JL Audio MD1000/1v2, Owners Manual/Install Manual

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8 | JL Audio -MD1000/1v2 Owner’s Manual
3) Precise Frequency Selection: The filter
frequency markings on the front panel of
the amplifier are for reference purposes and
are generally accurate to within 1/3 octave
or better. If you would like to select the filter
frequency with a higher level of precision,
consult Appendix B (page 13) of this manual.
This chart gives you a more accurate frequency
for each of the forty detented positions of the
frequency selection control. This method can
be very useful if the amplifier is mounted in
a location where you can’t see the front panel
markings easily.
4) Defeating the LP Filter: The Low-Pass filter
can also be defeated completely, by switching
the “LP Filter Mode/Slope” switch to the
“Off” position. This is useful if you are using
an external active crossover in the system.
With the internal crossover turned off, the
M1000/1v2’s upper frequency response limit is
500 Hz, due to its subwoofer-specific design.
INFRASONIC FILTER
The “Infrasonic Filter” is a 24 dB/octave high-
pass filter, with a fixed cutoff frequency of 30 Hz.
This filter is designed to conserve amplifier power
and protect subwoofer systems, without audibly
degrading the sub-bass output.
With ported enclosures and infinite baffle
subwoofer systems, the use of the “Infrasonic
Filter” is highly recommended to protect the
speaker(s) from excessive excursion at inaudibly
low frequencies.
With sealed enclosures, the use of the filter
is less necessary, but can still help protect the
speaker system from excessive excursion.
The “Infrasonic Filter” can be completely
defeated by selecting the “Off” position on its
switch. This bypasses all signal from flowing
through the circuit.