We developed a portable amplifier for an electric guitar with an integrated speaker that also functions
as a Bluetooth speaker. The device is small, battery-powered, and features mechanically adjustable
rotary knobs for tone and sound control, a distortion on/off switch, and a mode selector switch. Every
electric guitar requires an amplifier to enhance its sound and project it to an audience. By adding toneshaping controls, the instrument becomes versatile across different musical genres.
The guitar signal is captured via an external analog-to-digital converter and sent digitally to an ESP32
microcontroller. The clean signal is routed directly to an external combined digital-to-analog converter
and class-D amplifier, or optionally passed through a distortion effect that adds the characteristic “fuzzy”
tone. An onboard digital sound processor applies digital filters set by the rotary knobs to boost or cut
specific frequency bands before final amplification and playback through the speaker.
In Bluetooth speaker mode, the ESP32’s built-in Bluetooth acts as a receiver for streamed music. The
incoming audio is transmitted digitally to the amplifier, with all digital filters bypassed so playback
matches the source device’s output.
The device runs on a battery pack sourced from a Makita cordless power tool.
I developed the firmware in Visual Studio Code specifically for the chosen analog-to-digital converter,
digital-to-analog converter and ESP32 configuration.
We are very satisfied with the final product. It meets all our expectations, inspires future projects, and
validates the knowledge we gained during our studies.
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