Infinity Kappa Five

5-channel amplifier — 50 watts RMS x 4 at 4 ohms + 300 watts x 1 at 2 ohms

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  • Infinity Kappa Five


  • Infinity Kappa Five


  • Infinity Kappa Five

  • Infinity Kappa Five

  • Infinity Kappa Five


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Our take on the Infinity Kappa Five

by Gabrielle Thorndyke

My system has plenty of power. Who needs an amp?

You might think you don't need an amp because you have a 400-watt system in your car, or because your new stereo puts out 50 watts a channel. But those are peak wattage ratings, which may boil down to 15 or 20 watts per channel, using the more realistic RMS rating. An amp sends your speakers the power they need to deliver your music with clarity and impact, whether you're using factory speakers or high-performance components. And low-frequency reproduction requires lots of power, so an amp is an absolute must if you're adding a sub to your system.

Infinity designed the latest Kappa Series amplifiers to deliver increased efficiency and performance from an extremely compact package. These slim powerhouses stand only 1-3⁄4" tall, so they'll fit easily in spaces where other amps just won't go. And efficient heat dissipation means these amps won't get too hot in tight quarters.

The Kappa Five 5-channel amplifier makes an ideal match for your high-performance Kappa speakers and subwoofer, dispensing 50 watts of clean power per channel to four full-range speakers, plus up to 300 watts to a subwoofer. A built-in crossover and input selector switch lets you configure your setup for the best possible performance, while the amp's Dynamic Bass Optimization circuit shapes the bass to get the best possible performance from your sub and enclosure.

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The amp's Class-D design generates less heat, eliminating the need for large heatsinks. Non-stop Thermal Protection circuitry adjusts the amp's output so it runs cool no matter how hard you push your system. Balanced speaker-and preamp-level inputs reject engine whine and other noise from your car's electrical system. A unique detachable power/ground plug lets you connect and disconnect large-gauge power cables in one easy step.


  • 5-channel amplifier
  • 50 watts RMS x 4 + 200 watts RMS x 1 at 4 ohms
  • 75 watts RMS x 4 + 300 watts RMS x 1 at 2 ohms
  • 150 watts RMS x 2 bridged + 200 watts RMS x 1 at 4 ohms
  • CEA-2006 compliant
  • variable high- and low-pass filters (32-320 Hz, 12dB per octave)
  • bass boost: 0-12 dB
  • frequency response: 10-75000 Hz (front and rear); 15-320 Hz (subwoofer)
  • Non-stop Thermal Protection ciruitry
  • Class-D amplifier design
  • differential balanced speaker-and preamp-level inputs
  • 4-gauge power and ground leads and a 80-amp fuse recommended — wiring and hardware not included with amplifier
  • fuse rating: 40A x 2
  • 7-1/16"W x 1-3/4"H x 14-3/16"D
  • warranty: 3 years
  • Our 60-day money-back guarantee

Hands-on research from the Crutchfield Labs (what are the Labs?)

Features and Specs
RMS Power Output (Watts x Channels) 50 x 4
200 x 1
Peak Power Output (Watts x Channels) N/A
Power at 2 Ohms (Watts x Channels) 75 x 4
Bridged Power (Watts x Channels) 150 x 2
Minimum Impedance Bridged 4
Minimum Impedance Unbridged 2
Best Frequency Response 10-75k Hz
THD at Rated RMS Power 1%
Signal to Noise Ratio 85 dB
Input Voltage 14.4v
Amplifier Class D
Low-Pass Crossover Frequency 32-320 Hz
Low-Pass Slope (dB/octave) 12 dB/oct
High-Pass Crossover Frequency 32-320 Hz
High-Pass Slope (dB/octave) 12 dB/oct
Bass Boost 0-12 dB
Bass Boost Frequency 10-80 Hz, Variable
Fan Cooled No
Fuse Rating 80
Speaker Level Inputs RCA (adapter req)
Preamp Outputs No
Width (inches) 7-1/16
Height (inches) 1-3/4
Depth (inches) 14-3/16
Parts Warranty 3 Years
Labor Warranty 3 Years
Product Research
What's in the box?

Download owner's manual

  • 5-Channel amplifier
  • Two 40A ATO fuses
  • 4-Gauge terminal adapter (installed)
  • Instructions (English/ German/ French/ Spanish/ Dutch/ Italian/ Swedish/ Danish/ Finnish/ Polish/ Portuguese/ Russian)
  • Warranty/Product Registration card

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 open the box, verify contents, 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.



Class D/DirectFET Technology: The Infinity Kappa Five features high-power Class D circuit topology with DirectFET transistors, a design that increases power output and overall efficiency, with improved heat transfer from the transistors to the chassis.

CEA-2006 Compliance: The specifications given by Infinity for the Kappa Five comply with the CEA-2006 Amplifier Power Standard from the CEA (Consumer Electronics Association). All manufacturers who comply with the standard can display the CEA-2006 logo on their product.

5-Channel Design: This amplifier is designed to power four full-range speakers and a subwoofer simultaneously. All five channels are 2Ω stable; at 2Ω the power output is 75 watts RMS x 4 to the full range channels plus 300 watts RMS to the subwoofer channel. CEA-2006 compliance is maintained at 2Ω, with less than 1% THD+N. The amplifier's front and rear channels are individually bridgeable, so the Kappa Five can run 5, 4, or 3 channels. When bridged, the front and/or rear channel output is 150 watts RMS into 4Ω.

Protection Circuitry: The amp features protection circuits and will shut itself down in the following cases:

  • DC Output: DC voltage is detected on the amplifier output
  • Over/Under Voltage: Voltage at the +12V (Battery) terminal is too high or too low
  • Short Circuit: Short circuit in speaker or speaker wire

Non-Stop Thermal Protection: Kappa amps protect themselves against excess heat with circuits that cool the amplifier down by gradually reducing output, instead of shutting down completely.

Status LEDs: Three LEDs on top of the chassis indicate the status of the amplifier. Two Power LEDs indicate the amplifier is on. The Protection LED indicates one of the protection circuits has engaged.


Rear Input Signal Select: set to 2 CH or 4 CH, based on how many line outputs from the head unit are feeding the front and rear channels

Subwoofer Input: 1 pair of RCA inputs

Input Select Switch: set to INT or EXT, based on whether the head unit has a discrete subwoofer line output

Input Level: 3 rotary controls match the level of the preamp input signals for front, rear, and sub channels; 200mV to 6V

Crossovers: The Kappa Five has 12 dB per octave crossovers on all the outputs. Each is continuously variable from 32-320 Hz. The crossover on the sub output is low-pass only. The crossovers on the front and rear outputs are independently set to low-pass, high-pass, or full range.

  • Frequency: 3 rotary controls set the crossover points for the front, rear, and sub channels; continuously variable from 32-320 Hz
  • Crossover Switches: 2 switches set the front and rear crossovers to low-pass, high-pass, or full range (the sub channel crossover is always low-pass)

Dynamic Bass Optimization (DBO): The Dynamic Bass Optimizer (DBO) is used to enhance low frequency reproduction in your vehicle. Conventional bass-boost circuits only increase bass at a fixed frequency, and cause the amp to consume considerable power. The DBO allows you to adjust the frequency, as well as the boost level (up to 12dB), allowing you to fine-tune the bass in your system to optimize performance. The frequency control also acts as a subsonic filter.

  • HP Freq: Rotary control to set the sub-sonic filter and boost frequency; 10-80 Hz
  • Boost: Rotary control to set the boost level; 0-12 dB


Power: A 4-Gauge terminal adapter is installed on the power/ground/remote terminals; if removed, it reveals three 8 gauge set screw terminals (Infinity recommends 4 gauge power and ground when the power cable is more than 4 feet).

  • +12V: Set screw terminal for power wire from battery; handles up to 4 gauge wire
  • Remote: Set screw terminal for remote turn-on lead; handles up to 12 gauge wire
  • Ground: Set screw terminal for ground; handles up to 4 gauge wire

Front and Rear Channel Inputs: 2 pair of RCA inputs.The amp will accept a speaker level signal through the RCA inputs. A speaker wire to RCA adapter is needed (136XDCLR2S, sold separately).

Speaker Output: 10 Set screw terminals (5 pair) for connecting speaker wires; handles up to 8 gauge; front left, front right, rear left, rear right, and sub.

Fuses: 2 Slots for 40A fuses (installed)

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Infinity Kappa Five Reviews

Average Customer Review:

11 people say:

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5 out of 5

Infinity Kappa Five Channel Amp

Written By Leggo, Newton, Ma. on Thursday, September 27, 2012
I don't know much about this stuff. I paid a pro to put a stereo in my truck that would make me happy. JDK sound and Security, recommended this amp with a Kicker 10" sub and Infinity Kappa speakers. I am very happy with it after about six months now. Really hits hard and clean!
Looks and sounds good and fits anywhere. Powerful!
1 out of 1 people found this helpful
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3 out of 5


Written By Spidy, Minnesota on Saturday, April 21, 2012
I got this amplifier a year or so ago. I've had it in a variety of applications. At first, I liked it very much, but I could always tell that the sound wasn't quite there. I figured that the distortion must have been coming from my other components. Well, I've replaced everything besides this amp--CDA-117 head unit, K2 Power speakers--and the sound is still not there. This unit is a very compact amplifier. I hadn't realized this when I bought it. The design goal for this is more than likely compact size, and not SQ. I just can't get it to sound good. This is a class-D amplifier--which is typically regarded as having much more distortion than AB or other designs. Class-D amplifiers are usually used for subwoofers because of this. Class-D amplifiers can sound very detailed and clear when designed properly. I was hoping this would be one of the well-designed class-D amplifiers. The class-D in this case was optimized for temperature regulation in tight spaces, and not SQ like I had hoped. The treble is often harsh to my ears--except during times with a relatively clear sound-stage, like a vocal solo. Mid-range is somewhat hallow, but this may just be because the treble can be so over-powering. Bass is punching, but not tight. When the sound-stage is full, this amplifier offers little separation--it sounds like everything is coming out of two speakers, and not pleasant to listen to. Overall, this amp could be good if you have no space, but not any good for serious listening.
Good for small spaces, looks cool, comes with nice terminal adapter for lower gauge wire.
Sound quality just isn't there, sibilance exaggeration, poor headroom on subwoofer channel (I have to have the subwoofer gain up all the way on the amp and all the way on my head unit with 4v outputs, and have the speaker gain turned to less than I'd like so that the subs can keep up) , questionable electronic filtering
2 out of 5 people found this helpful
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5 out of 5


Written By Fran, Pittsburgh on Monday, August 15, 2011
This Amp is powerful in my Aveo. I have it teamed up with the Kappa 63 and 42 series with the 120.9W sub. Can I say Yeeaaa Booooyyyyy!!!!!!!
4 out of 4 people found this helpful
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3 out of 5

Good AMP....had/solved Odd Issue other reviewer had

Written By AnthonyD, Michigan, USA on Tuesday, May 03, 2011
I purchased this amp with high hopes. At first I was happy for about 1 week. After that, it went haywire. It kept forcing all the power to the front left speaker and the other 3 were getting fuzz. The problem was odd, but managable. You know how you can tell when your engine is warmed up when the temperature gauge is in the middle.........well, don't turn on your stereo until your car is warmed up, then it works perfectly fine with no issues 100% of the time. If I turn it on before the car is warmed up (no matter the outdoor temperature) it does not work properly and force power to one speaker. Other than that, it powers my 12" sub and 4 speakers with no problem. My other components were professionally inspected and also everything was professionally installed, they said it must be the amp.
4 out of 8 people found this helpful
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5 out of 5

Infinity Kappa Five

Written By yo, philadelphia, PA on Tuesday, April 12, 2011
This amp sounds awesome, definitely "loud enough". Sounds just as good as my old set up which was a JL 300/4 and JL 1000/1 with all JL speakers. Obviously the bass isn't as loud/ vomit educing, but it still is enough to be exciting. This thing is balanced with it's self so it sounds really balanced. I'm pushing infinity reference 6.5 components, infinity reference 4x6 coax, and a JL 8W7 in a sealed box. I do need to have the sub gain a lot higher than the speaker gains to get a balanced, bass heavy, sound. I'm guessing it's because the speakers are 2ohm and the sub is 3ohm. Or the fact that I'm using a small sub. Either way this amp is awesome and you will be impressed.
5 out of 5 people found this helpful
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5 out of 5

2 Kappa 60.9CS and a Kappa 100.9w Powered in my 300zx

Written By Lex1225, Florida on Saturday, January 01, 2011
This amp was replacing the alpine power pack, and did it ever make a difference. It is very tune-able with all passes and filters right at your screw drive tip. Amp is very small and puts out a big punch. This amp powered all my components very clean and crisply, and if you consider that my components can do 30 more rms and my sub another 50rms, this is great. No fear about blowing anything, not to mention it matches everything nicely. Overall i would recommend this to anyone who wants a SQ amp not a loudness one. If you want loud just go with kicker, its cheaper and louder while being bad on SQ.
7 out of 8 people found this helpful
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3 out of 5

Kappa 5

Written By joe, Milwaukee, WI on Wednesday, May 26, 2010
If i could only review the sound quality of this amp i would give it a 6 out of 5. When it worked, the highs and mids were dead on and crystal clear. Same for the bass. (the high and low pass filters really help). The only reason i am giving it a three is because the bass has periodically been cutting out. My sub is fully broken in, i have a 3 farad capacitor, 4 gauge wire, and i double checked all my connections and voltage readings, so i know it's the amp. Everything worked perfectly for the first 4 months. Then the bass started to cut out. And it isn't just when i crank the volume, it happens at very low volumes too, and the bass can stay cut out for periods of time as long as 15- 20 minutes. I do realize that this amp isn't cooled internally, and the temperatures in my area have gone up a lot this past month, so it could be the amp overheating- but i can't tell for sure. Overall, this amp sounds great, but for the price, it should last a lot longer than 4 months.
7 out of 7 people found this helpful
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5 out of 5

Works great!!!

Written By Carlos, Maspeth, NY on Monday, February 15, 2010
Im starting in this new world of sounds!!! great performance, easy to set, you can fit it almost anywhere. No complains at all.
5 out of 5 people found this helpful
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1 out of 5

Good Luck

Written By Chris, Thomasville, NC on Monday, January 18, 2010
Crutchfield Customer Review (What's this?)
Ive been a fan of infinity since I installed my first stereo system. Past experiences were with good qaulity products and no problems. I just finished installing all Kappa components in my 2010 Civic. I was extremely happy for the first 2 weeks. Great sound qaulity. 3 weeks after though, i had a tweeter go out and had to replace it. the 5th week the amp went nuts and blew all my front components. Both tweeters and both woofers. the volume was around 6 on my HU but it sounded like it tried to send all the signals to the front channels at full power. I heard a buzz and then a loud pop. Was not satisfied with the overall qaulity of any of the Infinity equipment. Its JL Audio from now on.
9 out of 17 people found this helpful
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5 out of 5

Great sound in a small package

Written By Adam, Fresno, CA on Tuesday, December 01, 2009
I had been looking around for an amp that would fit under the passenger seat, as
the interior of my car is somewhat short on space. I wanted to be able to run
my component speakers and a sub, so I was mainly looking at 5 channel amps.
This was the only amp I could find that would fit under the seat with no
modification to the car. After hooking it up, I was blown away with the clean
sound and high volume I was able to create. Great quality, tiny package. Worth
every penny.
5 out of 6 people found this helpful
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5 out of 5

High quality amplifier!

Written By myriad1973, Toledo, OH on Tuesday, March 24, 2009
This is the first car amp I've purchased in 17 years. This was a very good choice. It has a very clean signal and it runs cool even when cranked at 2 ohms. The variable bass boost + infrasonic filter is a very nice feature to have instead of a fixed frequency. I am very pleased with this product. It is an excellent buy. If you have the extra money to spend, it is well worth it.
37 out of 38 people found this helpful
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1 question already asked

Why is there a high pitched noise that comes from the subs when they aren't receiving a signal to hit? [ AwsedreswA  Apr 27, 2014 ]
1 answer
  • 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: http://community.crutchfield.com. Or try our online support center: http://crutchfield.custhelp.com/app/answers/list/kw/. [ Krissy Staff  Apr 27, 2014 ]

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