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Alpine MRX-M55

Mono subwoofer amplifier — 550 watts RMS x 1 at 2 ohms

26 Reviews | 2 questions - 9 answers

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Item # 500MRXM55

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Our take on the Alpine MRX-M55

Alpine's X-Power MRX-M55 mono amplifier uses the latest amp technology to play your music loud and clean without taking up much space. And this amp employs some of the same circuitry developed for Alpine's top-of-the-line PDX digital amps, so it'll bring exceptional sound to almost any ride.

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Digital technology that sounds perfect

Alpine's X-Power MRX-M55 mono amplifier uses the latest amp technology to play your music loud and clean without taking up much space. And this amp employs some of the same circuitry developed for Alpine's top-of-the-line PDX digital amps, so it'll bring exceptional sound to almost any ride.

Big power for big bass

The MRX-M55 puts out up to 550 watts RMS to your subwoofer system, so you can fill your listening space with plenty of bass. And it'll even operate safely with a 1-ohm load, making it useful in a variety of sub system installations. Onboard low-pass and subsonic filters let you get the best sound out of your setup, while a bass boost helps to fatten up the sound if you need it.

Keep the music playing

A power management system optimizes the amp's performance and keeps the music playing, even when you're pushing it hot and hard for a long time. Speaker-level inputs with an automatic turn-on feature simplify system hook-up.

MRX-M55 control panel

Confused about impedance? Check out our article on matching subs and amps.

One of the best amps i have ever owned .

Daniel, Electra TX

Featured Video:

What's in the Box:

  • Mono amplifier with two 30A fuses installed
  • Left plastic terminal cover
  • Right plastic terminal cover
  • 4 Terminal cover screws (M3 x 10mm)
  • 4 Self-tapping screws (M4 x 20mm)
  • 2.5mm Allen wrench
  • 7" Speaker-level input harness
  • Owner's Manual (Eng/ Fren/ Span)
  • Warranty sheet
  • Online registration card
  • Alpine Verification Certificate

Product Highlights:

  • mono subwoofer car amplifier
  • 350 watts RMS x 1 at 4 ohms (550 watts RMS x 1 at 2 ohms)
  • 400 watts RMS x 1 at 1 ohm
  • CEA-2006 compliant
  • variable low-pass filter (50-400 Hz, 24 dB/octave)
  • variable bass boost (0-12 dB at 50 Hz)
  • variable subsonic filter (5-30 Hz, 24 dB/octave)
  • optional remote level control (RUX-KNOB)
  • Class D amp with MOSFET power supply
  • preamp and speaker-level inputs
  • preamp outputs
  • fuse rating: 30A x 2
  • 8-gauge power and ground leads recommended — wiring and hardware not included with amplifier
  • 9-15/16"W x 2-5/16"H x 9-1/16"D
  • warranty: 1 year
  • Our 60-day money-back guarantee

Alpine MRX-M55 Reviews

Average Customer Review(s):

(26 Reviews)
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Hands-on research

Product Research



MRX Amplifier Design: Class-D amplifiers boast higher efficiency, produce less heat, and draw less current than traditional Class-AB amps. The MRX series benefits from the technology trickledown from Alpine's more expensive PDX amps, including Direct FET final outputs, thermal management processor, 6-Layer Glass Epoxy PC Board; combining to create a high-end sound quality without the bulky heat sinks required by most amps in this power class.

STAR Topology: Alpine's unique STAR (Signal Transit for Accurate Response) Circuit PCB design provides a single common ground for all amp sub-blocks, preventing ground interference and minimizing internal noise.

Power Management Processor: The multi-stage Power Management Processor continuously monitors component temperatures throughout the amplifier and decreases power output if anything gets too hot. When playing music under heavy loads for long periods, the circuit automatically reduces power output slightly at first, and then further in a second stage if necessary. This two stage approach provides an interruption free listening experience.

CEA 2006 Compliant: The MRX-M55's power ratings are measured according to the Consumer Electronics Association CEA-2006 standards. These standards allow you to accurately compare the rated power output of all CEA 2006-compliant amplifiers, even different brands. Manufacturers who adhere to the standards can display the CEA 2006 logo on their products and packaging. The power output is measured from 20 Hz to 400 Hz using a 14.4 volt power supply with no more than 0.01% THD+N:

  • 4-ohm: 350 watts
  • 2-ohm: 550 watts
  • 1-ohm: 400 watts

Signal-to-Noise: When measured under CEA-2006 conditions (reference 1 watt into a 4-ohm load) the signal to noise ratio is 90 dBA. Measured at the rated power output S/N is 114 dB.

Verification Certificate: The amplifier comes with a certificate that lists the RMS power output measured from that specific amplifier. It also lists the model number, serial number, test date, and the test conditions (voltage and impedance).

Auto Turn On: When using the speaker level inputs the X-Power amplifiers automatically turn on when voltage is detected on the signal inputs, making them an easy factory system upgrade.

Low Output Impedance: With low output impedance, the MRX-M55 outputs tightly controlled bass, with a damping Factor rated at greater than 1000.

LED: The top panel LED power indicator glows blue when the amplifier is turned on.


Gain: The MRX-M55's gain is set according to the level of the incoming signal. The line-level input gain setting is continuously variable from 100 mV to 4.0V; the speaker-level input gain setting is continuously variable from 250 mV to 10.0V.

Crossover: The low-pass crossover point is continuously variable from 50 to 400 Hz and the slope is 24 dB/oct; the crossover cannot be bypassed.

Subsonic Filter: The amp also has a 24 dB/oct subsonic filter, continuously variable from 5 to 30 Hz.

Bass EQ: Bass boost can be applied to the subwoofer output; it's variable from 0 to +12 dB and centered at 50 Hz.


Power/Ground/Remote: The MRX-M55 features set-screw terminals for the Power, Ground and Remote Turn-on inputs. The Power and Ground terminals will accommodate up to 4 gauge wire (Alpine recommends 4 gauge for cable runs over 3'), the Remote Turn-on terminal will accept up to 8 gauge wire.

Speaker Output: The speaker outputs terminal is also set-screw terminals and will accept up to 8 gauge wire.

Line Input/Output: Line level RCA is the preferred input connection. The full range stereo line output allows easily adding another amp without running a second set of cables.

Speaker Level Input: Use the included speaker level input harnesses if the connected radio has no preamp outputs.

Fuses: The amp is protected by two chassis mounted 30-amp ATO fuses.

Remote Bass Control (optional): Alpine's RUXKNOB wired remote (sold separately), connects to the amp's RJ-25 Remote Bass Control jack, and offers control of the subwoofer output level from the front of your vehicle. The linear attenuation can be adjusted from 0 to -20dB.

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Q & A

Customer Q&A

2 questions already asked

I bought an 8 gauge amp kit locally, I think it was a Rockford Fosgate kit. They price matched it to online so it wasn't too expensive. As long as you stick with a name brand, you'll be fine. [ Charles  Aug 09, 2014 ]
I would use at least a 8 gauge or bigger power and ground wire, i used 4 guage. And yes you are gonna want a better quality install kit, because lower quality kits can cause unwanted noise in your system. You really need to pay attention to the RCA cables that go from the head unit to the amp that is where you are going to want a higher quality cable. Make sure to use at least a 12 guage wire from your amp to speakers, anything smaller can possibly cause your amp to shut down . By the way you should be very pleased with this amp, i have it pushing a single 12" alpine type R and it sound very good, almost hits harder than the 2 kicker 12" i use to have. Anyways good luck and i hope this helps [ Kevin  Aug 04, 2014 ]
4 gauge power wire with big in line fuse,4 gauge ground ,make sure the ground wire is as short as possible,depending on the speaker 8 to 12 gauge for the speaker wire, remote turn-on you can use a 16 gauge is fine :-) [ GREG  Aug 04, 2014 ]
Your wire gauge depends upon the length of wire you plan on using. For instance a short run (couple feet)you could get away with 8 or 6 gauge. A longer run (several feet) would require bigger wire like 4 or 2 gauge. The bigger the wire the easier it is for the amp to obtain the power it needs and the amp with also run cooler and more efficient. Stay away from cheap install kits, often times the wire they supply does not measure what it's labled. [ matthew  Aug 04, 2014 ]
I bought a 4 gauge wiring kit to go with it, and I'd works perfectly fine. The 4 gauge allowed plenty of power to flow through the amp with no distortion at all. [ Caleb  Aug 04, 2014 ]
Hi David E - we probably don't know each other but our vendor asked me to answer your questions so for what it's worth here you go: Q: What gauage wire? A: That depends. How far is the +12V source? In a typical vehicle the run is less than 20 feet so assuming the only device connected to the power lead is this amplifier then the size Alpine recommends is fine. I just happened to have enough 8g. on hand and installed this model in a Tacoma under the rear jump seats. Q: Kits vs SQ? A: Copper is copper so as long as the wire is the correct gauge there should not be a significant difference from one brand to the next. Kits usually include RCA type signal cables so this is where price can make a difference. Stay away from the budget kits that use little or no shielding and flimsy RCA connectors. You didn't ask but I'll offer this as advice for your installation. Grounding is more important than most folks understand. Use at least the same gauge wire as the battery lead and plan the mounting location out to keep the ground lead to a reasonable minimum - one or two feet if possible. Larger wires need proper crimp tools to attach the right type of connetor like a ring lug and then make sure to bolt the lug to bare metal and cover the area with silicone or spray paint to prevent rust. Hope this helps. Scott [ Scott  Aug 04, 2014 ]
4 gauge or 8 gauge , 4 gauge I believe it runs better and make sure you have a really really good ground, a lot of kits are the same just make sure you get the better gauge! [ BRAD  Aug 04, 2014 ]
I used 4 ga for power, 8 ga for ground, and 12 ga for my subwoofer. Everything works and sounds great. The power wire was bought as a kit with an inline fuse and RCA cables. [ MARK W  Aug 04, 2014 ]

1 answer Hi, I have an amp and a sub 1) the question is - how to wire them? Original thought was to run amp as 4 ohm @ 350W to 4 ohm sub @ 300W, but after some reading it is my understanding that only way to wire them is either at 2 or 8 ohm, parallel or series, 2) @ 2ohm the amp will output 550W to 300W sub, is it possible to tune it down, turn gain down or something? 3) if above doesn't work, would amp output 550W when head unit is turned all the way up? So if I turn it up half way, would it cause the amp to output ~275W ? 4) what will happen if I wire them as 8ohm? Thank you, Andrei. [ Andrei  Apr 08, 2014 ]

If you purchased the product from Crutchfield, feel free to contact our Tech Support team. They can walk you through the install. 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: Or try our online support center: [ Krissy  Apr 08, 2014 ]  Staff