Introduction
An .exs file is an instrument for EXS24, the sampler built into
Logic Pro. EXS24 was replaced by the
Sampler instrument in Logic Pro 10.5, which still opens .exs files, so
many sample libraries for the Mac continue to ship in this format.
Structure
An EXS instrument is a binary file that maps samples to the keyboard. It holds zones, each pointing to one sample file with its key range, velocity range, root key, tuning and loop settings, and groups that collect zones and set shared playback options. The samples are not inside the file: they are WAV or AIFF files referred to by name and path, which Logic searches for when the instrument loads. Apple does not publish the format.