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Rockford Fosgate R300X4

300W 4-Channel Class AB Prime Series Amplifier

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List price $239.99

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25% off a 8 Gauge Amp Kit with Purchase

Save 25% off the Belva BAK82 install kit, the perfect kit for this amp.

5.50

67753

438

Rockford Fosgate R300X4

$129.99

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25% OFF

Belva BAK82

$21.99

Special Price $16.49 ($21.99 if purchased separately)

Belva BAK82

• Complete 8 Gauge 2-Channel Amplifier Installation Kit
• Designed Specifically For Car Audio Systems Up to 500 Watts RMS
• Premium Power and Ground Wire Provides Optimal Power Transfer
• Mini-ANL Fuse Holder With A 60 Amp Mini-ANL fuse
• 30% Copper CCA Wire

(Offer 1 of 1)

Combined Total Price

$146.48

You Save $5.50

The PRIME Choice

Rockford Fosgate amplification at an unbelievable value. The R300X4 4-channel amplifier is so versatile, it will be the only amplifier your system needs. Full-range or component speakers on the front channels and a single R1S410 10" or R1S412 12" woofer bridged/mono on the rear. Consider your system clean, loud and done!

Class-AB

An amplifier topology with the best of both worlds; a Class A preamp and Class B output stage. Class A topologies area great for sound quality but can require alot of current. Class B designs are great for power delivery. Amplifier designs utilizing a Class A/B topology reaps the benefit of great sound quality in the front-end (preamplifier stage) while delivering great power in the output stages (MOSFET drivers).

General Features:
  • Prime Series Full Range Class AB 4-Channel Car Amplifier
  • RMS Power Rating:
    • 4 ohms: 50 watts x 4 chan.
    • 2 ohms: 75 watts x 4 chan.
    • Bridged, 4 ohms: 150 watts x 2 chan.
  • MOSFET power supply
  • LED power (green) and protect (red) indicators
  • Variable Bass Boost (0 to +12 dB bass boost at 45 Hz)
  • Soft Start Turn-on
  • 4/2 channel switch
  • 50 Amp In-line fuse is highly recommended
  • Heavy duty cast aluminum alloy heatsink for extreme heat dissipation
  • Variable high-pass filter (50-250 Hz, Butterworth 12 dB/octave)
  • Variable low-pass filter (50-250 Hz, Butterworth 12 dB/octave)
  • CEA-2006 compliant amplifier
  • Dimensions: 13-1/4"L x 6-3/4"W x 2"H
  • 8-gauge power and ground wiring is required for installation. Contact us for information regarding a discount on select amplifier kits when purchased together with this amplifier.
  • 1-year SonicElectronix.com warranty

Product History:

Rockford Fosgate R300X4 thumbnail
(newest, current model)
Rockford Fosgate R300-4 thumbnail
(previous model, replaced by Rockford Fosgate R300X4)

Power Specifications - Full Range Channels

RMS Power @ 4 ohms

The RMS power rating is the measure of continuous power that an amplifier can output, or a speaker can handle. It is the most accurate depiction of real, continuous power that the industry has so far.

If the final impedance of your speakers or subwoofers equals 4 ohms, this is how much power this amplifier will supply at that ohm level. The higher the RMS wattage, the more clean and loud your music will sound.

50 watts x 4 channels
RMS Power @ 2 ohms

The RMS power rating is the measure of continuous power that an amplifier can output, or a speaker can handle. It is the most accurate depiction of real, continuous power that the industry has so far.

If the final impedance of your speakers or subwoofers equals 2 ohms, this is how much power this amplifier will supply at that ohm level. The higher the RMS wattage, the more clean and loud your music will sound.

75 watts x 4 channels
Bridged RMS Power

Bridging refers to combining two channels on an amplifier to create one channel with double the voltage and an increased power output. A 2-channel amplifier will bridge down to 1-channel and a 4-channel amplifier can bridge to create 2-channels. An amplifier is most commonly bridged to drive a subwoofer.

Remember, once you bridge two channels down to one its final impedance will be 4 ohms unless otherwise specified. This rating lists the RMS power created once an amplifier is bridged.

150 watts x 2 channels

Amplifier Specifications

Amplifier Series
This designates the series of the amplifier. Many amps are available in a litany of different wattage and channel configurations, but maintain consistent features throughout the product line.
Prime (Rockford Fosgate)
Amplifier Class

An amplifier increases the power of the signal being fed to it by taking energy from its power supply and matching the signal but increasing its amplitude. Amplifiers use many different methods for converting these electrical signals and have been categorized into classes.

Class A/B: Greater than 50% of the input signal is amplified while the other percentage is “off”. These amplifiers have a small amount of current flowing through the output transistors all the time which almost eliminates crossover distortion. Class A/B has great sound quality but is not as efficient as class D. These amps are most commonly used to drive speakers.

Class D: Also known as switching amplifiers, class D amps have output transistors that are completely turned “on” or “off”. This means that when the transistors are on, there is almost no voltage across them but when they are off there is significant voltage but no current flowing through it which makes these amplifiers very efficient at the cost of sound quality. These amps are most commonly used to drive subwoofers.

Other Classes: You may see classes such as GH, bD, X, FD, etc. by some manufactures. These amplifiers tend to be either class A/B, D or a hybrid of the two but with improvements to their designs that can make them more efficient or offer better sound quality.

AB
Number of Channels
Each channel on an amplifier will power one speaker using a positive and negative cable. There are various types of amplifiers, each designed to power a certain number of speakers. Monoblock amplifiers, also known as single channel, are designed to power one or more subwoofers. These amplifiers often have very high power ratings. On the other hand, multi-channel amplifiers power multiple speakers, usually at lower power ratings. 2-Channel and 4-Channel amplifiers can power car speakers or low powered subwoofers. Occasionally you might see a 5 or 6-channel amplifier that can power speakers and subwoofers at the same time. The most common setup is a monoblock amp to run subwoofers and a 4-channel amp to run door speakers. Check out our Knowledge Base for more information.
4
Total RMS Power Output
Total RMS power is measured by multiplying RMS power per channel by the number of channels, and is calculated at the lowest level of operating impedance.

RMS power is the amount of continuous power, measured in watts, that an amplifier produces is called RMS power. The higher the RMS figure, the louder and cleaner your music sounds.

The RMS output figure is much more accurate than the peak rating when comparing products.

300 watts
Maximum Input Gauge Size
This is the largest gauge wire that will fit into the power and ground terminals of this device. The lower the gauge number, the thicker the wire is. For example, a 4 gauge wire is thicker than an 8 gauge wire and thus has higher current carrying capacity. Always do your best to get this size wire to reduce the risk of damage to your components.
8 AWG
Minimum Impedance Unbridged
The lowest impedance the amplifier will handle when it is not bridged.
2 ohms
Minimum Impedance Bridged
The lowest impedance the amplifier will handle when it is bridged.
4 ohms
THD at Rated RMS Power
The amount of change in harmonic content of the signal as it is amplified. A lower figure indicates less change and a more accurate amp. THD below 0.10% is inaudible.
1.0%
Speaker Level Inputs
Speaker level inputs are commonly referred to as high-level inputs and vice versa. This input type allows you to get your audio signal directly from the speaker wire in your vehicle, instead of using RCA cables. The advantage of this is factory integration, as most stock radios do not have RCA outputs to run amplifiers.
Yes
Preamp Outputs
Many amplifiers are equipped with RCA preamp outputs which pass the original music signal from the source to additional amplifiers. This is known as daisy chaining because the source connects to the first amp, and the first amp connects to the second amp, etc. The advantage to daisy chaining is you only need one 2-channel RCA cable to transfer the signal from the head-unit to the amplifier, and then one additional cable for each amp being daisy chained.
1 pair
Built-in Crossover

A crossover is a type of filtering system that permits only certain frequencies to play. A Low-Pass (LP) crossover allows only frequencies below its setting to get through which is good in the case of some subwoofers. A High-Pass(HP) filter allows frequencies above its setting to pass through, this is normally used on speakers.

When a crossover is set to FULL it means no filtering is added and the full frequency spectrum is allowed through the amplifier. Filtering is important because feeding a speaker frequencies it cannot reproduce effectively creates distortion.

Low-pass (LP)
High-pass (HP)
High-Pass Crossover Frequency
The high-pass crossover frequency can be a fixed crossover point or a variable crossover range. A variable high-pass crossover allows you to select a specific crossover point which allows frequencies above the set crossover point to pass, while making frequencies below the set point gently or harshly roll-off, depending on the steepness of the slope.

The steepness of the roll-off slope is measured in dB/octave and refers to the rate of attenuation (lowering of volume) outside their pass bands.

50 - 250 Hz
Low-Pass Crossover Frequency
The low-pass crossover frequency is typically used for subwoofers. It can be a fixed crossover point or a variable crossover range. A variable low-pass crossover allows you to select a specific crossover point which allows frequencies below the set crossover point to pass, while making frequencies above the set point gently or harshly roll-off, depending on the steepness of the slope.

The steepness of the roll-off slope is measured in dB/octave and refers to the rate of attenuation (lowering of volume) outside their pass bands.

50 - 250 Hz
Signal-to-Noise Ratio
This spec compares the strength of the signal to the level of background noise. A higher value indicates less background noise.
100 dB
Channel Separation
Also referred to as crosstalk. The amount of interference on one stereo channel caused by the leaking of the other stereo channel. The higher the rating in decibels (dB), the better the Channel Separation.
50 dB
Bass Boost
The objective of the bass boost is to get more kick out of your subwoofer. It is a circuit that emphasizes the lower frequencies at a given point. The bass boost should always be set first before setting the gain. This feature is known for destroying subwoofers and is commonly used incorrectly, so be cautious.
Selectable 0/+6dB/+12dB
Bass/Gain Remote
If the amp comes with a bass/gain remote you will be able to control the level of your bass from your dashboard. Typically bass remotes also include a 16-20 ft. wire for installation.
Optional (Accessory required and sold separately)
Fan Cooled
A great feature to have if an amp generates a large amount of heat. Cooling fans can help regulate the temperature to prevent the amp from overheating (burning).
No
Strappable
Some amplifiers can be "strapped" together in order to increase the output of a single audio channel. These amplifiers feature RCA preamp outputs, allowing you to pass the signal directly from one amp to the other to ensure consistency.
No
CEA-2006 Compliant
Amplifiers that have been tested to meet specific standards. When a car amplifier meets these standards, you can be sure that it will be able to produce the amount of power specified by the official CEA-2006 rating. Usually, these rating consist of the following items:
  • RMS Power
  • Signal-to-Noise Ratio

This rating applies to both external car amplifiers, as well as the amplifiers inside of in-dash stereos.

No
Sonic Certified Amplifier
Sonic Certified amplifiers have been tested by the experts at Sonic Electronix to meet or exceed the wattage ratings provided by the manufacturer. If this is marked as Yes, then you can trust the wattage ratings. If marked as No, then we have tested the amplifier and it did not meet the advertised wattage ratings. If marked as Not Tested, then the Sonic Electronix experts have not yet been able to test the amp.

Specials with this Item

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Warranty and Return Policy

Parts Warranty Duration
1 year
Labor Warranty Duration
1 year
Warranty Provider
Sonic Electronix

Summary of Customer Ratings & Reviews

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Browse 2 questions and 3 answers
Hide answersShow all answers | Sort by
Does this amp require being placed in the open for cooling or could it be placed in a compartment with little to no air flow? Thanks.
Gary D on Sep 6, 2014
Best Answer: Hello Gary,

Most amps, Especially Class AB, must have some kind of ventilation. No manufacture will ever disclose that Lack of air flow is ok. Keep in mind, their products travel the world, and no two environments are alike. In the case of the R300X4 - as already described by our awesome customer Shawn - it will get fairly up in temperature. Obviously this will also depend on CCA vs OFC Power/Ground, Outside Elements, Install Location, etc... Nevertheless, we do note suggest any 'no air flow compartment'.
Reply · Report · Customer SStaff on Sep 8, 2014
· Add Answer · I Have This Question Too (0)
does this have settings where i can have 2 channels running lower power and the other 2 higher power? i have 4x6s in the doors and 6x9s so i was hoping to max the 6x9s at 50 watts and have the 4x6s at like 30 watts can i do that with this amp?
matthup on Nov 9, 2014
· Add Answer · I Have This Question Too (0)

Product Summary

Manufacturer

Model Number

R300X4

UPC

780687340582

Weight

7.50lbs

Internal SKU

r300x4

Internal Product ID

67753

Sonic Electronix Wiring Guide

Wiring Diagram Legend

Warning: The image depicted shows the resistance change when wiring multiple subwoofer terminals. Please refer to your subwoofer's owner's manual for the proper wiring of its terminals. Sonic Electronix, Inc. is not responsible for damage caused to your audio system or vehicle due to improper installation. Please call tech support at 1-877-289-7664 if you require additional assistance.

Product Name: Rockford Fosgate R300X4

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