Bowers & Wilkins DS8S - Manual (Page 8)

5
The ear is at its most sensitive in the
midrange, so we recommend that, when
single wiring, you connect the cable from
the amplifier to the terminals that directly
feed the midrange driver.
Bi-amplification goes a stage further and
involves the use of two separate power
amplifier channels for each speaker. It is
not the same as having a fully active
system, because the speaker's internal
passive crossover is still used.
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 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 powered amplifier feeding the
midrange and tweeter than is used for
bass drivers.
Model f Go to
800D 4.2
All other models (not DS8S) Continue
On delivery, the two pairs of terminals are
electrically separate from one another
ready for bi-wiring. (figure 32)
For single wiring, short cables are
provided to link both positive and both
negative terminals together. Each cable
carries a spade connector at one end
and a 4mm banana plug at the other.
When single wiring, connect the cable
from the amplifier to the lower terminals
on 2-way systems (805S, HTM4S,
SCMS) and the upper terminals on
3-way systems.
On these terminals, use the opposite
type of connector on the link cables to
what you have terminating your main
cable. For example, if your main cable
terminates in spade connectors or bare
wires, use the banana plug end of the
link cables in the same terminals.
(figure 33)
f Go to section 5.
4.2 800D
On delivery, both positive and both
negative terminals are connected
together by link plates.
When single wiring, leave these links in
position and connect the cable from the
amplifier to the centremost pair of
terminals. (figure 34)
When bi-wiring or bi-amplifying, remove
the links after loosening the lower, larger
diameter terminal caps. (figure 35)
The 4mm hole in the end of the terminal
post features a collet that may be
tightened around a banana plug using
the upper, smaller diameter terminal cap.
f Go to section 5.
4.3 DS8S
In addition to the normal speaker
terminals, there is an additional pair of
screw terminals to operate an internal
12V relay that switches the speaker
between monopole and dipole modes
from a remote trigger. (figure 36)
You cannot use this facility if:
a Your processor does not feature a
12V trigger at all.
b Your processor only offers a simple
trigger that outputs a 12V signal when
the unit is switched on. This can only
be used to switch other equipment on
and off at the same time.
Some of the most expensive processors
allow you to assign a trigger to the type
of programme being played. They
recognise information on the disc that
distinguishes between movies and multi-
channel music. Others allow you to
assign triggers to different inputs; so if,
for example, you use a multi-channel
SACD or DVD-A player for music and a
separate DVD player for movies, you can
set up a trigger accordingly.
The relay in the speaker needs a certain
amount of current to operate, so check
the specification of your processor first
before proceeding. You will need to draw
45mA for each speaker you want to
switch.
The relay in the speaker only works when
the manual switch is set to the monopole
(•) position. If there is no voltage to the
trigger input, the speaker stays
monopole. If a 12V DC signal is present,
the relay overrides the manual monopole
setting and switches the speaker to
dipole mode. If you have the switch set
to the dipole (••) position, the trigger
feature will not work.
f Continue to section 5.
5 FINE TUNING
Before fine tuning, double check that all
the connections in the installation are
correct and secure.
Floor- and stand-mount speakers
only
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.
803D, 803S, 804S, 805S, HTM1D,
HTM2D, HTM4S, SCMS only
These vented-box systems are
supplied with foam plugs fitted in the
ports. Normally, the speakers should
be used with these plugs removed for
maximum bass output, but if the bass
is too heavy due to room effects and
you cannot move the speakers further
from the walls, refit the plugs to reduce
the bass output. (figure 37)
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
positioning the speakers along a different
wall. Even moving large pieces of
furniture can have an effect.
For the most discerning listening, remove
bass and midrange grilles as
described in section 8 –
Aftercare.
Tweeter diaphragms are very
delicate and easily damaged. The
tweeter grilles are held in place with
magnetism and any mishandling of the
grille close to the tweeter may result in
the grille being attracted into the tweeter
diaphragm. For these reasons, we
recommend that you leave tweeter grilles
in place.
800D, 801D, 802D, HTM1D only
If you use these systems without the
midrange grille, replace the plastic
centre plug of the midrange drive unit
with the solid aluminium plug in the
accessory pack. Simply unscrew the
fitted plug and screw in the
replacement. Hand tighten only.
(figure 38)
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.