The Opus was a very 'novice-friendly'
polyphonic synth released in 1980 that offered three sounds simultaneously
thus you could layer strings, organ and brass. The polyphony was,
like the ARP String Ensemble and other string synths, derived from
'divide-down' electronic organ technology and so was totally polyphonic.
However, its limitation was that there was just one filter and envelope
to service all voices and so it was necessary to modify your playing
technique to articulate sounds correctly. Whilst this may seem like
a big limitation, it was common for this kind of synth at the time
The string section was made up of a sawtooth wave that
passed through quite a comprehensive multi-mode (but static) filter
for tonal modification and an envelope shaper. The 'ensemble' sound
was created using a multi-stage chorus unit.
The organ section featured variable drawbars that allowed
a great range of organ sounds to be created. This could also also
be passed through the chorus unit to add a kind of 'leslie' effect.
Finally, the brass section (again, using the same basic
sawtooth wave as the string sound) had a filter section and simple
envelope generator that you could use to create brass and simple
All three sections could be mixed and (unusually for
the time) panned allowing you to stack up a huge stereo sound. Each
section was also colour coded (red for strings, green for the organ
and yellow for brass) which made it very easy to use even without
much (or any) experience.
The Opus also featured a dynamic resonant lowpass filter
with its own simple AR envelope generator and the strings and/or
the brass could be routed to this for greater tonal variation and
the creation of rudimentary synth sounds.
Like other Moog products of the time, however, it was
not a huge success. The Prophet 5 and Oberheim polysynths were dominant,
Moog came too late to the market with the Opus and it offered nothing
new - remember that Elka, Crumar, ARP and others had had similar
products like this out for several years by the time the Opus was
released. However, it was a fine sounding keyboard and the string
sound was particularly lush.
This donation comes from Akai Z4 user, Paul Marshall,
who has meticulously sampled the string sound from his own Opus
at every major third across its 4-octave keyboard range. He has
sampled the Opus's two footages (8' and 4') separately and whilst
Paul could have taken the easy route and simply layered these samples
to create a combination of the two footages, instead, he has painstakingly
sampled the Opus's original 8' and 4' combination for a truly authentic
sound. Each sample is around five seconds long with long, seamless
loops which have been carefully hand-converted to Kompakt for Nostalgia.