Bang & Olufsen BeoVision Avant - Technical Sound Guide - Manual (Page 18)

18
Select this menu to move to the next
menu where parameters for the Bass
Management and Bass Redirection
systems can be adjusted
In a perfect sound system, all
loudspeakers are identical, and they are
all full-range. However, most often, this
is not an option. Luckily, it is possible to
play some tricks to avoid having to
install a large-scale sound system to
listen to music or watch movies.
Humans have an amazing ability to
localise sound sources. With your eyes
closed, you are able to point towards
the direction sounds are coming from
with an incredible accuracy. However,
this ability gets increasingly worse as we
go lower in frequency, particularly in
closed rooms.
In a sound system, we can use this
inability to our advantage. Since you are
unable to localise the point of origin of
very low frequencies, it should not
matter where the loudspeaker that’s
producing them is positioned in your
listening room. Consequently, we are
able to remove the bass from our ‘main’
loudspeakers and send them to a single
large loudspeaker that can produce the
bass for the entire system. This
loudspeaker is called a ‘subwoofer’ since
it is used to produce frequency bands
below those played by the woofers in
the main loudspeakers. The process of
removing the bass from the main
channels and re-routing them to the
subwoofer is called ‘bass management’.
Note that, although a bass management
system requires at least one loudspeaker
with low frequency capabilities such as a
subwoofer, it should not be confused
with an LFE or a ‘.1’ channel. However, in
most cases, the LFE channel from your
media (i.e. DVD or Blu-ray) will be
combined with the low-frequency
output of the bass management system
and the total result routed to the
subwoofer.
There are cases where some of the main
loudspeakers in a configuration are, in
fact, as capable (or more capable) than a
subwoofer for reproducing low
frequency content (for example, a
BeoLab 5 has much more potential to
deliver low frequency content than a
BeoLab 19 subwoofer). In this case, it
does not make sense to send low
frequencies to the subwoofer, since the
main loudspeakers will perform better
in the same role. Consequently, it is
smarter to re-direct the bass
information to one or more main
loudspeakers in the system instead of to
a single subwoofer. This is the concept
behind Bass Re-direction in the
television. The two controls in the Bass
Re-direction section of the signal path
allow you to route the LFE input and the
two-channel low-frequency output from
the bass-management processing to any
loudspeaker(s) connected to the
television.
As discussed elsewhere in this Guide, the
television has a logic table included in its
Bass Management and Re-direction
section that makes intelligent decisions
regarding the routing of bass to the
various loudspeakers. When the
loudspeakers in the current Speaker
Group have been chosen, the settings
for the Bass Management and the Bass
Re-direction are automatically entered
into the Advanced menus by the system.
These settings are based on
measurements of the bass capabilities of
all loudspeakers in the Bang & Olufsen
portfolio. Consequently, the bass and
LFE information will be directed to the
loudspeakers in your system with the
greatest potential to deliver low-
frequency information. These automatic
settings can be overridden simply by
entering new values in the Advanced
Settings for the Bass Management and
Bass Re-direction.
Setup: Sound: Speaker Groups: PRESETNAME: Advanced Settings: Bass Management
Balance Panning
+
Level
LF
E
1
LF
E
2
LF
E
1
LF
E
2
Bass Management Bass Redirection
Balance Level
LFE
Speaker
Subwoofer
Speaker
Balance Panning
+
Level
Speaker Speaker
Balance Level Subwoofer
Enable
Filtering
Enable
Filtering
Enable
Filtering
Enable
Filtering
Figure 9: Block diagram of the Bass Management and Bass Re-direction processing in the
television.