POWER AMPLIFIER OWNER’S MANUAL
4
5
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
⁄
4
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.
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.
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.
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.
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 (Thunder342) 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.
Adjusting the Gain
Typical Speaker
Wiring Configurations
Stereo Amplifier
Bridge Mode Application
Impedance Requirement
4 ohm bridge minimum
2 ohm stereo minimum
AMP
+ - - +
L L R R
Two 8 ohm Speakers
OK
8 ohm
8 ohm
AMP
+ - - +
L L R R
Two 4 ohm Speakers
not
ok
4 ohm
4 ohm
Troubleshooting Guide
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
12V to terminal
No +12V at Power connection
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 input
Some balance reversed
Some Speakers wired L + R
Wire speakers with correct
reversed
orientation
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
