20
RackPack: Transient Designer
Diagram 2 shows the difference between Env 1 and Env 2 that defines
the control voltage of the VCA. The shaded area marks the difference
between Env 1 and Env 2 that controls the control voltage of the VCA.
The amplitude of the attack is increased if positive ATTACK values are
set. Negative ATTACK values reduce the level of the attack transient.
Diagram 3 displays the processed waveforms with maximum and mini-
mal ATTACK to compare against the original waveform in diagram 1.
The SUSTAIN Control Circuitry
The SUSTAIN control circuitry also plays host to two envelope genera-
tors. The envelope tracker Env 3 again follows the original waveform.
The envelope generator Env 4 maintains the level of the sustain on the
peak-level over a longer period of time.
The control voltage of the VCA is again derived from the difference
between the two voltages. Sustain amplitude is increased for positive
SUSTAIN settings and reduced for negative settings.
Technology
Diagram 2: Calculated Control Voltage (Attack)
Difference Env 1-Env 2
(Equals VCA Control Voltage)
U/mV
t/ms
Diagram 3: Processed Waveforms (Attack)
Maximum Attack
Minimum Attack
Original Waveform
t/ms
U/V
Attack Control Circuitry,
Sustain Control Circuitry
