Operation Manual
4 Channel Amplifier - Speaker & RCA-Connection
GTR250.4 – GTR350.4
Subwoofer 4 - 8 Ohms
Subwoofer 4 - 8 Ohms
Connect RCA outputs
from head-unit with
RCA inputs (LINE
INPUT CH1/2).
CH3/4
CH1/2
LINE INPUT
R
R
L
L
LINE OUTPUT
LEVEL
5V
60Hz
60Hz
30Hz
30Hz
250Hz
250Hz
0dB
0dB
12dB
12dB
BASS BOOST
INPUT MO DE
2CH
4CH
X-OVER
0,2V
1.2kHz
1.2kHz
LP
BASS BOO ST
LEVEL
5V
0,2V
X-OVER
HP
FULL
HP
LP
HP
LP
CH3 / CH4
CH1/ CH2
3CH
LP
HPFULL
CH3 CH4
CH1 CH2
HIGH
INPUT
---
++
--
---
++
--
+++++
+++++
-----
-----
S
EAKE
R
P
O
UTP
U
T
e
1
3
225
01 7
F
U
S
E
BR
E
DI
G
D
L
R
G
N
D
R
E
M
1
2
V
WE
P
O
R
P
IN
UT
B
D
G
RI
E
D
L
R
R
P
O
T
T
E
C
P
EO
W
R
20
Caution
Please avoid to connect speaker (-) to the ground or vehicle chassis.
2-Channel-Mode: 2 Subwoofers / Mono
Cable connection
• Connect the INPUT of the amplifier to the head unit line output with good quality RCA cables.
If your head unit doesn't have RCA Outputs you can connect the Speaker Outputs of the head
unit with the HIGH INPUT of the amplifier.
• Connect the subwoofers with the terminal block (CH1/2 + BRIDGED - SPEAKER and
CH3/4 + BRIDGED - SPEAKER ) of the amplifier.
• The minimum final speaker impedance must not be below 4 Ohm per channelpair. Too low
speaker loads result in too high heat dissipation and may cause the amplifier run into
protection.
• Please observe speaker channel and polarity as printed by the speaker terminal block.
Incorrect phasing of the speakers results in total loss of bass response.
•
•
•
X-OVER - SWITCH & CONTROL (CH1/2 & CH3/4)
• In 2 Channel/Mono-Mode select at X-OVER "LP"-Position (LOW PASS), which eliminates the higher frequencies.
The recommended crossover frequency ranges between 60 - 150Hz, depending on the size and response of
ï the Subwoofer. The Lowpass adjustment can be done with the " LP" (LOW PASS) control.
• In this configuration example the "HP" (HIGH PASS) control is not used.
LEVEL CONTROL (CH1/2 & CH3/4)
• Turn the LEVEL control on the amplifier to "5V" position.
• Turn the head unit volume control to about 80-90% of its full setting.
• Turn the LEVEL control clockwise until you hear some distortion.
• Then turn back the LEVEL control slightly until you can hear clean sound.
BASS BOOST (only CH3/4)
• This Control increases the bass level at 45 Hz from 0db up to 12dB (only for subwoofer on CH3/4).
Caution! Please use the Bass-Boost carefully.
INPUT MODE
• The INPUT MODE switch must be in “2CH” - position.
ï
Green: Left Speaker -
White: Left Speaker +
Black: Ground
Brown: Right Speaker +
Gray: Right Speaker -
HIGH LEVEL INPUTS
CH1/2 & CH3/4
REV. 2