Bowers & Wilkins ASW 12CM Speaker User Manual

ith the switch set to Auto, the subwoofer will
initially become fully active and the indicator will glow
reen. After about 5 minutes without an input signal,
the subwoofer will automatically enter “sleep” mode.
he indicator will glow red. When an input signal is
etected, the subwoofer will automatically become
active and the indicator will glow green. The
ubwoofer will return to sleep after about 5 minutes
ith no input signal.
Audio-visual processors incorporating an “automatic”
set up procedure may be “confused” by subwoofers
ith an auto switch-on/sleep function. A potentially
damaging fault condition can arise. Subwoofers are
best left switched on and fully active during set up if
such a pro
cessor is used.
Standby: With the switch set to Standby the
subwoofer will become active when 12V is applied to
the Trigger Input (Item 10 in Figure 1). Zero volts at the
input will return the subwoofer to sleep. The indicator
will glow green when the subwoofer is active and red
when the subwoofer is in sleep.
Setting The Subwoofer Controls
There are 7 controls to consider:
The VOLUME (LINE) control (Item 3 in Figure 1)
The VOLUME (SPEAKER) control (Item 4 in
Figure 1)
The LOW-PASS FREQ (frequency) control (Item 5
in Figure 1)
The LOW-PASS FILTER switch (Item 6 in Figure 1)
Note: This applies only to the LINE input. The filter
is always in circuit with the SPEAKER LEVEL
The BASS Extension switch (Item 7 in Figure 1)
The EQ (equalisation) switch (Item 8 in Figure 1)
The PHASE switch (Item 9 in Figure 1)
The appropriate settings depend on the equipment
used with the subwoofer and the modes of
connection. If using more than one subwoofer, ensure
the controls on each one are set the same.
controls only operate on their respective line and volume
inputs. An unused volume control is best set to Min.
Home Theatre Settings
Set the VOLUME (LINE or SPEAKER) control initially to
the 9 o’clock position.
Set the LOW-PASS FILTER switch to OUT.
Set the EQ switch initially to position A.
Set the PHASE switch initially to 0
Set the LOW-PASS FREQ (frequency) control to 140 if
the speaker level inputs are used. The setting is
irrelevant if the line level inputs are used.
See the “Fine T
uning” section for mor
The subwoofer is not a THX
licensed component, but
may be used with a THX
oller if desir
ed. If a
controller is used, ensure that the subwoofer
unction is enabled. This incorporates all the filtering
and level setting required for the subwoofer in all
odes. For level calibration, the internal test noise and
channel level controls in the THX
controller should be
sed. In all cases the levels should be set to obtain
5dB SPL (C-weighted) at the listening position from
the controller’s internal noise test signal.
With other processors, configure the front and
urround speakers to “large” or “small” as appropriate
before setting the levels. Use the internal noise test
signal and volume controls of the processor to set the
evels of all the speakers. Only change the VOLUME
control on the subwoofer if there is not enough range
in the processor to achieve the correct levels.
Inexpensive sound level meters are
readily available
rom electronics stores and can be used to calibrate
the levels. Refer to your processor manual for further
details on how to set the levels.
2-channel Audio Settings
Set the VOLUME (LINE or SPEAKER) control initially to
the 9 o’clock position.
Set the LOW-PASS FILTER switch to IN.
Set the EQ switch initially to position A.
Set the PHASE switch initially to 0°.
Set the LOW-PASS FREQ control to match the -6dB
low frequency cut-off frequency of the satellite
speakers. Note: Both -3dB and -6dB figures can be
found in the specification of each B&W speaker
model. If the satellite speaker manufacturer quotes
only a -3dB frequency, the optimum setting for the
LOW-PASS FREQ control should be between 0.6 and
0.9 times that figure. The more gradual the low
frequency roll-off of the satellite speakers, the lower
the frequency should be set.
See the Fine Tuning section for more.
Home Theatre
In home theatre systems, the subwoofer (LFE) signal is
a separate channel rather than an extension of the
signal to the satellite speakers. The LOW-PASS
FILTER is switched out (or set to maximum), because
the processor provides all the filtering for any speakers
set to “small”. However, the position of the PHASE
switch must still be assessed. Normally the phase will
be set to 0°, but if the subwoofer is positioned at a
distance significantly different from the other speakers,
or the power amplifier driving the other speakers
happens to invert the signal, the 180
° position may be
preferable. Listen with the switch in both positions and
choose the one that gives the fullest sound. If there is
little difference, leave the switch at 0°.
Surround sound processors normally have a calibrated
noise signal that can be used to set the relative levels
of all the speakers, making the task somewhat mor
straightforward than for 2 channel audio. However, do
not be afraid to alter the settings to your personal
preference. It is all too easy to get carried away with
the capabilities of the subwoofer
, especially with some
special low-frequency effects. Often a more realistic
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