KEF R300, R900, R100 User Manual
Electronically reprinted from August 2012 Volume 19 No. 8
HIGH END
BY Mark Fleischmann
KEF R300 Speaker System
PRICE: $6,800 AT A GLANCE: Three-way with coaxial midrange/tweeter • Sub with dual
side-firing drivers
• Laser-like focus and well rounded
Tangerine Dream
ent, in the south of
England, was best
known for hop
farming when
K
Wharfedale and founded KEF in
1961. e company was named
aer the industrial site on which it
was founded: Kent Engineering &
Foundry. KEF’s numerous
distinguished alumni include
Laurie Fincham, who now
develops next-generation audio
technologies for THX, and
Andrew Jones, who designs
world-beating loudspeakers at a
variety of price points for Pioneer
and TAD. KEF has earned a
reputation for making both great
speaker systems and great speaker
drivers, some of which were
instrumental in the legendary
BBC-designed LS3/5A, which
KEF and other manufacturers
have marketed in various forms.
Roving through a New York
cocktail party celebrating KEF’s
50th anniversary last year,
hobnobbing with the audio elite, I
found that the drive units inspired
as much nostalgia as the speakers
in which they were used. (To read
about KEF’s history in more
detail—and in a handsome
coee-table book, no less—see
KEF: 50 Years of Innovation in
Sound by Ken Kessler and Dr.
Andrew Watson.)
Raymond Cooke le
KEF R300 Speaker System
PERFORMANCE
BUILD QUALITY
VALUE
Muon, Blade, and Beyond
KEF’s current product roster is
worth a book in itself. If you’re
looking for a speaker about as tall
as you are, KEF oers two towers
that would dominate a large
space: the curvaceously sexy yet
monumental Muon, and the more
slender Blade. e latter, billed as
the world’s rst “single apparent
source” speaker, has two sets of
woofers set into the sides in
opposing pairs plus a Uni-Q
coaxial driver array in front.
Uni-Q is the key to KEF’s
kingdom, so we’ll return to that in
a moment.
KEF’s Home eatre lines
include the KHT Series, with its
oval-shaped satellite/subwoofer
sets; the T Series, a at-panel
solution; and the Fivetwo, which
claims full 5.1 surround using two
speakers and a sub. KEF covers
the custom-installation eld with
the in-wall CI Series and the
all-weather Outdoor Series.
ere’s also a Universal Wireless
System that oers quality sound
transmission while operating in
the 2.4-gigahertz band. But the
heart of the KEF family is a
comprehensive selection of what
the company calls Hi- speakers
that can be congured for
surround or stereo listening.
ese six lines, spanning a wide
range of prices, break down into
those with curved enclosures and
those with simpler rectangular
builds. e curvy ones are the
Reference Series, XQ Series, and
Classic Q Series. e boxier and
more aordable speakers are the
Q Series, C Series, and the subject
of this review, the newly
introduced R Series.
e newly introduced R Series
(which will replace the XQ in
KEF’s lineup) is positioned as an
aordable alternative to the
pricier Reference Series,
borrowing design features from
both the Reference and the
bleeding-edge Blade tower.
Reviewed here are the R300
three-way monitor ($1,800 per
pair), R600c center ($1,500),
R800ds dipole surround ($1,800
per pair), and R400b subwoofer
($1,700 each), for a total system
price of $6,800. Also available is
the smaller, two-way R100
monitor ($1,200 per pair), whose
5.25-inch woofer would imply
that it should mate well with the
smaller R200c center ($1,000).
And there are three tower models:
the R900 ($2,500 each), R700
($1,800 each), and R500 ($1,300
each), dierentiated by their 8-,
6.5-, and 5.25-inch woofers.
While the R-Series enclosures
may look like simple boxes, they
are anything but simple on the
inside. To minimize cabinet
resonance, KEF uses what it calls
“constrained layer damping,” with
damping panels of dierent
materials and thicknesses
positioned in strategic places. is
may be part of what gives the
speakers the clean sound I’ll
describe in more detail later. e
designers also went out of their
way to tame port turbulence using
computational uid dynamics.
(KEF claims to be the rst speaker
maker to integrate computers into
the design process back in the
early 1970s.)
Like most of the R Series, the
R300 monitor and R600c center
have 1-inch tweeters and 5-inch
midrange drivers built into KEF’s
classic Uni-Q array. at means
the tweeter is mounted coaxially
(or concentrically, if that makes it
easier for you to visualize) into the
center of the midrange driver.
at in turn eectively allows the
two drivers to act as a single point
source for the frequencies they
cover: 500 hertz to 2.8 kilohertz
for the midrange, 2.8 kHz and up
for the tweeter.
KEF R300 SPEAKER SYSTEM
SpecS
SPEAKER:
TYPE:
TWEETER (SIZE IN INCHES, TYPE):
MIDRANGE (SIZE IN INCHES, TYPE):
WOOFER (SIZE IN INCHES, TYPE):
NOMINAL IMPEDANCE (OHMS):
RECOMMENDED AMP POWER (WATTS):
AVAILABLE FINISHES:
DIMENSIONS (W X H X D, INCHES):
WEIGHT (POUNDS):
PRICE:
Coaxial arrays bring the risk of
a cupped-hands coloration as the
tweeter’s output bounces o the
midrange’s cone. But KEF’s long
experience with Uni-Q, rst introduced in 1988 and steadily rened
ever since, has eliminated this
potential side eect. “e key is
getting the geometry of the
tweeter dome and waveguide,
formed by the cone, exactly
correct,” KEF research engineer
Jack Oclee-Brown explains. “en
the performance of a tweeter positioned in a waveguide can actually
be better than one mounted
directly on a bae. is was
something we rst discovered
when working on the Uni-Q for
the Muon.”
Pull the magnetically attached
grille o any R-Series bae, and
the speaker’s quiet appearance
takes on shiny metal accents in
the aluminum trim rings
surrounding the drivers and
within the drivers themselves. e
rear-vented tweeter—optimized
to move like a piston over its
entire working range—is adorned
with a tangerine waveguide that
visually resembles the blades of a
jet turbine more than the
segments of a piece of citrus. It’s
designed to control the tweeter’s
response and dispersion to more
closely match the output of the
R300 R600C R800DS
Three-way, monitor Three-way, center Three-way, dipole surround
1, aluminum dome 1, aluminum dome 1, aluminum dome (2)
5, aluminum cone 5, aluminum cone
6.5, aluminum cone 6.5, aluminum cone (2) 5.25, aluminum cone (2)
8 8 8
25–120 25–200 25–100
Rosewood, Walnut Veneer,
Piano Black
8.3 x 15.2 x 13.6 24.8 x 7.9 x 13.2 13.8 x 7.1 x 7.2
26.4 37.9 16.3
$1,800/pair $1,500/each $1,800/pair
midrange driver, which is
constructed with a die-cast
aluminum basket. e aluminumconed woofer is billed as “light,
sti, and strong.” In practice, I
found it to be nimble, allowing
bass frequencies above the sub
crossover to manifest as tightly
controlled pitches, free of the
obvious bloat that sometimes
plagues speakers great and small.
In the R300, the 6.5-inch
woofer sits below the coaxial
midrange/tweeter array, while in
the R600c, two 6.5-inch woofers
ank the coaxial array. e
midrange cone is an alloy of
magnesium and aluminum, while
the woofer cone is an aluminum/
paper hybrid and the tweeter
dome is pure aluminum. All are
said to be similar to the drivers in
the big, bad Blade.
e R800ds dipole surround
has two Uni-Q arrays—each with
a woofer and a tweeter—built
onto either side of an enclosure
that’s trapezoid shaped when
viewed from above. Note that the
two woofers are 5.25 inches, not 5.
is speaker is not a bipole/
dipole: It’s not switchable for
bipole operation. It works only in
Rosewood, Walnut Veneer,
Piano Black
dipole mode, with the driver
arrays moving out of phase with
each other: When one set moves
in, the other moves out. However,
in an unusual twist, the two sets of
drivers don’t operate identically
throughout the frequency spectrum. One woofer and tweeter
array operates only above 300 Hz,
while the other works down to the
specied low-frequency limit of
90 Hz. e goal is to prevent the
two out-of-phase woofers in close
proximity from canceling bass
frequencies, as might happen in a
conventional dipole. Only one
woofer produces bass up to the
point where the dipole radiation
pattern becomes eective. en
the two sets of drivers operate in
classic dipole mode.
e R400b subwoofer, with its
dramatic metal stripe running
across the top and down the front,
has two 9-inch drivers on either
side of the enclosure—a design
feature borrowed directly from
the Blade tower. e opposing
drivers both move outward or
inward together, so that their
vibrations cancel and don’t
transfer to the cabinet. KEF
uses an acoustic suspension
Rosewood, Walnut Veneer,
Piano Black
•
enclosure—in other words, a
sealed box—eliminating the port
and any concomitant turbulence.
While it’s possible to design a
great-sounding woofer that gets
some of its output from a port, the
sealed-box approach provides a
more disciplined feel that, in my
opinion, serves music better and
makes the low-frequency eects
of action movies a little less
aggressive and vulgar. Each
aluminum driver is propelled by a
250-watt, Class D amplier, for a
total output-power rating of 500
watts. KEF provides stereo RCA
line-level inputs and plug-in
speaker-level inputs. In addition
to the usual volume knob,
crossover knob, and phase switch,
there’s a three-setting bass boost
(0, +6, +12 decibels) centered on
40 Hz. I was never less than
satised with the zero setting.
KEF’s distinctive approach to
everything includes the troubleshooting section of its manual, or
in KEF-speak, the Fault Finding
section. It takes the form of three
columns labeled Problem, Action,
and Cause. e columns contain
graphics representing speakers,
ampliers, and cables—which are
further decorated with icons that
signify working, not working,
switch cables, treble, midrange,
bass, intermittent sound, and
distorted sound. e master list of
icons is captioned in 15 languages,
but apart from that, the approach
is primarily pictorial, and it saves
many pages of multilingual
duplication.
For this review, associated
equipment included a Pioneer
Elite VSX-53 A/V receiver, a
Panasonic DMP-BD87 Blu-ray
player, a Micro Seiki BL-51
turntable (a mint-condition
vintage model making its Home
eater debut), an Onix OA 21s
integrated amp operating as a
•
The tweeter features
•
a wave guide that’s said
to resemble the segments
in a tangerine
The R Series speakers are
•
available in Piano Black,
Walnut, and the Rosewood
.
finish shown here.
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