The Amplifier Envelope section consists of a standard attack, decay, sustain, release-style (ADSR) envelope generator controlling voltage-controlled amplifers (VCA's) for each voice.

A simple analogy would be to think of the voltage controlled amplifier (VCA) as a faucet that gets adjusted by an incoming control voltage from an envelope generator, low-frequency oscillator, or other modulation source that controls the volume of each individual note.

Elka X's under-the-hood VCA section doesn't have any dedicated controls per se, but it has a dedicated envelope generator for shaping amplitude curves.

How An ADSR Envelope Generator Works

When Elka-X sees a gate voltage from a note, the envelope generator outputs a dynamically changing voltage, according to the settings of its four stages. The attack stage defines how long it takes for the output voltage to rise from zero to full scale. Once the attack stage reaches its max amount, it moves to the decay phase, which defines how long it takes to fall from full scale to the setting of the sustain phase. Unlike the attack, decay, and release phases, which define times, sustain simply sets the held voltage level following the attack and decay phases - this equates to the envelope output level while holding down a key. Finally, the release slider defines the the length of time it takes for the voltage to fall back to zero when the gate input voltage is removed, i.e. when the key is released.


Attack- Defines the length of time for amplitude to rise from zero to full scale when a key is played.

Decay- Defines the length of time for amplitude to fall from the attack stage peak to sustain stage setting.

Sustain- Sets the amplitude level following attack and decay phases while a note is held.

Release- Defines the length of time for amplitude to fall from sustain level to zero when a key is released.

Velocity- Defines how much the envelope affects note amplitude via keyboard velocity. When set to zero, keyboard velocity has no effect on cutoff frequency; all the way up results in maximum control range.

Continue to Keyboard section