Studio Electronics Boomstar - Manual (Page 19)

Studio Electronics Boomstar Manual 15 Panels
The ENV DEPTH (Envelope) knob sets the depth of the modulation amount
as it is applied to the filter cutoff frequency. The shape of the filter
envelope is determined by the contouring controls attack, decay, sustain,
and release; the amount or depth of the envelope contouring is
determined by this parameter. Note: If the MASTER / DRONE switch is set to
the Master position, then the filter frequency is modulated by ENV 2 , not
ENV 1 .
The MOD DEPTH knob sets the modulation amount of the filter by either VCO 2 (Voltage Controlled Oscillator 2), or LFO
(Low Frequency Oscillator), via the switch to its left. Oscillator 2 becomes an LFO when its range switch is set to its LO
position; in the higher range settings (8, 4, 2) audio frequency modulation (think vocal and metallic timbres/x-mod)
are achieved. The software-based LFO with its versatile, multiple waveforms can be synced to MIDI. [See pp. 17-18,
5.2.10]
5.2.7 ENV 1 - Envelope 1
A
word about the Filter Envelope:
The filter envelope shapes the timbre and overtone content of the audio signal as it flows from the circuitry of the
mixer. This envelope or contour generator is used to dynamically move the cutoff frequency. It works as such: each
time a key is depressed an envelope or contour generator attached to the filter’s cutoff frequency is actuated, and
sends a control signal to the filter. The control signal rises at one rate, falls at a second rate, levels off at a certain
point, and then finally falls off at a third rate. These four parameters and their effect upon the cutoff frequency are
explained below.
The ATTACK knob sets the attack time. The attack time determines the initial segment of the envelope. The frequency
at which the contour begins is determined by the filter frequency setting, while the peak, which it reaches, is
determined by the filter frequency and Envelope 1 amount settings combined. Incrementing the ATTACK knob value
from “0 - 10” will result in the brightness of the sound increasing sharply at first, and then more gradually as the
attack time lengthens. Switching INVERT on reverses the behaviour of the normal ADSR envelope. During the attack
phase (beginning when the key is pressed), the sound fades from the maximum amplitude to zero; during the decay
phase, it rises to the value determined by the sustain setting; after the key has been released, the sound parameter
rises from sustain amplitude back to maximum amplitude: tricky and nice. Switching LOOP on causes the attack and
decay values to repeat or loop, transforming Envelope 1 into a quasi LFO. The sustain parameter is in effect as well.
The DECAY knob sets the decay time. The decay time determines the duration of the second segment of the envelope,
i.e., the fall from the attack peak to the sustain level. When repeatedly depressing a key and incrementing the value
from “0 – 10,” you will at first hear the brightness drop sharply after the initial attack. This drop will become more
gradual as the decay time lengthens.
The SUSTAIN knob sets the sustain level. The sustain level determines the filter frequency at which the envelope
“levels off” after the initial rise and fall. The frequency of the sustain level can be as high as the initial peak, in which
case there is no decay after the initial rise, or it can be as low as the frequency at which the envelope contour began.
The RELEASE knob sets the release time and is the fourth and final stage of the envelope contour. Finally, after the