Alpine KTP-445A Head Unit Power Pack

I did not want an amplifier. I did not want an amplifier. I did not want an amplifier. There. Now that that is out of the way...The KTP-445 comes in two versions. This review is for the "A" version (KTP-445A) which is wired for Alpine head units. It will work just fine with other brands or older Alpines, but you have to cut off the nice connectors and rewire them to fit your unit. For other brand head units (or Alpines made prior to 2005) you need to look at the KTP-445U (universal fit).I have this installed in my 2003 Jeep Wrangler and it is just enough to make my system usable with the top down while rolling at Interstate speeds. These seems to be a lot of confusion about this, so I will try to clear some of it up.This is not a 45x4W RMS amp! An aftermarket head normally has a small amount of amplification on board, and this simply boosts the TOTAL to 45W by adding to what it already there. On an Alpine this creates the full 45W per channel. It does this inline via a very long harness that is included in the box. The amp lives in-line between your aftermarket harness adapter and your head unit. You plug the amp's harness into the adapter harness. You plug the other end into the amp. Then you plug the other harness into the amp and clip that into your head unit's socket. No RCA plugs are used. Only the regular, main socket on the head is used by this amp. It is literally and truly a "plug and play" system.It supplies some surprisingly clean sounding power to your head unit. If you want more power but not some child-like, booty-smashing, "acoustic hair dryer" sound system in your car, this works well and is easy to set up.My system works very well together. Here is the basic setup so that you can see how this mini amp can fit in with other components, power-wise:• Alpine UTE-52BT Bluetooth Mechless Digital Receiver• Alpine KTP-445A Head Unit Power Pack• Alpine MRV-M250 Mono V-Power Digital Amp• Polk db521 5.25" Marine Coaxial Speakers• Polk db5251 5.25" Marine Component Woofers• Polk db5251 2" Marine Component Tweeters• Rockford Fosgate P3SD4-8 8" Shallow 4-Ohm DVC SubwooferThe Polk speakers work very well in an un-amped, stock system; they sound great, if a little bit bright. However, they can handle a small amount of amplification with no ill effects. This Alpine mini-amp does a great job of powering these speakers; you get some fairly solid power without distortion or noise. Paired with my Alpine mono amp to my subwoofer and my system sounds pretty darn good. Or at least *I* think so. ;-)I would strongly recommend this Alpine KTP-445A (or the U version, if applicable) for anyone who has moved beyond their stock head unit and speakers but who is not yet convinced that a sound system that can power a small town is what they really want in their car, or for those who successfully installed an Alpine head unit and who are ready for a bit more power without the wiring hassles of a regular, RCA level 4 channel amplifier. It is not too spendy, it is very easy to install, it works well and is well made. I am very pleased with mine.Notes specifically for Jeep TJ owners (Wrangler, 1997-2006) who are looking at this:This thing is great for a stealthy system. I can fit my MRV-M250 mono amp on the same bracket with this little guy and stuff them both up under the dash off the two bolts on the firewall for the tilt steering. (That seems to be the default place for amp mounting on a TJ if you want it hidden and off the floor. Do a Google image search for "Skinny Pedal Bracket" to see how to make one of these. You will have to figure out how to fit all that on the bracket, but once you have it figured out it *will* work.)Alpine has told me on the phone that both the amps listed above can safely be mounted inverted, so long as there is adequate air flow around them. The rep also suggested going to a hobby shop and buying a very thin, flexible sheet of Lexan/polycarbonate. (NOTE: not polystyrene, which melts and puts off some toxic fumes!) He said to fit that up above the amps to make a sort of umbrella to keep any rain off the amps. Yes, the Alpine rep owned a TJ, too. Nice!Alternatively, if you do not have a sub in your Jeep, or if you already have a sub amp under the dash and do not want to have to re-do all that work to fit the KTP-445A up in there with it, I have found that on TJs with the HVAC system using knobs (pretty much all of them) that this *can* be fit behind the HVAC control module, which is just below the head unit. I tried this, and it *does* fit. But it is really tight, so I would worry about heat right next to those vacuum lines off the selector knob. For the 1997 with the sliders I have no idea, but have heard that that unit is even more shallow than the knobbed version, so maybe that would be a good alternative.I have found that this mini-amp can also be fit behind and to the left of the glove box, but you have to be a magician to get it in there. This is so small that you also might be able to mount it to the firewall above the airbag sensor box at the very front of the center console, just behind the lower edge of the dash center bezel.Lastly, on my particular 2003 this amp can be made to fit on the tub wall behind the driver dash speaker. You have to use zip ties for that, but it works. I have seen this amp set up in this location in a couple of other TJs around here. It works okay, but I have the Polk component speakers, and this is where I mounted up my crossover on that side. There is not room for both, so far as I can see.I chose the Polk speakers because they are made for use on boats, they sound great and they are priced well. When I purchased them I did not know anything about RMS or the like, and I really like them. I do not want to add a powerful 4 channel amp or I will have to replace them. This small Alpine amp works really well with these Polk DB series speakers and still allows me to run the sub and amp I want with no problems. Further, if you want to add a 4 channel and more powerful speakers, this KTP-445 amp can be left in place as it does not use up any plugs other than the one used to hook the head unit up in the first place.For my TJ this little amp has been a solid, inexpensive upgrade that is pretty easy to hide, since we all leave these vehicles sitting open for any scumbag to "investigate" – stealthiness matters, and this amp is about the size of a walkie-talkie.

If you already own or plan to buy an Alpine head unit, the Alpine KTP-445A Power Pack Amplifier is hands down one of the easiest and most effective upgrades you can make.Installation is foolproof. This amp is designed to be plug-and-play with Alpine head units, requiring zero custom wiring or technical know-how. If you can handle basic plug in connections, you can handle this.If you're running stock speakers or aftermarket speakers equivalent to factory specs, this little amp brings them to life. You’ll notice an immediate boost in volume, clarity, and punch compared to running speakers straight off the head unit.Where this unit SHINES is if you have or plan to use a modest self or separately powered subwoofer for the bass, and then set your Alpine head unit’s high-pass filter (HPF) around 80Hz. By letting the sub handle the low frequencies and allowing this amp to use its power to focus on mids and highs, it absolutely punches way above its weight class. The result is clean, dynamic sound that stays clear even at higher volumes. Very clean and crisp.What It’s Not For: Don’t expect it to power heavy-duty, high-wattage speakers. That’s not its purpose. We’re taking 45 watts per channel.It’s a ridiculously simple, no-fuss upgrade that delivers noticeable improvement by itself and a game changer when paired with a separately powered subwoofer. Great job Alpine.

Installed this small class D amplifier along with an Alpine head unit in my 2006 Toyota Tacoma. I originally installed the head unit before this amp arrived and it literally took less than 15 minutes to add the amp. You simply unplug the connectors from that back of the Alpine head unit and plug those wires into the connector on the wire harness on one end of this amp, then plug the harness coming out of the other end of the amp back into the radio. It comes with a pretty long wire harness which allowed me to locate the amp behind the dash, near the steering column. This unit operates off the original factory wiring and did not require running any new power wires to the battery or fuse box. Very simple and cool design and it really helps to fill out the sound by increasing the output from the head unit from 18 watts to 45 watts. This small amp doesn't provide ground shaking thundering bass, but if your plan is to just install an Alpine head unit and either retain your factory speakers or upgrade them, it's worth the extra money to add one of these to the system. (Alpine also makes a version of this amplifier that has a universal wire harness that can be used with other brand head units. They take a little more work to hook up as they are not plug and play like this one is to an Alpine head unit).

I wanted a simple and quick way to add more volume to my current system, I have a Jeep Wrangler with the Alpine CDE-143BT, Polk Speakers front and back. This was truly plug and play, easiest upgrade I've ever done to any system. It increased the volume significant enough for me, it's not your window rattling boom, but just a clear loud system. Prior to install I could go to 20 on the volume knob, anything after that and I'd get a distorted sound. I put this up to 26 and the sound was clear and very loud, at least for me. Best of all, it's hidden, nothing to see, no power wires to run to the battery.I'm very satisfied