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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.
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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.
Page 3
HT Labs
Measures
KEF R300 SPEAKER SYSTEM
L/R Sensitivity:
90 dB from 500 Hz to 2 kHz
Center Sensitivity:
90 dB from 500 Hz to 2 kHz
Surround Sensitivity:
85 dB from 500 Hz to 2 kHz
his graph shows the
quasi-anechoic
(employing closemiking of all woofers)
T
frequency response of the R300 L/R
(purple trace), R600c center channel
(green trace), R800ds surround (red
trace), and R400b subwoofer (blue
trace). All passive loudspeakers were
measured with grilles at a distance of
1 meter with a 2.83-volt input and
scaled for display purposes.
The R300’s listening-window
response (a five-point average of axial
and +/–15-degree horizontal and
vertical responses) measures
+1.03/–3.07 decibels from 200 hertz
to 10 kilohertz. The –3-dB point is at
KEF R300 SPEAKER SYSTEM
expla nation of ou r
54 Hz, and the –6-dB point is at 42
Hz. Impedance reaches a minimum
of 4.25 ohms at 158 Hz and a phase
angle of –28.40 degrees at 4.7 kHz.
The R600c’s listening-window
response measures +0.84/–2.49 dB
from 200 Hz to 10 kHz. An average
of axial and +/–15-degree
horizontal responses measures
+0.97/–2.12 dB from 200 Hz to 10
kHz. The –3-dB point is at 55 Hz,
and the –6-dB point is at 44 Hz.
Visit o ur Website
for a det ailed
testing regimen,
plus a li st of our
reference gear.
on the
web
Impedance reaches a
minimum of 4.04 ohms at
137 Hz and a phase angle of
–31.95 degrees at 4.3 kHz.
The R800ds’s three-face
averaged response measures
+2.23/–4.49 dB from 200 Hz
to 10 kHz. The –3-dB point is
at 98 Hz, and the –6-dB point is at
77 Hz. Impedance reaches a
minimum of 4.21 ohms at 347 Hz
and a phase angle of –42.79
degrees at 96 Hz.
The R400b’s close-miked
response, normalized to the level at
80 Hz, indicates that the lower
–3-dB point is at 42 Hz and the
–6-dB point is at 36 Hz. The upper
–3-dB point is at 123 Hz with the
Crossover control set to maximum
and the EQ switch set to +6
dB.—MJP
SPECS R400b SUBWOOFER
ENCLOSURE TYPE: Sealed WOOFER (SIZE IN
INCHES, TYPE): 9, aluminum RATED POWER
(WATTS): 500 peak, Class D CONNECTIONS:
Line-level stereo input, RCA/speaker-level
input, Terminal Block Plug CROSSOVER
BYPASS: No AVAILABLE FINISHES: Piano Black
DIMENSIONS (W X H X D, INCHES): 13 x 14.4 x
13.8 WEIGHT (POUNDS): 47.4 PRICE: $1,700
pronounced with the passage of
time. Aside from that, these
speakers delivered everything I
hope for when I sit down to listen
to music or movies.
One of those things was a tonal
balance I found free from gross
aws and subjectively pleasing.
Whether it’s objectively truthful, I’ll
leave that to the measurements.
ere were individual pleasures
to be had in every band of the
frequency spectrum, from palpably
physical midbass to top-end air.
And the R400b sub delivered the
lower bass in just the kind of
subtle, sealed-box fashion I prefer.
But the part that was most
refreshing—like a pint of good
bitter made with aromatic Kentish
hops—was the clean and beautifully proportioned midrange,
which made voices in particular
communicate at a Shakespearean
level of achievement. Both the
actor (to continue the metaphor)
and the soundstage on which he
played were focused to a farethee-well, a strength of the coaxial
midrange-tweeter array. Objects
were physically solid and had
discernible—but not cartoonishly
overdrawn—boundaries within a
well-depicted space. is was as
true in 2.0 and 2.1 channels as in
5.1, although the point-ones were
of course better lled out at the
bottom end. My comfort level was
high, and my emotional pleasure
receptors were comprehensively
stimulated.
One thing that distinguishes a
great speaker is that it changes the
way you listen—for the better.
When I hit the play button on
Dream House, a haunted-homeowner tale starring Daniel Craig,
avoiding discomfort never
became a preoccupation. Instead,
I concentrated on nding the
right balance of dialogue, eects,
music, and surround envelopment. Rather than start high and
push the volume down, I started
low, because the coaxial array
made enunciation so unambiguous that I had no trouble catching
dialogue at levels probably lower
KEF R400b Subwoofer
PERFORMANCE
FEATURES
BUILD QUALITY
VALUE
phono preamp, and a Shure
M97xE moving-magnet cartridge.
All movie demos were Blu-ray
Discs with DTS-HD Master
Audio soundtracks. Music demos
were primarily analog, with just
enough digital to plant a foot in
the present tense.
Actorly Enunciation
I interrogated these speakers at
unusual length, looking for
C
positive and negative traits that I
might translate into words. e
list of positives was long and the
list of negatives almost blank. My
only reservation was the
diuseness of surround eects,
but that was more an inherent
characteristic of dipole surrounds
than a performance aw. My
preference for surround
monopoles (that is, conventional
speakers) is becoming more
Page 4
KEF R300 SPEAKER SYSTEM
•
The R800ds has a Uni-Q array built into
•
each side of its trapezoid-shaped enclosure.
than the mixer intended. When it
became apparent that le/right
and front/back eects were
elusive, and the soundeld was
too front loaded, I pushed up the
master volume to achieve more
palpable dynamics, more detail,
and more sense of space; basically,
I wanted more of everything.
Music was so vivid that I was
tempted to pause the movie and
enjoy a symphony or six (and
when I eventually did, the system
did not disappoint).
I continued to ride the Daniel
Craig train with the American
remake of e Girl With the
Dragon Tattoo. e cover version
of Led Zeppelin’s “Immigrant
Song” grabbed me by the throat. I
continued dialing in surround
eects until howling winds really
howled in all ve channels. Now I
could hear a pin drop—or could
have, if someone had dropped
one. What I did hear was
heightened detail in indoor
scenes (the gentle creak and rustle
of clothing) and heightened
ambience in outdoor ones
(nonviolent in-car hum and
the gentle movement of air) as
the R300, R600c, and R800ds
combined to produce an
involving soundeld. When the
drama hit its peaks, I was on the
edge of my seat and in a dierent
world—ears comfortable but
emotions tense. If this movie
had lasted another 10 minutes,
tattoos and piercings might
have spontaneously broken out
on my body.
Recoil—with former wrestler
Steve Austin as a vigilante ex-cop
who takes on a gang of equally
bulky leather-jacketed thugs—is
the kind of high-energy action
movie that attens inner-ear
hairs at a dozen paces. In other
circumstances, I might have used
a low-volume mode to take the
edge o. (Indeed, the Pioneer’s
THX Loudness Plus mode did
just that for a few minutes.) But
because the speakers rendered
dialogue so intelligibly, I could
cruise at a low volume and catch
everything. e sub’s carefully
measured bass made lowfrequency eects not only
bearable, but pleasurable. Again,
I eagerly anticipated moving on
to music.
Dancing Diamond
I listened to a lot of analog and
two-channel material while the
R Series was in town—ttingly,
because KEF’s history starts in the
vinyl era, and the company began
its upward trajectory when the
average listener plowed black
grooves with a dancing diamond.
e Nick Drake compilation
Time of No Reply includes a
combination of studio tracks and
home demos. Concentrating on
the former (impeccably engineered by John Wood), I marveled at how the R300 dened the
dark-toned, melliuous voice as a
distinct object in discernible
space. Drake’s voice had a depth
that was well served but not
exaggerated by the woofers and
sub drivers. e sub’s contribution
was so subtle that I had to feel the
drivers with my ngers to make
sure they were operating. e
voice was also rich in overtones
and breath, none of which was
missed by the scrupulous
midrange/tweeter array. e
rhythm of Drake’s acoustic guitar
was snappy, as the woofers did an
excellent job of delivering Drake’s
nger-picking pulse. e guitar’s
harmonic signature rang true.
I played through all six
Vaughan Williams symphonies as
conducted by Sir Adrian Boult
with the London Philharmonic
and the New Philharmonia on a
series of Angel LPs. By the end of
the cycle, I had no doubt that the
speaker could produce a
convincing string sound in a
half-dozen distinctive ways. You
may be able to spot the woofermid and mid-tweeter crossovers
in laboratory measurements, but I
couldn’t spot them in the
orchestra.
e dening demo was the set
of Piano Etudes by Bartók, Busoni,
Messiaen, [and] Stravinsky that
Paul Jacobs recorded for
Nonesuch. As reproduced by the
R Series, the LP was timbrally,
harmonically, and rhythmically
ideal: as close to having a Baldwin
grand in my listening room as I’ve
ever heard. e sub and speakers
dovetailed beautifully at the
crossover, allowing slick transitions
between the pianist’s le and right
hands as he roved up and down
the keyboard. I’m not kidding
when I say this is something I’ll
remember all my life.
is seemed to be the right
time to play 50 Years of Innova-
tions in Sound, the CD compilation KEF produced for its 50th
anniversary last year. It’s a
refreshingly non-audiophile
selection of songs—but even the
most nicky listener would love
Astrud Gilberto’s honeyed vocal
on the famous version of “e
Girl from Ipanema” recorded with
João Gilberto and Stan Getz.
Secret Garden’s contemporary
gospel classic “You Raise Me Up”
was remarkable for both the
warmth of its solo violin and the
holographic vividness of the
choral vocals—further triumphs
for the midrange/tweeter array.
e speakers were capable of
making astonishingly tiny
distinctions: Tackling the piano
part on Nina Simone’s “Love Me
or Leave Me,” they depicted each
hammered note as a group of steel
strings. I noted the distinction
between these discrete microtimbres and the more unied sound
of the piano in the Paul Jacobs
selection.
Conclusion
It’s not always safe to assume
that a company with a grand
reputation will deliver on it with
each and every product. At the
same time, it’ll probably surprise
no one that the R Series is worthy
of its audiophile lineage. e
series is beyond excellent, moving
aggressively into I-could-live-this
territory. I’m struck by how much
this system excelled in the human
dimension—that is, the reproduction of speaking and singing
voices, although it also handled
pretty much all instruments and
eects with aplomb. And unlike
a lot of audiophile speakers,
these are no challenge for a
decent-quality AVR to run at a
variety of levels, from coherent
whisper to rambunctiously
rockin’. ese are simply
extraordinary loudspeakers.
(One nal word: If you can’t
nd KEF products, or a particular
one, for sale close to home, you
can order them directly from
kefdirect.com.)
* Audio editor Mark
Fleischmann is also the author
of the annually updated book
Practical Home eater
(quietriverpress.com).
KEF • (732) 683-2356 • kef.com
Posted with permission from the August 2012 issue of Home Theater® www.hometheatermag.com. Copyright 2012, Source Interlink Media, Inc. All rights reserved.
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