Audio Engineering Patterns

Technical foundations for audio production and sound design.

Signal Flow Fundamentals

The Audio Chain

Source → Processing → Summing → Output

[Mic/Synth] → [EQ/Comp/FX] → [Mix Bus] → [Master] → [Playback]

Gain Staging

Maintain optimal levels at each stage:

| Stage | Target Level | Headroom | |-------|--------------|----------| | Recording | -18 to -12 dBFS | 12-18 dB | | Processing | -18 to -12 dBFS | 12-18 dB | | Mix Bus | -6 to -3 dBFS | 3-6 dB | | Master | -1 to -0.3 dBFS | True peak limit |

Rule: If a plugin sounds bad, check your input level first.

Frequency Fundamentals

The Spectrum

| Range | Frequency | Character | Instruments | |-------|-----------|-----------|-------------| | Sub Bass | 20-60 Hz | Felt, not heard | Kick, bass, 808 | | Bass | 60-250 Hz | Foundation, warmth | Bass, low vocals | | Low Mids | 250-500 Hz | Body, mud | Guitars, vocals | | Mids | 500-2000 Hz | Presence, honk | Vocals, snare | | Upper Mids | 2-4 kHz | Clarity, harshness | Vocals, guitars | | Presence | 4-6 kHz | Definition, sibilance | Vocals, cymbals | | Brilliance | 6-10 kHz | Air, shimmer | Cymbals, strings | | Air | 10-20 kHz | Sparkle, hiss | Room, breath |

EQ Patterns

Subtractive First:

Find problem frequencies (boost, sweep, identify)
Cut problems (narrow Q)
Boost characteristics (wide Q)

Common Problem Areas: | Issue | Frequency | Action | |-------|-----------|--------| | Mud | 200-400 Hz | Cut | | Boxiness | 400-600 Hz | Cut | | Honk | 800-1000 Hz | Cut | | Harshness | 2-4 kHz | Cut or dip | | Sibilance | 5-8 kHz | De-ess or cut |

Dynamics Processing

Compression Parameters

| Parameter | Function | Typical Range | |-----------|----------|---------------| | Threshold | When compression starts | -30 to 0 dB | | Ratio | How much compression | 2:1 to 20:1 | | Attack | How fast it engages | 0.1-100 ms | | Release | How fast it lets go | 50-1000 ms | | Knee | Soft/hard transition | 0-12 dB | | Makeup | Compensate for gain reduction | As needed |

Compression Archetypes

| Style | Attack | Release | Ratio | Use | |-------|--------|---------|-------|-----| | Transparent | Fast | Auto | 2-3:1 | Vocals, mix bus | | Punchy | Slow | Medium | 4-6:1 | Drums, bass | | Glue | Medium | Slow | 2-4:1 | Mix bus, groups | | Limiting | Fast | Fast | 10:1+ | Peaks, protection | | Pumping | Slow | Fast | High | Creative effect |

Sidechain Patterns

Trigger Source → Sidechain Input → Compressor → Target

[Kick] → [SC Input] → [Comp on Bass] → [Ducked Bass]

Use for:

Kick/bass separation
Vocal ducking
Rhythmic pumping
De-essing (high-pass SC)

Spatial Processing

Reverb Types

| Type | Character | Use | |------|-----------|-----| | Room | Small, tight | Drums, guitars | | Hall | Large, long | Orchestral, pads | | Plate | Dense, bright | Vocals, snare | | Chamber | Warm, smooth | Strings, vocals | | Spring | Bouncy, lo-fi | Guitars, vintage | | Convolution | Realistic spaces | Film, realism | | Algorithmic | Controllable | Everything |

Reverb Parameters

| Parameter | Effect | |-----------|--------| | Pre-delay | Separation from source (20-80ms typical) | | Decay/RT60 | Length of tail | | Size | Room dimensions | | Damping | High-frequency absorption | | Diffusion | Density of reflections | | Mix/Wet | Blend with dry signal |

Delay Patterns

| Pattern | Timing | Use | |---------|--------|-----| | Slapback | 75-150 ms | Vocals, rockabilly | | Doubling | 20-50 ms | Width, thickness | | Rhythmic | Tempo-synced | Groove, production | | Ping-pong | L/R alternating | Width, movement | | Ambient | Long, diffused | Atmosphere |

Tempo Sync Formula:

ms = 60000 / BPM

1/4 note = 60000 / BPM
1/8 note = 30000 / BPM
1/16 note = 15000 / BPM
Dotted = value × 1.5
Triplet = value × 0.667

Mix Architecture

Bus Structure

                    ┌─────────────┐
                    │  Master Bus │
                    └──────┬──────┘
           ┌───────────────┼───────────────┐
           ▼               ▼               ▼
    ┌──────────┐    ┌──────────┐    ┌──────────┐
    │ Drum Bus │    │Music Bus │    │Vocal Bus │
    └────┬─────┘    └────┬─────┘    └────┬─────┘
         │               │               │
    ┌────┴────┐     ┌────┴────┐     ┌────┴────┐
    │K│S│H│OH│     │B│G│K│Pd│     │Ld│BV│Fx│
    └─────────┘     └─────────┘     └─────────┘

Mix in Mono First

Get balance right in mono
Check phase relationships
Add stereo width last
Always reference in mono

Static Mix Workflow

Faders only: Get rough balance
Pan: Create space left/right
EQ: Carve frequency space
Compression: Control dynamics
Reverb/Delay: Add depth
Automation: Movement and interest

Mastering Fundamentals

Chain Order

EQ → Compression → Saturation → Stereo Enhancement → Limiting

Target Levels

| Platform | Target LUFS | True Peak | |----------|-------------|-----------| | Streaming (general) | -14 LUFS | -1 dB | | Apple Music | -16 LUFS | -1 dB | | YouTube | -14 LUFS | -1 dB | | Club/DJ | -6 to -9 LUFS | -0.3 dB | | Podcast | -16 LUFS | -1 dB | | Broadcast | -24 LUFS | -2 dB |

Metering

| Meter Type | Measures | Use For | |------------|----------|---------| | Peak | Instantaneous max | Clipping prevention | | RMS | Average level | Perceived loudness | | LUFS | Perceptual loudness | Streaming compliance | | Phase | L/R correlation | Mono compatibility | | Spectrum | Frequency content | Balance verification |

DSP Fundamentals

Basic DSP Operations

| Operation | Effect | |-----------|--------| | Gain | Multiply signal amplitude | | Sum | Add signals together | | Delay | Time offset (samples) | | Filter | Frequency-dependent gain | | Convolution | Apply impulse response |

Filter Types

| Type | Effect | Use | |------|--------|-----| | Low-pass (LPF) | Removes highs | Warmth, lo-fi | | High-pass (HPF) | Removes lows | Clarity, cleanup | | Band-pass (BPF) | Isolates range | Radio, telephone | | Notch | Removes specific freq | Feedback, hum | | All-pass | Phase shift only | Phasers | | Comb | Periodic peaks/notches | Flanging |

Common Sample Rates

| Rate | Use | Nyquist | |------|-----|---------| | 44.1 kHz | CD, streaming | 22.05 kHz | | 48 kHz | Video, broadcast | 24 kHz | | 88.2 kHz | High-res (2× 44.1) | 44.1 kHz | | 96 kHz | High-res production | 48 kHz |

Sound Design Patterns

Synthesis Types

| Type | Method | Character | |------|--------|-----------| | Subtractive | Filter harmonics | Classic analog | | Additive | Sum partials | Precise, digital | | FM | Modulate frequency | Complex, metallic | | Wavetable | Morph waveforms | Evolving, digital | | Granular | Micro-samples | Textural, ambient | | Physical Modeling | Simulate physics | Realistic | | Sampling | Recorded audio | Any source |

Layering Strategy

Layer 1: Sub (20-80 Hz) - Foundation
Layer 2: Body (100-400 Hz) - Weight
Layer 3: Character (400-2000 Hz) - Identity
Layer 4: Presence (2-6 kHz) - Cut-through
Layer 5: Air (8-16 kHz) - Sparkle

Movement Techniques

LFO modulation (filter, pitch, amplitude)
Envelope shaping (attack, decay curves)
Automation (any parameter over time)
Randomization (subtle variation)
Sidechain (rhythmic pumping)

References

references/frequency-chart.md - Detailed frequency guide
references/plugin-chains.md - Common processing chains
references/daw-shortcuts.md - DAW workflow tips