Filter Controls - JL Audio XD600/6 Owner's Manual

Filter Controls

Most speakers are not designed to reproduce
the full range of frequencies audible by the human
ear. For this reason, most speaker systems are
comprised of multiple speakers, each dedicated
to reproducing a specific frequency range. Filters
are used to select which frequency range is sent
to each section of a speaker system. The division
of frequency ranges to different speakers can be
done with passive filters (coils and/or capacitors
between the amplifier outputs and the speakers),
which are acceptable and commonly used
for filtering between mid-range speakers and
tweeters. Filtering between subwoofer systems
and satellite speaker systems is best done with
active filters, which cut off frequency content at
the input to the amplifier. Active filters are more
stable than passive filters and do not introduce
extraneous resistance, which can degrade
subwoofer performance.
The active filter built into each channel
section of the XD600/6 can be used to eliminate
potentially harmful and/or undesired frequencies
from making their way through the amplifier
sections to the speaker(s). This serves to improve
tonal balance and to avoid distortion and possible
speaker failure. Correct use of these filters can
substantially increase the longevity and fidelity of
your audio system.
8 | JL Audio - XD600/6 Owner's Manual
1) "Filter Mode" Control: The XD600/6 employs
a 12dB per octave filter for each pair of
channels (one filter for channels 1&2, another
filter for channels 3&4 and a third filter for
channels 5&6). Each of these filters can be
configured independently into one of two filter
types or defeated completely by way of the
three-position "Filter Mode" switches:
"Off": Defeats the filter completely, allowing
the full range of frequencies present at the
inputs to feed the amplifier. This is useful for
systems utilizing outboard active crossovers or
requiring full-range reproduction from one or
more of the XD600/6's channel pairs.
"LP" (Low-Pass): Configures the filter to
attenuate frequencies above the selected filter
frequency at a rate of 12dB per octave. This is
useful for connection of subwoofer(s) to one
or more of the XD600/6's channel pairs in a
bi-amplified system.
"HP" (High-Pass): Configures the filter to
attenuate frequencies below the selected filter
frequency at a rate of 12dB per octave. This is
useful for connection of component speakers to
one or more of the XD600/6's channel pairs in
a bi-amplified system.
2) "Filter Freq. (Hz)" The filter frequency
markings surrounding this rotary control
are for reference purposes and are generally
accurate to within 1/3 octave or better. If you
would like to select the filter cutoff frequency
with a higher level of precision, consult the
chart in Appendix B (page 15).
Tuning Hint: If you are using the XD600/6
to drive a subwoofer system ("LP" mode), a
component satellite speaker system ("HP" mode)
or both, 80 Hz is a good baseline "Filter Freq.
(Hz)" setting. After properly adjusting the "Input
Sens.", as outlined in Appendix A (page 14), you
can fine tune the "Filter Freq. (Hz)" control to
achieve the desired system frequency response.
remote leVel Control (oPtional)
With the addition of the optional Remote
Level Control (HD-RLC), you can control the
volume of one, two or all three channel pairs of
the XD600/6 from the front of the vehicle. This
is useful for subwoofer level control, rear channel
level control, center-channel level control or even
as a master volume control for the system.
The HD-RLC connects to the jack labeled
"Remote Level Control" on the Connection Panel
of the amplifier using a standard telephone cable
(supplied with the HD-RLC). If desired, multiple
XD (and HD) amplifiers can be controlled from
a single HD-RLC controller using a simple phone
line "splitter" and multiple phone cables.
When connected to the amplifier, the
HD-RLC operates as follows. At full counter-
clockwise rotation, the audio will mute
completely. At full clockwise rotation the level
will be the same as if the HD-RLC was not
connected at all. In other words, it operates
strictly as a level attenuator.
"Remote Level Mode" Switch: This switch
allows you to assign the operation of the
HD-RLC to one, two or all three pairs of
channels. In the "All" position, the HD-RLC
knob will affect all three channel pairs equally.
In the "3-6" (middle) position, only the level
of channels 3, 4, 5 and 6 will be affected by the
HD-RLC knob (channels 1 & 2 will not).
In the "5&6" position, only the level of
channels 5 and 6 will be affected by the HD-RLC
knob (channels 1, 2, 3 and 4 will not).
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