Bowers & Wilkins Signature 800 Manuel D'utilisation page 5

4mm banana plugs, use the smaller
diameter section of the screw caps, which
loosens or tightens a collet round the plug.
In all cases, make sure both sections are
screwed down in use to prevent rattling.
Important safety notice:
In certain countries, notably those in
Europe, the use of 4mm banana plugs is
considered a potential safety hazard,
because they may be inserted into the
holes of unshuttered mains supply sockets.
In order to comply with European
CENELEC safety regulations, the 4mm
holes in the ends of the terminals are
blocked by plastic pins. Do not remove the
pins if you are using the product where
these conditions apply.
There are 2 pairs of terminals at the back of
the speaker. The outermost (LF) pair feed
the bass drivers and the innermost (MF/HF)
pair feed the midrange and tweeter. This
separation of the inputs to each section of
the speaker allows a choice of connection
methods.
On delivery, both positive and both negative
terminals are connected together with high-
quality links for use with single 2-core
cable. If you wish to use single cable
connection, the links must be left in place.
Because high frequency signals are more
readily degraded by contact connections,
we recommend you connect the cable
directly to the innermost (MF/HF) terminals
(figure 3a). Even if you finally intend to use
a more complex connection method, single
cable connection aids free movement of the
speakers during initial setting up. There is
enough clearance to fit a spade connector
on top of a link.
Separation of the signal paths to each
section of the speaker can improve imaging
and the resolution of low-level detail and
allows the user to optimise the cable to the
frequency range of use. Bi-wiring involves
the use of two separate 2-core cables from
the same amplifier, one to each pair of
terminals on the speaker. Bi-amplification
involves the use of two separate power
amplifier channels for each speaker. In both
cases, the links should be removed from
the speaker terminals (figure 3b).
Ensure each positive terminal on the
speaker (coloured red) is connected to the
positive output terminal of the amplifier and
negative (coloured black) to negative.
Incorrect connection may result in
impairment of frequency response, poor
imaging and loss of bass.
If using bi-amplification, ensure that each
amplifier channel has the same gain,
otherwise you will change the balance of
the speaker. Check the absolute polarity.
Some amplifiers invert the signal, and a
mixture of different types may cause a dip
in the overall response. If you have a
mixture of inverting and non-inverting
amplifiers, reverse the polarity of the
connections from any inverting amplifier to
the speaker. Bear in mind that, even though
midrange and, even more so, tweeter
drivers can (and only need to) handle less
continuous power than bass drivers, the
amplifier feeding them needs to have an
adequate voltage swing in order to supply
2
the short–term high–frequency peaks in
music without distortion. A high voltage
capability implies high power, so it is not
particularly desirable to have a lower power
amplifier feeding the midrange and tweeter
than is used for the bass drivers.
Fine tuning
Before fine tuning, double check that all the
connections in the installation are correct
and secure.
Positioning the speakers:
Moving the speakers further from the walls
will reduce the general level of bass. Space
behind the speakers also helps to create an
impression of depth. Conversely, moving
the speakers closer to the walls will
increase the level of bass.
If the bass is uneven with frequency it is
usually due to the excitation of resonance
modes in the room.
Even small changes in the position of the
speakers or the listeners can have a
profound effect on how these resonances
affect the sound. Try mounting the
speakers along a different wall. Even
moving large pieces of furniture can have
an effect.
If the central image is poor, try moving the
speakers closer together or toeing them in
so they point at or just in front of the
listeners. (figure 4)
Room acoustics:
If the sound is too harsh, increase the
amount of soft furnishing in the room (for
example use heavier curtains), or reduce it
if the sound is dull and lifeless.
Test for flutter echoes by clapping your
hands and listening for rapid repetitions.
Reduce them by the use of irregular
shaped surfaces such as bookshelves and
large pieces of furniture.
If you still suffer poor results due to the
acoustics of the listening room, consult
your dealer about more substantial acoustic
treatment.
Fitting the alternative feet: (figure 5)
Most speakers perform best, particularly in
terms of bass attack and timing, given a
firm mechanical foundation. Unless you
wish to move the speakers on a regular
basis, we recommend you replace the ball
glides on the underside of the plinth with
the alternative feet supplied.
Switch off the equipment and disconnect
the cables from the terminals.
• Use at least two people to manoeuvre
the speaker. Remove rings and
bracelets to avoid scratching the
speaker surfaces.
• Lay the speaker on its back, resting on
the polystyrene packing cradle to
protect it from the floor.
• Replace the ball glides with the conical
foot receptacles, using the Allen key
provided.
• If you have a carpeted floor, fully screw
in the spike foot tips, otherwise use the
flat foot pads.
• Return the speaker to the upright
position.
• If the speaker rocks on two of the feet,
unscrew the other two feet equally,
using the bar provided, until the
speaker stands firmly on the floor.
If the seating position is particularly low, the
speaker may be tilted forward. The spike
may be extended to a maximum of 45mm
(1.75in) from the foot receptacles. Screw
the front two feet in as far as possible and
extend the rear feet evenly to suit. Adjust
the rear feet to eliminate rocking and
tighten the lock nuts.
Fitting the midrange grille:
A grille is supplied in the accessory pack to
cover the midrange drive unit if desired.
Fitting the grille also requires the centre
bullet of the drive unit to be replaced by the
alternative version with a hole in the tip
from the accessory pack.To fit the
alternative centre bullet, simply unscrew the
fitted part and screw in the replacement,
taking care not to damage the voice coil
former. Hand tighten only.
Running-in period
The performance of the speaker will change
subtly during the initial listening period. If
the speaker has been stored in a cold
environment, the damping compounds and
suspension materials of the drive units will
take some time to recover their correct
mechanical properties. The drive unit
suspensions will also loosen up during the
first hours of use. The time taken for the
speaker to achieve its intended
performance will vary depending on
previous storage conditions and how it is
used. As a guide, allow up to a week for
the temperature effects to stabilise and 60
hours of average use for the mechanical
parts to attain their intended design
characteristics.
Ancillary equipment
Speakers of this ability deserve signals of
the highest quality. Choose your electronic
equipment and interconnecting cables with
care. We can give guidance on what to
look for when choosing ancillary
equipment, but cannot recommend specific
items. The standards of such products are
improving all the time and your dealer will
be able to demonstrate a variety of suitable
up-to-date products.
In the specification we recommend a range
of amplifier powers. The higher figure is
defined by the power handling capability of
the speaker. When calculating the power
handling, it is assumed that the amplifier is
not run into clipping, which distorts the
frequency power spectrum of the signal,
and that the signal is normal programme
material. Test tones from oscillators and the
like are not applicable. The lower figure is
the minimum we consider necessary to
achieve reasonable listening levels without
audible distortion in the smaller room (less
than 60 m 3 or 2000 cu ft). The higher the
power you use, the less likely you are to
experience amplifier clipping. You can often
tell how good an amplifier is at driving
complex speaker loads by looking at its
power rating into both 4Ω and 8Ω loads.