Switch to advanced view, and set the Release time for AHDSR1 to a suitable length for your release samples.
Switch to one of the sources with the A/B/C/D buttons, then click the Edit button to open the Main edit window.
Click the select field, and choose Import Audio.
Select a sample (or multiple samples) representing the main sustain portion of your sound, and import using any of the available import modes.
Alchemy analyzes each sample to determine the root pitch (if not defined in the filename), set the root key, key range, and velocity range for each sample zone such that they span the entire keyboard and the entire dynamic range, and add all zones to a group named Group 1.
Click the “+” symbol at the top of the Group section, and choose Import.
Select a sample (or multiple samples) representing the release portion of your sound, and import (the import mode is automatically set to match the existing group).
Alchemy again analyzes each sample and adds all zones to a group named Group 2.
Double-click Group 2, then click the Trig field and change it to Release.
Zones in Group 2 will now trigger when you release each key, playing over zones in Group 1 which continue to sound until AHDSR1 reaches the end of the release stage.
Double-click Group 1 in the list, then click the Fade field and change it to a value other than 0.
Zones in Group 1 will now fade out when the note is released, allowing Group 2 to be heard during the release stage of the sound. Higher Fade values result in slower fades.
As an option, double-click Group 2 in the list, then click the Fade field and change it to a value other than 0.
Zones in Group 2 will now fade in when the note is released, creating a crossfade between Groups 1 and 2 at note-off. Higher values result in slower fades. Fading in the release group may be unnecessary if your release samples already have a natural fade in at the start, however, or undesirable if a percussive transient is required at note-off. Try to set Fade values for Group 1 and 2 to an identical small value to create a sudden but click-free crossfade at the end of each note.
In Alchemy in Logic Pro, click the File button in the Name bar and choose Initialize Preset from the pop-up menu to reset all Alchemy parameters to default settings.
Important: Use of Initialize Preset automatically turns on wide unison mode. See PDF
Logic Pro Effects: PDF