Envelope Generators

Envelope generators (EGs) are fundamental components in sound synthesis systems that produce control signals to shape how sounds evolve over time. They are most commonly associated with controlling the amplitude of a sound, though they can modulate any parameter including filter cutoff, pitch, or modulation depth.

Basic Structure

The classic envelope generator follows the ADSR model, consisting of four primary stages:

1. Attack - Time taken to reach peak level from zero
2. Decay - Time taken to fall from peak to sustain level
3. Sustain - Level maintained while a key/trigger remains active
4. Release - Time taken to return to zero after key/trigger release

Types and Variations

Simple Envelopes

• AR (Attack-Release) envelopes
• AD (Attack-Decay) envelopes
• ASR (Attack-Sustain-Release) envelopes

Advanced Configurations

• Multi-stage envelopes with additional segments
• Loop envelopes that can repeat segments
• Complex envelopes with curved segments and multiple breakpoints

Applications

Envelope generators are essential in:

• Synthesizer and software synthesizers
• Digital Audio Workstation environments
• Sound Design tools
• Modular Synthesis systems

Musical Context

Envelopes help create:

• Natural instrument simulations
• Percussion Synthesis elements
• Ambient Music textures
• Sound Effect sound effects

Modern Developments

Contemporary envelope generators often feature:

• Digital control and precision
• Multiple simultaneous outputs
• MIDI integration
• CV Gate compatibility
• Visual feedback and editing
• Modulation Matrix flexibility

Technical Considerations

When implementing envelope generators, designers must consider:

• Timing accuracy
• Signal resolution
• Control Voltage levels
• Digital Control design
• Trigger Input methods

The envelope generator remains a cornerstone of sound design, providing essential dynamic control over sonic parameters in both analog and digital domains.