When bridged, each channel produces signals of equal magnitude, but opposite polarity. The combined output of the two channels provides twice the output voltage available from a single channel. The XD400/4 has been designed for bridging of its channel pairs without the need for input inversion adaptors. To bridge a pair of channels, use the “Left +” and “Right –” speaker connectors only (the “Left –” and “Right +” remain unused). When bridged, each channel will deliver optimum power into a 4 ohm

Your amplifier has been designed and manufactured to exacting standards in order to ensure years of musical enjoyment in your vessel. For maximum performance, we highly recommend that you have your new amplifier installed by an authorized JL Audio dealer. Your authorized dealer has the training, expertise and installation equipment to ensure optimum performance from this product. Should you decide to install the amplifier yourself, please take the time to read this manual thoroughly so as to fam

“My amplifier doesn’t turn on” Check the fuse, not just visually, but with a continuity meter. It is possible for a fuse to have poor internal connections that cannot be found by visual inspection. It is best to take the fuse out of the holder for testing. If no problem is found with the fuse, inspect the fuse-holder. Check the integrity of the connections made to each of the “+12VDC”, “Ground”, and “Remote” terminals. Ensure that no wire insulation is pinched by the terminal set screw and that

Depending on the subwoofer system and the vessel, different slopes may be required to produce a smooth transition to the mid-bass speakers in the system. Experiment to find the slope which best matches the acoustic requirements of your system. 3) Precise Frequency Selection: The filter frequency markings on the front panel of the amplifier are for reference purposes and are generally accurate to within 1/3 octave or better. If you would like to select the filter frequency with a higher level of

If distortion is present, reduce thesetting of this control. 4 Power Supply Terminals3 Protects the amplifier as well as the automobile electricalsystem from short circuit conditions. Fuse2 These terminals are 14K Gold plated for high conductivityand minimum impedance loss. The terminals faceupwards for easy wiring in tight situations. Speaker Terminals112 Plug in the Remote Bass Boost Control wire in here. 13 Remote Bass Boost REMOTE BASS BOOST CH2 CH1 LOW IN CH4 CH3 LOW IN HI IN CH4 CH3 + - -

This is useful for connection of component speakers or coaxials to this channel pair in a bi-amplified system. “x10” (High-Pass): Configures the filter to attenuate frequencies below a frequency TEN TIMES HIGHER than the indicated filter frequency at a rate of 12dB per octave. This is useful for connection of tweeters to this channel pair in a tri-amplified system. Channel 3 & 4 Filter: 12dB/octave High-Pass or Bandpass Filter “Off”: Defeats the filter completely, allowing the full range of freq