ARP 2600 - Envelope Generator

34
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put
immediately begins to decrease,
at
a
rate
determined
by
the
setting of
the INITIAL DECAY
control,
to
a
level
governed
by
the SUSTAIN
level
control
The
output
voltage wit!
remain
at this
level
as
long
as the GATE signal
remains
at
the generator
input. When
the
gate
signal is removed, the
output voltage
returns
to
zero
at
a rate determined
by
the
FINAL
RELEASE
time
con-
trol.
If
the
GATE
signal is removed
at
any
point
during the envelope,
the
output
voltage immediately
begins to
decrease
to
zero
at a
rate
de-
termined
by
the setting
of
the
FINAL
RELEASE
time control.
When the envelope generator
is
controlled from the
3604
key-
board controller,
it responds to
the TRIGGER signal
from the
keyboard-
supposing that
an
envelope
is
already
in
process—
by
repeating the first
two
stages
of an envelope and returning again to the SUSTAIN
level.
For
all other
control
gates
presented
to
the
generator
input, circuitry
internal
to the generator itself
derives
a
TRIGGER signal
from the
lead-
ing edge
of
the
gate.
4.312
The lower
ENVELOPE GENERATOR
offers controllable
ATTACK and RELEASE time.
When
a
gate
voltage
is
presented to the genera-
tor input, the output
voltage
rises,
at a rate
deter-
mined
by
the
setting
of
the ATTACK
time con-
trol,
to
+
10V. It remains
at
that level until the
gate
voltage is
removed, at which time it
falis
to zero at a
rate
determined
by
the setting
of
the
RELEASE
time
control.
If the
gate signal is
removed before the out-
put voltage
has
risen all
the
way
to
+1
0V, the
output
voltage will immediately
begin to
fall
to
zero
at
a rate
determined
by
the setting
of
the
RELEASE time control.
The A/R
generator does
not require a
triggering signal.
Its action
is in
fact
very similar
to that
of
the lag processor
(see
4.53),
except that
the
latterdoes not
offerseparately
controllable
rise and
fall times
for
its
output
voltages.
I
I
attach
i
-HOY
OUTPUT
Tif*l£
GATE