The Sub 37 is capable of tuning itself from the calibration menu. This can be found in the Global menu, in the Calibration submenu. The first option in this submenu is Note Cal. By default, the Start Note is 15 and the End Note is 116. 

This will be fine for most applications. Press the Save button to begin, and the Sub 37 will begin calibrating itself note after note, starting from the lowest.