KEF Audio 208, 209 User Manual

Applicable for Reference Series Models 209 and 208, model numbers SP3557 and SP3556

WARNING

TO REDUCE THE RISK OF FIRE OR ELECTRICAL SHOCK, DO NOT EXPOSE

THIS APPLIANCE TO RAIN OR MOISTURE

Explanation of Graphical Symbols

CAUTION

RISK OF

ELECTRIC SHOCK

DO NOT OPEN

CAUTION: TO REDUCE THE RISK

OF ELECTRIC SHOCK, DO NOT

REMOVE COVER (OR BACK).

NO USER-SERVICEABLE PARTS

INSIDE. REFER SERVICING TO

QUALIFIED SERVICE PERSONNEL

• A combined mains power input lead and country specific mains plug is provided.

• Check before connecting to your local mains supply that the local supply voltage is the same as that marked
on the rear panel. If it is not, check with your supplier before proceeding.

WARNING:

Due to the mains switch being located on the rear panel, the apparatus must be located in an open area without
anything obstructing access to the mains switch.
Because this is a Class 1 product it must be connected to the protective earth connection.
The mains plug or power connector must be readily accessible to allow the power to be removed from this product.

The lightning flash with arrowhead symbol, within an
equilateral triangle, is intended to alert the user to the
presence of uninsulated “dangerous voltage” within
the product’s enclosure that may be of a sufficient magnitude
to constitute a risk of electrical shock to persons.

The exclamation mark within an equilateral triangle is
intended to alert the user to the presence of important
operating and maintenance (servicing) instructions in the
literature accompanying the appliance.

CAUTION:

• To prevent electric shock, do not open the rear panel.

• This product is for indoor use only.

• This electrical apparatus should not be exposed to dripping or splashing and care should be taken not
to place objects for holding liquids, such as a vase or drinks container, on top of this apparatus.

•

Do not install near any heat source such as radiators, stoves or other appliances that produce heat.

• Ensure that the power plug and cord are correct for your sockets.
Do not use if they show any signs of damage.

This device complies with Part 15 of the FCC Rules. Operation is subject to the following conditions:
(1) this device does not cause harmful interference, and (2) this device will accept any interference
received, including interference that may cause undesired operation.

The manufacturer is not responsible for any radio or TV interference caused by unauthorised
modifications to this equipment. Such modifications could void the user authority to operate
the equipment.

NOTE:

This equipment has been tested and found to comply with the limits for a Class B digital device, pursuant to
Part 15 of the FCC Rules. These limits are designed to provide reasonable protection against harmful
interference in a residential installation. This equipment generates, uses and can radiate radio frequency
energy and, if not installed and used in accordance with the instructions, may cause detrimental interference
to radio communications.

However, there is no guarantee that interference will not occur in a particular installation. If this equipment does
cause harmful interference to radio or television reception, which can be determined by turning the equipment
off and on, the user is encouraged to try to correct the interference by one of the following measures:

• Reorient or relocate the receiving antenna.

• Increase the separation between the equipment and receiver.

• Connect the equipment into an outlet on a circuit different from that to which the receiver is needed.

• Consult the dealer or an experienced radio/TV technician for help.

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Part No.: K290225E

Issue 1: December 2007

Important Safety Instructions Important Information

Please take heed of the following before using the KEF Reference Series Subwoofer.
Note also that the word “appliance” shall refer to the KEF Reference Series Model 209/
Model 208 Subwoofer, or any part of it.

1. Read Instructions -

appliance is operated.

2. Retain Instructions - The Safety and Operating Instructions should be retained for
future reference.

3. Heed Warnings - All warnings on the appliance and in the Operating Instructions should be
adhered to.

4. Follow Instructions - All Operating and Use Instructions should be followed.

5.

Water and Moisture - The appliance should not be used in or near water - for example, near a

bathtub, washbowl, kitchen sink, laundry tub, in a wet basement, or near a swimming pool, and the like.
This apparatus should only be used in moderate climates.

6. Ventilation - The appliance should be situated so that its location or position does no interfere
with its proper ventilation. The rear panel should be at least
ventilation should not be impeded by covering the ventilation openings with items such as table
cloths, curtains etc.

7. Heat - The appliance should be situated away from heat sources such as radiators, heat registers,
stoves or other appliances (including amplifiers) that produce heat. No naked flame sources such as
lighted candles should be placed on the apparatus.

8. Power Sources - The appliance should be connected to a power supply only of the type
described in the operating instructions or as marked on the appliance.

9. Grounding or Polarisation - The precautions should be taken so that the grounding or
polarisation means of an appliance are not defeated.

10. Power-cord Protection - Power supply cords should be routed so that they are not likely to be
walked on or pinched by items placed upon or against them, paying particular attention to cords at
plugs, convenience receptacles and the point where they exit from the appliance.

11. Cleaning - The appliance should be cleaned only as recommended by the manufacturer.

12. Non-use Periods - The power cord of the appliance should be unplugged from the outlet during

lightening storms or when left unused for a long period of time.

13. Damage Requiring Service - The appliance should be serviced by qualified service
personnel when:

a) The power supply cord or the plug has been damaged;
b) Objects have fallen or liquid has been spilled on the appliance; or
c) The appliance has been exposed to rain; or

d) The appliance does not appear to operate normally or exhibits a marked change in

performance;

e) The appliance has been dropped or the enclosure damaged.

14. Servicing - The user shall not attempt to service the appliance beyond that described in the
Operating Instructions. All other servicing should be referred to qualified service personnel.

15. Only use attachments/accessories specified by the manufacturer.

16. Use only with a cart, stand. tripod, bracket, or table specified by the manufacturer,

or sold with the apparatus. When the cart is used, use caution when moving the
cart/apparatus combination to avoid injury.

All the Safety and Operating Instructions should be read before the

15cm from any object. The

or

or

Thank you for purchasing this KEF Reference
Series subwoofer. It has been designed to faithfully
reproduce high quality sound over many years of
use. Please take a little time to read these
instructions prior to use.

Your KEF Reference subwoofer is extremely
heavy. Installed correctly on a smooth, level
surface, it should be entirely safe to listen to and
to live with.

However, if you have small children, large pets, the
infirm, uneven flooring or unusually thick carpeting
in your home, then correct adjustment of the foot
assemblies is imperative for safe, stable operation
is to be achieved.

1. Read this manual carefully, especially the safety
information, before attempting to assemble
and operate the system. Please take heed of
the following safety instructions before using
the appliance. The word “appliance” shall refer
to the KEF Reference Series Model 209/Model
208 subwoofer, or any part of it. The Safety
and Operating Instructions should be retained
for future reference. All warnings on the
appliance and in the Operating Instructions
should be adhered to.

2. All Operating and Use Instructions should be
followed. Follow the unpacking procedure
shown. Please note that lifting the heavy KEF
Reference Series Model 209/Model 208
subwoofer will require two able-bodied
persons, or consult your dealer for assistance.

3. Make sure the feet are correctly fitted before
the subwoofer is lifted to the correct position.
If the subwoofer is to be used on delicate
wooden flooring please use the supplied
protective cups which fit under the feet.

4. Trailing cables are dangerous. Ensure that all
cables are secure and tidy. The appliance
should be connected to a power supply only of
the type as marked on the appliance.
Precautions should be taken so that the
grounding and polarisation of the mains
connection are not defeated.

The power supply cord should be routed so
that they are not likely to be walked on or
pinched by items placed upon or against it.

5. When stripping cables use only tools designed
specifically for the purpose ie: correct wire
cutters or cable strippers. Do not attempt to
strip cables with a knife as this could result in
serious injury.

6. The appliance should not be used in or near
water or moisture - for example, near a
bathtub, washbowl, kitchen sink, laundry tub,
in a wet basement, or near a swimming pool,
and the like.

7. The appliance should be situated so that its
location or position does no interfere with its
proper ventilation. The rear panel should be at
least 15cm from any object. The subwoofer
should be situated away from heat sources
such as radiators, heat registers, stoves or
other appliances (including other amplifiers)
that produce heat.

8. The appliance should be cleaned only as
recommended in this manual.

9. The appliance should only be serviced by
qualified service personnel. The subwoofer
should be serviced if :

a) The power supply cord or the plug has been

damaged; or

b) Objects have fallen or liquid has been spilled

on the appliance; or

c) The appliance has been exposed to rain or

moisture; or

d) The appliance does not appear to operate

normally or exhibits a marked change in
performance; or

e) The appliance has been dropped or the

enclosure damaged.

17. The mains plug is used as the disconnect device. It shall remain readily operable and should not be
obstructed during intended use. To completely disconnect the apparatus from supply mains, the
plug must be removed from the mains socket outlet completely.

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3

General Care of your System

1. Avoid temperature extremes.

2. Avoid damp.

Contents

Important Safety Instructions and Information 1

General Care of Your System 4

Contents 5

3. Avoid direct sunlight.

4. Clean with the KEF cloth provided.

5. Do not use spirit based cleaners.

If you are at all uncertain about setting up, operating or caring for your system
your dealer will be pleased to assist you.

Correct

Positive/RED

Reference Model 209

Introduction and Overview 7

ACE Technology 8
Room Correction 9

Installation and Operation 10

Unpacking, Handling and Aftercare 10
Accessories 11
Adjusting the Feet and/or Spikes 12
Subwoofer Positioning 13
Rear Panel Information 14
Remote Control and Control Functionality 16
Connections, Setup and Fine tuning 18

- connection diagrams

- movie only setup through the LFE input

- music only setup through the Left/Right input

- combined movie and music setup

- connecting to the speaker inputs (high level)
Using the Preset Equalization options 22
Using the Room Correction facility 23
Grille 24

Warranty 24

Service Information 24

Specifications 25

Wrong

Adjustment

Caution/Warning

Electrical Warning

Negative/BLACK

Switch off appliance

Option

Read

Reference Model 208

Introduction and Overview 27
Installation and Operation 28

Unpacking, Handling 28
Accessories 29
Adjusting the Feet 30
Subwoofer Positioning 31
Rear Panel Information 32
Control Functionality 34
Connections, Setup and Fine tuning 36

- connection diagrams

- movie only setup through the LFE input

- music only setup through the Left/Right input

- combined movie and music setup

- connecting to the speaker inputs (high level)
Grille 40

Warranty 40

Service Information 40

Specifications 41

KEF Heritage 43

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IntroductionIntroduction and Overview

The KEF Reference Series 209 subwoofer is a ‘state
of the art’ subwoofer for use in the very best home
theatre and stereo systems. Every component is
critically designed to give optimum acoustic
performance in a compact, elegant enclosure.
The key components in the 209 subwoofer are the
drive unit, the amplifier and the enclosure – all three
of these contain innovations that make this model a
class leader.

The 18” (450mm) drive unit is designed to give
60mm (peak to peak) of linear excursion.
The magnetic field, which powers the motion, is
constant over that region.
The magnet system is a
radically different design
from that found in
conventional loudspeaker
drivers, it has been
designed by KEF from the
ground up using advanced
computer modelling techniques to predict the
behaviour and orientation of the internal magnetic
field. Unlike conventional drivers the Reference 209
magnet system uses a series of 24 neodymium
magnets radially arranged around the voice coil of
the driver. This unusual topology allows the unit to
have a remarkably long range of motion while
maintaining a very strong magnetic field around the
voice coil. Together with a double suspension and
massive roll surround this allows high levels of bass
to be reproduced with very low distortion - giving
a sense of power and clarity not normally found in
high end subwoofers.

The amplifier section is custom designed to get the
very best out of the new drive unit. A 1000W class
D power amplifier with switched mode power
supply allows top end performance in a neat and
tidy package. In addition, the front end
incorporates Digital Signal Processing (DSP) which
is used to provide comprehensive equalization
options and an innovative room acoustic
correction system (see page 9 for an overview and
page 23 for operation guide).

The enclosure is beautiful on the outside and highly
technical on the inside. Attached to the inner
surface are 30 ‘ACE’ modules - tubes of activated
carbon which increase the effective internal
acoustic volume by a factor of 2. ACE technology

(see page 8) is KEF’s solution to the oldest catch 22
in loudspeaker design – that to get good bass
extension with good efficiency you need a large
enclosure. The Reference Series 209 subwoofer
gives the kind of bass extension normally found in
subwoofers twice the size.

This subwoofer is specifically

designed with bass speed and

articulation in mind, because of

this we chose to make the

subwoofer a closed box design.

A closed box design does not

rely on the resonance of port or

passive radiator for output.

All sound radiation is from the
18” driver the motion of which
is carefully controlled and

damped by the amplifier and

large magnet system, there are
no port resonances to continue
ringing after a sudden bass event.

Additionally it is not possible to

recreate extreme low bass

output with a ported system,

which cannot radiate below the

port tuning frequency.

All this technology is neatly packaged in an
elegant enclosure with straightforward connection
options and an easy to use remote controlled
user interface.

You can run the Reference Series 209 subwoofer
with the default ‘switch on’ settings or experiment
with the DSP based equalisation options to fine
tune it to your particular system setup.

Line level or high level speaker inputs are available
to allow flexibility in set-ups. In addition, line level
connections are possible as either single ended
(phono) or balanced (XLR).

For ease of use and installation the subwoofer is
equipped with an IR remote control allowing for
easy adjustment of subwoofer level, cut off
frequency and phase from your listening position.
A microphone is also included to allow the
subwoofer to measure the sound produced within
your room and compensate for abnormalities using
integrated room correction algorithms.

7

ACE technology

Room Correction

The laws of physics dictate that to get good bass
extension out of a loudspeaker you need a large
enclosure volume, and to get high output levels you
need to move a lot of air. This is why the more
expensive loudspeaker systems have large or
multiple bass drivers and big enclosures.
Many potential solutions to the enclosure size
problem have been tried over the years, but KEF’s
ACE technology is the one which genuinely works
and is useable in production systems.

ACE stands for Acoustic Compliance
Enhancement. Granules of activated carbon are
packed into porous fabric tubes and fitted inside
the loudspeaker enclosure. These carbon
granules are highly porous with many pores,
macropores and micropores giving them an
incredibly high surface area. ACE works by
a process called ‘adsorption’. It’s a physical
process whereby the granules of
activated carbon continually work to
reduce the acoustic pressure within
an enclosure. When the drive unit
cone moves inwards the air
pressure inside the enclosure
increases. This triggers the
carbon granules to pull air
molecules onto the
surface of the material
by the weak, gravity
type, Van de Waals force.

This has the effect of reducing the overall air
pressure inside the enclosure. When the cone
moves out, and acts to expand the air inside the
enclosure and reduce its pressure, the granules

‘give out’ air molecules, again reducing

the pressure change. A smaller

change in the internal

enclosure pressure

is equivalent to

having a larger enclosure

volume. So by placing

modules of activated

carbon granules inside the

enclosure we are getting the

acoustic performance of an

enclosure with a much larger

physical volume.

The adsorption process is linear

and reversible, there is no distortion

introduced because of the operation

of the carbon granules. In fact, the

bass quality of ACE loaded enclosures

is consistently admired by audiophiles

for its clarity and detail.

The listening room has a major impact on the
sound of loudspeakers, particularly at low
frequencies. In this region, standing wave
resonances in the room result in large peaks
and dips in the loudspeaker response.

It is very difficult to compensate for the effect
of the room. This is mainly because the effect is
not uniform but is different at every location in
the room. If one were to perfectly correct the
subwoofer response in one location it would
inevitably become worse elsewhere.
KEF engineers made the discovery that the
acoustic behaviour of the room can be
separated into two distinct parts, one part that
describes all of the spatial variation in the room
and a second part that describes the resonant
behaviour in the room. As this second
resonant part is independent of the
loudspeaker and listener positions it can be
electronically corrected for all locations in the
room simultaneously.

KEF has developed an innovative room
correction system that analyses the acoustical
characteristics of the room and then designs a
digital compensation filter to optimally correct
the subwoofer response. This method of room
correction gives a very significant audible
improvement in the subjective performance
of the bass, it sounds tighter and more defined.
Best of all, it works wherever you are in
the room.

Before room correction.

After room correction.

An additional benefit of this method of room
correction is that it makes positioning of the
subwoofer much simpler. Traditionally it is
advisable to position subwoofers away from
walls and corners as these locations result in
very strong excitation of the room resonances.
With the KEF room correction system,
however, the resonances are electronically
compensated and there is no problem with
locating the subwoofer close to walls or in the
corner of a room.

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9

Installation and Operation

Unpacking, Handling and Aftercare

sunlight should, if possible, be avoided.
Furthermore the cabinet should not be allowed
to become wet.

Each Reference Series 209 subwoofer is supplied
with KEF designed substantial spikes and locking
nuts (also in the care pack). This enables fine
adjustment of level, depending on your preferred
location of the loudspeakers whatever the floor
covering: carpet, tile or block wood. In addition
to the spikes and locking nuts each Model 209
also comes with casters. The casters should only

Accessories

be used for transporting and moving the
subwoofer as they do not offer the stability
required when the subwoofer is in operation.

The Reference Series 209 subwoofer is of a
closed box design. As well as producing the best
acoustical performance, the cabinet is sealed to
prevent moisture ingression. It is therefore
important that the rear panel, drive unit and trim
ring are not removed for any period of time
especially in a humid environment.

Unpack your subwoofer carefully and inspect for
any sign of damage. Your subwoofer left KEF’s
manufacturing facility in the UK in perfect
condition. If any damage is apparent, you should
notify your retailer or consultant immediately.
Retain the packaging in case a need arises for you
to transport the subwoofer at a later date.

You will notice that a special KEF care-pack is
included with the subwoofer. This pack contains
a cleaning cloth and all the required accessories
for connecting and positioning your

loudspeakers. The care pack also contains the
unique product build certificate. This is a valuable
document and guarantees the quality and
craftsmanship of your subwoofer.

The cabinet is finished in real wood veneer and
should be treated with the same care with which
you would treat fine furniture. A suitable cleaning
cloth is included in the customer care pack to
maintain the original finish and lustre. It is normal
for the appearance of wood veneer to change
with the passing of time, but locations in direct

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Adjusting the Feet and/or Spikes

Subwoofer Positioning

Under normal circumstances your subwoofer will be
commissioned by your retailer or consultant, who
will have been trained in their installation by KEF.

KEF strongly recommend that you do
not attempt to level your loudspeakers
single-handed. Recruit the assistance of another
adult - or consult an authorised KEF Reference
outlet for assistance which may be chargeable if the
purchase was not made through them originally.

The spike/locking nut combination supplied is
designed to provide small adjustments, not to
compensate for seriously irregular floors.

Best results will be obtained if the subwoofer is
level and stable. Check the general stability of the
subwoofer by gently rocking it from side to side,
front-to-back and diagonally. Adjust the height of
each foot to ensure that the subwoofer does not
rock at all.

The listening room is one of the most variable
elements in the hi-fi chain and its effect cannot be
emphasised too strongly, nor can its effects be
reliably predicted. This is where the room
correction feature on the Reference Series 209
subwoofer becomes such an important feature.

As the sub-bass (low frequency) sound produced
by the subwoofer is close to omni-directional
positioning of the subwoofer is less critical than
with full range conventional speakers.
However, it is advised that the subwoofer is not
positioned too close to the listener.

It is often recommend that subwoofers are not
placed in the corners of the room, near soft
furnishings (which will deaden the sound) or near
reflective surfaces (which may brighten up the
sound). The room correction feature of the

Reference Series 209 subwoofer will help
compensate for all these effects.

KEF recommend you to place the Reference
Series 209 subwoofer in a central position in the
room and execute the room correction setup.
This is an initial compensation for your unique
room. Then move the subwoofer into a few
acceptable positions and compare the sound.
Pick the location which gives the most satisfying
sound available from the room.

When the subwoofer is in its final chosen
position, then repeat the room correction setup
and select the preset equalisation setting to
optimise the sound further.

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13

Rear Panel Information

Mains power socket and fuse holder.

Please check that the voltage indicated is correct
for your country’s mains supply voltage as this
subwoofer comes in 110V or 240V versions that
are not inter-changeable. Please return to your
KEF retailer if the setting is incorrect for the
voltage supply in your country so that it can be
changed internally.

On/Off switch.

Please turn off your subwoofer during long
periods of non-use.

Speaker/high level input.

Used when the subwoofer is to be driven from
the output of the main speaker power amplifier.

Line input Left and Right.

These are used to connect the subwoofer to the
line level signal from a pre-amplifier. Please note
that single ended (phono) or balanced (XLR)
connections are available however they must not
be used simultaneously. If only one set of line
outputs is available on your pre-amplifier use Y
connectors to split the L and R signals between
the pre-amplifier and the KEF Reference Series
209 subwoofer or use the Line level LFE input
described below.

Line input LFE.

This dedicated line level input is specifically for
LFE (Low Frequency Effects) output from a
surround sound processor. Please note that
single ended (phono) or balanced (XLR)
connections are available however they must not
be used simultaneously. The LFE input to the
subwoofer is not be affected by the frequency or
slope settings so there will be no conflict with
the bass management settings applied by the
external surround sound processor.

Microphone input.

Connect the supplied microphone with the XLR
cable to the microphone input and execute
the room correction setup. The microphone may
be removed after this set up has been
fully completed.

External IR input.

The Reference Series 209 subwoofer is only
controllable with the supplied remote control.
However the supplied external IR receiver can
be connected to this input enabling reception
from the remote control even if the subwoofer is
hidden out of site of the remote control and the
main listening position.

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