[. . . ] Be sure to protect all cables and important equipment such as fuel lines, brake lines and the electrical wiring from damage. If the output is low, even when the volume of the car stereo is turned up, turn these controls clockwise. If there is distortion when the volume of the car stereo is turned up, turn these controls counter-clockwise. [. . . ] If they do not conform, they may catch fire, emit smoke or become damaged. But in case of two-channel and other bridge connections, the speaker impedance must be 2 to 8 ohms. Install and route the separately sold battery wire as far away as possible from the speaker wires. Install and route the separately sold battery wire, ground wire, speaker wires and the amplifier as far away as possible from the antenna, antenna cable and tuner. Cords for this product and those for other products may be different colors even if they have the same function. When connecting this product to another product, refer to the supplied Installation manuals of both products and connect cords that have the same function. Subwoofer Other than subwoofer Subwoofer Other than subwoofer Subwoofer Other than subwoofer Subwoofer Other than subwoofer After making all other connections at the amplifier, connect the battery wire terminal of the amplifier to the positive (+) terminal of the battery. External Output If only one input plug is used, do not connect anything to RCA input jack B. The female terminal can be connected to the auto-antenna relay control terminal. If the car stereo does not have a system remote control terminal, connect the male terminal to the power terminal through the ignition switch. Always use the special red battery and ground wire [RD-223], which is sold separately. Pass the battery wire from the engine compartment to the interior of the vehicle. After making all other connections to the amplifier, connect the battery wire terminal of the amplifier to the positive (+) terminal of the battery. Expose the end of the speaker wires by about 10 mm and twist using nippers or a cutter. You must attach the supplied terminal cover to the speaker output terminal. Connect the speaker leads to suit the mode according to the figures shown below. [. . . ] After installing the amplifier, confirm that the spare tire, jack and tools can be easily removed. Cut off frequency: 40 -- 120 Hz Cut off slope: ­12 dB/oct High pass filter . Cut off frequency: 40 -- 120 Hz Cut off slope: ­12 dB/oct Maximum input level/impedance . [. . . ]