Behringer Kobol Expander


Semi-modular Duophonic analogue synthesizer

  • Replica of the Kobol Expander of the 70s
  • Semi-modular design allows access to all sound generation components via 31 sockets (3.5 mm jack)
  • Analogue signal path: VCO-VCF-VCA
  • 2 Oscillators with 7 waveforms, oscillator synchronisation and pulse width modulation
  • Low-pass filter with resonance (24dB/oct.)
  • LFO with 2 selectable waveforms (triangle, square) and several modulation destinations
  • 2 Envelopes, each with controls for attack, decay and sustain
  • Noise generator
  • Poly-chain function for connecting up to 16 devices
  • External audio input for connecting external sound sources
  • Volume control
  • Can be used as a complete Eurorack synthesiser voice (width: 80 HP)
  • Dimensions (W x D x H): 424 x 136 x 97 mm
  • Weight. 1.5 kg
  • Incl. power supply unit (12V DC2, 1.0A)


  • 1 Audio output: 6.3 mm jack
  • 1 Audio output: 3.5 mm jack
  • 1 Headphone output: 3.5 mm jack
  • 1 MIDI Thru: 5-pin DIN
  • 1 USB port: type B
Available since December 2023
Item number 571630
Sales Unit 1 piece(s)
Design Desktop
Polyphony 2
Sound Generation Analogue
Storage Medium None
USB-port Yes
Effects No
Arpeggiator No
Number of Analog Outputs 3
Digital Output No
Display No
Optional Expansions None
Special Features Eurorack compatible
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Unconventional and rare

With its Kobol Expander, Behringer has revived the analogue synthesizer circuitry of the same name from French manufacturer RSF. The fact that only a small quantity of around 800 units of the original RSF Kobol Expander in 19" rack format was produced in the 1970s resulted in the mono synth leading a mere niche existence and becoming an extremely rare collectible that fetches horrendously high prices on today's second-hand market. Thanks to its unique features, the RSF Kobol Expander offered users far greater versatility than most other analogue synths of the time and soon became renowned for combining excellent sound with an incredibly high level of flexibility. Its semi-modular design, which comprises control inputs for virtually every function and allows the main unit to be easily removed from the chassis and fitted into a Eurorack frame, makes the Expander eminently suitable for combination with other analogue synths, sequencers, or modular systems.

Beyond the standard

The Behringer Kobol Expander may resemble a conventional dual-VCO synth on the outside, but it is packed with unique features inside: Its specially designed oscillators allow particularly smooth morphing between seven different waveforms, which can be swept through without octave switching over the entire frequency range (10Hz to 10kHz) using just a single controller to create particularly impressive effect sounds. The Behringer Kobol Expander also includes an oscillator sync function, independent pulse width modulation for each VCO using a designated VCA, a voltage-controlled low-pass filter with a steep 24dB slope that allows parameters from several different sources to be modulated simultaneously, and a voltage processor that provides enhanced shaping options for both audio and control signals. Alongside CV inputs for parameter controlling, Behringer's Kobol Expander also features numerous audio inputs and outputs that allow effects units to be integrated into the signal chain, e.g. between a VCO and the VCF, or external audio sources to be included into the setup to expand the sonic palette even further.

Behringer Kobol Expander front panel with control elements

For all those who want more

A semi-modular synthesizer like the Behringer Kobol Expander offers way more than just bass and lead sounds. Its true creative potential can be harnessed by exploring the incredibly versatile patching options, which allow users not only to expand the scope of functions by integrating further modulation sources but also to include additional audio signals in various positions in the signal chain for even more creative sonic textures. Thanks to its extensive range of features and excellent sound quality, the Behringer Kobol Expander is the ideal solution for all those who are looking for a mono synth that can reliably take on an extremely wide variety of tasks, particularly when combined with suitable periphery.

Behringer Kobol Expander rear panel with connections
Behringer logo

About Behringer

The company, which was founded in Germany by Uli Behringer and now manufactures its products in China, has been known for affordable and great-value equipment since its very first product, the Studio Exciter F. An array of mixing consoles (such as the Eurodesk MX8000), signal processors, and later sound amplification and monitoring equipment, has made it possible for countless musicians to fit out their home studios, practice rooms, and mobile PAs within budget limits that were previously unthinkable. The acquisition of other companies, including Midas, Klark Teknik, and TC Electronic, meant that new product groups were added - and also resulted in the technical expertise of these companies being incorporated into product development.

A highly versatile tool

The Behringer Kobol Expander synth offers a wide range of sonic possibilities for transforming its rich basic tones into unique soundscapes with additional grit and character as well as plenty of presence. For example, users can also use the voltage processor as a mixer with a slight overdrive effect for the oscillators, integrate a simple FM patch between the VCOs via a few patch points and select whether the dual oscillator signal or just the carrier signal is subsequently sent to the filter, or modulate the amplitude within a wide range of frequencies from tremolo to audio using the separate VCAs. And the Behringer Kobol Expander's oscillator sync and filter FM functions allow the sounds to be further enhanced after patching to create virtually unlimited variations. It is recommended that the user record the individual tones they have created as percussion or effect elements in order to be able to add them to a track using a DAW or a sampler later on.

45 Customer ratings

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32 Reviews

Another unique Classic
Elektroboots 20.12.2023
This is one synth that i thought id never get to own, or even get this version soon, luckily spotted this in stock on here and grabbed one( thank you Thomann!) .like the rest of the Behringer synths this doesn't disappoint although ive no way of comparing it to an original i have watched online comparisons of the other synths that are spot on .the quality is great and has a really unique sound !AND at a great price point you can't complain at that .Thankyou Behringer!


Pure fun and sound satisfaction, for a price hard to believe
Robotique 14.02.2024
I've, like most of us, never played a real RSF Kobol Expander (the 19" rack synth this is based on), but it surely sounds wonderful. Warm, fat, raw and when patched up, extremely vivid and weird/wild.

With the additional rack ears, I've mounted it with my other semi-modulars. At the moment I'm trying to figure out how to make space for yet another Kobol Expander. The two of them will surely make a great team, in unison or duo mode, patched in between the both units.

A must-buy if you want something extraordinary.


K0b0L L0v3r! Expand Me!
CovilStudio 10.06.2024
The Behringer Kobol Expander is a modern take on the classic RSF Kobol Expander from the late '70s. This semi-modular analog synthesizer has garnered synth nerd's attention for its unique features and affordability. The Kobol Expander stays true to its roots with a semi-modular design that features 32 Eurorack patch points. It offers direct and real-time access through its 31 controls. Amazing honey drop sweet Dual VCOs capable of smooth morphing between seven waveforms, providing a wide frequency range (10Hz to 10kHz). These oscillators include sync and PWM functionalities, besides a 24dB low-pass filter known for its natural and immersive saturation. It also features an analog LFO, noise generator, and voltage processor for enhanced sound shaping​!

The Behringer Kobol Expander is an excellent choice for those looking to delve into modular synthesis without breaking the bank. Its blend of classic design, modern features, and extensive modulation capabilities make it a essencial addition to any synth Nerdenthusiast's setup​!

Tip: control Kobol by Cv/Gate with a 303 and you'll see what liquid Acid is!!!! :) ;)


No Brainer
The Curator 22.01.2024
I can write a long story here, but 200,- for as far i know a full discrete module is grazy. I even get low end while resonance on full in certain settings. Recomended!


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