Bowers & Wilkins ASW10CM S2 Manual page 9

5. Fine Tuning
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 more
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
portrayal, and one more satisfying in the long term, is
to be had by setting the subwoofer level lower than the
standard calibration level.
2-channel Audio
Set the system up in the preferred position and play
some programme with a steady bass content.
The optimum settings of the PHASE switch and the
LOW-PASS FREQ control are inter-related and also
dependent on the low-frequency cut-off characteristic
of the satellite speakers. However, the settings
recommended above for the LOW PASS FREQ control
and PHASE switch have been chosen to integrate well
with most satellite speaker bass alignments.
Using the initial settings, first check the setting of
the PHASE switch. Choose the option that gives the
fullest sound. Normally the recommended option will
be optimum, but may not be in certain circumstances.
These may be that the power amplifiers feeding
the satellite speakers invert the signal or that the
subwoofer is not placed close to the satellite speakers.
Next, adjust the VOLUME (LINE or SPEAKER) of the
subwoofer relative to the satellite systems to your
liking. Use a wide variety of programme material to get
an average setting. A setting that sounds impressive on
one piece may sound overpowering on another. Listen
at a realistic volume level as the perception of musical
balance varies with sound level.
Finally, adjust the LOW-PASS FREQ control to give
the smoothest transition between the subwoofer and
satellite speakers.
All Applications
The BASS EXTENSION switch offers three options
of subwoofer bass extension. Position A gives the
greatest extension and position C gives the least
extension. Position B provides a compromise setting.
If the system is to be used at very high volume levels
or in a large listening room, restricting the bass
extension by selecting either B or C may help
ensure that the subwoofer is not asked to exceed
its performance limits. In most situations the BASS
EXTENSION switch should be left in position A.
The EQ switch alters the subwoofer bass roll-off
alignment. The bass you hear is a combination of the
subwoofer plus the effects of the room and you should
choose the position that best complements your room
and the location of the subwoofer. Position A gives a
"drier" alignment, more suited to placing the subwoofer
in a corner or compensating for a resonant room.
Position B is suited to a less resonant room acoustic
and use away from a corner.
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