ENV1 – Attack Decay
Rev1 – June09
Overview
The ENV1 is a voltage-controlled Envelope Generator offering
Attack (Sustain) Decay type events plus a looping oscillator
mode.
The module uses Vactrols to control the speed of operation.
Controls
1.
Range Switch –
3 position switch to select envelope
speed.
- Fast (Up) is designed primarily for audio-rate
oscillation in loop mode.
- Mid provides typical control envelope speeds and
mid-range oscillations from LFO to low audio range.
-Slow (Down) offers an overall slower response for low
modulation rates.
2.
Attack CV Modulation Input –
typical 10V peak to
peak modulation signal.
3.
Status LED
4.
Decay CV Modulation Input –
typical 10V peak to
peak modulation signal.
5.
Gate Input –
a 0 – 5v gate signal is typically applied
here to trigger the envelope.
The input is protected against negative voltages and
can accept higher input signals too. This allows, for
example, a VCO waveform centred around 0V to be
applied – by using the A/S/D mode in Fast range tonal
divisions can be achieved. Other external signals can
be used to varying effect.
6.
Attack Rate Control
– Manual control for envelope
Attack. Note that clockwise corresponds to a rising
frequency (ie. Shorter time). At low settings the
control may take a short moment to stabilize due to
the nature of the Vactrol control elements.
7.
Attack Modulation Control
– a bipolar modulation depth control to modify the envelope Attack rate.
Audio-rate modulation can be applied, but may not always produce a strong effect due to the nature of
the Vatrols.
8.
Decay Rate Control
– Manual control for envelope Decay – similar to Attack.
9.
Decay Modulation Control
– a bipolar modulation depth control to modify the envelope Decay rate –
similar to Attack.
10.
Mode Switch
– 3 way switch to select the mode of operation (see diagram overleaf)
- A/S/D (Gated): An Attack stage is initiated by a Gate signal. Once the peak is reached, this level is
sustained until the Gate signal is released, at which point the Decay stage occurs (Fig.1). If the Gate
signal finishes before the Attack stage has completed then the Attack stage will still continue to peak
with the Decay stage occuring immediately afterwards (similar to A/D mode)
- A / D (Triggered): The positive going edge of a Gate signal begins the Attack stage. The output rises to
peak 10V before entering the Decay stage (Fig.2). The length of Gate has no effect in this mode.
- Loop: In this mode the envelope continually cycles between Attack and Decay. A Gate signal may still
be applied to reset the envelope in loop mode, but the behaviour is somewhat unpredictable as it
depends on the envelope's current status.
11.
Envelope Output –
typical 0 – 10V output signal. Note that the envelope has a roughly exponential
shape.
Specifications
Current Draw: +ve 35mA, -ve 35mA (max.)
Module Width: 1 Frac-width (1.5”)
