System Configurations - JL Audio JD 400/4 Owner's Manual

SYSTEM CONFIGURATIONS

The JD400/4 is a flexible amplifier, well-suited
for a multitude of system configurations. In this
section, the most likely configurations for a system
with a single JD400/4 are explained in detail.
Once you have selected your desired
configuration, you can use the amplifier panel
drawing on pages 18 & 19 to mark the required
switch positions for easy reference.
BI-AMPLIFIED SYSTEMS
Bi-amplified systems are defined as systems
in which separate amplifier channels drive low-
frequency (LF) and high-frequency (HF) speakers
and are separately filtered to send appropriate
frequency ranges to each speaker system.
The most common application of
bi-amplification in mobile audio is to drive a
subwoofer system from one or more amplifiers or
channels and component speakers from separate
amplifiers or channels.
The JD400/4 can be configured to drive a
bi-amplified system by itself or with a separate
subwoofer amplifier.
Bi-Amplified System with one JD400/4
In this configuration, channels 3&4 of the
JD400/4 will drive subwoofers (stereo or bridged)
with low-pass filtering. Channels 1&2 will
drive component speakers in stereo with
high-pass filtering.
Input connection options for a bi-amplified
system with one JD400/4 are as follows:
A) No User Adjustability:
Req uired: a basic source unit or processor
with one pair of stereo outputs.
Inp ut Connections: a single pair of stereo source
unit outputs connected to the "CH 1 (Left)"
and"CH 2 (Right)" inputs of the JD400/4
(select "2 Ch." on the "Input Mode" switch).
Res ult: the relative level of the LF and HF
channels will be determined by the JD400/4's
"Input Sensitivity" settings and will not be
user adjustable from the front of the vehicle.
B) Fade Subwoofer Level vs. HF Level
Req uired: a source unit or processor with two
pairs of stereo outputs.
Inp ut Connections: the first stereo pair of source
unit outputs is connected to the "CH 1 (Left)"
12
and "CH 2 (Right)" inputs of the JD400/4. The
2nd pair of source unit outputs connects to
the "CH 3 (Left)" and "CH 4 (Right)" inputs
(select "4 Ch." on the "Input Mode" switch).
Res ult: in this mode, the user has the ability to
fade or control the level of the LF channels
relative to the HF channels via the source
unit's fader control without exceeding the
maximum clean output level set by each
amplifier section's "Input Sens." controls.
C) Subwoofer Level Control Only:
Req uired: a source unit or processor with
one pair of stereo outputs and dedicated
subwoofer outputs.
Inp ut Connections: the main stereo pair of
source unit outputs is connected to the
"CH 1 (Left)" and "CH 2 (Right)" inputs
of the JD400/4. The source unit's dedicated
subwoofer output is connected to the "CH
3 (Left)" and "CH 4 (Right)" inputs (select
"4 Ch." on the "Input Mode" switch).
Res ult: in this mode, the user has the ability to
control the absolute level of the LF channels
relative to the HF channels.
Set the "Input Sens." in the "Channel 3 & 4
Controls" section with the source unit's
subwoofer level control set at 3/4 of full output.
See Appendix A (page 14) for details.
Crossover Setup for Bi-Amplified System
with one JD400/4:
Once the input sections have been configured
appropriately, go to the "Channel 3 & 4
Controls". Select "LP" (low-pass) on the "Filter
Mode" switch and an appropriate "Filter Freq."
(80 Hz is a good starting point).
Next, turn your attention to the "Channel 1 &
2 Controls" and select "HP" (high-pass) on the
"Filter Mode" switch and an appropriate "Filter
Freq." (again, 80 Hz is a good starting point).
After proper adjustment of the "Input Sens."
controls for both channel pairs using the method
shown in Appendix A (page 14), you can fine
tune filter frequencies and attenuate either
pair of channels to achieve proper balance.
JL Audio