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JL Audio M400/4

4-channel marine amplifier — 75 watts RMS x 4

Item # 136M4004

The M400/4 is small — less than 9" wide — but it delivers a massive amount of power from its...

The M400/4 is small — less than 9" wide — but it delivers a massive amount of power from its...

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Item # 136M4004

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Expected: 9/27/2019

$519.99
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About the JL Audio M400/4

Small footprint, big kick

The M400/4 is small — less than 9" wide — but it delivers a massive amount of power from its compact chassis — up to 100 watts from each of its four channels. It owes these impressive specs to JL Audio's Class D NexD™ ultra-high-speed switching design, which eliminates the traditional drawbacks of a Class D amp design to deliver full-bandwidth performance, excellent efficiency, and very low distortion levels.
JL Audio Built In USA

Small footprint, big kick

The M400/4 is small — less than 9" wide — but it delivers a massive amount of power from its compact chassis — up to 100 watts from each of its four channels. It owes these impressive specs to JL Audio's Class D NexD™ ultra-high-speed switching design, which eliminates the traditional drawbacks of a Class D amp design to deliver full-bandwidth performance, excellent efficiency, and very low distortion levels.

Great for a variety of applications

You can use this 4-channel amp for a variety of applications. Run two sets of high-performance coaxial or component speakers, or bridge the amp to 2-channel mode to get a couple of subs thumping. Or enjoy the best of both worlds by going 3-channel, and powering a sub plus your full-range speakers.

You can run the built-in variable frequency filters in high- or low-pass mode, depending on whether you're powering speakers or subs. JL Audio's optional wired remote lets you adjust the amp's level from the helm, while the preamp outputs make it easier to get signal to another amplifier in your system.

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Product highlights:

  • 4-channel marine amplifier
  • 75 watts RMS x 4 at 4 ohms (100 watts RMS x 4 at 2 ohms)
  • 200 watts RMS x 2 in bridged mode (4-ohm stable in bridged mode)
  • Class-D design
  • white and gray powder-coat finishes, gasketed control cover, and stainless steel hardware
  • variable high- and low-pass filters (50-500 Hz, 12 dB per octave)
  • optional remote level control
  • preamp-level inputs
  • preamp outputs
  • 4-gauge power and ground leads recommended — wiring and hardware not included with amplifier
  • 8-1/2"W x 2-1/16"H x 7-1/8"D
  • warranty: 2 years
  • Our 60-day money-back guarantee
  • MFR # 98271

What's in the box:

  • 4-Channel Class-D marine amplifier
  • 2.5mm Allen wrench
  • JL Audio emblem
  • Owner's Manual

Customer reviews

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JL Audio M400/4 reviews

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JL Audio M400/4

Crutchfield customer from Signal Mountain, TN on 8/12/2019

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Great unit. Very impressed with the sound quality and build quality.

Pros:

Cons:

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JL Audio M400/4

Crutchfield customer from Angleton, TX on 7/13/2019

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Just installed this along with 4 of their speakers. Loved the way you tuned the amp to the head unit

Pros: Quality product excellent sound

Cons: None

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JL Audio M400/4

Crutchfield customer from Summerville, SC on 4/29/2019

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This amp is awesome! I hooked up to JL 8.8's with this amp and it's sounds great and clear!

Pros:

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0 of 0 found this helpful

JL Audio Marine Amps are the best in the business!!!

Brian from Murfreesboro, TN on 4/8/2019

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Let me first off and say that Crutchfield is awesome!. I originally bought 2, Fusion marine amplifiers for my set-up. When I got them in the mail, I realized they were way more powerful than my Fusion 6" speakers could handle. Talked with Crutchfield and explained my situation and requirements. No problem, they emailed me a return label within minutes and by the end of the day, they went ahead and sent me 2 of these amps. Customer service is outstanding!!! I installed these amps. Each amp is powering 4 Fusion MS-FR6022 speakers. I will tell you the sound quality is amazing. These amps push my speakers nice and loud, with no distortion. I blasted my music for hours and still had plenty of battery left over. Prior to my system redo, I had 2 Rockford Fosgate M400-4D (which I did not buy from here) and they were garbage. Within months, both of them started to have channels go out. Sound quality diminished. I cannot even begin to tell you the difference between Rockford Fosgate and JL Audio. Yes, you will pay for the Jl Audios, but save yourself a ton of problems and headaches in the future. I have no doubt that if I have any problem with these amps, between Crutchfield and JL Audio, it will be taken care of. Thank you again

Pros: Everything

Cons: Nothing

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Great Product...DUH ITS JL!

Andrew from Lexington, SC on 9/1/2018

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Big things definitely come in small packages when it comes to this M400/4. I'm powering 4 JL M7.7's on my side by side and this amp rocks those speakers and has handled att the abuse of the trails and mud. I will most definitely be purchasing another in the future for the wife's rig.

Pros: Love the compact size of this amp. Great power and easily adjustable.

Cons: I wish it had the pig tail like it little brother the M280/4

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Can't be Topped for Marine Application

John from Orange, CT on 8/31/2018

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Clearest Amp I have ever owned! I have never skimped on my amps but this Marine amp is the best I have ever heard teamed with JL speakers, Blows my old Wetsounds system away.

Pros: Huge output at a low voltage input. Construction Quality is great, very impressive. Plainly explained, well illustrated directions.

Cons: You get what you pay for, do it one cry once and enjoy the best for life!

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JL Audio M400/4

Michael from Ste Genevieve, MO on 5/30/2018

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Very powerful and compact. Easy to install! I replaced my old M4300's with 2 new technology M400/4's

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0 of 1 found this helpful

Plenty of power

Brad from Canyon Lake, TX on 5/27/2018

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JL quality. Compact and performs well. Paired with M700/5 with remote bass control. Marine rating definitely needed for the boat. Powering 4 tower speakers bridges off the M400/4. Have to turn down the gain, they are so loud!

Pros: Compact and quality

Cons:

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0 of 1 found this helpful

JL Audio M400/4

Crutchfield customer from Wimberley, TX on 5/21/2018

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Nice Amp sounds good, best of all has a small footprint for boat mounting

Pros: Small size,with plenty of power

Cons: Not waterproof

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0 of 1 found this helpful

JL Audio M400/4

Les C from Prior Lake, MN on 5/20/2018

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Small, compact, powerful, good design

Pros: Small and compact but still has all the power you need

Cons: None

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0 of 1 found this helpful

Great sound through all volume ranges

Doug from Petaluma, CA on 4/12/2018

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I bought the JL Audio M400/4 amp for my 2017 Harley Davidson Road king with a full fairing, I replaced a Rockford Fosgate PBR300/4Amp that was clipping and I was not happy with it's performance. Memo a sales associate with Crutchfield recommended it to me. I rewired the complete radio system with my new amp, It performs beautifully at all volume ranges. It is truly worth the time and money to use this amp. If you want a great sound I highly recommend this for your Harley.

Pros: Outstanding performance clean installation WOW!

Cons: None!

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1 of 2 found this helpful

Powerful little amp.

Bill from Chambersburg, PA on 7/9/2017

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This a smokin little amp ! Incredibly small yet powerful, very flexible in the way amp can be set up. Clean detailed music when matched to quality speakers like JL MX series marine. Amp seems expensive but worth the price in terms of quality and music reproduction.

Pros: Sound quality and flexibility.

Cons: None

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0 of 1 found this helpful

JL Audio M400/4

Stephen from Taylorsville, NC on 7/5/2017

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Only had my new system a week but WOW, sounds great. JL is a leader in marine sound technology and the best part ,made in USA. I'm going to add their 8'' subwoffer to my system.

Pros: Extremely well made and out performs my expectation .

Cons: None

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1 of 1 found this helpful

JL Audio M400/4 INCREDIBLE CLARITY

Joe from Lenoir city, TN on 3/6/2016

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Easy installation, the unit will handle just about any input signal including line out from the stereo unit. The wire terminations are very secure and solid all included tools (allen wrench) are provided to terminate wires and secure them. Great clarity and very easy to set up for all audio sources, as long as you have a multi-meter to read the AC voltage.

Pros: Easy of installation Easy to configure Very well thought out design

Cons: None so far but had the unit only a couple of weeks.

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1 of 1 found this helpful

Great amp for rzr1000 xp4

Crutchfield customer from Scottsdale, az on 5/16/2015

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Great amp for my rzr. Small with lots of power. Easy to install

Pros:

Cons:

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3 of 3 found this helpful

Outstanding couldn't be happier

Fourwinns from Wichita Falls TX on 4/17/2015

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I bought this item as scratch and dent.. I couldn't find a scratch not dent on the amp. Wired 4 JL MX650's to my head unit first and was disappointed (obviously) then plugged in the speaker wire I had run for the amp. 100x better clearer and LOUD! I probably have the perfect amp for those particular four speakers but the difference was incredible, not to mention the sound is amazing. I highly recommend ALL JL AUDIO MARINE products they're in my opinion the best you can get.

Pros: Good power, no noise, great sound

Cons: Haven't found any cons so far

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2 of 2 found this helpful

Awesome tiny-mite!

Chris from Katy, TX on 3/13/2014

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Powering two jl 7.7 coax's and two channels bridged to power the 10" open baffle sub in our little ski boat and it plays detailed, soft and load, and it puts out clean undistorted full range watts!

Pros: Small easy to hide

Cons: Forget it's there!

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2 of 2 found this helpful

M400/4 amp

Oz from Frankfort, Ky. on 9/8/2012

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Installed JL amp for my boat , sounds great and after 5 hours of playing music, the amp wasn`t hot. Will tell family and friends.

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3 of 3 found this helpful

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Product Research

Features
Controls
Connections

Features

4-Channel Full-Range Amplifier: The JL Audio M400/4 is a four-channel, full-range audio marine amplifier utilizing NexD ultra-high speed switching technology to deliver outstanding fidelity and efficiency. The M400/4 can be operated with a wide variety of source units and system configuration.

Marine Amplifier: The JL Audio M-series marine amplifiers are specifically designed for marine applications. These amps are not waterproof, however, and should not be mounted where they are likely to get wet.

Amplifier Rating: The JL Audio M400/4 Class D 4-channel marine amplifier is rated at 75 Watts RMS x 4-channels in 4-ohm at 20 to 20,000Hz with a signal-to-noise-ratio of 104 dB and a total harmonic distortion of 1% while receiving 14.4 Volts.

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

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

Differential-Balanced Inputs: The JL Audio 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 12-volt installation.

Note: You will need two speaker wire to RCA adaptors (136XDCLR2S, sold separately) to connect this amplifier to your headunit 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 M400/4 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 M400/4 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 control panel security cover is pre-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 screws.

Simplified Gain Setting: The M-series amplifier makes setting the gain level of the amp via the input sensitivity control very simple. All you need is Digital AC Voltmeter (142TK12V, sold separately) and a Test CD Disc (503CD104, 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 (50 Hz for subwoofer channels, 1 kHz for a midrange application).

Note: The M400/4 is equipped with a independent gain controls for the Front (1&2) and Rear (3&4) channels.

Flexible Input Section And Active Crossover Network: The JL Audio M-series amplifier provides a flexible input section and a comprehensive crossover network to fine tune your system effectively and accurately. The variable filter design employed in the JL Audio M-series amplifier crossover sections allow you to seamlessly switch slopes, easily change filter frequencies and address what frequencies the preamp inputs will pass. The M400/4 offers the following independent crossover adjustments for the front and rear channels along the unit's top panel, behind a removal cover plate.

  • Input Mode: This switch allows operation of all four amplifier channels with only one pair of input signals (2-CH Input Mode) or with independent front and rear input signal pairs (4-CH Input Mode). You will only need to connect the front RCA inputs when placing the amplifier in 2-CH input mode.
  • Filter Mode: The amplifier allows you to select either a Low Pass, High Pass or Full-Range operation of the amplifier's 1 & 2 channels and 3 & 4 channels.
  • Variable Frequency: You can set the amplifier's Low Pass or High Pass crossover from 50 to 200 Hz for channels 1 & 2 and channels 3 & 4.

Connections

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

  • Power and Ground: The JL Audio amplifier's set-screw Power and Ground connections are designed to accept 8 to 4 AWG power wire. A 2.5mm Allen wrench is supplied for making connections.
  • Remote Turn-On: The JL Audio M-series amplifier's set-screw turn-on lead will accept 18 to 8 AWG wire. The same 2.5mm Allen wrench is supplied for making connection.
Note: The Amplifier is not equipped with a fuse. An external 40-amp AFS, AGU, or MAXI fuse (not included) 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 M400/4 amplifier's eight set-screw speaker terminals will accept 16 to 8 AWG speaker wire. A 2.5mm Allen wrench is supplied for making connections.

Preamp Inputs: The amplifier features two sets of differential-balanced RCA jack inputs. The amplifier features a dedicated Input Sensitivity gain control for the front and rear channels of the amplifier. These controls are designed to match the input sensitivity of the M400/4 to the specific signal source that is feeding it. The amplifier's input level can be set independently for the front and rear channels between 100mV-4V.

Preamp Outputs: The M400/4 incorporates a pass-through preamp output sections, so that additional amplifiers can easily be connected to the same signal(s) feeding the M400/4. These preamp output signals are buffered to prevent noise and are always preamp level, regardless of the level of signals feeding the M400/4's inputs. The amplifier's set of preamp outputs can be configured two different ways.

  • Front (1&2): The preamp output delivers the same signals that is connected to the M400/4's front RCA inputs. This mode is useful for feeding a subwoofer amplifier when the M400/4 is being used to drive front and rear speaker system. In this mode, the preamp output level will track with the signal level of the front input signals, allowing you to fade the rear channels in and out, without affecting the subwoofer level.
  • Sum (F+R): This mode delivers a sum of the signals being fed to the front and rear RCA inputs of the amplifier. When the M400/4 is being used to drive front and rear speaker systems, this preamp output mode will deliver a summed front/rear signal to the subwoofer amplifier, while permitting fading of the front and rear speaker system from the source unit.

Remote Level Control: The amplifier features a standard telephone connector for adding an optional wired remote level control. With the addition of the optional wired Remote Level Control (136HDRLC, sold separately), you can control the volume of one or both channel pairs of the M400/4 form the front of your vehicle. This is useful for subwoofer level control or even as a master volume control for your system. If desired, multiple M-series amplifiers can be controlled from a single HD-RLC controller using a simple phone line splitter and multiple phone cables (all sold separately).

Note: All inputs and outputs are located on one side of the amplifier to make installation of the amplifier simple and neat.

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Customer Q&A

Q
Crutchfield asked: Why did you buy this?
A
I have many JL Audio amps and speakers. They have only let me down once. [ STEPHEN  Feb 18, 2019 ]
A
I wanted JL But Bryce's Recommendation put the seal on the deal on which model [ JOHN  Aug 04, 2018 ]
A
Real happy with JL Audio products [ Keith  Jun 30, 2018 ]
A
Recommended by my marine electronics installer to add to existing system [ Jorge  Jul 18, 2017 ]
A
Highly recommended by other boaters [ Steven  Apr 25, 2017 ]
A
Ringo recommended Ringo's Bio: http://www.crutchfield.com/Support/Bio.aspx?bio=164 [ Anton  May 12, 2016 ]
A
Best bang for the buck with great reviews. [ Randy  Apr 30, 2016 ]
A
Great power [ Corey  Mar 13, 2016 ]
A
to power two jl audio 10 inch subs [ Keith  Mar 07, 2016 ]
SHOW MORESHOW LESS

2 questions already asked

Q
Does the m400/4 have an internal fuse?
[ Justin  Jun 26, 2016 ]
5 answers
A
No
[ Kevin  Jun 28, 2016 ]
A
No internal fuse that you should have to replace. These units are designed to have customer supplied fuse that is installed near source of power
[ woody  Jun 28, 2016 ]
A
Not that I am aware of ; instructions are specific about installing one ahead of the unit in the power feed
[ NEIL  Jun 27, 2016 ]
A
YEs
[ ROBERT A  Jun 27, 2016 ]
A
Yes
[ JOHN  Jun 27, 2016 ]
Q
Does m400/4 have to be floor mounted in boat?
[ Jesse  Jul 25, 2015 ]
6 answers
A
No, I mounted it a a vertical 'wall'.
[ Gregory  Jul 27, 2015 ]
A
i mounted mine vertically in side a closet
[ DAVE  Jul 27, 2015 ]
A
No it can be mounted anywhere
[ Steven  Jul 26, 2015 ]
A
You can mount this amp pretty much anywhere you want. Just make sure it won't get wet. I mounted the amp in my electronics box in my T top. Very happy with amp
[ richard  Jul 26, 2015 ]
A
no. it can be bulkhead mounted.. in ur instructions manual it will tell you it is the preferred mount.. mine is under my m600.6 n over my m600.1..
[ GEORGE  Jul 26, 2015 ]
A
No
[ Jesse  Jul 26, 2015 ]

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