🔊Sound Design Unit 14 – Advanced Mixing: Compression & Effects

Key Concepts

• Compression reduces dynamic range by attenuating signals above a set threshold level
• Compression ratio determines how much gain reduction is applied when the signal exceeds the threshold (2:1, 4:1, 10:1)
• Attack time controls how quickly the compressor reacts to the input signal exceeding the threshold (fast attack for transients, slow attack for smooth leveling)
• Release time sets how quickly the compressor returns to unity gain after the signal falls below the threshold (fast release for punchy sound, slow release for natural decay)
  • Release times that are too short can cause pumping or breathing artifacts
• Knee determines the transition between uncompressed and compressed states (hard knee for precise control, soft knee for more musical compression)
• Makeup gain compensates for the overall reduction in volume caused by compression
• Sidechain allows an external signal to control the compression instead of the input signal itself (ducking, pumping effects)

Types of Compression

• Downward compression reduces the level of signals that exceed the threshold
• Upward compression increases the level of signals below the threshold to reduce dynamic range
• Parallel compression blends compressed and uncompressed signals for added punch and clarity
  • Typically uses high compression ratios and low thresholds for aggressive compression
• Multiband compression splits the signal into frequency bands and compresses each band independently
  • Allows for more precise control over specific frequency ranges (low-end, midrange, high-end)
• Sidechain compression uses an external signal to control the compression of the input signal
• Limiting is a form of compression with high ratios (10:1 or higher) to prevent clipping and maintain peak levels
• Dynamic EQ applies compression or expansion to specific frequency ranges based on the input signal's energy in those ranges

Essential Effects

• Equalization (EQ) shapes the frequency balance of a signal by boosting or cutting specific frequency ranges
  • High-pass and low-pass filters remove frequencies below or above a set cutoff point
  • Shelving filters boost or cut frequencies above or below a set frequency
  • Parametric EQ offers control over frequency, gain, and bandwidth (Q) for precise adjustments
• Reverb simulates the natural reflections and decay of sound in a space
  • Room, hall, chamber, and plate reverbs emulate different acoustic environments
  • Pre-delay, decay time, and diffusion control the character of the reverb
• Delay repeats the input signal at timed intervals
  • Simple delay, ping-pong delay, and multi-tap delay create different rhythmic and spatial effects
  • Feedback and mix controls determine the number of repeats and the balance between dry and wet signals
• Modulation effects add movement and depth to sounds
  • Chorus creates a thickening effect by combining slightly detuned and delayed copies of the signal
  • Flanger produces a sweeping, jet-like sound by mixing the signal with a delayed copy and modulating the delay time
  • Phaser creates a series of peaks and notches in the frequency spectrum, resulting in a swooshing effect

Signal Chain Basics

• The order of effects in a signal chain can significantly impact the final sound
• Dynamics processing (compression, limiting) is typically applied early in the chain to control peaks and shape the overall envelope
• EQ is often used after dynamics to refine the frequency balance and remove any unwanted artifacts
• Time-based effects (reverb, delay) are usually placed later in the chain to avoid smearing the sound and maintain clarity
  • Modulation effects can be placed before or after time-based effects, depending on the desired result
• Stereo imaging tools (wideners, panning) are often applied last to enhance the spatial characteristics of the sound
• Gain staging ensures that each effect in the chain receives an optimal input level to prevent clipping and maintain signal-to-noise ratio
• Bypass individual effects or entire signal chains to compare the processed and unprocessed sounds and make informed decisions

Advanced Techniques

• Serial compression involves using multiple compressors in series, each with different settings, to achieve more complex and musical dynamics control
  • Gentle compression followed by more aggressive compression can maintain punch while controlling peaks
• Parallel processing allows blending of processed and unprocessed signals to maintain dynamics while enhancing specific characteristics
  • Parallel distortion adds harmonic content and grit without overwhelming the original signal
  • Parallel EQ can emphasize or attenuate specific frequencies without affecting the overall balance
• Mid/side processing separates the signal into mid (center) and side (stereo) components for independent processing
  • Widening the side channel can create a more expansive stereo image
  • Compressing the mid channel can maintain vocal clarity in a dense mix
• Dynamic EQ and multiband compression allow for frequency-dependent processing, which can solve specific mix challenges
  • Reducing sibilance in a vocal track using dynamic EQ in the high-frequency range
  • Controlling bass resonances with multiband compression in the low-end
• Automation of effect parameters can create dynamic and engaging mixes
  • Gradually increasing reverb decay time during a breakdown section
  • Automating EQ to emphasize specific instruments during a solo or lead passage

Common Pitfalls

• Over-compression can lead to a lifeless, squashed sound lacking dynamics and punch
• Excessive use of reverb can make a mix sound muddy and lack definition
• Applying effects without a clear purpose can clutter the mix and detract from the overall impact
• Neglecting gain staging can introduce unwanted distortion or noise in the signal chain
  • Improper gain structure can also lead to inconsistent effect behavior and reduced headroom
• Relying too heavily on presets without understanding the underlying parameters can result in generic or ill-suited processing
• Failing to use reference tracks can lead to mixes that lack industry-standard balance, clarity, and punch
• Ignoring the importance of mono compatibility can cause phase issues and unintended cancellations when the mix is played back in mono
• Applying processing to individual tracks without considering the context of the entire mix can lead to frequency masking and imbalances

Practical Applications

• Vocal compression can even out dynamic variations, increase sustain, and add presence to a performance
  • Gentle compression (2:1 to 4:1 ratio) with medium attack and release times for a natural sound
  • Faster attack and release times can emphasize consonants and transients for an upfront vocal style
• Drum bus compression can glue the various drum elements together and add punch and cohesion to the rhythm section
  • Medium to high ratios (4:1 to 10:1) with medium attack and release times for a tight, controlled sound
  • Parallel compression can maintain transient impact while adding density and weight to the drums
• Bass compression can control peak levels, add sustain, and enhance the low-end presence in a mix
  • Slower attack times (50ms or higher) to preserve the initial transient and maintain the bass' attack
  • Faster release times (100ms or lower) to avoid pumping and maintain a consistent low-end foundation
• Master bus compression can add final glue and cohesion to a mix, controlling overall dynamics and enhancing loudness
  • Low ratios (1.5:1 to 2:1) with medium to slow attack and release times for a transparent, musical result
  • Multiband compression can address frequency-specific issues and achieve a more balanced final master

Tools and Plugins

• Stock DAW compressors (Pro Tools Dynamics III, Logic Pro Compressor, Ableton Live Compressor) offer essential features and reliable performance
• Third-party compressor plugins emulate classic hardware units or provide unique processing algorithms
  • Waves CLA-2A and CLA-3A: modeled after the iconic LA-2A and LA-3A optical compressors
  • UAD 1176 and Teletronix LA-2A: hardware-modeled plugins that capture the character of vintage FET and optical compressors
  • FabFilter Pro-C 2: a versatile, modern compressor with clean, transparent processing and advanced sidechain options
• Stock DAW EQs (Pro Tools EQ III, Logic Pro Channel EQ, Ableton Live EQ Eight) provide essential tone-shaping capabilities
• Third-party EQ plugins offer additional features, analog modeling, and specialized processing
  • Waves API 550A and 550B: modeled after the classic API console EQs, known for their musical and punchy sound
  • UAD Pultec EQP-1A and MEQ-5: emulations of the revered passive tube equalizers, offering smooth and musical frequency shaping
  • FabFilter Pro-Q 3: a precise, transparent, and feature-rich EQ with dynamic mode and spectrum analyzer
• Reverb and delay plugins range from simple, algorithmic designs to complex, convolution-based models
  • Valhalla Room and VintageVerb: affordable, high-quality algorithmic reverbs with intuitive interfaces
  • Waves H-Reverb and Abbey Road Plates: realistic emulations of hardware digital reverbs and plate reverbs
  • SoundToys EchoBoy and Crystallizer: creative delay plugins with modulation, saturation, and pitch-shifting capabilities
• Modulation and creative effect plugins expand the sound design possibilities and add unique textures to mixes
  • Waves MetaFlanger and PS22 Stereo Maker: versatile flanger and phaser plugins with extensive modulation options
  • SoundToys Decapitator and Radiator: saturation and distortion plugins for adding analog warmth and grit
  • iZotope Trash 2 and FabFilter Saturn: multi-band distortion and saturation plugins for complex, frequency-dependent processing