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JL Audio Slash 300/4v3

4-channel car amplifier — 75 watts RMS x 4

9 Reviews


Our take on the JL Audio Slash 300/4v3

JL Audio's 300/4v3 4-channel amplifier puts out 75 watts RMS per channel to your speakers, so you'll enjoy powerful, moving music in you car. You can also configure this amp to 2-channel mode and run two subwoofers with 150 watts RMS each. JL Audio's patented Class-AB amp circuitry delivers exceptional, natural sound with extremely low distortion. The cast aluminum heatsink dissipates heat quickly, so the amp will run reliably for a long, long time.

Pure power for your system

JL Audio's 300/4v3 4-channel amplifier puts out 75 watts RMS per channel to your speakers, so you'll enjoy powerful, moving music in you car. You can also configure this amp to 2-channel mode and run two subwoofers with 150 watts RMS each. JL Audio's patented Class-AB amp circuitry delivers exceptional, natural sound with extremely low distortion. The cast aluminum heatsink dissipates heat quickly, so the amp will run reliably for a long, long time.

Consistent power for performance you can count on

This Slash v3 amplifier isn't just powerful, it's smart. As your car system's voltage fluctuates while you drive, the Regulated, Intelligent Power Supply™ system maintains steady, consistent power at any impedance between 1.5 and 4 ohms and at any voltage between 11 and 14.4 volts. You'll get all the power, all the time, even with a wide range of speaker combinations.

Minimize external noise

The 300/4v3 uses "differential-balanced inputs" to isolate the signal's ground from the chassis ground, reducing noise and making this Slash v3 amplifier compatible with almost any system, including most factory radios. Variable high- and low-pass filters give you precise level of control needed to maximize the performance of your speakers or subwoofers.

Product Highlights:

  • 4-channel car amplifier
  • 75 watts RMS x 4 at 1.5 to 4 ohms
  • 150 watts RMS x 2 at 3 to 8 ohms
  • Regulated, Intelligent Power Supply system
  • differential-balanced inputs
  • variable high- and low-pass filters (50-5000 Hz, 12 or 24 dB/octave)
  • Absolute Symmetry™ Class-AB amplifier design
  • MOSFET power and output stages
  • preamp and speaker-level inputs (speaker-level input requires two optional adapter packs)
  • 4-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
  • 13-7/16"W x 2-1/4"H x 10"D
  • warranty: 2 years
  • Our 60-day money-back guarantee

This amp puts out plenty of clean power and makes my Focal components sound their best. I particularly liked how easy it was to adjust the gain using a voltmeter since it took the guesswork out of the process.

Nicholas, Buchanan, NY

What's in the Box:

  • Four channel amplifier
  • 2.5mm Allen wrench
  • Owner's manual

JL Audio Slash 300/4v3 Reviews

Average Customer Review(s):

(9 Reviews)

JL Audio Slash 300/4v3

Nicholas from Buchanan, NY on 7/14/2017

Crutchfield Customer Review (What's this?)

This amp puts out plenty of clean power and makes my Focal components sound their best. I particularly liked how easy it was to adjust the gain using a voltmeter since it took the guesswork out of the process.

Pros: Ease of setup, looks, sound & power!


Great amp

Mark from Chesnee, SC on 4/2/2017

Crutchfield Customer Review (What's this?)

Jl audio makes great amps. My first one lasted 15 years. I hope this one will be just as good. I had a few questions about this amp and Crutchfield's customer service was great, they answered every question I had. Definitely recommend jl audio products and Crutchfield is the place to buy them.

Pros: Quality product, great prices,

Cons: None

Better than HD

P from Boston, MA on 2/18/2017

Crutchfield Customer Review (What's this?)

Have this amp powering two sets of Focal 165v comps does an amazing job providing clean powerful sound.

Pros: No noise when audio off, RIPS technology

Cons: Slightly big which is expected with a class a/b

Very clean sound at higher volume

FasterBug from Los Angeles, CA on 5/2/2016

Crutchfield Customer Review (What's this?)

I replaced an old Kenwood 4-channel amo with this one. WOW, the difference is amazing. The sound is so clean, I'm very happy I spent a little more money for the quality of this amp.

Pros: Clean, multiple configuration choices.

Cons: Can't think of any.

Worth the money

Mike E from Ashland, KY on 4/20/2016

Crutchfield Customer Review (What's this?)

This amp is everything I hoped it would be. I push it hard and it barely gets warm to the touch. The sound is crystal clear.

Pros: Great sound.


Clean Power

RockR from Cedar Hill, Tx on 10/2/2014

Crutchfield Customer Review (What's this?)

I've been a fan of JL for quite some time. This was an upgrade from my V1 300/4. I have been no less than blown away with how clean and powerful these amps are.

Pros: Clean, quality workmanship, very versatile.

Cons: N/A

Excellent amp

Michael from PA on 5/29/2014

Crutchfield Customer Review (What's this?)

This amp has unbelievable sound. I hear details in music my previous Eclipse amp simply did not reproduce. No distortion at all and truly reference grade sound. However, this amp seems to have unusually powerful midbass, I had to tweak down my PEQ settings accordingly and I highly recommend using dynamat liberally.

Pros: Great sound, no audible distortion

Cons: Expensive

Another awesome product from JL Audio!!!!

Mike from South Jersey on 3/13/2014

I picked this amp up to upgrade my older JL Audio Slash 300/4 v1. I've been using JL Audio products in my Vehicle for about 10 years now. I'm using this amp to push a pair of Focal Integration speakers (temporary until I get the funds to get a pair of Focal K2's) and temporarily pushing a JL 10W7v2 with channels 3 and 4 bridged. This amp not only puts out amazing clear full range sound to the component speakers, but It is easily pushing that 10W7v2 without distortion or compromise despite the fact that it's only sending 150W to the sub!! Obviously this is temporary until I pick up the new 600/1v3 Slash which is gonna replace my 500/1v1 Slash which just gave out on me after 10 years! This amp is a beast and looks awsome with the powder black case. I couldn't be happier with this amp and I highly recommend this amp and any other JL product. You can't go wrong!!!

Pros: Awesome sound and top notch Circuitry JL amps output at least what they are rated at unlike most other brands Good price for what you get, Definitely worth every penny and more!!!

Cons: None

JL Amp rocks!

Dave from Indianapolis on 9/15/2013

Crutchfield Customer Review (What's this?)

Great amp. Worth the price. You always get what you pay for with JL Audio. Building a competition system. This amp drives 4 Alpine door speakers in a 2010 Highlander. Mounted underneath front passenger seat.

Pros: Rocks. No issues thus far.

Cons: None at this time.


Hands-on research

Product Research



Four-Channel Full-Range Amplifier: The JL Audio 300/4v3 is a class A/B four-channel, full-range amplifier, rated at 75 watts RMS x 4-channels into a 1.5Ω to 4Ω load, measured from 20 Hz to 20kHz with a power supply voltage of 11 to 14.5 Volts. The signal-to-noise-ratio is 108.5 dB and total harmonic distortion is 0.03%, both at rated power from 20 Hz to 20kHz. The amplifier can also be bridged to output 150 watts RMS x 2-channels into 3Ω to 8Ω loads.

R.I.P.S. (Regulated Intelligent Power Supply): The JL Audio R.I.P.S. system ensures consistent power delivery over a wide range of battery voltages and load impedances, providing the rated power output at any impedance from 1.5Ω to 4Ω and at any vehicle voltage from 11V to 14.5V.

  • Regulated Power Supply: The power supply adjusts to maintain the amplifier's rated power output and low distortion operation over a wide range of vehicle voltages (11V-14.5V), so the amplifier's output remains stable in real-world car audio situations.
  • Intelligent Power Supply: An intelligent circuit monitors output current to optimize the amplifier's output power over a wide range of load impedances (1.5Ω to 4Ω). The R.I.P.S. System detects the actual load impedance, rather than relying on often inaccurate assumptions based on a speaker's rated impedance, and adjusts output rail voltages to deliver consistent output.

RealSink Heat Management: The large cast alloy heat sink's vertical fins are very effective at dissipating heat from the amplifier via convection and radiation. This design is achieved through extensive finite-element analysis, resulting in an amplifier that stays cool under demanding conditions. As an added cosmetic benefit, the cast-aluminum end-caps replicate half of a heat sink fin so that when two or more amplifiers are mounted end-to-end, you get a seamless custom look.

Advanced Rollback Protection: If a Slash v3 amplifier should ever reach an unsafe temperature, the Advanced Rollback Protection circuit reduces power until the amplifier cools down, without turning the music off completely.

Absolute Symmetry Class A/B Circuitry: The 300/4v3 amplifier benefits from patented Absolute Symmetry Class A/B Circuitry technology to maintain high fidelity with low distortion over a wide range of load impedances. The circuit employs identical N-Channel MOSFET transistors to push and pull the speaker with true buffering from the load impedance.

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 adding line output converters, you can directly connect most factory radios 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, eliminating any voltage sensitivity between that terminal and ground, and greatly reducing the incidence of alternator whine in a typical car audio installation.

Protection Circuitry with Status Indicator Lights: There are three status indicator lights on the top of the amplifier:

  • Power (Green): lights green to indicate the amplifier is on and operating normally
  • Thermal (Red): lights to indicate the amplifier has exceeded its safe operating temperature, putting the amplifier into a shelf-protection mode, which reduces the power output of the amplifier; the red light will turn off and the amplifier will return to full-power operating mode when the internal temperature returns to a safe level
  • Low Ohm (Amber): lights to indicate the impedance of the speaker load is lower than optimum; when this light is on, a protection circuit engages and reduces the power output of the amplifier; the amber indicator will also light when a short-circuit is detected in the speaker wiring

Note: The only condition that will shut down the 300/4v3 completely is the battery voltage dropping below 10 volts.


Gain: The front and rear amplifier sections have independent gain controls, continuously variable from 200mV to 8V (200mV to 2V with the Input Voltage switch in the Low position, 800mV to 8V with the Input Voltage switch in the High position). The amplifier's R.I.P.S. feature also offers an easy way to optimize the gain setting. Because the amplifier will always deliver the same amount of power within its operational impedance range and supply voltage range, the maximum, unclipped output is predictable. This makes setting the gain level of the amplifier via the input sensitivity control very simple. All you need is digital AC voltmeter (item number 142TK12V, sold separately) and a test disc with a sine wave test tone recorded at 0 dB reference level in the frequency range to be amplified (item number 503CD104, sold separately).

Active Crossover: The front and rear amplifier sections also have independent crossover controls:

  • Filter Mode: three position switch; Off (full-range), LP(low-pass), or HP (high-pass)
  • Frequency: rotary dial, variable from 50 Hz to 500 Hz or 500 Hz to 5 kHz (depending on the frequency range switch)
  • Frequency Range: two position switch to specify the crossover frequency dial range; 50 Hz to 500 Hz (x1) or 500 Hz to 5 kHz (x10)
  • Filter Slope: two position switch to specify the crossover slope; 12dB/octave (Butterworth) or 24dB/octave (Linkwitz-Riley)

Input Mode: The amplifier's input mode switch allows you to choose between 4-channel and 2-channel mode. The 4-channel mode requires that two pair of RCA inputs be connected to the amplifier's front and rear inputs, while the 2-channel mode only requires one pair connected to the front inputs. Not front to rear fading is possible in the 2-channel mode.


Power and Ground: The amplifier's set-screw power and ground connections accept up to 4-gauge wire. JL Audio recommends 4-gauge for any power wire longer than six feet (8-gauge is acceptable if the power wire is shorter than six feet).

Note: The Amplifier is not equipped with an internal fuse. An external 40-amp fuse (not included) must be installed on the power wire. If the system has only this amp and a wiring kit is used that includes a fuse with a value other than 40-amps, the original should be replaced with a 40-amp fuse.

Remote Turn-On: The set-screw remote terminal accepts up to 8-gauge wire.

Speaker Outputs: The four pair of set-screw speaker terminals accept up to 8-gauge speaker wire.

Signal Input: The amplifier features two pair of stereo RCA inputs (front and rear). If no line level signal is available, you will need two speaker wire to RCA adaptors (item number 136XDCLR2S, sold separately) to connect the amplifier to the source unit via speaker wires.

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

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 verify what’s in the box, 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.

Q & A

Customer Q&A

Crutchfield asked  
Why did you buy this?

JL Audio reputation and it was exactly what I needed. The class a/b will give cleaner sound![ titanium man  Jun 29, 2017 ]
My old amp stopped working. It was the older style 300/4v3. It worked for 11 years. It worked great for years[ Mark Worth  Apr 25, 2017 ]
Power and excellent review. I am totally pleased with this amp. Expensive, but very clean sound from 2 pairs of components.[ Eric  May 20, 2016 ]