Session 30: Drums and Percussion -- Kick, Snare, and Hats

Objective: Build kick, snare, and hi-hat patches using short envelopes, noise, and FM percussion techniques, then combine them into a complete drum beat sequence using all 4 sequencer tracks.

Warm-Up (2 min)

Load your modulated texture from Session 29. Hold a note for 10 seconds and listen to it evolve. Pads use slow envelopes and gentle modulation. Drums are the opposite extreme: the fastest envelopes possible, sounds that exist for milliseconds. Load the basic patch.

Setup

Each recipe starts from the basic patch. The drum beat in Exercise 4 combines all three sounds into one patch -- save that final combination.

Exercises

Recipe 1: Analog Kick Drum (5 min)

Using self-oscillating filter for a deep, thumpy kick (Anu Kirk p.95-96). The Evolver's analog filter in 4-pole mode produces a sine wave when resonance is high enough -- combined with a pitch envelope, this is a classic analog kick.

1. From the basic patch:
   • Osc 1 Level = 0, Osc 2 Level = 0, Osc 3 Level = 0, Osc 4 Level = 0
   • Noise Volume = 0
   • All sound comes from the self-oscillating filter
2. Self-oscillating filter for the kick body:
   • LPF Frequency = 40, Resonance = 90, 4-Pole ON
   • Env Amount = 99 (maximum positive -- the envelope sweeps the filter from high to low)
   • ENV 1: Attack = 0, Decay = 25, Sustain = 0, Release = 5
   • The filter starts high (click/punch) and decays down to the base frequency (the thump)
3. VCA -- very short:
   • ENV 2: Attack = 0, Decay = 20, Sustain = 0, Release = 5

4. Play a key. You should hear a deep thump with a punchy attack. Adjust:
   • LPF Frequency lower (30-35) for deeper kick
   • ENV 1 Decay shorter (15-20) for tighter kick, longer (30-35) for boomy kick
   • Env Amount lower (70-80) for less click on the attack
5. Add Distortion = 10 for subtle weight

Note the sound -- you will recreate this within a combined drum patch later.

Recipe 2: FM Snare (6 min)

Noise body with FM transient for a sharp, metallic snare attack (Anu Kirk p.96-97).

1. Load the basic patch fresh:
   • Osc 1 Level = 0, Osc 2 Level = 0
   • Osc 3 Shape = 1 (sine), Level = 35, Frequency = C2
   • Osc 4 Shape = 1 (sine), Level = 0, Frequency = E3 (non-harmonic interval for metallic character)
   • FM 4->3 = 60 (high FM for inharmonic "snap")
   • Noise Volume = 55 (noise provides the snare body)
2. Filter -- shapes the noise character:
   • LPF Frequency = 75, Resonance = 10, 4-Pole ON
   • Env Amount = 40
   • ENV 1: Attack = 0, Decay = 30, Sustain = 0, Release = 10
3. VCA -- short but slightly longer than the kick:
   • ENV 2: Attack = 0, Decay = 25, Sustain = 0, Release = 10
4. FM decay for the transient snap:
   • ENV 3: Destination = FM4 (FM 4->3 Amount), Amount = 70, Attack = 0, Decay = 15, Sustain = 0, Release = 5
   • The FM is strongest at the very start (the "crack") and decays quickly, leaving the noise tail

5. Play a key. You should hear a sharp transient followed by a noisy tail. Adjust:
   • Noise Volume higher for more body, lower for more crack
   • Osc 4 Frequency to different intervals for different metallic characters
   • ENV 2 Decay for snare length (20 = tight, 35 = loose)

Recipe 3: Hi-Hats (5 min)

Short noise bursts shaped by the highpass filter for bright, metallic percussion.

1. Load the basic patch fresh:
   • Osc 1 Level = 0, Osc 2 Level = 0
   • Osc 3 Shape = 1 (sine), Level = 0
   • Osc 4 Shape = 1 (sine), Level = 0
   • Noise Volume = 70 (noise is the primary source)
2. Filter -- highpass removes low end, lowpass shapes the brightness:
   • LPF Frequency = 95, Resonance = 5
   • HPF Frequency = 60 (removes all low-end content, leaving only bright noise)
   • Env Amount = 15, ENV 1: Attack = 0, Decay = 12, Sustain = 0, Release = 5
3. VCA -- extremely short for closed hat:
   • ENV 2: Attack = 0, Decay = 8, Sustain = 0, Release = 3

4. Play a key. You should hear a short, bright "tick" -- a closed hi-hat
5. For an open hi-hat variation: increase ENV 2 Decay to 35 and Release to 20. The longer decay lets the noise sustain, creating the open hat "tssssh"
6. Add Osc 3 Level = 15, FM 4->3 = 45 for metallic ring on top of the noise

Exercise 4: Combined Drum Beat Sequence (7 min)

Now combine all three drum sounds into a single sequenced patch. The sequencer modulates parameters to switch between kick, snare, and hat characters on different steps.

1. Load the basic patch fresh. Set up a versatile starting point:
   • Osc 3 Shape = 1, Level = 30, Frequency = C2
   • Osc 4 Shape = 1, Level = 0, Frequency = E3
   • FM 4->3 = 20
   • Noise Volume = 40
   • LPF Frequency = 60, Resonance = 50, 4-Pole ON
   • HPF Frequency = 20
   • Env Amount = 70, ENV 1: Attack = 0, Decay = 20, Sustain = 0, Release = 5
   • ENV 2: Attack = 0, Decay = 18, Sustain = 0, Release = 5
2. Sequencer Track 1 -- filter cutoff creates different drum characters per step:
   • Seq 1 Dest = FiL, Clock Divide = 16th, BPM = 120
   • Step 1 = 30 (low = kick), Step 2 = oFF, Step 3 = 90 (high = hat), Step 4 = 90
   • Step 5 = 65 (mid = snare), Step 6 = oFF, Step 7 = 90, Step 8 = oFF
   • Step 9 = 30, Step 10 = 90, Step 11 = 90, Step 12 = 65
   • Step 13 = 30, Step 14 = oFF, Step 15 = 90, Step 16 = 65
   • Step 17 = rST
3. Sequencer Track 2 -- resonance variation (high for kick, low for hats):
   • Seq 2 Dest = RES
   • Step 1 = 90, Step 2 = oFF, Step 3 = 5, Step 4 = 5
   • Step 5 = 20, Step 6 = oFF, Step 7 = 5, Step 8 = oFF
   • Step 9 = 90, Step 10 = 5, Step 11 = 5, Step 12 = 20
   • Step 13 = 90, Step 14 = oFF, Step 15 = 5, Step 16 = 20
   • Step 17 = rST
4. Sequencer Track 3 -- noise volume (up for snare/hat, down for kick):
   • Seq 3 Dest = NoV (Noise Volume)
   • Step 1 = 10, Step 2 = oFF, Step 3 = 70, Step 4 = 60
   • Step 5 = 80, Step 6 = oFF, Step 7 = 60, Step 8 = oFF
   • Step 9 = 10, Step 10 = 60, Step 11 = 60, Step 12 = 80
   • Step 13 = 10, Step 14 = oFF, Step 15 = 60, Step 16 = 80
   • Step 17 = rST

5. Set Trigger Select = Seq Only and press START/STOP
6. You should hear a recognizable drum pattern: kicks on beats 1, 9, 13 (low filter, high resonance, low noise), snares on 5, 12, 16 (mid filter, some noise), and hats filling in between
7. Add Distortion = 12 for weight and Delay 1 Time = 3 Steps, Level = 15 for space

Save as "Drum Machine".

Exploration (optional, hyperfocus days)

• Use Seq 4 to modulate FM amount -- creates metallic accents on specific drum hits
• Change BPM to 80 and Clock Divide to 8th for a half-time feel
• Layer the drum patch with your acid bass from Session 27 by alternating programs -- one for drums, one for bass, switching between them with MIDI program change

Output Checklist

• Kick drum sound created -- deep, punchy, self-oscillating filter
• Snare sound created -- noise + FM transient, sharp attack
• Hi-hat sound created -- filtered noise, short decay
• Complete drum beat sequence saved with 3 tracks modulating different parameters
• Session logged in Obsidian daily note

Key Takeaways

• Drum synthesis on the Evolver uses extremely short envelopes (decay under 30) -- drums are all about the first few milliseconds of a sound
• Self-oscillating filter (4-pole, resonance 85+) produces a sine wave that, combined with a fast envelope, creates classic analog kicks
• The sequencer can morph a single patch into multiple drum sounds by modulating filter, resonance, and noise on each step -- the Evolver becomes a one-voice drum machine

Next Session Preview

Session 31 sets up the Evolver for expressive live performance -- mapping mod wheel, aftertouch, and expression pedal to useful destinations. You will create a patch that responds dynamically to your playing style.