Owner`s manual

36
CHAPTER 4 -
Modular Components of the TimewARP 2600
CHAPTER 4 -
ARP 2600, the keyboard control depth was not adjustable.
The second and third
FM Control
inputs are governed by linear attenuators; prewired to
FM Control inputs are governed by linear attenuators; prewired to FM Control
these are the
ADSR Envelope Generator
output and the
ADSR Envelope Generator output and the ADSR Envelope Generator
VCO-2 Sine
output.
Inserting a patch cord at an input jack automatically disconnects the default signal.
4.5
Envelope Generators
The
Envelope Generators
generate transient, positive-going waveforms, with
controllable rise and fall times. They are used primarily with the
VCF
and
VCA,
in
generating events whose time-varying spectrum and amplitude must be accurately
and repeatably controlled. The output from each generator is a positive-going signal
whose rise and fall time is set by slide controls on the generator, and whose onset and
overall duration is determined by a gate signal.
The maximum value that either envelope can reach is +10vV; thus, unattenuated,
either envelope is capable of driving a
VCF
or
VCF or VCF
VCA
from its minimum initial setting
(10Hz for the
VCF,
-l00Db for the
VCA
) all the way up to maximum. See 4.1.2 and
4.1.3, speci cally the data on control input sensitivity. Reread too sections 2.1.6
through 2.1.7.
Gate signals for operating an
Envelope Generator
may originate with a
Envelope Generator may originate with a Envelope Generator
Manual Start
button, the
Keyboard Controller,
or any +10vV square-wave or pulse signal. The two-
position switch just under the lower
AR
generator selects between the two latter
sources.
The Manual Start
button overrides both of these.
4.5.1
ADSR Envelope Generator
The
ADSR Envelope Generator
offers variable
ADSR Envelope Generator offers variable ADSR Envelope Generator
Attack
time, initial
Decay
time,
Sustain
level,
and  nal
Release
time. Four vertical sliders control these parameters: note that three of
these are time parameters and the fourth –
Sustain
level – is not.
The generator produces an output only when a gate signal is present at its input. At the
onset of a gate signal, the output level rises to +10vV, at a rate set by the
Attack
slider.
When the level reaches +10vV, it immediately begins to fall, at a rate set by the
Decay
slider, to a level set by the
Sustain
slider. It remains at this level while the gate signal
continues. Finally, when the gate ends, the output falls to zero at a rate set by the  nal
Release
slider.
If the gate ends at any time during the
ADSR
cycle, the generator immediately advances
to its  nal
Release
phase: the current output level starts falling to zero from whatever
value it had at the moment the gate ended.
When the
Envelope Generator
is controlled from the
Envelope Generator is controlled from the Envelope Generator
Keyboard Controller,
it responds to the
trigger signal from the keyboard – supposing that an envelope is already in process – by
repeating the  rst 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 leading edge of the gate.