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Figure 20. Family of RMC depth curves (constant Q).
Typical RMC Families of Curves:
Both the LSR6328P full range system and the
LSR6312SP subwoofer incorporate a feature called
Room Mode Correction (RMC). RMC consists of a
single section of parametric equalization that can be
used to compensate for the rise in LF response
caused by a dominant room mode. The correction
frequencies range in tenth-octave increments from 26
Hz to 106 Hz, and up to 14 dB of cut may be
introduced into the system for compensation. The
width of the curves (Q factor) are likewise adjustable,
from 1/2 octave to 1/20 octave. The technique of
making the adjustments is covered in an analysis kit
available with the systems. Examples of the curve
families are shown in Figures 20 and 21.
Figure 21. Family of RMC width (Q) curves
at constant depth.
5. Detailed Performance of the LSR6325P
System:
Overview of System:
Two-way system with 133 mm (5.25 in) LF driver
Maximum peak level: 109 dB at 1 meter
LF boundary compensation and 80-Hz bypass
Nominal frequency response: 70 Hz – 20 kHz,
+1 dB,
−
2 dB
HF contours:
−
1, flat, +1 dB
Dimensions (W
×
H
×
D): 173
×
269
×
241 mm
(6.8
×
10.6
×
9.5 in)
Weight: 7.7 kg (17 lb)
Integral M6 mounting points
On-axis and Time Domain Performance:
The on-axis and time domain performance of the
LSR6325P are very similar to those of the LSR6328P,
as can be seen by comparing Figures 16 and 22. The
primary difference is the LF –3 dB point, which is 70
Hz for the LSR6325P and 50 Hz for the LSR6328P.
This allows the two models to be mixed effectively in
surround systems, where the rear channel LF program
content is often lower than that of the front channels.
Figure 22. Amplitude and phase response for the
LSR6325P system.
Distortion:
Distortion curves for the LSR6325P are shown in
Figure 23. At a fundamental level of 90 dB SPL at 60
Hz, the values of second and third harmonic
components are approximately 6.5%, which is
unusually low for a system as small as the LSR6325P.
Figure 23. Harmonic distortion at 96 dB SPL at
1 meter for the LSR6325P system.
HF and LF Contour Controls:
Figure 24 shows the response of LF and HF contours
in the LSR6325P. The HF contours of –1, 0, and +1 dB
further enable the system to be used in conjunction
with the LSR6328P with excellent response matching,
while the 80 Hz high-pass enables the system to be
used effectively with the LSR6312SP. A single position
of boundary compensation adjusts for system location
at or near a large boundary.
71800_JBL.TechNote
8/26/04, 7:58 AM
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