User Guide

Input Connections: The main stereo pair of source
unit outputs is connected to the front inputs of the
300/4 (select “2ch” on the “Input Mode” switch in
the “Front Input Section”).The source unit’s
dedicated subwoofer output is connected to the
subwoofer amplifier inputs.
Result: with this option, the user has the ability to
control the absolute level of the subwoofer channel
relative to the HF channels, but cannot fade the
front and rear HF channels relative to each other.
Set the subwoofer amplifier’s “Input Sens.” with
the source unit’s subwoofer level control set at 3/4
of full output.
D) Front to Rear HF Fading and
Subwoofer Level Control
Required: a source unit or processor with front and
rear pairs of stereo outputs plus a dedicated
subwoofer output.
Input Connections: one stereo pair (front, typically)
of source unit outputs is connected to the front
inputs of the 300/4. The second stereo pair of
source unit outputs (rear, typically) is connected to
the rear inputs of the 300/4 (select “4ch” on the
“Input Mode” switch in the “Front Input Section”).
The source unit’s dedicated subwoofer output is
connected to the subwoofer amplifier inputs.
Result: with this option, the user has the ability to
fade the front and rear HF channels relative to each
other and also has the ability to control the
absolute level of the subwoofer channel relative to
the HF channels.
Set the subwoofer amplifier’s “Input Sens.” with
the source unit’s subwoofer level control set at 3/4
of full output.
IMPORTANT
!
IMPORTANT
!
Crossover Setup for Bi-Amplified System with one
300/4 and a separate subwoofer amplifier:
Once the input and preamp output sections have
been configured appropriately, go to the “Front
Filter Controls” and “Rear Filter Controls” You will
set both control sections identically to start:
Select “x1” on the “Freq. Range” switch, “HP”
(high-pass) on the “Filter Mode” switch and “12dB”
or “24dB” on the “Filter Slope” switch and an
appropriate “Filter Freq.” (80 - 90 Hz is a good
starting point). Select the same settings for the
“Rear Filter Controls”.
After proper adjustment of the 300/4’s front and
rear “Input Sens.” controls, and the subwoofer
amplifier’s input sensitivity controls, you can fine tune
filter frequencies and slopes and attenuate either
pair of channels to achieve proper balance. For
proper adjustment of the “Input Sens.” controls of
the 300/4 use the method shown in Appendix B
(page 14). For precise filter frequency information
for the 300/4 refer to Appendix A (page 14). Refer
to the subwoofer amplifier owner’s manual for
proper adjustments.
JL AUDIO 300/4 13
Crossover Setup for Bi-Amplified System
with one 300/4:
Once the input sections have been configured
appropriately, go to the “Rear Filter Controls”.
Select “x1” on the “Freq. Range” switch, “LP” (low-
pass) on the “Filter Mode” switch and “12dB” or
“24dB” on the “Filter Slope” switch and an
appropriate “Filter Freq.” (80-90 Hz is a good
starting point).
Next, turn your attention to the “Front Filter
Controls” and select “x1” on the “Freq. Range”
switch, “HP” (high-pass) on the “Filter Type” switch
and “12dB” or “24dB” on the “Filter Mode/Slope”
switch and an appropriate “Filter Freq.” (again, 80-
90 Hz is a good starting point).
After proper adjustment of the front and rear
“Input Range” and “Input Sens.” controls using the
method shown in Appendix B (page 14), you can
fine tune filter frequencies and slopes and attenuate
either pair of channels to achieve proper balance.
For precise filter frequency information refer to
Appendix A (page 14).
BI-AMPLIFIED SYSTEM WITH ONE 300/4 IN
FOUR-CHANNEL MODE AND A SEPARATE
SUBWOOFER AMPLIFIER
This configuration requires that the separate
subwoofer amplifier has a built-in low-pass filter. All
JL Audio subwoofer amplifiers have this feature.
In this configuration, the front channels of the
300/4 will drive front component speakers (stereo
75W x 2) with high-pass filtering.The rear channels
will drive rear component speakers in stereo (75W
x 2), also with high-pass filtering.
The separate amplifier will drive the subwoofer
system with low-pass filtering (select a filter
frequency of 80-90 Hz to start).
Input connection options for a bi-amplified system
with one 300/4 and a separate subwoofer amplifier
are as follows:
A) No User Adjustability
Required: a basic source unit or processor with left
and right stereo outputs.
Input Connections: a single pair of stereo source
unit outputs is connected to the front inputs of the
300/4 (select “2ch” on the “Input Mode” switch in
the “Front Input Section”) and also connected to
the subwoofer amplifier inputs (via a “Y-Adaptor”).
Alternatively, the 300/4 can receive its input from
the subwoofer amplifier’s preamp output set to “full-
range” mode.
Result: the relative level of the LF and front and rear
HF channels will be fixed by the 300/4’s “Input
Sens.” settings (as well as the subwoofer amplifier’s
settings) and will not be user adjustable from the
front of the vehicle.
B) Fade Subwoofer Level vs. HF Level
Required: a source unit or processor with front and
rear pairs of stereo outputs.
Input Connections: one stereo pair of source unit
outputs is connected to the front inputs of the
300/4 (select “2ch” on the “Input Mode” switch in
the “Front Input Section”).The second stereo pair
of source unit outputs is connected to the
subwoofer amplifier inputs.
Result: with this option, the user has the ability to
fade the level of the subwoofer amplifier’s input
relative to the HF channels, but cannot control
front-to-rear fading of the HF channels.The relative
level of the front and rear HF channels will be fixed
by the 300/4’s “Input Sens.” settings and will not be
user adjustable from the front of the vehicle.
fading the signal to the subwoofer amplifier.
C) Subwoofer Level Control Only
Required: a source unit or processor with left, right
and dedicated subwoofer outputs.
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