Set all pot controls to their minimum position except [IN 1 LEVEL] which should be set to it's maximum position Adjust P201 fully anti-clockwise Select [CLEAN] Apply a 200Hz 5VAC triangle to [IN 1] Monitor [OUT] Adjust P201 until you cannot hear the signal. Adjust a further 1/2-turn Set [INITIAL GAIN] to maximum Adjust P301 for an output of 5Vp-p.