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JL Audio JX400/4D

4-channel car amplifier — 70 watts RMS x 4

Item # 13699401

JL Audio's JX400/4D 4-channel amplifier delivers 70 watts RMS to each of your car's front and rear speakers so...

JL Audio's JX400/4D 4-channel amplifier delivers 70 watts RMS to each of your car's front and rear speakers so...

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About the JL Audio JX400/4D

Power your music

JL Audio's JX400/4D 4-channel amplifier delivers 70 watts RMS to each of your car's front and rear speakers so you'll hear and feel your music clearly over the noises of the wind and road. You can also switch over to 2-channel mode, and power a pair of subwoofers with 200 watts RMS each, and fill your ride with bass.

Power your music

JL Audio's JX400/4D 4-channel amplifier delivers 70 watts RMS to each of your car's front and rear speakers so you'll hear and feel your music clearly over the noises of the wind and road. You can also switch over to 2-channel mode, and power a pair of subwoofers with 200 watts RMS each, and fill your ride with bass.

Convenient features

JL Audio JX400/4D

Variable high- and low-pass filters allow you to tune the amplifier to match your particular speaker or subwoofer system. The amp includes speaker-level inputs, along with preamp inputs and outputs, so it's ready to work in virtually any system.

Rugged construction

JL Audio designed this hefty little amplifier with sturdy, high-grade parts that ensure excellent heat management, provide high current flow, and deliver stable performance in almost any situation. Inside, you'll find oversized output transistors and a rugged MOSFET power supply; outside, the sleek, high-mass aluminum heatsink keeps things cool enough to virtually eliminate thermal shut-downs.

JL Audio JX400/4D

JX400/4D input and control panel

READ LESS

Product highlights:

  • 4-channel car amplifier
  • 70 watts RMS x 4 at 4 ohms (100 watts RMS x 4 at 2 ohms)
  • 200 watts RMS x 2 at 4 ohms
  • Class D amplifier design
  • frequency response: 20-20K Hz
  • variable high- and low-pass filter (50-200 Hz, 12 dB/octave)
  • preamp inputs and outputs
  • speaker-level inputs
  • wiring, fuse, and hardware not included with amplifier
    • 4-gauge power and ground leads and a 40-amp fuse recommended
  • 9"W x 2-3/16"H x 7-11/16"D
  • warranty: 2 years
  • Our 60-day money-back guarantee
  • MFR # 99401

What's in the box:

  • 4-Channel amplifier
  • Two 10" speaker-level harnesses
  • 2.5mm Allen wrench
  • 4 Self-tapping screws (3/4" length)
  • 4 Flat washers
  • Owner's Manual

Customer reviews

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JL Audio JX400/4D reviews

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Solid!

Brad from NC on 9/12/2019

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Very solidly built amplifier! Cosmetically pleasing to the eye as well. Solid connections and simple controls. Plenty of power to run coaxials, components, a small subwoofer, or a combination of the three. I am using this unit in 3 channel mode to power a set of JL Audio C1 coaxials and a 6.5 inch JL Audio Microsub in a single cab Ford Ranger. It produces super clean sound quality that gets surprisingly loud. JL Audio's entry level equipment easily rivals other manufacturers mid to high end equipment. I wouldn't own anything else.

Pros: Power, build quality, simplicity, good looks

Cons: None

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0 of 0 found this helpful

JL Audio JX400/4D

Crutchfield customer from Bonaire, GA on 7/8/2019

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Really like this amp. Hooked this up to my door speakers in my F150 crew cab. Easy install and works great.

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0 of 0 found this helpful

Clean and LOUD

Crutchfield customer from Las Vegas, NV on 5/30/2019

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This amplifier is perfect for my sound system in my truck. Powers all four door speakers nicely with plenty of volume without distortion. Clean sound and LOUD as can be. The size of actual unit is perfect, not too big not too small. And throw in to of all that it comes with a two year warranty. I'd definitely buy it again and recommend to anyone who wants clean, loud sound.

Pros: Clean sound

Cons: None

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0 of 0 found this helpful

Great Amp

Crutchfield customer from Colorado Spgs, CO on 4/22/2019

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Great quality, awesome amp. I used this amp to power the factory speakers in my F150. It makes the factory speaker come alive and sound great. Will work great with later speaker upgrades. You can't beat it at this price.

Pros: Looks great, easy to install, speaker level inputs, adjustability, great price

Cons: None

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2 of 2 found this helpful

Bang for the buck

Dustin from Centerton, AR on 3/7/2019

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This JL Audio amplifier may not be their top of the line offering but you cannot tell that by the soind. This amp has exceptional sound clarity at high volumes when paired with the JL C2 speakers.

Pros: Size, sound quality, easy of installation.

Cons: None so far.

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3 of 3 found this helpful

JL Audio JX400/4D

Crutchfield customer from Cerritos, CA on 2/27/2019

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Such an awesome Amp, the power it delivers for only 400 watts is astounding. Very happy with this purchase and with all the people at Crutchfield for their knowledge in helping me to decide upon this product.

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2 of 2 found this helpful

Great amp

Jeremy from Timberlake, NC on 2/23/2019

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Very happy with the product! I was even more happy with the price. I definitely will be buying more products from crutchfield!!!

Pros: Great price. Received the product quick.

Cons: None.

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1 of 1 found this helpful

Perfect power and size!

Crutchfield customer from Glendale, AZ on 1/24/2019

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Nice little amp! I have it powering 4 C2-525x jl's and they sound amazing in my 2011 F150 XLT along side my JL JX 500 powering 2 8 inch JL W3V3 subs (CP208LG-W3v3)

Pros: Compact

Cons: None

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1 of 1 found this helpful

JL Audio JX400/4D

Crutchfield customer from Seguin, TX on 1/15/2019

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Great little amp, Good compact size to fit in tight spaces.

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0 of 1 found this helpful

JL Audio JX400/4D

R.O. from Conway, SC on 11/25/2018

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Amp is clear but lacks on power. Over all it works good

Pros: Clear sound

Cons: Low on power

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2 of 3 found this helpful

JL Audio JX400/4D

Crutchfield customer from Green River, WY on 10/23/2018

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This was a big improvement over the Kenwood amp. that you sold me at first. Sound is crisp and full.

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2 of 2 found this helpful

JL Audio JX400/4D

Crutchfield customer from Bridgeport, TX on 10/14/2018

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Finally got an amp to push my upgraded door speakers and it does the job nicely

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1 of 1 found this helpful

70 Watt RMS is a LOT of power

Nate from Glastonbury, CT on 10/1/2018

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I was advised to pair this with a set of JBL Club Component 9600C speakers and a set of Morel Maximo Coax 6 in my 2012 Nissan Rogue. I had an aftermarket Chinese brand Android Auto Head Unit sending power and after the amplifier was installed, man did those speakers come to life! I had no idea what was housed in my doors until this Amp started making those speakers really sing and pump out the bass and volume. I had the amp professionally installed and noticed that the gain was turned down so low and still it was so powerful. The sounds coming out are clean, no distortions, and even at high volume it sounds amazing. This is my first amp ever in my life and going through a mid-life crisis right now, I definitely made the right decision going with JL Audio. I have a feeling anything else would sound inferior to me going forward. I had this mounted on the back seat of my SUV and it looks so cool every time I look in the window or through the back. I'll probably need to get near black window tint as the JL Audio brand is very prominent and will catch the eye of any hungry audiophile with questionable ethics.

Pros: Lots of power, sounds clear, looks great, quality product.

Cons: None.

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9 of 10 found this helpful

JL Audio JX400/4D

Aubrey L. from Hephzibah, GA on 8/28/2018

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Exactly as described.

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1 of 1 found this helpful

JL Audio JX400/4D

Crutchfield customer from Annapolis, MD on 8/27/2018

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great amp, was not quite enough power to bridge channels and power my JL 12w3 sub as much as desired but still an excellent amp for speakers.

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0 of 2 found this helpful

Clarity that is unmatched

John from Mattituck, NY on 6/29/2018

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This amp has great audio quality and packs a punch. The built in equalizer is simple to use for fine tuning the audio.

Pros: Sound quality and adjustability

Cons: High level inputs over drive the bass a little.

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1 of 1 found this helpful

Does not last

William from Bozeman, MT on 6/12/2018

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This amp did not last. A little after a year, it started cutting out and I had a lot of static when it did work. I'm very disappointed. I did not abuse this amp.

Pros: Good sound

Cons: Not durable

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4 of 6 found this helpful

Great Sound!!

Charles from Hillsborough, NJ on 5/25/2018

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This amp works perfect!! Easy installation and the sound quality, paired with the JL C2-650 component speakers in front and the C2-650 2-way speakers in the rear deck it sounds wonderful!!

Pros: Easy setup and installation and great sound quality! Perfect for my 2018 Civic

Cons: None so far

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3 of 3 found this helpful

JL Audio JX400/4D

Griffin from New Hampshire on 3/26/2018

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This amp is perfect. Plenty of power and easy to install. However, this is not a plug and play amp. It takes a little tuning. Once tuned, it sounds clear and clean mids, with tight, warm midbass. Another great JL product!

Pros: Sound Durability Size Power

Cons: Tuning can take some time

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4 of 4 found this helpful

Perfect!

Steve from Plainfield, IN on 3/8/2018

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Small, affordable, works perfect!

Pros: Price, size, clean abundant power

Cons: none

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0 of 1 found this helpful

Static

Dan from Sacramento, CA on 1/12/2018

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Unfortunately, the left and right channels that supply my front speakers have intermittent static on them. I swapped them with the rear channels and the problem went to the backs. I even moved my ground and had the same result. I took longer then expected to get my install complete which put me outside the warranty period. Unfortunate as I love JL Audio.

Pros: Clean sound from the channel that works

Cons: Static coming from amp.

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1 of 4 found this helpful

JL Audio JX400/4D

Crutchfield customer from Parker, CO on 11/26/2017

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Solid sounding amp. Easy to connect to my speakers. Grrat for the price

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0 of 0 found this helpful

JL Audio JX400/4D

Crutchfield customer from Ellijay, GA on 11/24/2017

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Not as much power as I expected from this amp. I have a 20 year old US AMP 100 (50x2) that is stronger than this amp.

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4 of 9 found this helpful

JL Audio JX400/4D

Keith from Oak Lawn, IL on 11/18/2017

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Great amp powering my 6.5 in jbl gto speakers. Really clear powerful sound only have it set half way.

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1 of 1 found this helpful

JL Audio JX400/4D

Jordan from Endicott, NY on 11/17/2017

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Works amazing!

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0 of 1 found this helpful

JL Audio JX400/4D

Sam from dunkirk, ny on 10/1/2017

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wired up a set of speakers to this amp in my 12 f150. easy setup, small, and works great.

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3 of 4 found this helpful

Was expecting more from this JL amp

Crutchfield customer from Palm Bay, FL on 9/29/2017

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I was expecting a bit more from this amp. I paired it with a set of Kicker component speakers and Kickers in the back doors and they could be the weak link here. Maybe with more use and adjusting I can get it where I like it. But really not what I was expecting from JL.

Pros: Price and small size.

Cons:

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0 of 4 found this helpful

JL Audio JX400/4D

Allen from Cleveland, TN on 9/21/2017

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Great amp. Cleaned up sound and really works well in my Jeep TJ after upgrading factory speakers. Paired with 4 Kicker 5.25 inch speakers.

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2 of 3 found this helpful

JL JX not enough power

Mario from Sahuarita, AZ on 8/24/2017

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This amp was recommended by Crutchfield staff to power focal IS570 for the front channels, and bridge the JL 8w3v4 sub for the rear. this amp doesn't put nearly enough power at 12v and can barely keep up with 13.5v. when the truck is on. I couldn't even get the sub to sound or move without some seriously clipping. It has since been returned. If you are looking for something to power a front stage i would only recommend this amp to bridge a couple front channels at about 150-180 watts.

Pros: small footprint is a plus

Cons: read the fine print for the rated power. I didn't notice until after i installed.

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0 of 8 found this helpful

JL Audio JX400/4D

Doug from Vinita, OK on 8/21/2017

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Everything JL Audio is great, and Crutchfield is awesome with their service and support!!!

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1 of 2 found this helpful

JL Audio JX400/4D

Crutchfield customer from Kalamazoo, MI on 8/7/2017

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Excellent product. Strong clear power.

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2 of 2 found this helpful

JL Audio JX400/4D

Chris from Cape Neddick, ME on 7/25/2017

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Works awesome.

Pros: Great product. Very fast shipping.

Cons: None

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2 of 3 found this helpful

JL Audio JX400/4D

Noe Ramirez from Hebbronville, TX on 6/25/2017

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It was awesome product details about amp were excellent and quality is excellent easy installation I would recommend anyone to purchase it..

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3 of 3 found this helpful

JL Audio JX400/4D

Jacob from Michigan on 6/21/2017

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Never had a 4 channel amp before the jL was installed in my 76 Grand Prix I installed 2 Jl audio 6x9 3-way speakers along with 2 pioneer 6x9 3-way speakers and I really like the sound I'm going to upgrade the pioneers to another pair of JL's eventually I'm pushing 70 watts per speakers with a set of 10 p 2 in the truck... the jl audi amp just makes me want to add more thanks for the advice their worth the money

Pros: Very small easy installation price was right

Cons:

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3 of 3 found this helpful

JL Audio JX400/4D

Jose from Rio Grande, PR on 5/28/2017

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This amp is well worth the money worked very well with my full range alpine speakers and alpine navi head unit sound is clear takes a little time to fine tune but once you FT the sound quality is awesome

Pros: Small compact great sound quality lots of power

Cons: None that I could find

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2 of 2 found this helpful

This was a GOOD buy.

Crutchfield customer from Longmont, CO on 5/21/2017

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This was a GOOD buy. The mids and highs are clearer (sharper) than with a previous amp I had in the car. The fact that you can tune the amp to your system adds to the sound quality. I call tech support a couple times before actually making the purchase, and then made the purchase because of their help. I didn't know if my head unit was capable of connecting to a 4-channel amp, and didn't want to pull it just to find out. They looked it up and explained what I had and how to connect to the JL Audio amp for the best performance. They're great. When the time comes that what to build or upgrade another system, I'll call them first.

Pros: mids and highs are clearer (sharper) than with a previous amp, and the tech support folks are great.

Cons: none

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4 of 5 found this helpful

JL Audio JX400/4D

Orlando from Albany,N.Y. on 4/2/2017

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Awesome amp,small and packing enough power.This is the best amp I've used so far,I recomend it to everyone who wants continuously music for long periods. Amazing.

Pros: Works for long periods. Small in size,you can install anyware in you vehicle.

Cons: No cons so far.

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1 of 1 found this helpful

JL Audio JX400/4D

Crutchfield customer from Concord, NC on 4/1/2017

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Very solid & musical amp. Takes a bit of time to get all of the levels and crossover points set, but once you do it the sound is great. I have it driving a set of Infinity Kappa components in the front and coaxial Kappas in the rear & this amp has enough headroom to make your ears bleed with absolutely no distortion or harshness. All in all, a great sounding amp.

Pros: See review above.

Cons: None so far.

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5 of 5 found this helpful

Great amp

Sostenes from Mankato, MN on 3/19/2017

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For a small amp it sure packs a nice punch and for the price. Great amp I would recommend if you are looking for an amp for your front speakers

Pros: Small if you are working with little space

Cons: N/A

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2 of 2 found this helpful

JL Audio JX400/4D

Crutchfield customer from Birmingham, Al on 3/5/2017

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I use this amp to power Infinity componets and coaxial speakers. If your looking for a quality 4 channel amp...this is the one.

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Cons:

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2 of 2 found this helpful

Job audio amps

Tracy from Everett, WA on 10/9/2016

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I bought my Kenwood DNX571-TR- navigation- receiver with 4 Alpine SPR-68 6x9s Which sounds so great, but I was missing one thing, for me, I'm old school rock and roller of the 60s & 70s. I needed more , so I added a JL Audio JX1000/1 another 1000 watts to power my 2 10inch Kicker Comps in my 98 f-150 extended cab. All of what I have done has gave me everything I needed as for power , sound quality and clarity of all the music that I listen to.i am so happy for everything that is installed , and I am pleased about this investment. Heck I'm still rocking at 59 years old, and I've never stopped for one minute. Young at heart and still love my toys.

Pros: I about have it all for now.

Cons: I will find out when I can't hear when I go deaf... lol

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10 of 11 found this helpful

JL Audio JX400/4D

David from Dover, DE on 6/28/2016

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When I took this amp out of the box, I was a bit surprised at how small it looked, but quickly remembered that it is a class D amp. Once I got it hooked up to drive my front and rear speakers I quickly remembered what great products JL Audio makes. I spent about forty-five minutes getting it dialed in, and sat back and enjoyed the greatness of JL Audio. This the sixth JL amp I have owned, and I love it.

Pros: Excellent Amplifier. Spend the necessary time to get it properly dialed in.

Cons: None

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3 of 3 found this helpful

Love it so far!

Paul from Irvine, CA on 6/6/2016

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Loving this amp so far! Clean looking, easy to operate and hook up, and gives great boost!

Pros: POWER Clean Efficient

Cons: Smallest tiniest littlest chip in the glass decorative part. But under the seat no one will notice.

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2 of 2 found this helpful

JL Audio JX400/4D

Luis S from El Paso, TX on 4/1/2016

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I updated my trucks entire sound sound system. Pioneer DVD player Stereo, XM radio, Four Pioneer Door speakers 6.5 inch and the amplifier. No subwoofer yet. After dialing in the sound I am very pleased with the amplifier. I like clean, powerful, low to mid volume sound

Pros: 1. Fits under the drivers seat 2004 Toyota Tundra double cab. 2. Good clean powerful sound. 3. Volume is easily loud enough for inside the car listening at 50% and sometimes up to 75% volume levels. Low fatigue. HPF filters turned off. No subwoofer.

Cons: 1. I have owned the product for only 1 month. No cons to report at this time. Nothing to compare it to except my Home Hi Fi Stereo system and the old car stereo before the amp was installed.

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5 of 6 found this helpful

JL Audio JX400/4D

mattesjl from easton,pa on 3/13/2016

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great amp, easy to adjust the settings, plenty of power

Pros: nice power, easy to install and adjust

Cons:

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2 of 3 found this helpful

Nice Output for a Compact Amp

Mopo from Seattle on 2/17/2016

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Placed this under the driver seat in a 2011 WRX Wagon. I had plenty of space for all the wiring and a distribution block next to it. I am powering Focal Performance PS 165V (filters off) and 165AC (HPF on). I have not played with the gain or filter settings, so I believe there is still a lot more power I can draw from the amp. My speakers come in loud and clear; almost too much for my wimpy compact sub. I am sure it is some settings I need to play with.

Pros: -Nice construction -Plenty of Output power -Easy to install -Compact size

Cons: -Not sure if the "Input Sensitivity" is the same as gain? -The remote/turn-on lead port was almost too large for the 18 gauge wire I used. The screw they use to lock down the wire is not good for smaller gauge wires. I would recommend some kind of wide end-connector instead of bare wire.

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3 of 3 found this helpful

Good performance

Mark from Florida on 1/17/2016

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Well built unit. Sounds great driving a JL CP108LG sub and JL C3 speakers in a single cab full sized truck. Plenty of power.

Pros: Small, stays cool, plenty of power.

Cons: None

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4 of 4 found this helpful

Amp install of 94 MR2 "Frunk"

Sean M from Massachusetts on 11/3/2015

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Seems like a solid amp so far. Not really pushing it to hard but it is so much smaller and generates so much less heat than the Sound Ordnance amp I had before. The SO amp would go into thermal shutdown if I pushed it hard. This amp seems fine. Running front 6.5 inch components in the front doors and a pair of 6.5 inch subs in the factory boxes behind the seats. Probably could be a little less expensive for what it is, but it seems solid.

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8 of 8 found this helpful

Big sound, small package

JCS from Lexington, Virginia on 9/18/2015

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Hard to believe such clean, overwhelming power could come from such a small and lightweight package, but it does. Running in 2-channel bridged through a pair of Polk 6x9's, and the thing nearly knocks me out of my truck. Crisp highs and non-distorting lows. Love the cross-over options as well as pre-amp input level adjustments. An awesome deal for a very reasonable price.

Pros: Clean, compact design. Lug-style attaching screws. Adjustable input level controls. Adjustable cross-over frequency settings. Can run with hi-pass, low-pass, or no filtering. Two-channel, 4-channel switch.

Cons: Power and Overload lights are on the side opposite of the power and speaker wire inputs (not really a "con" as much as it is an inconvenience). No internal fusing; must purchase an external in-line fuse, which can be pricey. Instructions in the manual for two-channel bridging can be confusing for those not familiar with the technique.

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7 of 7 found this helpful

Great quality

Miguel Angel from PR on 9/4/2015

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Great quality easy installation

Pros: Good size

Cons: None

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4 of 6 found this helpful

JL Audio JX400/4D

Crutchfield customer from Florida on 8/25/2015

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Good product, worth it.

Pros:

Cons:

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6 of 6 found this helpful

Bang for buck amplifier!

RyanW from North Dakota on 8/8/2015

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This amp is powering 4 6x8 infinity kappas in my doors. I also installed dynamat in the doors of mazda 6 at the same time. I couldn't be happier with the results. Sure there are more expensive amps out there. But this puts out 100x4 at 2ohms and that's what I'm running them at. This system screams at me waaaay louder than any human could possibly take. My system sounds so clean and so punchy. I don't feel I need subs. Just the perfect setup for me. My rear view mirror does shake when bass and drums hit. So it's definitely powerful enough for me.

Pros: Affordable, plenty powerful enough, very clean and crisp well balanced sound.

Cons: Can really think of any? They do make more expensive and more powerful amps though.

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10 of 10 found this helpful

jx400 amp

steveB from Texas on 6/8/2015

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Always nervous after new up grade from factory equipment.Could not be happier with the power and clarity of my newly installed and jx400 amp .

Pros: Plenty of power to easily drive my new 6x9s.Cranked it up and it blew me away. Asked an installer what he thought,he said he was very impressed.

Cons: None

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11 of 11 found this helpful

jx400.4

dylan from Kerrville tx on 5/7/2015

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I gave it 3 starts out of high quality standards. You kind of get what u pay for here. I would like to extend 3.2 or possibly 3.5 stars. I have the gains set at a moderately safe level, yet it could be louder. I'm pushing 2 rockford fosgate pps4-6 and two rockford fosgate t165. The amp does supply exceptional quality and at the settings it's on does not over heat to the touch. Warm. the 4 speakers equal 340w rms total. This amp won't supply that. But it is loud. Decent to exceptional quality and no over heating. Good for the money. Itd b great a $200, but u can't win them all. Good buy.

Pros: Good quality no over heating loud enough

Cons: Doesn't not supply full 400w (in my opinion )

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Pros:

Cons:

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Product Research

Features
Controls
Connections

Features

Four-Channel Class D Amplifier: The JL Audio JX400/4D is a four-channel, full-range amplifier utilizing Class D technology. The JX400/4D can be operated with a wide variety of source units (aftermarket or factory) and system configurations (4-channel, 3-channel, or 2-channel).

MOSFET Switching Power Supply: The amplifier employs a rugged MOSFET power supply for outstanding reliability and operational stability.

Amplifier Ratings:

  • Rated Continuous (RMS) Power @ 14.4V:
    • 70 watts x 4 channels at 4Ω
    • 100 watts x 4 channels at 2Ω
    • 200 watts x 2 channels at 4Ω bridged
  • Rated Continuous (RMS) Power @ 12.5V:
    • 50 watts x 4 channels at 4Ω
    • 80 watts x 4 channels at 2Ω
    • 160 watts x 2 channels at 4Ω bridged

Protection Circuitry: The JX400/4D's protection circuitry automatically shuts the amplifier down if thermal limits are exceeded, a short-circuit is detected in the speaker wiring, or if a dangerously low impedance is connected to the amplifier. Once the problem is corrected, the amplifier will return to normal operation.

Status Indicator Lights: There are two status indicator lights on the right side of the amplifier.

  • Power (Green): This LED lights green to indicate that the amplifier is turned on and operating normally.
  • Protect (Red): The Protection LED lights Red to indicate the amplifier's protection circuitry has been activated.

Controls

Input Sensitivity: The four-channel amplifier's Input Sensitivity Control is used to match your source unit's output voltage to the input stage of the amplifier for maximum clean output.

  • Low-Level Input Range: 200mV-4V (RMS)
  • High-Level Input Range: 2V-10V (RMS)

Input Mode: You can send four discrete channels of input into the amplifier, or feed all four channels with only two channels of input. The Input Mode switch has two positions: 4 Ch. for discrete 4 channels of input or 2 Ch. for feeding four channels with the inputs to Channels 1 & 2.

Variable Crossovers: The JX400/4D has a defeatable 12dB/octave filter for each channel bank. The crossovers can be configured as a low-pass or high-pass filter with a continuously variable cutoff frequency from 50 to 200 Hz.

  • Filter Mode: The amplifier has independent 3-way switches that allow you to select either a Low Pass (LP), High Pass (HP) or Full-Range operation (Off) for Channels 1&2 and Channels 3&4.
  • Filter Frequency: Separate rotary dials let you set the cutoff frequency between 50 to 200 Hz for each channel bank.

Connections

Power/Ground/Turn-On Terminals: The JX400/4D features set-screw terminals for the power, ground, and remote turn-on connections:

  • Power and Ground: The set-screw Power and Ground connections are designed to accept up to 4 AWG wire. A 2.5mm Allen wrench is supplied for tightening/loosening connections.
  • Remote Turn-On: The set-screw turn-on lead will accept 18 to 10 AWG wire. The same 2.5mm Allen wrench is supplied for making the connection.
Note: The Amplifier is not equipped with a fuse. An external 40-amp fuse (not included) must be installed on the power wire within 18" of the positive battery post. 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 JX400/4D amplifier's eight set-screw speaker terminals will accept 16 to 8 AWG speaker wire. The amplifier's speaker terminals can be wired in a four-channel or bridged two-channel configuration. The 2.5mm Allen wrench is supplied for making connections.

Preamp Inputs: The amplifier features two sets of stereo RCA input jacks. The amplifier features a dedicated Input Sensitivity gain control for each pair of inputs. These controls are designed to match the input sensitivity of the JX400/4D to the specific signal source that is feeding it. The amplifier's low-level input can be set between 200mV-4V RMS.

Speaker Level Inputs: The JL Audio JX400/4D also accepts speaker level signals, including those from factory systems (without the need for a line-output converter), via the supplied supplied speaker-level harness. The head unit's speaker wires should be spliced to the speaker-level harness. The amplifier's high-level input can be set between 2V-10V RMS.

Preamp Outputs: The JX400/4D incorporates a pass-through preamp output sections, so that additional amplifiers can easily be connected to the same signal(s) feeding the amplifier. These preamp output signals are buffered to prevent noise and are always preamp level, regardless of the level of signals feeding the amplifier's inputs.

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Customer Q&A

Q
Crutchfield asked: Why did you buy this?
A
For highs and lows [ Richard  Apr 04, 2019 ]
A
I am very interested in high quality sound [ Demond  Mar 13, 2019 ]
A
I chose this amp to power 2 pairs of Infinity 6-1/2s with a RMS rating of 55W each. This amp was the best bang for the buck within the range I was looking for. Cant go wrong with a JLAudio product for $200 and a great review rating. [ Hosh85  Feb 16, 2019 ]
A
Clarity [ Anushh  Feb 12, 2019 ]
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Because they're the best [ Larry  Jan 16, 2019 ]
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because your advisor recommended it [ Elliott  Jan 06, 2019 ]
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Recommended by sales rep. [ Alvin  Dec 12, 2018 ]
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Crutchfield tech Bernie assisted with purchase and did an outstanding job [ Tristan  Nov 27, 2018 ]
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I have the jl systems for my can am spyder [ Calvin  Oct 07, 2018 ]
A
Great price. [ MAURICE  Sep 25, 2018 ]
A
JL Audio is known for high quality. Drew from Crutchfield explained about the signal to noise ratio and that it would be clean and not to exceed my power ratings on the speakers. After searching and researching it was relief to hear sound advice from experts that know what they are talking about. I would rather buy from Crutchfield than anywhere else because of the exceptional return policy and technical support. [ Srinath  Sep 15, 2018 ]
A
JL Audio quality that fits my budget. Prefer the full sound from using fronts and rears. [ ANTONIO  Jul 26, 2018 ]
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On Sale & the expand-ability & JL Audio [ S  Jul 05, 2018 ]
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Prior experience [ Aaron  Jun 04, 2018 ]
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Enough power, great brand and an awesome deal. [ Eduardo  Jun 01, 2018 ]
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Nice quality amplifier for the money! [ John  May 23, 2018 ]
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top rated [ ALAN  Apr 18, 2018 ]
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replacing my mach system in my mustang and needed a 4 channel amp [ Donald Scott  Feb 15, 2018 ]
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I read the reviews and I also talked to Hogan about this amplifier so that's why I went with it [ Erik  Jan 05, 2018 ]
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Nice [ Chris  Dec 22, 2017 ]
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Otis [ Scott  Sep 21, 2017 ]
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Price and quality. [ Pete  Sep 01, 2017 ]
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Great amp. [ DEWAYNE  Aug 23, 2017 ]
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To replace discontinued JL 320 [ David  Aug 15, 2017 ]
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I currently have a JL Audio Mono block that I use for my subs. I felt that this amp would be a great compliment to the mono block. [ ROBERT  Jun 27, 2017 ]
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Dolly [ Peter  Jun 14, 2017 ]
A
Dexter made the recommendation and said it would be a good fit for my other components. The amp seems to have good specs and is reasonably priced. [ Kemper  Jun 07, 2017 ]
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I've heard nothing but great reviews about this product. Besides JL rocks! [ K  Jun 01, 2017 ]
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Cj at tech support !!! [ Jeff  May 10, 2017 ]
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Love jl [ Steven Frederic  May 06, 2017 ]
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To add clarity to the JL Audio 6x9 and component speakers I purchased. Should be rockin'! [ William  Apr 19, 2017 ]
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Positive product reviews and recommended by a friend [ Kevin  Feb 18, 2017 ]
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Good power to money ratio. Needed an inexpensive 4 ch. amp. [ AMAURY  Feb 01, 2017 ]
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because of there reputation of good audio,I was not disappointed,this amp does as advertised,maybe more [ paul  Jan 14, 2017 ]
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Great amp excellent size [ Squire C.  Nov 28, 2016 ]
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Great addition to my system and at a great price [ Steven  Oct 05, 2016 ]
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Great deal to drive my seperates! [ Kurt  Aug 22, 2016 ]
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I have had amazing experiences with jl audio. Best sound for the money in my opinion [ Tristan  Jul 25, 2016 ]
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Good performance reveiws and great price [ PHILLIP  Jul 13, 2016 ]
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High-quality unit, for best sound at the price. [ D  Jun 25, 2016 ]
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brand [ Michael  May 13, 2016 ]
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Great brand and good power for the price! [ LUCAS  Mar 06, 2016 ]
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High quality brand and warranty, best option [ Dustin  Feb 25, 2016 ]
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10 questions already asked

Q
Could you use in a boat if it was put under console?
[ Keith  Jun 25, 2019 ]
3 answers
A
Fresh water boating should be fine and no for saltwater.
[ Ray  Jun 26, 2019 ]
A
Yes, of course you could. The question is - for how long? It isn't designed to be exposed to weather or constant moisture. There are electronics that have protection to the electronic components that will be more resistant to that type of atmosphere and that is why they are marketed as "marine use". IMHO, there is no reason to not use something that has that extra protection to perform in the conditions of "use in a boat". But in the end, yes, this amp would work in a boat..... for awhile.
[ K Henny  Jun 26, 2019 ]
A
You could though it's not "marine"rated. I've used non marine amps in boats in the past. With that said, My boat now does have all marine rated equipment in it. Amps, speakers, head unit and even marine grade wiring. 100% lasts longer.
[ Ryan  Jun 25, 2019 ]
Q
Would mounting this amp under the driver's seat cause any issues with heat dissipation?
[ DANIEL  May 27, 2019 ]
5 answers
A
No. I had two of them mounted behind the backseat of my truck and never had a problem.
[ Luis  Jun 12, 2019 ]
A
No that is where mine is mounted and works great. No issues
[ Allen  Jun 07, 2019 ]
A
I mounted one under the back seat in a '98 Jeep Grand Cherokee. I put 1/2" spacers under the feet for air circulation. I didn't have any issues.
[ John  Jun 07, 2019 ]
A
I have one mounted under the second row bench seat of my suburban and I've had no problems. There's about 2" of breathing room between the top of the amp and the bottom of the seat. Hope this helps.
[ Jeremy  Jun 07, 2019 ]
A
I have mine under the rear seat in my 2015 Silverado I've never had a heat issue I also have an Alpine amp under the seat never had a heat issue and I jam at hour or so at a time
[ Kevin  Jun 05, 2019 ]
Q
can this amp power my JBL Club 6520 (front door) and JBL Club 5000C (Rear Door) safely since they are 3 ohm speakers?
[ Daniel  Mar 12, 2017 ]
1 answer
A
Thanks for your question. For information on selecting the best amp I would recommend reaching out to an Advisor by phone (1-800-324-9695) or online chat. They will be able to help determine the differences between the amp models and help you make the best choice for your system.
[ Kenny  Mar 14, 2017 ]  Staff
Q
Why is the output voltage at each channel so different , ( starting from channel 1 going back to channel 4 ) V16.43 , 15.03, 16.43, 12.72?? That's playing at peak level for clipping. Both adjustments are set to the exact same, 16.43 is what I should be seeing...
[ Squire C.  Dec 07, 2016 ]
1 answer
A
If you purchased the product from Crutchfield, feel free to contact our Tech Support team. Our toll-free Tech Support number is printed on your invoice, and is also available under the "My Orders" tab in the "My Account" section of our website. If you did not purchase the unit from Crutchfield, then you may want to contact the manufacturer. You can also post your question in our forums: http://community.crutchfield.com. Or try our online support center: http://crutchfield.custhelp.com/app/answers/list/kw/.
[ Jeff  Dec 13, 2016 ]  Staff
Q
Also, how does one go about stripping 4 gauge wire?
[ The_Twon7  Jul 10, 2016 ]
5 answers
A
A single edge razor blade or a good sharp pocketknife!
[ Jay  Jul 12, 2016 ]
A
Find out the appropriate strip-back by lining up the wire to the terminal and make a line with a sharpie or score the wire. Then, use wire strippers or shears to lightly score the outer coating. Afterwards, pry and twist with your hand to remove the score. It should not take must force, and if it does score the wire more. Very simple process that has a small learning curve. Good luck.
[ SANDRA  Jul 11, 2016 ]
A
To be honest I use a razor blade and roll it through the sheathing being careful not to cut the copper strands.
[ ryan  Jul 11, 2016 ]
A
I just used a new razor blade and stripped the wire by cutting around the plastic/rubber shielding and used pliers to separate the plastic/rubber shielding off the end.
[ Derek  Jul 11, 2016 ]
A
Carefully
[ Mason  Jul 11, 2016 ]
Q
Can I use mini ANL 40 A fuse for the power wire?
[ The_Twon7  Jul 10, 2016 ]
3 answers
A
Yes you can. I actually used a circuit breaker in mine. You can use a mini fuse though as long as the wire gauge will feed into the holder
[ Richard  Aug 24, 2016 ]
A
A 40 amp fuse would be the recommended size Jl audio states in the owner's manual for that model amp. It doesn't matter if it's a mini ANL fuse or a AGU fuse.
[ JOHN  Jul 11, 2016 ]
A
you "can" use any wire you want. However, the wire holder fits up to a 2 gauge cable. Smaller cable will limit how much power your amp will be able to output.
[ Charles  Jul 11, 2016 ]
Q
Will this Amp fit in a Harley Davidson Street Glide Batwing fairing?
[ Justin  Feb 11, 2016 ]
3 answers
A
May be yes .. this is a very small foot print 4 channel amp available. Sounds good too. I have it on my Toyota Highlander 2015
[ Ramaswamy Reddy Pappula  Feb 12, 2016 ]
A
dunno. its relatively compact, but we talkin full size models. look into models known for being compact before you drop your paycheck. and i dont even know what a fairy batwing hd glider is, dude.
[ CAROL  Feb 12, 2016 ]
A
I am no authority on bikes, but, I believe this would be a bit of a stretch for that application.
[ Jay  Feb 12, 2016 ]
Q
Can this amp successfully power the Focal R-165s2 pair and a JL 10W0v3-4?
[ Jayson  Jun 02, 2015 ]
4 answers
A
Yes it should be perfect if you run the sub bridged off the rear channel and the focals off the front two channels. Hope this helps.
[ EARL A  Jun 04, 2015 ]
A
It should work fine... it's gonna be 70W per channel for the speakers and 200W for the Subwoofer.
[ IVAN  Jun 03, 2015 ]
A
This is the best amp for you & jl audio sub and focal sp
[ ANTONIO  Jun 03, 2015 ]
A
The speakers for sure. My sub is v2 not v3-4 so I'm not 100 percent sure.
[ Zach  Jun 03, 2015 ]
Q
Would this amp be able to power my sub and front speakers?
[ Zach  May 27, 2015 ]
1 answer
A
Thanks for your question. For information on selecting the best amp for your subs I would recommend reaching out to an Advisor by phone (1-800-324-9695) or online chat. They will be able to help determine the differences between the amp models and help you make the best choice for your system.
[ Krissy  May 28, 2015 ]  Staff
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