit: Raise INDEX to ~30% and VCO B OCTAVE to 6 for stronger FM metallic character
• Noisy snare: Raise NOISE to ~50%, switch to WHITE noise, set Envelope B Decay to ~15% for a short, snappy, noise-heavy hit

Output Checklist

• Complex percussion patch layers LPG body, noise transient, ring mod character, and FM metallic overtones
• LPG operates in VCA+LPF mode with Envelope A providing the percussive strike
• Main path and LPG output sum at Output Control for multi-layered drum sound
• Velocity sensitivity provides dynamic accent control
• Patch documented in patches/cascadia/complex-percussion-recipe.md with full cable routing and knob settings
• Session logged in Obsidian daily note

Key Takeaways

• Complex percussion layers multiple timbral elements: LPG body, noise transient, ring mod character, and FM metallic overtones
• Cascadia's dual output paths (VCA A main + VCA B/LPF secondary) can be summed at Output Control for multi-source drum sounds
• Each layer has its own envelope characteristics -- the LPG handles the body, the main path filter envelope handles the transient character

Next Session Preview

Session 24 builds a texture patch -- noise through the filter with S&H modulation, wave folding, and self-patching for an evolving, non-pitched sound design element.