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tri-amPliFied sYstems
Tri-amplified systems are defined as systems
in which separate amplifier channels drive
low-frequency (LF), mid-frequency (MF) and
high-frequency (HF) speakers and are separately
filtered to send appropriate frequency ranges to
each speaker system.
The most common application of tri-
amplification in mobile audio is to drive a
subwoofer system from one or more amplifiers
or channels (LF channels), mid-range speakers
from a separate amplifier or set of channels
(MF channels) and high-frequency speakers
from a separate amplifier or set of channels
(HF channels). One such configuration is to
run subwoofers off the LF channel(s), mid-
bass speakers off the MF channels, and a
passively crossed over mid/high frequency
component speaker systems on the HF channels.
Another approach is to run subwoofers off the
LF channel(s), mid-woofers off the MF channels
and tweeters off the HF channels (all actively
crossed over).
By activating the CH 1&2 bandpass filter
feature, the 450/4v2 can easily be configured
to drive a tri-amplified system in conjunction
with a separate subwoofer amplifier that
includes a low-pass filter. CH 3&4 of the
450/1 will drive the HF speakers (75W x 2),
CH 1&2 will drive the MF speakers (150W
x 2) and the separate subwoofer amp(s)
will drive the LF speakers (subwoofers).
20 | JL Audio - 450/4
Owner's Manual
v2
Input connection options for the Tri-Amplified
Stereo mode are as follows:
A) No User Adjustability
Req uired: a basic source unit or processor with
left and right stereo outputs.
Inp ut Connections: a single pair of stereo
source unit outputs is connected to the CH
1&2 inputs of the 450/4v2 (select "2ch" on
the "Input Mode" switch in the "CH 1&2
Input Section"). Subwoofer amplifier inputs
are connected to the preamp outputs of the
450/4v2 (Select "1&2" on the "Signal From"
switch in the "Preamp Output Section").
Res ult: the relative level of all channels will be
fixed by the 450/4v2's "Input Sens." settings
and will not be user adjustable from the front
of the vehicle.
B) Fade Subwoofer Level vs. MF/HF Level
Req uired: a source unit or processor with front
and rear pairs of outputs is required.
Inp ut Connections: one stereo pair of source
unit outputs is connected to the CH 1&2
inputs of the 450/4v2 (select "2ch" on the
"Input Mode" switch in the "CH 1&2 Input
Section") and the second stereo pair of source
unit outputs is connected to the subwoofer
amplifier inputs. In this mode, the 450/4v2's
preamp output is not used.
Res ult: the user has the ability to adjust the level
of the subwoofer channel relative to the mid
and high-frequency 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 left, right and dedicated
subwoofer outputs is required.
Inp ut Connections: one stereo pair of source
unit outputs is connected to the CH 1&2
inputs of the 450/4v2 (select "2ch" on the
"Input Mode" switch in the "CH 1&2 Input
Section") and the source unit's dedicated
subwoofer output is connected to the
subwoofer amplifier inputs. In this mode, the
450/4v2's preamp output is not used.
Res ult: the user has the ability to control the
absolute level of the subwoofer channel
relative to the MF and HF channels.
!
IMPORTANT
Set the subwoofer amplifier's "Input
Sens." with the source unit's subwoofer
level control set at 3/4 of full output.
Refer to the subwoofer amplifier owner's
manual for proper adjustment.
Crossover setup for tri-amplified 3.1 system with
one 450/4v2 and a separate subwoofer amplifier:
Once the input and preamp output sections have
been configured appropriately, go to the "CH 1&2
Filter Section" of the 450/4v2. These settings
will determine the high-pass cutoff and slope of
the bandpass filtering applied to the MF (mid-
frequency) channels. Select "x1" on the "Freq.
Range" switch, "BP" (bandpass) on the "Filter
Type" switch and "12dB" or "24dB" on the
"Filter Mode/Slope" switch and an appropriate
"Filter Freq." (80-90 Hz is a good starting point).
The "Infrasonic Filter" and "Bass EQ" features
cannot be used in this mode.
Next, turn your attention to the "CH 3&4
Input Section". These settings will determine
the high-pass cutoff and slope of the high pass
filtering applied to the HF (high-frequency)
channels as well as the low-pass cutoff frequency
and slope for the MF channels' bandpass filter.
Select "x1" on the "Freq. Range" switch if your
desired MF to HF crossover frequency is below
500 Hz. Select "x10" on the "Freq. Range" switch
if your desired MF to HF crossover frequency
is above 500 Hz. Select "HP" (high-pass) on the
"Filter Type" switch and "12dB" or "24dB"
on the "Filter Mode/Slope" switch and an
appropriate "Filter Freq."
After proper adjustment of the 450/4v2's CH
1&2 and CH 3&4, and the subwoofer amplifier's
"Input Range" and "Input Sens.", you can fine
tune filter frequencies and slopes and attenuate
the LF, MF and HF channel pair or with the
"Input Sens." controls to achieve proper balance.
For proper adjustment of the "Input Sens."
controls of the 450/4v2 use the method shown in
Appendix B (page 22). For precise filter frequency
information for the 450/4v2 refer to Appendix
A (page 22). Refer to the subwoofer amplifier
owner's manual for proper adjustments.
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