The Quadra is a DIY beat box based on a custom-designed PCB and powered by an ESP32 microprocessor running software using my M16 audio synthesis library. The PCB includes space underneath for an I2S audio DAC and amps for connected loudspeakers, with interface controls and LED display on top. The name Quadra derives from its organisation into four musical parts – lead, arpeggio (harmony), bass, and drums. Each part consists of a sound (or sounds) and a 16 step sequence. All parts are synthesized in real time, and controls manage performance and programming changes. As per my interests, many of aspects of the Quadra are algorithmically generated and controlled but plenty is left up to live interaction.