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Alpine KTP-445U 4-channel Power Pack Amplifier

4.6 out of 5 stars 239 customer reviews
| 87 answered questions

Price: $113.90 & FREE Shipping. Details

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  • Compact Class D amplifier for factory and aftermarket receivers
  • Universal plug lets you send signal from RCA outputs or speaker-level wiring
  • Runs off same power circuit as receiver.
  • 45 watts RMS x 4 at 4 ohms (CEA-2006 compliant)
  • Dimensions: 7-7/8"W x 1-1/2"H x 2-9/16"D
19 new from $98.00 3 used from $92.00
$113.90 & FREE Shipping. Details In Stock. Sold by PriceGrab and Fulfilled by Amazon.

Frequently Bought Together

  • Alpine KTP-445U 4-channel Power Pack Amplifier
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Total price: $118.69
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Product Features

  • Size (LWH): 9.25 inches, 7.5 inches, 3.25 inches
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Product Description

Universal Class D 4-Channel Head Unit Power Pack for Use with all Aftermarket & Factory Receivers

Product Information

Product Dimensions 9.2 x 7.5 x 3.2 inches
Item Weight 2.4 pounds
Shipping Weight 2.4 pounds (View shipping rates and policies)
Domestic Shipping This item is also available for shipping to select countries outside the U.S.
International Shipping This item is not eligible for international shipping. Learn More
Item model number KTP-445
Customer Reviews
4.6 out of 5 stars 239 customer reviews

4.6 out of 5 stars
Best Sellers Rank #8 in Electronics > Car Electronics > Car Audio > Amplifiers > Multichannel Amplifiers
Discontinued by manufacturer Yes

Warranty & Support

Product Warranty: For warranty information about this product, please click here


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Customer Questions & Answers

Customer Reviews

Top Customer Reviews

I installed two of these this past weekend. Both in new Jeep Wranglers. When I pulled it out of the packaging I was confused. I'll give you some pointers on installing this.

First of all you will need 4xRCA outs coming from your head unit. Most (if not all) decent aftermarket stereos include these. There may be two more for the subwoofer.

There are two sides to the unit: the harness that plugs into the left is for your speakers, remote turn on lead, and power. All you have to do here is match up each wire with what comes off the wiring harness you bought for your stereo. Use solder to connect wires.

The harness that plugs into the right side is where the RCAs coming off the head unit plug in to. The RCA harnesses that come with the amplifier are labeled F/R, just make sure you match them up with the RCAs you have running off your head unit to the Alpine harnesses. When you have them connected you should test L/R and F/R on the head unit to make sure they are matched up properly.

You have to buy 2 sets of RCA cables as the amp does not come with them. After you buy your new RCA cables, run them from the back of your head unit, into the RCA adapter harness, then plug that into the right side of the Alpine amp.

That's it.

8 month update: Still works great and runs cool. It is still in my glove box without issue.

Almost 2016 update: Still works great!
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So let's start with what this is NOT.

It is NOT a "big power" amp that is going to rattle your windows and piss off the neighbors. Nope. It's a small, Class "D" amp that roughly doubles to triples the power output of your existing head unit. To really take advantage of it you need RCA outputs from the head, although it will work with speaker-level outputs. This means that with a FACTORY head unit you will get much less than this amp can offer.

Let me explain -- an amplifier can only amplify what you feed it! If you feed it trash you get louder trash. Your head unit's amp is only so-so to start with (yes, even the expensive aftermarket ones because they figure if you care you'll use the preamp outputs instead!) so you're inherently limited. As a result if you want good sound quality you need RCA (pre-amp) outputs from whatever you're going to connect this to, and you also need to use decent-quality cables (don't waste your money on things like "monster" cables, but do get ones with 100% foil+braid shielding - you can tell they're reasonable in quality because they've got some thickness to them.)

Now let's talk about the amp itself. It's a Class "D" amp. A Class "D" amp is EXTREMELY efficient because the transistors in it are either "on" or "off." They thus dissipate very little power as heat. That's good. However, the way they work is by switching the power at extremely high speeds (typically at least 10x the maximum 20khz audible sound frequency) and then using a low-pass filter made up of reactive components to smooth the output. Due to the way these amplifiers work energy is reflected back up into the power supply as a natural part of their operation.
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The Alpine KTP-445U is a great amp hands down!! It was easy to install, I have experience installing amps so it was probably easier for me than if you have never done an amp before. First thing I love is you don't need an amp installation kit as this unit uses the factory or after market power wires which saves time and money on the installation. Your options for mounting are increased because of it's compact size. This amp sounds great... replaced a stock factory amp that had failed and the quality was even better than what the car had come with and it saved him $800 over what the dealer wanted to put an inferior stock amp back in the car.
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Let me first say that I currently own a car that has a aftermarket system in it that consist of one 12" JL subs running off a alpine monoblock pdx amp @ 2ohms/800 watt RMS, components up front and 6x9's in the rear running off a 4 channel 550 watt pdx alpine amp and it rocks hard. So with that said I know car audio and have been building out system for over 20years. Well I bought a 2014 ram 1500 Quad cab 5.7 HEMI 4x4 big horn edition with the 8.4 radio with the stock speakers. Wasn't a bad stereo system for the average person to listen to, but like most factory stereos it lack quality sound due to poor speakers and a crappy head unit(radio/deck). Well like most new vehicles, the 8.4 radio in this truck is tied to several features like the heating and cooling controls, navigation, backup camera, sat readio, settings for the truck, and several other feature as well. So replacing the head unit is not really an option I'd like to explore with this new truck. So I started to look around for a small foot print amp that didn't require running a power line with inline fuse from the battery to the amp and that could be placed somewhere behind the dash. I came across a few brands like clarion, fosgate, some off name brands, and this alpine unit, KTP-445U. Already having alpine amps in my other car, I knew I couldn't go wrong with it, so I made the purchase. Along with the amp I figured I'd order speakers to go with it. I decided on the Kicker-41KSC354 3 1/2 for the dash, Kicker-40CS654 6.5in for the front doors, and the Kicker-41KSC694 6x9's for the rear doors. The installation of the amp was simple and straight forward.Read more ›
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