AMPLIFIERS
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 Thunder4244 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 Thunder4244, is used to match the amplifi-
er'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 postion. 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 units right negative (-)
Solid Grey = Source units right positive (+)
With the Smart-Engage™ auto-turn 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 Thunder4000 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
Thunder4244 has a separate gain control for front and rear channels.
6. Crossover Select – This switch controls the type of crossover configuration that you desire. The
Thunder4000 series 2-channel amplifiers include a defeatable 18dB/Octave 85Hz crossover that is
high pass/low pass or full range selectable. The Thunder4244 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.
White/Black = Source units left negative (-)
Solid White = Source units left positive (+)
Input Panel Layout
SPEAKER
FRONT IN SUM OUT REAR IN
LEVEL
INPUT
FRONT
L
L
AMP
RCA
FRONT
GAIN
XÐOVER
INPUT
R
R
2CH 4CH
FR HP
RÐ LÐ
R+ L+
SPEAKER
LEVEL
INPUT
REAR
AMP
REAR
XÐOVER
GAIN
LP FR HP
RÐ LÐ
R+ L+