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notes to "glide" from one pitch to the next. This effect is known as portamento or glissando. The Dual
EnvVCA can perform this effect by patching the step-wave into the Follow jack and taking the output
from the Env Out jack. The amount of glide effect is controlled by the rise and fall times. If you're
patched into the pitch input of a VCO, you can adjust the tuning with the Level and Offset pots. Keep in
mind that the Dual EnvVCA is not designed to be a precision portamento effect, so tuning will not be
accurate over a wide range.
Creating ASR and ADSR Envelopes
Cycle on
Cycle off
Rise
Rise/Fall
switches to
Med/Med.
Channel A
Sliders to
taste
Channel B
Rise sets
Sustain time.
Rise+Fall
sets tempo
Trigger
From sound
source
To mixer/
output amp
Audio A
Alternatively, you can use a keyboard instead of Channel B's EOF jack. Patch the gate output into
Channel A's Trigger and Follow jacks. Tapping a key quickly will result in a staccato note, while holding
the key down longer will result in a longer note. Keep in mind that the minimum note length will always
be determined by Channel A's rise and fall time parameters, no matter how short the gate input is.
Another alternative instead of the EOF jack or a keyboard, is to use the gate output of a sequencer that
has control over the gate length (pulse width). Setting longer gate lengths for certain notes will
emphasize or accent them in the sequence. If you don't have pulse
width control on your sequencer, you could patch it into Channel B's
Trigger jack and turn off Cycle.
This patch works because we patched the gate into both the Trigger
and Follow jacks. The Trigger jack ensures a complete envelope
will output even if the gate width is very short. The Follow jack
produces the sustain. If we had just patched a gate into the Trigger
jack, the envelope would start to fall once the peak is reached and
we would have no sustain. However, if the gate at the Follow input
is still high, the envelope will remain high, creating the sustain
portion of the envelope. On the other hand, if we had only patched
Slow
Cycle
Med
Fast
Fall
Slow
Level
ENV
OUT
Fast
A
Rise
Fall
Offset
Time CV
Rise
Fall
EOR
Follow
In
Out
A
OR
VCA CV
Env
Out
Dual EnvVCA
Slow
Med
Fast
Rise
Fall
Slow
Level
Fast
B
Rise
Fall
Offset
Time CV
Rise
Fall
Trigger
EOF
Follow
A
In
Out
B
VCA CV
Audio B
Page
16
of
20
ASR Envelope
An ASR (attack-sustain-release)
envelope is trapezoidal, with a rising
slope (attack), a flat plateau
(sustain), and a falling slope
(release). See Figure 7. The width of
the sustain stage is controlled by the
width of the gate input: holding the
gate high longer results in more
sustain. This is in contrast to an AR
(attack-release) envelope, which is
the triangular shape that results
from patching into the Trigger jack
or using the Cycle button.
One channel of the Dual EnvVCA
can be used to generate a variable
pulse width, and the other generates
an ASR envelope. Turn Channel B
Cycle on and patch the EOF output
to the Follow jack and the Trigger
jack, using a mult or stacking cable.
Patch an audio sound source into
the Audio In jack, and run the
Audio Out jack to a mixer or amp.
Make sure Channel A's Cycle is off.
Set all four Rise/Fall switches to
Med. Adjust the sliders so that
Channel A's sliders are lower (faster)
than Channel B's. Now adjust
Channel B's Rise and Fall sliders to
control the overall tempo, and the
Rise slider alone to control the
length of the Sustain portion.
Figure 7: ASR patch: Gate length
controls sustain length
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