Polk Audio DXi521

5-1/4" 2-way car speakers

Outlet: Open Box

Item #: 107DXI521

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16 Reviews | 1 question - 2 answers


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Does it fit my car?

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Enjoy your music even more

Go ahead, circle the parking lot till your favorite song is over. Polk Audio's DXi Series speakers will make you want to hit "repeat" so you can hear it all over again. Polk uses a high-tech approach and ideal materials to give your tunes an exciting new edge.

Precision woofers showcase your music

The DXi521 speakers feature 5-1/4" polymer composite cones that are lightweight and stiff, so they can create a big sound with minimal distortion. Polk analyzes their drivers in motion to ensure that cone movement is even and precise. Polk also uses laser imaging to craft woofer cones that are perfectly balanced to resist distortion-causing resonances.

Polk Audio DXi 521

Aluminum dome tweeters broadcast detailed sound

Each 3/4" aluminum dome tweeter brings out the high-frequency highlights in your music, so you'll hear every detail of your most enthralling musical moments. From an intensely quiet acoustic pluck to the most exhilarating electric solo, it'll be a very entertaining ride.

Product Highlights:

  • 5-1/4" 2-way cars speakers (pair)
  • polymer composite woofer with butyl rubber surround
  • 3/4" aluminum dome tweeter
  • power range: 2-45 watts RMS (135 watts peak power)
  • frequency response: 60-22,000 Hz
  • sensitivity: 93 dB
  • top-mount depth: 2-5/16"
  • warranty: 1 year
  • Our 60-day money-back guarantee

Why replace your car's original speakers?

The speakers that originally came in your car were made from inexpensive materials, designed to create acceptable sound at the lowest possible cost to the manufacturer. If you love music, you deserve better. Name-brand aftermarket speakers deliver fuller, richer sound with considerably more detail and nuance, and they're capable of playing louder and cleaner than factory speakers. Connect new speakers to your factory radio and you'll get the best possible sound from your dealer-equipped system. Pair them up with a new car stereo for a level of enjoyment that can rival a high-fidelity home audio experience.

Hands-on research

What's in the box?

Download owner's manual

  • Two 2-way speakers
  • 2 Grilles
  • Eight 1" Self-tapping screws
  • Eight 3/8" Self-tapping screws
  • 8 Speed clips
  • Owner's Manual (English/ Spanish/ French/ German/ Italian/ Portuguese)
  • Online product registration information

Product Research


High Efficiency Design: The Polk Audio DXi Series speakers feature a high efficiency design; meaning better sound and more volume using less power.

Dynamic Balance Driver Technology: 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.

Klippel Optimized Components: For a driver to reproduce complex sounds accurately, the cone must move exactly the same distance and manner in both directions. The Klippel distortion analyzer, a device that uses a laser and sophisticated software to do large-scale analysis of drivers in motion, lets Polk optimize the speaker's motor structure, voice coil alignment, and suspension to yield the best possible performance.

Composite Cones: Each speaker features a Dynamic Balance, Bi-Laminate composite, polypropylene cone woofer. These composite cones feature tremendous stiffness-to mass ratio, resulting in faster transients and finer detail.

Rubber Surrounds: For a smoother response and improved durability, the speaker uses rubber surrounds.

Aluminum Dome Tweeters: Each speaker features a 3/4" aluminum dome tweeter for clear, accurate highs. Once the speakers are mounted, the tweeters can be tilted (approximately 25°) for optimum imaging.

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 open the box, verify contents, 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.

Polk Audio DXi521 Reviews

Average Customer Review:

16 reviews
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Trailblazer SS

Written By EdB., Florida Panhandle on Wednesday, October 29, 2014

Crutchfield Customer Review (What's this?)

Used these Polks to replace the rear door speakers in my Trailblazer SS. Easy to install with provided instructions, although by completely removing the speaker mounting panels underneath the door panels, you can trim the mounting much more cleanly with a sabre saw, rather than trying to break off the tabs (that interfere with installation) with pliers while still in the truck. The speakers are much less efficient than the stock factory Bose speakers, by about 30 percent, which is significant. They also have a much leaner bass and midrange response, but much cleaner highs.

Pros: Cleaner, more brilliant highs.

Cons: Much less efficient than the factory Bose speakers, less bass and midrange, so overall volume for the system is reduced.

Easy install nice sound

Written By JLmTECH, Jackson NJ on Monday, October 13, 2014

Crutchfield Customer Review (What's this?)

Good sound. Matched them with existing Polk 6x9 in the rear deck They dropped right in to the existing OEM slots. I ent with tweeter in one unit. Did not replace the OEM tweeter in the Buick 6 speaker setup. Sound great.

Pros: Great Sound, easy install

Polk Audio Speakers

Written By Jay B., Southern Maryland on Thursday, October 02, 2014

Crutchfield Customer Review (What's this?)

Love the sound. Very easy to install and fits perfectly with my motorcycle.

Pros: Did not have to splice any wires and come with a how to video if I needed it.

Cons: None.

Great Speakers

Written By Jim, New Paltz, NY on Wednesday, October 01, 2014

Crutchfield Customer Review (What's this?)

Speakers sound crisp and clear at low and high volumes

Pros: Affordable, big improvement over factory speakers, easy to install instructions

Cons: Nothing to do with the product, but be patient trying to install speakers above your head in a Jeep sound bar.

2000 Jeep Wrangler

Written By Justin, Denver, CO on Tuesday, September 16, 2014

Crutchfield Customer Review (What's this?)

Overall this speaker was an improvement to the sound quality from the factory model but at 14 years old anything would have been. After being installed for one week I would say that I'm not 100% satisfied and question my purchase. I noticed the price drop over the last 6 months with these speakers and should have taken that as a warning sign.

Pros: Improvement to the clarity. Crutchfield as always is great to work with and provides everything you need to make it work. Price

Cons: Can not use the covers it comes with. Any type of bass seems washed out and dull.

Jeep Speaker Replacements

Written By Rewards Card Reviewer, Key Largo, FL on Tuesday, September 09, 2014

Crutchfield Customer Review (What's this?)

All four 5.25"s swapped right into my 98 TJ, two dash and two soundbar. Crutchfield sent the appropriate wiring harnesses and 4x6 - 5.25" adapter for the dash; while nothing was needed for the soundbar, they sent two extra harnesses plus all hardware.

Pros: Everything needed, plus some Competitive price Marine grade

Cons: Polk grills didn't work out, but I don't like advertising anyway Top and doors are always off so I won't fully appreciate the sound

Good buy for the price

Written By gunmetalRED, Toledo, OH on Friday, July 25, 2014

Crutchfield Customer Review (What's this?)

I bought these to replace the blown front speakers in my '98 Buick Riviera and am quite happy with them. The materials and build quality felt very nice putting them in and they fit nice and flush under my factory grilles. They get nice and loud and remain clear even with my factory stereo. The bass response is OK, much better than other brands in this price range I have used, but I didn't expect them to be show-stoppers at this price. Great for highway cruising volume. I'll probably replace the rears with the matching 6"x9"s and I'm sure an aftermarket stereo would give them some nice punch. Great performance for a little money.

Pros: Price, build quality, clarity

Cons: None

Just As Bad as the DXi721

Written By CQLink, Detroit on Wednesday, July 23, 2014

Crutchfield Customer Review (What's this?)

These speakers sound muddy and dull. I installed an Alpine KTP-445U Head Unit Power Pack and it didn't help much. These are simply poor sounding speakers with virtually no bass response. Highs don't sound much better.

Pros: None.

Cons: Dull sound even with an amplifier.

Vulcan Vaquero gets an upgrade

Written By chuck, TN on Tuesday, May 20, 2014

Crutchfield Customer Review (What's this?)

These were recommended as a replacement for the factory speakers in my Kawasaki Vulcan Vaquero. The clarity has improved a lot, next will be installing an Alpine 445 amp so they can truly reach their potential. Thanks Crutchfield

Pros: Good clarity....Marine grade....awesome price

Cons: None

Polk Audio DXi521

Written By JonathaninRichmond, Richmond, Va on Sunday, April 27, 2014

Crutchfield Customer Review (What's this?)

These speakers fit my 2002 caravan great. There is a small clearance problem with the rear panel speakers which are just over the cup holders for the rear most bench. The center horn of the speaker is pressing against the plastic body panel, but we'll let time tell if that's a problem or not. The sound is great and installation was relatively simple.

Pros: Sound quality, ease of installation

Cons: Size - But that's only due to the vehicle I'm installing them on


Written By Paul, Greencastle, IN on Monday, March 10, 2014

Crutchfield Customer Review (What's this?)

Sounds great for my needs

Pros: Sounds great

Cons: Grills did not fit my soundbar on Jeep Wrangler. Had to use old ones.

Polk Audio DXi521 speakers

Written By Miike, Winston-Salem, NC on Wednesday, January 01, 2014

Crutchfield Customer Review (What's this?)

I'm very happy with the sound and ease of installation. The Crutchfield team was very helpful in my decision process.

Pros: They sound better than the old speakers.

Cons: I had to install said speakers myself, what a drag.

Good upgrade

Written By Deggy, Deforest, WI on Thursday, November 14, 2013

Crutchfield Customer Review (What's this?)

I used these in the dash of my 2005 Jeep Wrangler. I had to find a special bracket to upgrade to this size (standard is 4" or 4x6). They sound great compared to stock. It powered by a Kenwood Excelon KDC-X797 CD Receiver. The upgrade in size is much better and gives better bass and treble response.

Pros: Good value. Good sound.

Happy Customer

Written By M.E. Best, Charleston, SC on Wednesday, September 11, 2013

Crutchfield Customer Review (What's this?)

These speakers compliment the Polk DXi 651 speakers I installed earlier< I am very happy with the Polk Audio products, I am certain that they will serve me very well for years to come.

Pros: Compliments my other Polk Audio speakers with quality sound at a very competitive price.

Cons: None.

Polk Audio DXi521

Written By TimH, Ketchum, ID on Friday, August 02, 2013

Crutchfield Customer Review (What's this?)

Nice little set of speakers. Well built with solid grills. I installed them in my boat with the Kenwood KMR-355U receiver unit, and am enjoying the upgrade.

Nice Sound, worth the upgrade

Written By Mack, Harrisonburg,Va on Saturday, July 27, 2013

Just purchased a 2012 Jeep Wrangler without the upgraded sound system. The stock speakers were lousy. I upgraded the speakers in the sound bar first. A week later I had to upgrade the speakers in the dash. I left the stock head unit. I put the Polk's in the front panels. Speakers sound great. No more muddy bass. The install took awhile, but that is because it is a Jeep. Sounds good with the stock head unit. Big, big difference.

Pros: Sound great. Good overall sound.

Cons: Difficult install in a 2012 Jeep Wrangler. Not the speakers fault. -- Jeeps fault.

Get everything you’ll need to enjoy your new Polk Audio DXi521

Reduce ambient road noise and your vehicle's "rattles," for better sound inside your car.
You may need speaker wire to connect your speakers to your amp or receiver.
Keep your speakers clean and dry. They compress to fit behind your speakers.
These speaker connectors are handy if you're running new speaker wire or if your speakers have oversized terminals.
The right tools will help keep your installation simple and clean.
If your stereo doesn't cut the deep bass from your full-range speakers, a set of bass blockers can help prevent distortion and give you cleaner bass too.
Dynamat 10415 Xtreme Speaker Kit

Dynamat 10415 Xtreme Speaker Kit

Two 10-in. x 10-in. Sheets

Item #: 15410415


Add to Cart
Dynamat 10435 Xtreme Door Kit

Dynamat 10435 Xtreme Door Kit

With four 12" x 36" sheets — covers two doors

Item #: 15410435


Add to Cart
Dynamat SuperLite Tri-Pak

Dynamat SuperLite Tri-Pak

Triple package — 3 sheets, 12 square feet (Model #10612)

Item #: 15410612


Add to Cart
T-Spec 16-gauge Speaker Wire

T-Spec 16-gauge Speaker Wire

Black/white jacket — priced per foot

Item #: 120SW16WB1


Stinger PRO Series Speaker Wire

Stinger PRO Series Speaker Wire

Priced per foot (16 Gauge)

Item #: 541SPW516B


T-Spec 12-gauge Speaker Wire

T-Spec 12-gauge Speaker Wire

Black/white jacket — priced per foot

Item #: 120SW12WB1


XTC 5-1/4

XTC 5-1/4" Speaker Baffles

Protect your speakers (3-3/4" depth)

Item #: 237XT55


Add to Cart
Boom Mat 5-1/4-inch Speaker Baffles

Boom Mat 5-1/4-inch Speaker Baffles

Protect your speakers
Regular and slim-line sizes (Regular: 4" depth)

Item #: 696B050320


Add to Cart
Metra Female Quick Slides

Metra Female Quick Slides

An assortment of female quick slide connectors for connecting to speaker terminals

Item #: 120FQS10PK


Metra Crimp Tool and Connectors

Metra Crimp Tool and Connectors

Package contains crimp tool and over 150 pieces

Item #: 120CRIMPKT


Add to Cart
S&G Wire Cutter/Stripper Tool

S&G Wire Cutter/Stripper Tool

Cuts and strips 12- to 22-gauge wire

Item #: 18119100


Add to Cart
Bojo Trim Panel Tools

Bojo Trim Panel Tools

Set of 6 pry tools — helps remove interior and exterior trim and door panels

Item #: 126CR6NGL


Add to Cart
Pro.Fit Wire Worm

Pro.Fit Wire Worm

Installation tool helps route wiring through tight spaces

Item #: 042DM4533


Add to Cart
S&G Tool Aid 87615

S&G Tool Aid 87615

Window and Door Clip Removal Tool

Item #: 18187615


S&G Tool Aid 87650

S&G Tool Aid 87650

Door Trim and Panel Removal Tool

Item #: 18187650


Skewdriver Pro SPK4042

Skewdriver Pro SPK4042

Ratcheting straight and offset screwdriver set with 40 bits (Skewdriver Pro with ratchet handle, pictured)

Item #: 180SPK4042


Add to Cart
Spec Tools SQR-200a Squeeze Wrench

Spec Tools SQR-200a Squeeze Wrench

Narrow space ratchet kit with 18 sockets

Item #: 180SQR200A


Add to Cart
Bojo Trim Panel Tools

Bojo Trim Panel Tools

Set of 6 pry tools — helps remove interior and exterior trim and door panels

Item #: 126CR6LNGL


Add to Cart
Posi-Products™ Car Speaker Connectors

Posi-Products™ Car Speaker Connectors

8 connectors for installing car speakers

Item #: 669PP502


Add to Cart
DEI Heat Shrink Tubing

DEI Heat Shrink Tubing

Black 4-foot length (Assortment)

Item #: 696010839


Add to Cart
Bass Blockers

Bass Blockers

Pairs (300 Hz cut-off)

Item #: 127BB300A2


Questions & Answers Ask the community. Share your knowledge.

1 question already asked

I'm sure they could be modded to be biampable, but out of the box, no. [ TOM  May 28, 2014 ]
They only have one positive and negative connection on the back for the whole speaker... There isn't a separate connection for the tweeter. Not sure if that helps or not. [ Brian  May 28, 2014 ]