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| JL Audio - RD900/5 Owner’s Manual
SYSTEM CONFIGURATIONS
The RD900/5 is a very flexible amplifier, well-
suited for a multitude of system configurations.
In this section, the most likely configurations for
a system with a single RD900/5 are explained
in detail.
Once you have selected your desired
configuration, you can use the amplifier panel
drawing on pages 18 & 19 to mark the required
switch positions for easy reference.
BI-AMPLIFIED SYSTEMS
Bi-amplified systems are defined as systems
in which separate amplifier channels drive low-
frequency (LF) and high-frequency (HF) speakers
and are separately filtered to send appropriate
frequency ranges to each speaker system.
The most common application of
bi-amplification in mobile audio is to drive a
subwoofer system from one or more amplifiers or
channels and component speakers from separate
amplifiers or channels.
The RD900/5 can be easily configured to drive
a complete bi-amplified system consisting of a
subwoofer and four main speakers or a subwoofer
and two main speakers.
Bi-Amplified Systems with one RD900/5
driving four main speakers plus subwoofer
(5-Channel Mode)
In this configuration, the Main Channels (1&2,
3&4) will drive component speakers (stereo 70W
x 4 @ 4Ω) with high-pass filtering. The Subwoofer
Channel will drive a subwoofer system (225W x 1
@ 4Ω or 500W x 1 @ 2Ω) with low-pass filtering.
Once the input sections have been configured
appropriately (see page 7), go to the “CHANNELS
1 & 2” controls section and select an appropriate
“HP Filter Freq. (Hz)” (80-90 Hz is a good
starting point). Next, turn your attention to
the “CHANNELS 2 & 3” controls section and
select an appropriate “HP Filter Freq. (Hz)” (80-
90 Hz is a good starting point). Finally, in the
“SUBWOOFER CHANNEL” controls section,
select a “LP Filter Freq. (Hz)” of 80-90 Hz.
After proper adjustment of the RD900/5’s
“Input Voltage” and “Input Sensitivity” controls,
you can fine tune filter frequencies and attenuate
each channel section to achieve proper balance.
Bi-Amplified Systems with one RD900/5
driving two main speakers plus subwoofer
(3-Channel Mode)
In this configuration, “CHANNELS 1 & 2” of
the RD900/5 will be bridged to drive the left front
component speakers (200W x 1 @ 4Ω) with
high-pass filtering. “CHANNELS 3 & 4” will
be bridged to drive the right front component
speakers (200W x 1 @ 4Ω), also with high-pass
filtering. The “SUBWOOFER CHANNEL” will
drive the subwoofer system (225W x 1 @ 4Ω
or 500W x 1 @ 2Ω) with low-pass filtering. For
information on proper bridging techniques, refer
to the section titled “Bridging Considerations” in
this manual (pages 9-10)
Once the input sections have been configured
appropriately (see page 7), go to the “CHANNELS
1 & 2” controls section and select an appropriate
“HP Filter Freq. (Hz)” (80-90 Hz is a good
starting point). Next, turn your attention to
the “CHANNELS 2 & 3” controls section and
select an appropriate “HP Filter Freq. (Hz)” (80-
90 Hz is a good starting point). Finally, in the
“SUBWOOFER CHANNEL” controls section,
select a “LP Filter Freq. (Hz)” of 80-90 Hz.
After proper adjustment of the RD900/5’s
“Input Voltage” and “Input Sensitivity” controls,
you can fine tune filter frequencies and attenuate
each channel section to achieve proper balance.
Keep in mind that the left and right front speakers
will have independent “Input Sensitivity” controls
in this configuration, and these need to be
carefully matched for proper stereo performance.
