Bass Boost Controls - JL Audio M4500 Owner's Manual

BASS BOOST CONTROLS

1) "CH 3&4 Bass Boost": Found in the "Channel
3 & 4 Controls" section, this switch allows the
user to activate a 6 dB boost centered at 48 Hz
for channels 3 & 4. When the "CH 3&4 Bass
Boost" is activated, the inputs to "CH 3 (Left)"
and "CH 4 (Right)" are summed to create a
mono signal. The "Filter Mode" switch in the
"Channel 3 & 4" section must be in the "LP"
position for the bass boost to be functional.
2) "Remote Bass Port": This port allows you to
connect an optional remote boost knob (sold
separately as JL Audio Model RBC-1) that
can be mounted near the head unit. With
the RBC-1 connected, the boost is no longer
limited to 0 or +6 dB, allowing a variable
range of 0 to +12 dB of boost to be selected.
PRE-OUTS
The M4500 incorporates a pass-through
preamp output section, so that additional
amplifiers can be easily added to the system. This
pass-through pre-amp output can be configured
two different ways using the switch labeled
"Pre-Outs Input From".
1) "1&2": The preamp output delivers the same
signal that is connected to the CH 1&2 Inputs.
This mode is useful for feeding a subwoofer
amplifier when the M4500 is being used to
drive front and rear speaker systems. In this
mode, the preamp output signal will depend
only on the input signal level of CH 1&2,
allowing Channels 3&4 to be faded without
affecting the subwoofer level. If CH 1&2 is
faded in this mode, the signal level of the
preamp output will change accordingly.
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2) "Sum": When the M4500 is being used to drive
front and rear speaker systems, this preamp
output mode will deliver a summed front/rear
stereo signal to a subwoofer amplifier, while
permitting fading of the front and rear speaker
systems from the source unit. This method
prevents a loss of signal to the subwoofer
amplifier when the system is faded to the front
or the rear by the head unit.
Note: Any signal delay between the front and rear
channels can result in a cancellation of signals
within certain frequency ranges when using the
"Sum" position. If you experience a loss of bass
output in the "Sum" position, compared to the
"1&2" position, you are likely dealing with a
delayed signal in either the front or rear outputs
of the source unit. If the front to rear delay is
desirable for other reasons or if it cannot be
defeated at the source unit, we recommend that
you use the "1&2" position.
Note: In either mode, the preamp output signal
is not affected by the "CH 3&4 Bass Boost"
processing selected for the amplifier or by any
crossover filter selected (if the input signal is full-
range, the preamp output will be full-range).
Note: The signal level of the "Preamp Output" is
line-level (low voltage), regardless of the position
selected in the M4500's "Input Voltage" switch.
An additional amplifier connected to these
preamp outputs should have its input voltage
switch set to the "Low" position.
JL AUDIO M4500