Full-Wave Rectifier (ABS) — User Guide

What this does

This script applies full-wave rectification (absolute value function) to audio: output = |input|. All negative samples become positive, effectively "flipping" the bottom half of the waveform upward. Result: Doubled frequency content (octave up), added harmonics, increased brightness, and distortion. Particularly effective on drums and percussion for adding punch and harmonics.

Quick start

1. Select one Sound object in Praat.
2. Run script… → Load Full-Wave Rectifier script.
3. Choose Preset: Default (0.99, play) / Soft Normalize / Hard Normalize / Custom.
4. If Custom: Set scale_peak and play_after_processing.
5. Click OK — processing instant, result appears as "originalname_rectified".

How It Works

Absolute Value Function

Mathematical operation:

• output = abs(input) = |input|
• If input ≥ 0: output = input (unchanged)
• If input < 0: output = -input (flipped to positive)

Example values:

• 0.5 → 0.5 (stays positive)
• -0.5 → 0.5 (flipped to positive)
• 0.8 → 0.8 (unchanged)
• -0.3 → 0.3 (flipped)

Spectral Effects

Frequency doubling:

• Rectification creates frequency doubling effect
• 100 Hz sine wave → 200 Hz after rectification
• Waveform cycles twice as fast (negative half flipped up)
• Perceived pitch rises by one octave

Harmonic generation:

• Adds odd harmonics (3rd, 5th, 7th...)
• Creates harmonic distortion
• Increases brightness (high-frequency content)
• Thicker, more aggressive sound

Presets

Parameters

Applications

Drum processing (PRIMARY USE):

• Kick drums: Add punch, weight, and harmonic content
• Snares: Increase crispness and attack definition
• Toms: Enhance presence and body
• Hi-hats/cymbals: Add brightness (use carefully, can be harsh)
• Percussion loops: Create aggressive, distorted versions

Sound design:

• Create distorted, aggressive textures
• Generate harmonic content from simple sources
• Experimental transformation of any material
• Octave-up effect on bass sounds

Electronic music:

• 808 kick processing (add harmonics)
• Synth drum enhancement
• Creating "hard" versions of soft samples
• Distortion/saturation effects

Usage Examples

Example 1: Punchy kick drum

• Source: Soft, round 808 kick
• Process: Rectification with default settings
• Result: Brighter, more aggressive kick with added harmonics
• Use: Mix with original for layered effect

Example 2: Crisp snare

• Source: Dull, muffled snare recording
• Process: Rectification → emphasizes transients
• Result: Crisper attack, enhanced presence
• Tip: Blend with original to maintain naturalness

Example 3: Aggressive percussion loop

• Source: Soft shaker/tambourine loop
• Process: Rectification with soft normalize (0.8)
• Result: Distorted, aggressive texture
• Use: Experimental electronic music, glitch aesthetics

Comparison: Original vs Rectified

Frequency content:

• Original: Fundamental + natural harmonics
• Rectified: Doubled fundamental (octave up) + added odd harmonics

Waveform shape:

• Original: Bipolar (positive and negative excursions)
• Rectified: Unipolar (all positive values)

Perceived loudness:

• Original: Natural dynamics
• Rectified: Perceived louder (more energy, brighter)

Timbre:

• Original: Natural tone
• Rectified: Brighter, harsher, more aggressive

Output

New Sound object: "originalname_rectified"

• Processing: Full-wave rectification applied (absolute value)
• Normalized: Scaled to scale_peak value
• Original: Preserved unchanged

Pro Tips

Blending technique:

• Don't use rectified version alone (often too harsh)
• Mix rectified (30-50%) with original (50-70%)
• Adds punch and harmonics while maintaining naturalness
• Use EQ on rectified layer to shape harmonics

Frequency-selective rectification:

• Filter source before rectification (e.g., HPF >100Hz)
• Rectify filtered version
• Mix with original full-range
• Result: Controlled harmonic addition

Serial processing:

• Rectify → EQ → Compress for maximum impact
• Rectification first adds harmonics
• EQ shapes the added content
• Compression tames the enhanced transients

Limitations & Warnings

When NOT to use: Vocals, melodic instruments (piano, guitar chords, strings), sustained harmonic content, classical music, broadcast/mastering (DC offset issues).