Multi Amplifier Systems - JL Audio M400/4-24V Owner's Manual

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. For precise filter frequency
information refer to Appendix B (page 15).

MULTI AMPLIFIER SYSTEMS

Using the "Preamp Outputs" of the
M400/4-24V, it is easy to configure many
different multi-amplifier systems.
The most common type involves the addition
of a subwoofer amplifier, such as the JL Audio
MHD750/1-24V. Common configurations
of such a system are described below.
Bi-Amplified System with one M400/4-24V 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
M400/4-24V will drive front component speakers
in stereo with high-pass filtering. Channels 3&4
will drive 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).
Here are three possible configuration options:
A) 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 outputs is connected to the "CH
1 (Left)" and "CH 2 (Right)" inputs of
the M400/4-24V (select "2 Ch." on the
"Input Mode" switch). 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 M400/4-
24V's "Input Sens." settings and will not be
user adjustable from the front of the vessel.
B) 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 M400/4-24V (select "2 Ch." on the
"Input Mode" 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.
C) 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 M400/4-24V.
The second stereo pair of source unit outputs
is connected to the "CH 3 (Left)" and "CH
4 (Right)" inputs of the M400/4-24V (select
"4 Ch." on the "Input Mode" switch). The
source unit's dedicated subwoofer output is
connected to the subwoofer amplifier inputs.
13