KEF REFERENCE 201/2 Service manual

VISIONARY
Quality. Honesty. Innovation.
These qualities are why KEF commands such
respect among audiophiles. Ever since the
pioneering acoustics engineer Raymond Cooke
founded the company in 1961, KEF innovation
has helped to shape the evolution of modern
audio technologies.
His vision holds true today, in a brand driven by
original thinking and engineering integrity rather
than passing fads. No other manufacturer
can claim such a distinguished design pedigree,
from revolutionary driver concepts and the use of
radically new materials to a host of patented
refinements that transform the listening experience.
But making great loudspeakers is an art as much as
a science, and these innovations are all designed to
enrich that emotional experience by achieving the
clearest, purest sound.
Welcome to the world of KEF Reference Series.
Photograph : Martyn Goddard. Courtesy Sunday Telegraph Colour Supplement.

HERITAGE
In a world where everything is relative,
KEF Reference Series has always stood for
absolute standards.
The design approach has always been consistent:
to give some of the world’s most gifted acoustics
engineers the freedom to set a new performance
yardstick. After years of research and painstaking
development, the resulting conceptual
breakthroughs are built into prototypes that are as
close to perfect as possible.
After exhaustive measurements and listening tests
using different media under anechoic conditions and
in real rooms, each prototype is fine-tuned to
become ‘the reference’ to which every production
version must conform. Each speaker is then
hand-assembled by a skilled craftsman who matches
the performance of each driver to within 0.5dB.
It’s a process that takes time, skill and patience – but
it creates a range of loudspeakers that continue to
redefine the boundaries of sonic performance.
Meet the new benchmark.

PRECISION
As KEF’s signature technology, the Uni-Q concept is
renowned for its uncannily natural sound and stable
imaging. In the Uni-Q configuration the tweeter is
mounted at the centre of the midrange cone so that
their acoustic centres are at the same point in space.
The outputs from the two units are thereby time
aligned and will sum perfectly for all listening
positions. The profile of the midrange cone controls
the directivity of both drive units so it acts not only
as a superior midrange radiator but also as the
optimum waveguide for the upper registers.
Now, after nearly two decades of continuous
development and a host of new patented
refinements, every component of this uniquely
advanced driver array has been redesigned to
achieve a quantum leap in performance.
The tweeter now has a vented motor system with
three rare earth magnets, and a unique braced dome.
The midrange unit has a low profile surround that
eliminates edge diffraction effects.These innovations
take Uni-Q performance to a new level.
Dispersion is wider still. Power response is even
more uniform.Tonal balance is more realistic across
both direct and reverberant fields. Multi-channel
imagery is clearer and more accurate than ever.
UNI-Q®

AUSTIN
Interesting things can happen when you push
beyond normal limits.
Senior Acoustics Engineer, Dr.Andrew Watson and
the Reference Series design team set out to build
the most natural sounding loudspeakers possible,
irrespective of cost or practical constraints.
The ‘Austin’ concept was the result – a technological
tour de force standing two metres high and weighing
more than 120 kilos apiece. Awesome is the only
word to describe how they sound.
The project became the technology testbed for the
new Reference Series. The two-piece compound
titanium tweeter dome whose pistonic motion
reproduces higher frequencies with such effortless
clarity; the new shallower midrange cone that
disperses the soundfield so broadly; the elegant
fourth-order crossovers, computer-optimised for
superior driver integration.
Big ideas. Big sound. Big benefits.
GROUNDBREAKING

CROSSOVER
The new Reference Series responds even more
musically than its acclaimed predecessors by combining
design innovation with an exceptionally rigorous
approach to the specification of each component.
The crossovers, for example, are computer-modelled
to optimise amplitude and phase behaviour for the
smoothest possible integration. Not only are
the crossover boards decoupled to isolate them
from cabinet wall vibration and to stabilise them
against the high acoustic pressures inside, but the
multi-board construction also eliminates crosstalk
between the different sections.
High saturation iron powder core inductors are
selected for bass sections, where large inductance
values and low resistance are required; air cored
inductors are used elsewhere for their superior
linearity. Similarly, there are high quality bipolar
capacitors for low frequencies, and very low loss
polypropylene capacitors for the upper ranges.
High power rated wire-wound resistors are
specified throughout to assure minimal
compression and maximum linearity.
Hidden away as they are, as much care has gone
into the design of these aspects as those that are
visible. And the difference is plain to hear.
INNOVATION

DEDICATED LOWER MIDRANGE
KEF’s high-end Uni-Q loudspeakers have had the
benefit of a dedicated lower midrange driver since
1989. By allowing each section of the frequency
range to be optimised for its specific role,
this configuration creates much smoother
transitions between the Uni-Q array and the bass
drivers. The integration is so precise that it’s
virtually impossible to hear that the sound is being
generated by a four-way configuration.
The resulting acoustic performance is markedly
superior, with the delicacy and precise imaging of
KEF Uni-Q perfectly complemented by the scale
and impact of a truly assertive bass section.
The 250mm (10in.) lower midrange driver of the
Model 207/2 has a distinctive chrome ‘phase plug’
at its centre to optimise its acoustic response.
A lightweight neodymium magnet assembly allows
the unit to be mechanically decoupled from the
cabinet to minimise the transmission of vibration
and to ensure that its sonic purity matches that of
the bass and Uni-Q sections.
SOUND THINKING
KEF Reference Series cabinets are works of art in
themselves, quite apart from all the high-end
technology they enclose.
It’s not just the sumptuous choice of finishes
(although the silky pale Satin Sycamore and the
sheer depth of the High Gloss Cherry, American
Walnut and Piano Black finishes do admittedly hint
at the uncompromised build quality).
What’s so special about these curved section
cabinets is how they perform – and why.
Precision engineered from beech ply, they’re
designed to eliminate every unwanted vibration
that would otherwise muddy the sound.
Massive internal bracing tailors the volume of each
enclosure to the exact parameters of its drive
unit, and mechanical and acoustic damping ensures
an inert structure that never colours the
inherently natural sound.
With independent driver loading and KEF’s proven
decoupling techniques, these are cabinets that do
nothing to mask the performance of the
components inside.
No panel resonance. No standing waves.
No stray reflections. No box colorations.
Just pure, sweet sound.

ATTENTION TO DETAIL PRIDE
For all the technological innovation inside the new
Reference Series, the personal commitment to
build quality remains true to the uncompromised
standards originally set by Raymond Cooke.
The exceptional finish speaks for itself, but the same
obsessive attention to detail applies to the parts you
never see. KEF’s own graded OFC (Oxygen Free
Copper) cable is soldered by hand and the drivers
are magnetically shielded to prevent interference
with your TV. Signal transmission is optimised on
all models by having three pairs of fully shrouded
gold plated WBT®terminals to allow tri-wiring
or tri-amplification.
Naturally, performance can be fine-tuned for
your room acoustics. The KEF Uni Balance
feature allows you to adjust bass output to
compensate for the proximity of the
loudspeakers to the walls. At the high frequency
end, a four-position adjustment gives ample
‘brightness’ control to compensate for the
room’s sound absorption characteristics.
The Reference concept is all about pleasure
that lasts. So when you open the polished
wooden case that comes with your loudspeakers,
you’ll find a certificate of authenticity signed by the
craftsman who made them, along with your
Reference Series manual and all the accessories
you’re ever likely to need .

MODEL 207/2
In a word, bliss. As KEF’s flagship loudspeaker,
every inch of Model 207/2 is designed to make
what you hear sound totally real.
This is where all the latest KEF technology
breakthroughs find their finest expression; sound
quality, bandwidth and dynamics are second to
none. Bass extension is phenomenal, thanks to a
pair of 250mm (10in.) ultra-low distortion drivers
independently housed in 70-litre reflex enclosures.
A dedicated lower midrange driver of the same
size adds the control and finesse required in this
crucial register while assuring perfect integration
between the bass drivers and the stunning new
Uni-Q array. And with its unrivalled linearity, the
Uni-Q has exceptionally wide dispersion and
unerringly precise reproduction across both
midrange and high frequencies. By faithfully
tracking every last subtlety of the recording, it
generates a soundfield of startling realism.
This technological sophistication produces
loudspeakers that seem to disappear: all you
experience is the sensation of actually being close
to the original source of the sound.
ICONIC