XILS-lab

Ridiculously expensive and notoriously
unreliable, the Polymoog wasn’t Moog’s most
popular synthesiser, but it certainly remains one
of their most interesting. Released in 1975, it
used the same sort of ‘divide down’ oscillator
design as the electronic organs and string
synths of the day, whereby two high frequency
oscillators generated up to 71 simultaneous
notes through a process of per-note frequency
division. Not only was the high polyphony
enabled by the technique impressive, but it lent
the Polymoog a very particular sound, setting it
apart with its wild pads and strings.
Two years in development, PolyM (VST/AU/
AAX) is an exacting plugin recreation of the
original hardware, including every feature of the
real thing, and a few major additions.
Divide and conquer
PolyM’s two oscillators are designated Lower
and Upper, indicating which section of the split
E0D6 key range each is triggered by. The divide
is set by dragging the pointer above the
keyboard left and right, and various parameters
throughout the instrument diferentiate
between Lower and Upper, making it possible to
program two distinct sounds in a single patch – a
bass at the bottom and a pad at the top, say.
Each oscillator is switchable between saw and
X I L S - l a b
PolyM €149
Virtualising a venerable classic from the mighty Moog, does this quirky
string synth still have a place in today’s electronic music studio?
“Various parameters
diferentiate between
Lower and Upper,
making it possible to
program two sounds”
PULSE WIDTH
MODULATION
Apply PWM to two
keyboard ranges
AMP ENVELOPE
Shape the oscillators in ADSR
or original Legacy mode
WAVESHAPE
Select square, saw
or both for PolyM’s
two oscillators
RESONATORS
A triple resonant
filterbank for
formant shaping
MASTER GAIN
CONTROLS
Mix the outputs of
PolyM’s four filters
MODULATIONS
Assign up to 15 mono and
polyphonic modulation pairings
MODE FILTER
Apply eight preset
‘brightness’ filters,
plus Vox Humana
KEYBOARD
SPLIT
Move the slider to
set the Upper/
Lower divide
24dB VCF
A globall low-pass
filter for Upper,
Lower or both
POLYPHONIC VCF
A software-
exclusive per-note
multimode filter
FM/P M
Apply frequency or phase
modulation to the oscillators
square waves or a mix of both, and has its own
frequency modulation LFO onboard, which
becomes phase modulation when the square
wave is locked to the saw. There’s also
independent PWM for octave 12 and 36. The
concentric Fine Tune/Beat knob independently
tunes both oscillators together and detunes the
saw wave of the mixed oscillator for phasing and
beating, with deeper tuning (+/-6st) and levelling
of the saw applied in the Rank Tune and Rank
Mix sections. Further levelling is done using the
Master Gain Controls, which we’ll come back to,
and Octave Balance sliders, which enable up to
12dB of up/down levelling for each two-octave
keyboard section.
The Loudness Contour section ofers two
styles of velocity-responsive amp envelope: a
Minimoog-style three-stage model emulating
the original design with separate Upper and
Lower Decay settings, and a button for
switching Decay to Release; and a standard
EFFECTS
Activate PolyM’s
effects, edited in
the top panel
92 / COMPUTER MUSIC / January 2018
> reviews / xils-lab polym
CMU251.rev_polym.indd 92 13/11/2017 11:47