INTRODUCTION:
The
benjolin
is
a
multifunction
synthesizer designed by Rob Hordijk.
The module consists of four separate
function blocks: two VCOs, a state
variable filter and an additional circuit,
invented by Hordijk himself, called a
rungler. This particular arrangement
emerged from Hordijk’s efforts to design
a synthesizer that was, as he puts it,
"bent by design". As such, the module
functions according to principles of chaos
theory, where short to long sputtering
patterns
spontaneously
transform
themselves, at times, gradually, at
others, quite suddenly, morphing into
new pattern doublings and bifurcations.
The chaotic character of the benjolin is
anchored in Hordijk’s rungler circuit. In
essence, the rungler is an 8-step shift
register that takes its data input from one
oscillator (OSC A) and its clock input
from the other (OSC B). The output of
the shift register is then fed into a
primitive, digital-to-analogue converter,
creating a stepped voltage pattern of
variable length and depth, what Hordijk
terms a “stepped havoc wave”. This
rungler wave is then wired back into the
oscillators, via the attenuator knobs (Run
A and Run B), creating the complex
interference system that lends the
benjolin its unique, aleatoric character.
The inclusion of a voltage-controlled filter
expands these possibilities further into
the audio realm. Its design includes
Hordijk’s signature, Z-plane modulation
circuitry, which produces an all-harmonic
distortion, lending the filter a kind of
warm, organic character—reminiscent of
that classic tube amp sound. This
distortion is most palpable when the
resonance of the filter is turned to the
maximum, with both oscillators running in
the audio range.
The filter’s input is a mix of a PWM wave
(derived from the triangle waves of each
oscillator) and the rungler signal itself.
And as with each of the oscillators, a
rungler attenuator (RUN F) allows
modulation of the filter as well.
To round things out, CV inputs for both
the oscillators and filter are normalized,
each via their respective attenuators.
This allows for cross modulation between
the oscillators and a “sweeping” effect for
the filter, hitched to Triangle B.
Module Width: 18hp
Module Depth: 22mm
Current draw: ~45 mA@+12V
~45 mA@-12V
Summary of Contents for Benjolin
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