Built around an ESP32-S3, GrvEP is a publicly documented portable synthesizer and drum machine that packs a remarkably broad sound palette into a compact DIY design. Its 32-key grid, joystick, seven potentiometers, OLED display, and addressable LEDs provide hands-on control across more than 30 modes, including drum sequencers, subtractive, FM, wavetable, granular, TB-303-style, sampler, and experimental generative instruments.
The modular wavetable mode combines two oscillators with independently morphable AMY wavetable positions, an LFO, and a shared filter. Samples can be loaded from an SD card, while visual tools include a scrolling spectrogram waterfall and real-time EQ display. The project also includes desktop, Android, and WebAssembly simulators for development and testing without the physical hardware.
GrvEP is documented as a prototype hardware project by Clement Chupin, documented in the SynthBox repository rather than presented as a conventional manufactured product. Its firmware is built for the ESP32-S3, with USB and SD card connectivity, and the repository includes resources for building the hardware version as well as companion simulator applications.
