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by Bill Braun

Reviewer Extraordinaire

on October 31, 2013
Let us all pay homage to the mighty, tiny, Class D amp.

Every major car audio amplifier manufacturer is offering nearly as many (if not more) in Class D amplifiers than they are in Class A/B. Kenwood, JL Audio, Alpine, Rockford Fosgate and Kicker just to name a few. Most every other brand will follow suit.

Some competitors to the Alpine PDX-M12 are the Rockford T1000-4ad and the JL Audio HD1200/1. All of the amps are around the 1,000 to 1,200 watt mark and about $1,000 to $1,200. The amplifiers are all very close to the top end each manufacturer offers, and they all have very similar features.


The Alpine PDX-M12 Mono Amplifier body is made from very solid brushed metal. The black on black look is sleek, with a sheen that makes it look new all the time. It’s a turn on to be sure, and despite the fact that the upper trim piece is removable, it still looks like it’s a combination of an amplifier and something out of the Transformer movies. Like I said, it’s a turn on.

The trade-off of a black high gloss finish is dirt and fingerprints. How many of us have owned black cars, black-trimmed TV’s or some other obsidian object? There are few things on this Earth that look better than a freshly waxed black car until a solitary spot of dirt gets on it. Your OCD comes out from some dark, hidden place. You must clean it. You will go into convulsions if you don’t. That’s your reward for purchasing a shiny black product-of-your choice, so keep a rag handy if it’s visible when you open the trunk.

You can stack these amplifiers, which Alpine claims will save room in your trunk. It makes sense to do that in many cases, plus it just looks cool. The curves of the amp seem to invite the stacking idea, and the blue LED lights on the front and top of the amp only help the coolness – and I am certainly a fan of adding to the coolness.

The fuse and power sections are well marked, even to the untrained eye. The speaker section is equally easy to identify, as is the over all. Alpine is one of the few companies that decided to build on the idea of easy identification by creating two completely different plugs that snap into the body of the amp.

We love the idea, providing it’s well executed. The metal power plug has plastic-shrouded connections for power, ground and remote turn on. From a design standpoint, it makes the wiring process a bit easier as you don’t have to have the foresight to extend wires 20 feet long through the bowels of whatever car you’re working on, strip them, then try to extend the wires - fitting them perfectly into the receptacles of an already mounted amplifier. By the way – you’re usually contorting yourself a bit while bent over a trunk while doing it. Did I mention its usually pretty dark in there as well?

No more. Strip the wire. Twist the bolt. Snap it into the amps power receptacle. Done. Laugh at the other installers with the spare time you just earned.

The speaker connection is a similar, but not an identical plug. Unlike the power connection, this plug has a beveled bit of plastic around the entrance. The end of the connector is close to a USB shape, only a bit bigger. You can easily fit one (or more) 14 gauge wires into the each hole, and the concept that followed the power connection is mimicked logically on the speaker connection.

Next to those connections you’ll find the plug for the remote bass control and the RCA Input and RCA Pre Out pass through connections. The connectors are labeled, so nothings hard to figure out here. If you add the Alpine RUX-KNOB Bass Boost Level Controller, here’s where you’d add it.

Turn the amplifier around and unscrew the bolt that attaches front plate will reveal the switch panel. The gain, subsonic filter, lowpass filter and input voltage switch are all here. Everything’s easy enough to read and understand what they are.

The mounting points are hidden under the trim ring, which is something I am a big fan of. It shows a fair amount of foresight, as I don’t like to see anything but a clean rectangle sitting in the trunk with blue light staring back. You’ll also find the mounting points for the stacking plates here as well.

Build Quality

The trim panel is attached by a single screw, which holds the panel on adequately, though there is room for improvement by making the latching points beefier or adding a rubber gasket to both protect the area and create a better seal. I’m not sure how much it would take vibration-wise to loosen the panel, but I don’t want to find out the hard way either.

The crossover and gain section take a bit of effort to change. The switches are almost completely flush with the metal, so you’ll likely need a small screwdriver to move them. Despite the work, the stiffness is actually a good thing. Loose knobs stand a small chance of moving over time in an environment that constantly bumps and vibrates. I see people in competition settings double-checking things like this to make sure their car is “dialed in.” It’s not accidental.

What I didn’t like was how close to ground level the controls sat. There seems to be plenty of room on that panel to raise the height of these controls, but they were placed low enough that you may have to make adjustments at an angle with a screwdriver, which to us is an unnecessary inconvenience. Just be careful when doing this so as not to scratch the amp.

The power and speaker plugs seem to be following a trend of their own – that being the plugs are separate from the amplifier. The purpose seems to plainly pointed at making your life a bit easier, via making the installation process one that doesn’t involve being a contortionist.

The power and ground plug is a thing of beauty. It’s well labeled and impossible to install the wrong way. If Alpine had designed this poorly it could at least pop a fuse and at worst damage the amp. Thankfully, they were on their game, as they usually are. The small tab in the center of the connector helps to make sure the connection is solid – and it is. Once installed, trying to move the connection around is nearly impossible, which is more than a little reassuring.

The speaker connection is a bit different that its counterpart, which was odd to us. The connection that plugs into the mono amp is labeled on the connector, but unlabeled on the body of the amp. The theory is that you can’t mix up positive and negative when there’s no other channel to mix it up with, but were used to being told which is plus and minus, so it took us aback.

To top that off, the biggest issue was a lack of a locking tab on the speaker connection. When you plug the speaker connection into the amp, the USB-shaped plug forms a good – but not great – connection to the body of the amplifier. While I doubt it would happen, it’s not impossible for the speaker tab to simply come out during an extraordinary amount of shaking. I don’t know what – if any – damage that would result, but why not employ the same locking tab I loved so much on the power side? It could have easily done the trick here, but for reasons unknown, Alpine simply didn’t follow through.

If you are truly worried about it, our suggestion is to create a simple strain relief loop in the speaker wire – two wire clamps and two screws is all you’d need to add a bit of protection.

The fuse block is well laid out with four 25-amp fuses. I like that the fuses aren’t so close together that you need a pair of pliers to remove a fuse if needed. Handling 100 amps of current is something we’re betting Alpine takes quite seriously. If you don’t want to over-tax your factory power system, consider adding a secondary battery and isolator. If your factory lights look like Morse Code when the bass starts to pump then yes…you’re taxing your factory power system.

The indicator lights are a blue that you almost automatically associate with Alpine. If you know even a little about their history, and turn the predictable red if something goes wrong like temperature, a short or power overload occurs.

The amp body is very solid and smartly built. Keeping it clean is pretty easy once the amp’s installed. Were fans of both the amp mounting and stacking systems, with easy access to both systems once the trim ring is removed. I was very thankful the amp stacking hard came with the unit. There’s nothing so annoying as spending an extra couple of bucks on hardware I think should have come with the amplifier to begin with.

One note here: be sure to use a protective sleeve on your drill (also called a drive guide) when installing the amp to the vehicle, amp rack or box. You should be doing this on any amp install, but especially on amplifiers where you run a small – but manageable - risk of scratching the body of the amp during installation.


Reading the details of this amp on the Alpine website brings up some head turning data. Claiming some of highest damping factors I have ever heard of on a mobile amplifier was the first thing that caught my attention. The other stat was a 122dB Signal to Noise ratio at rated power.

In plain English, this amp says it’ll deliver some of the cleanest, most articulate signal in the mobile audio market.

The amp also features a subsonic filter. The purpose behind a filter like this is to prevent the speaker from wasting energy by creating sounds below what it’s designed to play. This also saves power, creates a significantly better sound and inevitably helps the speaker last.

The PDX-M12 also has a pass through set of RCA terminals. These terminals help to distribute signal to other amplifiers without running new RCA cables from the radio. The amp re-amplifies the outgoing signal, allowing the next amp in line to get the same power as it got from the radio. It also means that you can use a number of amplifiers without worrying about the signal degrading.


The amplifier delivers more power than many subs can handle, and does so with a punch I can accurately describe as “anvil-esque.” It's bloody loud, is what I’m getting at.

Surprisingly the amp delivered decent levels of clarity when I wasn’t playing something designed to cause a seismic event. Listening to the IASCA Sound Quality CD the amp did a good job giving, clean solid bass with minimal “muddiness.” I believe this is mainly thanks to the improved output stage the PDX series offers.

It's clean. It's loud. It delivers exactly what it says it will and does so non-stop. What more can anyone say?

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