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Was it a true synthesizer and was it really polyphonic? The Polymoog used divide-down twin oscillator
circuitry, (with relative detune) which wasn't dissimilar to that employed
in string machines and electric organs. To some this meant that it didn't
have the "characteristic" Moog sound and was somehow thinner and
not the "real deal". Once again, the derisory battle cries from
those expecting a polyphonic Minimoog. As previously mentioned, this wasn't
Luce's intention...
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So what
was it capable of? Both oscillators
could be detuned against each other and the Polymoog offered sawtooth and
pulse/square waves, (although limited to certain keyboard split zones). In
addition pulse width modulation was also available. Oscillator 1 was ramp
only and could be switched to 8' and 4' ranges and oscillator 2 was
variable pulse and was switchable between to 16' and 8' ranges. The
oscillators could then be passed through what Moog rather grandiosely
referred to as "Resonators". In fact it was really just a three
band equaliser but with variable gain, frequency and resonance (similar to
a parametric). The Polymoog also had a 5 channel mixer on the control panel
for the direct output of the preset, filter, resonators and the lower and
upper halves of the keyboard - providing facilities to layer each section
of the sound. In addition, each section had a separate output for external
processing. The Polymoog had ample output options; Trigger outputs
controlled external monosynth's and there were three inputs that allowed
you to pass an external sound source through the Resonators and the VCF.
So what about the "presets"? Once again this was a misconception. Luce
claimed that the Modes, (remember - he didn't call them presets) were
supposed to be a "starting point". For instance if Piano was
selected, this would be set up to offer the correct percussive envelope and
tone of a piano sound but then the operator was supposed to then use the
VAR mode to modify the sound to taste with the synth section. What made the
Modes different from simple presets derived from the front panel controls
was that each mode was generated by dedicated chips containing 142 circuits
known as articulators.
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The articulators consisted of 71 amplifiers and 71 filters that
shaped the sound from the oscillators. In effect the articulators contained
the fundamental timbre of each sound. This clearly explains why some of the
new "presets" available on the 280a Polymoog Keyboard were
difficult or impossible to reproduce on
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the original
203a, simply because the dedicated articulator circuits were not available
in the 203a.
As I
mentioned earlier, Polymoog's had a Moog ladder filter but there was only
the one so this part was technically monophonic. The filter did offer a
dedicated ADSR, variable cut off, resonance. In addition, it also provided
two modulation sources, (LFO and Sample and Hold). There was also a
separate velocity sensitive VCA and envelope for each note so it was
polyphonic, well, kind of…
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Depending on the trigger option selected, when
sustaining a chord and then playing an additional note, the new note would
either trigger all of the other notes being held, or would have no filter
articulation. If it was played using the "Mode" output and the
controls were left in their "Pre" states, you could actually play
it in true polyphonic fashion. In practice though, you would almost
certainly use the final VCA, VCF and Resonators, which would produce what
would be more accurately described as "Paraphonic". I believe
this is because compromises had to be made. As if the Polymoog wasn't
already expensive, bulky and complicated enough… to add a separate filter
and envelope for all 71 notes would have been unviable, not to mention an
immense physical challenge. Corners invariably had to be cut and rather
than offer limited polyphony found in the 4, 6 and 8 voice polysynth's that
were just around the corner, Luce decided to use the divide-down dual
oscillator method to achieve his objectives... the worlds first fully
polyphonic synthesizer. Whether
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he accomplished this or not is a matter of divided opinion but...
yes! all 71 notes on the Polymoog can play simultaneously, something which
is still rare even now, 30 years later.
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