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Infinity 100.9w

Kappa Series 10" subwoofer with selectable 2- or 4-ohm impedance

19 Reviews | 5 questions - 7 answers

Item # 1081009W

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Our take on the Infinity 100.9w

Infinity Kappa subwoofers combine great-sounding bass with the wiring versatility you need to build a system that can expand to meet your changing needs. And these enhanced woofers feature superior construction that makes the thump come easy.

Infinity Kappa subwoofers combine great-sounding bass with the wiring versatility you need to build a system that can expand to meet your changing needs. And these enhanced woofers feature superior construction that makes the thump come easy.

The Kappa 100.9w 10" subwoofer features Infinity's unique Selectable Smart Impedance design, which lets you build exactly the system you want — high-power or multi-sub — without complicated wiring. Just flip the convenient impedance switch to safely choose between 2 or 4 ohms. If you're thinking about upgrading your amplifier or adding another sub down the line, this sub makes it easy to reconfigure — and it's nearly impossible to wire incorrectly.

This sub handles plenty of power and sounds great in sealed and ported enclosures, too. The coated glass-fiber cone offers remarkable rigidity that minimizes distortion, while the thick rubber surround promotes smooth excursion. Add the hefty cast aluminum basket to the mix and you've got proven delivery system for potent low end.

To drive this single subwoofer, we recommend a mono amplifier rated between 260 and 525 watts RMS at 2 ohms. For more information, please refer to our article on How to Match Subwoofers and Amplifiers.

Priced per speaker

Product Highlights:

  • 10" subwoofer with selectable 2- or 4-ohm impedance
  • coated glass-fiber cone with rubber surround
  • cast aluminum basket
  • frequency response: 25-400 Hz
  • power range: 50-350 watts RMS (1,400 watts peak power)
  • sensitivity: 89 dB
  • top-mount depth: 6"
  • sealed box volume: 0.75 cu. ft.
  • ported box volume: 1.5 cu. ft.
  • warranty: 3 years
  • Our 60-day money-back guarantee

If you are lucky enough to get one of these before they are gone do so. Very powerful and accurate response with a wide response range and great efficiency.

Mark K, Van Buren, AR

What's in the Box:

  • One 10" Woofer
  • Self-adhesive foam gasket
  • 3mm Allen wrench
  • Owner's manual (English/ French/ Spanish/ eleven other languages)
  • Technical data sheet
  • Warranty and on-line product registration information

Infinity 100.9w Reviews

Average Customer Review(s):

(19 Reviews)


Music is Life from murfreesboro, TN on 2/26/2016

I am currently not in the field anymore, but was for many years. These series of subwoofers are bare none the best value and actually the best performing subwoofers ever made by my standards. The sound quality and frequency response is absolutely phenomenal at proper wattage and if the novice was to over power them the coils would take the abuse although the sound would be distorted. The only flaw is that the mechanical bond between the rubber and the cone has a tendency to fail, but it is easily repaired with super glue and anyone with an I.Q. of 80 or better can make the repair. I wish they never discontinued the all aluminum cone for this model because it was almost indestructible. in fact, I have yet to hear of a cone ever failing. I even have seen them get wet and survive. It was a flawless design and should have been their flag ship to dominate the car audio subwoofer market.

Pros: Beast of a sub

Cons: Cone to rubber bond

High performance response

Mark K from Van Buren, AR on 5/28/2015

Crutchfield Customer Review (What's this?)

If you are lucky enough to get one of these before they are gone do so. Very powerful and accurate response with a wide response range and great efficiency.

Pros: Every specification.

Cons: None

infinity 100.9w

Ted from Marshall MI on 4/16/2014

Crutchfield Customer Review (What's this?)

This hit very hard love them



best sub ever

jake from cadott, wi 54727 on 1/31/2014

Make sure you have a good amp cause this sub has lots of power.

Pros: Power, infinity quality

Cons: Price a little steep for 1 but way better than competition

Good Strong Punch

JGrant from Atlanta, GA on 11/20/2013

Crutchfield Customer Review (What's this?)

This speaker is perfect for those unsure of how you want to power your subs and still gives the flexibility to change later with the 2/4 ohm selector switch. I wired two of these subs to a 1200w mono Kicker amp and was pretty impressed with the end result. Bass is accurate and provides plenty of punch wired at 300w per sub.

Pros: Great looks, good construction, ohm selector switch.

Cons: Fairly expensive, somewhat deep mounting depth.

free air

adam from rochester, Mn on 10/21/2013

I was looking for a free air sub to replace the factory sub in my 2005 deville. This is a great sub, im running a line out converter to my amp so it doesnt sound as good as if it were coming from rca's on a deck but that'll come here soon enough. Infintiy recommends 175 watts in free air applications but it can handle more. Im running it at 2ohms 250 watts rms.

Pros: Build quality, selectable ohms, performance, can be used free air or in a box.

Cons: None, its a high quality sub.

great quality

jeeves from vegas on 9/27/2013

have lots of experience in the car audio industry and decided to get these after doing research on what i felt would be best for my setup. My last system had 2 L7 12s but this time i was looking to conserve a little more trunk space and was looking for more quality. put this in the recommended .75 sealed enclosure powered by a polk 5 channel amp and have been impressed so far. doesn't hit the lows like my last setup but for the size this really packs a punch. One of the most accurate sounding subs ive heard...............been looking to hear reviews of it in a ported box with just one sub and couldnt find anything so i ended up buying one. while the sealed enclosure is slightly more punchy( especially if listening to rock music that has double bass) i have to admit ill be keeping it in the ported box. produces what seems to be a wider range of frequencies and is still very accurate, also doesn't require my gain knob to be as high as it was in the sealed enclosure. i listen to all genres of music and feel ported was the way to go if you don't mind losing a little more trunk space

Pros: originally was nervous about the gold but it looks very nice in person, great sound reproduction, easily switchable impedance.

Cons: recomended ported box size is kind of big. Makes me wonder how the 12 inch version compares.

Best low powered sub I've herd

Joe from Michigan on 3/7/2013

Best low watt sub you will ever hear. Very very accurate and clean.

Pros: Sound quility

Cons: None

Infinity 100.9w

anudra01 from FL on 4/11/2012

I have an Infiniti G37 and I installed two of these badboys and it's the best. They are powered by an infinity kappa one and the bass hits really hard. I would recommend this sub to anyone.




huller from il. on 3/4/2012

Crutchfield Customer Review (What's this?)

great speaker, has the infinity sound i was looking for . my last sub was about 11 years old and finally broke the voice coil wirers. that was also an infinity. so im glade i went with another great speaker. and getting it from crutchfield makes life easy. thanks! recomend this 10' sub to any good box. p.s has a cool factor look!!!



Infinity 100.9w Kappa

MikeG from South Jersey on 12/15/2011

This subwoofer not only looks awesome but also sounds amazing. I have this thing in a sealed box under the back seat of my truck and man does it hit hard! As an avid listener of dubstep, electronic music and some hiphop, low end sounds are very important to me and the kappa woofer delivers. This is also a great sub to show off to your friends since the woven glass fibers look pretty cool and assure you that your cone will not be susceptible to breaking over time. Get the Infinity Kappa subwoofer, you will not be displeased.



infinity sub-par

agentorange from casper,wyoming on 10/1/2011

Crutchfield Customer Review (What's this?)

well after reading all the reviews on this sub i thought what the heck? it sounds like a good buy. apparently i was wrong. I bought a sound ordnance box, sealed from crutchfield with the recommended air space and ran a rockford fosgate punch 300.2 amp to it bridged at 2 ohms, im not exatcly sure what the proper way to wire it is but the reviews said you can't wire it wrong. so it sounds alright with low pass but when you crank up the volume it makes a popping sound that i can not decipher. i am sure im only running 300 watts into it but it says its rated for 350 rms so im not sure whats going on....btw it sounded good in my wrx but when i put it in my jeep grand cherokee it sounded weak and made the popping noise.




Dave (03 Mustang) from WI on 3/27/2011

Crutchfield Customer Review (What's this?)

Well, I have 2 of these installed in a custom box powered by Kenwood 1200m. They sound great, they are very accurate and hit hard. You will not be disappointed! Great buy for the money, worth every penny.



A subwoofer with a little glam!

Rob from Takoma Park, MD on 3/14/2011

Crutchfield Customer Review (What's this?)

If you are in the market to purchase a component subwoofer, look/spend no more. This little gem rocks! I have mine installed in a sealed box, paired with some Infinity Reference 6030cs' (installed in the front doors). Needless to say, I am quite pleased with the results. Oh yeah, the woofer... Get it! As someone else pointed out, you will NOT be disappointed. Just be sure, though, that it is powered by a mono amp; I have the Polk Audio - Monoblock PA880 which I purchased at Best Buy (Crutchfield does not sell it). And you should also run your door speakers by a separate 2- or 4-channel amplifier. Though two (2) amps total, the signals are segregated to where your music is much more cleaner and professional-sounding.



Beautiful Sound

Enrique from Bronx, NY on 2/8/2011

Crutchfield Customer Review (What's this?)

It's a beautiful Sub that gets a lot of attention. Importantly, this sub sounds very clear and crisp not boomy like others. However, do not be fooled this sub has a serious punch factor. I listen to hard rock, jazz, latin jazz and hip hop to R/B. All music sound just awesome, don't think about it, just buy it you wont disappointed.



In Custom enclosure in 300zx With Kappa 5 Amp

Alexander1225 from Florida on 1/11/2011

This sub is a sound quality sub, which can be seen by the price and specs. The sub sounds great and has plenty of volume in my small car. Overall i wish it was a little louder, but i would never give up the sound quality this guy provides, it is amazing. I would recommend this to a friend who isn't on a tight budget for a car audio system.



Extremely pleased

Cmac06 from Alabaster, AL on 1/23/2010

Crutchfield Customer Review (What's this?)

I was looking for a sub that would fit in a sealed enclosure. Specifically, I was planning on putting a system together using the QLogic enclosures for Sub and Kick panels. This sub was a good fit because the sub sealed enclosure specs state the it needs .75 cubic feet of space, and the QLogic box for my vehicle was about the right size within 15%. I actually spoke with a sales consultant about this, and he assured me that the specs were good for both items. To test the setup, I hooked the sub up without any crossover, and I must say that this sub is extremely musical. It played well above the stated frequency range of 25-400Hz, but when tuned in to do its job, it was absolutely phenomenal. The bass in the setup is extremely punchy and accurate. Bass guitars sound absolutely incredible, as well as the lower octaves on a piano. The only issue that I could see is the the resistance switch moves quite easily, so care must be taken when mounting the sub in an enclosure. Otherwise, I am very pleased with the purchase.



Infinity 100.9w

Michael from NJ on 1/5/2010

Crutchfield Customer Review (What's this?)

This sub hits hard and clean. I was limited in box size and could only get 0.65 cu ft out of my box. I put some polyfill in it from day one and it hits HARD. The clarity is also amazing. Very tight. The construction is top notch and the cage is solid. I am powering it with a Polk 1100.5. The amp is rated at 400w RMS at 2 ohms, which is the setting I am running the sub on. Highly recommend.




Anonymous from Northern California on 10/13/2009

Anyway everything I have in my truck is from crutchfield which includes an Alpine cda-105, alpine power pack, Infinity components, Infinity coaxials and infinity 600watts at 2ohm amp. I just put this sub in my Ford Ranger today in a small .85 box and wow does it hit. I dont even have it broken in yet but I'm pleased already. So far I've thrown Beastie Boys at it along with some CCR, Third eye Blind, Ben Harper and boy does it hit it all. Its very precise and clear. I can tell why Crutchfield added it to its Signature series. This is defiantly a well built product.




Hands-on research

Product Research

Enclosure Compatibility


Selectable Impedance: For increased system flexibility, the woofer impedance is switchable. There is a 2 ohm/4ohm switch above the wire terminals, this provides easy configuration of the voice coil. The power handling is the same for either setting; 350 watts RMS/1400 watts peak.

Woven Glass-Fiber Cone: The cone material is extremely stiff, minimizing cone flex; this results in very low distortion and improved clarity.

Vented Polepiece: Venting the polepiece reduces air compression under the dustcap which minimizes mechanical noise and provides more constant mechanical Q for reduced distortion.

Terminal: The set screw wire terminals will accept bare wire up to 8 gauge.

Enclosure Compatibility

Sealed Box: Infinity recommends a sealed enclosure with an internal volume of 0.75 cu/ft.

Ported Box: Infinity recommends a ported enclosure with an internal volume of 1.5 cu/ft with one 3" diameter x 10.25" long port. This equates to a tuning frequency of 30 Hz. They also recommend using a sub-sonic filter.

Sealed Bandpass Box: When using a bandpass enclosure Infinity recommends a sealed rear chamber volume of 0.75 cu/ft and a ported front chamber volume of 0.75 cu/ft with a 4" diameter x 7.5" long port. This equates to a tuning frequency of 60 Hz. They also recommend using a sub-sonic filter.

Free-air Mounting: In addition to being compatible with sealed, ported, and bandpass enclosures, the woofer can be used in free-air applications. A free-air subwoofer is designed to be mounted on a baffle board, which separates the front of the speaker from the back. For instance, you could mount this woofer to a board attached to the rear deck or placed in the trunk against the rear seat. The trunk acts as the enclosure housing the subwoofer. Because there is no specific volume of air to stiffen the suspension, the free-air power handling is approximately half that of the woofer in a box, in this case 175 watts RMS.


Thiele-Small Parameters: Because the woofer has two impedance settings, there are two sets of Thiele-Small parameters:

DC Resistance (Ω) 2.0 4.2
Inductance (mH) 1.17 1.17
Vas (liters) 18.05 18.05
Qms 4.18 2.43
Qes 0.51 .53
Qts 0.46 .44
Fs (Hz) 33.8 33.8
Radiating Area (m²) 0.033 0.033
Xmax (mm) 17.5 17.5
Motor Force Factor (TM) 12.47 17.72

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.

Q & A

Customer Q&A

Crutchfield asked  
Why did you buy this?

Specs will work with my Sealed Enclosure. Its a Harman. To match my JBL speakers in my Tucson. [ Chris  May 31, 2016 ]

5 questions already asked

Thanks for your question. For information on selecting the best sub for your 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 sub models and help you make the best choice for your system. [ Kenny  Jul 06, 2016 ]  Staff

3 answers This is the amp that i have. How would i go about wiring 2 infinity kappa 100.9w subwoofers at 2ohms? 4ohms? [ Jaime  Jan 13, 2016 ]

There are several different ways you can wire the subs given they are 2 ohm / 4 ohm capable. Your best bet is to call Crutchfield customer service and give them the model of your subs and amp so they can help you with the best (most efficient) way to wire them. [ Eric  Jan 13, 2016 ]
You really need to see diagram for wiring. It's too difficult to describe with just words. But there are a few ways you could go about it. I think matching the ohms to the amp will give you the easiest "series" wiring. Just do a search for "subwoofer wiring diagram". You'll find alot of good diy guides. One more thing to try...Crutchfield online chat, during my installation of my single sub and amp, I ran into a bump. I went to the online chat and the customer service rep was able to send me a great pdf thay was specific for my car to assist in my intallation. Good luck! Great speaker btw. My single 10 is clean and deep. [ Omar  Jan 13, 2016 ]
If you purchased the product from Crutchfield, feel free to contact our Tech Support team. They can walk you through the settings 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: [ Krissy  Jan 13, 2016 ]  Staff
My box and grill was custom built [ RICK  Sep 04, 2015 ]
Thanks for your question. For information on selecting the best sub 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. [ Krissy  Feb 04, 2014 ]  Staff
Sorry don't know not that involved but have plenty of quality sound. [ ANDREW D  Jan 28, 2014 ]