Calibrate Aftertouch

1. Enter the Calibration menu (Edit -> X1 -> CAL -> Enter).
2. Select CCM and press Enter.
3. Press and hold the key(s) with maximum force to be used for Aftertouch.
4. While holding the key(s) with minimum force to trigger Aftertouch, press the Snap Shot button (display should show 'tHr').
5. Press Enter to store.
6. Press Home to finish.

Source: Xboard 25 — emu-xboard-25-49-61-manual-eng (manual)