JL Audio M4500 Owner's Manual page 7

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).
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. For precise
(page 15).
Bi-Amplified System with one M4500 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 amplifiers have this feature.
In this configuration, channels 1&2 of the M4500
will drive front component speakerswith high-
rear component speakers in stereo, also with
high-pass filtering. The separate amplifier
will drive the subwoofer system with low-pass
filtering (80 Hz is a good starting point).
Input connection options for a bi-amplified
system with one M4500 and a separate subwoofer
amplifier 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
CH 1 (Left)
CH 2 (Right)
1&2 CH 3&4 Input From
inputs to the preamp outputs of the M4500
1&2 Pre-Outs Input From
switch. Alternatively, the M4500 can receive its
input from the subwoofer amplifier's preamp
full-range
Res ult: the relative level of the LF and front
and rear HF channels will be fixed by the
Input Sens.
subwoofer amplifier's settings) and will not be
user adjustable from the front of the vehicle.
12
B) Fade Subwoofer Level vs. HF Level:
Req uired: a source unit or processor with front
and rear pairs of stereo outputs.
Inp ut Connections: one stereo pair of source unit
CH 1 (Left)
CH 2 (Right)
1&2 CH 3&4 Input From
The second stereo pair of source unit outputs
is connected to the subwoofer amplifier
inputs.
Res ult: 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 M4500's
Input Sens.
adjustable from the front of the vehicle.
C) Subwoofer Level Control Only:
Req uired: a source unit or processor with left,
right 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 M4500 (select 1&2 on the CH 3&4
Input From switch). The source unit's
dedicated subwoofer output is connected to
the subwoofer amplifier inputs.
Res ult: 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.
JL AUDIO M4500
D) Front to Rear HF Fading and Subwoofer
Level Control:
Req uired: a source unit or processor with
front and rear pairs of stereo outputs plus a
dedicated subwoofer output.
Inp ut Connections: one stereo pair of source unit
outputs is connected to the CH 1 (Left) and
CH 2 (Right) inputs of the M4500.
The second stereo pair of source unit
outputs is connected to the CH 3 (Left)
and CH 4 (Right) inputs of the M4500
(select Discrete on the CH 3&4 Input
From switch). The source unit's dedicated
subwoofer output is connected to the
subwoofer amplifier inputs.
Res ult: 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.
JL AUDIO M4500
Set the subwoofer amplifier's "Input Sens."
with the source unit's subwoofer level control
set at 3/4 of full output.
Crossover Setup for Bi-Amplified System with
one M4500 and a separate subwoofer amplifier:
Once the input and preamp output sections
have been configured appropriately, go to the
Channel 1 & 2 Controls and Channel 3 &
4 Controls You will set both control sections
identically to start:
Select HP (high-pass) on the Filter Mode
switch and an appropriate Filter Freq. (80 Hz is
a good starting point). Make these adjustments to
both control sections.
After proper adjustment of the M4500's
Input Sens. controls, and the subwoofer
amplifier's input sensitivity controls, you can fine
tune filter frequencies and attenuate either pair
of channels to achieve proper balance. For proper
adjustment of the Input Sens. controls of the
M4500 use the method shown in Appendix A
(page 14). For precise filter frequency information
Refer to the subwoofer owner's manual for
proper adjustments.
13