Epoch Modular Benjolin
Both the Blippoo Box and the benjolin are based around similar "chaotic cores," which in the the case of the benjolin, is comprised of two vcos and a unique circuit designed by Rob, which he calls a rungler. The rungler is basically an 8 step shift register that takes its serial input from the squarewave of one oscillator and its clock input from the other. The digital outputs of the shift register are than put through a primitive digital to analogue converter to create stepped voltage patterns, which are then wired back into the oscillators. The effect of this arrangement is to create a complex interference pattern that gives the benjolin its unique, aleatoric character.
Along with this chaotic core, the benjolin also includes a 2-pole vcf with a unique topology that imparts an amount of all harmonic distortion to the filter outputs. The eurorack module I have designed has additional modifications not included in the original benjolin circuit, including HP and LP outs for the filter, as well as a rungler loop function that can be controlled either via control voltage, manually with an offset knob and also with a toggle switch that turns the offset on and off. These different controls may also be used in tandem, and all serve in someway to hold the rungler in a looping pattern, allowing one to cut pieces out of the chaos and create repetitive drones and beat-like patterns at whim.
As you can see from the flow chart above, there are 4 CV ins total: one for oscillator A, one for oscillator B, one for the Filter cut off Frequency (Run F) and of course the rungler loop CV already mentioned. The CV inputs of the two oscillators are normalized for cross modulation so when nothing is plugged in the triangle output of oscillator A goes into the input of B and vice versa. Similarly, the filter cut off input is normalized to the triangle output of triangle B. The three normalized CVs each have attenuator knobs.
Outputs include the Pulse and triangle wave outputs from oscillators A and B, the direct output from the rungler, an XOR (which is a logic output from the rungler) as well as a PWM output derived from the Triangle waves A and B. And of course there are also the three filter outputs mentioned above.
A darling of the DIY synth community for years now, Rob Hordijk's benjolin circuit is really like no other synth/noisemaker out there. The benjolin is the smaller sibling of Rob's...
Max Depth: 22mm
Power: 45mA@ +12V , 45mA@ -12V , 0mA@ +5V
is back-ordered. We will ship it separately in 10 to 15 days.