I used a pair of the Infinity Kappa 120.9W's in a home, high-end audio system. I put them in 3 Cu. Ft. sealed boxes and placed one in each corner of the audio room. The Apogee Divas are closer to the listening chair, so the sub-woofers are behind them. The bass is awesome. I have heard many high-end subs and these are as good or better than some of the expensive high-end subs. With a db or two of boost at the low end, these subs go down nicely to 20 Hz.

I originally had an Infinity 1262w reference sub and the voice coil separated one day. Rather than trying to get a refund or warranty work I decided to get an upgrade and go with the Kappa. I now wish I had gone with the Kappa in the beginning! The sound is amazing. My box is sealed for clean tight bass and this sub delivers. I don't care for people to hear me coming a mile away but this sub is incredibly loud inside my car. To the point that people who listen to it generally have to plug their ears.

I am only putting about 300w into it but it can shake my entire car and still play cleanly without any boominess or muddy distorted sound. I don't always listen to music like rap or hip-hop, so when listening to classical music or country the bass is supremely clear and not overpowering. I couldn't ask for a better sub for the money!

I installed this sub in a BMW X5 to supplement the bass on the Hi-Fi system. Wow. This sub provides deep, clean and rich bass. Way more that my ears can stand. Bonus, it looks great.

In a Sonic Sub Box: 1H12-1.0 (Gray) with dynamat on the inside to get closer to the 1.0 cubic feet spec. Drilled through the connector plate and ran monster cable 10-gauage speaker wire straight from the amp to sub.

Powered by Infinity Kappa Five (300-600W on the mono sub channel),
running 4 gauge and the BOSS cap-20.

Can make 2002 Monte Carlo SS rearview mirror fall off. I think I had it set at 320LP with the db gain set somewhere between 60 and 80hz (I think). A 160LP might be what its on now, I was having a problem with my amp cuttin out, so I reduced the high frequencies from the deck too and the system can run at max volume now. The 400hz max range was kinda much to believe anyway (from speaker or amp@320).

Once I get the candy amp rack made I think I'll pick up Infinity's other sub amp and give this thing the power it wants.

Great deal for the price, lets you get the extended warranty option. Decent look and VERY durable, but won't look pretty after it shows you it is durable (the shimmer wears off).

Had 2 in 2 sealed 1.2cf boxes they sounded good about 4 months and they tore all the way around. The fiberglass cone has a rough edge where it is glued to the rubber surround and cut the rubber. I tried to glue them but never sounded right. It's too bad they just didn't smooth the edge of the cone before gluing. I exchanged them for power caustic mofo that don't sound as good but much stronger. Do not use stated power cut in 1/2 for vented box keep ur warranty and packaging.

I'm 44 years old and this is my first sub...

This being said, I have always been a music enthusiast, and I'm very hard to please, I need a good sound quality system, and this sub was exactly what I was looking for!

I changed everything in my car, radio, front and back speakers, and put a nice amplifier to go with it, the only thing missing was bass...

After going over mountains or reviews, I finally decided to go with Infinity, I bought one of these, that I put in a sealed box, WOW this sub makes my car shake to the core!

Incredible bass in my car, but only in the car, I did not want the bass to overwhelm my vocal, and this sub blends perfectly with the front stage,
I threw everything at it, Pop, Rock, Metal, Techno Bass, even Classical!
It reproduces every note to perfection, bass sound like bass, drums sounds like drums.

I tried the sub a both impedance's, first a 4Ω, then at 2Ω, my amplifier sends 300w at 4Ω and 500w at 2Ω, worked perfectly at 2Ω but was a little to much for my taste so I put it back at 4Ω.

all in all this is a very nice peace of technology, and the price is respectable compared to other SQ subs out there, and I highly recommend this product.

If you are a Hip Hop fan, one will not be enough for you, two 10" or two 12" will shed the rust from your car in no time flat...

I wanted to add some low frequencies to my X5 which did not seem to play below 100 hz. After a lot of research, I selected this sub and hooked it up to a JBL GTO3501 mono amplifier. Could not be happier. I wasn't looking for kick *ss bass but rather fill the cabin with low bass that I can feel. This setup rocks. It will kick if you want it too but what I like best is the flexibility it has to sound excellent with all kind of music. It took some time to properly tune the amp and well worth it.

I have this driven by a Pioneer GM-D7500M in a custom built cabinet. 4 Infinity Kappa 63.9i driven by a Pioneer GM-D9500F rounded out my system. The sound quality is truly amazing. I've had several audiophiles and musicians in my car and they want the me to do the same system for them.

I have owned this subwoofer for 4 months and I couldn't have been happier. I can't say anything negative about this subwoofer. There are many great thing about this subwoofer.

1. It works well in a compact box.

I have it in a 1.0cu ft sealed Sonic sub box stuffed with polyfill. Unlike many car subwoofers, this one is actually optimized to work in reasonably small sealed boxes (1 to 1.5 cu ft). WinISD recommends 1.2cu ft when running in 4ohm mode and 1.7 cu ft in 2 ohm mode. I run it in 2ohm mode, in effectively a 1.25cu ft box (due to polyfill), with resulting qtc of about 0.76, which is almost perfect.

2. Good sensitivity and power handling.

Don't worry if you have a modest amplifier. This subwoofer can still get very loud when running off a 250watt RMS power, much louder than is actually necessary IMO. However, should you want to play it a little too loud, I don't see why you could power it with 500w amplifier. Harman Kardon is being obviously modest with subs power rating. The xmax figure alone suggests that this Kappa should take up to around 500watts while still operating in its "SQ" range.

3. The cone looks great.

4. Low Inductance. Most subwoofers have such high inductance that their manufacturers do not even report it. This sub has Le of around 1.18mH which is considered much better than average. Low inductance is generally good for transient response and blending with the front stage.

4. Great sound.

Let's finally get to the core of the review. This subwoofer plays very cleanly and transparently. What I hear is a very clean, robust bass with a good texture. It's good for practically any music genre. Midbass output is higher and cleaner than that of an average car sub, which makes blending with the fronts much easier. Don't be afraid to bump your crossover frequency a little higher. (I have mine at 70Hz, up from 60Hz with previous sub). I could go on to continue building a list of things that this subwoofer does correctly, however, I think it would be much easier to say that it does nothing wrong IMO.

Based on what I have heard so far, most Harman Kardon (owner of JBL and Infinity) subwoofers are very good performers, and this subwoofer is a proof of it. I feel like I have been converted. Should I look for a higher end sub in future, once I become rich and famous, I will probably pick up a JBL WGTI from the same company.

I have 2 of these Kappas, each being driven with a JL Audio 500/1v2 high-damping amplifier. I have the impedance switch set to 4 ohms on each sub for better excursion control. Let me tell you this, these Kappas reproduce every range of bass like a pro... very detailed yet extremely hard hitting. I have them in a sealed, 1 cubic foot per-sub enclosure, and they handle every bit of the amps' power (gains set at two-thirds) using common sense with the volume control/ bass knob. If you want remarkably precise sound that can still rumble the car very well with enough power, these Kappa's will do the job for sure. The impedance switch is very nice. Make sure your enclosure cut-out diameter is large enough... the mounting diameter of these subs are 11 & 1/8 inches across. You can always sand out your box holes with 40-grit sandpaper to make them fit, but it's some work (and vacuuming dust). If you want superb sound, go with these in a sealed box, they would probably work fine in a ported setup also, but the average person with little experience with boxes who likes tight, accurate bass should be very happy with these Kappas in a sealed enclosure.

I have 2 of these remarkable subs in my Camaro. I have them set to 4 ohms, and I'm driving each sub with one JL Audio 500/1v2 amplifier... They handle the power very well, I have each JL amp set two-thirds of the way up. The sound quality is brilliant, and the bass is very deep sounding, even for the 1 cubic foot per side enclosure they are in. These sound just as good (and look way better) as the JL w3v3's- I've owned some before. The switchable impedance makes these subs very flexible... I'll probably own mine till I'm 40 yrs old! The only thing to pay attention to is their relatively large cut-out diameter... They won't fit into the same opening size as the Reference 12"s will (too big across)... So make sure your enclosure can accomodate these big boys. They are solid and weigh almost as much as Alpine Type R's, while being more effecient and clearer sounding. 5 stars on these!

I bought two of these subs six months ago and they have amazing sound quality! They are in a very small truck box underneath the back seat of a 2006 dodge ram. Total air space per sub is .65 cub inches. I was amazed at how low of a frequency they could reproduce in an enclosure that small! Throughout the whole frequency spectrum these subs are amazing no matter what kind of music you listen too. I am very pleased once again by the quality and design of Infinity. These subs are a great deal and you will enjoy the quality of their tonal reproduction from 28hz up!

i powered 2- kappa 12" on a kappa one amp. they sound really good and looks great. I guess there's a manufacturer defect - the coil from the frame to the cone cam off. very disappointed in the subs, but sonic is highly recommended. great service, tracking orders, ease of return.

This is a great sub with very good sound quality. I had two of these and the bass was good but not really loud if your a true bass head.

I love the look of this sub especially because it looks like the rest of my kappa speakers. The bass is nice and tight in a 1.0 cu ft box but it doesn't seem to like rolling bass to much. Then again that might just be my application but all in all it is a great sub.

A have been using for over 6 months. It is giving the response that I expected. Good high quality sound. I would definitely recommend this product to others.

i got two of these subs for Christmas and now since they are broken in I can really see why infinity is top notch. the bass is so clear and the variable impedance switch should be on every new subwoofer.

The kappa series is awesome looking. I have a 500 watt amp powering this baby in a custom enclosure in the trunk facing front through a pull down backseat. Lows sound great and bumps the car nicely with various music. The biggest reaction you get is from the looks of the thing. Other than that it's not rediculously loud so 1 of these won't rattle the neighborhood. Honestly though I don't see the need for another one.