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Infinity Kappa 90csx

Kappa Series 6"x9" component speaker system

Item # 108K90CSXM

Infinity's reputation is legendary, but their Kappa Series car speakers don't rest on those laurels.

Find what Fits your vehicle

Infinity's reputation is legendary, but their Kappa Series car speakers don't rest on those laurels.

California customers:
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Discontinued item
12 questions - 23 answers

Item # 108K90CSXM

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About the Infinity Kappa 90csx

The legend continues...

Infinity's reputation is legendary, but their Kappa Series car speakers don't rest on those laurels. Designed and built for audiophile tastes, this Kappa 90csx 6"x9" component speaker system benefits from a refined design, Infinity's proprietary technology, and premium materials to deliver uncompromised audio quality.

The legend continues...

Infinity's reputation is legendary, but their Kappa Series car speakers don't rest on those laurels. Designed and built for audiophile tastes, this Kappa 90csx 6"x9" component speaker system benefits from a refined design, Infinity's proprietary technology, and premium materials to deliver uncompromised audio quality.

Edge-driven dome tweeters

Infinity employs an edge-driven design in their soft dome tweeters for a smoother, more open response and minimal distortion at high volume. Prepare for a more clearly defined soundstage and marvel as your music seems to come alive across your dash.

Woofers enhanced with Plus One+ technology

Bring on the bass. Kappa's glass fiber woofer will hold its shape when the power's cranked up, so you still get punchy and defined bass. Glass fiber weighs less than traditional materials, so you don't need a ton of power to drive this woofer either. Infinity's Plus One+ woofer technology extends the cone right up to the edge of the basket, giving you lots of surface area — and a bigger cone means more bass to complement the superior high-frequency response.

Premium crossovers

Infinity holds their external crossovers to the same standards as the rest of this speaker system. Premium components shape the distinctive Kappa sound and bring out all the details that make your music sound real.

These crossovers will easily accommodate an upgrade to a 3-way system if you'd like to add Infinity's optional Kappa 20mx 2" midrange drivers.

Awesome power handling, no matter the system

These 2.5-ohm speakers boast ultra-high sensitivity so that you can power them with a factory radio or aftermarket stereo, but we recommend feeding them plenty of power from an outboard amp — up to 135 watts RMS. Either way, these speakers' low impedance safely takes advantage of every watt of power available for exceptional performance. Enjoy Kappa sound quality at any volume. Grilles are included.


Product highlights:

  • component speaker system includes 2 woofers, 2 tweeters, and 2 external crossovers
  • 6"x9" Plus One+ glass-fiber woofer cone with hi-roll rubber surround
  • edge-driven, soft dome tweeter
  • 2.5-ohm impedance
  • handles up to 135 watts RMS (405 watts peak power)
  • frequency response: 35-35,000 Hz
  • sensitivity: 94 dB at 2.83 volts
  • woofer top-mount depth: 3-3/16"
  • grilles included
  • warranty: 3 years
  • Our 60-day money-back guarantee

What's in the box:

  • 2 Woofers
  • 2 Tweeters (each has attached 6" speaker leads with male quick-slides)
  • 2 Woofer grilles
  • 2 Grille frames
  • 2 Woofer bottom mount brackets
  • 2 Crossovers
  • 2 Flush-mount cups
  • 2 Threaded flush-mount adapters
  • 2 Plastic locking nuts
  • 2 Surface-mount cups
  • 2 Starfish tweeter mounts
  • Eight 1-1/2" Allen head screws
  • 3mm Allen head bit
  • Eight 1-3/8" Screws
  • Six 1/2" Flat head screws
  • Two M4x10mm Machine screws
  • 2 Washers
  • 16 Speed clips
  • 2 Adhesive backed Infinity logo badges
  • 2 Adhesive backed foam gaskets
  • Template on box
  • Installation manual

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More details on the Infinity Kappa 90csx

Pat M.

Features & specs

Speaker Size 6X9
Design 2-way
Tweeter Design Edge-Driven Dome
Impedance (Ohms) 2.5
Tweeter Composition Textile
Woofer Composition Glass Fiber
Woofer Surround Rubber
Parts Warranty 3 Years
Labor Warranty 3 Years
Sensitivity (1W at 1 meter) N/A
Sensitivity at 2.83 volts 94
Frequency Response 35 - 35k Hz
Minimum RMS Wattage ---
Maximum RMS Wattage 135
Peak Power Handling (Watts) 405
Top-mount Depth (Inches) 3 3/16
Bottom-mount Depth (Inches) 3 7/8
Cutout Diameter or Length (inches) 0
Mounting Height (Inches) 0.402
The Infinity Kappa 90csx replaces these items:

Product Research


Plus One Woofer Cones: The Plus One woofer cones offer more surface area than other speakers that fit in the same size opening. This is accomplished by using a new basket design and hi-roll surround. The result is greater bass output and an increase in efficiency.

High-Output Design: The high output 2.5Ω voice coil design compensates for the high in-line resistance of small gauge factory wiring and extracts every watt from factory receivers, increasing overall system output and efficiency (relative to 4Ω speakers). The speakers also benefit from increased power when you upgrade the wire and add aftermarket amplifiers, designed to power a 2.5Ω load.

Woofer Terminals: The woofers' input terminals are set screws that will accept up to 12 gauge bare wire.

Edge Driven Tweeters: The edge-driven tweeters use textile soft domes. An edge-driven tweeter has better dispersion characteristics and allows for a lower crossover frequency than typical tweeters of the same size, which improves imaging, vocals and musical clarity.

Tweeter Mounting: The I-Mount tweeter mounting system and Starfish mounting brackets give you several different ways to mount the tweeters:

  • I-Mount Tweeter Mounting System: The tweeters can be surface or flush mounted with Infinity's innovative I-Mount system:
    • Surface Mount: Surface mounting the tweeters involves screwing the surface-mount cup to the mounting location, then inserting and locking the tweeter into the cup.
    • Flush Mount: Flush mounting is made easy through the use of the threaded flush-mount adapter and plastic locking nut. Once a cutout is made, the flush-mount adapter (with the tweeter installed) is inserted into the hole. The large plastic locking nut is threaded onto the adapter (from behind the mounting surface) to hold the complete assembly securely in place. When flush mounted, the tweeters may be angled for optimum response and imaging.
  • Starfish Mounting Brackets: The Starfish mounting brackets allow the tweeters to be installed in factory locations behind the grilles:
    • Surface Mount (behind grille panel): Once the Starfish bracket is trimmed, it is screwed to the mounting surface behind the grille panel. Then, the tweeter is inserted into the bracket and locked into place.
    • Flush Mount (behind grille panel): Once the Starfish bracket is trimmed, it is dropped into the cutout in the mounting surface behind the grille panel. Then, the tweeter is inserted into the bracket and locked into place.
    • Bottom Mount (to grille panel): Once the Starfish bracket is trimmed, it is secured to the underside of the grille panel. The tweeter must be inserted into the bracket and locked into place before the bracket is mounted.

Tweeter Mounting Dimensions:

  I-Mount Surface Mount I-Mount Flush Mount Starfish Surface Mount (behind grille panel) Starfish Flush Mount (behind grille panel) Starfish Bottom Mount (to grille panel)
Mounting Height 0.860" 0.594" 0.861" 0.337" 0.0"
Depth 0.372" (screw depth) 0.750" 0.331" (screw depth) 0.601" 1.150"
Frame Diameter 1.618" 2.218" 1.661" 2.463" 3.260"
Cutout Diameter N/A 1.897" N/A 1.661" N/A

Crossovers: Each crossover has a tweeter output level switch; choose between flat and +3dB. They have screw terminal inputs and outputs that will accept gauge bare wire or spade connectors up to 0.315" wide.

Crossover Dimensions:

  • Diameter: 4-3/8"
  • Height: 1-3/8"

3-Way Upgrade: The system crossovers are gap-selectable, to accommodate a midrange upgrade. The optional 20mx midrange (item number 108K20MXM, sold separately) includes band pass crossover to upgrade this two-way system to a three-way system with perfect tonal balance.

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Customer Q&A

12 questions already asked

Do i need to have an amp?
[ Drake  Mar 03, 2022 ]
2 answers
No works good with factory head unit but it would help to have one. I do not have an amp and am pleased with the performance.
[ Jacob  Mar 03, 2022 ]
Yes. These speakers are not powered.
[ Perry  Mar 03, 2022 ]
what amp should i use if i have the 90 csx and the 60csx component speakers?
[ blake  Jan 11, 2022 ]
2 answers
I've had great luck with the Rockford Fosgate Prime amplifier. The Prime is a good bit cheaper than the Punch, but you get the wattage that you pay for, usually a bit more, when it comes to Fosgate's amps. My amp is 1ohm stable, but I noticed that these kappas are 2.5ohm where the kappas I bought were 1 ohm (3 way.. not component). As far as amplifiers go.. the most important features to me are first the quality, then the ohm. Sending 2ohm to your 2.5ohm kappas will be perfectly fine. The reason they did the "half ohm" is actually to compensate for the resistance of the length, gauge, quality, etc.. of your speaker wire. I would treat it as 2ohm like all the other brands would. Do yourself a favor and get a 2ohm Fosgate amp.. either Prime, or Punch if you've got the extra cash.
[ James  Feb 24, 2022 ]
I bought the Kenwood x8025 5 channel amplifier
[ JOSEPH  Jan 11, 2022 ]
Whats the difference between these and the kappa 693c?
[ Ernie  Jan 09, 2022 ]
1 answer
Thanks for your question. For information on comparing two or more models 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 and help you make the best choice for your system and your budget.
[ Kenny  Jan 11, 2022 ]  Staff
2020 Ram 2500 has 6x9 in all 4 doors and this says these won't fit?
[ Adam  May 16, 2021 ]
3 answers
I had this issue with Kappa 6x9's in my 2004 for the front doors. Not only the depth, but the actual hole in your metal frame will not be large enough to fit it. Right at the point the magnet is in.. the cage will get stuck about where the terminals are. I wanted these specific speakers and nothing less, though.. and I worried that cutting into the opening to make the hole larger would still leave me with a depth issue. So what I did was I got two Metra 6x9 adapter plates (it negates about 2" of the speaker's depth), then I took a box cutter and cut a hole in the door panel's factory grill. Then I installed a 6x9 foam baffle between the speaker and the adapter (before installing adapter) and marked/drilled 4 mounting holes around the cut hole. Then.. instead of screws I used thick machine screws with a large washer, lock washer and nut behind the panel to prevent screws from working their way out. It was worth it, but after doing both front doors.. I ordered two 6.5" kappas for the rear doors and used crutchfield's included adapter plates. They went in much easier, but they were so nice looking that I went ahead and cut into the back panels regardless.. if for nothing else than the aesthetics.. plus it did allow me to access the crossover button on the tweeter. I bought the 3 way kappas instead of component, but now I've bought a 2010 and am getting the same exact speakers just component rather than 3 way. I know it's not very appealing to many.. cutting into a door panel.. but I'm not sure exactly how much space is between the mounting hole of the frame and the inside of the door panel. It's possible to find an adapter that spaces the speaker out from the frame just enough that no cutting into the frame is needed and also doesn't press into the door panel. Also.. I think the component speakers may be about 1/2" less in depth than the 3 way version due to the amount that the 3 way's tweeters stick out past the speaker's surround.
[ James  Feb 24, 2022 ]
Hey, I have a 2020 Silverado with 6x9s in all 4 doors and these fit fine in mine. Bought them last year and they work great, only ones that don't fit are the corner speakers. They sit pretty tall and the covers won't go back on so I didn't install them. Gonna have to customize them a bit to fit. Other than that I didn't have any issues. They don't send any instructions or anything when you order them, but the speakers are way better than stock.
[ IAN  May 17, 2021 ]
It's because of the depth of the speakers. You'll have to make modifications to get them to fit.
[ JASON  May 16, 2021 ]
What does the button in the center of the crossover do??
[ Stephen  May 09, 2021 ]
3 answers
Increase tweeter output+-3db
[ P  May 09, 2021 ]
pretty sure it boosts or lowers treble slightly.
[ THOMAS  May 09, 2021 ]
Pretty sure it boosts or decreases treble slightly.
[ THOMAS  May 09, 2021 ]
Does a 2.5 olm speaker run on an amplifier on 2olms or 4 olms? I've read matching olms is preferred
[ Mike  Mar 05, 2021 ]
1 answer
The amplifier will need to be 2 ohm stable. You can always run higher resistance speakers than what the amp is rated for, but not lower. I run mine on an Alpine PDR-V75. Sound great.
[ Brian  Mar 05, 2021 ]
can I connect the woofer only? Wire it directly or use the crossover without connecting the tweeter?
[ Edward  Nov 19, 2020 ]
2 answers
Use the crossover
[ CYNTHIA  Nov 19, 2020 ]
You can do either one. I am running the 3 way crossover with the extra mids.
[ MARK  Nov 19, 2020 ]
will these fit in a 1988 BMW 735i?
[ AbleTwo  Jul 14, 2020 ]
1 answer
Sorry but no. The 1988 BMW 735i has 5 1/4 inch speakers front and rear accompanied by 1.5 inch tweeters. I put 90csx set in my 2016 Honda civic but it was a fully custom modified job. Simplest way would be to purchase a nice component set with the 5 1/4 inch speakers.
[ Jeffrey Lynn  Jul 15, 2020 ]
What's the exact dimensions of just the tweeter because I want to get tweeter pods for them?
[ Daniel  Jun 15, 2020 ]
1 answer
The dimensions of the tweeter without any mounting gear are 1.413" diameter and 0.716" tall
[ Paul  Jun 30, 2020 ]  Staff
Have a 2016 honda pilot was looking for some have a great speakers from the factory would the speakers be a good fit in the 2016 honda pilot?
[ Junior  Jun 10, 2020 ]
1 answer
Was yours the EX, LX or Touring edition? We don't show that any of those versions had 6x9" factory speakers. You would have to make modifications to install those. You might be better off going with a 6 1/2" speaker. You can connect with one of our friendly product advisors to see which speakers are the best fit for your Honda here:
[ Cosmo  Jun 24, 2020 ]  Staff
How do you open the crossovers? White dots in the middle turned left or right, won't open.
[ Gabriel  May 20, 2020 ]
4 answers
the dots show you where to put the cover back on at. match the dots and put the cover on..To get the cover off , make sure the dots do NOT line up and push a small screwdriver through the mounting hole in the back and the cover comes off easily.
[ Steven  Apr 22, 2021 ]
You don't open up the go button you takeoff the black cover
[ MELVIN  May 20, 2020 ]
I remember having an issue getting the covers off my crossovers as well. If I recall correctly, it was a "twist & pull". I may have implemented a flat screwdriver in the first one to help pry it off. Then I saw how it worked, and the second cover was a piece of cake.
[ JOHN  May 20, 2020 ]
Turn counter clockwise to open.
[ MARK  May 20, 2020 ]
Can you please tell me the mounting depth of the flush-mount adapter for the tweeter? I didn't see this dimension in the owner's manual. Thank you.
[ Ron  Sep 24, 2019 ]
2 answers
The mounting depth needed with using the I-mount flush mount adapter is 0.75"
[ Paul  Oct 09, 2019 ]  Staff
Well... I fortunately have not installed them yet.. I pulled the tweets and the static mounts are surface mount, the swivel mount requires a hole but depending on the thickness of the panel is a Max of 0.4 inches. Should not be an issue in 95%+ of vehicles...
[ Richard  Oct 08, 2019 ]

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