Behringer Kobol Expander, replica of a weird French analog Synthesizer, ready for pre-order for 199€

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According to a new Facebook post, Behringer is working on an analog clone/replica of the Kobol Expander Synthesizer from 1979, for Eurorack.

In April 2022, Behringer announced a clone/replica of the super rare French RSF Kobol Expander Synthesizer. Now the project is finished, and you can officially pre-order. All this for a very affordable price of 199€.

Behringer’s Kobol Expander is noticeably smaller than the original and comes as a Eurorack synth voice module, so like Neutron, K2- etc.

Behringer Kobol Expander

Official Features

  • analog duophonic Synthesizer with two VCOs and seven morphing waveforms
  • authentic reproduction of original “Kobol Expander” circuitry from the ‘70s
  • semi-modular design with a pure analog signal path (VCO, VCF, and VCA)
  • dual oscillators with seven waveforms, oscillator sync, and PWM
  • unique 4-pole VCF for natural saturation only found in Kobol synthesizers
  • analog LFO with two selectable waveforms and multiple destinations
  • additional noise generator
  • 32 Eurorack-friendly patch points for advanced modular connection
  • 31 controls gives you direct and real-time access
  • external audio input for processing external sound sources
  • 16-voice Poly Chain option
  • Comprehensive MIDI implementation with MIDI channel and Voice Priority selection


Article From April 11th, 2022

The Behringer teams are working on a lot of projects. We recently saw a large swing, including many very small instruments starting at $49. Today the next project became public via their official Facebook page.

They announced a clone/replica of the French RSF Kobol Expander analog synthesizer from 1979.

Behringer Kobol Expander

Behringer Kobol Expander

As I report in March, Behringer is also working on a clone/replica of the Kobol keyboard analog mono Synthesizer from 1979. This is now the expander that came onto the market in 1979. This was the patchable version with some neat extra features.

It looks like the Behringer Kobol Expander is a 1 to 1 replica/clone of the original. But in Eurorack format and with the almost legendary MIDI socket on the front panel.

Original Specs

The original RSF Kobol Expander from 1978 featured two 2 VCOs featuring triangle, square, saw, and pulse. One highlight of the original were the capability to morph from one to another waveform. These are joined by a 24dB lowpass filter, two ADS envelopes, a multi-wave LFO, and a VCA.

Unlike the keyboard version, it didn’t feature the 16 memory slots for recall patches and the 2×8 steps sequencer. Plus, it had note on/off and CV/gate controls over most of the parameters. Also, it allowed the processing of external sounds through the Kobol filter and envelopes too.

Behringer Kobol Expander

Expander I Or II?

It would be interesting to know which Kobol Expander Behringer is reproducing here. The Expander 2 was the more exciting because it had more functionality, including ring modulation, sample-and-hold, and envelope followers, as well as extra VCA and LFO modules. The second version would be very welcome.

On the backside, you will find a mono audio output, MIDI thru with a MIDI routing matrix, a USB connection, and a power supply input with an on/off button.

Behringer Kobol Expander backside

Original Sound Demo

The RSF Kobol Expander was a very special “weird” analog Synthesizer. Based on the Minimoog but with a very unique snappy sound and touch. Very curious to hear how close Behringer can get to the sound of the Kobol.

Behringer Kobol Expander is available now for pre-order for 199€.

More information will follow here: Behringer. 

Available at my partner 

Hardware Synthesizer News


  1. would love to see both Expanders for the MonoKobol. the 2nd one has lots of useful CV utils. And of course the big old Poly Kobol toback it up with.

  2. I like that it has CV inputs for the envelope stages. Between this and Victor, Behringer has been on a (modular) roll this week.

    Uli, now set ALL of it aside and fast track that VCS3 clone bby

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