Alpine PDX-F4 Four Channel Amplifier

Product Details
Manufacturer: Alpine
Website: link
Typical Selling price: £349.95
A second generation of the PDX or Power Density amplifier concept. These are 20% skinnier than the first lot and like them, can be stacked with an optional kit so you can have a solid wedge of power in a tiny space in your car. This is the four channel PDX-F4 model and sports four lots of one hundred watts at both four and two Ohm impedances. It can of course be bridged but it is an unusual design in that as well as its great compactness, it also uses the cunning quick release speaker plug system Alpine introduced on the first generation. The power and ground/trigger wire connector is also on such a system, so if you avail yourself of the customisable colour rings, then you can change the amp easily without undoing and then re-doing your wiring for cosmetic reasons. You could simply unplug and replace a single four channeler like this one for a six channel design and add two speaker wires, then stack a mono one on top of it for bass use. Very neat and tidy, the bass ones can also have an accessory remote bass volume knob to mess about with if you like that. Many Alpine buyers do not, so it is an optional accessory you ain’t paying for in the amp’s affordable price.
And that’s what has got this reviewer erect, as if one is to accept the entirety of Alpine’s techno-speak, then this is one special development. It isn’t just smarter and prettier and skinnier. It is also reckoned to be a tour-de-force once-every decade grade big fat step forwards in this type of amplifier’s design. For it isn’t claimed to be merely ‘good’. It has specs that mean it aughta be all the way into awesome. And that meant in a truly British way to indicate something more than merely very good. Not in the American way, as in ‘That burger was awesome!’
– Class D Full Range
– 4 x 100w RMS @ 4 Ohms
– 4 x 100w RMS @ 2 Ohms NB: The same as 4 Ohms
– 2 x 200w RMS @ 4 Ohms bridged
– CEA-2006 compliant
– Stackable installation design with front-panel controls
– Variable high- and low-pass filters (30-400 Hz, 12dB/octave)
– Quick-connect speaker connectors
– Mosfet power and output stages
– Aluminium panel heatsink with stack system for stacking also customisable trim rings
– Adjustment controls hidden under a metal plate with Allen headed retainer bolt
– 8Ga. Power Terminals with Allen headed grub screw bare wire socket connection on quick-connect system
– High cable diameter speaker connection plug and socket system for speakers, as well
– Adjustable input sensitivity: 0.2V to 4.0V
– Stereo & bridged operation
– Bass remote control ready control knob is an accessory
– Frequency response 5Hz – 100kHz / 0dB to -3dB (Reference: 1W into 4 Ohms)
– Signal to Noise Ratio: CEA 2006 S/N Ratio (IHF A Weighted, Reference: 1W into 4„¦) 98 dBA – equivalent to 122dB on rated power
– High/Low Pass Filters; one per pair of channels –  30Hz to 400Hz (@12dB per Octave)
– Fuse Rating 30A x2
– Dimensions: (WxHxD mm) 257 x 192 x 50.8 (20% thinner than Gen1!)
Review by Adam Rayner
Alpine Electronics have always been at the very forefront of mobile electronics cunning. They may not be as big as Clarion but they go every bit as far up the awesomeness scale and indeed, for a while were even able to market their mad-end F#1 Status line in the UK, where Clarion’s maddest kit has been resolutely USA and Japan market only for some years. (I gather that if I can get a group buy of 800 headunits that it becomes economically viable to import and support these top end machines any orders?)
But they have always been beavering away and every now and again, they go from simple Kaizen (or the Japanese word for a continual and gradual improvement) to a Kaikaku (or revolution) and that is what I gather has happened here. It’s a decade-epoch grade change to a product we thought we knew.
I have been privy to some research and development reasoning and aims and stuff from Alpine real proper ‘things I am not at liberty to discuss’ and so was looking forward hugely to doing this review. I have rigged up the long term resident big oval speakers in their ply enclosures. They have a tiny compression driven horn tweeter in them and are absurdly good as in-your-face near field monitors but automotive rather than studio. They would of course be excellent for surround 5.1 in-car use but would be as reviled as any distracting-to-the-rear purist SQ Hound if they were in your parcel shelf!
Also, and being at risk of irritating the Alps guys a tad but in the solid interests of utter independence, I used a set of Pioneer’s better coaxials, also in for a test. They have big fat meaty passive lumps (capacitor and an inductance coil I think with an iron core I’ll check before I write them up!) stuck in their frames, bigger than those supplied with the mighty Vibe QB69! And in which lies the difference between TS-E1702i and 1702iS. They have injection moulded matrix Aramid fibre with Basalt as against glass fibre composite cones and the tweeters, despite being a coaxial design, actually have small chambers in their behinds, like very posh home units of the more enlightened.
And of course test music has to be the hoary old chestnut that is the sixth disc Focal gave away under their Spirit of Sound collection. I have played it to death and know every note. There are nuances, and details that simply go AWOL through ‘normal’ systems and hear this disc in say Brain Parton’s Porsche or Lee Thomas’ Astra or any of the Morel-equipped EMMA SQ hounds and you will hear edges and feel emotional impact the better the more fabulous the system. It’s a recording that keeps on giving.
Now reviewing can be seen as complex, with all the different bits in a system. What are you really ‘listening’ to? So what you do is reduce it into lumps of ‘known good’ kit. I know the tweeters in those ovals and how they sound on many amps. I know the disc inside out and I enjoyed the Pioneer ‘Specials’ a great deal and wanted to know if the PDX-F4 amp could scintillate even with what are still affordable speakers. As against a �1,700 set of limited edition Morels! And I found myself dissecting the speakers and even the tracks instead of paying attention to the amp at first and that takes a very special amp indeed. It was so clean and accurate, I could hear the limits of the rest of the kit really well, which sounds daft but is a truism!
And to be blunt, while I was ready to be impressed (or else rave about the new skinny size and how cleverly engineered they were and how I love the new trim rings) I was still startled as hell. This amp is bizarrely clean, tight of grip (It has a damping factor bigger than a 1st Gen HiFonics Colossus) and sweet of note. I hate the hidden crossover switches being so cheap but adore that they live under a solid slab of billetty-feeling Ally that fixes with an Allen headed fixing. (The Japanese call them Hexagon wrenches.)
It was just delicious and I found myself doing that classic listening to it for fun thing and gouching out and leaving it to late to do the copy! The Alps guys have been champing for this particular reviewer’s opinion and I have been fretting and putting it off. But that was daft as it is a Ronseal job. Go see the page of stuff about it here.
http://www.alpine-electronics.co.uk/products/product-singleview/pdx-amplifiers/pdx-f4.html
And have a good read. As far as I am concerned, it is truly a Kaikaku of Seven League Boots proportions. Class D can be HiFi and while there have been some domestic units of mind bending cost that have proved this in the home audio world, Alpine have one design here that will work in the toughest real world do-it-till-your-car-dies conditions and yet costs stupidly low amounts versus some really Big Sexy and Important brands in US based ice and above all, sounds absolutely High End.
Ethereal, pretty and spacious? Yes. Now I just want to give the bloody bass amp a pull through and see if it is as superb. Oh yes and one last thing, it’s rated at a 100w per channel RMS and each and every one gets a birth certificate and a real power test figure. Our one was opened and broached by me, so NOT stock-searched for a bad ass one but was measured at a whopping 128 watts! That 800 watt peak of biff on bass hits they refer to on the packaging? That’d make that an under-estimate!
This is a peak of a kilowatt in a box, split four ways and I predict a soon-to-be cult item with stacks and colour coded arrays of them appearing in show cars in seasons to come. Yummy and reference with it, and offering stupefying VFM
Stuff on here is rated according to sheer excellence but also as to its quality of it’s type, or there would be no point in reviewing the cheaper stuff for them’s as needs to care more than the rest about price. (And that was me!) And while this isn’t a four grand Thesis, I will give it a ten for the SQ as the S/N is pushing limits. The power is a ten as well and so is the sexy slabby billetty build and VFM aughta be 11. Feature count is simple low-frills but that doesn’t take the total out of the top end zone.
All of which adds to up to this being a state of the art class D car amp of four channels and as such we are going to award it just that very rare accolade!
Sound Quality 10.0
Power Output 10.0
Features 8.0
Build Quality 10.0
Value For Money 10.0
Overall rating 9.6