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generally gives inferior imaging, but may be
an acceptable compromise if domestic
considerations dictate.
As with all speakers, the proximity of room
boundaries affects the sound. Bass is
generally increased as more surfaces come
into close proximity with the speakers.
Unlike full-range speakers, however, you
can always restore the correct overall
system balance by adjusting the volume
level of the subwoofer. The more boost you
get from the room, the less hard the
speaker has to work; but there is a down
side. Corner positions often excite more
low-frequency room resonances, making
the bass more uneven with frequency.
There is no substitute for experiment as all
rooms behave differently, so try the
subwoofer in a variety of positions before
making a final decision. A piece of music
with a bass line ascending or descending
the musical scale is useful for assessing the
smoothness of the bass response. Listen
for exaggerated or quiet notes. Having a
separate subwoofer does enable you to
optimise for room resonances
independently from siting the satellite
speakers for best imaging.
If the subwoofer is to be used in a confined
space (eg in custom furniture), the space
must be ventilated to allow sufficient air to
circulate and cool the unit. Ask your dealer
for advice.
The subwoofer is supplied with four spike
feet. The spikes pierce through carpet pile,
giving a firm support directly to the floor
surface without crushing the pile.
If the unit is to be placed on a vulnerable
surface, such as a wooden floor, either
place a protective disc under each spike or
fit the four rubber feet in place of the
spikes.
When fitting either the rubber feet or the
spike feet, first screw the lock nuts fully
onto the thread and then screw the feet
fully onto the threaded inserts in the base
of the cabinet. If the unit rocks, loosen the
relevant two opposing feet until the support
is firm, then re-tighten the lock nuts to the
inserts.
Electrical connections
Disconnect all sound system equipment
from the power supply until the signal
connections have been made and checked.
This avoids the risk of damage whilst
connections are made or broken.
The subwoofer will input and output both
line-level signals via the RCA Phono
sockets and speaker level signals via the
binding posts located on the back panel.
Use the following guide to select the
correct wiring method for your installation:
Application: Home Theatre
Processor with separate power amplifiers
feeding one or more subwoofers – fig 3
Processor with integrated power amplifiers
feeding one or more subwoofers:
– with line level subwoofer output – fig 4
– with speaker level subwoofer output –
fig 5
Application: 2-channel audio
Separate pre- & power amplifiers:
– Full range signal to satellite speakers and:
– One subwoofer – fig 6
– Two subwoofers – fig 7
– High-pass signal to satellite speakers
and:
– One subwoofer – fig 8
– Two subwoofers – fig 9
Integrated pre- & power amplifier:
– Full range signal to satellite speakers and:
– One subwoofer – fig 10
– Two subwoofers – fig 11
– High-pass signal to satellite speakers
and:
– One subwoofer – fig 12
– Two subwoofers – fig 13
Using more than one subwoofer
Using more than one unit in a single
installation can improve performance in the
following ways:
• Maintain stereo separation to the
lowest frequencies.
• Cope with larger listening rooms.
• Enable greater maximum sound output
– often useful for effectively
reproducing special effects in Home
Theatre applications.
• Smooth out the effects of low-
frequency room resonances.
If you are using two subwoofers for 2-
channel audio, stereo separation is
improved if each channel has its own
subwoofer, providing each one is placed
close to the relevant satellite speaker. Only
use the mono connection of figure 8 if you
cannot place each subwoofer close to its
satellite speaker.
Double-check the connections
ENSURE THAT THE VOLTAGE INDICATED
ON THE AMPLIFIER PANEL MATCHES
THAT OF THE POWER SUPPLY.
Before auditioning the sound quality of your
new installation and fine-tuning it, double-
check the connections. All too often, users
complain that they cannot get a decent
sound however they set the controls, only
to discover something has been wrongly
connected. Make sure that:
• The phasing is correct – there should
be no positive to negative connections
to the satellite speakers. If something
is out of phase you may get a fuzzy
sound with an imprecise and floating
image, a lack of bass or a combination
of the two.
• There are no left to right mix-ups – this
can result, for example, in the
orchestra being the wrong way round
or, more disastrously, sounds on your
Home Theatre going in the opposite
direction to the action on the screen.
Switching on and off
We recommend that you switch the
subwoofer on before any power amplifiers
receiving signals from the subwoofer.
Similarly, when switching off, switch the
subwoofer off last.
The MODE On/Auto switch (8) and
indicator light (9) operate as follows:
On:
With the switch in this position, the
amplifier remains permanently fully active,
and the light glows green.
Auto:
On first switching on the subwoofer while
set to Auto, the amplifier becomes fully
active and the light (9) glows green. After a
period of about 5 minutes without an input
signal, the amplifier automatically reverts to
standby mode, and the light glows red.
When an input signal is detected, the
amplifier automatically becomes fully active
and the light glows green.
Setting the controls
There are 5 controls to consider:
• The VOLUME control (10)
• The LOW-PASS FILTER frequency
control (5)
• The LOW-PASS FILTER switch (7)
• The PHASE switch (6)
• The EQ (equalisation) switch (4)
The optimum settings depend on the other
equipment used with the subwoofer. If
using more than one subwoofer, ensure the
controls on each one are set the same.
Home theatre
The subwoofer is not a THX® licensed
component, but may be used with a THX®
controller if desired.
• Set the VOLUME 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°.
• The setting of the LOW-PASS FILTER
frequency control is irrelevant.
See also the section "Fine tuning".
If you have a THX® controller, ensure that
the subwoofer function is enabled. When
so configured it incorporates all the filtering
and level setting required for the subwoofer
in all modes. For level calibration, the
internal test noise and channel level
controls in the THX® controller should be
used. In all cases the levels should be set
to obtain 75dB SPL (C-weighted) at the
listening position from the controller’s
internal noise test signal.
With other processors, configure the front
and surround 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
levels of all the speakers. Only change the
VOLUME control on the subwoofer if there
is not enough range in the processor to
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