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6. Directivity index of early reflections.
Notice in particular how closely the on-axis response
and the averaged listening-window response track
each other.
Figure 1. LSR curve families. LSR6332 (A);
LSR6328P (B).
Figure 2 shows the LSR curve family for an earlier
three-way monitor that was designed primarily for flat
on-axis response. You can clearly see the irregularities
in the early reflection pattern and the total radiated
power, which translate directly into irregular reflected
signal at the listener.
The model LSR6332 is intended for both vertical and
horizontal mounting at the user's discretion. In order to
preserve the response shown in Figure 1A, the baffle
Figure 2. LSR curves for an earlier three-way model.
2
containing the MF and HF transducers can be rotated
as shown in Figure 3.
Figure 3. LSR6332 MF and HF baffle rotation for
horizontal or vertical mounting.
3. Transducer Development:
The LF drivers used in the LSR6332, LSR6328P, and
LSR6312SP systems make use of Differential Drive
topology. In addition, models LSR6332 and
LSR6312SP use neodymium magnets, a technique
that results in lighter weight, inherent magnetic
shielding, and lower distortion. Figure 4 shows a
section view of a Differential Drive transducer with the
two drive coils labeled.
Figure 4. Cutaway view, LF driver for LSR6332
system.
Located between the drive coils is a braking coil ; this is
a short-circuited coil that responds only when cone
excursions are at maximum. For normal modulation it
has no effect; but when high excursions are
encountered the braking coil enters the magnetic field
and acts to restrain cone motion. This action linearizes
cone displacement, resulting in lower distortion at high
operating levels, as indicated in Figure 5.
The midrange (MF) driver for the LSR6332 system is
shown in Figure 6. The driver has a neodymium motor
and is thus well shielded magnetically. The voice coil
has a diameter of 50 mm (2 in) for high power handling
capability. The cone is of woven Kevlar
®
®
, and the outer
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