JL Audio HD600/4 - Manual (Page 7)

12 | JL Audio - HD600/4 Owner’s Manual 13
PreamP outPuts
The HD600/4 incorporates a pass-through
preamp output section, so that additional
amplifiers can easily be connected to the same
signal(s) feeding the HD600/4. These preamp
output signals are accessible via a stereo pair
of RCA-type jacks, labeled “Preouts”, on the
Connection Panel.
Rear Preouts Remote
Level
Control
Front Inputs
L
R
L
R
+12 VDC Ground Remote
The term “pass-through” refers to the fact that
the Preamp Output signals are not affected by any
crossover filter or input sensitivity setting selected
on the HD600/4 (if the input signal is full-range,
the Preamp Output will be full-range). These
preamp output signals are buffered to prevent
noise and are always preamp level, regardless of
the level of signals feeding the HD600/4’s inputs.
The pass-through Preamp Outputs can be
configured two different ways using the switch
labeled “Preouts From” in the “General Setup”
section of the Control Panel.
1) “Front”: The preamp output delivers the same
signal that is connected to the HD600/4’s
“Front Inputs”. This mode is useful for
feeding a subwoofer amplifier when the
HD600/4 is being used to drive front and rear
speaker systems. In this mode, the preamp
output level will track with the signal level
of the front input signals, allowing the user
to fade the rear channels in and out, without
affecting the subwoofer level.
3) “F+R” (Front + Rear): This mode delivers a
sum of the signals being fed to the “Front
Inputs” and the “Rear Inputs” of the
amplifier. When the HD600/4 is being used
to drive front and rear speaker systems, this
preamp output mode will deliver a summed
front/rear signal to the subwoofer amplifier,
while permitting fading of the front and rear
speaker systems from the source unit.
remote leVel Control (oPtional)
With the addition of the optional Remote Level
Control (HD-RLC), you can control the volume
of one or both channel pairs of the HD600/4
from the front of the vehicle. This is useful for
subwoofer level control or even as a master
volume control for the system.
The HD-RLC connects to the jack labeled
“Remote Level Control” on the Connection
Panel of the amplifier using a standard telephone
cable (supplied with the HD-RLC).
If desired, multiple HD amplifiers can be
controlled from a single HD-RLC controller
using a simple phone line “splitter” and multiple
phone cables.
Rear Preouts
Remote
Level
Control
Front Inputs
L
R
L
R
+12 VDC Ground Remote
When connected to the amplifier, the HD-RLC
operates as follows. At full counter-clockwise
rotation, the audio will mute completely. At full
clockwise rotation the level will be the same as if
the HD-RLC was not connected at all. In other
words, it operates strictly as a level attenuator.
Depending on the application, you may want
the HD-RLC to only affect one channel pair or
both channel pairs. A switch labeled “Remote
Level Control” in the “General Setup” Section
of the Control Panel allows you to determine
whether the HD-RLC affects the level of all
channels “All Ch.” or only the rear channels
“Rear Ch.”
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 HD600/4 can be configured to drive a
bi-amplified system by itself or with a separate
subwoofer amplifier.
bi-amplified system with one Hd600/4
In this configuration, the “Rear” channels
of the HD600/4 will drive subwoofers
(stereo 150W x 2 or bridged 300W x 1) with
low-pass filtering. The “Front” channels
will drive component speakers in stereo
(150W x 2) with high-pass filtering.
Crossover Setup for Bi-Amplified System
with one HD600/4:
Once the input sections have been configured
appropriately, go to the “Rear Channel Controls”
Section. Select “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
Channel Controls” Section. and select “HP”
(high-pass) on the “Filter Mode” switch and
“12dB” or “24dB” on the “Filter Slope”
switch and an appropriate “Filter Freq.”
(again, 80-90 Hz is a good starting point).
After proper adjustment of the Front and
Rear channel “Input Range” and “Input
Sens.” controls using the method shown
in Appendix C (pages 18, 19), 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 B (page 18).
bi-amplified system with one
Hd600/4 in four-channel mode and
a separate subwoofer amplifier
This configuration requires that the
separate subwoofer amplifier has a built-in
low-pass filter. In this configuration, the
“Front” channels of the HD600/4 will drive
front component speakers (stereo 150W x 2)
with high-pass filtering. The “Rear” channels
will drive rear component speakers in stereo
(150W x 2) with high-pass filtering.
The separate subwoofer amplifier will drive the
subwoofer system with low-pass filtering (select a
filter frequency of 80-90 Hz to start). The inputs
of the subwoofer amplifier can be fed from the
HD600/4’s preamp output or from a dedicated
subwoofer output on the source unit.
Crossover Setup for Bi-Amplified System with one
HD600/4 and a separate subwoofer amplifier:
Once the input and preamp output sections
have been configured appropriately, go to the
“Front Channel Controls” Section. Select “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).
Next, turn your attention to the “Rear
Channel Controls” Section and select “HP”
(high-pass) on the “Filter Mode” switch and
“12dB” or “24dB” on the “Filter Slope” switch
and an appropriate “Filter Freq.” (again, 80-90 Hz
is a good starting point).
After proper adjustment of the HD600/4’s and
the subwoofer amplifier’s “Input Range” and
“Input Sens.”, 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 HD600/4 use
the method shown in Appendix C (pages 18, 19).
For precise filter frequency information for the
HD600/4 refer to Appendix B (pages 18). Refer to
the subwoofer amplifier owner’s manual for its
proper adjustment levels.