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Rockford Fosgate Punch 501X

65W x 4 Car Amplifier

Item # 575501X

The Rockford Fosgate Punch 501X slams your speakers with a one-two combination, so they deliver the...

Find what Fits your car

The Rockford Fosgate Punch 501X slams your speakers with a one-two combination, so they deliver the...

Discontinued item

Item # 575501X

About the Rockford Fosgate Punch 501X

The Rockford Fosgate Punch 501X slams your speakers with a one-two combination, so they deliver the uncompromising musical performance you demand.

The Rockford Fosgate Punch 501X slams your speakers with a one-two combination, so they deliver the uncompromising musical performance you demand.

Part one: power. The clean circuit design, MOSFET output stages, and proprietary technology inside the 501X bring out extraordinary detail in your music. You'll hear clarity and strength you just can't get from an in-dash receiver — or a lesser amp. Power four full-range or component speakers with 65 watts RMS per channel; or switch the amp over to bridged mode — you'll get 250 watts x 2 channels (ideal for a pair of 4-ohm subwoofers)!

Part two: control. Rockford Fosgate includes switchable high- and low-pass crossovers, so you can tweak the frequencies you send to your speakers, making the amp suitable for a variety of tasks.


  • 65 watts RMS x 4 at 4 ohms
  • 125 watts RMS x 4 at 2 ohms
  • 250 watts RMS x 2 at 4 ohms in bridged mode
  • 2-, 3-, or 4-channel output
  • 4-ohm stable in bridged mode
  • Tri-way capable (Tri-Way crossover required)
  • requires 8-gauge power and ground leads — wiring and hardware not included with amplifier
  • front and rear switchable high-pass (120 Hz, 12 dB/octave) and low-pass (80 Hz, 12 dB/octave) crossovers
  • MOSFET power supply and output devices
  • Maximum Efficiency Heat Sink Application (MEHSA) mounting technology increases the heat transfer from the MOSFET output devices to the heat sink, for higher power output, lower operating temperatures, and greater reliability
  • TOPAZ — noise-killing differential inputs that eliminate 80% of ground loop noise
  • Trans•ana circuitry keeps preamp voltages low and signal paths simple for outstanding audio quality
  • NOMAD — advanced protection circuitry for "intelligent" shutdown protection
  • speaker- and preamp-level inputs
  • preamp outputs
  • 12-1/16"W x 2-3/8"H x 9-7/8"D
  • 1-year warranty

What's in the box:

  • 4-Channel amplifier
  • 2 End caps (attached to amplifier)
  • Four 3/4" self-tapping screws
  • One 1/8" Allen wrench
  • One 7/64" Allen wrench
  • One 3/32" Allen wrench
  • One 3/32" set screw (extra)
  • One 1/8" set screw (extra)
  • Two 8" speaker-level input harnesses
  • 1 In-line fuse holder
  • One 50-amp AGU fuse
  • 1 Female quick-slide
  • Installation and Operation manual
  • Punch Verification Certificate
  • "Team RF" sticker
MFR #501X

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More details on the Rockford Fosgate Punch 501X

Mark G.

Product Research

Inputs and Outputs Notes
Manual Correction


Cast Aluminum Heatsink: The cast aluminum heatsink dissipates heat generated by the amplifier's circuitry. The inherent advantage of casting provides a 30% improvement of cooling over conventional extrusion heatsink designs.

Trans-ANA (TRANSconductance Active Nodal Amplifier): The trans-ANA is a circuit that allows the audio signal to pass through the amplifier at low voltage. The signal is directly level-shifted to the fixed high voltage rails via a pair of drive transistors. Signal linearity is assured by an active node formed  by the drive transistors at ultrasonic frequencies. The result is crystal clear sound quality.

MEHSA (Maximum Efficiency Heat Sink Application): MEHSA is a Rockford Fosgate proprietary process that increases the heat transfer from the MOSFET devices to the heatsink. The multi-layer insulated metal MEHSA substrate operates with minimal thermal resistance, spreading heat both downward and outward to quickly dissipate heat from each device across the heatsink. This allows greater power output, enhanced thermal stability, and maximum reliability.

TOPAZ (Tracking Operation Pre-Amplifier Zone): TOPAZ is a circuit that simply eliminates noise. The TOPAZ circuit allows the amplifier ground to move with the source unit ground, creating a "noise elimination" zone just before the preamp section. If there is any noise in the ground coming down the RCA line to the amplifier, TOPAZ amazingly tracks it down and eliminates it. The result is a 30-40dB improvement of the isolation between input ground and chassis ground. 

NOMAD (NOn-Multiplying Advanced Decision): NOMAD is an intelligent protection circuit that uses an analog computer to make real time decisions regarding temperature, voltage, current and impedance. The unit is protected without limiting sound output unless needed.

DSM (Discrete Surface Mount): In the manufacturing process high speed robotics are used to place 0% tolerance resistors and large board traces providing greater reliability and efficiency.

INDIGO (INDexed Ideal Gain Operation): INDIGO is a circuit that maximizes the output power of the amplifier by making better use of the power supplied by the car. As the battery voltage drops, INDIGO tightens up so the amplifier delivers the rated power, resulting in more consistent power coming from the amp.

In-line Fuse: This amplifier does not have a built-in protection fuse, but comes with a separate in-line AGU fuse holder and 50-amp AGU fuse. The power wire must be fused within 18" of the vehicle's battery.

Note: Most amplifier wiring kits will include an in-line fuse holder.

Internal Crossovers: The front and rear channels have independent crossovers. Each crossover is a 12dB/octave Butterworth filter selectable for 120Hz high-pass, all-pass (full range), or 80Hz low-pass operation. 

RCA Pass-Thru Jacks: The pass-thru jacks provide 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. The pass-thru jacks output a full-range signal.

Power LED: The LED power indicator is located under the RF Power center badge on top of the amplifier. The center badge illuminates when power is supplied to the amp.

Inputs and Outputs Notes

Left Side of Amplifier:

  • B+ (Battery Power): set screw terminal that will accept up to 8-gauge power wire
  • GND (Ground): set screw terminal that will accept up to 8-gauge ground wire
  • Speaker Outputs: 4 pairs of set screw terminals that will accept up to 8-gauge speaker wire
  • REM (Remote Turn-on): 0.250" male quick-slide for remote turn-on lead (a female quick-slide is supplied)

Manual Correction

Crossover Slope: The manual incorrectly lists the slope for the internal crossovers as 24dB/octave. The internal crossovers actually have a slope of 12dB/octave.

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