Sunday, August 1, 2010

Alpine PDX-F4 Four Channel Class D Amplifier Review

Alpine is a constant in the name of quality car audio gear. Up for review today is one of their Class D four channel full range amps, the PDX-F4. Alpine has continued with their innovative products. This amplifier does more then just power your speakers. It does so using some unique features to deliver excellent quality sound to your speaker.

Alpine's PDX Series incorporates their Power Management Circuit. The Power Management Processor does it's magic controlling the performance of the amp. This control includes the performance, monitoring voltage, temperature, and output to maintain uninterrupted power and music to your ears. The temperature detection is for the power supply, output stage, and heat sink. The voltage detection is for under and over voltage, and DC offset. Current detection is for over and under current, and short-circuit. The Power Supply Management also includes power supply, signal stage, and output stage control. What this all means is that your amp won't turn off due to heat. If the amp gets too hot, the output power will decrease until the amp cools down. Once the amp if cool, the power output automatically increases to the previous level. The same thing happens if the circuit detects a low battery condition.

The PDX-F4 also has a stacking capability. That does not just help to save trunk space. One might think that stacking would hurt the amps ability to dissipate heat. But the stacking of the amps together actually connects the heat sinks together to help share the cooling.

The connectors are also quite unique. There is one for the battery, ground, and remote turn-on leads. And then there is one for each of the four channels. It makes for a simple installation. Just tighten the wires down in their appropriate connector with the internal hex screw. After the wires are tightened down, the connector plugs into the amp. And amazingly, it does not matter how you plug in the positive and negative speaker wires. The connector has it labeled which hole to put in the positive and the negative wires. But when you push the connector into the amp, you could have the power wire on top, or the ground wire on top. But amazingly it doesn't matter which way you plug it in.

The specs are pretty good for it's size. It is rated at 100 watts x4 at 14.4 V. And one thing I like about Alpine is the Verification Certificate. When it comes to amplifiers, it's easy to wonder if your amp actually puts out the power it is supposed to. With the Verification Certificate, you know how much you are getting. The one I received actually put out 121 watts to each channel at 4 ohms at 14.4 V.

The rest of the specs also look good on paper. THD + N is 0.05%, s/n ratio is 115 dBa and 95 dBa at 1 W into 4 ohms. The Frequency response is 5 Hz-100 kHz. The built in crossover frequency has the options variable, HPP, LPF, and off. The input sensitivity is selectable from 0.2 V to 4.0 V. The dimensions are only 10 1/8" x 2" x 7 9/10" and the weight is 2.87 kg.

Sound quality was also extremely good. With the features listed above to improve sound quality, I was not surprised. Junior Wells: Why Are People Like That, the sound was very clean with nice dynamics. The noise level was also very low, and with extremely low inaudible distortion. The pitch definition and dynamics were great, especially with the harmonica. In Eric Bibb's: Don't Ever Let Nobody Drag You Down, the vocals and piano were very natural sounding, especially with the female vocals. The harmonics were also great.

Testing with some more popular music also gave me a smile. With No Doubt: Hella Good, I could hear the great channel separation. Pitch definition was very good and the music was very detailed. In Justin Timberlake's Future Sex/Love Sounds: SexyBack, I again heard great dynamics with the snaps, and the vocals were very natural sounding. The bass beats were brought out in my midrange drivers with authority.

Having experienced Alpine's quality, I'm glad to see that some things don't change. I was pleasantly not surprised with the PDX-F4. The specs and features showed a great amplifier and was supported by the sound it delivered. It should be on everyone's short list. Based on it's features and performance it has earned our Highly Recommended award. Reference gear used was Kenwood Excelon KDC-X991 receiver, Kenwood Excelon XR-S17p components up front and Rockford Fosgate Fanatic HPC1206U coaxials in the rear. For complete specs and more info, check out their website at: