
Retro Synth features two identical attack, decay, sustain, and release (ADSR) envelopes that shape the filter cutoff and the level of the sound over time.
When you think of different sounds, such as a snare drum, piano, or strings, they’re not only tonally different, but the characteristics of the sound change over time. Both the snare drum and piano are heard immediately when struck. This is because they both have a short attack phase. Bowed strings, on the other hand, slowly ramp up in level—they have a long attack time, in other words.
If you break down any sound over time, you can emulate snare drum-like, piano-like, or string-like characteristics easily with Retro Synth envelopes.

Attack handle: Drag horizontally to set the time it takes for the envelope to reach the initial level.
Note: Oscillators automatically switch from free mode to synced mode when the Attack time is set to values below 0.50 ms. This has a pronounced effect on stacked voices, in particular. See global and controller settings.
Decay handle: Drag horizontally to set the time it takes for the envelope to fall to the sustain level, following the initial attack time.
Sustain handle: Drag vertically to set the sustain level, which is held until the key is released.
Release handle: Drag horizontally to set the time it takes for the envelope to fall from the sustain level to a level of zero.
Velocity slider: Determine how sensitive the envelope is to incoming velocity.
If set to maximum, the envelope outputs its maximum level only when the keys are struck at maximum velocity.
Softer velocities result in a corresponding change to the levels of each envelope—with a 50% velocity resulting in half-levels for the attack and sustain level parameters. Envelope attack, decay, and release times are not affected by velocity modulation.