The Behringer 921A oscillator driver brings authentic vintage modular synth tone to your Eurorack setup. As an authentic reproduction of the circuitry from the iconic "Modular 55 and 35" oscillator drivers, the 921A lets you harness quintessential sounds used by famous artists on landmark records. Now you can build your own custom, modular synthesizer with vintage character that fits into a standard Eurorack case—at an affordable price.

Authentic Reproduction of Legendary Modular Synth Circuitry

The 921A oscillator driver authentically recreates the original discrete transistor circuitry that gave vintage modular synths their distinctive sound. The recreation is so accurate, you'd be hard pressed to tell the difference between the 921A and an original. Whether you're trying to nail those classic modular synth tones or forge new sonic territory, the 921A provides an incredible foundation.

Eurorack Compatibility for Modular Flexibility

Designed to fit right into a standard Eurorack case, the 921A oscillator driver integrates seamlessly into your modular rig. Mix and match the 921A with other modules to build a one-of-a-kind synthesizer tailored to your creative needs. Go minimal or create enormous rigs—the 921A is ready to drive oscillators however you choose to patch things up.

Adjustable Frequency and Waveform Width

The 921A gives you hands-on control over the oscillator's frequency and waveform. Adjust the frequency knob in either octave or semitone increments and toggle between the two with the rocker switch. You can also adjust the pulse width of the rectangular waveform from a narrow 10% to a broad 90% using the dedicated control knob. This extensive control over the waveform's harmonic content lets you shape your sound.

External Modulation and Control Inputs

On top of the onboard controls, the 921A includes inputs for external modulation sources. Patch in control voltages or other signals into the 3.5mm jacks to modulate either the frequency or waveform width. For even more creative possibilities, the 921A can drive up to 12 921B oscillator modules simultaneously. Layer oscillator outputs to design incredibly complex waveforms.