Bowers & Wilkins AS2 Electrical connections, Using more than one subwoofer, Double-check the connections, Switching on and off, Setting the controls

them. If you use two subwoofers, it is best

to put one near the left and one near the

right speaker.

Placing the subwoofer behind the listeners,

even in surround sound installations,

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 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(figure 4)

Connect the subwoofer LINE IN socket (2)

to the line-level output of the processor

marked LFE or SUBWOOFER, using a

suitable coaxial interconnect cable. If using

more than one subwoofer, daisy chain them

together by connecting the LINK OUT

socket (3) of the first to the LINE IN socket

(2) of the next.

Application: 2-channel audio

For 2-channel operation, use speaker level

rather than line level connections. The

subwoofer presents a high impedance load

to the stereo power amplifier and takes

very little current, so may be connected in

parallel with the main speakers with no

adverse effects.

Using one subwoofer(figure 5)

The left and right channels are both

connected and summed in the subwoofer

amplifier.

Using two subwoofers(figure 6)

If one subwoofer can be placed close to the

left speaker and the other close to the right

speaker, stereo separation is best

maintained by connecting each subwoofer

to a separate output channel of the amplifier.

If the subwoofers cannot be placed close

to the main speakers, better results may be

obtained by feeding the left and right

channels to both subwoofers, connecting

both subwoofers as shown in figure 5 and

described above in the section “Using one

subwoofer”.

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.

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 after any equipment feeding

signals to it. Similarly, when switching off,

switch the subwoofer off first.

The MODE standby/auto/on switch (7) does

not isolate the amplifier completely from the

power supply. It maintains a low-power

input to an auxiliary sensing circuit.

The switch (7) operates as follows:

O On:

With the switch in this position, the

amplifier remains permanently on, and the

light glows green.

A Auto:

On first switching the subwoofer to Auto,

the amplifier goes into standby mode, and

the light glows red. When an input signal is

detected, the amplifier automatically

becomes fully active and the light 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.

s Standby:

In this position, the amplifier is in

permanent standby, and the light glows

red. If, when set to Auto, the subwoofer

should repeatedly go into standby mode

when playing programme via the LINE IN

socket, try reducing the volume setting on

the subwoofer and restoring the balance by

increasing the subwoofer output of the

processor.

If the subwoofer is to be out of use for an

extended period of time, we recommend

you isolate it from the power supply by

removing the plug from the power socket.

Setting the controls

There are 4 controls to consider:

• The volume control (VOL) (11)

• The low-pass frequency

control (Hz) (10)

• The PHASE switch (9)

• The EQ (equalisation) switch (8)

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.

Use with home theatre decoders

The B&W Active Subwoofer is not a THX®

licensed component, but may be used with

a THX® controller if desired.

• Set the volume control initially to the

12 o’clock (detent) position.

• Set the EQ switch initially to position i.

• Set the PHASE switch initially to +.

• The setting of the low-pass frequency

control is irrelevant.