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Polk Audio MM521

5.25" 2-way Mobile Monitor Series Coaxial Speakers (Marine Certified)

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• Peak Power: 200W
• RMS Power: 90W
• 2-way Marine Certified Coaxial Speakers
• Woven glass composite cone woofer
• Butyl rubber surround for a smoother response
• 1" Silk/Polymer composite swivel tweeter
• Klippel optimized components for distortion-free sound

Learn more about the mm521

Good news and a little bad...

This item has been discontinued

But you may be interested in the newest model that's available.

mm522 thumbnail

Polk Audio MM522 - MM1 Series 5.25" Coaxial Speakers

OUR PRICE: $179.00

View item

Product Highlights


• Peak Power: 200W
• RMS Power: 90W
• 2-way Marine Certified Coaxial Speakers
• Woven glass composite cone woofer
• Butyl rubber surround for a smoother response
• 1" Silk/Polymer composite swivel tweeter
• Klippel optimized components for distortion-free sound

Description


Polk Audio brand icon

Authorized dealer

Will fit most 6x9" and 5x7"/6x8" locations,
with appropriate speaker adapter. Click "Related Items" Tab.

MM Series Superior Performance

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.

General Features

  • 5-1/4" 2-way MM Series Marine Certified Coaxial Speakers
  • Power Handling:
    • Peak: 400 watts per pair / 200 watts each
    • RMS: 180 watts per pair / 90 watts each
  • Woven glass composite cone woofer
  • Butyl rubber surround for a smoother response
  • 1" Silk/Polymer composite swivel tweeter
  • Klippel optimized components for distortion-free sound
  • 2.7 ohms impedance
  • 25mm Large diameter voice coil increase reliability
  • Carbon composite basket
  • Neodymium magnet structure for more power
  • Top-mount depth: 2-1/2"
  • Authorized Internet Dealer
  • 1-year Manufacturer's Warranty

Priced Per Pair

Important Note: Polk Audio specifies the nominal impedance of these speakers to be 2.7 ohms. The product box states the impedance to be 4 ohms and the speaker magnet shows 2 ohms, this has been confirmed by Polk Audio to be an incorrect specification. The product manual is correct in stating the nominal impedance of the MM series of speakers to be 2.7 ohms.

Product history:

Polk Audio MM 522 thumbnail
(newest, current model)
Polk Audio MM521 thumbnail
(previous model, replaced by Polk Audio MM522 - MM1 Series 5.25" Coaxial Speakers)

Specifications & Details


Speaker Specifications
Series
Polk MM Series
Priced Per
Pair
Speaker Size
5-1/4"
Design
2-way Coaxial
Tweeter Design
Dome
Tweeter Composition
Silk-Polymer Composite
Woofer Composition
Woven Glass Fiber
Woofer Surround
Butyl Rubber
Peak Power Handling
200 watts
RMS Power Handling
90 watts
Sensitivity
92 dB
Frequency Response
50 - 25000 Hz
Impedance (Per Voice Coil)
2.7
Top-Mount Depth (Mounting Depth)
2-1/2"
Cutout Dimensions
4-11/16 x 4-11/16 
General specifications
Speaker Grilles
Yes
Warranty and Return Policy
Parts Warranty Duration
1 year
Labor Warranty Duration
1 year
Warranty Provider
Manufacturer

Item Details


Manufacturer:

Model Number:

MM521

Weight:

4.00lbs

Internal SKU:

mm521

Internal Product ID:

17948

Product and How-to Videos


Customer Ratings & Reviews



5 star
81%
4 star
19%
3 star
0%
2 star
0%
1 star
0%



Durability
4.7
Value
4.7
Features
4.9
Design
4.9
Usability
4.8

Customer Reviews

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Great sounding speaker

Overall this speaker has a nice warm sound that gets better and better. I have only had these for a week and they get better bass extension, although it isnt completely needed because I have a sub. I purchased these the 6.5 components, and the 6x9 polks as well they sound great together. I have a 12 inch kicker L7 solobaric and these speakers keep up the bass doesnt over power them.

Pros Great customer service and quick shipping clean sound, with crisp not overall bright highs perfect sounding.

Cons: none really they sound great

By michael on April 21, 2009

68

found this helpful.

Polk MM521

I put these in my 2006 Harley Davidson Electra Glide Classic running the stock radio w/o an amp. They are a huge improvement over stock, and have amazing clarity and bass. They do get louder with use. I had to ziptie the crossovers to the fairing supports, which was no problem. I had to remove the little speaker covers, but the speakers look cool. I've washed the bike and they've been wet several times with no issues. I may try a small amp with them for more sound and clarity at speed! Highly recommend!

By RJW on November 17, 2010

65

found this helpful.

Polk Audio MM521 Speakers

I have used many brand marine stereo speakers and these are by far the best sounding speakers that I have used. Have installed about 300 stereos in golf carts and now this is the only speaker that I use.

By UniqueCarts on May 30, 2014

64

found this helpful.

MM521 = Great speakers.

I have these speakers in the fairing on my motorcycle. I have not heard better sounding 5-1/4" or smaller speakers. They play loud and clear, with great highs, and surprisingly good bass. They far surpass the stock speakers. Plus, they are waterproof.

By nunyo on August 9, 2010

67

found this helpful.

Great Speakers!

I have to say I received great customer service. I ordered speakers for my 09 HD Street glide. They installed perfectly and sound great, so much better than the stock speakers. I would recommend these speakers to anyone.

By George on October 5, 2014

61

found this helpful.

Great sound and lightweight!

I purchased two pairs of these speakers and the sound is phenomenal. I bought them for a 2 seat roadster with a very loud cabin and they have done very well on only head unit power. As a plus, they're very lightweight but sturdy. I'd highly recommend them.

By Ryan on January 21, 2012

61

found this helpful.

pretty damm goof

Very tight sound, awsome looking speaker as well. Good bass level from such a small speaker.

By sanjaystuart on May 21, 2009

59

found this helpful.

MM521

This product is the standard everybody is trying to match. Great stuff

By Sipowits on January 13, 2015

58

found this helpful.

Polk is it

Awesome speakers for my topless Jeep, got rained on several times and NO problem.

By Paul on January 20, 2012

59

found this helpful.

Polk Audio MM521

Works Great, I have had these installed for more than 6 months. Even though they have the correct size for a Plymouth Voyager, they are a little too tall. I got them mounted, but not recommended for this minivan...they sound spectacular though!

By WKahler on April 28, 2011

59

found this helpful.

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