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Monolith Version 2 Crossover
and Filtering Configuration
Suggestions
Although available from the factory in either a bi-amplified or
tri-amplified configuration, the Monolith Version 2 is most often
selected for bi-amp use. The following suggestions relate to the
bi-amplified configuration. In this configuration, the Monolith Version
2 loudspeaker requires separate amplifier channels for the LF and MF/HF
sections. Through testing and extensive listening tests, suggested
crossover and equalization parameters have been established. These
should be used simply as a guide, but are not “etched in stone.” It is
highly recommended that all settings be configured, and modified as
required, for each specific installation.
Crossover: For optimum performance
what is essentially an asymmetrical crossover configuration is desired.
This can be created several ways, but the best being a symmetrical
crossover filter combined with a notch filter. This should prove simple
to implement using virtually any of the DSP-based speaker processing
systems. Begin by configuring both the LF and MF/HF channels for a –6 dB
crossover point of 240 Hz. The slope of crossover filters should be 24
dB per octave, with a Linkwitz-Riley filter implementation preferred.
Then configure a –10 dB notch filter centered at about 190 Hz, with a
bandwidth of 0.40 (Q=2.5). This filter combines with the LF output’s
low-pass filter to create the desired asymmetrical crossover response.
Equalization: Besides the possible
use of one “notch” filter, suggested as part of the crossover
implementation, no equalization, such as notch filters or shelf filters,
is required for excellent sonic performance. For additional LF impact a
0.7 octave (Q=1.4) "bass bump" at 50 Hz can be implemented. Depending on
the taste of the listener, anywhere from +3 to +10 dB of equalization
(bump) can be very effective. The test listeners who liked to hear lots
of bass energy selected +10 dB as their preference. No high-frequency
horn compensation ("CD horn EQ") is necessary. But adding some if
desired will not cause a problem if judiciously selected.
Loudspeaker Protection: Implementing
a high-pass filter in the LF channel will provide protection for the
Monolith Version 2’s 18-inch woofer. This will prevent the woofer from
receiving low-frequency energy in the frequency band where it is not
capable of generating significant acoustic output. If not filtered out,
essentially all of the energy in this frequency band would simply be
dissipated in the voice coil as heat. Using a filter whose slope is 24
dB per octave, with a –6 dB point at 44 Hz would be appropriate. If
subwoofers are to be used with one or more Monolith Version 2’s,
selecting a higher –6 dB point, such as 80 Hz, will offer additional
protection. It will also allow the subwoofers to better perform their
intended role.
Practical Implementation: In this
example, two Monolith Version 2’s are used to provide full-range, stereo
reinforcement. The speaker processor selected was an XTA Electronics
DP224, configured in its 2 x 2 way crossover mode. For the crossover,
setting both the LF output’s low-pass filter and the HF output’s
high-pass filter to 241 Hz worked very well. The filter types were set
for Linkwitz-Riley, 24 dB per octave. The LF output had its high-pass
filter set for 44 Hz, again with a filter type of Linkwitz-Riley per 24
dB per octave selected. The HF output’s low-pass filter was left in its
22 kHz-default setting. In the LF output section, two filters were
configured. The first is a –10 dB notch centered at 191 Hz, with a
bandwidth 0.40 (Q=2.5). This filter combines with the LF output’s
low-pass filter to create the desired asymmetrical crossover response.
The second filter is a "bass bump" of +10 dB at 50 Hz, bandwidth 0.71
(Q=1.4). This creates very intense bass performance. With the
aforementioned configuration, the overall sonic performance of the
Monolith Version 2 was excellent. Other fine loudspeaker management
systems, such as from BSS or Ashly Audio, should be able to be similarly
configured.
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