KEY1 Neck pickup input. (H hot input C cold input) 12 Output.2 Gain preset for neck pickup. 13 Ground3 Bridge pickup input. (H hot input C cold input) 14 Ground4 Gain preset for bridge pickup. 15 Passive tone connection.5 Treble filter blend. 16 Treble filter connection.6 Neck pickup filter connection. 17 Selector for high-mid frequency 500Hz Both whiteswitches should be moved to select frequency.7 Low-mid gain preset. 18 Selector for high-mid 800Hz Both white switchesshould be moved to select frequency.8 High-mid gain preset. 19 Selector for low-mid frequency 150 Hz. Both whiteswitches should be moved to select frequency.9 Bridge pickup filter connection. 20 Selector for low-mid frequency 250 Hz. Both whiteswitches should be moved to select frequency.10 + ve 9 or 18 volt. 21 Volume Blend11 + ve 9 or 18 volt. 22 Passive tone connection.The two presets marked with a red X are not user adjustable and should in no circumstances be moved. This will void thewarranty and AC Guitars will not be responsible for any damaged caused to the pre-amp or attached equipment.AC GUITARSBASS-EQ-03 FILTER STYLE ACTIVE PREAMPACG EQ03 4K/A & 5K A/P iNSTruCTiON mANuAL