PolyUAnalog: A Modular and Scalable Open-Source Architecture for Polyphonic Analog Synthesis

This paper describes the design and implementation of PolyUAnalog, a modular and open-source polyphonic analog synthesizer. The architecture utilizes the AS3397 analog voice chip, with each voice managed by a dedicated RP2040 microcontroller. System coordination, including MIDI processing and voice allocation, is handled by a central conductor board communicating over an I²C bus. Technical implementation details and associated measurements are provided regarding real-time DCO pitch stabilization via a PID feedback loop and the generation of high-resolution control voltages using filtered Pulse Width Modulation (PWM). The complete hardware schematics and C++ software stack are documented to facilitate replication, modification, and further development within the electronic musical instrument community.