JBL LSR6300 - Manual (Page 12)

LSR6312SP Powered Subwoofer System
12
The LSR6312SP Active Subwoofer consists of a Neodymium Differential Drive NDD™ 12"
neodymium woofer integrated with a powerful 260 watt continuous power output amplifier.
The active drive circuitry has been developed to maximize the acoustic output power while
maintaining overall low distortion and excellent transient performance. The enclosure is
manufactured with a molded baffle and rigidly braced MDF enclosure for low resonance and
minimal box loss. The Linear Dynamics Aperture (LDA) Port design minimizes port turbulence
and eliminates port compression.
Active crossover electronics supply 4th-order electroacoustic slopes to the low pass subwoofer transition to reduce the possibility of
audible localization of the subwoofer. This allows greater flexibility in placement for optimum operation in a wide variety of rooms. Since
low frequency energy supplied by the LSR6312SP is essentially omnidirectional, placement of the unit(s) is more dependent upon room
acoustics and interaction than localization issues.
The active electronics includes switchable high pass filters for the front satellite speakers. This option is used to filter low frequency
information from the front speakers and redirect this information to the subwoofer. This is usually the case when the front speakers
cannot reproduce extended low frequency information at the desired sound pressure level, or to optimize the low frequency perform-
ance of the system in the room. Alternatively, if the front channels are operated in full range, the bypass function can be enabled allow-
ing the subwoofer to be muted. The bypass function allows the LSR6312SP direct LFE input to remain active.
RMC Equalization
There are three screwdriver adjustable controls on the rear panel of the LSR6328P indicated RMC. The term RMC stands for Room
Mode Correction, which consists of a single section cut-only parametric equalizer that can be adjusted in frequency, width (Q) of cut,
and the amount of cut. It is used to reduce the magnitude of any dominant low frequency peak in response due to standing waves at
the listening position. Details of Room Mode Correction are presented in the user guide included with the RMC Claibration Kit.
Audio Connections
The LSR6312SP subwoofer contains both input and output XLR connectors for three channels, which are typically Left, Center and
Right. An additional direct input is included which is active at all times. It This allows routing for a separate signal directly to the input
electronics of the LSR6312SP, as well as the summed low frequency response of the Left, Center and Right inputs. The inputs are
shipped with a sensitivity of -10 dBV, but this can be changed +0, +4 dBu, +8 dBu or +12 dBu by moving a dip switches on the back of
the unit. A 12 dBu variable input trim can be switched in to calibrate input sensitivity to a precise setting. The outputs transmit either full
range or high-passed program information, depending on the mode of the subwoofer. The summed output transmits a sum of the L, C,
R and Direct input signals with no processing to allow chaining of multiple LSR6312SP subwoofers. Positive voltage to Pin 2 of the XLR
will produce a forward motion in the low frequency cone. Shown below in Figures I and J are views of the rear electronics panel on the
LSR6312SP and a signal flow diagram for the system. We recommend that you study these drawings in detail.
LSR6312SP
Linear Spatial Reference
Powered Subwoofer
Input Trim Active
+4 dBu Input Sensitivity
+8 dBu Input Sensitivity
Signal Polarity Inverted
-4 dB Bass Alignment
RMC Defeat
Left In Right In Left Out Center Out Center In Right Out Sub-Direct In
Option Active
With Switch Up
0 dB
+10 dB
With Differential Drive® Transducer Technology
U.S. Patent Nos. 5,748,760 and 5,828,767
Other U.S. and Foreign Patents Pending
Input
Trim
Sensitivity
0
dB Cut
Figure I