Quadra & Expander Manual
Functions and Envelopes
While envelope generators may not seem as exciting as other modules like filters, oscillators,
and effects, they play a critical role in creating movement and life in a patch. If you come from a
more traditional synthesizer background, all this talk of function generators and
Quadrature
mode
may seem overwhelming. Or perhaps you find it strange that we talk about the Quadra as
an envelope generator but then do not mention the most common envelope type — the ADSR.
This is because the design concept of the Quadra is inspired by what is commonly referred to
as “West Coast” synthesis concepts (a nod to Don Buchla, a pioneer in synth design from
California). You can think of each function generator in the Quadra as a simple envelope
generator. However, since the Quadra can also create very complex looping LFO shapes in
Quadrature mode
, or create complex interacting combinations using the
OR
outputs, we use the
more traditional name of “Function Generator”.
You can use the Quadra on its own as four AD or ASR envelope generators. If you are not
using a traditional keyboard controller AD mode is preferred by many since it is independent of
the incoming gate times. Once the AD is triggered, it will move through its stages until
completion. This is ideal for sequencer or random based patches. You can use the Expander
CV inputs to control the decay time which is like controlling the gate time at the sequencer, but
has a different sound.
Why would you use so many envelopes? If you consider the average synthesizer voice needs at
least two envelopes, one for final VCA, the other for filter cutoff, it is not hard to imagine in a
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