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Infinity Kappa 42.9i

4" 2-way car speakers

7 Reviews

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Item # 108429I

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Our take on the Infinity Kappa 42.9i

The Kappa 42.9i 4" speakers feature light, but stiff woven glass-fiber woofer cones that won't flex or distort. The Plus One design offers a larger surface area for improved low-frequency output and efficiency, while longer voice coils produce tighter, snappier midbass. Large magnets keep the woofers running cooler by placing more steel close to the voice coils to act as a heat sink.

Infinity built the latest Kappa speakers with improved technology and high-end materials to provide you with outstanding sound reproduction. The low-impedance design makes these speakers very efficient, so you'll get great results powering them with a factory or aftermarket stereo.

The Kappa 42.9i 4" speakers feature light, but stiff woven glass-fiber woofer cones that won't flex or distort. The Plus One design offers a larger surface area for improved low-frequency output and efficiency, while longer voice coils produce tighter, snappier midbass. Large magnets keep the woofers running cooler by placing more steel close to the voice coils to act as a heat sink.

Infinity uses the same Metal Matrix Diaphragm tweeter found in many of their popular home speakers, so you'll hear the music the way it was recorded with minimal coloration or distortion.

The computer-optimized outboard crossover networks employ audiophile-grade components to separate highs and lows, so that the woofer and tweeter work together perfectly. Pre-wired crossovers eliminate a time-consuming step in your installation, and terminals at the end of the crossover wires screw directly to the speakers, leaving no chance for incorrect wiring.

Important Note: These Infinity Kappa speakers use a low impedance design to pull more power safely from your car stereo or amplifier. This design is compatible with virtually all factory and aftermarket stereos.

Installation Note: These Infinity speakers do not include screws or speed clips. You may be able to use the factory screws to install them, but it's always a good idea to have an assortment of self-tapping screws (5/8" to 1") and speed-clips on hand.

Product Highlights:

  • 2-way 4" speakers (pair)
  • True Four Ohm Impedance technology: speaker's 2-ohm impedance combines with speaker wire impedance for a 4-ohm load
  • compatible with virtually all factory or aftermarket car stereos
  • Plus One® woven-glass-fiber woofer cone with hi-roll rubber surround
  • 1" edge-driven M.M.D.® dome tweeter
  • computer-optimized outboard crossover with tweeter level control
  • direct-connect crossover dongle
  • power range: 2-50 watts RMS (150 watts peak power)
  • frequency response: 75-25,000 Hz
  • sensitivity: 93 dB
  • top-mount depth: 1-7/8"
  • warranty: 3 years
  • Our 60-day money-back guarantee

What's in the Box:

  • Two 2-way speakers
  • 2 Grilles
  • 2 Grille rings
  • 2 In-line crossovers (attached)
  • 2 Adhesive backed foam gaskets
  • Instructions
  • Warranty information

Featured Video:


Infinity Kappa 42.9i Reviews

Average Customer Review(s):

(7 Reviews)

Kappa 6 x 8

TonyP from So Cal on 6/14/2012

Great sounding speakers when they stay on...worked for 1 week and then cut out. sub was still playing but no speakers. I guess these speakers need to be sheilded from the door metal, but that would still have soem of the power going to the speaker frame.

Pros: Good sound

Cons: For the cost they should make the connectiosn a little better, might og bought a different brand if I had known one or two of my new speakers woul dbe grounding out to the door...

great sound, minor issues.

adam c from woburn, ma on 5/20/2012

1997 Saab 9000
Crutchfield Customer Review (What's this?)

I purchased these for my saab 9000 and they do sound great with my alpine deck. after a week of working fine my deck came up with "dc error." Meaning that one of the speakers was grounding out. to my relief it was the front left, one of these 4"ers and not the 6x9's in the back which were a p.i.n.t.a to install. there was no obvious flaw in the speaker to be fixed so i coated the mount on the car with liquid electrical tape which i allowed to dry and then installed the speaker with nylon screws. That done, these speakers contribute to a great sound system. they are clear and accurate without being tinny, the kapa 6x9's in the back fill in the sound nicely and eventually i will install my sub and amp to really achieve full resolution.

Pros: great sound, easy to work with.

Cons: speaker grounded out as installed per the directions, but adapt and overcome i say.

4" infinity kappa

JeepJockRich from Cinnaminson, NJ on 4/1/2012

1998 Jeep Wrangler
Crutchfield Customer Review (What's this?)

I put the Kappa's on the back of my rollbar in my jeep wrangler using Verspods enclosures. They sound AWESOME !!!!! It really adds to the bass as well. I can totally feel the music. KATTY PERRY sounds so good now cruising with my top down. I now have a total of 12 Infinity speakers in my jeep and it sounds like a concert hall even with the top off at 65MPH.



Good if you have a subwoofer

Ben from Ripon, WI on 6/11/2011

1996 Saab 9000
Crutchfield Customer Review (What's this?)

I bought and installed these speakers, 6x9 infinity kappas, and a kenwood head unit in Aug '10. They installed ok (save for 1 major problem that I will get to) and sounded really good, except that the bass was just not there. I could turn up the bass output and bass boost from the head unit, but still it just lacked that little bit of bass. The major problem that I had with the setup was that the head unit would go into protect mode way too often. I had no idea why. Today I went to a local car stereo installer, the Exclusive Company, and they diagnosed the problem: Infinity Kappas will ground out when they are installed on a metal bracket. They told me that they have people come in all the time with Infinity Kappas and they always have the same problem. With the addition of a decent but not overpowering subwoofer in the trunk the setup of a matched set of Inifinity Kappas sounds AWESOME!



decent replacement part for old jeeps

DP from WRJ, Vt on 9/5/2010

1974 Jeep CJ5
Crutchfield Customer Review (What's this?)

I chose these strictly based on size, but they sound good for such a small diameter speaker. I put them in the dash of a '74 cj5. Had to modify the mounting a bit because the speaker's pattern is a bit short of the stock dash mounting studs. The chunky terminal block/crossover was a slight hassle in such a limited space.



great clarity

TRACY from miami fl on 1/19/2009

Crutchfield Customer Review (What's this?)

these speakers offer great clarity




Andrew from Marion, IA on 1/6/2009

The Kappa 42.9I's offer incredible sound reproduction, my car came factory with 2 pairs of 4" speakers and a pair of 8" woofers, when shopping for 4" speakers to replace the factory speakers I knew I couldn't go wrong with anything from Infinity's Kappa series. And I was right. Incredible highs and surprisingly good lows and mids. For pure enthusiasts looking for perfect imaging, consider getting a pair of these custom molded into your dash for a center channel effect, you CANNOT go wrong with the sound that these produce. Simply amazing.




Hands-on research

Features and Specs

Speaker Size
Design 2-way
Tweeter Design Dome
Impedance (Ohms) 2
Tweeter Composition MMD
Woofer Composition Woven-glass fiber
Woofer Surround Hi-roll rubber
Parts Warranty 3 Years
Labor Warranty 3 Years
Sensitivity (1W at 1 meter) N/A
Sensitivity at 2.83 volts 93.1
Frequency Response 75 - 25k Hz
Minimum RMS Wattage 2
Maximum RMS Wattage 50
Peak Power Handling (Watts) 150
Top-mount Depth (Inches) 1 7/8
Bottom-mount Depth (Inches) N/A
Cutout Diameter or Length (inches) 3 1/2

Product Research


Plus One Woofer Cones: The Plus One speakers use cones more surface area than other speakers of the same size. This is accomplished by using a new basket design and hi-roll surround. The Plus One design offers greater bass output and a significant increase in efficiency.

Woven Glass Fiber Woofer Cones: This woven-glass-fiber material is very light and extremely stiff, minimizing cone flex. This results in very low distortion and improved clarity.

Edge Driven MMD Dome Tweeters: Each speaker has an Edge-driven MMD (Metal Matrix Diaphragm) dome tweeter. The benefit is increased power handling and reduced distortion at high output. This technology also allows for better integration with the mid/woofer.

High-Output Design: The high output 2-ohm 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 4 ohm speakers). The speaker's 2.0-ohm impedance combined with the impedance of your speaker wire provides a true 4-ohm load to your connected headunit or amplifier. The speakers also benefit from increased power when you upgrade the wire and add aftermarket amplifiers, designed to power a 2-ohm load.

Crossovers: Kappa speakers include computer-optimized, voice-matched crossovers, using audiophile quality air core inductors and polypropylene capacitors. The crossover slope is 12 dB/octave.

Crossover Connections: Each crossover is connected to the speaker by a 6" wire. The input terminals are set screws that will accept up to 10 gauge bare wire.

Crossover Dimensions:

  • Length: 3-1/16"
  • Width: 1-1/4"
  • Height: 1-3/16"

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

Video: Infinity Kappa car speakers
by Robert Ferency-Viars

Infinity Kappa is Infinity's high-performance line of car speakers. They're designed and built to give you excellent sound, especially in an amplified system.

What are the Labs?