Macumbista Butterfly Benjolin

The Benjolin is a standalone synthesizer designed by Rob Hordijk from the Netherlands. It contains two oscillators (one LFO and one VCO), a voltage controlled filter and a circuit called a “Rungler”, which allows chaotic cross-modulation possibilities between the different parts of the circuit. Hordijk refers to the Benjolin as a circuit which has been “bent by design.”

The double version, which I have named the Butterfly Benjolin, allows incredible amounts of chaotic cross-modulation between the two halves of the instrument.

These hand-made Macumbista Benjolins have been further customized with a patchbay, which can be used to interface with other modular synthesizers or to setup further control voltage feedback systems within the Benjolin itself, attenuators on the three control voltage input and LEDs displaying the internal state of the Rungler.

The latest Macumbista Butterfly Benjolin V3 instrument has been redesigned during the spring of 2019 in collaboration with Pete Hartman of Frog Leg Synthesis. The filter input has been improved, and the main output of the instrument buffered for lower noise and ease of use with a wider range of mixers and DI boxes.

The wooden enclosures used to create these handmade analog synthesizers all date from the 1960’s and 1970’s. There are individual variations in the exact color, the size, and the marks which history have left upon them.


The patchbay of these Benjolins has banana jack connections for the square and triangle waveforms of each of the two oscillators, the Pulse Width Modulation output of the two oscillators, the Rungler output, the XOR (exclusive/or) logic operation of the two oscillators and the output of the filter.

There are also banana jack control voltage inputs with attenuators for the frequency of each of the two oscillators and the filter cutoff frequency. The layout of the panel is designed to be both intuitive and playable (unlike many EuroRack modules, for example…). And finally, the three output bits of the Rungler have been visualized with red, green and blue LEDs.

All Benjolins use Neutrik 6.3mm (1/4″) Filter input and Audio output jacks, an additional GROUND banana jack to interface with other modular systems and a universal 12 V DC “wall wart” power supply.

These Benjolins are produced under licensed agreement with Rob Hordijk.

A basic user’s manual can be found here.


The price of the Butterfly Benjolin V3 is EUR 1065, plus shipping costs. All my instruments are made-to-order. Contact for availability:

MACUMBISTA at-the-domain GMAIL dot COM. Thank you for your kind attention.


The Butterfly Benjolin V3 contains the following modifications from Hordijk’s original Benjolin circuit:

BUFFERED OUTPUT: to get a signal to the 6.3mm (1/4″) output jack on the back on the instrument, one of the output signal banana jacks must be patched to the black OUTPUT banana jack. Typically this if the FIL output, but other output signals can be used if you are careful with the Volume levels. This signal is attenuated by the VOL knob and buffered before sending to the 6.3mm output. (Some previous versions of my Benjolins did not have this output buffered.)

LOOP SWITCH: The LOOP switch locks the otherwise chaotic pattern of the Rungler into a loop. The LEFT position is a loop of 4 steps going forward, the MIDDLE position is the normal chaos of the Rungler, and the RIGHT position is a loop of 4 steps forwards and 4 steps backwards.

EXTERNAL INPUT SWITCH: The external input 6.3mm jacks on the back of this Benjolin allows signals from another source to be sent through the Low Pass Filters of the instrument. Selecting EXT on the FIL INPUT switch sends this signal to the FIL input, where the cutoff and resonance controls of the filter can be used to affect it. When the FIL INPUT switch is in the INT position, the PWM signal, mixed with a small amount of RUN voltage, is sent to the FIL (this is the normal Benjolin signal path).

EXTERNAL RUNGLER CLOCK:: banana jacks on the back panel of the instrument provide switchable clock sources for the Runglers of the instrument. The EXT switch position clocks the Rungler from OSCILLATOR 2 of the instrument, the INT switch position clocks it from the external clock input.


Rear view Butterfly Benjolin V3

Duelling Benjolins from macumbista on Vimeo.

Two Benjolins cross-patched to modulate each other function identically to the Dual “Butterfly” Benjolin.

A Static Environment for Complementary Instabilities from macumbista on Vimeo.

This long-take shows an example of symmetrical cross-patching between the two halves of the Butterfly Benjolin, and gives an idea of the self-modulation possible with this dual instrument.

The following images show a previous panel design for the Butterfly Benjolin V2:

Your humble instrument builder in his old Berlin studio in 2016: