MTX Audio 342, 502, 942 Installation, Adjusting the Gain, Typical Speaker Wiring Configurations

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POWER AMPLIFIER OWNER’S MANUAL

Installation

Any deviation from the connection specifications recommended may cause serious damage to the amplifier, speakers and/or vehicle electrical system. Please double-check the connection before turning the system on.

1.Disconnect the vehicle’s negative battery connection.

2.Place your Thunder amplifier at the predetermined mounting location. Using a felt pen, mark the exact position of the mounting holes on the mounting surface. Set the amplifier aside. Use a sharp, precise blade to cut small circles in the carpet and padding around the four marks denoting your mounting holes to expose the metal underneath. Use a center punch to make an indentation in the metal to ensure that you drill the exact position for the screws. Drill the four holes as marked.

3.Temporarily mount your Thunder amplifier using the four (4) screws provided.

4.Run a power cable from the vehicle’s battery through the firewall and through the interior of the vehicle connecting one end to your Thunder amplifier’s +BATT terminal and connect the other end to the positive post on the battery.

Note: Install a circuit breaker/fuse within 18" of the battery. This effectively lowers the risk of severe damage to your vehicle should a short circuit ever occur in the audio system. Do not install the fuse in the fuse hold- er until all installation steps have been completed.

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 34 of maximum.

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

4.Adjust the gain control down until audible distor- tion disappears.

5.Follow steps 3-4 for other gain control settings if applicable.

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

Typical Speaker

Wiring Configurations

Stereo Amplifier

Bridge Mode Application

Impedance Requirement

4 ohm bridge minimum

2 ohm stereo minimum

 

 

8 ohm

 

 

 

4 ohm

 

 

 

8 ohm

 

 

 

4 ohm

 

 

 

 

 

 

 

 

 

 

 

 

 

+

- - +

 

 

+

- - +

 

 

L

L R R

 

 

L

L R R

 

 

 

AMP

 

 

 

AMP

 

Two 8 ohm Speakers

Two 4 ohm Speakers

 

 

 

 

 

 

 

not

OK ok

5.

Find a good ground spot on the vehicle’s chassis and remove the paint to reveal bare metal at the contact

 

point. Attach the ground wire to that contact point and connect the other end of the ground wire to the

 

GND terminal of your Thunder amplifier.

6.

Connect a Remote Turn-on wire from your source unit to your Thunder amplifier’s REM terminal (14 or 16

 

gauge wire). If your source unit does not have a dedicated Remote Turn-on lead, you may connect to the

 

source unit’s Power Antenna lead.

Troubleshooting Guide

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

7.

Connect RCA cables from your source unit to your Thunder amplifier’s RCA input jacks. If RCA (low level)

 

output is not available, connect the included speaker (high level) connector to the speaker wires from the

 

source unit.

8.

Connect your speakers to your Thunder amplifier’s speaker terminals using 12 gauge minimum speaker

 

cable.

9.

Double-check all the previous installation steps, in particular, the wiring and component connections.

 

Securely mount the amplifier. If everything is in order, reconnect the vehicle’s negative battery connec-

 

tion and begin adjusting your amplifier.

Note: Be sure that the Gain Level on the amplifier is turned all the way down (counter clockwise) before pro- ceeding with adjustments.

Common Oversights

The battery ground should remain DISCONNECTED at all stages of installation.

Do not begin drilling until you have put your Thunder amplifier aside. Using the amplifier as a drilling guide may cause irreparable damage to the amplifier and void your warranty.

Do not route any wires underneath or outside the vehicle body.

Route signal wires (RCAs from source unit, speaker wires, etc.) away from power wires (power, ground, etc.) to avoid ground loops and other sources of noise.

PROBLEM

CAUSE

No LED indication

No +12V at remote connection

 

No +12V at Power connection

 

Insufficient ground connection

 

Blown power fuse

LED on, no output

Volume on head unit off

 

Speaker connections not made

 

Gain control on amplifier off

 

Signal processing units off

 

All speakers blown

Output distorted

Head unit volume set too high

 

Amplifier gain set too high

Balance reversed

Speakers wired L + R reversed

 

RCA inputs reversed

Some balance reversed

Some Speakers wired L + R

 

reversed

 

Some RCA inputs reversed

Bass is weak

Speakers wired out

 

of phase

 

Not using MTX woofers

Blowing fuses

Excessive output levels

 

Amplifier defective

SOLUTION

Supply +12V to terminal Supply +12V to terminal Verify ground connection Replace fuse

Increase volume on head unit Make speaker connections Turn up gain

Apply power to signal processor Replace speakers

Lower head unit volume

Lower amplifier gain

Wire speakers with correct orientation

Reverse RCA input

Wire speakers with correct orientation

Reverse appropriate RCA inputs

Wire with correct phase

Buy MTX woofers

Lower volume

Return for service

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Contents Power Specifications Introduction FeaturesTroubleshooting Guide InstallationAdjusting the Gain Typical Speaker Wiring ConfigurationsInput Panel Layout Grey / Black = Source units right negativeSolid Grey = Source units right positive + Output Panel Layout ❶ ❷ ❹ ❸ ❹ ❸ ❷Caractéristiques FelicitationsComment Utiliser CE Manuel ’ampli est désormais étalonné par rapport à la source Réglage du volumeHaut-parleur standard Branchements Guide de dépannageAgencement du panneau d’entrée Gris/noir = Négatif droit de la sourceGris uni = Positif droit de la source Branchements sur connecteur de sortie Introducción Características CongratulacionesComo Usar Este Manual Guía para la solución de problemas InstalaciónDescuidos comunes Código de color del paquete de cables Diagrama del panel de entradaOhmios puenteadas Diagrama de la placa de salidaEinführung Technische Information WIR GratulierenZUR Verwendung Dieses Handbuchs Allgemeine Installationshinweise FehlersucheTrennen Sie das Minuskabel der Fahrzeugbatterie Drahtgeschirrfarbcodes Eingangskonsolen-LayoutAusgangskarte Abbildung For Warranty Inquiries, please call WarrantyNDM252