This is Behringer's circuit accurate clone of the 1979 Kobol Expander made by French company RSF & famously used by Depeche Mode and many others. The original Kobol Expander was a 19" module with the usual VCO & Filters etc, designed to be added to an existing keyboard or triggered via a sequencer or pitch to voltage converter & was pretty unique in that all parameters were adjustable by control voltage including the VCO waveform selection itself!

Two further 'expander units were made in the expander series, one of which added extras like Ring-Mod &Sample & Hold features to patch in and control the VCO unit, while a 3rd expander was the memory storage/recall unit.

Behringer have fully reproduced the Kobol with its seven choices of VCO waveforms which were uniquely continuously variable rather than simply switchable between waveform shapes like most synths. This feature plus full external control of parameters therefore allowed the VCO waveform to be continuously modulated by something like an external LFO.

The Kobol Expander is often referred to as 'The French MiniMoog'  in that they were both early, self-contained & portable 2 Oscillator mono synths using a classic VCO - VCF - VCA signal path, but the MiniMoog was 3 Oscillator with the 3rd Osc' being assignable as an LFO while the Kobol was a 2 Oscillator synth with a dedicated LFO. The other main difference and a feature which made the Kobol very unique was the aforementioned VCO control which can sweep between the seven available waveforms allowing the Kobol to deliver a much wider palette of continuously variable VCO sources which could be externally controlled.

This Behringer circuit accurate clone also emulates the Kobol's 4-Pole filter saturation for which it was also famous.

The Behringer Kobol Expander is Duophonic and like with most of their mono-synth modules you can poly-link up to 16 units.
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