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Infinity Kappa 603CF

Kappa Series 6-1/2" component speaker system

Item # 108K603CF

This Kappa 603CF 6-1/2" component speaker system benefits from a refined design, Infinity's proprietary technology,...

Find what Fits your vehicle

This Kappa 603CF 6-1/2" component speaker system benefits from a refined design, Infinity's proprietary technology,...

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Item # 108K603CF

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$299.95 -$15.00 Outlet savings


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About the Infinity Kappa 603CF

Alexander H.

Kappa quality

Infinity designed and built their Kappa Series for audiophile tastes. This Kappa 603CF 6-1/2" component speaker system benefits from a refined design, Infinity's proprietary technology, and premium materials to deliver uncompromised audio quality. Plus, Infinity has added convenient features for getting just the right sound for your ride.

Kappa quality

Infinity designed and built their Kappa Series for audiophile tastes. This Kappa 603CF 6-1/2" component speaker system benefits from a refined design, Infinity's proprietary technology, and premium materials to deliver uncompromised audio quality. Plus, Infinity has added convenient features for getting just the right sound for your ride.

Edge-driven silk dome tweeters

Infinity employs an edge-driven design in their silk dome tweeters for a smoother, more open response and minimal distortion at high volume. With a frequency response that peaks at 40,000 Hz, you'll have what you need to hear a new level of detail in the car. Dial in your sound even more and adjust the tweeter level using the control button on the separate crossovers.

Plus One+ woofer technology

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.

Awesome power handling, no matter the system

These 3-ohm speakers boast ultra-high sensitivity so that you can power them with a factory radio or aftermarket stereo, but you'll get your best results feeding them plenty of power from an outboard amp. 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 not included. Factory grilles will be suitable for most installations.


Product highlights:

  • component speaker system includes 2 woofers, 2 tweeters, and 2 external crossovers
  • 6-1/2" Plus One+ glass-fiber woofer cone with hi-roll rubber surround
  • edge-driven, silk dome tweeter
  • 3-ohm impedance
  • handles up to 110 watts RMS (330 watts peak power)
  • frequency response: 45-40,000 Hz
  • sensitivity: 93 dB at 2.83 volts
  • woofer top-mount depth: 2.114"
  • cutout diameter: 5.128"
  • grilles not included
  • warranty: 3 years
  • Our 60-day money-back guarantee

What's in the box:

  • 2 Woofers
  • 2 Tweeters (each has a 6" speaker lead attached terminated with male quick-slides)
  • 2 Woofer adapter brackets
  • 2 Crossovers
  • 2 Threaded flush-mount cups
  • 2 Plastic locking nuts
  • 2 Surface-mount cups
  • 2 Starfish mounts
  • Eight 1-1/2" Allen head screws
  • 3mm Allen head bit
  • Eight 1-3/8" Screws
  • Eight 1/2" Screws
  • Six 3/8" Flat head screws
  • 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 603CF

Pat M.

Features & specs

Speaker Size 6 1/2
Design 2-way
Tweeter Design Edge-Driven Dome
Impedance (Ohms) 3
Tweeter Composition Silk
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 93
Frequency Response 45 - 40k Hz
Minimum RMS Wattage ---
Maximum RMS Wattage 110
Peak Power Handling (Watts) 330
Top-mount Depth (Inches) 2 1/8
Bottom-mount Depth (Inches) 2 1/2
Cutout Diameter or Length (inches) 5 3/16
Mounting Height (Inches) 0.564
The Infinity Kappa 603CF 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.

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

Mounting Applications: These speakers are marketed as 6½"; they will fit in many standard 6½" speaker openings (just over 5" diameter), but do not use the standard 6½" speaker bolt pattern. In order to install the woofers in standard 6½" speaker openings you must drill new screw holes. If new holes are drilled in the mounting surface of the car, no bracket is needed. If drilling in the car is not an option, the included brackets can be used, which have standard 6½" mounting holes and the Ford non-symmetric four hole pattern, as well as other non-standard patterns. When using the brackets the depth becomes 1.884" and the mounting height becomes 0.794".

High-Output Design: The high output 3Ω 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 3Ω load.

Edge Driven Tweeters: The ¾" edge-driven tweeters use silk 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. The result is improved vocals and musical clarity. The 6" speaker wire attached to each tweeter is terminated with male quick-slides (0.187" positive and 0.110" negative).

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)
    • Flush Mount (behind grille panel)
    • Bottom Mount (to grille panel)
    • Flush Mount (in-dash location)

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) Starfish Flush Mount (in-dash location)
Mounting Height 0.898" 0.354" 0.898" 0.367" 0.0" 0.062"
Depth 0.34" (screw depth) 0.531" 0.34" (screw depth) 0.531" 1.062" 1.0"
Frame Diameter 1.615" 1.811" 1.656" 2.568" 3.258" 3.258"
Cutout Diameter N/A 1.610" N/A 1.656" N/A 2.828"

Crossovers: The input, tweeter output, and woofer output wires are attached to the crossovers; each is 8" long and terminated with tinned bare wire. Each crossover has a tweeter output level switch; choose between flat and -3dB. Each also has a 2-way/3-way switch used when adding the matching midrange to upgrade the system to 3-way.

Crossover Dimensions:

  • Width: 4⅛"
  • Height: 1"
  • Depth: 1⅞"

3-Way Upgrade: The included system crossovers are gap-selectable, to accommodate a midrange upgrade. The optional Kappa 203S and 303S midrange (item numbers 108K203S and 108K303S, both sold separately as a pair) include the 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

5 questions already asked

What amp should I use?
[ MIGUEL  Jun 11, 2022 ]
1 answer
We'll be happy to help you select a new amp for these speakers, but we'll need more info before we can make a recommendation. Our advisors are happy to help at 1-800-324-9695.
[ ZACHARY  Jun 11, 2022 ]  Staff
Can this work in my jeep liberty 2008?
[ alyph  May 28, 2022 ]
1 answer
Good Evening Alyph, thank you for reaching out to us and that is a great question. Those Infinity Kappa 603CF would indeed fit in your 2008 Jeep Liberty.
[ ARIELLE H  May 29, 2022 ]  Staff
Best quality speeker Infinity performance?
[ TomCat  Nov 19, 2021 ]
3 answers
They sound great with basic factory power, sound way better with added small amp(45 watts per channel).
[ STEPHEN P  Nov 19, 2021 ]
I have not purchased infinity car speakers before and let me tell you. I WAS BLOWN AWAY! These are super efficient and play with clarity even at higher levels.
[ ANDREW  Nov 19, 2021 ]
They sound great
[ RAY  Nov 19, 2021 ]

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