JBL 305P MkII, Owner'S Manual

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15
CROSSOVER SETTINGS AND BASS MANAGEMENT
“Bass management” is a term that refers to the practice of using a subwoofer to reproduce the bass frequencies
of the main channels. Because of the physiology of the human ear, low frequencies are largely non-directional.
Given an adequate listening distance, we can’t easily tell where bass signals are coming from. Thus, it makes
little or no difference to the listening experience whether the bass component in a sound comes from the
originating speaker—which may be off to your left or right, or even behind you—or from a dedicated subwoofer
which is better equipped and better positioned in the room to reproduce low frequencies. For that reason, you
may want to use an LSR310S subwoofer to reproduce all the bass frequencies in the system.
When using an LSR310S subwoofer in the system, bass management is accomplished by simply routing the
left and right mix channels to the LSR310S inputs and then from the LSR310S outputs to the left and right
speakers. The frequency at which the subwoofer divides signals to the sub and the left and right speakers can
be set using the CROSSOVER FREQUENCY selector switch on the input panel of the LSR310S.
The LSR310S offers three crossover settings:
• 80Hz
The 80Hz setting is recommended when the goal is a full range reference monitor system that accurately
portrays content below the cut-off frequency of the main speakers. The 80Hz setting provides a smooth
transition between the subwoofer and main speakers without audible localization of bass, creating the
perception of a full range system with no subwoofer.
• XLF
A trend in music production is the requirement for enhanced low frequency response in the control
room. Artists and producers involved in the production of dance music appreciate the ability to audition
their work as it might sound when played on a system with enhanced low frequency tuning, commonly
employed in dance clubs.
A JBL first, the LSR310S includes a special XLF (Extended Low Frequency) setting that emulates the
response curve applied to a club playback system. When the XLF crossover setting is selected, a 120Hz
high-pass filter is engaged in conjunction with a 10dB boost at 60Hz with a bandwidth of 0.5 octaves.
Using this setting, the bass output more than doubles and the character of the low frequency energy
approximates that of a club system.
Continuous low frequency energy with very high peak SPL is made possible by JBL’s new long excursion
low frequency driver, working in concert with JBL’s patented Slip Stream™ Port, and powered by a 200
watt Class-D amplifier. A protective circuit allows the LSR310S to continuously produce low frequencies
at high output levels without failure. In situations where positioning will allow, an additional 6dB of output
can be achieved by positioning the LSR310S subwoofer adjacent to a wall or at the intersection of two
walls.
•
External
Select this setting when connecting the subwoofer to an external active crossover. Note that when the
External option is selected, the XLR LEFT and RIGHT OUT connectors are disabled.
SURROUND SOUND SYSTEMS AND LFE
The LSR310S subwoofer can be used to reproduce the LFE (Low Frequency Effects) or .1 channel in a surround
sound system. In film production applications, the LFE channel contains low frequency effects, such as the
sounds of explosions and other sounds with a strong low frequency component. In music applications, the LFE
channel usually contains low frequency instruments such as bass, bass drum, and synthesizer elements.