Skip Navigation

Polk Audio MM651

6-3/4" 2-way speakers

68 Reviews | 10 questions - 30 answers

Find what fits your vehicle


Can't find your exact vehicle?

Item # 107MM651

This item is no longer available.

Shop all 6-3/4" Speakers

New model available

Polk Audio MM 652




Our take on the Polk Audio MM651

Polk Audio continues its tradition of making brilliant-sounding speakers in stylishly designed packages — their Mobile Monitor (MM) Series speakers look great and sound even better. Each speaker utilizes an extra-strong, extra-small neodymium magnet that saves space and weight, allowing these speakers to fit into more places in more vehicles while still delivering a full sound with lots of kick. Their lightweight carbon composite frames provide strong, flex-free support for the speakers' motor assemblies.

Polk Audio continues its tradition of making brilliant-sounding speakers in stylishly designed packages — their Mobile Monitor (MM) Series speakers look great and sound even better. Each speaker utilizes an extra-strong, extra-small neodymium magnet that saves space and weight, allowing these speakers to fit into more places in more vehicles while still delivering a full sound with lots of kick. Their lightweight carbon composite frames provide strong, flex-free support for the speakers' motor assemblies.

The Polk MM651 6-3/4" speakers feature honeycomb-textured woven glass fiber composite woofer cones that respond very quickly for a clean, crisp, and powerful sound. Large voice coils — over an inch in diameter — give the speaker high power handling capability and extended reliability.

1" silk dome tweeters add a sweet high end that blends perfectly with the low notes so your music stays in harmonic balance, from the electric bass all the way on up to the cymbals. Swivel mounts on the tweeters allow you to aim the high notes to produce a superior sound stage in your car.

Important Note: These Polk speakers use a low-impedance design to pull more power safely from your car stereo or amplifier. This design is compatible with all factory and aftermarket stereos.

Note: Polk describes this model as a 6-1/2" speaker. Most manufacturers designate this same frame size as a 6-3/4" speaker. For simplicity's sake we list it as a 6-3/4" speaker.

Priced per pair

Product Highlights:

  • 6-3/4" 2-way speakers (pair)
  • woven honeycomb glass fiber composite woofer cone with butyl rubber surround
  • 1" silk composite dome tweeter with swivel mount
  • includes two external crossovers (speaker wire not included)
  • certified for marine use
  • 2.7-ohm impedance for extra power (compatible with all factory or aftermarket car stereos)
  • power range: 15-100 watts RMS (200 watts peak power)
  • frequency response: 40-25,000 Hz
  • sensitivity: 94 dB @ 1 watt
  • top-mount depth: 2-5/8"
  • warranty: 1 year
  • Our 60-day money-back guarantee

What's in the Box:

  • Two 2-way 6.75" speakers
  • 2 Grilles
  • 2 Passive crossovers (with wire attached)
  • 2 Mounting ring adapters (includes GM/Chrysler 6-3/4G)
  • 8 Hex-head screws
  • 4 Phillips-head screws
  • 8 Speed clips
  • Owner's manual
  • Product registration information sheet

Installed in my 2016 road glide with Rockford fosgate pbr300x2 amp running off factory head unit and sounds awesome, no comparison to original equipment, will be adding polks to the saddle bags next

Jim, Gray, Ga


Polk Audio MM651 Reviews

Average Customer Review(s):

(68 Reviews)

Can't wait to hear them in my car

Walter from Undisclosed on 10/2/2017

1990 Nissan 300ZX
Crutchfield Customer Review (What's this?)

A few months ago I went to local install store in northern Colorado to get some ideas for my 90 300zx tt. The installer had the Polk mm6501s up front and mm651s in rear, With two enclosed 8s in trunk. I liked them so much i have been scouring eBay and amazon on the search. Luckily I found these 651s on crutchfield at this phenomenally low price. I already bought the 6501s and just bought new kenwood head unit today, all from crutchfield. It's a complete bummer though as I'm military deployed to the Middle East for the next few months and can't rock out until next year. I will try to take pics in the fair lady of new speakers as soon as I get home to install. Thanks crutchfield. As always a little patience paid off huge. I love you guys and your awesome customer support. Don't forget your loyal troops overseas!

Pros: Smooth highs and good lows great price.

Cons: I can't get home to put them in

Polk Audio MM651

Jim from Gray, Ga on 8/24/2017

Crutchfield Customer Review (What's this?)

Installed in my 2016 road glide with Rockford fosgate pbr300x2 amp running off factory head unit and sounds awesome, no comparison to original equipment, will be adding polks to the saddle bags next

Pros: Fit well, sounds great, and marine certified

Cons: Non so far

Polk Audio MM651

Michael from Michigan on 6/5/2017

2012 Harley Davidson Street Glide
Crutchfield Customer Review (What's this?)

Excellent speakers with everything to install.

Pros: Everything in one box

Cons: Needs a little better instructions for installation

Excellent product

Matt from Klamath Falls, OR on 5/21/2017

Crutchfield Customer Review (What's this?)

Easy install! Excellent performance! They are exactly what I was looking for to install in my Surf Boat. Customer service went above and beyond to assist me in finding that perfect speaker.

Pros: Excellent performance

Cons: Attaching the crossover to fiberglass

Polk Audio MM651

Anonymous from Manchester, NH on 5/11/2017

2009 Chevrolet Silverado 2500/3500
Crutchfield Customer Review (What's this?)

High sensitivity speakers work great with stock head unit. These replaced stock speakers in a 2009 Chevy 2500HD; a known problem on these trucks is water leaking down inside the door. The old speakers were corroded and non-functioning. Hopefully the new, marine-rated MM651 speakers will last longer. I got these on sale because they've been discontinued - they were worth every penny.



Best Bang for the buck

Scott from Acworth Ga. on 5/7/2017

2008 Harley Davidson Electra Glide
Crutchfield Customer Review (What's this?)

Very crisp and clear sound in mids and highs. Very well constructed. I'm very satisfied with these speakers.

Pros: Loud and clear. Great construction.

Cons: None

Polk and Crutchfield are great

Nick from Beaver Dam, WI on 4/20/2017

Crutchfield Customer Review (What's this?)

Great speakers and great pricing as an open box item from Crutchfield!

Pros: Great speakers and pricing


Great Value, Good Sound

Steve from La Crosse, WI on 4/18/2017

Crutchfield Customer Review (What's this?)

Good sound overall, easily mountable crossover and great value for the money. Does not include mounting hardware (screws etc). Comes with ring mount adapter and grill.

Pros: Lightweight design, small crossover, clear highs, good midrange. Price and value for the money.

Cons: Tweeter and Woofer leads off the crossover could be longer. Easier to trim than to extend. No screws or hardware. Just a mounting ring and grill.

Awesome across the boatd

Steve from Melbourne Florida on 4/17/2017

2004 Ford Explorer
Crutchfield Customer Review (What's this?)

Bought them for the motorcycle. Excellent sound. Incredibly fast delivery. And a awesome price

Pros: Excellent sound, price, and delivery

Cons: None

Polk Audio MM651

kyle from TX on 4/4/2017

Crutchfield Customer Review (What's this?)

Great speakers i love them



Great sound, easy install

Dave...Paola, Ks from Paola, KS on 4/3/2017

2014 Harley Davidson Street Glide
Crutchfield Customer Review (What's this?)

i installed them on my street glide, the install was pretty easy, had to figure on how to and where to put the cross over box, but went in and installed easy...quick little adjustment on the amp and can hear me a block away....AWESOME set of speakers, will order another set when i add to lower leg fairings.



Polk Audio MM651

Anonymous from Minneapolis, MN on 3/25/2017

2004 Pontiac Grand Prix
Crutchfield Customer Review (What's this?)

Good sound, however did not come close to fitting my vehicle.



Polk Audio MM651

Carl from Manassas, VA on 3/20/2017

2017 Volkswagen Jetta
Crutchfield Customer Review (What's this?)

Great for the price to back fill rears

Pros: Great Price Easy Install

Cons: none for price point

Polk Audio MM651

Anonymous from Tn on 12/20/2016

Crutchfield Customer Review (What's this?)

You can't beat these speakers ,I've installed in the Harley Davidson and the sound is just unbeaten for the price



Polk Audio MM651

Cory from Burton, MI on 12/17/2016

2006 Harley Davidson Electra Glide
Crutchfield Customer Review (What's this?)

These speakers sound awesome in my Harley fairing. I liked them so much I bought a second pair to put in the lower fairings as well.

Pros: Sound and fit great.

Cons: None

Polk Audio MM651

Chris from Wichita, KS on 12/8/2016

2011 Harley Davidson Street Glide
Crutchfield Customer Review (What's this?)

Awesome quality speakers.



Polk Audio MM651

Anonymous from Los angeles on 11/20/2016

2015 Honda Civic EX
Crutchfield Customer Review (What's this?)

I replaced the door and rear shelf speakers on my 2015 Honda Civic with these, keeping the factory head unit. Crutchfield did not list The rear shelf location as being compatible with these speakers . But they fitted fine using the same adapter as the front door. It was not necessary to cut the plastic trim at all, however I did need to bend the sheet metal of the speaker opening slightly on both door and rear shelf to allow the new speakers to seat properly. This was easy to do with a pair of pliers and could easily be bent back if needed. The sound is much more solid and detailed with the polks. I was specifically looking to reduce the harshness in higher frequencies with the factory speakers and was somewhat satisfied with this. They are smoother but I still find I need to reduce the treble level a little . I have a powered sub in the trunk already so I did not need or notice any improvement in bass.

Pros: Fits both door and rear shelf of 2015 civic.

Cons: Still some high frequency harshness with factory head unit

Perfect for Wranglers

Jason from Detroit, MI on 11/1/2016

2013 Jeep Wrangler Unlimited
Crutchfield Customer Review (What's this?)

Fit right into my Jeep's rear sound bar with a little modification, mounted the x-overs easily too. SAC-656 adapters helped and so did some sound deadening work. waterproof upgrade speakers that fit perfect. Great. :)

Pros: fits right into my jeep's rear sound bar

Cons: some modification required

Sound is good

Danielle from Joliet,IL on 10/26/2016

Crutchfield Customer Review (What's this?)

I bought this as a gift for my boyfriends birthday and he loves them.



good sound

Heather from Mission, KS on 10/22/2016

2014 Mazda 6
Crutchfield Customer Review (What's this?)

Great Speaker for the money! I would of liked more bass, but overall they sound good and made for a good factory replacement speaker.

Pros: clean, crisp sound.

Cons: more bass would be nice.

Polk Audio MM651

Anonymous from Waupaca, WI on 10/16/2016

2008 Chevrolet Silverado
Crutchfield Customer Review (What's this?)

great sound, vey easy install, modified oem bracket to mount speaker to door. I find there is less vibration when turned up.



Polk Audio MM651

Richard from Wellford Sc on 10/5/2016

2004 Pontiac GTO
Crutchfield Customer Review (What's this?)

This speakers are awesome first I bought three pair for multiple cars and ordered 3 more you have to hear them hook up to a amp they sound great.????

Pros: Crossover work excellent

Cons: None at all

Awesome Speakers

Charles from York, PA on 9/18/2016

2011 Chevrolet Cruze
Crutchfield Customer Review (What's this?)

As always Polk makes amazing speakers. After installing these speakers they had amazing sound and fit perfectly into my Cruze.



Great sound

Mike K from LONGVIEW Tx. on 9/16/2016

Crutchfield Customer Review (What's this?)

Installed on my 2016 Road Glide. Sounds great. No distortion at any volume level.

Pros: Easy to install. Great price. Great sound.

Cons: None

Polk Audio MM651

Anonymous from Alabama on 9/13/2016

2016 Dodge Charger
Crutchfield Customer Review (What's this?)

These speakers sound great. Good clear highs, nice overall tone and good bass response. They fit perfectly and drop right in the tour pack pods of my 2014 Harley Ultra Limited. Mounted the crossovers in the tour pack with Velcro and ran the wires through the factory port. Easy peasy. Highly recommended!



Polk Audio MM651

Anonymous from Panama City, FL on 9/5/2016

2013 Chevrolet Silverado 1500
Crutchfield Customer Review (What's this?)

Awesome sounding speakers replaced factory speakers in my 2013 Chevrolet Silverado

Pros: Great sounding speakers for the money

Cons: None

Polk Audio MM651

Anonymous from coram, ny on 8/18/2016

2014 Subaru Forester
Crutchfield Customer Review (What's this?)

Handles a lot of power. Good bass and very clear mids and highs.

Pros: Great all round sound.

Cons: none

Polk Aaudio MM651 2way 6 3/4" Speakers Are Not What They Seem

SamB from Columbia, KY on 8/8/2016

Crutchfield Customer Review (What's this?)

I always look at the reviews before I buy something. I found nothing about the true size of these speakers till I received them in just 3 days (fast shipping). I thought I was getting a set of 6inches and 3/4.wrong. They measured just 5&1/4 inches. What makes me mad is poke says on there web site that they are 6 1/2" but fit where 6 3/4" speakers fit. Ok I wanted 6 3/4" speakers to get that larger filling sound of 6 3/4" speakers. The Polk mm651 two ways are a good speaker dont get me wrong but sound small witch a 5 1/4" speaker does unless they are used for low end only but as a full range speaker just dont cut it for me. That is what I like is a larger speaker. Everybodys opinion is different and that is cool. But what is not cool is you being lead to believe a product is something that is not. False advertising is something that Crutchfield is not known for. I think that they really dont know but Polk does for sure.

Pros: Good speaker for the right size car.

Cons: Only 5 1/4" when advertisied as 6 3/4". Just want people to know what they are getting for real and not what the box says.

Crutchfield response on 8/10/2016 Car speaker sizing can be one of most confusing things we deal with on a daily basis here at Crutchfield, and it helps to think of speakers in categories instead of sizes. Measuring a speaker will never yield the same number as its category, as SamB pointed out in his comment. If you look at what we consider to be a 6-1/2" speaker, you'll notice the cone size is actually just over 5", just like SamB stated. To help our customers, we decided to take the research we did on speaker locations in various vehicles and translate that into what fits from the measurements we actually take from the speakers we sell. We hoped to eliminate some of the confusion and not mislead customers. These sizes are not always indicative of what the factory speaker size was. In any event, you can find out more about identifying speaker "sizes" here. Note: Polk describes this model as a 6 1/2" speaker. Most manufacturers designate this same frame size as a 6 3/4" speaker. For simplicity's sake we list it as a 6 3/4" speaker.

Polk in my boat

Av8or from Lexington, Ky on 8/7/2016

Crutchfield Customer Review (What's this?)

Last year I put Polk speakers in my jeep and absolutely loved them. When I got my boat I wanted to upgrade the sound system in it so I did so with the Polk speakers and love them! Brit was a lot of help! Thanks again Crutchfield! Very pleased!



Polk Audio MM651

Michele H from Destin FL on 8/6/2016

Crutchfield Customer Review (What's this?)

Installed these in my 2013 GEM Low Speed Vehicle! AWSOME sound!



Harley Davidson Road Glide Ultra install

Keith from MI on 8/6/2016

Crutchfield Customer Review (What's this?)

I installed 4 of these on to a 2016 Harley FLTRU with the stock radio and no amp and they sound great. I should mention with stock exhaust because if your running with loud exhaust you may need an amp and these will handle it

Pros: They fit in the OEM location with good volume, within 3 bars of full volume with no distortion, I have never found an OEM receiver that didn't have some distortion at full volume

Cons: Not that it's a con but had to trim a small area on the rear speakers, the plastic surrounding the magnet in one spot (the lowest spot when installed) is a little thick I just cut that tab off and they fit perfect. Mounting the crossovers simply mount the fronts next to the radio and the rears in the tour pack, a little 2" Velcro goes a long way .


DAVID from CHICAGO, IL on 8/2/2016

2001 Bentley Arnage
Crutchfield Customer Review (What's this?)

I have 4 of these in the cockpit of my 2001 26' Sea Ray Sundancer with 100 watts a piece going to them. Combined with a JL W7 - I can turn my system pretty much as loud as I want with little to no distortion. I cook them all weekend long on Lake Michigan and everyone can't get over how loud, distortion free, clear, and powerful they really are. They did take some time to break in however once they were, you can turn them up to the moon and they will remain. Hate to say it, but they almost sounds as good as my JL 6.5 Components inside the cabin if not better. Buy these, for the price you won't regret it. I've been doing this audio stuff for years.

Pros: Superior clarity, loudness, with minimal distortion

Cons: Lengthy break in process. Sometimes will sound funny if they get really wet but will clear up once dry. Both a very small factor.

Polk Audio MM651

Phil VZ from Hull,Ia on 8/1/2016

2012 Harley Davidson Street Glide
Crutchfield Customer Review (What's this?)

Sound great,look like quality speaker



As always, Polk delivers

Will from Atlanta, GA on 7/31/2016

2008 Chevrolet Silverado
Crutchfield Customer Review (What's this?)

Polk is my favorite speaker brand and have them in all my cars. In my opinion Polk delivers the best sound quality of all the aftermarket speakers, so I thought I knew what I was getting. Well...I decided to go with these with the great sale on them right now for my 2008 Silverado and let me tell you these are some powerful speakers. As always, amazing sound quality from Polk but these ones can give you some really good thump on low end as well since they are so powerful. I wasn't expecting them to be so powerful, so very happy. Only thing is I would definitely recommend feeding a amp to these to let them reach full potential. Thank you Polk for more amazing speakers!

Pros: Amazing sound quality, very powerful, gives great low end since they are so powerful,

Cons: None

great sound

john d from port st lucie, fl on 7/31/2016

2013 Chevrolet Silverado 1500
Crutchfield Customer Review (What's this?)

Great sounding speakers. Exceeded my expectations. I would give 5 stars if they came in white.

Pros: Great sound.

Cons: Doesn't come in white.

Sounds great on my boat!

Anonymous from Gig Harbor, WA on 7/18/2016

Crutchfield Customer Review (What's this?)

Had polks as my tower speakers for 10 years, had to replace from years being in the elements.... These sound better; now hoping I get as many years as the last sets!

Pros: Great Sound!

Cons: None yet!


Mike from MN on 7/17/2016

Crutchfield Customer Review (What's this?)

Crisp, clean, & loud! Put this 6.5" pair in the roof of a side-by-side. I can hear everything no matter how I'm riding, even with the intakes Snorkeled at head level. Also makes yard chores more pleasant. Next, I'll put a couple pairs in the boat!

Pros: Clear, loud, crisp, clean, & precise loud.

Cons: Crossover needs room for install. Some applications could poise a problem.

Great mid range speakers

Ken J from Cromwell , IN on 6/22/2016

2012 Harley Davidson Ultra
Crutchfield Customer Review (What's this?)

Best sound quality speakers I've found yet.

Pros: Great speakers for their size.

Cons: rear seat pushes on the tweeters


knot sailing from st thomas, usvi on 6/21/2016

Crutchfield Customer Review (What's this?)

great sounds



Polk mm651 coaxial speakers rock!

Willy B from Manitowoc, WI on 5/29/2016

2005 Chevrolet Avalanche
Crutchfield Customer Review (What's this?)

These Polk MOMO (mm651) speakers sound incredible! Crutchfield showed that these speakers wouldn't fit in my '05 Avalanche because of the tweeter height, but I took a chance and am so glad I did! They fit perfectly, look great and sound incredibly crisp and clear. I really like the separate set of terminals which separates the tweeter from the driver/woofer and the included crossovers. So it's technically a component set and you could not use the tweeter if you wanted, and add a larger or different tweeter if that better fit your needs. I would recommend these speakers to anyone!

Pros: Swivel tweeter, separate terminal sets, crossovers, sound quality and appearance

Cons: Wiring Instructions are vague

Polk Audio MM651

Kevin from Louisiana on 5/27/2016

Crutchfield Customer Review (What's this?)


Pros: Right Product for the right job!

Cons: None.


Dave 220lx from Olive Branch, MS on 5/20/2016

Crutchfield Customer Review (What's this?)

I installed these along with a pair of MM691 and a ppi 900.4 amp in my boat. These speakers have it all. Good looks, great sound and get really loud. These are some of the best sounding marine speakers I have heard and in this price range they are the best.

Pros: Good looks Great sound Bang for the buck


2016 Harley Road Glide

Vincent from Whitehall, MI on 5/19/2016

Crutchfield Customer Review (What's this?)

Very crisp and clean sound so much better than stock

Pros: Great sound

Cons: mount base is thicker than my stock so my screws were not long enough and the screws provided were long enough just not big enough round.

Polk speakers

Michael M from Winchester, TN on 5/18/2016

2008 Ford F-150
Crutchfield Customer Review (What's this?)

Love Polk Audio products. I installed these speakers on my boat. They sound great.

Pros: Crossover included.

Cons: A little pricey but well worth the cost.

Good quality.

Spens W from Laurel, MD on 5/17/2016

2015 Chevrolet Malibu
Crutchfield Customer Review (What's this?)

For a factory upgrade these speakers are great. Easy to install but it gets a little tricky on where to mount the crossover. The quality of the highs and mids is pretty outstanding. You get great clarity at high volume level. I did wish that the bass shined through a little more especially for the price.

Pros: Great sounding highs and mids.

Cons: Need more bass.

polk mm651

js from Algonquin, IL on 5/10/2016

Crutchfield Customer Review (What's this?)

I got these for my boat because of the reviews. These things are great!

Pros: sound great, easy to install, great quality

Cons: none


Rex W. from Longview, Wa. on 4/27/2016

2007 GMC Sierra 1500 Classic
Crutchfield Customer Review (What's this?)

Easy install, great highs and mids. Needs a sub for bass.

Pros: Awesome mids and highs

Cons: None

Polk mm651 and mm691 in dodge Ram

x from Florida on 5/10/2015

These speakers sound awesome, when they work. 2 years after installing them in the stock door locations of my 2500 Dodge Ram one of the front mm691's low frequency driver just stopped working. The high frequency side is fine. The LC circuit is fine and I have never overloaded them. Also, upon removing the speaker for root cause analysis I see that the rubber surround has one small crack. In addition to this speaker having an issue, one of the rear mm651 also fried. Again the LC circuit is fine and in this case the speaker still plays, but with awful low frequency response. I spent a lot of money on these speakers and then a lot of time making them fit in the Ram. Polk brand speakers of the past were proven reliable for me, but these MM units are very disappointing.

Pros: good sound initially

Cons: Early failure. Poor durability and poor ageing. Very expensive

MM651 - 2010 FLTRX Road Glide

MattE from Rhode Island on 12/14/2012

Crutchfield Customer Review (What's this?)

Not much to say other than BUY THESE SPEAKERS. The efficiency of the drivers is outstanding, people who are not familiar with audio equipment always overlook this rating. 94dB@1Watt is extraordinary, especially when used in a motorcycle environment as in my case, they are also 3 Ohm impedance, which will draw more power from your source/amplifier (if it doesn't melt it first). The MM651 also has arguably the highest RMS/Peak power handling (when comparing realistic claims). Butyl Rubber surround, 1" tweeter and flexible installation options round out the great features of Polk's moderately priced superstar. Just do a Crutchfield comparison between the Polk MM651, the Focal K2 Power 165KRC, the JL Audio C5-650X, the Focal Performace PC 165, the Alpine SPR-60, and the Focal Integration IC 165. This comparison included speakers labelled as 6-3/4" with a (listed) price range of $199.99 all the way to $679.99. I know some people have more dollars than sense and will always buy the most expensive item available; regardless of what it is, however, I personally find it hard to stomach an extra four hundred thirty-dollars. As always Crutchfield is the go-to-source for all of the best equipment for your home and auto.

Pros: Performance > Price, 94db Sensitivity, Butyl Rubber Surround, 1" Dome Tweeter, 3-Ohm Impedance, Frequency Response, Power Handling... May I stop now?

Cons: I can only fit two on my Harley.

Polk Audio MM651

JordanZ from SLC, UT on 8/3/2012

2012 Subaru Impreza
Crutchfield Customer Review (What's this?)

These speakers do install into both the front and rear doors on a 2012 Subaru Impreza with the same caveat that Crutchfield mentions for the front doors, you have to drill new mounting screw holes. The rear doors have plenty of clearance and I just used some foam weather stripping around the speaker hole to seal up any gaps in both set of doors, it's a couple dollars at most hardware store. Other than that they couldn't sound better for being pushed with the stock receiver, can't wait till someone makes a dash mount for this car and I can throw in my receiver, amps, and subs from my old car. I know these things will sound even better with a decent amp pushing them. I grabbed these to replace the 5x7" Polk MOMO's I had in my old car that don't fit here.



Polk Audio MM651

Anonymous from jersey city, nj on 6/10/2012

2001 Hyundai Accent
Crutchfield Customer Review (What's this?)

these speakers trully deliver a punch for such small package

Pros: excellent bass


Polk Audio MM651

Rob M from Jersey Shore on 6/5/2012

2006 BMW 5 Series
Crutchfield Customer Review (What's this?)

these speakers are amazing...they sound soo good in my silverado, perfect fit. I live the external x-over..clean sound...

Pros: ez install , handle lots of power

Cons: none

Polk Audio MM651

Anonymous from Tucson AZ on 5/20/2012

2012 Jeep Wrangler Unlimited
Crutchfield Customer Review (What's this?)

These are amazing speakers. Such an improvement over the stockers. Nothing I can complain about. Crutchfield even had the lowest prices as well has having them in stock.

Pros: Ease of install Great sounding

Cons: Had to pay for them

Excellent Speakers

BrentB from Denton, TX on 5/10/2012

Crutchfield Customer Review (What's this?)

Great sound quality and build. Using them in my tower speakers on my boat.

Pros: 2 ohms, crossovers included

Cons: none

Polk Audio MM651

Anonymous from Philadelpha on 4/2/2012

2010 GMC Sierra
Crutchfield Customer Review (What's this?)

Love these speakers. I was a little worried about the crossovers that were included, but I got some connectors from Radio Shack, and it worked great. And the directions from Crutchfield were excellent!

Pros: Great sound. Easy for DIY with the directions.

Cons: None


Kelly from Texas on 3/16/2012

2007 Chevrolet Silverado 1500 Classic
Crutchfield Customer Review (What's this?)

Replaced Polk DB speakers in front door 2007 chevy pickup. Major improvement! Have the DB 4x6 plate speakers in rear. Hooked both up to 900w amp and WOW, cant believe how clear and loud. Cant lose with this speaker!


Cons: None


Mcaletzr from ochester,ny on 3/12/2012

2008 Honda Civic LX
Crutchfield Customer Review (What's this?)

I'm amazed that after ordering he mm651 Polk speakers and then receiving them, the amazement kick in when extra parts was included It made my day. Job was simple because of Crutchfield.

Pros: Parts are included

Cons: None


Chris from AZ on 3/10/2012

2006 Nissan Xterra
Crutchfield Customer Review (What's this?)

Huge improvement in sound quality over factory speakers!! I was hesitant about buying these at first because Crutchfield says they do not fit in my rear doors, but a simple template ring took care of that. No complaints at all.

Pros: Solid bass response for a 6.5in coaxial, impressive warmth.



ScottP from Moore, OK on 3/3/2012

Freakin love these speakers. I catch myself turning the radio down to find out what the unfamilar sound is, just to realize it's part of the song I'm listening to but never heard the "clarity" that you should hear. Nice base for a 6 3/4" speakers. Dropped right in on my 02 Sierra front door panels. Plan on getting some 6X9s to put under the back seat in some small enclosures... will definately go with the MM691s. In a word... Awsome.

Pros: Well made, compact magnet, Sound wicked sick Includes crossovers

Cons: NONE


anonymous from Columbia, MO on 2/8/2012

2012 Subaru Impreza
Crutchfield Customer Review (What's this?)

Using these as front speakers in an Impreza, with db651's in the rear doors. God, I wish these fit all 4 doors easily. I am using the stock head unit with no aftermarket amp or sub. These sound great. Very full sound, even at the bottom end. I listen to rock (the who, zeppelin, kyuss, local h, blue oyster cult) and these handle that type of music well. If you're into rap, get a sub. If you're cheap and still wanna rock, these are great.

Pros: full sound only need sub in very demanding applications

Cons: external crossover meant installation took 3 extra minutes of my precious time weren't free.

Polk mm651

Jaycue from Deer Park, NY. on 2/4/2012

Crutchfield Customer Review (What's this?)

These speakers sounds excellent. They put out really nice highs and midbass, the soundstage is really good. Had to modify the rear deck of my 2010 civic coupe. Sound really good at low levels.

Pros: Sound stage and quality.


Nice speakers

Tim from South WIndsor, Ct on 9/16/2011

2011 Jeep Wrangler Unlimited
Crutchfield Customer Review (What's this?)

These are great all around full range speakers. I bought these to compliment the mm components I had already installed. Crutchfield says they don't fit in a 2011 jeep wrangler but they do! In fact they fit excellent. The overall sound is good off just the deck. I have the front components amped and they sound great, so these are used to provide rear-fill. And as always, Crutchfield is superior in all ways that I have ever dealt with them. They truly are a rare company with the perfect mix of qaulity gear.



Great sound....fitment issues.

Old Subaru WRX from Earth on 6/23/2011

Cons: These speakers have a very wide basket (but are not overly deep, which is a plus). They didn't fit in the rear openings without taking an ANGLE GRINDER to my car! That said, the old WRX has terrible speaker fitment issues anyway, with any brand. Crutchfield warned me about this, but I did it anyway, so it's my fault. Also, there's a bit more work with mounting the crossovers and running dual wires, but not much. Pros: The sound. Once in, they sound amazing. Like other reviewers, there seemed to be a few-day "break-in" period with these speakers. After about a week, you can really hear all the details better, and they hit very hard for a door speaker running off a JVX XR610 (excellent, BTW) head unit. At 2.7 ohms, they will go uncomfortably loud with no distortion, and after 6 months, everything works great. Highly recommended. They sound amazing. Fitment issues were really the problem with my car and I.



Perfect complement

KENCP6 from Bakersfield, CA on 8/11/2010

Crutchfield Customer Review (What's this?)

After installing infinity reference in my rear doors and the polk mm componets in the front i quickly realized i needed an upgrade in the rear as the infinitys were not getting the job done up against the polks, "doc" at crutchfield recomended these and what a difference they are the "match" to the polk components and made all the difference, i could tell there was something missing with the infinitys but not now, putting these in the rear doors with some dynamat all around totally kicked my system up a big notch, i would recomend these to anyone looking to upgrade weather or not you have power behind it.



amazing bass

curtis from alaska on 10/28/2009

Crutchfield Customer Review (What's this?)

I have 2 sets of these in each of my vehicles. I cannot believe the amount of bass these put out. When they are broken in they sound amazing. Dont settle for a cheaper speaker , these rock!



Polk Audio MM651

gerald from titusville Fl. on 1/18/2009

I purchased 6.5's and the 6x9's to match. I replaced premium series ($500.00) 6.5's that had blown with 50 w rms and a x-over. I couldnt afford the top of the line polks, and hoped that these would tide me over till I could. AT FIRST... they sounded so horrible I couldnt believe it. I read about people saying they got better over time. They where right. After I sold the amp with built in x-over and installed diff. amp w/o x-over, I realized how much bass they really put out. The quarts couldnt compete at all as far as bass and mid bass. That extra bass pumping through them now broke them in, in a hurry. Now they sound fantastic. I wont lie and say as spacious and natural as the quarts, but the sound stage is high (right over the dash), their frequency extension is good with no harshness (the bane of Boston Pro's), and also very focused with no hole in the middle. MUCH better than I was expecting. They didnt sound good at high volume levels at first but after the break in period, now they get darn loud and sound great. The only draw back is how much my door rattles now, and the cone is kissing my factory grill making it buzz. For the price you cant beat them. Double ,triple or quadruple it and now your out of their class. Two thumbs up for me at this price.




ERNIE from NASHVILLE on 12/15/2008

Crutchfield Customer Review (What's this?)

polk mm651,installed in avalanche,all 4 doors, mounted the crossovers in the doors, mounted speakers in stock locations,trimmed the plastic round opening of the door panel so the speaker had additional clearance on excursion.use crutchfield speaker mounting rings on front doors and the polk mounting rings on the back doors,all 4 speakers are top mounted,this way you will have the clearance needed for the windows.speakers sound excellent, punchy on the lows,clear and smooth on the mids and highs.powerd by jvc headunit(20Wx4).no sub.I tryed db651s first,lack of lowend clarity.the mm651 have much better lowend.,with an over all audiophile sound,the cost differance was worth it.crutchfields service is excellant,thank you(Jordan,Jason).the next step would be to add an amplifier.



Polk Audio Rules

Richard from Elizabethtown, KY on 9/21/2008

I now have ten Polk Audio speakers crammed into the cab of a GMC cube van(used to be a moving rental van). A pair of component, two pair of eight inch subs(MM2084), and the pair of full range MM651s, all of which are driven by twenty- five hundred watts of amplifiers. I used the MM651s to "fill in a void" located in the center of the cab and BOY HOWDY did they fill it in. Now I fell like I'm "in the speaker" instead of being surrounded by them. Better yet, I can't here myself sing anymore!!!




Hands-on research

Features and Specs

Speaker Size 6 1/2
Design 2-way
Tweeter Design 1" Soft dome
Impedance (Ohms) 2.7
Tweeter Composition Silk/polymer composite
Woofer Composition Glass Fiber Composite
Woofer Surround Butyl Rubber
Parts Warranty 1 Year
Labor Warranty 1 Year
Sensitivity (1W at 1 meter) 94
Sensitivity at 2.83 volts N/A
Frequency Response 40 - 25k Hz
Minimum RMS Wattage 15
Maximum RMS Wattage 100
Peak Power Handling (Watts) 200
Top-mount Depth (Inches) 2 5/8
Bottom-mount Depth (Inches) N/A
Cutout Diameter or Length (inches) 5

Product Research


Dynamic Balance: Dynamic Balance is a proprietary Polk Audio technology using laser imaging to determine what combination of speaker materials create the least amount of resonance. Eliminating resonance in speakers results in a wide, smooth response and low distortion.

Woofer Cones: Woven glass composite cones feature tremendous stiffness-to-mass ratio. Lower mass means faster transients and finer detail.

Butyl Rubber Surrounds: For a smoother response and improved durability, the woofers use butyl rubber surrounds. The airtight rubber surrounds stand up to moisture, sunlight and extreme temperatures while allowing long excursion linear motion and years of reliable use.

Silk/Polymer Composite Swivel Tweeters: The 1" liquid-cooled, silk/polymer composite tweeters provide clear, detailed highs. The 15-degree swivel tweeter housings deliver direct, detailed imaging; instantly adjustable through the grille.

Neodymium Magnets: The speaker's neodymium magnets offer exceptional strength to performance ratio and is extremely lightweight.

Large Diameter Voice Coils: Large diameter, 30mm voice coils increase the speaker's reliability and power handling capacity.

Carbon Composite Basket: The speaker's carbon composite basket is lightweight and will not flex during music audio peaks.

Crossover: The speaker comes with two separate 2-way crossovers; one for each speaker. Each crossover's input and output wires are attached. The 38" input lead is terminated with tinned wire and the two 20" output leads (one for the woofer and one for the tweeter) are terminated with female quick-slides. The positive woofer lead has a 0.250" female quick-slide and the negative woofer lead has a 0.187" female quick-slide. The positive tweeter lead has a 0.187" female quick-slide and the negative tweeter lead has a 0.110" female quick-slide. These quick-slides connect directly to the woofer and tweeter terminals on each speaker. The 2-way crossover networks send the appropriate frequencies to each driver for cleaner sound and better imaging.

Crossover Dimensions:

  • Width: 3.5" (3.875" including wire)
  • Height: 1.02"
  • Depth: 2.645"

Mounting: The speaker itself has 4 mounting holes for a standard 6-3/4" application. The supplied mounting rings have multiple mounting holes for non-standard 6-3/4" and many 6-1/2" applications, allowing the speaker to fit more vehicles.

Grilles: Strong ABS plastic grilles are included. These computer optimized grilles feature a spoke-wheel design.

Marine Certified Woofer: Polk MM Series speakers are built to withstand exposure to moisture and UV rays, so they work well in boats and cars. They also include stainless mounting hardware for corrosion and rust resistance.

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.

Q & A

Customer Q&A

10 questions already asked

Yes as long as your amp or receiver can handle 2 separate pairs of speakers. The JL speakers are 4 ohm and the polks are basically 3 ohm. Most quality amps are 2 ohm stable and shouldn't have an issue. [ Robert  Apr 20, 2017 ]
I was going to do the same thing in conjunction with a JL audio amp and my crutchfield tech told me not to mix did ohm speakers. [ James  Apr 18, 2017 ]
Sure. You can mix and match any speakers. As long as your amp can handle the ohm load that you wire your speakers.(Parrallel or series) What you will lose, is timbre matching. In a car, I would keep the same brand and line for mids and highs. In a boat, it might not matter as much. You might not notice if you place the speakers outdoors. [ MOSES  Apr 18, 2017 ]
I have no idea about the ohms, sorry. I do think they sound real nice...... only running 40watts per channel though. [ Kevin  Feb 13, 2017 ]
For additional details on fit or installation please contact an Advisor by phone (1-800-324-9695) or online chat. They will be able to pull up your vehicle and give you the details on if this will fit and what you will need for an installation in your vehicle. [ Kenny  Feb 10, 2017 ]  Staff
Yes, they fit great, you will need 5.25x6.5 adapter rings if used on pre-14. They handle a lot of power and perform great, however, i have went through two sets of these. And I'm now running Hertz, because the tweeter posts sag and then the driver starts rubbing the post and makes the speakers pop. they don't last if you run them hard. [ Richard  Feb 03, 2017 ]
Yes in a 2014 inside the speaker pods [ Stephanie  Jan 30, 2017 ]
I put them in my 2010 Street Glide. They are not bad speakers, but at highway speeds you loose some of the volume. I ended up putting my Hog Tunes speakers back in, They are designed for bikes and sound 100% better at highway speeds. I have tried the Polk, Kenwood, Rockford Fosgate, Alpine, and I always ended up putting the Hog Tunes back in. Learned the expensive way. [ FRED D  Jan 30, 2017 ]
No, but if the hole is the correct size these speakers are pretty standard in size. I have a pair of these and do not like them at all. They do not have good midbass. I would recommend a pair of kicker marine speakers, I had way better luck with those. In addition on a motorcycle space is a concern just like it is on my boat, the crossovers on the polk speakers might be an issue and if you don't mount them may vibrate on the bike. [ GARRETT  Jan 30, 2017 ]
I do not think the crossovers are waterproof. I have them mounted in a batwing fairing on a Harley, so they stay dry. The speakers themselves have been wet many times and no problems with them so far. [ Southside  Sep 07, 2016 ]
I do not know. I was actually wondering the same myself. [ Kevin  Sep 06, 2016 ]
I wouldn't call anything "waterproof". They are marine rated so they can handle some moisture, but I wouldn't install in a known wet space or where they will get constant water contact. Outside of speaker is sealed well enough if the mounting surround is tight and flush. Crossover looks sealed, but again I wouldn't put it in a spot to get ruined. [ Mikael J.  Sep 06, 2016 ]
speaker assembly is waterproof crossover I don't think so but mine is in a console so are covered but I would hope to be water resistant since they are on a boat [ SPENCER  Sep 06, 2016 ]
The MM651 are marine certified, not waterproof. When you open the crossovers to mount them they do appear to have a significant amount of some type of coating on the circuitry to protect them, but they also have an open woofer with a stalk mounted tweeter where water can intrude. I would consider them more splash-proof or water resistant. For most situations they will be fine. The MM651UM version however has a completely sealed front and speaker mounted crossover with additional protection like you may be after. They are not available at Crutchfield however. [ Jerry  Sep 06, 2016 ]
The speaker is specified as 2.7 ohm but is 4 ohm compatible. To get the best sound you will need an amp. I am running four of these off a ppi phantom 900.4 and the sound amazing. [ William  Aug 17, 2016 ]
Sorry for fhe late response but they should do just fine on that head unit, I have them on a amp at about 75w rms and they sound nice for my particular setup [ KENNETH L  Aug 11, 2016 ]
This speaker wI'll work with any amp, aftermarket or factory receiver. Although they sound best when amplified with aproximately 100 watt per channel amplifier. [ william  Aug 10, 2016 ]
I Have 75watts going to mine and they sound great. I did read that they r designed for direct replacement oem. Always sounds better with an amp and separate sub though. To each is own. [ Jeff  Aug 09, 2016 ]
The grill is the same size as the speaker; 6 and 3/4 [ Jason  Jul 12, 2016 ]
It's been a while since I installed them but I think they are roughly 2x2x3/4". They are mounted in the middle of the included 5'-6' cables. Included are screws to mount them or you could use two faced tape. These speakers are excellent! The only weird thing is that they take a few hours of play to break in. [ James  Jul 11, 2016 ]
they are around 3" x 2" I have mine mounted on motorcycle lower a car they could mount inside door beside speakers or under dash behind radio . [ RICHARD  Jul 09, 2016 ]
As far as the dimensions go, I am guessing, but I would say 3 to 3 1/2 inches by 4 to 4 1/2 inches. There are screw holes to mount. I just used Velcro and mounted them in the kick panels. [ MOSES  Jul 09, 2016 ]
They're aproximately 3"×3"×3/4". U can mount with supplied screws or what I did was use zip ties through the slots, much easier than trying to find somewhere that your willing to put screw holes. Speakers do sound great though. [ william  Jul 08, 2016 ]
They are smaller I would say probably 2 inches by 2 inches. I put the speakers in my boat and they are amazing. Used double sided tape to mount crossovers down for a cleaner install. [ Shannon  Jul 08, 2016 ]
I can't remember exactly how large the crossovers are but they are pretty small and could fit just about any where, I had placed mine behind the door panel in a spot that would be behind a raised spot of the door panel on to the door on top of the moisture barrier so that no moisture could enter them. I also had to extend the wire for better fitment on the other set of doors. It also really depends on the vehicle and how you plan on setting up with or without an amp. If you want to set it up with a amp you could put all of the crossovers right there with the amp and let just all of the wires run to the speakers as assigned by the channels. I really hope that this was helpful in any way. [ KENNETH L  Jul 08, 2016 ]
I don't know the exact measurements, but each one is roughly 3x2, very lightweight. I have some factory tabs for the wiring loom, I simply used zip ties to hold them securely to those tabs. Hope that helps. [ Steve  Jul 08, 2016 ]
If I remember correctly they are about 1.5 x2.5. I did not mount. I left them lying on base of the enclosure. They would be mounted with a screw normally to prevent movement. One could zip tie also. [ brian  Jul 08, 2016 ]
About 3 inches by 4 inches and 2 screws mount each 1 [ Stephanie  Jul 08, 2016 ]
You can check to see if this will fit your vehicle by using our Outfit My Car tool: For additional details on fit or installation please contact an Advisor by phone (1-800-324-9695) or online chat. They will be able to pull up your vehicle and give you the details on if this will fit and what you will need for an installation in your vehicle. [ Krissy  Jun 10, 2016 ]  Staff
Thanks for your question. The SquareTrade warranty runs concurrent with the manufacturer warranty and beyond the 1 year. You can find more information on the SquareTrade link here: [ Kenny  Apr 19, 2016 ]  Staff