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JL Audio XD400/4v2

4-channel car amplifier — 75 watts RMS x 4

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  • JL Audio XD400/4v2

    Front

  • JL Audio XD400/4v2

    Connection panel

  • JL Audio XD400/4v2

    Connection panel

  • JL Audio XD400/4v2

    Control panel uncovered

  • JL Audio XD400/4v2

    Interior layout

  • JL Audio XD400/4v2

  • JL Audio XD400/4v2

  • JL Audio XD400/4v2

  • JL Audio XD400/4v2

  • JL Audio XD400/4v2

  • JL Audio XD400/4v2

  • JL Audio XD400/4v2

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Our take on the JL Audio XD400/4v2

by Buck Pomerantz
JL Audio

My system has plenty of power. Who needs an amp?

You might think you don't need an amp because you have a 400-watt system in your car, or because your new stereo puts out 50 watts a channel. But those are peak wattage ratings, which may boil down to 15 or 20 watts per channel, using the more realistic RMS rating. An amp sends your speakers the power they need to deliver your music with clarity and impact, whether you're using factory speakers or high-performance components. And low-frequency reproduction requires lots of power, so an amp is an absolute must if you're adding a sub to your system.

Power your system

JL Audio XD600/6v2

Compact design applies to internal components too.

JL Audio's XD400/4v2 amp packs a wallop far beyond what you'd expect from something so small. This compact amp plays your music with true fidelity and impressive impact, without straining your car's electrical system, thanks to JL Audio's proprietary NexD™ amplifier technology. A cast alloy heatsink and an advanced cooling system keep this amp at optimal temperature, eliminating thermal shut-downs so your music keeps going strong without interruption.

Versatile amp

The XD400/4v2 can deliver 75 watts RMS each to 4 full-range speakers, or you can bridge the amp to 2-channel mode to send 200 watts each to a pair of subs. You can also run two speakers with the front channels while driving a subwoofer with 200 watts RMS from the rear channels bridged together.

Works with almost any vehicle's system

"Differential-balanced" inputs keep the signals clear of outside noise, and allow you to connect this amp to just about any in-dash stereo, even a factory radio. The speaker-level inputs feature two auto turn-on modes so you can readily incorporate this amp into a factory system — no need for RCA connections or a remote turn-on lead. An optional wired remote lets you tweak the volume of the whole system from your front seat, or you can switch to the rear channels only, which is handy if you're using them to drive a sub.

JL Audio XD600/6v2

                                           XD600/6v2 connection panel

See more info on this item

Highlights:

  • 4-channel car amplifier
  • 75 watts RMS x 4 at 4 ohms (100 watts RMS x 4 at 2 ohms)
  • 200 watts RMS x 2 bridged at 4 ohms (4-ohm stable bridged)
  • variable low- and high-pass filters (50-500 Hz, 12 dB/octave)
  • optional wired remote controls sub or system level
  • Class D amplifier design with NextD™ switching amp technology
  • differential-balanced inputs eliminate noise coming from your vehicle's electrical system
  • Advanced Rollback Protection System prevents thermal shut-down
Connection Features
  • preamp and speaker-level inputs (speaker wire to RCA adapter required for speaker-level input)
  • high-level inputs — up to 8 volts RMS (about 16 watts)
  • DC offset or signal sensing auto turn-on eliminates need for remote lead
  • preamp outputs
  • 8-gauge power and ground leads and a 40-amp fuse recommended — wiring and hardware not included with amplifier
  • no onboard fuses — when installing multiple amps in a system, an additional 40-amp in-line fuse between the distribution block and the amplifier is recommended
  • 8-9/16"W x 2-1/16"H x 7-1/8"D
  • warranty: 2 years
  • Our 60-day money-back guarantee

Hands-on research from the Crutchfield Labs (what are the Labs?)

Features and Specs
Performance
RMS Power Output (Watts x Channels)
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75 x 4
Peak Power Output (Watts x Channels)
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N/A
Power at 2 Ohms (Watts x Channels)
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100 x 4
Bridged Power (Watts x Channels)
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200 x 2
Minimum Impedance Bridged
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4
Minimum Impedance Unbridged
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2
Best Frequency Response
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12-22000 Hz
THD at Rated RMS Power
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1%
Signal to Noise Ratio
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84 dB
Input Voltage
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14.4v
Features
Amplifier Class
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D
Low-Pass Crossover Frequency
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50-500 Hz
Low-Pass Slope (dB/octave)
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12 dB/octave
High-Pass Crossover Frequency
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50-500 Hz
High-Pass Slope (dB/octave)
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12 dB/octave
Bass Boost
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No
Bass Boost Frequency
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N/A
Fan Cooled
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No
Fuse Rating
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40
Speaker Level Inputs
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RCA
Preamp Outputs
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1 pair
Width (inches)
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8-9/16
Height (inches)
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2-1/16
Depth (inches)
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7-1/8
Parts Warranty
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2 Years
Labor Warranty
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2 Years
Product Research
What's in the box?

Download owner's manual

  • Four-channel amplifier
  • 2.5mm Allen wrench
  • Self-adhesive JL Audio badge
  • Owner's manual

Our Product Research Team

At Crutchfield, you'll get detailed, accurate information that's hard to find elsewhere. That's because we have our own in-house Product Research team — they open the box, verify contents, check the owner's manual, and record dimensions, features and specs. We stay on top of new products and technologies to help people make informed choices.

Features
Controls
Connections

Features

XDv2 Series: The JL Audio XDv2 amplifiers feature big audio performance from a small footprint. With advanced NexD switching technologies, the XDv2 amps exceed 80% efficiency, running cooler than most other amplifiers. The Advanced Thermal Rollback System gives you increased reliability and better audio performance by virtually eliminating thermal shut-down. Because the XDv2 amps employ smaller cast alloy heat sinks, they can be installed in smaller spaces. XDv2 amplifiers feature a black powder-coat finish with a brushed aluminum cover for the controls.

Four-channel Class-D Amplifier: The XD400/4v2 is a Class-D 4-channel amplifier, designed specifically for full-range operation, but can be used to power subwoofers. The amplifier is stable down to 2 ohms in stereo, or bridged to a 4 ohm load.

Amplifier Rating: The XD400/4v2 is rated at 75 Watts RMS x 4 channels at 4-ohms (20 Hz to 20 kHz), Signal-to-Noise Ratio of >104 dB (at rated power), 1% THD, @14.4 Volts. At 2 ohms, the rated power is 100 Watts RMS x 4, and bridged at 4 ohms, it outputs 200 Watts RMS x 2.

Advanced Rollback Protection: The XDv2-Series amplifiers employ advanced thermal and low-impedance protection to virtually eliminate annoying amplifier shut-down events. Should any XDv2-Series amplifier ever 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 XDv2 amplifier will roll back peak voltage to protect itself without shutting down.

Differential-Balanced Inputs: The XD400/4v2 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 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.

Note: You will need a Speaker Wire to RCA adapter (sold separately) for each pair of channels to connect this amplifier to your head unit via speaker level.

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

  • Flashing Green: When the LED is flashing green, the amplifier is powering up and audio output is muted.
  • Constant Green: This LED lights green to indicate that the amplifier is turned on and operating normally.
  • Constant Red: This Red LED lights to indicate that the amplifier has exceeded its safe operating temperature, putting the amplifier into a self-protection mode, which reduces the power output of the amplifier. The red light will shut off and the amplifier will return to normal, full-power operating mode if the heat sink temperature drops back to a safe level.
  • Constant Amber (Yellow): The Amber (Yellow) LED light indicates that an over-current condition has occurred and is accompanied by a muting of the amplifier's output. Over-current condition can be caused by a speaker impedance lower than the optimum load impedance range for the amplifier or a short-circuit in the speaker wiring.
  • LED Off: The only condition that will shut down an undamaged XD400/4v2 completely is if battery voltage or remote turn-on voltage drops below 10 Volts. The amplifier will turn back on when voltage climbs back above 11 Volts.

Cooling System: The outer shell of the JL Audio amplifier is designed to remove 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 XD400/4v2 features a brushed aluminum 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 control panel security cover is pre-installed at the factory and must be temporarily removed to access the amplifier's controls. The security cover is secured by two 2.5mm hex-head screws.

Simplified Gain Setting: This XDv2 Series amplifier makes setting the gain level of the amp via the input sensitivity control very simple. All you need is Digital AC Voltmeter and a CD Test Disc with a sine-wave test-tone recorded at 0 dB reference level in the frequency range to be amplified for that set of channels (50 Hz for subwoofers, 1 kHz for a midrange application). Each pair of channels has a separate Input Sensitivity control.

Flexible Input Section And Active Crossover Network: The XD400/4v2 amplifier provides a flexible input section and a comprehensive crossover network to fine tune your system effectively and accurately. This 4-channel amplifier is divided into two separate pairs of channels, each with their own crossover:

  • Filter: The front and rear channels are equipped with a 12 dB/octave Butterworth filter which can be configured as a low-pass (LP) or high-pass (HP) filter, or defeated (OFF). You can set the Filter Mode via a three-way switch.
  • Filter Frequency: The filter frequency can be selected using the rotary control. The control has forty detented positions for selecting the precise frequency you desire. There are markings at 50Hz, 60Hz, 80Hz, 120Hz, 200Hz, and 500Hz, plus there is a chart in the Owner's Manual with the exact cutoff frequency for each detent. You'll need a small screwdriver (not included) to set the frequency.

Turn-on Options: The Turn-on Mode Switch lets you choose the method for turning the amplifier on and off:

  • +12V Remote Turn-on Lead: The preferred method for turning the amplifier on and off is by running a turn-on lead from the source unit and connecting it to the Remote terminal. When +12V is present at the terminal, the amplifier will turn on. When the +12V is turned off, the amplifier will shut off. The set screw connector on the Remote terminal will accept 18 AWG to 12 AWG wire.
  • DC Offset-Sensing: The amplifier will turn on and off when the presence of a very small DC signal (or offset) is detected on the amp's RCA left channel input. The amplifier will turn off when this DC Offset is no longer present. This method is designed for high-level (speaker-level) input signals, not for low-level (line-level) signals.
  • Signal-Sensing: The amplifier will turn on and off by detecting the presence of a full-range audio signal at the left-channel input. The amp will turn off approximately 30 seconds after the audio signal is no longer detected. This method is designed for use with high-level (speaker-level) input signals and not for low-level (preamp level) signals.
Note: When the DC Offset or Signal Sensing turn-on methods are being used, the amp's Remote terminal can be used as a remote turn-on output for other amplifiers or accessories in the system.

Additional Controls: In addition to the Input Sensitivity, Filter Mode/Frequency, and Turn-on Mode controls, the XD400/4v2 has the following controls under the control panel:

  • Preouts From: The pass-through preamp outputs can be configured two different ways:
    • 1&2: The preamp output delivers the same signal that is connected to the CH 1&2 inputs. This allows channels 3&4 to be faded without affecting the subwoofer level. If CH 1&2 is faded in this mode, the signal level of the preamp output will change accordingly.
    • Sum: The preamp output will deliver a summed Front/Rear stereo signal to a subwoofer amplifier, while permitting fading from the front to rear speaker systems from the source unit. No loss of signal occurs to the subwoofer amplifier when the system is faded to the front or rear by the head unit.
  • Remote Level Mode: You can assign the operation of the connected HD-RLC to one or both pairs of channels. This two-way switch lets you select ALL or 3&4.
  • Input Mode: The Input Mode switch lets you send four discrete channels into the amplifier, or use only two channels to feed all four amplifier channels. You can set the Input Mode to 4 CH or 2 CH.

Connections

Power/Ground/Turn-On Terminals: This JL Audio XDv2 amplifier features set screw clamp terminals for the power, ground, and remote turn-on connections. A 2.5mm hex-wrench is supplied for tightening or loosening the set screws.

  • Power and Ground: The amplifier's set screw clamp Power and Ground connections are designed to accept up to 4 AWG power wire. JL Audio recommends 8 AWG power and ground wire for this amp.
  • Remote Turn-On: The amplifier's set screw clamp turn-on lead will accept 18 to 12 AWG wire.
Note: The Amplifier is not equipped with a fuse. An external 40-amp AFS, AGU, or MAXI fuse must be installed on the power wire. If a wiring kit is used which includes a fuse with a value other than 40 amps, the original should be replaced with a 40-amp fuse.

Speaker Output Terminals: The JL Audio XD400/4v2 features four set screw clamp speaker terminals for an easy stereo connection. You can also bridge the amplifier by connecting a 4 ohm load to the CH1/CH3 positive and CH2/CH4 negative terminals. The terminals will accept 16 to 8 AWG speaker wire.

Preamp Inputs: The amplifier features two sets of differential-balanced RCA jack inputs with an Input Voltage switch. For preamp level signals, the switch should be set to LOW. For speaker level signals, the switch should be set to HIGH. The rotary Input Sensitivity gain control can be set the amp to the specific signal source that is feeding it. The amplifier's input voltage range is 200mV-2V (LOW) and 800mV-8V (HIGH).

Preamp Outputs: The XD400/4v2 incorporates a buffered pass-through preamp output section, so that additional amplifiers can be easily added to the system. The preamp output signal is not affected by the amp's Low-Pass Filter. If the Input Voltage switch is in the LOW position, the level of the Preouts matches the input signal strength. When the Input Voltage switch is in the HIGH position, the level of the input signal is attenuated -12dB to produce a line-level signal at the Preouts. You can select which channels feed the preamp outputs: 1&2 or Summed.

Remote Level Control: The amplifier features a standard RJ-14 telephone connector for adding the optional wired HD-RLC Remote Level Control (sold separately). The Remote Level Control lets you control the volume of the XD400/4v2 from the driver's seat.

 
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JL Audio XD400/4v2 Reviews

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5 out of 5

Amazing amp

Written By Anonymous, Upland, ca on Sunday, May 25, 2014
 
It is an amazing amp for it's size. I used it to power my sub and two tail gate speakers for tail gating and is perfect.
Pros:
Size vs power ratio
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For a more in-depth review and enhanced detailed information on the JL Audio XD400/4v2, please visit the Crutchfield website product page (/ISEO-rccbcspd/p_13698602/JL-Audio-XD400-4v2.html ).