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Kicker 40CSS684

6"x8" component speaker system

66 Reviews | 5 questions - 13 answers

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Our take on the Kicker 40CSS684

Upgrading the old factory speakers in your car will give you a huge bump in sound quality, and Kicker designed CS Series speakers to get your sound system rockin' without breaking the bank. You'll enjoy your music even more when you hear all the details that your muddy-sounding factory speakers couldn't begin to reproduce.  

Kicker 40CSS684

It's time for an upgrade

Upgrading the old factory speakers in your car will give you a huge bump in sound quality, and Kicker designed CS Series speakers to get your sound system rockin' without breaking the bank. You'll enjoy your music even more when you hear all the details that your muddy-sounding factory speakers couldn't begin to reproduce.  

Bring on the treble and the bass

Kicker's 40CSS684 component speaker set provides low-end from a tough 6"x8" polypropylene woofer, with a polyester foam surround that will stay strong for years to come. The separate 3/4" titanium dome tweeter takes care of the vocal and instrumental details that'll really bring your music to life. The outboard crossover network allows you to pick from three different tweeter level settings so you'll get balanced sound wherever you're sitting.

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

Great sound, I'm replaced my stock speakers. I upgraded to these kickers in the front with a tweeter and the sound is just awesome. I also put the speakers baffles in and that was the ticket. I can't wait to upgrade the deck unit with these speakers

Tim, Lovelock, NV

Featured Video:

What's in the Box:

  • Two woofers
  • Two tweeters (each with 35" Wire attached)
  • 2 Crossovers (each with 35" Input wire/ 35" Tweeter output wire/ 35" Woofer output wire attached)
  • 2 Flush mount tweeter rings
  • 2 Short tweeter mounting nuts
  • 2 Long tweeter mounting nuts
  • 2 Back angled tweeter rings
  • 2 Front angled tweeter rings
  • 2 Angled surface mount tweeter housings
  • Twelve 1" Self-tapping screws
  • Two 5/8" Self-tapping screws
  • 8 Speed clips
  • Four 7" Zip-ties
  • 4 Red plastic butt connectors
  • Owner's manual (English/ Spanish/ German/ French)

Product Highlights:

  • component speaker system includes 2 woofers, 2 tweeters, and 2 crossovers
  • 6"x8" polypropylene woofers with polyester foam surrounds
  • 3/4" titanium dome tweeters
  • external crossover network with 3 tweeter levels (0, +3, +6 dB)
  • power range: 2-75 watts RMS (225 watts peak power)
  • frequency response: 40-21,000 Hz
  • sensitivity: 90 dB
  • top-mount depth: 2-5/16"
  • warranty: 1 year
  • Our 60-day money-back guarantee

Kicker 40CSS684 Reviews

Average Customer Review(s):

(66 Reviews)
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Hands-on research

Features and Specs

Speaker Size 6X8
Design 2-way
Tweeter Design 3/4" Dome
Tweeter Composition Titanium
Woofer Composition Polypropylene
Woofer Surround Polyester Foam
Parts Warranty 1 Year
Labor Warranty 1 Year
Sensitivity (1W at 1 meter) 90
Sensitivity at 2.83 volts N/A
Frequency Response 40 - 21k Hz
Minimum RMS Wattage 2
Maximum RMS Wattage 75
Peak Power Handling (Watts) 225
Impedance (Ohms) 4
Top-mount Depth (Inches) 2 5/16
Bottom-mount Depth (Inches) 2 11/16
Cutout Diameter or Length (inches) 0

Product Research


Polypropylene Woofer Cones: The Kicker CS-series speakers feature durable polypropylene woofer cones, resistant to the moisture and temperature extremes found in automotive applications.

Woofer Mounting Applications: While Kicker describes this speaker as a 6x8, it also fits many 5x7 applications. Please check the Crutchfield Vehicle Selector to confirm fit.

Ribbed Polyester Foam Surrounds: The ribbed polyester foam surrounds allow extended cone excursion for additional bass output and higher SPL.

Tweeter Mounting Options: The tweeters come with brackets to allow multiple mounting configurations: flush-mounted, angled flush-mounted (approximately 10°), and angled surface-mounted (approximately 15°).

Tweeter Dimensions:

  Flush Mount Angled Flush Mount Angled Surface Mount
Mounting Height 0.238" 0.563" 1.272"
Depth 0.532" 0.612" 0.554" (screw depth)
Frame Diameter 1.976" 1.976" N/A
Cutout Diameter 1.57" 1.587" N/A
Frame Width N/A N/A 1.688"
Frame Length N/A N/A 1.897"

Crossovers: The component system includes passive 2-way crossover networks for a seamless transition between the woofers and tweeters. The slope is 12dB per octave (both high pass and low pass) and the crossover point is 4000 Hz. A switch on each crossover allows you to set the tweeter output; 0 dB, +3 dB, or +6 dB. The crossovers' input and output wires are attached; the woofer output has quick slide terminals that connect directly to the woofer and the tweeter output has bullet terminals that mate to the terminals on the tweeter wires. The crossovers' dimensions are:

  • Length: 4.595"
  • Width: 2.463"
  • Height: 1.004"

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.

Staff Reviews

Product reviews from the Crutchfield Labs

Kicker's Yellow Series of amps, speakers and subs gives you the performance you expect from Kicker at a more affordable price. This year's models are better than ever.

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Q & A

Customer Q&A

Crutchfield asked  
Why did you buy this?

Kicker has a good name and I wanted a decent component set for my front doors. [ Matthew  Mar 10, 2017 ]
Great component speakers! [ Christopher "CR  Dec 13, 2016 ]
christmas present [ richard  Dec 02, 2016 ]
Upgrade pioneer speakers [ JAVIER  Sep 25, 2016 ]
recomended by Crutchfield advisor [ Steven  Sep 05, 2016 ]
Andy, from Crutchfield, suggested these speakers. I've also heard good things on car forums about these speakers. Andy's Bio: [ VTengineer  Aug 17, 2016 ]
Kicker drivers sound great. [ B  Jun 28, 2016 ]
wanted to try some components :) [ Brandon  May 18, 2016 ]
Kicker makes great products. [ Anthony  Apr 26, 2016 ]
should work with my setup. reviews seemed good and cant beat the price or reliability of kicker products. [ cody  Apr 13, 2016 ]
Replacement speakers for my work truck [ Charles  Mar 11, 2016 ]
To replace the factory speakers. [ Jason  Feb 17, 2016 ]
Because it was a 6x8, and that is what I am replacing [ Robert  Feb 06, 2016 ]
small upgrade to my mustangs sound system...nothing fancy [ Francis  Feb 03, 2016 ]
These have a really good rating and fit perfectly to my car [ Jonathan P.  Dec 11, 2015 ]

5 questions already asked

Yes, they are rated to 75 Watts RMS. You'll be fine. [ GREG  Aug 09, 2016 ]
Yeah they'll run and sound clean but you'd be better off running them off an amplifier. [ Ryan  Aug 07, 2016 ]
Yes. I'm using them in my 2006 Ford F-150 with a Kenwood KDC-HD545U that provides 22 RMS X 4. They have good clarity and provide good mids and highs. Prior to buying them I read that they don't provide a lot of bass, so I added a powered sub. I'm happy with the sound. I have noticed some distortion above receiver volumes of 90%, but I don't believe this to be due to the speaker since the speakers can handle 75 RMS and my receiver provides up to 50 RMS. I found that the lowest of the three crossover tweeter settings provided plenty of highs. I doubt you would have to increase the setting. Hope this helps! [ Mike  Aug 05, 2016 ]
Bad crossover. When I bought mine. The crossovers where bad. Sent them back to Crutchfield and they replaced them quickly. New speakers worked just fine. [ TERESA  Dec 27, 2015 ]
If you purchased the product from Crutchfield, feel free to contact our Tech Support team. They can walk you through the connections on the product and see if there may be a fix. Our toll-free Tech Support number is printed on your invoice, and is also available under the "My Orders" tab in the "My Account" section of our website. If you did not purchase the unit from Crutchfield, then you may want to contact the manufacturer. You can also post your question in our forums: Or try our online support center: [ Kenny  Dec 26, 2015 ]  Staff
I put two pairs of these speakers in my 2013 F250 (front door and rear pillars as it is a crew cab). Sound great. I think two sets are better to balance the sound. [ WARREN  Dec 29, 2014 ]
Yes. Most definitely. These speakers have an awesome sound. [ BRUCE  Dec 29, 2014 ]
One in the front should be enough, just put some good speakers in the back but they aren't wor the extra money to use in the rear also, they are amazing in the front though [ DANIEL  Dec 29, 2014 ]
I put 2 sets in my truck and in my wife's SUV. I don't like for all the sound to be in the front. I hate if I'm in the back seat of a car and it sounds like the words are coming from the front. I think having them in the front and rear makes for equal sound and in my truck I have a 12 in sub, so it keeps the words and the mid notes from being covered up by bass. Hope that helps. [ THOMAS C  Dec 29, 2014 ]
Thanks for your question. For information on selecting the best amp I would recommend reaching out to an Advisor by phone (1-800-324-9695) or online chat. They will be able to help determine the differences between the amp models and help you make the best choice for your system. [ Krissy  Aug 25, 2014 ]  Staff
I agree with Mark, surface mount them. [ BRUCE  Dec 29, 2014 ]
1.57" for surface mount. [ MARK  Apr 25, 2014 ]
This will depend largely on your vehicle. For details on 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 what you will need for an installation. [ Krissy  Apr 21, 2014 ]  Staff