10.
High Pass Filter (Full Range) - This controls the frequencies played for the front and rear
channels. Low frequencies can be cut off from 40Hz to 250Hz.
11.
X-Over Mode and Frequency Control (Full Range) - These controls allow control over the
frequencies played for the rear channels. There is an option for Low Pass, Full Range, or High
Pass. In LP or HP mode, the crossover frequency can be tuned from 40Hz to 250Hz.
12.
Power Indicator - This Blue LED will light up when the amplifier is working properly.
13.
Protection Indicator - This Red LED will light up and flash if there is a fault presented to the
amplifier. Please disconnect the amplifier and resolve the fault before reconnecting the amplifier.
14.
Remote Turn On - This unit features auto turn on technology allowing installation via high level
input without the use of a remote wire. If using a factory or aftermarket radio that does not
include RCA outputs, the amplifier can be connected to the source unit via high level speaker
wire via the high level input. The Remote Turn On switch when placed in the “Auto” position will
allow the unit to turn itself on without the need to connect a remote wire. In the “Ext” position the
unit will require a remote wire connection to turn on.
15.
Amplifier Strapping - Two units can be linked together to achieve a strapped 2 Ohm output. One
unit must have the switch in the Master position and the other must be in the Slave position.
Connect a single RCA interconnect from the Input/Output of the Master amplifier to the Input/
Output of the Slave amplifier. Connect the negative speaker output terminal from the Master to
the negative speaker output terminal on the Slave amplifier. Connect the positive speaker output
terminal from the Master amplifier to the positive speaker input terminal on the subwoofer or
terminal cup and the positive speaker output terminal from the Slave amplifier to the negative
speaker input terminal on the subwoofer or terminal cup. Use caution not to connect the negative
speaker output terminal on either amplifier to the ground or chassis.
PANEL LAYOUT
XTHUNDER125.4 4-Channel Amplifier Panel Layout
SPEAKER
OUTPUT
FRONT
FUSE
POWER INPUT
REAR
BRIDGE
L CH +
–
R CH +
–
L CH
R CH
R CH
L CH
FRONT
REAR
HI INPUT
REMOTE
LEVEL
BASS BOOST
XTHUNDER125.4
FREQ
LEVEL
BASS BOOST
FREQ
FRONT
X-OVER
REAR
POWER
P.T
LINE INPUT
L CH
EXT
AUTO
REMOTE TURN ON
5V
0.2V
0dB
18dB
40Hz
250Hz
HPF
FULL
LPF
LPF
HPF
FULL
5V
0.2V
0dB
18dB
40Hz
250Hz
+
–
R CH +
–
+12V
REM
GND
13
1
4
12
11
10
6
14
3
2
5
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