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Rockford Fosgate Prime R300-4

4-channel car amplifier — 50 watts RMS x 4

10 Reviews

Item # 575R3004

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Our take on the Rockford Fosgate Prime R300-4

Now you can get Rockford Fosgate performance at value prices. Prime Series amplifiers bring out your music's subtle details as they drive your speakers with the clean power you need to overcome road noise and fill your car with sound.

Now you can get Rockford Fosgate performance at value prices. Prime Series amplifiers bring out your music's subtle details as they drive your speakers with the clean power you need to overcome road noise and fill your car with sound.

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. Your driver's seat will become your favorite place for listening when you add the clarity and impact of a Rockford Fosgate amp.

The R300-4 4-channel amp puts out 50 watts RMS per channel to your speaker system, or you can bridge it to supply 150 watts RMS to a pair of speakers or subs in 2-channel mode. High- and low-pass filters and Rockford Fosgate's famous Punch bass boost let you tune your speakers for maximum performance.

Product Highlights:

  • 4-channel car amplifier
  • 50 watts RMS x 4 at 4 ohms (75 watts RMS x 4 at 2 ohms)
  • 150 watts RMS x 2 bridged output at 4 ohms (4-ohm stable in bridged mode)
  • CEA-2006 compliant
  • high-pass filter (80 Hz, 12 dB/octave)
  • variable low-pass filter (50-250 Hz, 12 dB/octave)
  • selectable bass boost (0, 6, 12 dB at 45 Hz)
  • Class-AB amplifier design
  • MOSFET power and output stages
  • frequency response: 20-20K Hz
  • two sets of preamp inputs
  • 8-gauge power and ground leads recommended — wiring and hardware not included with amplifier
  • fuse rating: 25A x 2
  • 7-3/4"W x 2-1/2"H x 17-13/16"D
  • warranty: 1 year
  • Our 60-day money-back guarantee

What's in the Box:

  • Four-channel amplifier with two 25-amp fuses installed in chassis
  • 2 Additional 25-amp fuses
  • 4 Mounting screws
  • 4 Flat washers
  • Installation/Operation Manual (Eng/Spa/Fre)
  • Amplifier Verification Certificate

Installed in my 60 VW bus to drive 6x9's and 6.5's... Works great.... Sounds Great...

C-Rad, Sacramento, Ca


Rockford Fosgate Prime R300-4 Reviews

Average Customer Review(s):

(10 Reviews)

Great so far

C-Rad from Sacramento, Ca on 8/9/2013

Installed in my 60 VW bus to drive 6x9's and 6.5's... Works great.... Sounds Great...

Pros: easy to install and set up

Cons: big amp for limited spaces...

Great Amp for the money!

Brad D. from Raymore, MO. on 7/12/2013

Crutchfield Customer Review (What's this?)

it's a little big and having to adjust gain and what not on the side was an issue, almost.. I like my RF mono, it has adjustments on top and seems to make things easy. Over all it sounds great to my ears, first "self" installed amp, along with my mono, and Crutchfield made it simple. Looked up my specific vehicles speaker wiring diagram and it was simple! One note. My Head unit only has 2 pre amp outs so I had to share my rear speakers with the front, easier for my needs. The Y's they sold me were fine but if you put the rca cables too close I got a hum with the vehicle on. Seperated the Y's and good to go! Very easy to adjust and very happy!

Pros: Sound and price

Cons: big and bulky, wish it had adjustments on top of amp

After 18 months

nick from ohio on 8/16/2012

Great amp as far as sound quality. Had it pushing a set of components and a set of 6x9s. But after 18 months the rear channel is dead. It replaced a alpine 4 channel. i will just put the alpine back in. After 4 years the alpine still worked flawless.

Pros: Great sound

Cons: Short life span

Rockford Fosgate Prime R300-4

MichaelW from Gainesville, FL on 11/22/2010

Crutchfield Customer Review (What's this?)

If there is anything more sonically beautiful than a Rockford Fosgate amp in car audio I've never come across it. This is an unbelievable amp for the price. If you're familiar with RF, you won't be disappointed in this amp. If you aren't, this is a great product with which to get acquainted with them.



Just plain great!

Eric from San Mateo, CA on 9/25/2009

Crutchfield Customer Review (What's this?)

Finally got this all wired up in my Chevy Astro van. It powers the four rear speakers. 6x9's and 5x7s. They now sound the way they should. I can crank it up and the sound remains crisp and clear. Only issue was finding a good place to install it, but once you have that, its a piece of cake. Relatively. After all the interior panel removal... Coupled with the cabling kit, this was a simple installation, giving excellent results.




Anonymous from NC on 6/30/2009

Crutchfield Customer Review (What's this?)

I'm running a pair of Infinity 6020 CS speakers up front plus a pair of Pioneer 6x9s in the rear deck off this amp. Head unit is Kenwood hd942U. This amp delivers plenty of power for my needs and sounds great. It doesn't heat up at all, I have it mounted in the trunk and it performs fine even on 95+ degree days. The amp is a bit long, probably would not be a good choice for mounting under a front seat if you want it hidden. A very good amp for a decent price.




speedy from south boston ,va on 6/6/2009

Crutchfield Customer Review (What's this?)

great power and alternator noise...just a lil bit long..but smaller than older units of same comparison.



Great Amp

5897 from Oregon on 4/30/2009

Using it to power a 150watt prime 10" with the bridge mode. Sounds great, is easy to control, punch bass adds a ton of kick. Doesn't get hot so can be mounted anywhere. Great budget amp



Rockford Fosgate Prime R300-4

Nimz from Arcadia, LA on 4/28/2009

Crutchfield Customer Review (What's this?)

This is my 2nd Rockford Fosgate amplifier I've owned. The R300-4 mounted flawlessly to the rear truck panel like a glove. This is handling 2 Infinity Reference 6020cs up front and 2 Pioneer TS-A1782R in the extended cab doors with no problem at all. Definitely a superb amp. Amp also has a nifty LED that shines blue when functioning properly and red when something is wrong, haven't seen the red yet though!



It's Prime time

Robert from San Diego, Ca. on 4/4/2009

Rockford Fosgate has done it again. I own a 2002 Ford F150 Supercrew. The Prime R300-4 is a excellent amp for my four 5x7 Polk Audio db 571s in the doors. Smooth output and good power. Don't think 50w-4 per channel. How about 63w-4 per channel and even more if you want to bridge front to back fader. The Rockford Fosgate Prime has replaced the Punch and is a good amp for the price. You don't need big numbers to make big sound. Just the right product, Rockford Fosgate "Prime."




Hands-on research

Product Research



Overview: The Rockford Fosgate R300-4 Prime 300 watt 4-channel amplifier is designed to power a set of full-range or component speakers in 4-channel mode, two subwoofers in bridged 2-channel mode, or two full-range speakers and a single subwoofer in tri-way mode.

CEA 2006 Compliant: The Rockford Fosgate R300-4 Prime'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 if they come from different brands. Manufacturers who adhere to the standards can display the CEA 2006 logo on their products and packaging.

  • 4-Channel (4-Ohm): 50 watts RMS x 4-channel in 4-ohms @ 20-20,000Hz with 1% THD
  • 4-Channel (2-Ohm): 75 watts RMS x 4-channel in 2-ohms @ 20-20,000Hz with 1% THD
  • 2-Channel Bridged (4-Ohm): 150 watts RMS x 2-channel in 4-ohms @ 20-20,000Hz with 1% THD
  • Tri-Way Mode: 50 watts RMS x 2-channel in 4-ohms @ 20-20,000Hz with 1% THD + 150 watts RMS x 1-channel in 4-ohms @ 20-20,000Hz with 1% THD

MOSFET Power: The Rockford R300-4 is equipped with a MOSFET power supply and output stage for good sound, efficiency and dependability.

LED Indicators: The Rockford Fosgate amplifier is equipped with two side-mounted LED indicators:

  • Power LED: This LED illuminates green when the unit is turned on.
  • Protect LED: This LED illuminates red if a short circuit or too low an impedance is detected at the speaker connections. The amplifier will automatically shut down if this occurs.

Mounting: The amplifier can be mounted vertically or horizontally using the supplied mounting screws. The amplifier should never be mounted upside down or in an engine compartment (this will void your warranty).


Gain Control: The amplifier's gain control is preset to match the output of most source units. The gain control can be adjusted from 150mV to 8V.

Crossovers: The amplifier features an independent Crossover Switch for the front and rear channels which allow you to select Full-Range, High-Pass, or Low-Pass:

  • Full-Range: The full-range setting allows all frequencies (20-20kHz) to pass through the amplifier from your connected headunit to your connected speakers.
  • High-Pass: The high-pass setting is fixed and allows only frequencies above 80Hz to pass through the amplifier to your speakers.
  • Low-Pass: The low-pass setting is variable and allows only frequencies below 50-250Hz to pass through the amplifier to your speakers.

Punch Bass: The amplifier features an independent Punch Bass (Bass Boost) for the front and rear channels. The Punch Bass can be set to 0, 6, or 12dB at a fixed 45Hz.


Power Terminals: The power and ground terminals are nickel-plated screw terminals and will accommodate up to 4 AWG power/ground wire (up to 1/2" spade or ring-style connector).

Remote Turn-On Terminal: The remote turn-on terminal is a nickel-plated screw terminal that will accommodate up to an 8 AWG wire (up 3/8" spade or ring-style connector). This terminal is used to remotely turn-on and turn-off the amplifier when +12V DC is applied, when connected to your headunit's remote turn-on lead.

Speaker Terminals: The eight speaker terminals (left +/- and right +/-) are heavy duty, nickel-plated screw-terminals what will accommodate up to 8 AWG speaker wire (up to 3/8" spade or ring-style connectors).

RCA Input Jacks: The industry standard RCA jacks (2-pair) provide an easy connection for signal level input. They are nickel-plated to resist signal degradation caused by corrosion.

Fuse: The amplifier is equipped with two installed 25-amp ATO fuses. The amplifier also comes supplied with two spare 25-amp fuses.

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.