DA 1002 (serv.man9) - JBL Car Audio User Guide / Operation Manual. Page 5

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Left +: White
Left –: White with black stripe
Right +: Gray
Right –: Gray with black stripe

3. If you are connecting your Decade

Series amplifier to a source unit with
output voltage higher than 4V, connect
the output signal wires of the source
unit to the floating ground factory head
unit inputs.

Electronic Crossover
The electronic crossover in your Decade
Series amplifier (DA4002, DA6502 and
DA3504) can be selected as a 12dB/oct.
high-pass filter (HP) at 120Hz or a low-
pass filter (LP) at 80Hz, or defeated
(FLAT). The electronic crossover in the
DA1002 is a low-pass filter at 70Hz or
100Hz, and may be defeated.

Setting Input Sensitivity
Proper input sensitivity control settings
on Decade Series power amplifiers are
critical to ensure optimum performance,
low noise levels and maximum system
reliability. As a general rule, controls at
the front end of a system (source, equali-
zers and other processors) should be set
as high as possible with the amplifier
input sensitivity set as low as possible
while still providing adequate volume
levels. Using a high signal level and a low
sensitivity setting will help keep backgro-
und noise in the system to a
minimum.

Initially, turn the input sensitivity GAIN
control to its minimum (counter-clockwi-
se) position.
1. Reconnect the (–) negative lead to your

vehicle’s battery. Apply power to the
audio system and play a favorite music
track from a CD or tape. (Note: After the
source unit is on, the JBL badge (on the
top panel) will illuminate, indicating the
amplifier is on. If not, check the wiring,
especially the remote connection from
the source unit. Also refer to
“Troubleshooting” on page 7.)

2. On the source unit, increase the volume

control until it is approximately 3/4 of its
maximum output level. Slowly increase
the Input Sensitivity control (clockwise)
toward three o’ clock and, at the same
time, listen to the quality of the reprodu-
ced sound. 

At some point, you’ll hear distortion on

the music peaks. Stop the adjustment
and turn it back slightly. This is the
maximum undistorted output level of
your system, and should not be excee-
ded during use. 

3. After adjusting the level of the main

speakers in your system, you should
adjust the remaining channels (if you
are using a DA3504 or a multi-amp 
system) for the desired system balance.
You’ll find this easiest to do by adjus-
ting the channels in the following order:
1) front speakers, 2) rear speakers, 3)
subwoofer. Elaborate, multi-channel
systems may be too complex to adjust.
Your local JBL installation specialist is
the best person to help with such adjus-
tments.

 35633_Decade DA 4002, Eng  04/11/98  11:02  Side 5