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Rockford Fosgate TM400X4AD Power Series marine/powersports 4-channel amplifier — 100 watts RMS x 4

Item # 575TM400X4

Rockford Fosgate designed their Power Series TM400X4ad 4-channel amplifier for marine and powersports applications.

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Rockford Fosgate designed their Power Series TM400X4ad 4-channel amplifier for marine and powersports applications.

10 questions - 17 answers

Item # 575TM400X4

In stock
$569.99 Sale: -$220.00 off

About the Rockford Fosgate TM400X4AD

Jon Paul

Ready to rock your boat

Rockford Fosgate designed their Power Series TM400X4ad 4-channel amplifier for marine and powersports applications. You can power systems with front and rear speakers, drive a pair of subs, or switch the amp to 3-channel mode to power a system with a set of speakers and a subwoofer.

Ready to rock your boat

Rockford Fosgate designed their Power Series TM400X4ad 4-channel amplifier for marine and powersports applications. You can power systems with front and rear speakers, drive a pair of subs, or switch the amp to 3-channel mode to power a system with a set of speakers and a subwoofer.

Rockford Fosgate's proprietary Class AD technology allows this compact amp to draw big power with less current draw from your electrical system, while the Constant Power feature keeps power consistent with varying impedances. High- and low-pass filters tailor the amp to the job at hand, whether it's powering a nice set of component speakers or a couple of marine subs. This amp will provide outstanding power and versatility in a variety of vehicles on land and sea.

Made to handle moisture and heat

It's built to stand up to outdoor life, too, with conformal-coated circuitry that withstands moisture and dirt and stainless steel hardware that won't succumb to corrosion. With a 3-stage thermal lock extrusion, dual- fan forced induction system, and real-time thermal monitoring, the TM400X4AD can rock hard without overheating – even when it's tucked into a tight space.

Level setting made easy

The TM400X4ad uses Rockford Fosgate's CLEAN level setting technology, so there's no more guesswork while setting your gain levels. Easy-to-see LED indicators identify clipping so you can set your amp up for maximum performance while eliminating distortion.


Product highlights:

  • 4-channel marine/powersports amplifier
  • 100 watts RMS x 4 at 4 ohms (400 watts peak)
  • 100 watts RMS x 4 at 2 ohms
  • 200 watts RMS x 2 at 4 ohms (bridged)
  • CEA-2006 compliant
  • Class AD amp technology
  • 4-ohm/2-ohm multi-impedance constant power
  • conformal-coated circuit board — suitable for power sports and marine applications
  • marine-grade stainless steel hardware
  • twin cooling fans and real-time thermal sensing
  • hidden top-mount control panel
  • CLEAN set-up technology with LED input/output indicators
  • speaker-level inputs
  • variable low- and high-pass filters (50-250 Hz at 12 dB/octave)
  • tone controls: 0-18 dB at 45 Hz; 0-14 dB at 12,000 Hz
  • frequency response: 20-20,000 Hz
  • fuse rating: 60A x 1 (fuse not included)
  • dimensions: 8-5/8"D x 1-11/16"H x 4-5/16"W
  • requires 8-gauge power and ground cable
  • warranty: 2 years
  • MFR # TM400X4AD

What's in the box:

  • 4-Channel moto-marine amplifier
  • Power/ground/turn-on plug (installed)
  • Two 8" Speaker output harnesses (bare wire to 4-pin Molex)
  • Two 14" Input harnesses (2 RCA to 4-pin Molex)
  • Amplifier Quick Setup
  • Certificate of Performance Verification

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More details on the Rockford Fosgate TM400X4AD

Mark G.

Product Research



Overview: The Rockford Fosgate TM400X4ad is a 4-channel Power Series "moto-marine" amplifier with a rated power output of 100 watts per channel at 4-ohms or 2-ohms. This Element Ready amplifier can be used on motorcycles, ATVs, or boats, and can withstand harsh environmental conditions.

CEA-2006 Compliant: CEA-2006 is a system of testing and measurement methods for mobile audio amplifiers. This voluntary standard advocates a uniform method for determining an amplifier's RMS power output and signal-to-noise ratio. The criteria for measuring power uses a DC input voltage of 14.4 volts and the RMS power output is measured into a 4Ω load with 1% or less Total Harmonic Distortion plus noise (THD+N). CEA-2006 allows consumers to compare amplifiers and receivers under identical conditions. The CEA-2006-rated RMS power output is 100 watts RMS x 4 channels. Additionally the power output is 100 watts RMS x 4 channels into 2Ω and 200 watts RMS x 2 channels bridged (into 4Ω).

Element Ready: Rockford Fosgate's Element Ready Amplifiers are protected against dust, UV rays, and corrosion. Marine-grade, two-part epoxy-coated circuit boards are used to prevent corrosion due to exposure in moist and humid places. In addition, stainless hardware is used to help prevent rust and corrosion of all electrical connections.

Class-AD: The TM400X4ad features Rockford Fosgate's proprietary Class-AD technology, which allows the amplifier to produce more power with less current draw from the vehicle's charging system.

3-Stage Airflow: The amp's 3-stage airflow method efficiently rids the chassis of heat to keep the amplifier running cool. Dual fan forced induction pulls in fresh air. The air flows over the MOSFET transistors to cool them down, and out through the exhaust channel. The top and bottom heat sinks are decoupled, which allows the top to remain cool to the touch. At least 2-3 inches clearance should be provided around the fan intake and the exhaust vents to optimize air flow.

DSM (Discrete Surface Mount): High speed robotics are used in the manufacturing process to place 1% tolerance parts and large board traces. DSM improves the efficiency of the circuit, decreases cross-talk from other discrete components and lowers operating temperature.

CLEAN Set-Up: Rockford's integrated level setting technology, CLEAN (Calibrated Level Eliminates Audible Noise), replaces sophisticated test equipment with input/output clip LEDs, allowing you to match the source unit's output to the amp's gain, and optimize the amp's output. The input clip indicator works in conjunction with the audio source volume, illuminating red when the source reaches its clipping point. The output clip indicator works in conjunction with the input level dial on the amp, illuminating the appropriate color depending on the audio content used for the setup.


Input Level: The amplifier has dual input level controls for the front and rear channels, conveniently accessible from the top. To accommodate the varying range of signal levels from today's factory and aftermarket radios, the input levels are adjustable from 150mV to 12V. A small flat-head screwdriver (not supplied) is needed to adjust the levels.

Input Switch: With the input switch in the 2-channel position, connecting only the front inputs will send the signal to both the front and rear sections of the amplifier. In the 4-channel position, both front and rear inputs must be used.

Crossover: The amplifier has dual built-in Butterworth crossovers for the front and rear channels, variable from 50 Hz to 250 Hz with a slope of 12dB/octave. They can be independently set to high-pass, all-pass (full range), or low-pass operation. The rotary frequency settings can be adjusted with a small screwdriver.

Punch EQ: The amplifier has dual Punch EQ functions that change with the crossover switches. When the crossover is set to low-pass, the Punch EQ acts as a variable bass boost; 0 to +18 dB at 45 Hz. When the crossover is set to high-pass, the Punch EQ acts as a variable treble boost, 0 to +14 dB at 12.5 kHz. When the crossover is set to all-pass, both the bass and treble boost circuits are active.


Power Connections: The TM400X4ad's power, ground, and remote turn-on terminals are located on a single, removable plug. This allows you to quickly and easily connect or disconnect the amplifier. Each individual terminal on the plug is a captive c-clamp connector which will accommodate up to 8-gauge wire. A Phillips- or flat-head screwdriver (not supplied) is required to tighten/loosen the terminals.

Fuse: The amplifier does not have an on-board fuse. A 60-amp fuse should be placed on the power wire within 18" of the battery.

Speaker Connections: The amplifier is equipped with two speaker output harnesses, which connects to the amplifier via 4-pin plugs. The speaker wires should be spliced to the 16-gauge bare wires on the 8" pigtails. To bridge the amplifier, you should use the left front and rear positive and right front and rear negative terminals. The amplifier can also operate in 3-channel mode with the front channels wired in stereo and the rear channels bridged to mono.

Signal Input: The amplifier's Differential Inputs will accept either a line-level or speaker-level input on the Molex-style connector. The included input harnesses each have a 4-pin Molex plug and dual RCAs. Front and rear line-level signals can simply be connected via RCA cables from the source unit to the input harness. For a speaker-level signal, you can cut the RCA connectors from the input harness and splice the wires to the speaker wires of the source unit. When using a speaker-level input signal, the auto turn-on feature is active and the remote turn-on terminal becomes a 12 volt output, which can be used to turn on/off an additional amplifier or other component.

Optional Custom Mounting Kit: The optional RFKHD9813 amplifier installation kit is designed for custom-mounting the TM400X4ad to compatible Harley-Davidson motorcycles. The kit includes a mounting plate, heatsink, and wiring kit. You may qualify for a One-Year Extended Warranty when you install the TM400X4ad with a matching Rockford Fosgate Amplifier Installation Kit.

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Customer Q&A

10 questions already asked

If I bridge this amp, do I only need to use the front inputs only and set the 2 channel switch to 2 chanel to run it bridged?
jason  Apr 08, 2024
1 answer
Hey Jason, if you do plan on bridging this amp, then front inputs with the 2 channel switch will be the way to go since that just needs a 2ch input that will sum the signal across all four channels.
red  Apr 08, 2024 (Staff)
This amp can be used ina car just as much anything else correct??
sarah  Feb 10, 2024
1 answer
You can use marine/powersports rated amplifiers in a vehicle Steven. These marine rated amps come with additional moisture and shock protection, so they are a good choice in vehicles that see off-road or top-down use.
bo  Feb 10, 2024 (Staff)
Will this amplifier fit in my 2003 Harley Davidson Ultra Classic Electra Glide under the fairing on top of the factory radio ?
leroy  Jun 14, 2022
1 answer
Greetings Leroy, and thank you for your question. Unfortunately we do not have access to your motorcycle to look above the radio and see if there is enough room to stack an amplifier. The dimensions of the amp are 8-5/8"D x 1-11/16"H x 4-5/16"W. You will have to pull your radio out and take the measurements to be sure.
hogan  Jun 14, 2022 (Staff)
How do you tune amp on the TM400X4ad? I see it has a disc. But I am only running threw Bluetooth without head unit. On 2013 road king with speaker lids
keenan  Sep 22, 2021
3 answers
I had a shop to install mine
reginald  Oct 04, 2021
Just for information purposes, I have a dual Amp running in my Ultra limited CVO with 8 speakers, 4 speakers on each Amp. At first I followed the standard set up posted in the manual. That didn't work for me. It blew a set of speakers. What I did is I picked the song with with most base on my list and played it at 80% volume without distortion; this allowed me to to tune my amps to my music. knowing that as long as I play it at 80% volume my speakers will not blow up. Now, I didn't start straight at 80% to do the tuning, first 40% looking for the perfect sound, than 50% and so on... The power of the Amp is higher than what the speaker can take, so I played balancing that power vs the songs I played. I listen to Rock and Regaton. If by my mistake I play RAP there is an immediate distortion that could blow up my speakers (because of the amount of base on that genre). Once again. It has to do more with MY SET UP than the song. Once again, I setup my amps to the type of music I listen to. Good luck.
jorge l tupac  Sep 27, 2021
YouTube has the sound frequencies avalable that you want to use (ie 400Hz).
jason  Sep 25, 2021
Can you run 2ohm speakers with this amp?
gary  Apr 17, 2021
1 answer
This amp is 2 ohm stable on each channel allowing a total of four 2 ohm speakers to be connected to it
jason  Apr 28, 2021 (Staff)
How many speakers can I put on there?
doug  Jan 01, 2021
2 answers
I got 4 speakers but a friend of mine is running 8
wesley  Jan 01, 2021
Well I'm running this amp in my Harley Street Glide. 2 6x9s n my rear saddle bags . 1ea. Then 4 in my fwd. Fairing. N each speaker side and I removed 2 small gages and installed 2 Twitter.
rickie j.  Jan 01, 2021
Is flashing required by the Harley shop if installed in a 2013 Ultra Classic with stock Radio but updated speakers Hertz up front and Rockford in rear with this Amplifier?
randy  Dec 30, 2019
3 answers
I installed the amp, rears and new fronts and did not get the flash. Worked perfectly.
terry  Jan 10, 2020
I didn't need to on my deluxe. I didn't have a system before.
jim  Jan 10, 2020
No that should not require any flashing. You will either use the speaker level inputs or a line output converter. If you want help putting together a complete installation package you can connect with one of our friendly product advisors here:
casey  Jan 10, 2020 (Staff)
I have a 2019 Kawasaki Vulcan Voyager. I want to add the TM400X4AD to drive 2 6.5 in and 2 5.25 in Polk Audio rated up to 100 RMS. I am keeping the stock radio unit. Will I have cut factory wiring to install this amp? Or does the Fosgate install kit eliminate that for me?
christopher  May 11, 2019
1 answer
You will have to modify the stock wiring to install an amp to the stock radio but could leave all the stock wiring in place and just tap into the speaker wire coming off it to get the signal to send to an amp like this one. Here's the tap connectors to use: My Bio:
jason  May 26, 2019 (Staff)
I have a Harley Davidson 2016 street glide. The wiring that comes with this amp include Harley harnesses for quick plug and play? If so, does the wiring come with a bridged harness? Thanks,
keef kruz  Apr 20, 2018
3 answers
every thing you need come with this amp plug and play
rickey  May 05, 2018
The amp itself does not. You need to purchase the Rockford fosgate rfkhd kit as well. Makes install a breeze. All plug and play. I purchase these along with the saddlebag speaker kit because I was worried the fairing speakers alone wouldn't be loud enough. Boy was I wrong. Now with all 4 speakers it's VERY loud and sounds great
shawn  May 02, 2018
The amp doesn't come with a Harley specific harness, you will need an install kit for that
anthony  May 02, 2018
Does this work with the rfkhd9813 amp kit?
bo  Jan 15, 2016
1 answer
Yes, you can use the Rockford Fosgate RFKHD9813 Installation Kit to install this amplifier. My Bio:
david  Jan 17, 2016 (Staff)

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