Bowers & Wilkins Signature 8NT, Installation Instructions Manual

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English
INTRODUCTION
Description
The Signature 8NT is a 3-way in-wall speaker
capable of true audiophile performance.
The total design is divided into four separate
modules:
1. Wall frame and grille
2. Baffle with drive units and crossover
3. PMK (Pre/post Mount Kit)
4. Back box
Separately packing each module enables parts
to be stored safely off site until they are needed.
The first two modules are required for all
installations and so are delivered together in a
master carton. See below in this section to find
out whether you need either the PMK or the
back box for your particular application. You will
need one of them, but not both.
The speaker may be bi-wired or bi-amplified if
desired. On delivery, the two pairs of input
terminals are shorted together for single wiring by
two looped link wires on the crossover board. To
bi-wire or bi-amplify, snip these link wires at the
top of the loop. This will allow enough length for
reconnection later if desired.
Do not begin the work until you have thoroughly
read this guide.
To get the best from the speaker, it is important
that it is installed in a proper manner. We suggest
you familiarise yourself fully with these
instructions before starting any work. If there is
any point you do not understand, help and
advice is available from the appointed B&W
distributor/importer in your country.
Installation options
Warning;
The speaker drive units create stray magnetic
fields, which may affect televisions containing
conventional cathode ray picture tubes. Keep the
speaker at least 50cm (20 in) clear of such
devices. Some particularly sensitive televisions
may require further spacing.
The Signature 8NT can be installed in drywall or
solid construction in either vertical or horizontal
orientation. With existing drywall construction,
the speaker can readily be retrofitted in the
vertical orientation. However, horizontal
orientation requires cutting into vertical wall
studs, so is a major job, more akin to new
construction than normal retrofit.
The wall frame and grille
The wall frame is installed after final plastering,
but before decorating. The grille mesh and frame
may be painted as desired before the baffle and
drivers are fitted.
The baffle
The baffle contains all the working parts of the
system. Having it separate from the frame makes
it easier to fit the frame and avoids possible
damage to the drivers during decorating.
The back box
In drywall construction, the back box provides
extra sound insulation between adjacent rooms
and a safety barrier to the spread of fire between
the wall cavity and the room. If you are working
with solid walls, the back box gives a defined
working volume that extends beyond the
immediate area of the speaker itself. Any smaller
volume and the speaker will have a restricted
bass performance. For extra flexibility in
installation, for example keeping clear of other
objects in the wall, the speaker may be
positioned either in the centre of the back box, or
to one end. (Figure 16 )
The PMK
The PMK is used in drywall construction
whenever the back box is not required, whether
new construction or retrofit.
PLANNING THE SPEAKER POSITION
Overview
Consider carefully where the speakers are to be
placed in the room according to the application.
The following are guidelines but, as with any
custom installation, specific on-site conditions
may require adaptation. In particular, the position
of wall studs in drywall construction may
necessitate adjustment of the recommended
speaker position.
The speaker may be installed in either vertical or
horizontal orientation, the latter normally used for
centre channel applications to allow positioning
above or beneath the screen.
In order to maintain optimum horizontal
dispersion through the upper crossover region
and cover a spread of listeners, the centre
portion of the baffle containing the midrange and
tweeter should be rotated by 90º so that the
drivers are positioned one above the other.
The summing axis of the midrange and tweeter is
deliberately tilted 5º towards the midrange driver
and this, together with the ability to rotate of the
centre portion of the baffle, permits greater
freedom when planning the vertical position of
the speakers. If the speaker is to be mounted
with its centre above ear height, turn the sub-
baffle so that the tweeter is above the midrange.
If it is to be mounted below ear height, have the
tweeter below the midrange. Try to keep the
centre within 10º of ear height for best results.
Beyond 10º, a response dip at crossover will
begin to develop, which will make the sound
seem more recessed. Consider 15º the
maximum to allow. (Figure 1)
In horizontal orientation, the speaker will cross
normally spaced vertical drywall studs, so special
stud construction will be required to give the
necessary clearance, even if not using the back
box.
2-channel audio
Aim to have the speakers and the front centre
listener approximately at the corners of an
equilateral triangle. The listening distance will
then determine the speaker separation. If you are
restricted, err on the side of having the speakers
closer together to avoid the 'hole in the middle'
effect. (Figure 2)
The height of the speakers should ideally be
such that the centre of the baffle is within 10º of
ear height.
Multi-channel left/right front
The angle between the speakers at the listener is
normally less than for 2-channel audio. Normally
this means the speakers are within 0.5m (20 in)
of the side of the screen.
The height should be chosen so that the centre
of the baffle is as close to screen centre height
as possible, while keeping within 10º of ear
height.
Multi-channel centre front
If using an acoustically transparent projection
screen, position the speaker as close to screen
centre as possible, while keeping within 10º of
ear height. Use vertical orientation.
In all other cases, orient the speaker horizontally
and place it either immediately above or below
the screen.
Multi-channel surround
Place the speakers with the centre of the baffle
around 60cm (2 ft) above ear height to give a
more diffuse sound than from the front speakers.
For 5.1 channel systems, the two surround
speakers should be positioned an angle of
approximately 120º round from front centre.
(Figure 3) For 6.1 EX systems, the two side
speakers should be more forward than this,
almost in line with the listeners. One speaker
should be placed on the rear wall directly in line
with the centre of the listening area. Alternatively
two rear speakers may be used side by side, one
either side of a stud in drywall construction.
(Figure 4) For 7.1 systems, the two rear speakers
should be further apart. A good guideline is for
them to have an angular spread of about 40º to
the listeners. (Figure 5)
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