Behringer 921B OSCILLATOR Analog VCO Eurorack Module

The Behringer 921B OSCILLATOR is a faithful analog recreation of the voltage-controlled oscillator found in the legendary Modular 55 and 35 Series synthesizers of the 1970s. Built for the Eurorack format, it places a genuine analog VCO into a modern, affordable module. The oscillator produces four classic waveforms simultaneously—sine, triangular, sawtooth, and rectangular—each available on its own dedicated output jack. This allows a single 921B to feed multiple destinations in a patch, whether driving different filter inputs, creating layered timbres, or providing modulation sources when used in the LFO range.

The module is designed to work in tandem with the Behringer 921A OSCILLATOR DRIVE, which provides a shared control voltage bus for synchronizing multiple 921B units to track pitch together—mirroring how the original system managed polyphonic and multi-oscillator patches. However, the 921B also functions perfectly well as a standalone free-running oscillator or low-frequency modulation source. For synthesists building out a Behringer System 55 or integrating vintage-voiced modules into a broader Eurorack setup, the 921B offers the unmistakable warmth and character of 1970s analog oscillator design at a price point that makes multi-oscillator configurations practical.