MTX Audio Thunder Marine TM904

4-Channel Amplifier for Marine Use

Discontinued
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This item has been discontinued

But you may be interested in the newest model that's available.

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MTX WET75.4

OUR PRICE: $229.95

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  • Thunder Marine Series 4-Channel Class AB Marine Amplifier
  • RMS Power Rating:
    • 4 ohms: 45 watts x 4 chan.
    • 2 ohms: 75 watts x 4 chan.
    • Bridged, 4 ohms: 150 watts x 2 chan.
  • Max power output: 900 watts
  • MOSFET power supply
  • LED power indicators
  • Preamp RCA outputs
  • Conformal coated circuit board
  • Sealed covers keep amplifier controls and speaker terminals dry. Impact resistant grilles protect the speakers while still looking great.
  • Gold-plated screw terminals
  • Defeatable high-pass filter and low-pass filter (85 Hz, 18 dB/octave)
  • Subsonic Filter (24 dB at 15 Hz)
  • CEA-2006 compliant amplifier
  • Frequency response: 20-20000 Hz
  • Dimensions: 9-1/2"L x 10-13/16"W x 2-3/8"H
  • Authorized Internet Dealer
  • 1-year Manufacturer’s warranty

Product History:

MTX WET75.4 thumbnail
(newest, current model)
MTX TM904 thumbnail
(previous model, replaced by MTX WET75.4)

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.

45 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
RMS Power @ 1 ohm

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 1 ohm, 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.

Not Stable
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
Peak Power Output
This form of power rating refers to the maximum amount of power an electronic device can handle or output in an instant without damage occurring. Often times this maximum is achieved during a brief musical burst, such as a drum accent, or low bass hit.

Some manufacturers display peak power ratings on the face of their products to increase the appeal to consumers. The RMS power rating is more accurate, and we recommend using it for product comparison.

225 watts x 4 channels

Amplifier Specifications

Marine Certified
Marine certified means that the unit has been designed and manufactured with a marine use in mind. It will withstand the harsh conditions that come from marine use. Generally, they are treated against UV rays and treated with special protective coatings.
Yes
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 Peak Power Output
The total peak power output is measured as the wattage per channel multiplied by the number of channels, and is calculated at the lowest level of operating impedance.

It is measured during a brief musical burst, such as a sudden drum accent. Some manufacturers display peak power ratings on the face of their products to increase the appeal.

The RMS power rating is more accurate, and we recommend using it for product comparison.

900 watts
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%
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.
No
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.

85 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.

85 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.
78 dB
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.
No
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
Fuse Rating
The amperage and the number of fuse(s) an amp requires.
25A x 2 
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.

Yes

Specials with this Item

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Warranty and Return Policy

Parts Warranty Duration
1 year
Labor Warranty Duration
1 year
Warranty Provider
Manufacturer

Summary of Customer Ratings & Reviews

Rating Distribution

5 Star
50%
4 Star
50%
3 Star
0%
2 Star
0%
1 Star
0%

Average Attribution Rating

Durability
5.0
Value
4.0
Features
4.0
Design
4.5
Usability
5.0
E.A.M.M.

Ecuador

Overall
Durability
Value
Features
Design
Usability
lo mejor

February 1, 2012

I bought thunder mtx marine tm904. Amplifier is very good quality, and has the best sound, buy this product and you will not be disappointed.

0 of 0 found this helpful

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Mike

SoCal, CA

Overall
Durability
Value
Features
Design
Usability
Excellent Amp

November 30, 2011

I mounted the amp in my sand rail running a couple of Boss marine 6x9s, it's been performing very well with plenty of exposure to moisture, sunlight and lots of vibration. The only thing that would make this amp any better would be if MTX produced it in the USA. The quality is definately there, it's simply not made here, and made in the USA would make it awesome!

0 of 0 found this helpful

Help our customers find the most helpful reviews

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Product Summary

Manufacturer

Model Number

TM904

UPC

715442241026

Weight

8.00lbs

Internal SKU

tm904

Internal Product ID

10337

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: MTX Audio Thunder Marine TM904