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Alpine PDX-4.100M

4-channel marine amplifier
100 watts RMS x 4

1 Review | 1 question - 1 answer

Item # 500X4100M

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Our take on the Alpine PDX-4.100M

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 on your boat.

Alpine Authorized Online Dealer

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 on your boat.

The PDX-4.100M 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. Weather-sealed 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.

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.

Note: Sorry, Crutchfield cannot ship Alpine products to Guam or Puerto Rico.

Product Highlights:

  • 4-channel marine amplifier
  • specially coated and sealed for the marine environment
  • 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 8-7/8"D
  • warranty: 1 year
  • Our 60-day money-back guarantee

What's in the Box:

  • 4-Channel marine amplifier
  • Two 30-amp blade fuses (installed)
  • 4 Speaker quick connect terminals
  • 4 Self-tapping screws (M4 x 40mm)
  • 2mm Allen wrench
  • 4mm Allen wrench
  • Owners Manual (Eng/Fren/Span)
  • Customer Care Registration/Survey
  • Warranty sheet
  • Specification verification certificate
  • Note to customers (regarding marine applications)

Alpine PDX-4.100M Reviews

Average Customer Review(s):

(1 Review)

Rock Solid, compact and reliable!

Lake RAT from Arizona on 3/22/2011

I've had this amp for over a year now and I have to say I love it! It's been very reliable and provides rock solid clean audio. I love the compact size and very solid and quality feel. This amp also got a bit wet at one point... I let sit to dry for a few days... powered up and still working today! Pros all around for this amp. Cons: seems to get quite hot when working long and hard BUT it hasn't ever entered 'thermal protection'. The control panel must be removed to access controls with a tiny allen key... not a big bother for me because I never adjust after my first setup (and shouldn't see a need to) but I could see this to be a bother for those who always like to adjust their amp gain. Install: 1997 Sea Doo Speedster Jet Boat Front: JL Audio M770-CCX Rear: Electro Voice EVID 4.2 (on the tower) Head: Kenwood KMR-700U Electrical: Optima Marine Blue Top




Hands-on research

Product Research

Inputs and Outputs


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.

Marine Ready: The Alpine PDX Marine-ready amplifiers are constructed from UV-resistant materials with corrosion-resistant hardware. The marine coating system helps the amp surpass the specifications for Salt/Fog (ASTM B117) and UV (ASTM G154/D4329) resistance.

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).

Crossovers: The front and rear channels have independent crossovers that can be set for high-pass, low-pass, or Off (for full-range operations). The crossovers are continuously variable from 30-400Hz with a slope of 12 dB per octave.

Speaker Connectors: 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. The other PDX Marine amp in the series, the PDX-1.600M shares the same footprint, so the two amps can be stacked together.

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, or over voltage.


Controls (front of unit): The controls are hidden and protected by a removable metal door. The door is removed by unscrewing one hex-head screw with the supplied Allen-wrench. The door can be secured once the controls are set.

  • 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

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

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Q & A

Customer Q&A

1 question already asked

I forwarded your question to an Advisor and they responded with the following: If you have 4 ohm speakers and bridge the amp down to 2 channels it will output 200 watts RMS and be 4 ohms. It won't be stable if you try and bridge a lower impedance speaker. If you would like to discuss further you can contact an Advisor directly by phone (1-800-324-9695) or online chat. [ Krissy  Mar 20, 2014 ]  Staff