This project is an Attack-Decay envelope generator, with no “hold”, as soon as the envelope reaches it’s peak, it immediately begins to decay.
There are three envelope curve options;
Linear, Logarithmic and Exponential.
The output level is controllable, inverted envelopes are specified by a negative gain voltage. All of the timings are in seconds per volt, there is no conversion needed between voltage and time.
This project relies on third party modules.
These modules are available from Elena Novaretti’s website
ED Glider 2,
ED Log (Audio),
ED Clip (Audio).
How the Timing section works.
A trigger pulse is received from the MIDI keyboard, or a suitable trigger source, this only needs to be a short pulse, no matter how long the trigger pulse is the envelope timing will not be affected. The attack control voltage is sent directly to the UP Time (sec) plug on the ED Glider 2 module, and to the Monostable Pulse Length via a Multiply module which has it’s Input 2 set to 10 (Attack V *10) as the timing voltage for the Monostable is in 1/10th Second per volt. This send a pulse with the same timing as the UP Time for the ED Glider 2 module (Without this the attack wouldn’t work for any timing except 0). The Decay control is sent directly to the Down Time (sec) plug.
Note: For the Envelope Generator to produce the correct results when used with a VCA module the VCA must have its response set to linear.
The Envelope Curve section.
Exponential:
This uses a Level Adj module with Input 1 and Input 2 both connected to the output of the Glider module. This means that the output will be Input 1 * Input 2 converting a linear voltage envelope into an exponential curve.
Linear:
Is taken directly from the output of the Glider 2 module through a Level Adj module with its Input 2 set at 10.
Logarithmic:
The Glider 2 output is fed through the ED Log (Audio) module. There is a range Clipper on the output to ensure that the voltage cannot pass outside the normal 10V range (I found that sometimes negative voltages were being produced at the start/end of the envelope), and the Level Adj module to increase the positive output voltage to the normal level.
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