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Rockford Fosgate Prime R400-4D

4-channel car amplifier — 75 watts RMS x 4

13 Reviews | 2 questions - 4 answers

Overview

Our take on the Rockford Fosgate Prime R400-4D

Rockford Fosgate packs more power per square inch into their Prime Class D amps than almost any other amplifier made, so you can put more music power in your vehicle's limited space. Your music will play loud and clear with one of these reliable and cool-running amps.

Rockford Fosgate packs more power per square inch into their Prime Class D amps than almost any other amplifier made, so you can put more music power in your vehicle's limited space. Your music will play loud and clear with one of these reliable and cool-running amps.

4-channel versatility
The R400-4D 4-channel amp puts out 75 watts RMS to each of your full-range speakers or components, giving them plenty of juice to rock. You can also use the front channels of the R400-4D for your front speakers while using the rear channels bridged to run a sub with up to 200 watts RMS. And, of course, you can bridge the amp to 2-channel mode to drive a pair of subs.

Clean power, extensive controls
Rockford Fosgate designed Prime amps to deliver Power Output Without Excessive Regulation (POWER), which means they'll respond quickly to the peak demands that you may throw at your system. High- and low-pass filters, along with Rockford Fosgate's famous Punch bass boost, let you tune your speakers for maximum performance, so your driver's seat will become your favorite place for listening.

Product was endorsed by Crutchfield for my application. The instructions to install were right on. It was a very happy ending and a SUPERB upgrade. Thanks for all the product support.

Paintxpert, Stratford, CT

What's in the Box:

  • 4-Channel amplifier
  • 3mm Hex key
  • Installation & Operation Manual
  • Amplifier Verification Certificate
  • 4 Self-tapping screws (length=1-5/8")

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 bridged output at 4 ohms (4-ohm stable in bridged mode)
  • CEA-2006 compliant
  • variable high- and low-pass filters (50-250 Hz, 12 dB/octave)
  • variable Punch EQ bass/treble boost (0-18 dB at 45 Hz and 12,000 Hz)
  • Class-D amplifier design
  • MOSFET power and output stages
  • frequency response: 20-20,000 Hz
  • preamp inputs and outputs
  • 4-gauge power and ground leads recommended — wiring and hardware not included with amplifier
  • no onboard fuses — when installing multiple amps in a system, an additional 40-amp in-line fuse between the distribution block and the amplifier is recommended
  • 9-1/8"W x 2"H x 7-3/8"D
  • warranty: 1 year
  • Our 60-day money-back guarantee
Reviews

Rockford Fosgate Prime R400-4D Reviews

Average Customer Review:

13 Reviews

Great product, great instructions, great sounding!

Written by: Paintxpert from Stratford, CT on April 23, 2016

1969 Mercury Marauder
Crutchfield Customer Review (What's this?)

Product was endorsed by Crutchfield for my application. The instructions to install were right on. It was a very happy ending and a SUPERB upgrade. Thanks for all the product support.

Pros: Great sounding product that was easy to install. Thank-you for all the product support.

Cons: None so far that I can see.

Great speakers

Written by: Austin B from pittston, PA on January 29, 2016

Speakers are great! They fit perfect in my 2004 Jeep Wrangler roll bar... There being powered by a Rockford fostgate prime amp.. I am very impressed with the sound quality crisp highs! And very good mids in the stock Jeep Wrangler pods. They screw right it and fit perfectly.

Pros: Sound quality is great! Crisp highs and very good mids. Fit right in my jeep wranglers speaker pods.

Cons: Absolutely none

Cool AMP - Small But Quality

Written by: jffp from Philippines on January 25, 2016

I've setup with AVH x5750BT Head Unit, with Focal 165F and JL Audio 12" W1 v3 Subs! Great sound and clarity! feel all the bass and power !

Pros:

Cons:

meh

Written by: Bill M from Georgia on September 8, 2015

Crutchfield Customer Review (What's this?)

This amp makes me wish I'd never started this upgrade in the first place. I'm sure some people have had good luck with it, but I got my whole install done, hooked up the last RCAs to it, and they slipped right off. They are Stinger 6000 interconnects, and I've read a hundred reviews saying how great they are, and how tight, but on this RF amp, they come right off. I was just doing a first test of the system, engine off, listening, and the speakers cut out. The plugs had vibrated off in a matter of a couple of minutes, with just the sound causing it. When I told Crutch about it, they naturally said it was the interconnects (which I bought locally, instead of from them). Nobody I've talked to on several forums, and Amazon have had this problem. I guess the only solution is to rip out everything and start over with different RCAs. I think I'd rather just not bother, drive the car off a cliff.

Pros: The expectation of it working was great.

Cons: The reality sucked.

Rockford r400-4d

Written by: mike88688 from Pompano beach, FL on July 19, 2015

Crutchfield Customer Review (What's this?)

Produces amazing sound quality when paired with Rockford subs and speaker setup

Pros: Extremely good quality and sound

Cons: Could use a little more tuning capabilities

Didn't work properly

Written by: DG from San Antonio on August 12, 2014

Crutchfield Customer Review (What's this?)

used to power 4 speakers, had it professionally installed. 2 of the speakers didn't work at all and the problem was traced back to the amp. Ended up just buying a different one from the instaler

Pros: none

Cons: quality

do not buy

Written by: David from Oklahoma City on June 10, 2014

Bought this amp 2 years ago. It is an awesome amp when it worked. It is hooked up with all professional wiring. I only had the front channels hooked up and were running at half gain. It is hooked up to a infinity kappa component system and sounded awesome at just half gain. Just recently it stopped working. Power light on but no sound. For this price point, with half gain, 1 channel ever used, and in a vehicle that is rarely driven this amp should not be broke. Ive had RF amps that lasted years longer at max power for extended periods of time. Purchase a different amp or get a extended warranty. Tried to get it fixed but for $150 not worth it.

Pros: Sounds great when working.

Cons: Broke after minimal use. Guess thats why its only a year warranty. Just like a car, they know how long to do the warranty because after its out you will have problems.

Rockford Frigate Amp

Written by: John D. from Chesapeake, VA on March 18, 2014

Crutchfield Customer Review (What's this?)

Worth the price for amplifier.

Pros: Can install underneath driver's seat.

Cons: None

Great amp

Written by: Kristoffer from Provo, Utah on September 8, 2013

What a great amp! First amp I've personally boughten and I've been very pleased so far! Had it for almost a year now. Love how small it is and easy to hook up. I have mine mounted to the back of my seat and it looks great! Definitely recommend!

Pros: Small Plenty of power Easy to install

Cons:

Great Amplifier, Easy Install

Written by: DPowell from Harrisburg, Pennsylvania on September 7, 2013

This is a great amplifier. I used this and underrated my speakers that were able to handle 100W rms a piece. Let me tell you what, 75W a channel is perfect. Plenty of power going to my speakers, no distortion at all. Plus the high pass filters are real convenient when paired with a pair of subwoofers. Great amplifier. Crutchfield is definitely the quickest supplier you'll find, but unfortunately not the cheapest.

Pros: Easy installation All the inputs(positive and negative, power, ground, etc) are all nicely separated. Lots of power And of course, its Rockford Fosgate quality.

Cons: None that I can think of.

Great Amp, Small Size

Written by: Anonymous from Mentor, OH on April 22, 2013

Purchased this amp to simplify my system in newer car, i.e. going from two amp system to one 4 channel amp. Installed along with new JVC KD-X80BT head unit, driving JBL GTO938 in rear and old Infinity reference components in the front. This amp has plenty of power. Besides breathing new life into the old Infinities, provides ample power to provide me with all the base I need from the JBLs. The small size allowed me to install under rear deck. Love the various controls and set screws for wiring.

Pros: Great Amp

Cons: None

Great Amp

Written by: Steveintexas from NE Texas on October 21, 2012

Crutchfield Customer Review (What's this?)

Installed the R400-4D in a 2009 F150 along with 4 Kenwood KFC-680C speakers. Also replaced the headunit with a Pioneer AVH 8400H receiver. The amp was easy to install and sounds great. 100% improvement over the factory radio. I've always liked the Rockford Fosgate products.

Pros: Small footprint Easy install

Cons: Should have done this sooner.

Great amp

Written by: Marvin from CA on June 27, 2012

Great amp ive used rockford amps since the 90s and absolutely love them especially with their new style amps that have no more external fuses...

Pros: Does the trick plenty of power with a small footprint

Cons: None

Details

Hands-on research

What's in the box?

Download the Rockford Fosgate Prime R400-4D manual

  • 4-Channel amplifier
  • 3mm Hex key
  • Installation & Operation Manual
  • Amplifier Verification Certificate
  • 4 Self-tapping screws (length=1-5/8")

Product Research

Features
Controls
Connections

Features

Overview: The Rockford Fosgate Prime R400-4D is a 4-channel full-range Class D amplifier. It is optimized to power a full-range front/rear speaker system. You can also bridge the front and/or rear channels to run a subwoofer or two. The Class D design is very efficient with a cast aluminum heatsink to keep it in a small footprint.

CEA 2006 Compliant: The R400-4D's power ratings are measured according to the strict standards dictated by the Consumer Electronics Association (CEA). These standards allow you to accurately compare the rated power output of all CEA 2006-compliant amplifiers, even different brands. Manufacturers who adhere to the standards can display the CEA 2006 logo on their products and packaging. The RMS power output is as follows (measured with a 14.4 volt input, <1% THD+N, 20 Hz-20 kHz):

  • 4-Ohm: 75 watts x 4
  • 2-Ohm: 100 watts x 4
  • Bridged (4-Ohm): 200 watts x 2

LED Indicator: The amplifier is equipped with a top-mounted LED indicator which illuminates blue when the unit is turned on. The LED illuminates red when a protection circuit engages (short circuit or too low an impedance is detected at the speaker connections). The amplifier automatically turns off if this occurs.

Mounting: The amplifier can be mounted vertically, horizontally, or inverted using the supplied mounting screws; horizontal mounting (right side up) will provide the best cooling.

Controls

Independent Controls: The R400-4D has independent, top-mounted controls for the front and rear channels. The controls include:

  • Gain Control: The amplifier has rotary gain controls (0 to 11) for front and rear channels.
  • Crossovers: The amplifier features independent Butterworth crossovers for the front and rear channels. Each crossover can be set for low-pass, high pass, or all-pass (full range). The crossover frequency is continuously variable from 50-250 Hz with a slope of 12 dB per octave.

Punch EQ: The rear channel has an independent Punch EQ (bass boost) control that works with the crossover switch. When the rear channel crossover is set to low-pass, the Punch EQ can add a bass boost, centered at 45 Hz, from 0 dB to +18 dB.

2/4 CH Switch: When the 2/4 CH switch is set to the 2 CH position, the inputs are switched to a 2-channel mode. The signal on the front input feeds all four output channels, however, you lose front to rear fading capability. In the 4 CH position, the amp uses both front and rear inputs and fading capability is restored.

Connections

Power Terminals: The power and ground terminals are nickel-plated set-screw terminals, and will accommodate up to 4-gauge wire. The set screws can be tightened/loosened with the supplied 3mm hex key.

Fuses: The amplifier does not have on-board fuses. A 40A fuse should be placed on the power wire within 18" of the battery.

Remote Turn-On Terminal: The remote turn-on terminal is a nickel-plated set-screw terminal that will accommodate up to 8-gauge wire. The set screws can be tightened/loosened with the supplied 3mm hex key.

Speaker Terminals: The speaker terminals are nickel-plated set-screw terminals that will accommodate up to 8-gauge wire. The set screws can be tightened/loosened with the supplied 3mm hex key.

RCA Input Jacks: There are two pairs of RCA input jacks for the front and rear channels. They are nickel-plated to resist signal degradation caused by corrosion.

RCA Pass-Thru Jacks: The nickel-plated RCA pass-thru jack provides a convenient source for daisy-chaining an additional amplifier without running an extra set of RCA cables from the front of the vehicle to the amplifier location.

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.

Accessories
Q & A

Customer Q&A

Crutchfield asked  
Why did you buy this?

I am using everything Rockford fosgate I need 2 twleves a amp and a box combo [ daniel  Dec 17, 2015 ]
Is it what i need [ sergio  Dec 11, 2015 ]
Bang for the buck [ Brent  Dec 05, 2015 ]

2 questions already asked

U won't go wrong with RF amps. I use the prime series. They put out gobs of power!! Plus They're small and don't draw much current. I didn't use a capacitor and I have no problems with lights dimming or bass cutting out and I'm running the R500x1D at 2 ohms. U won't find a better amp for the price imo. [ william  Jan 07, 2016 ]
Rockford fosgate is the only option in my opinion, I have never had issues with my amps and when it comes to getting the power from theses amps it s way to easy . Well know and depndable quality unsurpassed . Don't make a mistake and choose a cheaper brand because you won't be happy , to with the best and forget about the rest. Dave [ David  Jan 06, 2016 ]
Thanks for your question. For information on selecting the best amp for your speakers and sub I would recommend reaching out to an Advisor by phone (1-800-324-9695) or online chat. They will be able to help determine the differences between the amp models and help you make the best choice for your system. [ Kenny  Jan 06, 2016 ]  Staff
If you purchased the product from Crutchfield, feel free to contact our Tech Support team. They can walk you through the settings on the product and see if there may be a fix. Our toll-free Tech Support number is printed on your invoice, and is also available under the "My Orders" tab in the "My Account" section of our website. If you did not purchase the unit from Crutchfield, then you may want to contact the manufacturer. You can also post your question in our forums: http://community.crutchfield.com. Or try our online support center: http://crutchfield.custhelp.com/app/answers/list/kw/. [ Krissy  May 26, 2014 ]  Staff
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