Our take on the MTX X Thunder 704X

by Buck Pomerantz

The distinctive chrome MTX logo and heavy-duty end panels let you know that X Thunder amps mean business. Their large extruded aluminum heatsinks and anodized finish keep these durable amps running cool even under extreme listening conditions.

The X Thunder 704X amplifier pushes out 70 watts RMS to each of four speakers, or it can be bridged to run 210 watts RMS into two channels. This amp includes high- and low-pass filters that let you adjust the amp's output to fit your speaker system.

Highlights:

4-channel car amplifier
70 watts RMS x 4 at 4 ohms (105 watts x 4 at 2 ohms)
210 watts RMS x 2 bridged at 4 ohms
CEA-2006 compliant
variable high-pass filter (40-8,000 Hz at 12 dB per octave) and low-pass filter (40-5,000 Hz at 24 dB per octave)
speaker- and preamp-level inputs
fuse rating: 30A x 2
4-gauge power and ground leads recommended — wiring and hardware not included with amplifier
14-15/16"W x 2-1/4"H x 9-5/8"D
warranty: 1 year
Our 60-day money-back guarantee

Hands-on research from the Crutchfield Labs (what are the Labs?)

Features and specs chart | What’s in the box? | In-depth notes

Features and Specs

Performance
RMS Power Output (Watts x Channels) Loading...	70 x 4
Peak Power Output (Watts x Channels) Loading...	210 x 4
Power at 2 Ohms (Watts x Channels) Loading...	105 x 4
Bridged Power (Watts x Channels) Loading...	210 x 2
Minimum Impedance Bridged Loading...	4
Minimum Impedance Unbridged Loading...	2
Best Frequency Response Loading...	20-20k Hz
THD at Rated RMS Power Loading...	1%
Signal to Noise Ratio Loading...	75 dB
Input Voltage Loading...	14.4v
Features
Amplifier Class Loading...	AB
Low-Pass Crossover Frequency Loading...	40-5000 Hz
Low-Pass Slope (dB/octave) Loading...	24dB/oct
High-Pass Crossover Frequency Loading...	40-8000 Hz
High-Pass Slope (dB/octave) Loading...	12dB/oct
Bass Boost Loading...	No
Bass Boost Frequency Loading...	N/A
Fan Cooled Loading...	No
Fuse Rating Loading...	30 x 2
Speaker Level Inputs Loading...	Harness x 2
Preamp Outputs Loading...	No
Width (inches) Loading...	9-5/8
Height (inches) Loading...	2-1/4
Depth (inches) Loading...	14-15/16
Parts Warranty Loading...	1 Year
Labor Warranty Loading...	1 Year

Product Research

What's in the box?

Download owner's manual

4-Channel amplifier with two 30-amp fuses inserted in chassis
2 Speaker level input harnesses
4 Mounting screws
3mm Allen-wrench
4mm Allen-wrench
Amplifier Performance Certificate
Installation sheet with warranty statement

Our Product Research Team

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Features
Controls
Inputs and Outputs

Features

CEA-2006 Compliant: CEA-2006 is a new system of testing & 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 4-ohm load, with 1% or less Total Harmonic Distortion (THD) plus noise, and at a frequency range (for full range amplifiers) of 20 Hz to 20,000 Hz. Signal-to-Noise ratio is measured in weighted absolute decibels (dBA) at a reference of 1 watt into 4 ohms. CEA-2006 allows consumers to compare car amplifiers and receivers on an equal basis. The MTX X-Thunder 704X under CEA-2006 regulations is rated at 70 Watts RMS x 4 channel with a 75dBA signal to noise ratio.

Bridgeable: The MTX four-channel amplifier can be bridged down to two channels to output 210 watts x two-channels at 4 ohm or bridged to three channels to output 70 watts x two-channel at 4 ohm to the front channels and 210 watts x one-channel at 4 ohm to the rear channel.

Heavy Duty Construction: The X-Thunder amplifier features heavy duty aluminum construction with large extruded heat-sinks for reliable sound for years to come.

Crossovers: The X-Thunder 704X has built-in independent high pass and low pass crossovers for the front (1/2) and rear (3/4) channels. The high pass crossover's slope is 12 dB/octave and is continuously variable from 40Hz to 8000Hz. The low pass crossover's slope is 24 dB/octave and is also continuously variable from 40Hz to 5000Hz. The amplifier can also be operated at full-range.

Line Level Inputs: The two pair of RCA type line-level inputs have independent gain (Input Sensitivity) control. The Input Sensitivity control will accept an input signal of 250mV to 5.0 Volts.

Speaker Level Input: The MTX 704X comes with two speaker level input harnesses. This feature makes it easier to add a four-channel amplifier to a factory radio or to an aftermarket receiver with no preamp outputs.

Power Indicator: When the power is turned on to the amplifier, the Power indicator on top of the amplifier will light up. This indicator will turn off with the amplifier and will turn off if the amplifier goes into protect mode.

Controls

Front of the Amplifier: All of the amplifier's controls are found on the front of the amplifier for easy access.

1/2-Channels and 3/4-Channels Gain: 0.25V-5V
1/2-Channels and 3/4-Channels High Pass Filter: On or Off
1/2-Channels and 3/4-Channels Low Pass Filter: On or Off
1/2-Channles and 3/4-Channels High Pass Frequency: 40-8,000 Hz
1/2-Channels and 3/4-Channels Low Pass Frequency: 40-5,000 Hz

Inputs and Outputs

Front of the Amplifier: All of the amplifier's connections are found on the front of the amplifier for easy access.

Fuse: Two 30 amp fuses
Power: set-screw terminal designed to accept up to a 4 gauge power wire
Ground: set-screw terminal designed to accept up to a 4 gauge ground wire
Remote turn-on: set-screw terminal designed to accept a 16-gauge turn-on lead
Speaker outputs: eight set-screw terminals designed to accept 12 to 8 gauge speaker wire
Speaker-level inputs: Multi-pin inputs for use with included speaker level input harnesses
Line in: Two pair RCA inputs

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1-5 of 5 items Sort Results By: Date Reviewed | Rating | Helpfulness

1 out of 5

Crapped out on me

Written By Lee3333, NYC on Tuesday, December 07, 2010

Worked good for a while then a few months ago I began hearing a sound like static as
if the radio station was not tuned in right (but I have Sirius and it also happened on
CD's) Using the balance and fader controls, I pinpointed the problem to the right front
speaker. A few days later, it stopped making any sound at all. To double check, I tried
hooking up a new speaker to each of the amp outputs, and the front right one was not
working at all. When I tried bridging it, the sound level was half that of the other channel.
Since it is a little over 2 years old, there is no warranty anymore.
Amps should last longer than that