Features
Controls
Connections

Features

Specifications: The XDM400/4 is rated at 75 watts RMS x 4-channels into 4Ω, 100 watts RMS x 4-channels into 2Ω, and 200 watts RMS x 2-channels bridged into 4Ω; all measurements taken at 14.4 volts with no more than 1% THD+N. The Signal to Noise ratio is 104 dB at rated power and 84 dB at 1 watt (both A-weighted).

NexD Class D Technology: NexD is a switching amplifier design that combines exceptional audio quality with excellent efficiency and less complexity. This results in an affordable compact amplifier with exceptional audio quality and total efficiency.

Advanced Rollback Protection: The XDM-Series amplifiers employ advanced thermal and low-impedance protection to virtually eliminate annoying amplifier shut-down events. Should any XDM-Series amplifier overheat, its intelligent, unregulated power supply reacts by limiting available peak voltage until the amplifier returns to a safe temperature range. Likewise, if an impedance lower than optimal for the amplifier is present at the outputs, the XDM amplifier will roll back peak voltage to protect itself without shutting down.

Differential-Balanced Inputs: The amplifier features differential-balanced input architecture to effectively control noise and ensure compatibility with a wide variety of source units, including many OEM systems. Without resorting to line output converters, you can directly connect most OEM source units to the JL Audio amplifier without creating any noise or compatibility issues. Unlike conventional single-ended inputs, the differential-balanced design does not connect one side of the audio signal to chassis ground. This eliminates any voltage sensitivity between one input terminal and ground and greatly reduces the incidence of alternator whine in a typical car audio installation.

Protection Circuitry with Status LED: There is a single multi-color LED on the top panel to indicate the amplifier's operating status.

• Flashing Green: The amplifier is powering up and audio output is muted.
• Constant Green: The amplifier is turned on and operating normally.
• Constant Red: Indicates the amplifier has exceeded its safe operating temperature, putting the amplifier into a self-protection mode which reduces the power output; the LED will return to green and the amplifier will resume normal, full-power operation when the heat sink temperature drops back to a safe level.
• Constant Amber (Yellow): Indicates an over-current condition has occurred, accompanied by a muting of the affected amplifier channels (over-current can be caused by speaker impedance lower than recommended or a short-circuit in the speaker wiring).
• LED Off: The only condition that will shut down an undamaged XDM400/4 completely is the battery voltage or remote turn-on voltage dropping below 10-volts.

Cooling System: The outer shell of the JL Audio amplifier is designed to dissipate heat from the amplifier circuitry. For optimum cooling performance, this outer shell should be exposed to as large a volume of air as possible. Enclosing the amplifier in a small, poorly ventilated chamber can lead to excessive heat build-up and degraded performance.

Controls

Control Panel Cover: The XDM400/4 features a Control Panel Security Cover which protects and hides the amplifier's controls. When installed, the cover ensures that the amplifier's settings are not accidentally changed, while creating a clean aesthetic look for the amplifier and your installation. The cover is installed at the factory and must be temporarily removed for access the amplifier's controls. The security cover is secured by two 2.5mm Allen-head machine screws.

Gain Setting: Using JL Audio's guided gain set up requires a digital AC voltmeter and a test CD (both sold separately) with a sine-wave test-tone recorded at 0 dB reference level in the frequency range to be amplified for that set of channels (approximately 50 Hz for subwoofer channels). The gain can also be set by ear with no additional equipment. Two gain adjustment dials are provided, one for channels 1&2 and one for channels 3&4.

Input Filter: This 2-way switch can help eliminate electrical interference:

• Car: This setting will be commonly used for most automotive or marine installations.
• Boat: Select this setting if experiencing interference from high-current mechanical switches or devices (more common in marine craft).

Turn-On Mode: There are three options for turning the amp on, selected using the Turn-On Mode switch:

• Remote: The amp turns on when +12 volts is applied to the remote terminal.
• Offset: The amp turns on when a DC offset is detected on the channel 1 inputs (from a speaker level source).
• Signal: The amp turns on when a full-range audio signal is detected on the channel 1 input (from a speaker level source).

Preout Signals: A 2-way selector switch lets you choose which input signals will be passed to the pair of RCA preouts:

• 1&2: The preouts pass signals from inputs 1&2.
• Sum: The preouts pass signals from all inputs, with channels 1&3 and 2&4 being summed together.

Remote Level Mode: If connecting an optional HD-RLC remote level control (sold separately) , this 2-way switch deterimines which channels will be affected by it. Options include:

• All: The remote level control will increase/decrease the level of all channels.
• 3&4: The remote level control will increase/decrease the level of channels 3&4.

Input Mode: 2-Way switch:

• 2 Ch: Select this if only using RCA inputs 1&2. The stereo signals on inputs 1&2 will also be passed to channels 3&4.
• 4 Ch: Select this when using all four RCA inputs.

Crossover (x2): The filter type and crossover point for channels 1&2 and 3&4 are independently adjustable:

• Filter Mode: Three-position switch:
  • Off: The crossover is bypassed; assuming a full range signal is input, the output will be the full range.
  • HP: Sets the crossover to high-pass; slope is 12 dB/octave.
  • LP: Sets the crossover to low-pass; slope is 12 dB/octave.
• Filter Frequency: A rotary control sets the crossover point from 50 to 500 Hz.

Connections

Power/Ground/Turn-On Terminals: The amplifier features set-screw terminals for the power, ground, and remote turn-on connections.

• Power and Ground: Accepts 4 AWG wire (recommended); a A 2.5mm Allen wrench is supplied for making connections
• Remote Turn-On: Accepts 18 to 12 AWG wire; the same 2.5mm Allen wrench is used for making the connection

Speaker Output Terminals: The XDM400/4 features four output channels. If making a bridged connection, only the Left + and Right - terminals are used for that pair. The set-screw terminals will accept 16 to 8 AWG speaker wire. The included 2.5mm Allen wrench is used for making connections.

Preamp Inputs: The amplifier has two pairs of differential-balanced stereo RCA jack inputs. In addition to preamp level signals, the RCA inputs can also be used with speaker level signals (136XDCLR2S required and sold separately).

Preamp Outputs: The XDM400/4 incorporates a pass-through preamp output section, so that an additional amplifier can easily be connected to the same signal feeding the input. This preamp output signal is buffered to prevent noise and is always preamp level, regardless of the signal level feeding the input. The preamp output is not affected by the XDM400/4's internal crossover. Preamp output signals can be selected using the Preout switch (1&2 and Sum).

Remote Level Control: The amplifier features an RJ-14 telephone jack for adding an optional wired remote level control. With the addition of the optional wired remote (item number 136HDRLC, sold separately), you can control the output level of the amp from the front of your vehicle. If desired, multiple XDM amplifiers can be controlled from a single HD-RLC controller using a simple phone line splitter and multiple phone cables (all sold separately).