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Polk/MOMO C400.4

4-channel car amplifier
75 watts RMS x 4

6 Reviews

Item # 107C4004

This item is no longer available.

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Our take on the Polk/MOMO C400.4

Polk Audio is legendary for building some of the best speakers in the world. Now, they've extended their engineering expertise and dedication to great sound to their new Carbon series amps. These bruisers are designed to give your system two big advantages over the competition: massive power output and outstanding SQ. Plus, thanks to Polk's collaboration with Italian motorsports accessories designer MOMO, they've got a distinctive, stylish look.

Polk Audio is legendary for building some of the best speakers in the world. Now, they've extended their engineering expertise and dedication to great sound to their new Carbon series amps. These bruisers are designed to give your system two big advantages over the competition: massive power output and outstanding SQ. Plus, thanks to Polk's collaboration with Italian motorsports accessories designer MOMO, they've got a distinctive, stylish look.

The Polk/MOMO C400.4 is built to give you maximum installation flexibility. You can wire it in four-channel mode to power full-range speakers, or bridge it to stereo for 200 watts x 2. Polk's Maximum Dynamic Headroom power supply means that you get power on demand — your speakers won't falter, even during massive musical peaks.

If you're building an all-Polk system, check out this exclusive feature: the C400.4 features a Pre-EQ switch, which optimizes the crossover and bass boost for use with Polk/MOMO component speakers. It allows you to amplify the tweeters and midranges separately, applying the optimal equalization and crossovers, so you can eliminate the passive crossover networks that come with the speakers.

Everyone knows that great sound is paramount, and the C400.4 delivers. But in the world of car shows and competitions, looks matter, too. And how does the C400.4 look? In a word, excellent. Flexible three-way wire management lets you route your cables to the left, right, or bottom, and the cover plate conceals the controls and all your connections for an uncluttered look. Combine that with sweet carbon fiber accents and removable end caps (take 'em off to save space, or to mount two amps right next to each other), and you've got one stylin' power plant.

Polk/MOMO Winner's Circle

Product Highlights:

  • 4-channel car amplifier
  • 75 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)
  • 2-, 3-, or 4-channel output
  • variable high- and low-pass filters (50-5,000 Hz at 12 or 24 dB/octave)
  • subsonic filter (15 Hz @ 24 db per octave)
  • Maximum Dynamic Headroom (MDH) power supply
  • Tri-way capable (Tri-Way crossover required)
  • 6-Way Smart System Protection (SSP) circuitry
  • high-density split-dome convection heat sink for extreme heat dissipation
  • Pre-EQ switch adapts amplifier for biamping Polk/MOMO component speakers
  • RCA inputs accept both speaker- and preamp-level input (To use the inputs as speaker-level, you must attach RCA connectors to your speaker wire.)
  • preamp outputs
  • fuse rating: 30A x 2
  • 8-gauge power and ground leads recommended — wiring and hardware not included with amplifier
  • 15-15/16"W x 2-9/16"H x 9-3/4"D
  • warranty: 2 years
  • Our 60-day money-back guarantee

What's in the Box:

  • Four-channel amplifier with two 30-amp fuses installed
  • 2 Spare 30-amp fuses
  • 2 Self-tapping screws (3/4" length)
  • 2 Allen-head screws (3" length)
  • 2 Allen wrenches (2.5mm and 3mm) 4 Self-adhesive rubber grommets
  • Owner's Manual
  • On-line registration card
  • Amplifier Power Authentication certificate
  • Quick-Start guide
  • Polk/Momo window decal (2-3/4" x 13")

Polk/MOMO C400.4 Reviews

Average Customer Review(s):

(6 Reviews)


andy from springfield, VA on 6/13/2007

ive had this amp for nearly 2 years, and its been pushed to its limits and even beyond sometimes... ive tortured it relentlessly and it won't give up, what a great amp! it's nice and clean, responsive and dynamic. multiple install options make this a sure bet for ANY setup. bi-amping option for polk speakers is a great feature, and the gain structure is pretty decent too. haven't had any problems like the ones described, EVER. pick one of these up and you won't be dissapointed.<BR>



top of line 4 channel

no from Davie, FL on 4/16/2007

i cant imagine this amp acutually being defective. but i guess that what those bad reviewers got. I have the mmc6500 after the 6x9's and the mmc5250. running into this awsome amplifier. i live in florida with no A/C and for a year this amp has been put to the test in weather that is almost always over 90 degrees plus 100% humidity. and it wont over heat and shut down. this is just a powerful amp, that is always going to perform.



Polk/MOMO C400.4

Tyler from Saratoga, NY on 3/31/2007

Crutchfield Customer Review (What's this?)

This is a unreliable choice based on the follwing, but after about 5 months mine blew up for no reason it blew both of the 30 volt fuses. It was not from a voltage spike because nothing happened to the Alpine Amplifier that was running off of the same distribution block. It was under warranty, which is a less than easy process because you ship it to sandiego with no phone number. When I got it back after they replaced the circuit board I connected it and it picked up engine noise, when it never did before. The one issue I have is that it puts a huge drain on you cars electrical system by pulling down 975 of dynamic power which is useless and leads to poor sound quality. Also when running 4 guage wire to the terminals it makes it almost impossible to put the end cap on to hide everything. I think polk mades excellent products but I have to say this is one of the worst four channel amps I have ever owned. I had a m series alpine which was equal in power and now I am running a 300/4 both amplifiers were superior in terms of sound quality and cooling. The fact that power doesn't double at 2omhs is a sign that it is set up to run at 4 omhs and will not function as well when running as a two channel. Also you will need to buy an aftermarket alternator due to the power drawn if running a Class D amplifier.



Nothing But Problems

Kenny from Los Angeles, CA on 11/30/2005

Crutchfield Customer Review (What's this?)

Bought this amp 18 months ago and had it professionally installled. <BR><BR>After it was installed, the installer said he was not sure but the left channels would cut out after 20 minutes of playing loud music. Otherwise the amp sounded fine.<BR><BR>After 3 months, the left channels had gone dead and the left side speaker (Polk db6500) were fried. <BR><BR>Paid $60 to have the amps and speakers removed and $20 to have them shipped back to Polk in San Diego for replacement/repair.<BR><BR>One year later, the same channels/speakers made a crackling sound when playing. Bought a second set of Polk db6500 speakers and had a professional installer swap out the fried parts (the speaker crossovers). <BR><BR>The professional installer switched the outputs on the amp and the crackling switched to the other side so the problem is in the amp again.<BR><BR>Obviously, the amp was bad when purchased and was not properly repaired when returned to Polk.<BR><BR>I tried calling Polk in San Diego to get a RMA number, but no one answers the phone and, of course, I cannot get a RMA number over voicemail.<BR><BR>I have now spent $150 in labor to have the amp taken in and out of the car for service and purchased two sets of front speakers.<BR><BR>In addition, the system has been down for about 3 weeks while being repaired.<BR><BR>If you are considering purchasing this amp, I reccommend you consider another brand/model.<BR><BR>



No complaints at all

pwatanab from Los Angeles, CA on 8/20/2005

Crutchfield Customer Review (What's this?)

Very solid piece of equipment. I have mine driving Polk's 6.5 components and their 10 inch sub (both MOMO), and it is more than adequate even with the gain barely half way up. Performs as if the power ratings are very conservative. I haven't been able to get it to go into thermal shutdown no matter how hard I push it. Every bit as good as my previous amps from PPI.



Buy it.

Brian from FPO AP Japan on 5/21/2005

Crutchfield Customer Review (What's this?)

Amazing amp! I listen to a wide range of music, from classical to heavy metal, and I'm obsessive about tone and clarity - I want to hear Yo-yo Ma's bow on his cello, and Hammet and Satriani's picks hitting the strings. I've got this amp pushing Polk/Momo MM6's in front and Infinity Kappa 6-3/4's in the rear for fill. You get incredible clarity and depth with this amp. I've installed several systems for friends, and for the price this is the best multi-channel amp I've found. The thing looks great and is very durable and generates little heat. Removable endcaps, control cover, and cable routing cutouts underneath control cover allow great freedom in mounting and clean custom installs. I can't recommend it highly enough.




Hands-on research

Product Research

Inputs and Outputs Notes


MDH Power Supply: Polk Audio's Maximum Dynamic Headroom (MDH) power supply allows the amplifier to deliver more instantaneous power peaks, easily driving the speakers during musical peaks.

Protection: This Polk/MOMO amplifier features 6-Way Smart System Protection (SSP) circuits. The SSP circuits include protection against Power and Ground Reversal, Thermal and Short Protection, Current Overdraw, and Low Impedance. When a problem arises, the amplifier goes into an Auto-standby mode to ensure safety, reliability, and durability. Three LEDs indicating Power, Thermal and Short/Low impedance protection are located on the amp's top panel.

Heat Sinks: The high-density, split-dome convection heat sinks provide more surface area than standard fin-type heat sinks for better heat dissipation.

Removable Cover: The amplifier has a removable cover which conceals the power and signal terminals and amplifier controls. Once the amplifier controls have been set, the cover can be reattached to help provide a clean-looking installation.

Switchable Inputs: The RCA input can accept either line-level or speaker-level input signals. For speaker-level inputs, you will need to attach RCA connectors onto the speaker wires, and move the switch to "High". Note: RCA connectors are not included with the amplifier.

Built-in Crossovers: The C400.4 amplifier is equipped with variable Low-Pass and High-Pass crossovers to give you the control you need to power virtually any type or size of speaker from tweeters to component systems to subwoofers. The front and rear crossovers can be independently configured using the following controls:

  • Slope: This 2-way switch allows you to select a 12dB per octave or 24dB per octave slope.
  • Frequency Multiplication: This 2-way button lets you select x1 if you want a crossover frequency between 50Hz and 500Hz, or x10 if you want a crossover frequency between 500Hz and 5000Hz.
  • Crossover Frequency: This rotary dial allows you to choose a crossover frequency between 50Hz and 500Hz when at x1 or between 500Hz and 5000Hz when at x10.
  • Crossover Mode: This 3-way switch lets you select Low-Pass (LP), Off, or High-Pass (HP) depending upon the type of speakers you are driving with the amplifier.

Pre-EQ: The amplifier also features a one-button preset crossover and EQ optimization circuit called the Pre-EQ for use with Polk/MOMO component systems. The purpose of the Pre-EQ is to allow you to bi-amplify the Polk/MOMO MM6 component speakers (item # 107MM6) with the C400.4 amplifier, eliminating the passive crossover networks supplied with the speakers. Using the Pre-EQ, the front channels are driving the tweeters and the rear channels are driving the woofers. (See below for Pre-EQ specifications.)

Subsonic Filter: The amplifier has a subsonic filter (15Hz @ 24dB per octave) to eliminate super-low frequencies which can rob amplifier power and cause damage to speakers. Note: The subsonic filter is only activated when the Crossover Mode Selector switch is in the LP position.

Polk/MOMO Amplifier Power Authentication: A certificate is included with the amplifier to attest to each individual amplifier's power performance. This Amplifier Power Authentication indicates whether the amplifier passed the standards in Total Quality, Response and System Protection. It lists the amplifier's serial number, and the amp's actual power output alongside the amp's rated power. (For example, the specific amplifier reviewed by Crutchfield had a power output of 85 watts RMS x 4 @ 14.4V at 4 ohms. The amp is rated at 75 watts RMS x 4 @ 14.4V at 4 ohms.)

Compact Size: The C400.4 amplifier features a relatively small footprint for compact installations. The End Caps are removable, making the amplifier only 15" wide, and allowing you to seamlessly butt together multiple Polk/MOMO amps.

Cable Management: The End Caps have side vents for routing power and ground wires to one side and speaker and signal wires to the other side. The gap between the amp base and the removable plate also provides a channel for routing wires.

Inputs and Outputs Notes

Speaker Outputs: The amplifier has set-screw speaker outputs for 4 speakers. The terminals accept up to 8 gauge wires and require a 2.5mm Allen wrench (supplied).

Pre-Out Terminals: The amplifier supplies two pairs of stereo female RCA-type pass-through jacks to allow you to easily daisy-chain additional amplifiers without the use of Y-connectors. One pair passes through the input signal from the front channels, and another pair passes through the input signal from the rear channels.

RCA Inputs: The RCA inputs can accept either a low-level (Line) input signal or a high-level (Speaker) input signal. To use the high-level input, you must attach male RCA connectors (not supplied with the amplifier) onto your speaker wires and move the Input Type Selector to "High".

Power Connections: The power and ground connections set-screw terminals will accept up to 4 gauge wires. The set screws require a 3mm Allen wrench (supplied). The remote set-screw terminal accepts up to 10 gauge and requires a 2.5mm Allen wrench (supplied).

Remote Bass Gain Module Input: The amplifier is equipped with an RJ-11 input (marked "Remote") for an optional Remote Bass Gain module. The module, available from the manufacturer, allows you to dial in the precise amount of bass you desire from the drivers seat. A 19-1/2' cable is supplied with the module to connect the module to the amplifier. Note: The Remote Bass Gain control only works on the rear channels and only when the amplifier's Crossover Mode Selector is in the "LP" position.


Pre-EQ: When using the C400.4 amplifier to bi-amplify the Polk/MOMO MM6 component systems, the specifications of the Pre-EQ crossover and optimization circuit are as follows:

  • Front (tweeters):
    • Filter Function: High Pass
    • Corner Frequency: 4.0kHz
    • Slope: 12dB/octave
    • Filter Function: Shelf
    • Corner Frequency: +2dB @ 12.1kHz
    • Bandwidth: 6dB/octave
  • Rear (midranges):
    • Filter Function: High Pass
    • Corner Frequency: 38.4Hz
    • Slope: 12dB/octave
    • Filter Function: Low Pass
    • Corner Frequency: 2.82kHz
    • Slope: 18dB/octave

Our Product Research Team

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