Some general guidelines for speed regulation expectations when using 590+ DC drives.
If using basic Armature Feedback mode the speed regulation may be as good as 2-4% depending on the implementation, age of the motor/brushes, and external disturbances to the load.
If using Tachometer Feedback mode the speed regulation may be as good as 0.5% largely dependent on the quality of the tachometer as well as the overall application (aka - external disturbances to the load).
Note - these values assume you are not running in the discontinuous region (slow) of the motor.
glh May 2021