audio-production

The Audio Signal Chain

```

SOURCE → CAPTURE → PROCESS → OUTPUT

Detailed:

┌─────────┐ ┌─────────┐ ┌─────────┐ ┌─────────┐

│ Source │→→→│ Mic │→→→│ Preamp │→→→│Interface│

│(voice, │ │ │ │ │ │ (A/D) │

│ instr.) │ │ │ │ │ │ │

└─────────┘ └─────────┘ └─────────┘ └────┬────┘

│

▼

┌─────────┐ ┌─────────┐ ┌─────────┐ ┌─────────┐

│Speakers │←←←│ (D/A) │←←←│ Mix │←←←│ DAW │

│Headphone│ │Interface│ │ Master │ │Recording│

└─────────┘ └─────────┘ └─────────┘ └─────────┘

```

Key Audio Concepts

| Concept | Definition | Standard |

| ----------------- | ---------------------------- | ------------------------------- |

| Sample Rate | Samples per second | 44.1kHz, 48kHz, 96kHz |

| Bit Depth | Dynamic range resolution | 16-bit, 24-bit, 32-bit float |

| Bit Rate | Data per second (compressed) | 128-320 kbps (MP3) |

| Dynamic Range | Loudest to quietest | ~96dB (16-bit), ~144dB (24-bit) |

| Headroom | Space below 0 dBFS | -6 to -18 dB typical |

Frequency Spectrum

```

20 Hz 20,000 Hz

├───────────────────────────────────────────────────────┤

SUB-BASS │ BASS │ LOW-MID │ MID │ HIGH-MID │ HIGH

20-60 │ 60-250 │ 250-500 │500-2k │ 2k-6k │ 6k-20k

│ │ │ │ │

Rumble │ Warmth │ Body │ Pres- │ Presence │ Air

Feel │ Punch │ Muddiness│ ence │ Harshness│ Sibilance

```

Decibel Reference Points

```

dBFS (Full Scale):

0 dBFS ████████████ Digital maximum (clipping)

-3 dBFS ██████████ Peaks (leave headroom)

-6 dBFS █████████ Recommended peak ceiling

-12 dBFS ███████ Average loud signal

-18 dBFS ██████ Recommended recording level

-24 dBFS ████ Conservative level

-60 dBFS █ Noise floor target

```

---

Microphone Types

| Type | Principle | Best For |

| ------------- | ---------------- | ------------------------------- |

| Dynamic | Moving coil | Loud sources, live, durable |

| Condenser | Capacitor | Studio vocals, acoustic, detail |

| Ribbon | Thin metal strip | Vintage tone, smooth highs |

| USB | Built-in ADC | Podcasts, convenience |

Polar Patterns

```

CARDIOID FIGURE-8 OMNI

╭─────╮ ╭───╮ ╭─────╮

╭─┤ ├─╮ ╭─┤ ├─╮ ╭─┤ ├─╮

│ │ │ │ │ │ │ │ │ │ │ │

│ │ ● │ │ │ │ ● │ │ │ │ ● │ │

│ │ │ │ │ │ │ │ │ │ │ │

╰─┤ ├─╯ ╰─┤ ├─╯ ╰─┤ ├─╯

╰─────╯ ╰───╯ ╰─────╯

Front pickup Front + Back All around

```

Recording Levels

```

Target Peaks: -12 to -6 dBFS

Average Level: -18 to -12 dBFS

Why?

• Leaves headroom for processing
• Matches analog equipment sweet spot
• Prevents digital clipping
• 24-bit has plenty of resolution

```

Recording Best Practices

• [ ] Set gain before recording (never during)
• [ ] Record at 24-bit minimum
• [ ] Use 48kHz for video, 44.1kHz for music
• [ ] Monitor with headphones
• [ ] Record a few seconds of room tone
• [ ] Check phase when using multiple mics
• [ ] Label takes immediately

---

EQ (Equalization)

```

Types:

• High-pass filter (HPF): Removes low frequencies
• Low-pass filter (LPF): Removes high frequencies
• Bell/Peak: Boost or cut specific frequency
• Shelf: Boost or cut above/below frequency

Common Applications:

┌─────────────────────────────────────────┐

│ Vocal: │

│ HPF at 80-100Hz (remove rumble) │

│ Cut 200-300Hz (reduce mud) │

│ Boost 3-5kHz (presence) │

│ Shelf boost 10kHz+ (air) │

├─────────────────────────────────────────┤

│ Kick Drum: │

│ Boost 50-80Hz (sub) │

│ Cut 300-400Hz (boxiness) │

│ Boost 3-5kHz (attack/click) │

├─────────────────────────────────────────┤

│ Electric Guitar: │

│ HPF at 80Hz │

│ Cut 400-600Hz if muddy │

│ Boost 2-4kHz (bite) │

└─────────────────────────────────────────┘

```

Compression

```

Parameters:

┌────────────────────────────────────────────────┐

│ Threshold: Level where compression starts │

│ Ratio: Amount of compression (4:1, 8:1, etc.) │

│ Attack: Time to engage (fast=punch, slow=body)│

│ Release: Time to disengage │

│ Knee: Hard (sudden) or soft (gradual) │

│ Makeup Gain: Restore lost volume │

└────────────────────────────────────────────────┘

Common Settings:

┌─────────────────────────────────────────┐

│ Vocals: 3:1-4:1, medium attack/release │

│ Drums: 4:1-8:1, fast attack │

│ Bass: 4:1, medium attack │

│ Mix Bus: 2:1-3:1, slow attack, 1-3dB GR│

└─────────────────────────────────────────┘

```

Reverb

| Type | Character | Use |

| ----------- | --------------- | ------------------- |

| Room | Small, tight | Natural ambience |

| Hall | Large, spacious | Orchestral, ballads |

| Plate | Bright, smooth | Vocals, snare |

| Spring | Vintage, boingy | Guitar, lo-fi |

| Chamber | Warm, dense | Natural depth |

```

Key Parameters:

• Pre-delay: Time before reverb (50-100ms for vocals)
• Decay/RT60: How long it lasts
• Damping: High-frequency absorption
• Size: Room dimensions
• Mix/Wet-Dry: Balance with original

```

Delay

| Type | Application |

| -------------- | ------------------------------ |

| Slapback | 50-150ms, rockabilly, presence |

| Stereo | Different L/R times, width |

| Ping-pong | Alternating L/R, interest |

| Tempo-sync | 1/4, 1/8 notes, rhythmic |

---

Gain Staging

```

Signal Flow Levels:

┌─────────────────────────────────────────┐

│ Input: -18 dBFS (sweet spot) │

│ ↓ │

│ Plugin 1: Output matches input level │

│ ↓ │

│ Plugin 2: Output matches input level │

│ ↓ │

│ Fader: Unity (0 dB) ideally │

│ ↓ │

│ Bus: -12 to -6 dBFS peaks │

│ ↓ │

│ Master: -6 dBFS peaks (before limit) │

└─────────────────────────────────────────┘

```

Panning Guidelines

```

Stereo Field:

Hard L L L-C CENTER R-C R Hard R

│ │ │ │ │ │ │

│ │ │ │ │ │ │

Rhythm Gtr1 Keys1 Vocal Keys2 Gtr2 Rhythm

Gtr BVox1 Bass BVox2 Gtr

Kick

Snare

Common Positions:

• Center (0): Lead vocal, bass, kick, snare
• Slight L/R: Main instruments, harmonies
• Wide L/R: Rhythm guitars, stereo keys
• Hard L/R: Doubled parts, effects

```

Frequency Balancing

```

Making space (subtractive EQ approach):

┌────────────────────────────────────────────┐

│ Kick: Boost 60Hz │ Cut from Bass here │

│ Bass: Boost 80-100 │ Cut from Kick here │

│ Gtr: Owns 1-3kHz │ Cut vocal slightly │

│ Vocal: Boost 3-5kHz │ Cut guitar slightly │

└────────────────────────────────────────────┘

Each element should have its own frequency "home"

```

Mix Bus Processing

```

Typical Chain:

1. Subtle EQ (tonal shaping)
2. Light compression (2:1, 1-3dB GR)
3. Stereo enhancement (if needed)
4. Limiter (only for reference bounce)

Keep mix bus processing minimal!

Leave headroom for mastering.

```

---

Mastering Goals

1. Tonal Balance: Even frequency response
2. Dynamics: Appropriate loudness/dynamics
3. Stereo Image: Width and mono compatibility
4. Translation: Sounds good everywhere
5. Format: Prepare for distribution

Loudness Standards

| Platform | Target | Measurement |

| ------------------ | -------------- | ----------- |

| Spotify | -14 LUFS | Integrated |

| Apple Music | -16 LUFS | Integrated |

| YouTube | -14 LUFS | Integrated |

| Broadcast (US) | -24 LUFS | Integrated |

| Broadcast (EU) | -23 LUFS | Integrated |

| CD | -9 to -12 LUFS | Integrated |

Mastering Chain (Typical)

```

1. Reference Import

└─→ Compare to commercial releases

1. EQ (Linear Phase)

└─→ Broad adjustments only

1. Multiband Compression

└─→ Control specific bands

1. Stereo Width

└─→ Enhance or narrow

1. Limiting

└─→ Final loudness, prevent clipping

1. Dither (if needed)

└─→ 16-bit conversion only

```

---

Recording Setup

```

Recommended Signal Chain:

Mic → Audio Interface → DAW

Equipment Tiers:

┌─────────────────────────────────────────┐

│ Budget: USB Mic (Blue Yeti, AT2020) │

│ Mid: SM7B + Cloudlifter + Interface│

│ Pro: Large diaphragm condenser │

│ + high-end preamp │

└─────────────────────────────────────────┘

```

Podcast Processing Chain

```

1. Noise Reduction

└─→ Remove room noise, hum

1. De-essing

└─→ Tame harsh "s" sounds

1. Compression

└─→ Even out volume (3:1-4:1)

1. EQ

└─→ HPF at 80Hz, presence boost

1. Limiter

└─→ Catch peaks, -1 dBFS ceiling

Target: -16 LUFS (mono), -19 LUFS (stereo)

True Peak: -1 dBTP

```

Podcast Export Settings

```

Standard:

• Format: MP3 or AAC
• Bitrate: 128 kbps (mono), 192 kbps (stereo)
• Sample rate: 44.1 kHz

High Quality:

• Format: AAC
• Bitrate: 256 kbps
• Sample rate: 48 kHz

Chapters: Use ID3 tags for chapter markers

Artwork: 3000x3000 minimum, JPG or PNG

```

---

Creating Sounds

```

Approaches:

1. Recording: Capture real sounds (foley)
2. Synthesis: Create from oscillators
3. Sampling: Manipulate existing sounds
4. Processing: Transform through effects
5. Layering: Combine multiple sources

```

Synthesis Types

| Type | Method | Sound Character |

| --------------------- | -------------------- | --------------------- |

| Subtractive | Filter oscillators | Classic analog |

| FM | Frequency modulation | Metallic, bells |

| Wavetable | Morphing waveforms | Modern, evolving |

| Granular | Tiny sound particles | Texture, pads |

| Additive | Stack sine waves | Precise, organs |

| Physical Modeling | Simulate physics | Realistic instruments |

Layering Formula

```

Sound Design Stack:

┌─────────────────────────────────────┐

│ TOP: High frequencies (air, presence)│

│ MID: Character, tone │

│ LOW: Foundation, weight │

│ SUB: Felt, not heard (20-60Hz) │

│ TRANSIENT: Attack, punch │

└─────────────────────────────────────┘

Process each layer separately, combine at end.

```

---

| DAW | Strengths | Platform |

| ---------------- | ---------------------------- | -------- |

| Pro Tools | Industry standard, editing | All |

| Logic Pro | Complete package, Apple | macOS |

| Ableton Live | Live performance, electronic | All |

| FL Studio | Beat making, workflow | All |

| Reaper | Customizable, affordable | All |

| Cubase | MIDI, composition | All |

| Studio One | Modern workflow | All |

| Audacity | Free, simple editing | All |

---

| Format | Type | Quality | Use |

| -------- | ------------ | -------- | ------------------- |

| WAV | Uncompressed | Lossless | Production, archive |

| AIFF | Uncompressed | Lossless | Mac production |

| FLAC | Compressed | Lossless | Archive, audiophile |

| ALAC | Compressed | Lossless | Apple ecosystem |

| MP3 | Compressed | Lossy | Distribution |

| AAC | Compressed | Lossy | Streaming, Apple |

| OGG | Compressed | Lossy | Games, open source |

Export Specifications

```

For Mastering:

• Format: WAV
• Bit depth: 24-bit (or 32-bit float)
• Sample rate: Match session (typically 44.1/48kHz)
• Headroom: -6 dBFS peaks

For Distribution:

• Format: WAV or FLAC (lossless)
• Bit depth: 16-bit (with dither)
• Sample rate: 44.1 kHz
• Loudness: Platform target LUFS

```

---

DO:

• Record at proper levels (-18 dBFS average)
• Use reference tracks
• Take breaks (ear fatigue is real)
• Check mono compatibility
• Use subtractive EQ first
• Process in series, not parallel (usually)
• Save project versions regularly
• Export stems for backup

DON'T:

• Record with processing (usually)
• Mix at high volumes
• Over-compress everything
• Solo instruments too long
• Trust only one playback system
• Rush the mixing process
• Forget to dither (16-bit only)
• Master your own mixes (ideally)

---

Pre-Export

• [ ] Gain staging correct throughout
• [ ] No clipping or distortion
• [ ] Phase issues resolved
• [ ] Mono compatibility checked
• [ ] Low-end translation verified
• [ ] High frequencies not harsh

Final Check

• [ ] Listen on multiple systems
• [ ] Check in car, phone, earbuds
• [ ] Verify format specifications
• [ ] Confirm LUFS target met
• [ ] True peak below -1 dBTP
• [ ] Metadata correctly embedded