For precise filter frequency information refer to Appendix B (page 15). Multi-Amplifier SYSTEMS Using the “Preamp Outputs” of the XD400/4, it is easy to configure many different multi-amplifier systems. The most common type involves the addition of a subwoofer amplifier, such as the XD600/1. Common configurations of such a system are described below. Bi-Amplified System with one XD400/4 in four-channel mode and a separate subwoofer amplifier This configuration requires that the separate subwoofe

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

If the channel pair is operating in stereo, it is only necessary to measure one channel. If bridged, make sure you test the voltage at the correct connectors (L+ and R–). 8) Increase the “Input Sens.” control until the target voltage is observed with the voltmeter. 9) Once you have adjusted the XD600/6 to its maximum low-distortion output level, reconnect the speaker(s). The “Input Sens.” controls can now be adjusted downward if the amplifier requires attenuation to achieve the desired system ba

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

4. Connect the REMOTE terminal to an external switch for positive 12V turnon-off. This may be connected to the head unit power antenna lead. Installation Precautions This amplifier comes complete with all mounting harware required. Please remember that this is a high-power unit, which generates considerable electrical energy and heat. Therefore, be sure to install the unit in a place with sufficient airflow, a minimum of dust, and no moisture. Allow enough space around the cooling fins to permit

If hiss/noise disappears, go on until the faulty/noisy component is found. • It is best to set the amplifier's input level as insensitive as possible. The best subjective S/N ratio is obtainable this way. Try to drive as high a signal level from the head unit as possible. Protection LED comes on when the amplifier ispowered up. • Check for shorts on speaker leads. • Check that the volume control on the head unit is turned down low. • Remove speaker leads, and reset the amplifier. If the Protecti

Should this occur, the PROTECT LED will be illuminated. At that time, it is important that you check to determine what has caused the protection circuitry to become activated. If the amp shut off because of a thermal overload, allow it to cool down before attempting to restart. If the shutdown occured because of an input overload, or speaker short circuit, be sure to correct these conditions before attempting to restart the amp. To reset the amp, turn the REMOTE power off and on again. Power LED

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 + - -

• Gold Plated Terminals for Speaker Output and Power Input. • Thermal, Overload and Short Protection• Variable Sub-sonic Filter (15Hz~40Hz, 24dB/Octave) • Variable Low-pass Filter (20Hz~250Hz, 24dB/Octave) 5 13 2 874 6 +18db0BASSBOOST 35 400 HzLPF HPF 80 2.5k Hz LEVELMIN MAX FULL HPFLPFFREQ. GROUND +12V BATT REM FUSEL RBRIDGED+ - - + - + SpecificationsOUTPUT POWERRMS @ 4 OHMSRMS @ 2 OHMSMAX OUTPUTBRIDGE MODEFREQUENCY RESPONSEINPUT IMPEDANCELOW LEVEL INPUTSHIGH LEVEL INPUTSINPUT SENSITIVITYLOW LE

Your amplifier has been designed and manufactured to exacting standards in order to ensure years of musical enjoyment in your vehicle. 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 fa