THE ANALOG FOUR MKI/MKII, AND ANALOG KEYS ENVELOPES
The amplitude envelopes and the assignable envelopes offer 12 different shapes, consisting of six basic shapes each with two different trigging behaviors. The envelope shape graphics indicates how the envelope will affect the modulation destination. The left portion of the graphics shows how the envelope behaves when it is rising, i.e. the attack phase, and to the right the falling behavior is shown, i.e. decay and release. The rise and fall can each be either linear or exponential, useful in different applications as described below. A dot to the left of the visual representation of the envelope indicates that the envelope will restart from level zero each time it is trigged. Envelope shapes without a dot mean the envelope will start from the level it had when being trigged.
0–1 Linear attack and decay/release. An envelope shape suitable for controlling the filters if linear attack/decay/release sweeps are desired. When used as an amplitude envelope the decay and release phase appears to drop quicker towards the end, making it most useful for sounds that should fade out without a tail.
2–3 This can be considered the standard envelope shape. Decay and release fall quicker in the beginning of their phase, behaving more snappy and – just like acoustic sounds tend to do – leaving a tail instead of ending abruptly. This envelope shape is useful for creating distinct sounds, for example, kick drums and basses, but also lengthier sounds like pads.
4–5 Exponential attack, linear decay/release. This shape makes the envelope rise quicker and quicker. This envelope is suitable when for example creating sounds appearing to be played in reverse or for sounds requiring a sudden attack.
6–7 Exponential attack, exponential decay/release. Since our hearing perceives loudness exponentially, this shape is primarily useful as an amplitude envelope for very long sounds that are supposed to fade in and fade out at a very constant rate. When used as a filter envelope, very clicky, whip lash-like sounds can also be obtained by using this shape.
8–9 Full attack, linear decay/release. The envelope will immediately rise to the full envelope level and stay there for the whole attack phase. The ATK parameter sets the duration of this attack phase. The envelope shape is useful as amplitude envelope for certain percussive sounds that need a punch at full volume followed by a quick decay, or for other sounds that should contain a full body before being entering the decay phase.
10–11 Full attack, exponential decay/release. The envelope behaves like shape 8-9 mentioned above, but decay and release will fall in a more snappy fashion, ending with a tail. This makes it even more useful for percussive sounds.