JL Audio J2250.1 - Manual (Page 7)

7
IMPORTANT
!
Make sure you observe correct polarity in
making the “High-Level Input” connections.
Failure to do so will result in a complete loss of
signal (no bass).
The connections for the “High-Level Inputs” plug
wires are as follows from left to right on the plug:
White: Left Positive (+)
White/Black: Left Negative (–)
Black: Common Ground (rarely used)*
Gray: Right Positive (+)
Gray/Black: Right Negative (–)
*The only time you will use the “Common
Ground” connection is with some older (pre-
1980’s) factory systems or head units that ground
their speakers to chassis ground. To use this
connection, ground the black wire on the plug to
chassis ground and only connect the Left and Right
Positive plug wires to the factory radio outputs.
IMPORTANT
!
If you plan to use the preamp outputs to feed a
stereo amplifier, you must connect a stereo
signal to the input of the amplifier. A mono
signal into the amplifier will result in a mono
signal out of the preamp output.
“inPut sensitiVitY” (gain) adJustment
Located next to the input connectors is a rotary
control labeled “Input Sens.”. This rotary control
can be used to match the source unit’s output
voltage to the input stage of the amplifier for
maximum clean output.
LP Filter Frequency (Hz) Input Sens. Bass Boost
Power Protect
Remote
Level Port
LEFT
RIGHT
LEFT
RIGHT
Preamp
Outputs
Amplifier
Inputs
min max 60 240 Off +9dB
High-Level Inputs
Rotating the control clockwise will result
in higher sensitivity (louder for a given input
voltage). Rotating the control counter-clockwise
will result in lower sensitivity (quieter for a given
input voltage). To properly set the amplifier for
maximum clean output, please refer to Appendix
A (page 12) in this manual. After using this
procedure, you can then adjust the level of the
amplifier by adjusting the input sensitivity
downward, if the amplifier requires attenuation to
achieve the desired system balance.
Do not increase the “Input Sens.” setting for
any amplifier in the system beyond the maximum
level established during the procedure outlined
in Appendix A (page 12). Doing so will result in
audible distortion and possible speaker damage.