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 guidereferences/plugin-chains.md- Common processing chainsreferences/daw-shortcuts.md- DAW workflow tips