Behringer Kobol

The Behringer Kobol Expander is a duophonic analog semi-modular synthesizer based on the RSF Kobol Expander, a French-built instrument from 1979 of which fewer than 200 were produced. Behringer’s recreation keeps the all-analog signal path intact: two VCOs that sweep continuously through seven waveforms including sawtooth, square, pulse, and variable pulse, with oscillator sync and pulse-width modulation across the full 10Hz to 10kHz range. The filter is a 24dB four-pole lowpass design that reflects the character of the original, known for a particular gritty saturation that reads differently from most Moog-derived ladder filters.

The Kobol Expander ships with 32 Eurorack-compatible patch points, making it usable as a standalone desktop synthesizer or as a patchable module in a larger modular setup. It includes an external audio input, a noise generator, two ADS envelopes, and an LFO with two selectable waveforms. MIDI in/thru and USB connectivity are on board, and Behringer’s Poly Chain system allows up to 16 units to be linked for polyphonic operation. For producers who work with Eurorack or want the specific character of the Kobol filter without hunting down a rare original, it covers the brief.