Introduction to Analog Synthesis
Analog synthesizers create sound by generating and manipulating electrical voltages that directly represent audio waveforms. Unlike digital synthesizers that use mathematical algorithms, analog synths produce sound through real electronic circuits, giving them their characteristic warmth, imperfections, and organic qualities that many musicians prize.
Core Components and Signal Flow
Basic Signal Path
Oscillator → Filter → Amplifier → Output
↑ ↑ ↑
└───────────┴─────────┘
ModulationEssential Modules
| Module | Function | Parameters | Patch Points |
|---|---|---|---|
| VCO (Voltage Controlled Oscillator) | Generates raw waveforms | Frequency, waveform type, pulse width | Output, FM input, PWM input, sync |
| VCF (Voltage Controlled Filter) | Shapes harmonic content | Cutoff frequency, resonance, filter type | Input, output, CV input, audio FM |
| VCA (Voltage Controlled Amplifier) | Controls amplitude | Gain | Input, output, CV input |
| Envelope Generator | Creates time-based contours | Attack, decay, sustain, release | Trigger input, gate input, output |
| LFO (Low Frequency Oscillator) | Provides cyclic modulation | Rate, waveform | Output |
| Mixer | Combines signals | Level per channel | Inputs, output |
| Multiple | Duplicates signals | None | Input, outputs |
| Attenuator/Attenuverter | Controls signal level/polarity | Amount | Input, output |
Essential Patch Types
Essential Synthesizer Patch Types
Document
### Basic Patches #### 1. Classic Subtractive Synthesis – VCO → VCF → VCA → Output – EG → VCF Cutoff – EG → VCA Control – LFO → VCO Pitch (subtle amount) #### 2. Layered Oscillator Patch – VCO 1 → Mixer Channel 1 – VCO 2 (tuned to fifth or octave)
Modulation Techniques and Routing
Common Modulation Destinations
| Source | Destination | Effect |
|---|---|---|
| LFO → VCO Pitch | Vibrato | Cyclical pitch variation |
| LFO → VCF Cutoff | Filter sweeps | Wah-like timbral changes |
| LFO → VCA | Tremolo | Cyclical volume changes |
| LFO → PWM | Pulse width modulation | Dynamic harmonic movement |
| EG → VCF Cutoff | Filter envelope | Dynamic timbral evolution |
| EG → VCO Pitch | Pitch envelope | Pitch sweeps, percussion effects |
| EG → VCA | Amplitude envelope | Controls volume over time |
| Keyboard CV → VCO | Equal temperament | Notes match keyboard pitch |
| Keyboard CV → VCF | Keyboard tracking | Filter opens with higher notes |
Advanced Modulation Strategies
- Cascading modulation: LFO → EG amount → VCF cutoff
- Cross-modulation: Audio-rate modulation between two oscillators
- Self-patching: Using a module’s output to modulate one of its own parameters
- Trigger delays: Sequentially triggering multiple envelopes for complex sounds
- Clock division: Deriving related but different timing rates from a master clock
Waveform Characteristics and Uses
| Waveform | Harmonic Content | Tonal Quality | Best Uses |
|---|---|---|---|
| Sine | Fundamental only | Pure, soft | Bass, sub-bass, gentle FM |
| Triangle | Odd harmonics (decreasing) | Soft, hollow | Mellow leads, flutes, whistles |
| Sawtooth | All harmonics | Bright, buzzy | Brass, strings, rich leads |
| Square | Odd harmonics | Hollow, wooden | Woodwinds, organs, retro leads |
| Pulse | Variable (narrows with pulse width) | Nasal, thin | Clavinets, synth vocals, reeds |
| Noise (white) | All frequencies equally | Hissy | Percussion, wind, effects |
| Noise (pink) | Higher frequencies attenuated | Warmer than white | Percussive attacks, textures |
Filter Types and Characteristics
| Filter Type | Effect on Sound | Typical Uses |
|---|---|---|
| Low-pass | Removes high frequencies | Warm pads, bass, most classic synth sounds |
| High-pass | Removes low frequencies | Thin leads, percussion, clarity in dense mixes |
| Band-pass | Keeps middle, removes highs and lows | Nasal vocals, telephone effect, special FX |
| Notch/Band-reject | Removes middle, keeps highs and lows | Phaser-like effects, special FX |
| Comb | Creates regularly spaced notches | Flanging, special FX, physical modeling |
| Formant | Shapes for vocal-like sounds | Voice synthesis, talk box effects |
Resonance/Q Effects
- Low Q: Gentle roll-off, natural sound
- Medium Q: Enhances frequencies near cutoff, adds character
- High Q: Peaking at cutoff, can self-oscillate, “juicy” sound
Envelope Shaping Techniques
ADSR Parameter Settings for Common Sounds
| Sound Type | Attack | Decay | Sustain | Release | Notes |
|---|---|---|---|---|---|
| Plucked string | Very short | Medium | Zero | Short | Sharp attack, natural decay |
| Bowed string | Medium | Long | Medium-high | Medium | Gradual onset, sustained body |
| Piano | Short | Medium | Low | Long, varies | Quick attack, natural decay |
| Brass | Medium | Short | High | Medium-short | Building attack, sustain with breath |
| Pad/Strings | Long | Medium | Medium-high | Very long | Gentle fade-in, lingering release |
| Bass | Short-medium | Medium | Medium | Medium-short | Controlled attack, focused body |
| Percussion | Very short | Variable | Zero | Variable | Sharp attack, no sustain |
Other Envelope Types
- AD (Attack-Decay): Simple on/off for percussion, triggers
- ASR (Attack-Sustain-Release): Simplified envelope for sustained sounds
- DADSR (Delay-Attack-Decay-Sustain-Release): Adds initial delay before attack
- Looping envelopes: Cycle through stages for rhythmic effects
- Multi-stage envelopes: Complex shapes beyond standard ADSR
Patch Bay Routing and Signal Management
Signal Levels and Types
| Signal Type | Typical Voltage | Use | Notes |
|---|---|---|---|
| Audio | ±5V peak-to-peak | Sound signals | Can double as modulation |
| CV (Control Voltage) | 0 to +5V or ±5V | Parameter control | 1V/oct standard for pitch |
| Gate | 0V/+5V (binary) | Trigger events | Usually 0V=off, +5V=on |
| Clock | 0V/+5V pulses | Timing coordination | Varying width/frequency |
Multiple and Mixer Usage
- Use multiples to send one signal to several destinations
- Use mixers to combine signals before a destination
- Attenuate signals before mixing for better control
- Invert signals when needed for “opposite” effects
Sound Design Recipes
Bass Sounds
Fat Analog Bass
- Sawtooth or square wave
- Low-pass filter with moderate resonance
- Short attack, medium decay, medium sustain, short release
- Slight envelope amount to filter
- Slight detuning if using multiple oscillators
Sub Bass
- Sine or triangle wave
- Minimal filtering
- Short attack, long decay, medium-high sustain, medium release
- Optional: slight distortion for harmonic content on smaller speakers
Lead Sounds
Screaming Lead
- Sawtooth wave
- High-pass filter with high resonance
- Short attack, long decay, medium sustain, medium release
- LFO to pitch for vibrato
- Envelope to filter cutoff (positive amount)
Soft Lead
- Triangle or pulse wave
- Low-pass filter with low resonance
- Medium attack, medium decay, medium sustain, medium release
- Subtle LFO to pitch
- Moderate reverb or delay (external)
Pad and Ambient Sounds
Sweeping Pad
- Multiple detuned sawtooth waves
- Low-pass filter with medium resonance
- Long attack, long decay, medium sustain, long release
- Slow LFO to filter cutoff
- Optional: slow LFO to pan position (external)
Atmospheric Texture
- Noise mixed with high triangle waves
- Band-pass filter with high resonance
- Very long attack, long decay, medium sustain, very long release
- Multiple slow LFOs to various parameters
- Heavy reverb (external)
Troubleshooting Common Issues
| Problem | Possible Causes | Solutions |
|---|---|---|
| No sound | Patch cable not connected, VCA closed | Check cable connections, ensure envelope is triggered |
| Constant sound without keys pressed | VCA not properly controlled by envelope | Connect envelope to VCA control input |
| Pitch drift | Temperature changes, unstable oscillators | Allow warm-up time, recalibrate, use more stable modules |
| Unwanted noise | Ground loops, poor cable connections | Check power, use shorter cables, avoid parallel audio/CV cables |
| Distorted sound | Signal levels too high, clipping | Reduce levels, check patch points for proper voltage range |
| Clicks and pops | Fast envelope changes, DC offset | Adjust envelope times, use slew limiter, check for offset |
Patch Management Best Practices
- Document your patches: Sketch or photograph patch bay connections
- Start simple: Begin with basic patches and add complexity gradually
- Save variations: Make incremental changes to working patches
- Color-coding: Use different colored cables for audio, CV, gates/triggers
- Template patches: Develop reusable patch frameworks for different sound categories
- Learn your synth: Understand normalled connections and defaults
- Leave space: Don’t overcrowd patch bays; allow room for changes
- Test in context: Evaluate sounds in musical context, not just in isolation
Resources for Further Learning
- Books:
- “Patch & Tweak” by Kim Bjørn and Chris Meyer
- “Make: Analog Synthesizers” by Ray Wilson
- “Secrets of Analog and Digital Synthesis” by Steve DeFuria
- Online:
- Learning Synths by Ableton (interactive tutorial)
- Moog Foundation’s Dr. Bob’s Interactive Synthesizer
- VCV Rack (free virtual modular synth)
- Syntorial (ear training for synthesis)
- Communities:
- ModWiggler Forum
- r/synthesizers on Reddit
- Elektronauts
- Muff Wiggler
This cheatsheet provides a comprehensive reference for patching analog synthesizers. While digital and software synthesizers have become widespread, the principles of analog synthesis remain fundamental to sound design across all platforms.