Project
| # | Title | Team Members | TA | Documents | Sponsor |
|---|---|---|---|---|---|
| 60 | Digital Pitch Shifter for Guitar |
Eric Moreno William Chang Zhengjie Fan |
Shengyan Liu | proposal1.pdf |
|
| # **Digital Pitch Shifter for Guitar** Team Members: - William Chang (wqchang2) - Eric Moreno (emoren40) # **Problem** Guitarists without access to a tremolo system face significant limitations in their ability to create expressive vibrato and pitch-bending effects, which are essential for adding emotional depth and dynamic variation to their playing. Without these techniques, the guitar’s sound can feel static or restrained, especially in genres like rock, blues, and jazz, where pitch manipulation is crucial. Traditional tremolo systems, though effective in addressing this issue, require invasive modifications to the guitar body, such as routing or altering the bridge. These changes not only compromise the guitar’s original design but can also affect its sound and value. Additionally, such systems may not be suitable for all playing styles, or for guitarists who prefer a more minimalist approach. As a result, players seeking greater versatility in their instrument face the difficult choice between sacrificing their guitar’s aesthetics or settling for limited expressive capabilities. This is the gap the proposed project aims to fill. # **Solution** The solution to the aforementioned issue is a compact, attachable digital pitch-shifting device that uses a sonic sensor to detect the proximity of the guitarist’s hand to the bridge of the guitar. As the player moves their hand closer or farther from the sensor, the pitch of the guitar signal is dynamically adjusted, allowing for real-time pitch shifts up or down. This enables the guitarist to perform expressive techniques like vibrato and pitch bending, similar to those provided by traditional tremolo systems, but without the need for invasive body modifications. Additionally, the device includes a switch or button that lets the player toggle between upward or downward pitch shifts, offering greater flexibility in controlling the pitch. This lightweight solution enhances the player's creativity while preserving the guitar’s natural design and playability. Furthermore, the additional buttons or switches can enable further effects such as reverb, chorus, or delay, giving the player more creative control over their sound. These augmentations enhance the guitarist’s ability to experiment with a wider range of tones and textures without needing to modify the guitar's body or permanently alter its design. # **Solution Components** **Sonic Sensor** The HC-SR04 ultrasonic sensor will play a crucial role in detecting the proximity of the guitarist’s hand to the sensor, which will then be used to adjust the pitch of the guitar signal. The sensor operates using two primary pins: the Trigger pin and the Echo pin. The Trigger pin receives a pulse signal from the ESP32 to initiate the emission of an ultrasonic wave, while the Echo pin sends back a signal to the ESP32 that is used to calculate the distance based on the time it takes for the wave to return. This distance will dynamically influence the intensity of the pitch-shifting effect. **Guitar Preamp** A guitar preamp pedal will be placed between the guitar and the microcontroller to boost the guitar’s signal, which typically ranges in the hundreds of millivolts. The preamp will increase the signal to a level suitable for the ESP32's ADC, ensuring that the microcontroller can properly process the audio input. **Microcontroller (Audio I/O, Signal Processing, Sensor I/O)** The ESP32 microcontroller will serve as the central unit responsible for managing both the input and output of signals, as well as performing real-time signal processing for the project. One of its primary roles will be handling audio input and output through its ADC (Analog-to-Digital Converter) and DAC (Digital-to-Analog Converter) pins. The ESP32 will convert the guitar signal from analog to digital using the ADC, process it with pitch-shifting algorithms, and then convert it back to analog using the DAC for output to a guitar amplifier. In addition to audio processing, the microcontroller will interact with the HC-SR04 ultrasonic sensor by sending a trigger pulse through its GPIO pin to the TRIG pin in order to initiate a reading. It will then read the output of the Echo pin to calculate the distance between the sensor and the player’s hand, which will influence the pitch-shifting parameters. Furthermore, the microcontroller will manage user interactions such as toggling effects or adjusting parameters using additional GPIO pins connected to buttons or switches. **Guitar Amplifier** A 7-watt combo amp will be used to amplify and output the pitch-shifted guitar signal from the ESP32 to an audible level. After the microcontroller processes the audio and applies the pitch shift, the combo amp will boost the signal, making it loud enough for the guitar speaker to produce sound. **Power System** The power management system will use a 5V power supply to ensure stable operation of both the ESP32 microcontroller and the HC-SR04 ultrasonic sensor. Since the ESP32 requires 3.3V, a voltage regulator will step down the 5V supply to provide a stable 3.3V output for the microcontroller. The HC-SR04 sensor, which operates at 5V, will be powered directly from the same 5V supply to ensure proper functionality. A common ground will be shared between all components to maintain reliable communication. Additionally, since the HC-SR04’s Echo pin outputs 5V, a voltage divider can be used to step down the signal to a safe 3.3V for the ESP32’s GPIO. # **Criterion For Success:** - Non-Intrusiveness – The device must attach to the guitar without requiring permanent modifications, preserving the instrument’s original design and functionality. - Real-Time Pitch Control – The pitch of the guitar signal should shift dynamically (range of 2 octaves) in response to the player’s hand movements, ensuring smooth performance. - Adjustable Pitch Direction – A switch or button should allow the player to toggle between shifting the pitch up or down, providing flexibility. - Maintain Guitar Signal Integrity – The device must process the guitar’s audio cleanly, maintaining tonal quality without noticeable latency or unwanted distortion. - Compact and Lightweight Design – The attachment should be small and light enough to avoid interfering with playability or altering the guitar’s balance. - Reliable Power Source – The system must have a stable and efficient power supply, ensuring consistent performance without frequent battery replacements or power interruptions. - Expandable Features – The device should support additional effects like reverb, chorus, or delay through buttons or switches to enhance creative possibilities. |
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