audio-production

Audio Production

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Comprehensive guide for professional audio production across music, podcasts, video, and interactive media.

Audio Fundamentals

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

---

Recording

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

---

Essential Processing

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

---

Mixing

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

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

2. EQ (Linear Phase)
   └─→ Broad adjustments only

3. Multiband Compression
   └─→ Control specific bands

4. Stereo Width
   └─→ Enhance or narrow

5. Limiting
   └─→ Final loudness, prevent clipping

6. Dither (if needed)
   └─→ 16-bit conversion only

---

Podcast Production

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

2. De-essing
   └─→ Tame harsh "s" sounds

3. Compression
   └─→ Even out volume (3:1-4:1)

4. EQ
   └─→ HPF at 80Hz, presence boost

5. 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

---

Sound Design

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.

---

DAWs (Digital Audio Workstations)

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

---

File Formats

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

---

Best Practices

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)

---

Quality Checklist

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