Bowers & Wilkins DS8S Front Centre, Channel Surround, and 7.1 Channel Side, Channel Rear

If you are also using the speakers for movies, you should try to match the audio image to the size of the screen. That generally means that the speakers should be closer together. A good starting point is to put the speakers about 0.5m (20-in) from the edges of the screen. (figure 4)

Bookshelf or on-wall speakers should be placed at a height that brings the tweeters approximately to ear level. In the vertical plane, the dispersion narrows in the crossover region between the midrange and tweeter drive units, when both units are working together. To preserve the optimum sound balance, try to keep within ±5º of this.

Floor-standing speakers have the angle of their optimum listening window adjusted for the height of the speakers and the typical range of ear height of seated listeners.

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2.2FRONT CENTRE

If you have an acoustically transparent screen, place the speaker behind the centre of the screen. Angle it towards the listeners if the tweeter is more than 5º from ear height. (figure 5)

If you have a normal screen, place the speaker immediately above or below the screen, whichever is nearest ear height. Angle it towards the listeners if the tweeter is more than 5º from ear height. A stand with tilt adjustment is available for the HTM2D, HTM2S and HTM4S. Consult your dealer for details. (figure 6)

If you are just listening to audio, place the speakers centrally and mount bookshelf or wall mount speakers with the tweeters at ear height. (figure 7)

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2.3SURROUND

Surround speakers generally fall into two main types – those that one might describe as 'normal' speakers – so- called monopoles, where the sound comes from a set of drive units mounted on the front of the enclosure – and those that give a more diffuse sound field, such as dipoles. Each type has its advantages.

Most multi-channel music is recorded with home entertainment in mind and is monitored using monopole surround speakers, whatever the multi-channel recording format. This enables better location of side and rear images, although the formation of such images is never quite as precise as it is between the front speakers.

Most films are originally balanced for cinemas, where a large number of speakers spread around the auditorium are used to create the surround sound field. In that case there are more surround speakers than there are discrete channels of information and a less precise image is created that gives an all- enveloping effect. Dipoles and similar diffuse speakers are better at recreating this type of sound field in the home, but using fewer speakers to do it. Image positioning with these types of speaker is never as precise as it can be with monopoles. However, they do have the advantage of making it easier to balance the system for a larger listening area.

You may well receive conflicting advice from different sources on the best type of surround speaker to use. The truth is that there is no one perfect solution for all situations and the final choice for any given application will be influenced by several criteria, some of which may have a degree of conflict.

DS8S only

Within the 800 series, the DS8S is the only speaker to offer dipole operation. In fact, this specialist surround speaker has the advantage of offering a choice of both monopole and dipole operation, either via a switch located on the front baffle, behind the removable grille, or remotely, using a 12V trigger from the surround processor. You may therefore choose whichever type of operation best suits the conditions of the listening room, the size of audience and the type of programme being played. Indeed, you may even change the characteristic for different types of programme and, as the total energy into the room is the same in both modes, no recalibration of the installation is necessary when switching between them.

In monopole mode, only the two drive units on the front face operate. In dipole mode, the front tweeter is disconnected; the side firing drivers are brought into operation and the crossover frequency to the bass unit is lowered. The drive units on opposing sides are connected out of phase with one another, which creates a wedge- shaped null zone, approximately 60º wide, at right angles to the wall. If the listeners sit within this zone, they become less aware of the location of the speakers and hear more reflected sound; hence the diffuse nature of the sound field.

Use the bottom switch on the front baffle when selecting between monopole and dipole modes. In the

•position, the speaker defaults to monopole. (figure 8)

However, if a 12V signal is applied to the trigger input, internal relays switch to dipole mode. In the •• position, the speaker is always in dipole mode, whatever the trigger signal. (figure 9)

Set the direction of the positive and negative dipole lobes using the centre toggle switch marked >< on the front baffle. The stem of the switch points in the direction of the positive lobe.

For the smoothest panning of sounds between all the speakers in the installation, side speakers for all applications and rear speakers for 6.1 and 7.1 applications should have the polarity of the lobes set according to figure 10.

Application	f Go to
5.1 channel surround	2.4
6.1 and 7.1 channel side	2.5
6.1 channel rear	2.6
7.1 channel rear	2.7

2.45.1 CHANNEL SURROUND

DS8S only

If you are using the DS8S in dipole mode only, place the speakers on the side walls approximately 60cm (2 ft) above ear height and in line with the centre of the listening area. (figure 11)

If you are using the DS8S and switching between dipole and monopole modes for different applications, place the speakers on the side walls approximately 60cm (2 ft) above ear height and slightly behind the centre of the listening area, keeping the listeners within the 60º wide null zone. (figure 12)

All models except DS8S

Place the speakers approximately 120º round from front centre. The shape of the room will dictate whether they are placed on a side or rear wall. (figure 13)

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2.56.1 AND 7.1 CHANNEL SIDE

Place the speakers to the side, in line with the centre of the listening area. (figures 14 & 15)

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2.66.1 CHANNEL REAR

The rear channel of 6.1 EX recordings may be reproduced by a single speaker placed directly behind the centre of the listening area. (figure 14)

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