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MTX JackHammer JH805

5-channel car amplifier — 37.5 watts x 4 at 4 ohms + 500 watts x 1 at 2 ohms

10 Reviews

Item # 236JH805

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Our take on the MTX JackHammer JH805

The JackHammer Series by MTX offers just what its name implies — aggressive styling with plenty of hard-hitting power, so your system will look great and sound even better. The chrome detailing and powder-coated steel chassis with vented bumper guards provide exceptional durability, while the MTX logo lets people know you're packing serious power.

The JackHammer Series by MTX offers just what its name implies — aggressive styling with plenty of hard-hitting power, so your system will look great and sound even better. The chrome detailing and powder-coated steel chassis with vented bumper guards provide exceptional durability, while the MTX logo lets people know you're packing serious power.

The JH805 5-channel amplifier can power your entire system, delivering 37.5 watts RMS at 4 ohms to your front and rear speakers, plus up to 500 watts RMS to a subwoofer. Patented MTX technologies process and amplify your signal without wasting energy and creating harmful levels of heat.

Active Fan Cooling speeds up the internal fan as you turn your volume up, so more cool air reaches the inner workings as power demands increase. Variable filters help you match the signal output to your speakers, and a bass boost lets you control the "boom" in your sound.

Product Highlights:

  • 5-channel car amplifier
  • 37.5 watts RMS x 4 at 4 ohms + 250 watts RMS x 1 at 4 ohms
  • 75 watts RMS x 4 at 2 ohms + 500 watts RMS x 1 at 2 ohms
  • 150 watts RMS x 2 bridged at 4 ohms + 250 watts RMS x 1 at 4 ohms (500 watts RMS x 1 at 2 ohms)
  • frequency response: 20-200 Hz
  • variable front high pass filter (40-5,000 Hz, 12 db/octave)
  • variable rear high-pass (40-8,000 Hz, 12 dB/octave) and low-pass filter (40-5,000 Hz, 12 dB/octave)
  • variable subsonic filter (40-200 Hz, 12 db/octave)
  • bass boost (12 dB at 40 Hz)
  • Active Fan Cooling with automatic variable fan speed
  • Smart Engage turns on amp when signal arrives through the speaker-level inputs
  • CEA-2006 compliant
  • preamp and speaker-level inputs
  • fuse rating: 30A x 3
  • 4-gauge power and ground leads recommended — wiring and hardware not included with amplifier
  • 17-3/16"W x 2-3/8"H x 9-1/4"D
  • warranty: 1 year
  • Our 60-day money-back guarantee

What's in the Box:

  • 5-Channel amplifier with three 30A ATO fuses inserted into chassis
  • Bass knob
  • 16.5' Bass knob cable with RJ-11 connectors on each end
  • Four 24" Speaker level to RCA adapters (each have on RCA connector on one end and bare tinned wire on other end)
  • 2 Plastic jack stands
  • 2 Screws
  • Hex-key
  • MTX Warranty Statement/Wiring diagram
  • Amplifier Performance Certificate

MTX JackHammer JH805 Reviews

Average Customer Review(s):

(10 Reviews)

Good amp.

BWX from Upstate NY on 1/2/2013

Crutchfield Customer Review (What's this?)

I did have a couple problems, but it all worked out in the end and this amp ends up being inexpensive, powerful, and sounds great. The first one I got that was part of an order which included an entire car stereo looked almost as if it had been used, sent back, reconditioned, and then sold "as new" by MTX. Crutchfield confirmed it was "new" from MTX and I believe them. I think it was just sent out from MTX with a cleaned up used case or something. It had a stripped out Phillips head screw on the bottom, and it looked dirty, and as if it had been wiped down with a dirty damp cloth, and had scuffs all over it. I paid for new, so I sent it back to Crutchfield and they sent me out a new one. After installing my new stereo (Pioneer AVH-P3300BT DVD H.U., Kicker Solo Classic 10" Dual 4-Ohm sub, SO BB10-50S Single 10" Sealed Box .54 cu.ft., and previously installed Polk db 651s speakers, etc...) everything was perfect. Then the second day, the remote to the MTX amp started acting up, and quit working. Turned out it was the wire leading to the amp, so after I got that replaced by Crutchfield, it all was perfect again. Then after a about 6 months, the amp stopped turning itself off with the car. I-(and MTX) checked everything, it was the amp at fault. It still worked great besides that. I just got the repaired amp back from MTX- they replaced the board because these are out of production. So after all that, the amp sounds even better than the first one did, and was a great deal.

Pros: Powerful subwoofer amp. Lots of adjust-ability, subwoofer remote included in price, not extra $ like a lot of Sub/5-channel amps. I am bridging the 4 channel amp to two, 4ohm channels for front left and front right door speakers. This provids plenty of clean power to those speakers, which sound great. I tried all 4 channels running all 4 door speakers at 4ohms and I wasn't as impressed so I bridged it and run just front door speakers and they sound 100 times better. I'll run rears off HU.

Cons: I think the QC department at MTX needs re-training or something. The remote cable wasn't their fault, but the first amp looking "used" was, and the second amp partially failing was too. The repaired amp with the new internals sounds amazing though, even better than the first one- a little less distortion, so maybe there was something else wrong with that one besides the shut-off issue. MTX did repair it, but I had to pay shipping one way that was $26. Still I am happy with outcome.


Jose M from Bayamon,P.R. on 11/22/2012

Crutchfield Customer Review (What's this?)

I like this amp

Pros: 5 channels of power

Cons: None

MTX JackHammer JH805

kevin from reno on 6/11/2012

Crutchfield Customer Review (What's this?)

Installed correctly, had engine noise and started to smell like burning eletronics, herd large thump from woofer; that was the sound of amp blowing woofer, returned for JL Auido amp no problems. you by a cheap amp u get cheap results

Pros: looks pretty thats about it

Cons: do not buy, spend the extra money and get a JL Auido amp

Ok but...

Jb from California on 5/26/2012

Crutchfield Customer Review (What's this?)

Worked great for a month then it just died.

Pros: Nice, powerfully, perfect or any setup? Seems well made

Cons: Died pretty quick.

MTX JackHammer JH805

Anonymous from Jay fl. on 5/17/2012

Great amp for the money I just got one for under 300. That's a deal its clean strong and has all the crossovers and boosts you will need.


Cons: Alot of wiring on one side of amp it can make it tricky to get the hook up to look clean

Quit Working

Tim from CA on 4/10/2012

Crutchfield Customer Review (What's this?)

Worked great for about five months. It was powering two 6X9's and a high performance JL sub. Hit a pothole and quit working. I have went through everything including using a voltmeter to all connections and fuses. Of course the manufacturers warrant was only good for 90 days since I installed it myself. If you buy this amplifier do yourself a favor and also purchase the extended warranty.

Pros: Worked good for five months

Cons: Quit working when my truck hit a pothole.

Great Amp

Tom from Jacksonville, Fla on 4/4/2012

Crutchfield Customer Review (What's this?)

This is a great amp. I installed ths amp in my reg. cab S10 i have it powering my 6&1/2 door speakers and my pioneer premier dvc 12"sub it hits very hard but doesnt over power my sound. now i just have to upgrade my old pioneer head unit and dash speakers and ill be set. maybe add my other sub in a blow through boxin my bed lol

Pros: easy install and easy to fig out settings never even gets warm with constant high volume rocking

Cons: none yet works great

MTX Jackhammer JH805

Frank from NJ on 3/26/2012

Crutchfield Customer Review (What's this?)

Very nice amp for the money. Decent power and very clear sound. Compact enough to mount just about anywhere. I'm using it with Kicker speakers and a JL10w6 in my 2004 Toyota Tacoma X-Cab.

Pros: Price and size.

Cons: The blue LED on the remote bass control is incredibly annoying at night. Instead of back lighting the knob, it acts like a laser beam that lights up the whole cab. I fixed the problem by just blacking the LED out with a sharpie.

MTX JackHammer JH805

JFaster08 from Ocean City, MD on 3/13/2012

Crutchfield Customer Review (What's this?)

Love this amp, perfect power and performance for the little space i have in my truck. I've always went alpine but for the price and power of this 5 Channel amp, it just can't be beat. It runs my alpine type R component speakers and 12" alpine type R subwoofer with ease and style. The other good thing was the exceptional service i got with receiving the shipment fast. I even received the directions for a spefic layout for my vehicle which came in handy when installing the amp. Not only do i love this product but Crutchfield in general. It is a great friendly company with fast exceptional service. I would recommend this amp to a friend and i will be buying from crutchfield in the future

Pros: Boom for your $ (Literally), Compact Size,Power,Bass Controller included

Cons: Bass Boost Controller has a blue L.E.D. that is almost blinding at night best to put near the floor

MTX JackHammer JH805

Cameron from Baltimore MD on 12/10/2011

Crutchfield Customer Review (What's this?)

i would definitely recommend this to anyone trying to save space and or money!

Pros: ive had this amp for about 2 months now and i love it. it powers my 2 sets of Boston Acoustics SE85 speakers great and gives plenty enough power to make my Sound Ordnance B-17 subwoofer sound perfect

Cons: when the subwoofer is turned up all the way on songs with heavy bass there is a nasty odor coming from the amp, i dont know if this is the amp itself or if its because its mounted in a confined space, never-the-less if it werent for that itd be a full 5 stars!


Hands-on research

Product Research



CEA-2006 Compliant: CEA-2006 is a new system of testing and measurement methods for mobile audio amplifiers. This voluntary standard advocates a uniform method for determining an amplifier's RMS power output and signal-to-noise ratio. The criteria for measuring power uses a DC input voltage of 14.4 volts and the RMS power output is measured into a 4-ohm load, with 1% or less Total Harmonic Distortion (THD) plus noise, and at a frequency range of 20 Hz to 20,000 Hz when applicable. Signal-to-Noise ratio is measured in weighted absolute decibels (dBA) at a reference of 1 watt into 4 ohms. CEA-2006 allows consumers to compare car amplifiers and receivers on an equal basis. The MTX Jack Hammer JH805 under CEA-2006 regulations is rated at 37.5 Watts RMS x 4 channels with a 75dBA signal to noise ratio + 250 Watts RMX x 1 channel with a 70dBA signal to noise ratio.

5-Channel Amplifier: The MTX Jack Hammer JH805 is a 5-channel amplifier designed to power your front and rear full-range speakers as well as your subwoofer(s). The JH805 can be configured for 5-way or 3-way operation.

2-Ohm Stable: The MTX 5-channel amplifier is capable of handling load impedances down to 2-ohms. The amplifier is rated at 75 Watts RMS x 4 channels + 500 Watts RMS x 1 channel in 2 ohms with 1% THD. 

Bridgeable: The MTX JH805's Front (1/2) and Rear channels (3/4) can be bridged down to two channels to output 150 Watts x 2-channels at 4 ohm.

AB/Class D Amplifier Design: The Jack Hammer JH805 features an AB class amplifier for its front and rear channels and a Class D amplifier for it subwoofer channel.

  • Pure N-Channel Mosfet Class A/B Design: The Jack Hammer's front and rear channel amplifier utilizes Pure N-Channel Mosfet technology for more linear speaker control, enhanced signal-to-noise ratio and more power. This design lets the audio signal travel through fewer parts making the output stage of the amplifier more efficient and giving you more usable power from the amp.
  • Class-D Design: The JH805's subwoofer channel is powered by a Class D mono-block amplifier, which uses digital switching to amplify audio signals. This design results in high efficiency and less heat.

Active Fan Cooling: Rather than weighing the amplifier down with heavy aluminum heat sinks, the Jack Hammer amplifier is cooled using a variable speed internal fan. The increasing output of the amplifier engages the fan to automatically increase its speed allowing more cool air to enter the amplifier. This keeps the amplifier performing at its peak level longer and prevents the amplifier from going into thermal shutdown due to overheating. The fan will automatically slow down when the amplifier's output is decreased.

Protection Circuits: The JH805 provides Thermal and Overload protection with LED indicators.

Stackable: You can stack up to three Jack Hammer amplifier on top of one another using the supplied "JackStands".


Crossovers: The Jack Hammer JH805 is equipped with various crossovers for all 5-channels.

  • Front Channel Crossovers: The Front channels (1/2) feature a variable 12dB/octave high-pass crossover which can be set between 40 and 8,000Hz. This crossover can be turned off for full-range operation.
  • Rear Channel Crossovers: The Rear channels (2/3) feature variable 12dB/octave high-pass and low-pass crossover settings. The high-pass crossover can be set between 40Hz and 8kHz, while the low-pass crossover can be set between 40Hz and 5kHz. There is also and Band-Pass setting for midrange or midbass speakers. In addition the Rear channels can be run at full-range.
  • Subwoofer Channel Crossovers: The Subwoofer channel features a variable 24dB/octave low-pass crossover which can be set between 40 and 200Hz.

Bass Boost: The bass boost is adjustable from 0-12dB at 40Hz.

Sub-Sonic Filter: This amp features an adjustable 20 to 50Hz, 12dB/octave Sub-Sonic Filter. Ultra-low frequencies that cannot be reproduced by a subwoofer do not become sound but become unnecessary oscillations, which affect sound by causing distortion. These frequencies also waste amplifier power and can cause damage to speakers. Setting the Sub-Sonic Filter between 20Hz to 50Hz cuts the frequencies below the respective frequency to improve the reproduction performance of the speakers by eliminating harmful distortion.

Remote Bass Knob: The MTX JH805 comes supplied with a wired remote bass knob which allows you to adjust the bass output of the amplifier's subwoofer channel. The bass knob is designed to be mounted underneath your vehicle's dash within arm's length so its easily accessible to the driver. The bass knob connects to the amplifier using the supplied 16.5' RJ-11 cord. The wired remote bass knob measures 2.655" wide x 0.755" tall x 1.955" deep.


Power/Ground/Turn-On Connections: The JH805 features set-screw terminals for the Power, Ground and Remote turn-on lead. The Power and Ground terminals will accommodate up to an 4 AWG wire, while the Remote turn-on lead will accept up to a 16 AWG wire.

RCA Inputs: The three pair of RCA type line-level inputs have gain (Input Sensitivity) control. The Input Sensitivity control will accept an input signal of 250mV to 5.0 Volts.

Smart-Engage Speaker Level Input: The Jack Hammer JH805 comes with a set of speaker level input harnesses. This feature makes it easier to add an amplifier to a factory radio or to a receiver with no preamp outputs. When using the speaker-level inputs, the amp automatically turns on when it senses signal from the head unit, eliminating the need for a remote turn-on connection. In many cases, this feature will allow you to install the amplifier without removing your radio.

Speaker Connections: The amplifier is equipped with six pairs of speaker terminals for connection of 4 pairs of speakers and a subwoofer(s). The amplifier uses set-screw speaker terminals which will accommodate 12 to 8 AWG speaker wire.

EBC: RJ-11 connection for connecting the supplied wire remote bass knob.

Fuse: The amplifier is equipped with three 30-AMP fuses.

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.