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Polk Audio MM1240

425W 12" Mobile Monitor Series Single 4 ohm Marine Certified Car Subwoofer

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Marine Certified: Also great for car installs!

List price $279.95

You Save: $109.96 (39.28%)


with warranty

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Arrives by Thursday, Apr. 23 to zip 07095

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Bundled Savings with this Product


Frequently Bought Together - 10% off Sound Dampening

Save 10% on an NVX trunk kit that contains 20 sq. ft. of quality sound dampening material. This material quiets vibrations, stops rattles, and increases the subwoofer SPL.




Polk Audio MM1240



10% OFF



Special Price $53.99 ($59.99 if purchased separately)


• Eliminates Road Noise
• Quiets Vibrations
• Stops Rattles • Increases SPL
• Reduces Heat
• Simple To Install
• Easy To Form Aluminum
• Four Step Peel and Stick Installation
• Five 18" x 32" Pieces

(Offer 1 of 1)

Combined Total Price


You Save $6.00

The Mobile Monitor Series by Polk Audio is the result of 3 years of research and development. The series uses high quality materials and the newest loudspeaker technology to bring the listener an unforgettable experience. The best part about the MM Series is the affordable price.

Product Features

  • 12" Single 4 ohm Mobile Monitor Series Subwoofer
  • Power Handling:
    • Peak: 800 watts
    • RMS: 425 watts
  • Impedance: Single 4 Ohm
  • Polymer woofer cone
  • Butyl rubber surround
  • Carbon Composite Basket is very lightweight and will not flex during use
  • Marine Certified
  • Nickel plated heavy duty terminals can be used with speaker wire up to 8 gauge or two twisted pairs of 12 gauge
  • Klippel Distortion Analyzer results in the best possible performance at any listening level
  • 2" High temperature copper voice coil
  • Also found as: MM-1240, MM1240svc, MM-1240svc
  • Frequency response: 22-200 Hz
  • Sensitivity: 92 dB
  • db Series Subwoofer Grill Available
  • 1-year warranty

Product History:

Polk Audio MM1240 thumbnail
(newest, current model)
Polk Audio MM2124 thumbnail
(previous model, replaced by Polk Audio MM1240)

Subwoofer Specifications

Subwoofer Series
Each subwoofer manufactured is part of a series. This is the name of the subwoofer's series.
Mobile Monitor (Polk Audio)
Subwoofer Size
Refers to the diameter of the subwoofer, measured in inches.
Peak Power Handling
Peak power handling refers to the amount of power a speaker can handle during a brief musical burst. The RMS power range figure is a much more reliable rating for determining the speaker's power requirements. The Peak power handling specification is typically rated per speaker unless otherwise noted.
850 watts
RMS Power Handling
The RMS power is the amount of power the speaker requires to operate safely and properly. RMS Power Handling refers to the amount of power a speaker can handle on a continuous basis. We recommend powering your speakers or subwoofer with 80%-120% of its recommended RMS rating. The RMS power handling specification is typically rated per speaker unless otherwise noted.
425 watts
Voice Coil(s)
Dual voice coil subs have more wiring flexibility than single voice coils subs; however, single voice coil subwoofers provide easier hookup options for wiring multiple subwoofers in parallel or series. You may also run a dual voice coil (DVC) sub in parallel, series, or combination. A quad voice coil has four voice coils and is equal to two dual voice coil subwoofers as far as wiring goes.
Impedance (Per Voice Coil)
The load value (in ohms) that the speakers present to the amplifier per voice coil - the amount of resistance to the current flow. This is a key specification as subs wired in parallel or low impedances can create problems with your amplifier and potentially void all warranties. We encourage you to ask our support department prior to purchase if you do not understand which impedance level will suit your application best.
4 ohms
Voice Coil Diameter
Diameter of voice coil, usually measured in inches.
Frequency Response
The range of frequencies the speaker will reproduce (lowest frequency to the highest). Bigger is better, meaning the wider the range, the better. The optimal range is 20 - 20,000 Hz (which is the range of human hearing).
22 - 200 Hz
An efficiency or sensitivity rating tells you how effectively a speaker converts power into sound. The higher the number, the more efficient the speaker and the louder it will play with the same input power. An efficient speaker helps you maximize your available power. Most sensitivity ratings measure the speaker's output with 1 watt of input, 1 meter from the speaker. Some speakers' sensitivity is measured with 2.83 volts of input, instead of 1 watt.
Efficiency (1w/1m) is not an accurate indicator of a subwoofer's output capability and should not be used as a comparison to other speakers or subwoofers to determine which one is "louder".
92 dB
Xmax (millimeters)
Typically measured in millimeters, the Xmax value is the measure of a speaker cone's maximum excursion in one direction while maintaining a linear behavior.
25 mm
Subwoofer Design
This is the design of the subwoofer or the opening of the subwoofer enclosure. Each design has it's own benefits, whether it is a square, circle, or oval.

Round/Circle: This is the typical and common subwoofer design. They have a round cone and are a circle in design.

Square: These woofers are able to achieve a greater cone area in a smaller space. Because of the greater surface area, some square subwoofers will be louder than a round subwoofer of the same size.

Round / Circle
Main Cone Color
This is the color of the speaker's or subwoofer's cone.
Woofer Composition
Lightweight woofer cone materials are essential for efficient operation. Poly cones produce exceptional sound and are sturdy against various changes in temperature. Paper cones are very efficient, and when treated for moisture resistance, will perform at a high level. Poly refers to polypropylene, which is thermoplastic or fibers that are polymers of propylene. IMPP refers to injection molded polypropylene, a commonly used process and material in speakers.
Polymer/Mica Composite
Woofer Surround
A speakers surround is part of the suspension system. The surround protects the cone and prevents it from being displaced as it flexes out from the basket. It is usually made of a durable material like treated foam or rubber in order to withstand the strenuous job of producing bass frequencies.
Butyl Rubber
Magnet Structure
Defines the overall structure of the subwoofers magnet.
Subwoofer Grille
Most subwoofers are able to accommodate a universal grille; however, some subs include a grille and others have a specific, optional grille available for purchase separately. If "yes", then the subwoofer includes a grille. If "optional (sold separately)" the matching grille will need to be purchased in addition to the sub.
Re-Cone Kit Available
Some higher end subwoofers have replaceable cone assemblies. In case of a blown woofer, a recone kit allows for a simple replacement, as opposed to purchasing an entire new subwoofer.

Recommended Enclosure Specifications

Recommended Enclosure Type
This is the recommended type of enclosure that the subwoofer should be installed into. Some subwoofers are specially designed for particular enclosures.

Sealed: These enclosures completely enclose the air inside the box. These boxes produce a tight bass.

Ported/Vented: These enclosures have a slot of air to escape from the box. The result is a sound that has more "boom".

Bandpass: These are a combination of both sealed and ported enclosures. They can be very efficient, but require tuning for the best response.

Minimum Sealed Box Volume
This value indicates the minimum sealed box volume that the manufacturer recommends for the subwoofer. The volume is typically displayed in cubic feet.
.88 cubic feet
Optimum Sealed Box Volume
This value indicates the ideal sealed box volume that the manufacturer recommends for the subwoofer. The volume is typically displayed in cubic feet.
Maximum Sealed Box Volume
This value indicates the maximum sealed box volume that the manufacturer recommends for the subwoofer. The volume is typically displayed in cubic feet.
.88 cubic feet
Optimum Ported Box Volume
This value indicates the ideal ported box volume that the manufacturer recommends for the subwoofer. The volume is typically displayed in cubic feet.
Top-Mount Depth
The depth when installed on top of the mounting surface. Measured from the bottom of the speaker's magnet to the bottom of the mounting holes on the rim of the speaker.
Cutout Diameter
The actual diameter of the hole you will need to cut out if you are creating a new mounting location for this speaker, or if you are mounting a subwoofer in a box.
Shallow Mount Installation
This means that the subwoofer/speaker is designed to be installed in areas that do not have a lot of space. Shallow mount subwoofers are typically found under a seat or behind the seat in some trucks.

Shallow mount speakers will typically have a mounting depth of 2" or less, while shallow mount subwoofers will typically have a mounting depth of 3" or less.


Electromechanical Parameters

Free-Air Resonance (Fs)
The free-air resonance frequency of the subwoofer, measured in Hz. At this frequency the weight of the moving parts is perfectly balanced with the subwoofers suspension system.
Equivalent Compliance (Vas)
This is the amount of air that has the same stiffness as the subwoofers suspension. The greater the rating, the lower the stiffness and larger recommended enclosure. It is measured in Liters.
Total Speaker Q Value (Qts)
This is the subwoofers relative damping (Q) at the resonance frequency (Fs), including all dimensionless losses. Essentially, a high Qts value (closer to 1.0) means the subwoofer is great for sealed enclosures and a low Qts value (closer to 0) means the woofer is great in vented enclosures. A Qts of around 0.45 means the woofer will work decently in either enclosure type.
Electrical Q Value (Qes)
The subwoofers relative damping (Q) at the resonance frequency (Fs), including electrical losses. Also called the mechanical damping of the subwoofer. The unitless measurement usually varies from 0.5 10.
Electrical Resistance of Voice Coil (Re)
Amount of DC resistance of the subwoofer when measured with an ohm meter. Typically, this will read less than the impedance rating of the subwoofer.
Mechanical Q Value (Qms)
This is the subwoofers relative damping (Q) at the resonance frequency (Fs), including mechanical losses. Also called the mechanical damping of the subwoofer. This unitless measurement usually varies from 0.5 10.
Efficiency Bandwidth Product (EBP)
This number represents the trade off between having an efficient woofer and one with a wide bandwidth. To calculate this number, take the Fs and divide it by the Qes. If the number is below 50, the woofer is designed for a sealed enclosure only. If it's between 50-100 it can be used in either. Lastly, if it's greater than 100 it's designed for vented enclosures.

Specials with this Item

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Warranty and Return Policy

Parts Warranty Duration
1 year
Labor Warranty Duration
1 year
Warranty Provider

Summary of Customer Ratings & Reviews

Rating Distribution

5 Star
4 Star
3 Star
2 Star
1 Star

Average Attribution Rating


Lincoln ne

The Best Sound

June 21, 2011

I bought these about 6 months ago and boy do they sound good. I did research on many name brand subs before finally deciding on these and I am very satisfied. The price was good but nothing can beat the base sounds that they put out, not even the price. I will never get any other subs but Polk. If you want nice sounding subs go with another brand but if you want the best sounding subs then pick up a pair of Polk Audio subs. From a man that's been listenning to bass all his life, you will be happy.

7 of 9 found this helpful

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the thump is back

November 14, 2011

I was using 2 jbl gt5 s12 sub's in my toyota innova, read about this sub on various sites believe me it deserves 5 star rating. It can out perform my 2 jbl subs with a ease, it sounds clean and can go very deep even with sealed enclosure. It is a only sub that can perform good with less power. My search for the best sub is over with this sub.

5 of 7 found this helpful

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St. Paul, MN


September 17, 2013

These subs are incredible. I paired them with a 5000 watt (at 1 ohm) amp and they kick like a mother. I put 2 of them in an angled double 12" sealed sub box and they sound amazing. I love the sound they make in the sealed box, it is incredibly tight. They hit like no other sub i have heard. Every time i give people rides they are overwhelmed by them, they can easily get louder than your ears can take it you want haha. I see no cons to these subs, incredibly well built, i all most hated to put them in the box because they look so good all around. Pair them with polk mid woofers and tweeters and you will not be disappointed!

5 of 8 found this helpful

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Baltimore, MD

the shallow speaker that could -- (rock your world)

July 24, 2012

installed 2 of those in chevy sierra 1500 extended under rear seat matched with kicker zx750.1 under 2 ohm load and while i normaly don't waste my time reviewing anything ----- those 2 deserve review enought for me to actualy sit down and type (i hate TYPING)

dont get me wrong they are NOT as good as SR series (no longer manufactured) but not very far behind ----- they handle anything from rap to rock right through some of the heaviest base hitting electronic !
you set your amp gain and eq right and you can and will switch betwen music genere without touching any controls in your head unit or adjusting eq (some older ROCK might require a little base boost)

if you are looking for SQ with some awesome pressure look no further they are not going to win against DD's or other 75 lb monstrocity designed for nothing but monster pressure under very narrow frequency band!!!

but any main stream (good Brand SUB) is going to have to work extra HARD to hold their own against MM series and it's a losing battle

i've compared them to several others and no JL, RF, RA, KICKER, MA is comming close to versatility of sound being reproduced (some get slightly louder but at much higher price bracket)

the recesed magnet is an awesome idea !!

dont forget your poly fill (10-20 oz. bag pet chamber) and take POLK.s advide and make your Bafle 1" thick MDF your ears will apreciate this very much and so will your amp !!!

P.S. i've tried those 2 powered by Hifonics Brutus BRZ-1200.1D and the efect was just as astounding !!!!!! and just my observation is the those subs do better in wel designed sealed enclosure of at least .7 to 1.2 cu ft per chamber ! - although i've installed a single mm 1240 under HIFONICS BRZ 1200.1D in sealed .62 cu ft (in my 2012 Toyota Yaris) in 4 ohm configuration with amp mounted upside down above my doughnut spare and absolutely love the result The sub POUNDS very hard and amp under 4 OHM load NEVER gets warm on normal weather and warm to touch durring the summer on the hotest of days !!!!

hope this helps some of you in making the decision to moove towards one of the best speaker out there from a manufacturer who is bent on SQ since they started in AUDIO !!!!!

5 of 9 found this helpful

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Altoona, IA

loud and great sound

March 10, 2015

we love the sound that this put out its crazy and it dont distort or crackle

1 of 3 found this helpful

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The best money can buy

January 11, 2014

first of all this is the best sub money can buy, highly recommended for those who love music, specially some deep bass.
Pros: can handle all types of music, has good SPL potential, highly reliable, don't need much power even a small amp will do, looks cool, needs little space as compare to other subs, one is equal to 2 normal subs.
cons: please provide a grill
i am a SPL fan, I was using two jbl subs for a while, but the space and power requirement was a major concern.
i started searching for a sub which can deliver deep bass. After searching on various websites, i finally come across this sub, read reviews on various websites.
I bought one sub in a sealed box, believe me my first impression was "this is the sub i was waiting for", it took my breath away, it is a complete sub. one sub is equal to 2 jbl subs, great sub. All my friends were amazed by the pressure level and sound quality of this sub.
My system is updated on regular bases but this is the only thing which remains unchanged almost for three years. Finally if you love music this is a sub for you.

3 of 7 found this helpful

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Towson, MD

Love It!

August 7, 2009

I have one of these in my dodge durango running on a AP1200 Profile Amp and it hits hard and loud not to mention it also can hit bass in every range. I highly recommend this sub along with any of polk's products, thats all i have and they havent let me down whatsoever

5 of 11 found this helpful

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Rohnert Park Ca.

Polk Audio MM1240

August 21, 2013

i have a Pioneer head unit with 4 Kenwood 6x9s, a 1000 watts 5 channel and a 1200 watt mono amp. this MM1240 has great deep sound and hits hard. Go out and buy it you may like it to.

2 of 6 found this helpful

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Santa Fe, NM


May 29, 2009

This sub is awesome! i bought two of them and they hit hard now i am gonna have to buy Dyanamat from sonic cuz they rattle the whole car! awesome sub in my opinion!

2 of 8 found this helpful

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Accessory Tools and Products

Accessories added

Single 12" Subwoofer Angled Truck or Hatchback Box Enclosure

CARB Compliant, 5/8" MDF Shallow Sub Enclosure Lined with Polyfil.

Your Price $29.99

12" SingleHatchback Style Small Sealed Subwoofer Enclosure

CARB Compliant, 3/4" MDF Dual Hatchback Style Sealed Enclosure w/ Premium Carpeted Finish

Your Price $42.95

12" Medium Sealed Subwoofer Enclosure

CARB Compliant, 3/4" MDF Sealed Enclosure Lined with Premium Carpeted Finish

Your Price $47.95

NVX 25 ft. of True Spec 12 Gauge Speaker Wire

100% OFC wire with EnvyFlex metallic jacket insulates and protects against damage from extreme conditions.

Your Price $39.99

25 ft. of Streetwires 12 Gauge Speaker Cable

You'll need speaker wire to hook up that new subwoofer!

Your Price $44.95

Belva 23 ft. of 12 Gauge Speaker Wire

Ultra-flexible PVC blended jacket for easy installation.

Your Price $14.99

20 Square Feet of Sound Dampening Material

NVX Sound dampening is thicker than competitors, eliminates rattles and gives you bigger bass!

Your Price $59.99

Stinger Sound Dampening Trunk Kit

Stinger's Roadkill sound dampening series is sure to kill unwanted road noise and rattles! Enough sound dampening for your whole trunk!

Your Price $69.99

12 oz. Can of Adhesive Spray

Spray adhesive used for adhering carpet to subwoofer boxes without bubbles.

Your Price $6.99

40" x 15 Ft Piece of Premium Un-Backed Automotive Trim Carpet

Durable design for long life-span, available in many colors and shades.

Your Price $39.99

Gold Plated Dual Terminal Banana Plug Connector

Enables an expandable, secure connection accepting up to 8 gauge wire.

Your Price $1.99

2" Universal, Professional Heavy Duty Roller for Sound Damping/Dampening

Universal rubber roller to make it easy to install sound dampening.

Your Price $7.99

Car Stereo and Speaker Installation Tool Kit

Includes Test Light, Crimp/Splice Tool, Multi-bit Screwdriver and more.

Your Price $16.99

Xscorpion 9-Piece Nylon Plastic Pry and Chisel Tool Set

Easily removes dash/trims, door clips, panels and pins, rubber grommets and vehicle emblems.

Your Price $14.99

Cordless Multi-Functional Heat Tool Soldering Iron Kit

Continuous working lock allows you to work without holding down trigger.

Your Price $79.99

4 Ft of 1/4" Thick Black Heat Shrink Tubing

Provides abrasion resistance and added protection for your cables.

Your Price $3.99

1mm All Purpose Solder

Solder is all purpose for use on most projects where solder is needed.

Your Price $8.99

12" Protective Waffle Subwoofer Grille

Keep your subwoofer looking amazing while keeping it safe.

Your Price $4.99

Scosche SPL Meter

Monitor the noise level of your new car audio system with this SPL meter measuring from 60-135 dB.

Your Price $21.99

1 Polk Audio MM1240 Subwoofer

Mono Amp

2 Channel Amp - Bridged

2 Polk Audio MM1240 Subwoofers

Mono Amp

2 Channel Amp

4 Channel Amp - Bridged

3 Polk Audio MM1240 Subwoofers

4 Channel Amp

4 Polk Audio MM1240 Subwoofers

Mono Amp

Mono Amp - Option 1

2 Channel Amp

2 Channel Amp - Bridged

4 Channel Amp

Items we think you might want
MM1240DVC thumbnail
Polk Audio MM1240DVC

• 850W Peak
• 425W RMS
• Polymer woofer cone
• Butyl rubber surround
• Carbon Composite Basket
• Marine Certified
• Klippel Distortion Analyzer

Your Price $169.99

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Product Summary


Model Number






Internal SKU


Internal Product ID


Sonic Electronix Wiring Guide

Wiring Diagram Legend

Warning: The image depicted shows the resistance change when wiring multiple subwoofer terminals. Please refer to your subwoofer's owner's manual for the proper wiring of its terminals. Sonic Electronix, Inc. is not responsible for damage caused to your audio system or vehicle due to improper installation. Please call tech support at 1-877-289-7664 if you require additional assistance.

Product Name: Polk Audio MM1240