High-level performance is what MTX amplifiers are all about. The sound pros at MTX subject each Thunder amp to rigorous bench testing before they'll let it ship, and they pack each model full of features designed with you, the music lover and audio enthusiast, in mind.

The Thunder404's versatile 4-channel design makes it ideal for a variety of applications, from powering four full-range speakers to driving a pair of subwoofers. You get plenty of power (50 watts RMS x 4, or 200 watts x 2 in bridged mode), plus selectable crossovers that keep your speakers operating at peak efficiency. Preamp outputs make it easy to add another amplifier to your system!

Heavy-duty, nickel-plated terminal block connectors promote effective transfer of current into the amp. Inside, high-powered transformers and patented PWM MOSFET switching power supplies give you maximum output for dynamic sound from your speakers. Intelligent Surface Mount Design ensures greater stability and low noise levels. What does all that technology mean to you? Clean, tight music, no matter how loud you like it.

Product Highlights:

  • 50 watts RMS x 4 at four ohms
  • 100 watts RMS x 4 at two ohms
  • 200 watts RMS x 2 bridged output at 4 ohms
  • 2-, 3-, or 4-channel output
  • 4-ohm stable in bridged mode
  • Tri-way capable (Tri-Way crossover required)
  • requires 4-gauge power and ground leads — wiring and hardware not included with amplifier
  • PWM MOSFET switching power supply
  • 85 Hz high-pass crossover on front channels, 85 Hz switchable high-pass/low-pass crossover on rear channels, 18 db/octave slope each
  • speaker-level inputs
  • preamp outputs
  • 11-9/16"W x 2-1/4"H x 9-13/16"D
  • 1-year warranty

My system has plenty of power. Who needs an amp?

You might think you don't need an amp because you have a 400-watt system in your car, or because your new stereo puts out 50 watts a channel. But those are peak wattage ratings, which may boil down to 15 or 20 watts per channel, using the more realistic RMS rating. An amp sends your speakers the power they need to deliver your music with clarity and impact, whether you're using factory speakers or high-performance components. And low-frequency reproduction requires lots of power, so an amp is an absolute must if you're adding a sub to your system.

MTX Thunder404 Reviews

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MTX Thunder404

Written By Russell, Vancouver, WA on Sunday, February 20, 2005

Well, since I didn't know what I was doing I bought two amps a profile 740 for the fronts and the rears in the car then I got the 404 road thunder for my sub's. I have the Road thunder hooked up to two Alpine SWE 1041 10" sub's, which are in a sealed box. and man does this setup hit's hard. My friend has four 12" mtx and at low to midium volume this setup hit just as hard and my sub aren't even broken in yet.

Hands-on research

What's in the box?

Download owner's manual

  • One 4-channel amplifier
  • 2 Speaker-level input harnesses
  • Owner's manual
  • Amplifier Input/Output Connections sheet
  • Amplifier Performance Certificate
  • MTX Audio sticker
  • Bridge Mode Impedance Requirement sheet (attached to inside packaging)

Product Research

Inputs and Outputs


Class A 100% Discrete Driver Circuit Topology: The preamp stages use Class A topology for low distortion and a high damping factor; the result is tight, controlled bass.

Patented PWM MOSFET Switching Power Supply:  This type of power supply is used for maximum power output and protection.

Pure N-Channel Design: The pure N-channel design is more linear than typical N-Channel designs, so the speaker you connect to the amplifier will be better controlled. The signal travels through fewer parts so the signal-to-noise ratio is enhanced, the power rating is better, and the amp runs louder, longer.

Smart-Engage: When using the speaker-level input, the amp automatically turns on when it senses signal from the head unit, eliminating the need for a remote turn-on connection. In many cases, this feature will allow you to install the amplifier without the need to remove your radio.

Input Select Switch: The input select switch, located on the left side of the amplifier, is used to match the amplifier's input to the source unit's output so all four channels are driven. If the source unit has only 2 preamp outputs (Left and Right), they should be connected to the amplifier's front channel inputs and the input select switch should be set to "2 CH". The amp's built-in "Y" adapter feeds the input signal to all four output channels. The source unit's fader does not function when the amplifier is wired this way. If the source unit has 4 preamp outputs (LF, RF, LR, RR), they should be connected to the amplifier's 4 inputs, and the switch placed in the "4 CH" position. The source unit's fader control will function properly when wired in this fashion.

Internal Crossovers: The amplifier has two built-in crossovers: one for the front channels and one for the rear channels. They are each 18dB/octave, 85Hz crossovers. The front crossover can be set for high-pass or turned off for full-range output. The rear crossover can be set for high-pass or low-pass operation, or it may be turned off for full-range output.

Preamp Outputs: There is one set of isolated, full-range preamp outputs for adding another amp. The output signal is a summed output of the front and rear channels.

Intelligent Surface Mount Technology: Features substantially shorter internal and external lead lengths, reducing stray capacitance and inductance, which results in cleaner and more accurate musical reproduction with less noise interference.

Real-time Computerized Protection Circuit: The protection circuit makes sure the amp is operating within safe parameters for maximum power and protection.

Acoustically Seamless Turn-on/Turn-off: A circuit that prevents turn-on/turn-off "thump" is included to eliminate turn-on/off noise.

Iso-Feet: Four rubber Iso-Feet are attached to the amplifier. The rubber feet let you mount the amp securely, while preventing the mounting screws from coming into contact with the amp's chassis; this helps prevent ground loops.

Terminals: The terminals are nickel-plated, heavy-duty screw terminal connectors.

Performance Certificate: MTX tests each amplifier, and the technician records the "actual" power output on the Certified Performance Certificate included with each amp. The amp must meet or exceed the rated specification in order to leave the factory.

Inputs and Outputs

Left Side of the Amplifier

  • Front Line-In: RCA stereo jacks
  • Rear Line-In: RCA stereo jacks
  • Sum Line-Out: RCA stereo jacks
  • Speaker Level Inputs: two 4-pin inputs for use with the included speaker-level input harnesses

Right Side of the Amplifier

  • BATT (power): screw terminal (terminal is 0.54" wide)
  • GND (ground): screw terminal (terminal is 0.54" wide)
  • REM (remote turn-on): screw terminal (terminal is 0.34" wide)
  • Speaker Outputs: screw terminals (each terminal is 0.34" wide)


Dynamic Power Measured at 14.4 Volts DC:

  • 50 watts x 4 into a 4 Ohm load
  • 100 watts x 4 into a 2 Ohm load
  • 200 watts x 2 bridged into a 4 Ohm load

RMS Power Measured at 12.5 Volts DC:

  • 35 watts x 4 into a 4 Ohm load with less than 1% THD
  • 70 watts x 4 into a 2 Ohm load with less than 1% THD
  • 140 watts x 2 bridged into a 4 Ohm load with less than 1% THD

Our Product Research Team

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