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Polk Audio db840

180W 8" db Series Single 4 ohm Marine Certified Subwoofer

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List price $99.99

$54.95

with warranty

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Product Features

  • 8" Single 4 Ohm Marine Certified Subwoofer
  • Power Handling:
    • Peak: 360 watts
    • RMS: 180 watts
  • Impedance: Single 4 ohm
  • Polypropylene cone woofer
  • Santoprene rubber surround
  • Marine certified: capable of withstanding harsh marine environment
  • Vented coil coupler
  • Fire-retardant NOMEX spider with linear motion
  • Designed and aligned with Klippel laser analyzer
  • Triple vented 4-layer Kapton single 4 ohms voice coil
  • Frequency response: 30-200 Hz
  • Sensitivity: 85 dB
  • db Series Subwoofer Grill Available
  • 1-year SonicElectronix.com warranty

Product History:

Polk Audio db840 thumbnail
(newest, current model)
Polk Audio db804 thumbnail
(previous model, replaced by Polk Audio db840)

Subwoofer Specifications

Subwoofer Series
Each subwoofer manufactured is part of a series. This is the name of the subwoofer's series.
db (Polk)
Subwoofer Size
Refers to the diameter of the subwoofer, measured in inches.
8"
Peak Power Handling
Peak power handling refers to the amount of power a speaker can handle during a brief musical burst. The RMS power range figure is a much more reliable rating for determining the speaker's power requirements. The Peak power handling specification is typically rated per speaker unless otherwise noted.
360 watts
RMS Power Handling
The RMS power is the amount of power the speaker requires to operate safely and properly. RMS Power Handling refers to the amount of power a speaker can handle on a continuous basis. We recommend powering your speakers or subwoofer with 80%-120% of its recommended RMS rating. The RMS power handling specification is typically rated per speaker unless otherwise noted.
180 watts
Voice Coil(s)
Dual voice coil subs have more wiring flexibility than single voice coils subs; however, single voice coil subwoofers provide easier hookup options for wiring multiple subwoofers in parallel or series. You may also run a dual voice coil (DVC) sub in parallel, series, or combination. A quad voice coil has four voice coils and is equal to two dual voice coil subwoofers as far as wiring goes.
Single
Impedance (Per Voice Coil)
The load value (in ohms) that the speakers present to the amplifier per voice coil - the amount of resistance to the current flow. This is a key specification as subs wired in parallel or low impedances can create problems with your amplifier and potentially void all warranties. We encourage you to ask our support department prior to purchase if you do not understand which impedance level will suit your application best.
4 ohms
Frequency Response
The range of frequencies the speaker will reproduce (lowest frequency to the highest). Bigger is better, meaning the wider the range, the better. The optimal range is 20 - 20,000 Hz (which is the range of human hearing).
30 - 200 Hz
Sensitivity
An efficiency or sensitivity rating tells you how effectively a speaker converts power into sound. The higher the number, the more efficient the speaker and the louder it will play with the same input power. An efficient speaker helps you maximize your available power. Most sensitivity ratings measure the speaker's output with 1 watt of input, 1 meter from the speaker. Some speakers' sensitivity is measured with 2.83 volts of input, instead of 1 watt.
 
Efficiency (1w/1m) is not an accurate indicator of a subwoofer's output capability and should not be used as a comparison to other speakers or subwoofers to determine which one is "louder".
85 dB
Xmax (millimeters)
Typically measured in millimeters, the Xmax value is the measure of a speaker cone's maximum excursion in one direction while maintaining a linear behavior.
6.1 mm
Subwoofer Design
This is the design of the subwoofer or the opening of the subwoofer enclosure. Each design has it's own benefits, whether it is a square, circle, or oval.

Round/Circle: This is the typical and common subwoofer design. They have a round cone and are a circle in design.

Square: These woofers are able to achieve a greater cone area in a smaller space. Because of the greater surface area, some square subwoofers will be louder than a round subwoofer of the same size.

Round / Circle
Main Cone Color
This is the color of the speaker's or subwoofer's cone.
Black
Woofer Composition
Lightweight woofer cone materials are essential for efficient operation. Poly cones produce exceptional sound and are sturdy against various changes in temperature. Paper cones are very efficient, and when treated for moisture resistance, will perform at a high level. Poly refers to polypropylene, which is thermoplastic or fibers that are polymers of propylene. IMPP refers to injection molded polypropylene, a commonly used process and material in speakers.
Polypropylene
Woofer Surround
A speakers surround is part of the suspension system. The surround protects the cone and prevents it from being displaced as it flexes out from the basket. It is usually made of a durable material like treated foam or rubber in order to withstand the strenuous job of producing bass frequencies.
Santoprene Rubber
Subwoofer Grille
Most subwoofers are able to accommodate a universal grille; however, some subs include a grille and others have a specific, optional grille available for purchase separately. If "yes", then the subwoofer includes a grille. If "optional (sold separately)" the matching grille will need to be purchased in addition to the sub.
No
Re-Cone Kit Available
Some higher end subwoofers have replaceable cone assemblies. In case of a blown woofer, a recone kit allows for a simple replacement, as opposed to purchasing an entire new subwoofer.
No

Recommended Enclosure Specifications

Recommended Enclosure Type
This is the recommended type of enclosure that the subwoofer should be installed into. Some subwoofers are specially designed for particular enclosures.

Sealed: These enclosures completely enclose the air inside the box. These boxes produce a tight bass.

Ported/Vented: These enclosures have a slot of air to escape from the box. The result is a sound that has more "boom".

Bandpass: These are a combination of both sealed and ported enclosures. They can be very efficient, but require tuning for the best response.

Ported / Vented
Sealed
Top-Mount Depth
The depth when installed on top of the mounting surface. Measured from the bottom of the speaker's magnet to the bottom of the mounting holes on the rim of the speaker.
4"
Cutout Diameter
The actual diameter of the hole you will need to cut out if you are creating a new mounting location for this speaker, or if you are mounting a subwoofer in a box.
7-1/16"
Shallow Mount Installation
This means that the subwoofer/speaker is designed to be installed in areas that do not have a lot of space. Shallow mount subwoofers are typically found under a seat or behind the seat in some trucks.

Shallow mount speakers will typically have a mounting depth of 2" or less, while shallow mount subwoofers will typically have a mounting depth of 3" or less.

No

Warranty and Return Policy

Parts Warranty Duration
1 year
Labor Warranty Duration
1 year
Warranty Provider
Sonic Electronix

Summary of Customer Ratings & Reviews

Rating Distribution

5 Star
75%
4 Star
25%
3 Star
0%
2 Star
0%
1 Star
0%

Average Attribution Rating

Durability
4.8
Value
4.8
Features
4.7
Design
4.5
Usability
4.9
usmc

redding, ca.

Overall
Durability
Value
Features
Design
Usability
Polk DB 804

July 24, 2014

I purchased these for some DJ speakers for the mid bass. These sound great and heave very clear sound. I have then wire in series for a 8 ohm load and am pushing 350 watts RMS and these handle it like a champ. The studio amps I am using have a cut off of 100 hz on BI-Amp mode which helps these handle more power than the rating. These are a great deal for the money and do everything I expect of them. I would definitely recommend these If you want quality sound and know what you are doing.

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Jon

Fayetteville, NC

Overall
Durability
Value
Features
Design
Usability
Great Value!

June 2, 2012

Added to stock system to extend bass response. Put in a sealed .274 cf stuffed box powered by KAC 1502. Tight, efficient bass!

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Selders

Kansas City, MO

Overall
Durability
Value
Features
Design
Usability
Outstanding performance

May 2, 2012

Product was far better than the original stock woofer that it replaced, and has been solid as a rock since I installed it. Sounds great!

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Cope

Atlanta, Ga

Overall
Durability
Value
Features
Design
Usability
Good Buy!

May 1, 2012

6 months and counting. I love the fact that my db840's are marine certified because I have them in my Goldwing motorcycle and they have performed flawlessly. Can't wait to push these babies with the marine amp that I purchase.d from Sonic. The clear vocals and crisp sounds from these speakers should fair well with the 9 in sub that I also purchased from Sonics.

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Tyler

Iron Station, NC

Overall
Durability
Value
Features
Design
Usability
Great 8

October 31, 2011

This sub is perfect for anyone wantin some added bass, its got a low price point and its reasonably shallow so it wont take up too much room. Polk is a reliable brand in my opinion also.

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Rusty

Mandeville, La

Overall
Durability
Value
Features
Design
Usability
Excellent value, quality and sound

August 20, 2011

Added the Polk db840 to my golf cart sound system in conjunction with a pair of the Polk db651s. Sound from the db840 is awesome. Nice clean lows.

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Marco

PEORIA, AZ

Overall
Durability
Value
Features
Design
Usability
Polk audio

August 12, 2011

The Polk Audio works great like it a lot. Sounds great in my truck.

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Rick

Ocoee, FL

Overall
Durability
Value
Features
Design
Usability
good deal

July 10, 2011

sound and look good

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Gil

Orange, Texas

Overall
Durability
Value
Features
Design
Usability
Awesome Polk Speakers

February 8, 2011

These are great sounding speakers and they can really handle the power and still sound great. I installed these on my Polaris RZR 4 and I really do like these speakers.

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lance

wildomar CA

Overall
Durability
Value
Features
Design
Usability
love polk

November 9, 2010

good subs great value have never heard 4 8s sound like this before

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jackbequick

Texas

Overall
Durability
Value
Features
Design
Usability
Nice little sub

June 25, 2010

I built a custom box for this sub under the floor in my hatch by the spare tire - pretty much .35 cu ft. I went with this woofer due to my positive experience with polk component speakers and it's super shallow mounting depth. It seemed to lack low lows until broken in but now I just can't say how impressed I am with an 8" woof. I have my amp bridged at 300 watt rms and the woof seems to do fine even though it is rated at 180 watts. For reference, I've got an equalizer built in to my head unit and a 40 Hz bass boost on my amp that might really be helping me dial in the sound. The lows go low enough and the high/mid bass is more pronounced. It is a quality sound not a boomy sound. That said, if you are looking to wake the neighbors from 2 blocks away, get a couple of 10's or 12's.

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jesse

tyler tx

Overall
Durability
Value
Features
Design
Usability
great value

February 11, 2010

great speaker for the price. hard to find a direct replacement for a Yukon sub. fit great

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Accessory Tools and Products

Accessories added

25 ft. of Streetwires 12 Gauge Speaker Cable

You'll need speaker wire to hook up that new subwoofer!

Your Price $44.95

20 Square Feet of Sound Dampening Material

NVX Sound dampening is thicker than competitors, eliminates rattles and gives you bigger bass!

Your Price $59.99

Dynamat Sound Dampening Trunk Kit

Did you know sound dampening will reduce those annoying rattles and even increase your SPL?

Your Price $109.95

Stinger Sound Dampening Trunk Kit

Stinger's Roadkill sound dampening series is sure to kill unwanted road noise and rattles! Enough sound dampening for your whole trunk!

Your Price $69.99

12 oz. Can of Adhesive Spray

Spray adhesive used for adhering carpet to subwoofer boxes without bubbles.

Your Price $6.99

Spring Post Terminal Cup

Makes adding a spring post terminal to an enclosure simple! Banana clip ready!

Your Price $3.99

Gold Plated Dual Terminal Banana Plug Connector

Enables an expandable, secure connection accepting up to 8 gauge wire.

Your Price $1.99

Car Stereo and Speaker Installation Tool Kit

Includes Test Light, Crimp/Splice Tool, Multi-bit Screwdriver and more.

Your Price $14.99

Xscorpion 9-Piece Nylon Plastic Pry and Chisel Tool Set

Easily removes dash/trims, door clips, panels and pins, rubber grommets and vehicle emblems.

Your Price $14.99

Cordless Multi-Functional Heat Tool Soldering Iron Kit

Continuous working lock allows you to work without holding down trigger.

Your Price $79.99

4 Ft of 1/4" Thick Black Heat Shrink Tubing

Provides abrasion resistance and added protection for your cables.

Your Price $3.99

2" Universal, Professional Heavy Duty Roller for Sound Damping/Dampening

Universal rubber roller to make it easy to install sound dampening.

Your Price $7.99

1mm All Purpose Solder

Solder is all purpose for use on most projects where solder is needed.

Your Price $8.99

Polk Audio DB8G

8" db Series Subwoofer Grille

Your Price $20.99

Scosche SPL Meter

Monitor the noise level of your new car audio system with this SPL meter measuring from 60-135 dB.

Your Price $21.99

Impedance Meter / Signal Generator

Easy to locate tuning frequencies of passive radiators and ported enclosures

Your Price $299.99

1 Polk Audio db840 Subwoofer

Mono Amp

2 Channel Amp - Bridged

2 Polk Audio db840 Subwoofers

Mono Amp

2 Channel Amp

4 Channel Amp - Bridged

3 Polk Audio db840 Subwoofers

4 Channel Amp

4 Polk Audio db840 Subwoofers

Mono Amp

Mono Amp - Option 1

2 Channel Amp

2 Channel Amp - Bridged

4 Channel Amp

Browse 1 question and 1 answer
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Why did you choose this?
Sonic Electronix Store
Recommended by sonic customer service
david j on Aug 27, 2014

Product Summary

Manufacturer

Model Number

db840

UPC

747192113766

Weight

7.00lbs

Internal SKU

db840

Internal Product ID

12333

Sonic Electronix Wiring Guide

Wiring Diagram Legend

Warning: The image depicted shows the resistance change when wiring multiple subwoofer terminals. Please refer to your subwoofer's owner's manual for the proper wiring of its terminals. Sonic Electronix, Inc. is not responsible for damage caused to your audio system or vehicle due to improper installation. Please call tech support at 1-877-289-7664 if you require additional assistance.

Product Name: Polk Audio db840