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Polk Audio db5251

5-1/4" component speaker system

Item # 107DB5251

Good music becomes great when you hear it through Polk's db Series car speakers.

Find what Fits your car

Good music becomes great when you hear it through Polk's db Series car speakers.

Discontinued item
8 questions - 18 answers

Item # 107DB5251

About the Polk Audio db5251

Polk precision

Good music becomes great when you hear it through Polk's db Series car speakers. Polk engineers use laser imaging to determine the ideal combination of speaker materials and design to eliminate distortion. The resulting technology produces speakers with smooth frequency response, sharp detail, and the ability to play music at high volumes without strain.
Polk Audio db5251

Polk precision

Good music becomes great when you hear it through Polk's db Series car speakers. Polk engineers use laser imaging to determine the ideal combination of speaker materials and design to eliminate distortion. The resulting technology produces speakers with smooth frequency response, sharp detail, and the ability to play music at high volumes without strain.

Polk's versatile db5251 component speaker system features 5-1/4" woofers made from a polymer/mica composite and durable rubber surrounds that won't fall apart under stress from heat, moisture, or time. Liquid-cooled 1" silk/polymer dome tweeters use powerful Neodymium magnets to deliver precise high-frequency reproduction, enveloping you in bright musical detail. You can surface- or flush-mount the tweeters with the included swivel-mount cups. Just aim the tweeters so they broadcast toward your ears, creating a powerful stereo image.

External crossovers direct the right frequencies to the tweeters and woofers to maximize their performance, and their housings let you hide all wiring for a clean, professional look. These speakers feature stainless steel mounting hardware, plus muscular ABS grilles that will add a stylish touch to your car's interior. And Polk certifies their db Series speakers for marine applications, so they're a great choice for your boat, motorcycle, or ATV.

Installation note: You'll need a pair of our universal backstraps to install the tweeters in the factory locations.

Priced per system


Product highlights:

  • component speaker system includes two 5-1/4" woofers, 2 tweeters, and 2 crossovers
  • Dynamic Balance polymer/mica composite woofers with butyl rubber surrounds
  • Kapton voice coils
  • 1" liquid-cooled silk/polymer composite dome tweeters
  • flush- and surface-mount swivel cups
  • Neodymium tweeter magnets
  • electronic tweeter protection circuits
  • 2-way external crossover network (12 dB/octave, 4,000 Hz high- and low-pass)
  • marine-certified for use in boats, convertibles, motorcycles, and ATVs
  • ABS wheel-design grilles
  • stainless steel mounting hardware
  • power range: 10-100 watts RMS (250 watts peak power)
  • frequency response: 53-23,000 Hz
  • sensitivity: 93 dB
  • top-mount depth: 2-5/16"
  • warranty: 1 year
  • Our 60-day money-back guarantee
  • MFR # AA5251-A

What's in the box:

  • 2 Woofers
  • 2 Grilles
  • 2 Tweeters (each tweeter has attached 38" speaker leads)
  • 2 Flush-mount cups
  • 2 Metal flush-mount clamps
  • 2 Surface-mount cups
  • 2 Crossovers
  • Four 39" lengths of speaker wire (each length of wire has female quick-slides on one end and tinned wire on the other end)
  • 16 Self-tapping screws
  • 10 Speed clips
  • Owner's Manual (Eng/Span/Fren/Ger/Ita/Port)
  • Online registration sheet

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Polk Audio db5251 reviews

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Crutchfield response

<< >>

More details on the Polk Audio db5251

Pat M.

Features & specs

Speaker Size
Design 2-way
Tweeter Design 1" Dome
Impedance (Ohms) 4
Tweeter Composition Silk polymer composite
Woofer Composition Polymer mica composite
Woofer Surround Butyl rubber
Parts Warranty 1 Year
Labor Warranty 1 Year
Sensitivity (1W at 1 meter) 93
Sensitivity at 2.83 volts N/A
Frequency Response 53 - 23k Hz
Minimum RMS Wattage 10
Maximum RMS Wattage 100
Peak Power Handling (Watts) 250
Top-mount Depth (Inches) 2 5/16
Bottom-mount Depth (Inches) N/A
Cutout Diameter or Length (inches) 4 3/4
Mounting Height (Inches) 0.161
The Polk Audio db5251 replaces these items:

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: Each speaker features a Dynamic Balance polymer/mica composite mineral-filled cone. The cones are stiff and lightweight for big sound and low distortion.

Butyl Rubber Surrounds: For a smoother response and improved durability, the woofers use butyl rubber surrounds.

Kapton Voice Coil Formers: The low-mass 2-Layer 1" Kapton Voice Coil formers are lightweight for high sound output. Kapton's high melting temperature ensures high power handling and excellent reliability.

Pole Plate Heat Sinks: The pole plate heat sinks promote better heat dissipation for superior power handling and reliability.


Silk/Polymer Composite Tweeters: The 1" liquid-cooled, silk/polymer composite tweeters provide clear, detailed highs.

Mounting: The supplied mounting cups allow you to surface- or flush-mount the tweeters. The tweeters swivel in the flush-mount housings, allowing you to adjust them for optimum imaging.

Tweeter Mounting Dimensions:

  Surface Mount Flush Mount
Mounting Height 1.046" 0.364"
Depth 0.825" (screw depth) 0.938"
Frame Diameter 2.002" 2.297"
Cutout Diameter   N/A 1.951"


2-Way Crossovers: Each Butterworth outboard crossover features a 12dB/octave, 4000Hz high-pass network for the tweeter and a 12dB/octave, 4000Hz low-pass network for the woofer.

Tweeter Attenuation Switch: You can adjust the output of the tweeter to match a level appropriate to your vehicle or your system. On the end of crossover (opposite the terminals), the tweeter attenuation switch can be set to 0dB, -3dB, or +3dB.

Electronic Tweeter Protection Circuits: Each crossover has a built-in protection circuit that guards the tweeter against accidental damage from high power.

Crossover Connections: The crossover inputs and outputs are screw terminals. The crossover housing is vented, giving you a choice of hidden wire channels for easier, more professional-looking installs.

Mounting: There are two mounting holes in the base of each crossover.

Crossover Dimensions: L=5.029", W=3.072", H=1.075"

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Customer Q&A

Crutchfield asked: Why did you buy this?
I LOVE these speakers in my previous vehicle. Buying them again!! [ Cliff  Aug 29, 2016 ]
I am not a fanboy of any particular brand. I have used Polk before, and I am budget minded. I needed to replace the crumby speakers on my pontoon, and these fit the bill. The RMS was what I wanted, and it is marine rated. Eventually I will add a mono block with a sub, and a 4 channel amp to power these speakers. Until then, these should do the trick. Thank you, Crutchfield for making things a breeze! Tim in customer service was helpful, keep up the good work, man! Tim's Bio: [ Shane  Jul 05, 2016 ]
Best choice for the money. [ D  Jun 25, 2016 ]
Cause these speakers rock :) [ Doug  Jun 11, 2016 ]
I have Polk in all my other cars their awesome Just buy them you're going to love them once you're in your car [ johnathan  May 29, 2016 ]
Awesome sound, components, etc. [ SCOTT  Apr 03, 2016 ]
Great price. I'm a fan of Polk home audio and their car audio blew me away. This is a great component system at a very fair price. If you get these get a sub. They don't truly shine until they shed off a the little low end onto a sub. Highly recommended. [ Messman Motorcy  Mar 12, 2016 ]
Good Reviews, recommended by Conrad from Crutchfield. This is known as best budget component system. [ Dan  Feb 29, 2016 ]
Good RMS [ R.TERESKO  Feb 22, 2016 ]
Brand, and Price [ G E  Feb 18, 2016 ]
These speakers are marine grade and will be going into a Jeep. Plus I wanted a component speaker. [ Ed  Feb 07, 2016 ]
Our family likes polk car speakers. [ Kelly  Feb 07, 2016 ]
I used polk speakers before, sale price and product features attracted me. [ Quamrul  Jan 29, 2016 ]
good reviews, know brand. [ Sherri  Jan 19, 2016 ]
On sale , great frequentcy response!!! [ Donald  Jan 15, 2016 ]
Outstanding experience with Polk Audio speakers! [ ERIC  Dec 21, 2015 ]
Expected Polk quality sound and construction [ James  Dec 15, 2015 ]
Recommended fit to my vehicle and the reviews were great. I had Polk 6x9's in the past and they were superb so I think these should be even better. [ G  Dec 07, 2015 ]

8 questions already asked

How do these sound with 45 watts RMS power? I am looking into getting the Alpine Power Pack KTP-445U Amplifier to use with these speakers.
[ joshk8819  Jul 06, 2016 ]
2 answers
Hey Josh, I'm sorry to say I never bought an Alpine KTP-445U power pack. But, on the other hand db5251 sound great no matter what your using. I've used Rockford Fosgate and worked great. Never had a problem. Good Luck, Eric S.
[ Eric  Jul 06, 2016 ]
I would get a amp with the same RMS so it's really clear at high volume.
[ KERTTON  Jul 06, 2016 ]
What ohm are the voice coil on these speakers?
[ Zach  Jul 01, 2016 ]
4 answers
I don't know off hand, but you should find it under product specifications
[ Roy  Jul 02, 2016 ]
4 ohm, they are very good
[ JAVIER  Jul 01, 2016 ]
4 ohm
[ Daniel  Jul 01, 2016 ]
Per the online manual, the nominal impedance is 4 ohms
[ Eric  Jul 01, 2016 ]
What 4 channel amp can I use with these or what should I look for?
[ Cochiloco  May 26, 2016 ]
3 answers
Im currently using the Sound Ordinance M-4050, I works well but I didn't expect it to be so big! I should've spent the $50 extra to get the kenwood or maybe an alpine. Usually any big brand with 50 watts RMS and up for each channel should be good. Check your impedance values and make sure that they match up or else you could fry and amp. I think most should be matched already.
[ David  May 26, 2016 ]
Any 4 channel amp should be fine. I used a low power 4 channel, 2 channels bridged for my bazooka bass tube in the trunk (i had no where else to put it). I had a very small Z3 so much power was not necessary. Speakers sounded fine with only the head unit power also
[ MIKE R  May 26, 2016 ]
The power of a system is measured in watts for both amplifier output and speaker power handling. Keeping a good balance between these numbers will give you the best results. I recommend having your speaker's power handling equal to, or slightly over, the RMS/continuous power output of your amplifier. I honestly didn't power them with an amp. They sound really good when properly tuned on a decent head unit.
[ John  May 26, 2016 ]
How do the tweeters mount, surface or flush,if flush what size to opening is needed?
[ Nuna  Jan 06, 2016 ]
1 answer
The speakers come packaged with both surface & flush mount bracket options for the tweeters. You will find this information (as well as the mounting dimensions for each) by clicking the "Details" tab on the speaker's main webpage and scrolling down below the "Features & Specs" table. I hope that helps! My Bio:
[ Ryan  Jan 08, 2016 ]  Staff
Do these fit a Toyota Tacoma Double Cab truck (non JBL) both front and rear doors?
[ Kevin  Jan 06, 2016 ]
1 answer
For 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  Jan 06, 2016 ]  Staff
How many speakers come with this exactly?
[ gage_aiden15  Dec 21, 2015 ]
5 answers
4 speakers total
[ FRANKLIN E  Dec 25, 2015 ]
Four; two low/mid range speakers and two tweeters/high range speakers, one each for left and right, with a crossover for each pair
[ Robert  Dec 23, 2015 ]
2 tweeters and 2 speakers
[ BANCROFT  Dec 22, 2015 ]
You will receive a total of (4) speakers, (2) tweeters and (2) 6 1/2 or 6 3/4) including the two component devices to drive both the front left, and front right or depending on where you install your speakers. I bought two sets of these for the front and rear of the vehicle. I also recommend installing a good Amp to allow for optimal sound, These speakers are designed for power.
[ SCOTT  Dec 22, 2015 ]
This component speaker system includes two 5-1/4" woofers, 2 tweeters, and 2 crossovers. So there would be 4 speakers total, 2 woofers, 2 tweeters. The two external crossovers direct the right frequencies to the tweeters and woofers to maximize their performance.
[ Kenny  Dec 22, 2015 ]  Staff
Has anyone installed these speakers in a BMW Z3? And if so, did you use the stock grills? And they sound as good or better then the stock? I am also using a stock Blaupunkt head unit
[ JC  Jun 17, 2014 ]
1 answer
I had these speakers installed in my '03 mitsubishi lancer & they are way better then stock speakers in my opinion. A must buy in my book.
[ Jackson  Jun 17, 2014 ]

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