[. . . ] GT5-A3001 OWNER'S MANUAL 4x 2x 1x 9-1/4" 235mm 12" 305mm 2-1/8" 54mm A B C D A GT5-A3001 CAR AUDIO SUBWOOFER AMPLIFIER OWNER'S MANUAL Installation Warnings and Tips · Disconnect the negative (­) lead from your vehicle's battery. [. . . ] 5 Input-Level Control · Used to match the input level of the amplifier to the output level of the source unit. 6 Protect LED · Illuminated under any of the following fault conditions: battery over/under voltage, short circuit in speaker wires, amplifier is too hot, amplifier's output circuit has failed (DC voltage is present in the amplifier's output). 7 Low-Pass Filter Frequency Control · 12dB/octave low-pass filter, variable from 32Hz to 320Hz. 9 Setting Input Level A Turn Input Level control counterclockwise to 6V (minimim). B With a dynamic music track playing, turn the head unit's volume control to the 3/4 position. C Turn Input Level control clockwise until the bass output is proportionate to the output of the high-frequency speakers, according to your preference. [. . . ] 2, route de Tours 72500 Château du Loir France declare in own responsibility that the product described in this owner's manual is in compliance with technical standards: EN 55013:2001+A1:2003 EN 55020:2002+A1:2003 Klaus Lebherz Harman Consumer Group, Inc. [. . . ]