System Configurations - JL Audio iM700/5 Owner's Manual

sYstem ConFigurations

The M700/5 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 M700/5 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 M700/5 can be configured to drive a
bi-amplified system by itself.
bi-amplified system with one m700/5
In this configuration, the Subwoofer Channel
of the M700/5 will drive a subwoofer system with
low-pass filtering. The Main Channels (1&2, 3&4)
will drive component speakers in stereo with
high-pass filtering.
Crossover Setup for Bi-Amplified System
with one M700/5:
Once the input sections have been configured
appropriately (see page 6), go to the "SUB CH."
control section and select "12dB" or "24dB"
(low-pass) on the "LP Filter Mode" switch and
an appropriate "Filter Freq." (80 Hz is a good
starting point). The "12dB" setting engages a
shallow filter slope that gradually attenuates
frequencies above the selected "Filter Freq."
setting. The "24dB" setting engages a sharper
filter slope that more aggressively attenuates
frequencies above the selected "Filter Freq."
setting. Neither setting is "better", but in general,
the shallower "12dB" setting is more desirable
for a subwoofer having to interface with smaller
main speakers (6.5-inch or smaller). The sharper
"24dB" setting is typically better when interfacing
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with larger main speakers, like our 7.7-inch
components and coaxials. Experiment to find
the slope setting that results in the smoothest
subwoofer to midbass transition.
Next, turn your attention to the "CH 1 & 2"
Controls and select "x1" (high-pass) on the "HP
Filter Mode" switch and select an appropriate
"Filter Freq." (again, 80 Hz is a good starting
point). The "x1" setting means that the Filter
Freq. indicated on the dial is exactly what you are
selecting. (In the "x10" mode, the actual Filter
Frequency is ten times higher than the indicated
value. This setting is generally not used in
bi-amplified systems.)
Finally, turn your attention to the "CH 3 & 4"
Controls and select "HP" (high-pass) on the "Filter
Mode" switch and select an appropriate "Filter
Freq." (again, 80 Hz is a good starting point).
tri-amplified systems with one m700/5
The M700/5's 3-way crossover capability
allows you to create true, tri-amplified systems by
selecting the appropriate settings described below.
In a tri-amplified configuration, the
Subwoofer Channel of the M700/5 will drive
a subwoofer system, in mono, with low-pass
filtering. Channels 3 & 4 will drive component
woofers (or mid-range speakers) in stereo
with bandpass filtering (both a high-pass
and a low-pass filter applied). Channels 1 & 2
will drive high-frequency speakers (tweeters,
typically), in stereo, with high-pass filtering.
To operate a single M700/5 in Tri-Amplified
mode, set the "Input Mode" switch in "2 Ch."
mode, and apply a single set of stereo inputs to the
Ch. 1 & 2 Inputs only!
Crossover Setup for Tri-Amplified System
with one M700/5:
First go to the "SUB CH." control section
and select "12dB" or "24dB" (low-pass) on the
"LP Filter Mode" switch and an appropriate
"Filter Freq." (80 Hz is a good starting point). The
"12dB" setting engages a shallow filter slope that
gradually attenuates frequencies above the selected
"Filter Freq." setting. The "24dB" setting engages
a sharper filter slope that more aggressively
attenuates frequencies above the selected "Filter
Freq." setting. Neither setting is inherently
"better", but in general, the shallower "12dB"
setting is more desirable for a subwoofer having to
interface with smaller main speakers (6.5-inch or
smaller). The sharper "24dB" setting is typically
better when interfacing with larger main speakers,
like our 7.7-inch components and coaxials.
Experiment to find the slope setting that results in
the smoothest subwoofer to midbass transition.
Next, turn your attention to the "CH 3 &
4" Controls and select "BP" (bandpass) on
the "Filter Mode" switch. A bandpass filter is
actually composed of two filters (one high-pass
and one low-pass), which in combination allow a
defined "band" of frequencies to pass through the
amplifier channels and onto the speakers. These
are ideal for actively filtered mid-bass or mid-
range speakers in automotive sound systems.
Now that you have engaged Bandpass Mode
for Channels 3 & 4, select an appropriate "Filter
Freq." (again, 80 Hz is a good starting point).
The Filter Frequency you are adjusting with this
control is the high-pass portion of the bandpass
filter. The low-pass portion is automatically set by
the tweeter channel's "Filter Freq." adjustment
(CH 1 & 2). The low-pass portion of the bandpass
filter will always track with the CH 1 & 2 "Filter
Freq." setting.
Finally, turn your attention to the "CH 1
& 2" Controls and select "x10" (high-pass)
on the "HP Filter Mode" switch. This switch
position multiplies the indicated "Filter
Freq." value by a factor of 10, so that an
indicated frequency of 500 Hz is actually a
filter frequency of 5000 Hz (5 kHz). The filter
slope for this section is fixed at 12dB/octave.
Now, select an appropriate "Filter Freq." for
your tweeters (5000 Hz is a good starting point).
Before attempting any lower frequency settings,
consult the documentation for the tweeters you
are using and make sure you will not be driving
the tweeters with frequencies lower than they are
designed to handle. JL Audio mobile component
tweeters should not be operated with Filter
Frequencies lower than 3 kHz.
After proper adjustment of the "Input
Sens." controls for both main channel
pairs and the subwoofer channel 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)
To operate two M700/5's in Tri-Amplified
mode (one for left channel and the other for right
channel), set the "Input Mode" switches of both
amplifiers in "2 Ch." mode, and apply the left
channel signal to both the left and right inputs of
the first amplifier's Channel 1 & 2 Inputs, using
an RCA y-adaptor with one female and two male
ends. Then apply the right channel signal to both
the left and right inputs of the second amplifier's
Channel 1 & 2 inputs, using a second RCA
y-adaptor with one female and two male ends.
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