Bowers & Wilkins Loudspeaker Signature 805 - Manual (Page 5)

Should you not want to bi-wire, perhaps
during the initial set-up procedure or
because you do not want to see a
multitude of cables in the room, short
cables are provided to link both positive
and both negative speaker terminals
together.
When using the links, insert the spade into
the slot in the side of one terminal and the
crimped pin into the round side hole in the
other. There is enough clearance to insert a
spade connector from the amplifier into the
same terminal as the crimped pin.
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 can result in poor
imaging and loss of bass.
When bi-wiring, do not use the linking
cables. Take extra care with the polarity of
the connections as incorrect connection
can also impair the frequency response
through the bass-midrange crossover and,
if the links are left in place, may cause
damage to the amplifier by shorting its
output terminals.
Fine tuning
Before fine tuning, double check that all the
connections in the installation are correct
and secure.
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)
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.
Ensure the speaker stands are firm on the
floor. If you have a carpet, use carpet-
piercing spikes and adjust them to take up
any unevenness in the floor.
For the most discerning listening, remove
the cloth covered grille as described below
in the section “Aftercare”. The tweeter is
very delicate and its grille should be left in
position for protection. For this reason the
grille retaining ring is designed to provide
the optimum acoustic environment for the
unit and the response is less smooth with
the grille removed.
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 50 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 4
Ω and 8Ω loads.
The nearer the ratio is to 2:1 the better, as
it indicates a good current capability.
In order to reduce the effect the cable has
on the frequency response of the speaker
to inaudible levels, the impedance of the
cable at all frequencies (measuring both
positive and negative conductors in series)
should be kept as low as possible and
certainly below 0.1
Ω. At low frequencies,
the DC resistance of the cable is the
dominant factor and you should choose a
gauge of wire sufficient to achieve the
impedance requirements over the length of
cable you need to use. At mid and high
frequencies the inductive component of the
impedance can dominate the DC
resistance. This and other properties
influenced by the detailed construction of
the cable become important. Ask your
dealer for advice on the best cable for your
needs.
Aftercare
The cabinet surface usually only requires
dusting. If you wish to use an aerosol
cleaner, remove the grille first by gently
pulling it away from the cabinet. Spray onto
the cleaning cloth, not directly onto the
cabinet. The grille fabric may be cleaned
with a normal clothes brush whilst the grille
is detached from the cabinet.
The surface of the tweeter housing will
benefit from the use of an anti-static
cleaner. Do not attempt to remove the
tweeter grille.
Avoid touching the drive unit diaphragms,
especially the tweeter, as damage may
result.
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