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Cool and Compact Amps

Sometimes size doesn't matter. You get big power from a little box with Alpine's Power Density Digital Amplifiers. Super-efficient Class-D technology allows these small-but-mighty amplifiers to run so cool they can be stacked together for a sweet multi-amp setup, freeing up valuable space in your car.

stackable up to 3 high

heavy-duty, clean power

The PDX-4.100 4-channel amplifier supplies a full 100 watts to each channel, plenty of power for even the most demanding component speaker systems. Switch to 2-channel mode, and you can send 200 watts to each of your subwoofers. Beefy internal components and clever engineering keep the power output strong and the noise low for superb fidelity and control. Adjustable frequency filters tailor the amp's output to your specific system.

High-quality connections

your description here

Front-mounted controls make post-installation adjustments a snap. Gold-plated RCA inputs and power connections resist corrosion and signal degradation. Nifty speaker wire plugs ensure a tight connection and guarantee that your speakers play in unison.

Product Highlights:

  • 4-channel car amplifier
  • 100 watts RMS x 4 at 4 ohms (100 watts RMS x 4 at 2 ohms)
  • 200 watts RMS x 2 in bridged mode (4-ohm stable in bridged mode)
  • CEA-2006 compliant
  • stackable installation design with front-panel controls
  • variable high- and low-pass filters (30-400 Hz, 12 dB/octave)
  • quick-connect speaker connectors
  • Class-D amplifier design
  • MOSFET power and output stages
  • fuse rating: 30A x 2
  • 4-gauge power and ground leads recommended — wiring and hardware not included with amplifier
  • 10-3/16"W x 2-1/2"H x 8-1/2"D
  • warranty: 1 year
  • Our 60-day money-back guarantee

My system has plenty of power. Who needs an amp?

You might think you don't need an amp because you have a 400-watt system in your car, or because your new stereo puts out 50 watts a channel. But those are peak wattage ratings, which may boil down to 15 or 20 watts per channel, using the more realistic RMS rating. An amp sends your speakers the power they need to deliver your music with clarity and impact, whether you're using factory speakers or high-performance components. And low-frequency reproduction requires lots of power, so an amp is an absolute must if you're adding a sub to your system.

Alpine PDX-4.100 Reviews

Average Customer Review:

9 Reviews

Saving to buy another

Written by: Anthony from Philadelphia on March 7, 2010

I had this beast wired to a set of SPS 600C somponents and Infinity kappa MKII components. I then wanted somethin different so I upgraded my SPS components to some 3 way components in the front and Infinity Kappa Perfect 6.1's in the back of my 07 Grand Prix. Currently as I type I have the Alpine PDX bridged to the components. Yes bridged! 2270 watts RMS to each crossover and its EXTREMELY CLEAN.No distortion!



Great Amp!

Written by: Darren from Clayton, NC on November 25, 2009

I paired this amp with a set of the Alpine SPX-13 Pro Components and SPR- 13C 2-Ways, even though this amp is only 100 Watt per channel, I have plenty of head room, and sound is awesome!!! I get goose bumps when I listen to certain songs...The sound quality is superb. If you want an audiophile system, you cannot go wrong with this amp and the other PDX series.



Very Impressive

Written by: Ryan from MA on August 29, 2009

I am very impressed with this amp. i have it powering two sets of 6.5" alpine type x components and they are crystal clear. amp was rated at 130 watts to all 4 doors. Very nice and compact. gets warm but never cuts out on me.



Great Amp

Written by: Ray from Philly on July 17, 2009

I just got this Alpine PDX 4.100 amp installed in my expedition and it's great. It powers 4 Alpine SPR 57C speakers and they get LOUD. When my subs are turned off i can put my volume to the max and this amp makes my car JUMP. People don't believe me when i tell them my subs are turned off when i put just my door panel speakers all the way up. Great amp, couldn't recommend a better one.



Love the amp, hate the mounting options

Written by: Rob from San Antonio, TX on October 27, 2008

I forked out money for this amp for threa reasons; 1 Power, 2 Size, 3 mounting options.

Well I guess 2 out of 3 aint bad . . or is it . . one of the big selling points of this amp - is the mounting options. Well I had pre-planned my install before purchasing this unit. I order everything and start my install. Then I get the boom lowered. ON the install instructions of the amp it states the amp must be installed level and horizontally. ARRRG!!! I had planned on the amp being installed vertically . . it clearly states you will void your warranty. All my pre-planning out the window.

I like the amp, it sounds great. But could have spent a lot less money for something a bit bigger.

Anyhow keep that in mind before you buy.

[Editor's Note: Thanks for bringing this to our attention Rob. This has been confirmed with Alpine, and our "Hands-on Research" has been corrected.]



Exceeds expectations!

Written by: Pete from Albuquerque, NM on July 24, 2008

I bought this to replace the two class AB amps that I was planning to install
since I was concerned about heat build up in the confined mounting space.

The build quality of this amp is superb. It mostly built from thick silver and
black anodized aluminum extrusions. The connectors are all top quality.
The plug in speaker terminals are quick, easy and secure. The power
connectors easily accept 4 ga. cable. It's too beautiful to hide away!

I'm running the amp in four channel mode. I am not using the built in
crossover filters since I have an Imprint processor in my system. The sound
quality is impressive, with tight bass, clear midrange and sparkling highs.

I give this amp my highest recommendation.



Alpine PDX-4.100

Written by: james from st charles, il on April 10, 2008

Top notch product.
this amplifier keeps
the music clean at a
very loud level.
very small and nice
design. i would
recommend this
amplifier to anyone
who is serious about
great sound in their



You get what you pay for!!

Written by: T-RAY from Summerdale, AL. on September 29, 2007

Crutchfield Customer Review (What's this?)

Best buy for your dollar! I also have this amp powering 4 type R speakers, and at only half power this amp performs wonderfully! My speakers are clear and loud, just the way I like it! High on the price, but high on performance (actual rms certificate 130 watts rms!!). It performs at 2 ohms just the same at 4 which is the whole PDX line. Excellent look an the size is unbeatable! It's smaller than a sheet of paper, which makes mounting options unlimited!! If you think it's too high on the price, think of it as never having to replace it price! I don't think any other amps can compete with size, power, and performance! Im now a firm beliver that for car audio Alpine is the only way to go! I own this and a PDX-1.1000, a type X 12, cde-9881 HU, and as I said the four type R door and rear speakers! I dont think I'll ever buy anything else but alpine! WAY TO GO ALPINE (APPLAUSE)!!!



Worth It

Written by: Tremain from Montpelier, VA on July 28, 2007

This is a nice amp. Its size makes it able to mount anywhere. Its just slightly smaller than a sheet of paper. I have mine mounted under my seat supplying my interior door speakers. All Alpine Type-Rs. Its solid and powerful with an actual RMS of 128 on the certificate from Alpine that came with it. If you can shell out the bucks I would buy this amp because of its size and power.



Hands-on research

What's in the box?

Download owner's manual

  • 4-Channel amplifier
  • Two 30-amp blade fuses (installed)
  • 4 Speaker quick connect terminals
  • Four 1-1/2" Self-tapping screws
  • 2mm Allen wrench
  • 4mm Allen wrench
  • Owners Manual (English/French/Spanish)
  • Customer Care Registration/Survey
  • Warranty sheet
  • Specification verification certificate

Product Research



PDX Amplifier Design: Class-D amplifiers boast higher efficiency, produce much less heat, and draw less current than traditional Class-AB amps. The PDX series is Alpine's totally new super-efficient power density design of full range class-D amps. They combine MOSFET power supplies, MOSFET final outputs, and a thermal management processor, along with a 4-Layer Glass Epoxy PC Board to create a high-end sound quality without the bulky heat sinks required by most amps with this much power.

STAR Topology: Alpine's unique STAR (Signal Transit for Accurate Response) Circuit PCB design provides a single common ground for all amp sub-blocks, preventing ground interference and minimizing internal noise.

Terminal Layout: For wiring convenience all the inputs and outputs on the amp are on one side.

Verification Certificate: The amplifier comes with a certificate that lists the RMS power output of the individual amplifier. It also lists the model number, serial number, test date, and the test conditions (14.4 volts, 4 ohms).

Speaker Connecters: The PDX series amps use a new Speaker Quick Connect plug to attach the speaker wires to the amp. Bare speaker wire, up to 8 gauge, is held in place by a set screw, the Quick Connect plug then plugs into the amp. Like an RCA jack, the Quick Connect plug uses a center positive layout, so it fits two ways and both maintain correct polarity.

Stack Amps: Because the PDX series design generates so little heat, up to three amps can be stacked and bolted together. All the amps in the series; PDX-2.150, PDX-4.100, PDX-4.150, PDX-1.600, and PDX-1.1000 share the same footprint, so they can be stacked together.

Notes: When stacking multiple amplifiers, do not install vertically or at an incline. Any stack installation other than parallel to the vehicle floor, invalidates the warranty.

LED: The top mounted LED Power/Status indicator glows blue when operating normally and red when one of the protection circuits engages.

Protection Circuits: This amplifier includes protection circuits to prevent damage due to the following conditions:

  • ambient temperature too high
  • supply current too high
  • short to ground
  • over voltage


Controls (front of unit): Once set, the controls are covered by a door.

  • Crossover Mode switch: set to HP (high pass), OFF (full range) or LP (low-pass), separate controls for the front and rear channels
  • Crossover Frequency: rotary controls used to select the crossover frequency, separate controls for the front and rear channels, variable from 30 to 400Hz
  • Gain control: rotary controls used to set the amplifier's gain according the level of the incoming signal, separate controls for the front and rear channels, continuously variable from 0.2V to 4.0V
  • Input switch: set to 1+3/2+4 (input 1 and 3 summed to feed channel 3, inputs 2 and 4 summed to feed channel 4, this makes channels 3 and 4 non-fading), 3/4 (channels 3 and 4 fed by inputs 3 and 4, maintains fader when head unit has front and rear line outputs), or 1/2 (channels 3 and 4 fed by inputs 1 and 2, no Y-adapters needed when head unit has only one pair of line outputs)


Inputs and Outputs (rear of unit):

  • Power and Ground terminals: power and ground terminals are gold plated set screw terminals, will accept up to 4 gauge bare wire, Alpine recommends 6 gauge minimum
  • Remote Turn-on terminal: gold plated set screw terminal, will accept up to 10 gauge bare wire
  • Speaker terminals: each of the 4 speaker outputs uses Alpine's Speaker Quick Connect plug
  • Line Level Input: 4 female RCA jacks, left and right for the front and rear channels, gold plated

Our Product Research Team

At Crutchfield, you'll get detailed, accurate information that's hard to find elsewhere. That's because we have our own in-house Product Research team. They verify what’s in the box, check the owner's manual, and record dimensions, features and specs. We stay on top of new products and technologies to help people make informed choices.