Bowers & Wilkins ASW600 Electrical connections, Using more than one subwoofer, Auto, Home theatre

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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