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Infinity Kappa 63.7i

6-1/2" 3-way car speakers
For 6-1/2" and 6-3/4" openings

Item #: 108637I

13 Reviews

This item is no longer available.

Original Price: $69.99 pair

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Infinity Kappa speakers incorporate the latest technology to provide you with outstanding sound reproduction. And, thanks to Infinity's innovative low-impedance design, they're built for high efficiency as well.

The Kappa 63.7i 6-1/2" speaker features a super-stiff woofer cone to minimize flexing that can cause distortion. The Plus One cone offers a larger surface area than other 6-1/2" speakers, for improved bass output and efficiency. The woofer's powerful, compact neodymium magnets weigh much less than traditional magnets — a nice feature when you're trying to save weight in your high-performance vehicle.

Infinity incorporates an Emit ribbon tweeter for brilliant highs, and adds an M.M.D. midrange to reproduce the vocals in your music just the way they were recorded, with minimal coloration or distortion.

The computer-optimized outboard crossover employs audiophile-grade components to separate highs and lows so that the woofer and tweeters work together perfectly. A tweeter level control allows you to tailor the tweeters' response for perfect balance.

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

Product Highlights:

  • 3-way car speakers for 6-1/2" and 6-3/4" locations (pair)
  • 2-ohm impedance for extra power (compatible with all factory or aftermarket car stereos)
  • Plus One woven-glass-fiber woofer cone with rubber surround
  • EMIT tweeter and M.M.D. midrange
  • computer-optimized outboard crossovers with tweeter level control
  • power range: 2-75 watts RMS (225 watts peak power)
  • frequency response: 45-25,000 Hz
  • sensitivity: 95 dB
  • Intermount III mounting system for fit in 6-3/4" openings
  • top-mount depth: 2"
  • warranty: 3 years
  • Our 60-day money-back guarantee

Why replace your car's original speakers?

The speakers that originally came in your car were made from inexpensive materials, designed to create acceptable sound at the lowest possible cost to the manufacturer. If you love music, you deserve better. Name-brand aftermarket speakers deliver fuller, richer sound with considerably more detail and nuance, and they're capable of playing louder and cleaner than factory speakers. Connect new speakers to your factory radio and you'll get the best possible sound from your dealer-equipped system. Pair them up with a new car stereo for a level of enjoyment that can rival a high-fidelity home audio experience.

Infinity Kappa 63.7i Reviews

Average Customer Review:

13 Reviews

Very nice - a little harsh

Written by: Korey from Olathe, KS on August 25, 2009

2008 Ford Explorer Sport Trac
Crutchfield Customer Review (What's this?)

I purchased these speakers for the Front when they were on clearance. They sound good for the money I paid. Some may think the highs are a little harsh, but I like the sound of crisp highs. I would never pay retail for these. If you can't get these on clearance, I would recommend a true component set. These are not much easier to install due to the separate crossover. I would prefer an integrated (on board) crossover for a coax. That's the whole point of buying a coax -- for the ease of installation. Otherwise, they can't compare to separates (components).



Infinity Kappa 63.7i

Written by: Dan from Rapid City SD on December 8, 2008

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

After the foam surrounds on the door speakers deteriorated in our 1998
Jeep Grand Cherokee with Infinity sound system I replaced them with two
pair of Infinity Kappa 63.7i . The sound was much improved with good
amount of decent bass for not having a subwoofer. The mid and high
tones are very clear. This is run off the factory amplifier that I believe is
30X4 watts.

There was some installation problems that were incurred. While the
fitment guide says they fit, the tweeter pedistal contacted the grille on the
front doors. My solution was to adjust the grilles with some gentle
hammering to provide minimum clearance. Overall I'm pleased with these



too much plastic

Written by: daniel from cumberland ky on September 1, 2008

Crutchfield Customer Review (What's this?)

speakers have a good techno sound might be worth the money after the price break but certainly not before will see how long they last before the cones give out!



Great mids and highs, but where's the bass?

Written by: Will from Austin TX on August 8, 2008

I installed these speakers in the front doors of my 2008 Prius (2 ohm JBL amp). The mids and highs are outstanding, but the bass totally bites. I can understand if a speaker can't quite handle deep bass, but these speakers actually make weird noises with heavy bass (like they are bottoming out, makes a "thud" on every beat). Anyway, I pulled these out and replaced with Polk 2-ways...the Polks sound 90% as good and can put out some real bass with no distortion. Infinity should have put a bass blocker or better crossover, or used regular magnets instead of neos...



Good Speakers, not Great Speakers

Written by: Zermelo from Bayside, NY on July 26, 2008

I purchased these speakers after careful consideration along with a pair of 693.7i Kappas.

These are good sounding speakers, especially the high end. The highs are crisp and bright and not tinny as some have described, and the mid-range vocals sound clear and present. That being said, do not expect door pounding bass from these speakers,
but this should NOT be expected from 90% of multi-element 6.5" free air speakers. Solid bass only comes from well designed enclosures from dedicated drivers.

However, if you take the time to dynamat your front door panels and make sure to make a good seal between the speaker and door panel, these can produce decent mid bass.

Also note that I am powering these with a amp which give 250 RMS x 4 watts at 2 ohms so the speakers are getting more than enough power to
drive them to their potential.

The 2 ohm rating is accurate as they were noticeably
louder than my previous 6.5"s rated at 4 ohms. Also
installation was fairly easy, the mounting brackets
made the install quite easy, and because of the small magnet size, space wasn't an issue.

The worst part was placement of the overly large
crossovers. Get yourself some adhesive velcro and
stick them in an appropriate place.

If you have and amplifier and listen to rock, classical,
or jazz, then you should be pleased with these speakers. If you listen to hip hop or Reggae, then don't expect clear pounding bass - you will have to
get a subwoofer.



Infinity Kappa 63.7i

Written by: sansone from Hillsborough NJ on June 28, 2008

Crutchfield Customer Review (What's this?)

Great Sounding SPeakers! Definitely improved the sound in my Scion Xb, especially up front, where I had replaced Scion factory stock speakers, which are just so inferior in general. Definitely better midrange, tighter bass and highs. You will definitely love these speakers.

If you do install these in the 08 xB, just be aware that the cutouts in the front door are larger than normal, and you will need to use the brackets that come w/ the infinity and drill new holes. You will also have to seal around the edges of the brackets/door panel, as they are just barely large enough to cover the opening. The crutchfield adapter brackets are even a bit smaller.



Clean crisp sound

Written by: Deke from Nova Scotia, Canada on February 11, 2008

I purchased these after hearing them in a friends car, I purchased them and put them in the doors of and intrepid along with the 6x9's infinity693.7i for the back, the sound is truely amazing, clean and crisp mids and highs, I also suggest as others mentioned that you hook them up to a four channel amp and not the head unit as they are 2 ohm's, you'll think you have a high end home stereo speaker in your car, I'm very pleased with infinity sound and quality, I never purchase infinity product before, I'm very glad I did. I'm now thinking of purchasing a ten inch infinity sub for just a little thump.



Sweet 3-Ways

Written by: No from Miami Lakes, FL on December 15, 2007

After adding Kappa components upfront and hearing how great they sound... I decided to upgraded to these Kappa 3-Ways in the rear of my 06 Rav4... These speakers are absolute Heaven with Crystal clear highs, and Great mids... I have a Kappa 12" sub in the back for lows... Infinity has found a new life customer...



Awsome speakers....even better service

Written by: Gabe from Lafayette,LA on June 9, 2007

Crutchfield Customer Review (What's this?)

I have a 06 Titan with the rockford fosgate system, which all 12 speakers are 2 ohms, so I purchased these for compatibility...WOW!! The sound diference was excruciatingly better before I switched the tweeter DB.
But Crutchfield didn't send a sheet to show me how to take apart the jig-saw-puzzle of a door to get to the I called custermer support, and the guy actually tracked down the blueprints of my truck(they did not have a build sheet on file) and stayed on the phone the entire time I disassembled my truck(which was VERY complicated...thanks Nissan!). The customer service is unbeatable in any industry!! These guys go extremely out of their way to make sure your happy...even after the sale.I am now an Infinty fan, but a life long customer!! You cant go wrong with crutchfield! Oh yeah, the speakers are PERFECT!!



Crystal Clear

Written by: Bill from Mount Airy, MD on April 20, 2007

2005 Saturn ION 3

I bought a set of these and a set of the kappa 2-ways since these won't fit on the rear deck of my Saturn Ion Redline. I have them hooked up to a sony 4-channel amp pumping 60W to each at 2 ohms. They sound beautiful even at volumes high enough to compete with my 2 alpine type-R 12s.



Crisp and Clean

Written by: Carl S. from Modesto, California. on December 26, 2006

I had polk momo's in my front door panels, but they just wern't bright enough.
I heard these, and had to have a pair.
They are simply put, the brightest, crispest, smoothest speakers I've ever owned.

If you're on the fence about buying them, get off.
They are well worth the money.



1995 Saturn SC1

Written by: Nagle from Bensalem, PA on June 23, 2006

All I was looking for in a 6.5" speaker was to fill out the highs and mids for my front door kick-panel. Let me say this, they are very crisp and have great mids and highs. Typically I only use Hifonics speakers because they are the best, for bass. I heard some Infinitys in a friends car and was very impressed by the clarity of the highs and mids. If your looking for a bass monster, look elsewhere, but if your interest in some fantastic sounds if you already have subs, these will do the job. Try not to run them straight off your head unit, get an amp to push these puppies. I must say that I'm going to use Infinity for clear highs and Hifonics for everything else. I've just become an Infinity customer after buying these.



Infinity Kappa 63.7i

Written by: Doug from Indianapolis, IN on November 20, 2005

I installed the 63.7i's in the rear doors of my Toyota Prius and added an Infinity Reference 7521a amp for extra power and presence. I also installed Dynamat around the speakers and I have not experienced any rattling, vibration or distortion when I crank up the volume. Very clean, quality sound which makes my long commutes much more enjoyable.



Hands-on research

What's in the box?

Download owner's manual

  • Two 3-way speakers
  • 2 Grilles
  • 2 Grille rings
  • 2 In-line crossovers (each crossover has 11" input leads and 18" output leads)
  • 2 Metal 6-1/2" adapter rings
  • 2 Plastic GM/Chrysler adapter brackets
  • Eight 1" self-tapping screws
  • Eight 1/2" self-tapping screws
  • 8 Machine screws
  • 8 Speed clips
  • Instructions
  • Warranty card

Product Research


Plus One Woven-Glass-Fiber Woofer Cones: The Plus One speakers use cones approximately 30% larger 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. The woven-glass-fiber material is very light and extremely stiff, minimizing cone flex. This results in very low distortion and improved clarity.

Motor Structure: The new Kappas use a Neodymium motor structure with an integrated heat sink. This design provides a massive amount of energy while minimizing mounting depth and magnet diameter. The integrated heat sink cools the motor structure efficiently, thus increasing power handling while reducing distortion.

Emit Tweeter and MMD Dome Midrange: Each speaker has an Emit tweeter and an MMD (Metal Matrix Diaphragm) dome midrange. The benefit is increased power handling and reduced distortion at high output. This technology also allows for better integration with the woofer. The tweeter has an adjustable output level, +0 dB (flat) and +3 dB.

SLI High-Output Design: This high output 2 ohm design extracts every watt from today's high powered receivers and amplifiers, increasing overall system output and efficiency (relative to 4 ohm speakers).

Crossovers: Kappa speakers include computer-optimized, voice-matched crossovers, using audiophile quality air core inductors and polypropylene capacitors.

Crossover Connections: Each crossover has a 11" input lead terminated with bare wire and two 18" output leads, one for the woofer and one for the tweeters, terminated with female quick-slides. The female quick-slides connect to the male quick-slides on the speaker. The positive terminal on the woofer input is 0.248" and the negative is 0.191". The positive terminal on the tweeter input is 0.205" and the negative is 0.109".

Crossover Dimensions: L=4.265", W=2.073", H=1.206"

Intermount III: Infinity's Intermount III mounting system allows the 63.7i speakers to fit a variety of 6-1/2" and 6-3/4" applications. Two adapter rings are included for each speaker.

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.