PD Voice Changer

Real-Time Voice Processing System

A professional real-time voice changer built on ESP32-S3, featuring 28 character presets, 12+ audio effects, and authentic Stormtrooper-style click sounds. Transform your voice instantly for cosplay, voice acting, and creative audio applications.

Perfect for:

• Stormtrooper cosplay with authentic helmet comlink effects
• Darth Vader costumes with deep, processed voice
• Droid characters (C-3PO, K-2SO, IG-88) with metallic voice effects
• Sci-fi helmets requiring voice processing
• Masked characters (Kylo Ren, Mandalorian, Boba Fett)
• Voice acting and creative audio projects

Feature Highlights

What is the PD Voice Changer?

The PD Voice Changer is a standalone real-time audio processor that transforms your voice through a chain of professional audio effects. Speak into the microphone, and your processed voice comes out of the speaker – instantly.

Unlike pre-recorded sound effects, voice changing happens live. Every word you say is transformed in real-time with less than 20 milliseconds of delay. You can have natural conversations while sounding like Darth Vader or a Stormtrooper.

How It Works

Your Voice → Microphone → ESP32-S3 Processing → Amplifier → Speaker
                              ↓
                    [12 Effect Stages]
                    Noise Gate → AGC → EQ → Filters →
                    Ring Mod → Tremolo → Delay → Reverb →
                    Bitcrusher → Output

The dual-core ESP32-S3 dedicates one core entirely to audio input/output, while the second core handles all effect processing. This architecture ensures smooth, glitch-free audio even with multiple effects active.

Audio Effects

Input Processing

• Noise Gate: Removes background noise when you’re not speaking. Adjustable threshold with automatic calibration mode.
• Auto-Gain Control (AGC): Maintains consistent volume regardless of mic distance.

Tone Shaping

• 3-Band Parametric EQ: Precise control over low, mid, and high frequencies.
• 4-Stage Biquad Filter Bank: High-pass, low-pass, band-pass, notch, peak, and shelf filters.

Character Effects

• Ring Modulator: Adds metallic, robotic undertones. Essential for droid voices.
• Bitcrusher: Lo-fi digital distortion for comlink/radio effects.
• Static Noise: White noise generator for radio interference effects.

Spatial Effects

• Delay/Echo: Helmet resonance simulation (10-500ms with feedback).
• Reverb: Room ambience from small helmet space to large halls.

Modulation

• Tremolo: Rhythmic volume pulsing.
• Vibrato: Pitch wobble for droid-like effects.

Character Presets

28 ready-to-use presets covering iconic characters:

Star Wars Characters

Additional Presets

• General Grievous, Emperor Palpatine, Jabba, Ewok, Watto
• Generic Robot, Alien, Deep Voice, Radio Operator
• 3 optimized “NEW” variants (Vader NEW, Trooper NEW, C-3PO NEW)
• 5 user slots for custom presets

Click Sound System

Authentic Stormtrooper helmet comlink experience:

• Automatic Playback: Click sounds play after speech ends (configurable delay)
• Random or Sequential: Pick random clicks or play in order
• WAV File Support: Use your own click sounds (44.1kHz, 16-bit)
• Per-Preset Control: Enable/disable clicks for specific presets
• Global Toggle: Double-click Mode button to enable/disable all clicks

The click sounds are stored on an SD card, so you can easily customize them with your own recordings.

Hardware

Core Components

Audio Specifications

Alternative Components

Microphone Options:

• INMP441 I2S (recommended) – Best quality, digital
• MAX9814 + ADC – Allows 3.5mm jack for swappable mics

Output Options:

• MAX98357A I2S (recommended) – DAC + Amp in one, direct speaker connection
• PCM5102A DAC – Better audio quality, requires external amplifier

Control Interface

Hardware Buttons

LED Status Indicators

Serial CLI

50+ commands for real-time control:

# Load presets
preset 0              # Load Vader preset
preset 2              # Load Stormtrooper preset

# Adjust effects
eq low 80 -6 0.7      # Cut bass at 80Hz
ringmod 45 0.3        # Set ring modulator
reverb 40             # Set reverb level

# Calibration
cal start             # Start noise calibration
cal stop              # Apply calibration

# Click sounds
click on              # Enable click sounds
click test            # Preview all clicks

Typical Setup

Stormtrooper Helmet

1. Mount ESP32-S3 board inside helmet (back or side)
2. Position INMP441 microphone near mouth
3. Connect MAX98357A to helmet speaker
4. Route PTT button to convenient location (chin or external)
5. Load “Trooper” or “Trooper NEW” preset
6. Enable click sounds for authentic comlink effect

Darth Vader Helmet

1. Install components in helmet or chest box
2. Position microphone inside mask
3. Connect to helmet speaker system
4. Load “Vader” or “Vader NEW” preset
5. Adjust ring modulator and reverb to taste
6. Disable click sounds (Vader doesn’t use comlink clicks)

Technical Specifications

Comparison: Voice Changer vs. MCSVS

Use together: The MCSVS transmitter integrates directly with the Voice Changer. Use the same buttons for preset switching, PTT control, and triggering pre-recorded sound files (blaster shots, voice lines) – all while your live voice is being processed.

Limitations

CPU-intensive effects: Some extreme effect combinations may cause audio glitches. The included presets are optimized to avoid this.

Single speaker output: Mono output only. Stereo requires PCM5102A DAC with external stereo amplifier.

Learning curve: Full customization requires CLI commands. Basic use with presets is straightforward.