Apple Logic Pro 9 - Manual (Page 134)

2 Click the Chase tab, then select the checkboxes of all events that the Chase Events function
should look for before the playback start point.
See Chase Settings for full details.
There is a potential problem when chasing notes that are used to trigger a drum loop in
a sampler. Unless you are lucky enough to start the MIDI region precisely at the beginning
of the sample loop, the sample will be triggered at the wrong time and will play out of
sync with other regions (at least until the next trigger note).
The problem occurs because most samplers can only play samples from the beginning,
and cannot synchronize them to the beat when started in the middle.
To avoid triggering a sampler’s drum loops when chasing note events
1 Activate the No Transpose parameter of your drum loop instrument, in the Track Parameter
box of the Inspector.
2 Turn off the In ‘No Transpose’ Instrument Channel Strips option in the Project Settings >
MIDI > Chase pane.
These settings prevent your sampler’s drum loops from playing until they reach the next
trigger note, whenever the project jumps to a new position.
134 Chapter 5 Navigating Your Project