MTX Audio RT202, RT404 User Manual

AMPLIFIER

OWNER’S
MANUAL

RT202 RT404

AMPLIFIER OWNER’S MANUAL

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3

CONGRATULATIONS...

on your purchase of a new MTX Audio
Road Thunder Amplifier! MTX has long
been the industry leader in mobile audio,
and we have reached new heights with
the development of the new MTX Road
Thunder amplifiers. You couldn’t have
chosen a more reliable, powerful, or
better performing amplifier.

We manufacture every amplifier using
the latest Intelligent Surface Mount
Technology. Some of the advantages of

the new design are significant improve­ments to the amplifier’s electrical and
mechanical properties. ISMT devices feature
substantially shorter internal and external
lead lengths. This reduces stray capacitance
and inductance, which results in cleaner and
more accurate musical reproduction with sig­nificantly less noise interference. The ISMT
mounter produces amplifier boards with
smaller and lighter components, which are
more resistant to vibrations inherent in the
automotive environment.

We want to ensure you get continuous high
performance from your MTX Road Thunder
amplifier, so we recommend that you have it
professionally installed by your authorized
MTX dealer.

HOW TO USE THIS MANUAL

If you are installing this amplifier yourself, we
recommend that you read the manual cover­to-cover before you install it. Familiarize
yourself with the features and details on the
input and output panels. Make sure you have
all the equipment you need. Then follow the
step-by-step installation instructions included.
Sample installation diagrams may be found
on our website:

mtx.com

If you have any questions, write or call us:

MTX Audio

4545 E. Baseline Rd. Phoenix, AZ 85042

602-438-4545 • 800-CALL MTX

[e-mail]

mtx.com

Please take a moment to register your

purchase online at mtx.com.

Please, also record the serial number of
your amplifier in the space provided below,
and keep this manual for future reference,
as well as your sales receipt as proof of
ownership. (The serial number of your
amplifier is marked on the bottom of its
metal chassis.)

Serial Number:
Date of Purchase:

Introduction

ENGLISH

• Unique rubber Insulated Iso-Feet™

• Nickel-plated, heavy duty terminal block type connectors

• Speaker and low level inputs

• Input select 2CH/4CH switch on RT404 functions as a built-in Y connector

• Color-coded wire harness for speaker level input installation

• Smart-Engage™ auto-turn on for easy integration with factory head units

• Built-in, defeatable18dB/octave HP/LP crossover at 85 Hz

• RT404 front channel crossover is a defeatable18dB/octave, high pass, at 85Hz

• Adjustable input sensitivity

• Bridgeable, multi-channel circuit design

• Regulated PWM Mosfet Switching Power Supply

• New, more reliable high powered transformers

• Buffered, isolated output for daisy chaining multiple amplifiers

• Pure N-Channel Design

• Intelligent Surface Mount Technology

• Class A 100% discrete driver circuit topology

• Real-time computerized protection circuit

• Anti-shock PCB mounting design

• Acoustically Seamless Turn-on/Turn-off

Features

Specifications

RT202

RMS Power measured at 14.4 Volts DC:

37.5 Watts x 2 into a 4 Ohm load with < 1% THD
75 Watts x 2 into a 2 Ohm load with < 1% THD
150 Watts bridged into a 4 Ohm load with < 1% THD

Dynamic Power measured at 14.4 Volts DC:

50 Watts x 2 into a 4 Ohm load
100 Watts x 2 into a 2 Ohm load
200 Watts bridged into a 4 Ohm load

Signal to Noise Ratio: 100dB A-Weighted

(Referenced to Rated PWR at 1VRMS Input Sensitivity)

Frequency Response: 20-20,000 Hz ±.25dB
Crossover: Defeatable, 18dB/octave at 85 Hz,

selectable for high pass, low pass

Dimensions: Including Iso-Feet™

7.98" x 9.75" x 2.1" (20.3cm x 24.8cm x 5.3cm)

RT404

RMS Power measured at 14.4 Volts DC:

37.5 Watts x 4 into a 4 Ohm load with < 1% THD
75 Watts x 4 into a 2 Ohm load with < 1% THD
150 Watts x 2 bridged into a 4 Ohm load with < 1% THD

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

Signal to Noise Ratio: 100dB A-Weighted

(Referenced to Rated PWR at 1VRMS Input Sensitivity)

Frequency Response: 20-20,000 Hz ±.25dB
Crossover: Defeatable, 18dB/octave at 85 Hz,

selectable for high pass, low pass, or full range on
rear channels and high pass or full range for front
channels

Dimensions: Including Iso-Feet™

11.5" x 9.75" x 2.1" (29.2cm x 24.8cm x 5.3cm)

5

AMPLIFIER OWNER’S MANUAL

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1. RCA Input Jacks – These RCA input jacks are for use with source units that have RCA or Line Level
Outputs. An independent set of jacks are provided on the RT404 for front and rear stereo inputs. A source
unit with a minimum level of 200mV is required for proper operation. The use of high quality twisted pair
cables is recommended to decrease the possibility of radiated noise entering the system.

2. Input Select 2CH/4CH – This switch, found on the RT404, is used to match the amplifier’s input to the
source unit’s output so all four channels of the amplifier are driven. If your source unit has 2 outputs (left
and right) connect them to the amplifier’s front channel inputs, and place the input select switch in the 2CH
position. If your source unit has 4 outputs, (left front, left rear, right front, right rear) connect them to the
amplifier inputs and place the input select switch in the 4CH position. In the 4CH position, the fader on
your source unit will operate.

3. Speaker Level Inputs – This input will allow the amplifier to operate from source units with speaker level
outputs. Output speaker leads from the source unit should be tied directly to the wire harness provided
with the amplifier.

Wire harness color codes:
Grey/Black = Source unit right negative (-) White/Black = Source unit left negative (-)

Solid Grey = Source unit right positive (+) Solid White = Source unit left positive (+)

With the Smart-Engage™ auto-turn-on circuit, a remote turn-on wire is not necessary when connecting
the speaker-level input wire harness to a high powered source unit. The amplifier will automatically turn
on when music is received.

4. RCA Output – These RCA outputs allow for a signal to be sent to other amplifiers in a daisy-chain
configuration. The RCA outputs on all Road Thunder series amplifiers will send a full-range signal to
additional amplifiers.

5. Gain Controls – These controls are used to match the input sensitivity of the amplifier to the particular
source unit that you are using. The controls are factory set to 1Vrms. Note that the RT404 has a separate
gain control for front and rear channels.

6. Crossover Select – This switch controls the type of crossover configuration that you desire. Road
Thunder series 2-channel amplifiers include a defeatable 18dB/octave, 85Hz crossover that is high
pass/low pass or full range selectable. The RT404 four channel amplifier includes a defeatable
18dB/octave, 85Hz crossover that is high pass or full range for the front channels, and a high pass, low
pass or full range for the rear channels.

❷

❶

❸

❹

❺

❻

❶

❸

❻

❺

Input Panel Layout

❶

❸

❹

❺

❻

REAR IN

L

L

R

R

FRONT

GAIN

AMP

X–OVER

FR HP

RCA

INPUT

2CH 4CH

SPEAKER

LEVEL
INPUT
FRONT

R– L–
R+ L+

FRONT IN SUM OUT

SPEAKER

LEVEL
INPUT
REAR

R– L–
R+ L+

AMP

X–OVER

LP FR HP

REAR
GAIN

AMPLIFIER OWNER’S MANUAL

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1. Fuses - For convenience, all amplifiers utilize ATC type fuses. For continued protection in the event that
a fuse blows, replace the fuse only with the same value.
Caution: The power fuses on the amp are for protecting the amp against overdrive. To protect the vehicle’s
electrical system, an additional fuse is required within 18" of the battery on the 12V+ cable.

RT202 – 20 Amp
RT404 – 25 Amp x 2

2. Power Terminal – This is the main power input for the amplifier and must be connected directly to the

positive terminal of the car battery for the amplifier to operate properly. See the chart below for recom­mended cable sizes for each amplifier. Use caution when running this cable through the car. Try to avoid
the input RCA cables, antenna cabling, or other sensitive equipment as the large amount of current flow­ing through this cable can induce noise into your system. It is also very important to have a tight connec­tion to ensure maximum performance.

RT202 – 10 Gauge
RT404 – 8 Gauge

3. Ground Terminal – A good quality ground is required for your Road Thunder Amplifier to operate at peak

performance. A short length of cable the same gauge as your power cable should be used to attach the
ground terminal directly to the chassis of the car. Always scrape or sand any painted surfaces to expose
bare metal where the ground wire will attach.

4. Remote Terminal – All Road Thunder Amplifiers can be turned on by applying 12 volts to this terminal.
Typically this voltage is supplied by a wire from the source unit marked “remote” or “electric antenna”.

5. Speaker Terminals – As shown in the wiring diagrams, be sure to observe speaker polarity through the
system. Failing to wire the speakers in proper phase could result in a loss of bass response and/or poor
overall sound quality. Caution: Road Thunder amplifiers are not recommended for loads below 2 ohms

stereo or 4 ohms bridged.

6. Power LED - A lighted LED indicates that power has been applied to the amplifier. +12V from the battery
to the +BATT terminal and +12V from a switched ignition or remote lead from a head unit. An unlighted
LED indicates power has been removed or the amplifier has overheated. In the case of the overheat con­dition, the amplifier will turn back on after it cools down.

Output Panel Layout

❶

❺

❶

❷

❹

❸

❷

❹

❸

❺

❻

❻

AMPLIFIER OWNER’S MANUAL

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The following list of terms with their definitions is offered as
help in understanding the set-up and operation of your
amplifier.

1. Crossover (xover) - an electrical filter with high-pass or
low-pass characteristics that divides the frequency range
into playable bands for certain speakers. Subwoofers, mid­bass, midrange and tweeters are all designed to play differ­ent frequencies and should do so to avoid damage. The
xover point is where the playable frequencies cross from
one speaker to the next at -3dB below reference level.

2. Full-range - refers to signals which cover the entire audio
frequency span from 20Hz to 20kHz.

3. High-pass - simply put, this blocks lower frequencies
which damage smaller speakers, and passes the higher
frequencies for smaller speakers like the midrange and
tweeter.

4. Low-pass - you got it, this is the inverse of a high-pass. It
blocks higher frequencies and passes the playable lower
frequencies to the larger speakers, like subwoofers.

5. Impedance - the resistance to the flow of current in an
alternating current circuit (such as with music). Line level
circuits are typically a high impedance of several thousand
ohms, while speaker level circuits are usually a low imped­ance of a few ohms.

6. Line level - the type of signal produced at the outputs of
tape decks, CD tuners, preamplifiers, etc., with a typical
value of a volt or less in a high impedance circuit.

7. Speaker level - the type of output that is meant to drive
speakers. These signals are sometimes called high level
and are usually connected by two conductor speaker wires.

8. Signal - the signal of an audio system is what is heard
from the speakers. These signals may be high pass, low
pass or full-range.

We don’t have enough space for Electronics 101, so if you
have a good, bad or amusing question, please call us TOLL
FREE at 800-CALL MTX! (800-225-5689)

Adjusting the Gain

1. Turn the gain control on the amplifier all the way down.

2. Turn up the volume control on the source unit to
approximately

3

⁄4of maximum.

3. Adjust the gain control on the amplifier until audible distor­tion occurs.

4.

Adjust the gain control down until audible distortion
disappears.

5. Follow steps 3-4 for other gain control settings.
(RT404)

6.

The amplifier is now calibrated to the output of the
source unit.

Typical Speaker

Wiring

Configurations

Definitions of Common Terms

Read this if you wanna be a do-it-yourselfer or give us a call at 800-CALLMTX.

Problem

Cause Solution

No LED indication No +12V at remote connection Supply +12V to terminal

No +12V at Power connection Supply +12V to terminal
Insufficient ground connection Verify ground connection
Blown power fuse Replace fuse

LED on, no output Volume on head unit off Increase volume on head unit

Speaker connections not made Make speaker connections
Gain control on amplifier off Turn up gain
Signal processing units off Apply power to signal processor
All speakers blown Replace speakers

Output distorted Head unit volume set too high Lower head unit volume

Amplifier gain set too high Lower amplifier gain

Balance reversed Speakers wired L + R reversed Wire speakers with correct orientation

RCA inputs reversed Reverse RCA inputs

Some balance reversed Some Speakers wired L + R Wire speakers with correct orientation

reversed
Some RCA inputs reversed Reverse appropriate RCA inputs

Bass is weak Speakers wired out Wire with correct phase

of phase
Not using MTX woofers Buy MTX woofers

Blowing fuses Excessive output levels Lower volume

Amplifier defective Return for service

Troubleshooting Guide

Stereo Amplifier
Bridge Mode Application
Impedance Requirement

4 ohm bridge minimum
2 ohm stereo minimum

8 ohm

8 ohm

+ - - +
L L R R

AMP

Two 8 ohm Speakers

OK

4 ohm

4 ohm

+ - - +
L L R R

AMP

Two 4 ohm Speakers

not

ok

AMPLIFIER OWNER’S MANUAL

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Introduction

FELICITATIONS...

vous félicitant de votre achat d’un nou­veau amplificateur MTX Audio Road
Thunder! MTX a été depuis longtemps
un leader dans l’industrie d’enclos
mobiles et speakers, et nous sommes
arrivés à un nouveau sommet avec le
développement des nouveaux amplifi­cateurs MTX Road Thunder. Vous
n’auriez pas pu choisir d’amplificateur
plus fiable, plus puissant ou meilleur.

Nous fabriquons chaque amplificateur

en employant la Technologie Surface
Mount le plus récent et intelligent . Quelques
advantages du nouveau dessin sont les per­fectionnements aux propriétés mécaniques
et électriques de l’amplificateur. Les mécan­ismes SMT ont de substantiellement plus
courtes longueurs internes et externes. Cela
réduit l’inductance et la capacitance
égarées, qui résulte en une reproduction
musicale plus pure et plus exacte avec con­sidérablement moins d’intervention du bruit.
Le SMT mounter produit des cartes d’amplifi­cateur avec plus petits et plus légèrs com­posants qui sont plus résistants aux vibra­tions inhérentes dans l’environnement auto­mobile.

Nous voulons tout faire pour assurer que
vous obtenez la haute performance continue
de votre amplificateur MTX Road Thunder,
donc nous vous recommandons de l’avoir
installé professionellement par votre
vendeur agréé.

COMMENT UTILISER CE MANUEL

Si vous installez cet amplificateur vous­même, nous vous recommandons de lire ce
manuel de la première à la dernière page
avant de l’installer. Familiarisez-vous avec les
caractéristiques et les détails des panneaux
entrée-sortie. Vérifiez que vous avez tout
l’équipement dont vous avez besoin. Puis
suivez les instructions d’installation point par
point qui se trouvent. Vous pouvez trouver
des échantillons des diagrammes d’installa­tion sur le Web à notre site :

mtx.com

Si vous avez des questions, écrivez ou

téléphonez-nous à :

MTX Audio

4545 E. Baseline Rd.

Phoenix, AZ 85042

602-438-4545

800-CALL MTX

[e-mail]

mtx.com

• Iso-Feet™ uniques, isolants en caoutchouc

• Connecteurs nickelés, d’un type bloc terminal à usage industriel

• Speaker et les entrées de niveau bas

• Le contrôle Input Select 2CH/4CH sur RT404 fonctionne comme un connecteur Y encastré

• Harnais métallique codifié par couleurs

• Auto-allumage Smart-Engage ™ pour intégration facile avec les unités de tête d’usine

• Filtre passe-haut/passe-bas 18dB/octave contournable intégré à 85 Hz

•

Le croisement du canal avant

RT404

est un 18dB/octave défait (defeatable), haut laissez-passer, à 85Hz

• Sensibilité d’entrée réglable

• Possibilité de ponter l’ampli et trimode possible

• Source d’alimentation régulée à transistor Mosfet PWM régulé

• Nouveaux transformateurs haute puissance plus fiables

• Sortie isolée tamponnée pour la connexion en guirlande de plusieurs amplis

• Dessin N-Canal pur

• Technologie Intelligente Surface Mount

• Topologie de circuit moteur 100 % discret de classe A

• Circuit de protection informatisé temps réel

• Montage carte-mère antichoc

• Marche/arrêt transparent au plan acoustique

Caractéristiques

FRENCH

Specifications

RT202

RMS Power measured at 14.4 Volts DC:

37.5 Watts x 2 into a 4 Ohm load with < 1% THD
75 Watts x 2 into a 2 Ohm load with < 1% THD
150 Watts bridged into a 4 Ohm load with < 1% THD

Dynamic Power measured at 14.4 Volts DC:

50 Watts x 2 into a 4 Ohm load
100 Watts x 2 into a 2 Ohm load
200 Watts bridged into a 4 Ohm load

Signal to Noise Ratio: 100dB A-Weighted

(Referenced to Rated PWR at 1VRMS Input Sensitivity)

Frequency Response: 20-20,000 Hz ±.25dB
Crossover: Defeatable, 18dB/octave at 85 Hz,

selectable for high pass, low pass

Dimensions: Including Iso-Feet™

7.98" x 9.75" x 2.1" (20.3cm x 24.8cm x 5.3cm)

RT404

RMS Power measured at 14.4 Volts DC:

37.5 Watts x 4 into a 4 Ohm load with < 1% THD
75 Watts x 4 into a 2 Ohm load with < 1% THD
150 Watts x 2 bridged into a 4 Ohm load with < 1% THD

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

Signal to Noise Ratio: 100dB A-Weighted

(Referenced to Rated PWR at 1VRMS Input Sensitivity)

Frequency Response: 20-20,000 Hz ±.25dB
Crossover: Defeatable, 18dB/octave at 85 Hz,

selectable for high pass, low pass, or full range on
rear channels and high pass or full range for front
channels

Dimensions: Including Iso-Feet™

11.5" x 9.75" x 2.1" (29.2cm x 24.8cm x 5.3cm)