Stereo Phaser Effect — User Guide

What this does

This script implements a stereo phaser effect — recreating the classic analog phaser sound with enhanced stereo imaging. The effect works by creating a series of frequency notches that sweep up and down the spectrum, caused by phase cancellation between the original signal and a phase-shifted version. Stereo enhancement is achieved by applying different phase offsets to left and right channels, creating a swirling, immersive spatial effect.

Key Features:

• 7 Built-in Presets — From classic 70s to modern sci-fi effects
• Stereo Phase Offset — Creates width and movement between channels
• LFO Modulation — Controls the sweeping motion of the effect
• Resonance Control — Adds emphasis to the notch frequencies
• Dry/Wet Mix — Blends original and processed signals
• Auto Stereo Conversion — Converts mono to stereo for width effects

Technical Implementation: (1) Stereo handling: If input is mono, automatically converts to stereo. (2) Feedback/resonance stage: Creates sharper notches by adding self-modulated delayed signal. (3) Main phaser stage: Combines dry signal with phase-shifted version using time-varying delay modulation. (4) Stereo phase offset: Left and right channels use different LFO phases (offset by stereo_Phase_Offset_deg). (5) Dry/wet mixing: Blends original and processed signals according to mix parameter. Core formula: output = (1-mix)×dry + mix×dry[delay], where delay = base_delay + modulation×sin(2π×rate×time + channel_phase_offset).

Quick start

1. In Praat, select exactly one Sound object (mono or stereo).
2. Run script… → stereo_phaser_effect.praat.
3. Choose a Preset or select "Custom" to adjust parameters manually.
4. Adjust LFO Settings to control the sweep motion:
   • Rate_hz: Speed of the sweep (0.1-10 Hz)
   • Depth_ms: Intensity of the modulation (0.5-5 ms)
   • Center_delay_ms: Base delay time (1-10 ms)
5. Set Stereo_Phase_Offset_deg (180° = maximum width, 0° = mono).
6. Adjust Feedback_Resonance (0.0-0.9) for sharper notches.
7. Set Dry_Wet_Mix (0.0-1.0) to blend effect with original.
8. Click OK — phaser applied, result named "originalname_phaser".

Phaser Theory

How Phasing Works

The Phase Cancellation Principle

Basic phaser operation:

Frequency Notch Creation

Notch frequencies occur where:

    Amplitude
       ▲
       │    ┌───┐
       │    │   │
       │   ┌┘   └┐
       │   │     │
       │  ┌┘     └┐
       │  │       │    ┌───┐
       │ ┌┘       └┐   │   │
       │ │         │  ┌┘   └┐
       └─┴─────────┴──┴─────┴───► Frequency
        Notch 1  Notch 2  Notch 3
    

Stereo Enhancement

Phase Offset Between Channels

Stereo phaser formula:

Phase Offset Values

Feedback Resonance

Sharpening the Notches

Resonance feedback stage:

Resonance Characteristics

Parameter Relationships

LFO Rate and Depth Interaction

Rate_hz (sweep speed):

Depth_ms (modulation intensity):

Center_delay_ms (base delay):

Complete Processing Pipeline

Effect Presets

Classic 70s Phaser

Slow & Deep

Jet Plane (High Resonance)

Fast Wobble

Wide Stereo Widener

Sci-Fi Raygun

Parameters

LFO Settings (The Sweep)

Stereo Image

Intensity

Output

Applications

Guitar Effects

Use case: Classic phaser tones for electric guitar

Technique: Use "Classic 70s Phaser" preset with medium mix (0.4-0.6)

Tips:

• Apply to clean or slightly overdriven guitar
• Use stereo phase offset 90-180° for wide image
• Lower resonance (0.3-0.5) for traditional sound
• Higher resonance (0.6-0.8) for modern, dramatic effects

Vocal Processing

Use case: Adding movement and space to vocals

Technique: Use subtle settings with low mix

Settings:

• Rate: 0.3-1.0 Hz (slow to medium)
• Depth: 1.0-2.0 ms (subtle to medium)
• Mix: 0.2-0.4 (mostly dry)
• Resonance: 0.2-0.4 (gentle)

Result: Adds subtle movement without obvious "effected" sound

Synth and Pad Textures

Use case: Creating evolving, animated synth sounds

Technique: Use "Slow & Deep" preset or similar

Settings:

• Very slow rates (0.1-0.3 Hz) for gradual evolution
• Medium to high depth (2.0-4.0 ms) for noticeable sweeps
• Stereo phase offset 180° for maximum width
• Medium to high mix (0.5-0.8) for prominent effect

Stereo Enhancement

Use case: Adding width to mono sources

Technique: Use "Wide Stereo Widener" preset

Key principles:

• Very subtle modulation (low depth, low rate)
• No resonance for natural sound
• Low mix (0.2-0.4) to preserve original character
• 180° phase offset for maximum stereo difference

Result: Mono sources gain stereo width without obvious phasing

Sound Design and Special Effects

Use case: Creating sci-fi, futuristic, or unusual sounds

Technique: Use extreme settings from "Jet Plane" or "Sci-Fi Raygun" presets

Creative approaches:

• High resonance (>0.7) for pronounced, resonant sweeps
• Fast rates (2-5 Hz) for rhythmic, obvious modulation
• Deep modulation (3-5 ms) for dramatic frequency sweeps
• High mix (0.7-1.0) for fully processed sound

Practical Workflow Examples

Advanced Techniques

Troubleshooting Common Issues

Technical Deep Dive

Digital Implementation

Time-Varying Delay Line

The core phaser algorithm uses a modulated delay line:

Frequency Response Analysis

The phaser creates a comb filter response:

Comparison with Other Modulation Effects

Phaser vs Flanger vs Chorus

Historical Context