Polk Audio MM651UM

6.5" 2-Way Ultra Marine Certified Mobile Monitor MM Series Coaxial Car Speakers

Product videos

• Peak Power: 400W
• RMS Power: 200W
• 1" Silk Composite Soft Dome Tweeter
• Mounting Depth: 2-5/16"
• Woven Glass Composite Woofer Cone
• 4 Ohms Impedance
• Sensitivity: 92dB

Learn more about the mm651um-silver

Good news and a little bad...

This item has been discontinued

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

mm651um-oeblack thumbnail

Polk Audio MM651UM Special Edition Black

OUR PRICE: $135.99

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Product Highlights

• Peak Power: 400W
• RMS Power: 200W
• 1" Silk Composite Soft Dome Tweeter
• Mounting Depth: 2-5/16"
• Woven Glass Composite Woofer Cone
• 4 Ohms Impedance
• Sensitivity: 92dB


Polk Audio

Authorized dealer

Buy the Special Edition MM651UM

Available Now - CLICK HERE

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

MM Series Special Edition Marine Speakers

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. These special edition marine speakers have a superior performance at an affordable price.

MM Series Ultra Marine Speakers

Tested to meet Marine Standards:

The MM Series speakers are considered an ultra-marine because they have passed the 600 hours of salt fog and UV testing of the ASTM international B117-03 and D4329-99 standards. Stainless steel heavy duty input terminals and mounting hardware are used to last and not corrode in marine environments. The completely sealed front design prevents water intrusion that would otherwise damage the speaker.

MM Series Built-on Grille with Tweeter

Built-on Grille with Tweeter:

The MM Series speakers have a built-on grille that includes a tweeter mount. This eliminates the tweeter "stalk" that is normally used for the tweeter mount so the front can be completely sealed to prevent any water intrusion. These features and attention to detail are the reason why Polk speakers are offered by Correct Craft on their award-winning Nautiques ski and wakeboarding boats.

General Features:

  • 6-1/2" Ultra Marine Mobile Monitor MM Series 2-Way Marine Speakers
  • Power Handling:
    • Peak: 400 watts per pair / 200 watts each
    • RMS: 200 watts per pair / 100 watts each
  • Recommended power range: 15 - 110 Watts RMS per channel
  • Completely sealed front designed for protection against water instrusion
  • Meets ASTM international B117-03 and D4329-99 marine standards
  • Passed 600 hours of salt fog and UV testing to meet international marine standards
  • Woven glass composite cone woofer
  • Butyl rubber surround
  • 1" Soft dome weather resistant dynamic balance tweeter
  • Built-on grille with tweeter mount
  • Sealed crossover assembly is built into the back of the magnet
  • Klippel optimized components for the strongest performance even at high listening levels
  • 4 ohm impedance
  • 1-3/8" (30mm) Large diameter voice coil
  • Neodymium magnet structure
  • Sealed crossover assembly built into back of magnet
  • Stainless steel heavy duty input terminals and mounting hardware
  • Salt, fog and UV Resistant
  • Top-mount depth: 2-5/8"
  • Authorized Internet Dealer
  • 1-year Manufacturer's Warranty

Priced Per Pair

Product history:

Polk Audio MM651UM-Black thumbnail
(newest, current model)
Polk Audio MM651UM thumbnail
(previous model, replaced by Polk Audio MM651UM Special Edition Black)

Specifications & Details

Speaker Specifications
Polk MM Series
Priced Per
Speaker Size
2-way Coaxial
Tweeter Design
Tweeter Composition
Silk-Polymer Composite
Woofer Composition
Woven Glass Fiber
Woofer Surround
Butyl Rubber
Peak Power Handling
200 watts
RMS Power Handling
100 watts
Total RMS Per Pair/Set
Total RMS Per Pair/Set
92 dB
Frequency Response
40 - 25000 Hz
Impedance (Per Voice Coil)
4 ohms
Voice Coil Diameter
Magnet weight
Magnet Type
Top-Mount Depth (Mounting Depth)
Bottom-Mount Depth
Cutout Dimensions
5-1/16 x 5-1/16 
Number of Speakers
CTA-2031 Compliant
General specifications
Marine Certified
Hi-Res Certified
Speaker Grilles
Includes Damping Kit
What is in the box?
WITB: Speakers
Other Accessory #1
Other Accessory #2
Other Accessory #3
Other Accessory #4
Other Accessory #5
Other Accessory #6
Warranty and Return Policy
Parts Warranty Duration
1 year
Labor Warranty Duration
1 year
Warranty Provider

Item Details


Model Number:




Internal SKU:


Internal Product ID:


Product and How-to Videos

  • How To Test Speaker Polarity | Tips & Demo | Car Audio 101
  • Replace your Car Speakers and Upgrade to Better Sound | Sonic Electronix

Customer Ratings & Reviews

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Awesome Speakers!

I ordered these to install on the swim deck of my AR230 Yamaha boat. They sound amazing! Water rushes over them and drowns them every single time the boat stops and they have never skipped a beat. No disappointments.

By Scott on January 11, 2012


found this helpful.

Great Sound, Smooth and Balance, Durable, Candy for the Ears!

These are great sounding speakers! I am very picky on audio and visual. I used these speakers on the outside of my toyhauler. The sound is superb with great bass and clear highs. Overall tonal balance is natural and smooth. People and friends tell me how nice the music sounds and I have to agree! I really enjoy listening to music in camp as long as the surrounding area is quiet. These speakers would also fit a boat nicely as well. I would even put them in a car but you are overpaying for the Ultra Marine qualities. I wash my RV after every trip and the speakers hold up well to water spray(I try and avoid direct hose streams). They also hold up well to wind as the speakers see freeway speeds while towing. If you need a durable speaker with awesome sound quality then look no further! If you are strictly into sound quality competition then you probably need separates which would provide minimal gains in SQ. I have them hooked up to a Soundstream Rubicon amp but they sounded impressive playing off the Pioneer Premier head unit as well! I highly recommend them for a marine environment or exposure to outdoors.

By TheMofo on March 8, 2010


found this helpful.

Pok Audio MM651UM Marine Speakers

I purchased these as upgrades to the stock speakers in my boat. These are exposed to the elements on every outing. I am actually overdriving these speakers with more power than recommended so as to have the headroom for a clean, undistorted sound from my amp. And these speakers handle it beautifully. They have a remarkable low end for their size and as I adjust the crossover on my amp, the speakers do not seem to have a dead spot. So much so that I have adjusted my crossover to accommodate the sweet spot of my Kickers because these Polks can handle the full range. I wish the grill offered a little more protection but it would do so at the expense of sound quality so I'm very happy with these!

By lowtones on September 17, 2013


found this helpful.

Great sound. Good value

I replaced two old speakers on my center console Carolina Skiff. They are exposed to slot of weather and hold up very well. The sound is excellent. Very deep base and no distortion. I would highly recommend them.

By Crabman on December 2, 2010


found this helpful.

Great product!!!!

These speakers are a really great buy, sound great and look great
Strongly suggestion buying these. I plan on buying another pair. The guys at Sonic Electronic were very helpful and order was received very quickly
Thanks again

By Jason on May 19, 2014


found this helpful.

Great speakers

These are true marine speakers. The silk dome tweeter keeps the treble very smooth yet detailed. The bass is better than the WetSounds speakers I compared them to. Feed them with plenty of the highest quality watts you can afford and you will be richly rewarded. At the price Sonic sells them for, this purchase is a no brainer.

By skyskier on September 12, 2010


found this helpful.

Excellent Marine Speakers

I replaced the four outside original Clarion speakers in my Sea Ray 33 foot 330 Sundancer with the Polk Audio MM651UM speakers. They fit in the existing openings and only required re-drilling for the mounting screws. The sound is excellent. I am not an audio snob but I do appreciate good quality sound and I am extremely happy with these speakers. I investigated the DXi650 model speakers and was very disappointed with the sound quality from them. I highly recommend spending the extra money on the MM series as they sound much, much better and they are completely water proof. The only negative I can find is that the speaker grill leaves much of the cone exposed. If you have young children that might poke their finger into the speaker or if the speakers will be mounted in an active area where something might puncture the speaker then that might be an issue. Otherwise, they are great. You will not be disappointed with the sound and you cannot beat Sonic Electronix price either. They are a great deal through this vendor.

By Bob on January 19, 2011


found this helpful.


I upgraded the stock radio and speakers in my boat with a pair of Polk MM651UM speakers. I chose this pair based on size, power rating to match the new stereo unit, and assumed quality. I am sure they could provide extra kick if I installed an amp but they do just fine without and I dont want to add anymore load to the electrical system. I am satisfied with the look, power, and sound that I get from these speakers, they sound great.

By gds on December 9, 2010


found this helpful.

Excellent sound and low end range

I highly recommend these speakers as they sound wonderful with a great low end punch. I bought these for my boat and will be buying 2 more pair to put in my car. Great value and incredible sound.

By Thurston, III on October 18, 2009


found this helpful.

Great quality!

These look good, and sound amazing. Add an amp to them and you'll be even more impressed.

By Boat Boy on January 3, 2012


found this helpful.


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