BowersWilkins DM 620 630 640 Owners Manual

Page 2

INTRODUCTION

The 600 Series of digital monitor loudspeakers has been developed lrom 8&W's highly successlul 500 Series and

incorporates many new leatures to give you, the user, improved perlorma

B&W maintains one 0' the linest acoustic research and development lacilities anywhere in the world. Many years
at experience in designing loudspeakers tor a variety ol applications. From the home to the recording studio,
from in-wall to in-car, has been applied to give you the best quality sound lor all applications.

Extensive use is made of computer aided design throughout the development programme, including Finite Element
Analysis - a technique to predict diaphragm behaviour - and Laser lnterterometry - used to measure actual

vibrations ol both diaphragm and cabinets In addi
devices available - the ears ol the experts - both
their music.

tion, BW has access to some ol the most sensitive measuring
musicians and others within the recording industry who know

All the systems in the Bfiw 600 Series have been designed with digitally recorded music in mind. Satislying the
extra demands of digital recording - that the loudspeakers should be able to reproduce the linest detail over a wider
dynamic range - also benelits the reproduction of analogue recordings.

The aim of this manual is to increase your knowledge of the speakers and, in doing so, give you greater enjoyment
lrom their use. Because any high quality loudspeaker is dependent both on the signals led to it and the environment
in which it is used, we have devoted sections to each of these subjects.

BRIW loudspeakers are distributed to more than 50 countries worldwide and we maintain an international network

ol carelully chosen distributors who aim to give you, the
you should have any problem which your dealer cannot resolve,

DESIGN BACKGROUND

The BitW 600 Series comprises three systems which
vary in size and therelore in their ability to reproduce the
lowest lreouencies, Power handling also increases as you
move up the range, allowmg greater maximum output
levels. There are. however, several common leatures.

The enclosures

8&W's expertise in cabinet technology lollowing the
introduction of the Matrix Series. coupled With
advanced laser measurements, allows the optimisation
ol the cabinet construction to reduce unwanted
Vibrations within the structure. All the 600 Series
cabinets are manulactured lrorn high density particle
board and internally braced. In addition, the use ol
structural plastic ballles on top ol the wooden ballles
lurther strengthens the cabinets.

The crossover netw0rl

Sophisticated computer technology at the desrgn stage
has enabled BaW to optimise each component in the
crossover networks. Computer testing during production
ensures that this optimised perlorrnance is maintained
to close tolerances on each sample.

The drive units
High-frequency

The same highlrequency unit is common to all three
systems. It uses a metal dome diaphragm to provrde
resonance-Tree pistonic motion within the audiobandr
and magnetic lluid cooling ol the voice coil to increase
power handling and reduce compression (the chilling
ol the sound at high levels when heating ol the voice
ceil reduces the sensitivity ol the unit).

Midrange/low-lrequency

DM620 A single new 200mm (8m) midrange/lowr
hequency unit with a reinlorced polypropylene
diaphragm is used. The 31mm (l Yin) voice corl is w0und
on a Kapton lormer With high-temperature epoxy
adhesives to ensure high power handling. The unit is
coupled to a 200mm (8m) passive radiator with long-
throw capability to reinlorce the lowest octaves
DM630 Two identical drive units ol similar specilrca-
tron to that used "I the DMOQO are employed in a
ported rellex enclosure. The use ol two low-lrequency
units reduces the excursion required to reproduce
the lowest lreouencres, leading to lower distortion.
Power handling is also increased. The lower unit is
progressively rolled all above 400Hz to maintain good
vertical dispersion at mid-lreouencies.

DMMO The ported reflex enclosure houses two
200mm (Bin) Cobcx diaphragm low-lrequency units

customer, the widest possible service. IT at any time

our distributors will be more than willing to assist you.

wired in parallel, crossing over to a separate midrange
unit at 3OOH1. This léOmrn (6.5m) driver uses a
sophisticated woven Kevlar diaphragm With a critical
damping layer to give the highest quality in this most
critical liequency range

UNPACKING,
INSTALLATION,
ELECTRICAL CONNECTION
AND AFTERCARE

Unpacking

We suggest that, alter unpacking your loudspeakers,

you should retain the packing in case it is necessary to

transport them at a later date. The cartons contain

(a) One 35W DMOQO/630/640 loudspeaker

(b) One accessory pack containing one alternative port
and one blanking-all plate (except DMéQO)

And in one carton only'

(c) One copy ol this user manual.

Installation

BRrW 600 Series loudspeaker systems are designed to
be lloor standing.The best balance ol sound is achieved
when the listeners' ears are thllln 1' 5° ol the releience
axis in the vertical plane (see specilications lor the
delinition ol relerence axis). This equates to a vertical
distance at t960mrri (l0.3in) at a typical listening
distance ol 3m (10h), lt it is necessary to raise the system
lrom the lloor, your dealer will be able to advise you
on suitable rigid stands.

DMo3O and DM64O are supplied With a chorce ol two
dillerent length ports and a blanking-all plate which
enable you to tailor the bass response ol the systems
(see listening room section) They are supplied Willl
the longer ol the two bayonet- lured ports litted into
the rear ol the enclosure, The level ol bass may be
increased by replacing this With the shorter porti
or reduced by littrng the blanking-oil plate

Electrical connection

All connections should be made with the ampliliei
swrtched all. Each speaker is provided With two pairs
ol gold-plated terminals at the rear ol the cabinet.
The lower pair connects the low-lrequency units and
the upper pair the high-lieQuency units (midrange and
high-lrequency units in the case ol DM640) The two
pairs ol terminals are connected together by goldplated
links. and either pair may be used to connect the system

io the power amplifier. The positive (*hed) termtnal
ol the amplilier should be connected to a positive
terminal on the loudspeaker (marked '+' With a red
band). The terminals will accept bare Wires or 4mm
(0.16m) banana plugs.

With good quality ancillary equipment. die reproduction
ol low-level detail can be improved by biwrring your
loudspeakers (separate cables Train a common power
amplilier output to each pair ol termmals), which reduces
interaction between the separate sections ol the clossA
over. A luithei tellnement is bramplihcation (each unit
led lrom a separate power amplilier) ln both cases
the terminal links should be removed alter removing the
lower terminal caps and loosening the upper ones

It is important to observe the correct polarity when
connecting a stereo pair ol loudspeakers. \X/rong
connections to one channel can result in a loss ol
bass and an inability to locus a correct stereo image.
Reversal ol the polarity to one loudspeaker will restore
the situation.

It is good practice to keep the connecting leads between
power amplilier and the loudspeakers as short as posslole
Use heavy gauge Wire to keep the DC resistance to a
minimum. pielerably below 0.20 (out and back),
Excessive inductance in the cable can lead to a lowering
ol extreme high lrequenCies, whilst excessive capacr-
lance can cause instabilily in certain power ampliliers.
Your dealer will advise you on the most suitable cable
lot your needs.

Altercare

The cabinet should be treated as any normal piece ol
lurniture. It you use an aerosol cleaner, spray onto a cloth
and keep it away liom the hem ol the loudspeaker.
especially the grille cloth and drive units. llyou need to
clean the grille, liisr remove the ham by grasping the
outer edges near the corners and gently pulling away
from the cabinet The material may then be brushed with
a normal clothes brush or similar. Please avoid touching
the drive units. especmlly the high~lrequency unit,
as damage could result.

AMPLIFIER,
CONTROL UNIT
AND SOURCE EQUIPMENT

The power amplilier

The recommended limits ol power output lor the driving
amplilier are given in the specilication However, in giving
these limits it should also be stated that ampliliei power
output requirement is an almost impossible ligure lor
the loudspeaker manulacturer to specily It will depend
entirely upon the type ol music reproduced. site at
listening room and sound level required, lt is always
better to have an amplifier with high power output,
as this allows the proper reproduction ol transients;
whereas ii the ampliliei output ls too low. clipping can
occur during high peak level transients. Apart lrom
causing audible distortion, clipping results in a relative
increase in the power led to the highlreouency unit,
with the possibility ol thermal damage,

The control unit

The control unit - although it deals With small voltages
rather than large currents as in the case ol the power
amplilier - is an equally critical part ol your listening
chain. Choose wrth care. in the knowledge that the
ultimate test for audio components is critical listening.
At BarW's research departmenl there are many dillerent
combinations ol control units, ampliliers and source
components such as analogue/CD players, tuners, etc
It is our experience that each unit (to say nothing of the
interconnecting cable) is a variable. and the linal llSlEn
ing chain is a combination ol variables which should
be carelully listened to belore making a linal choice,