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Flagship elegance from
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THESHOW
10-11thSeptember

Wings’ iconic Band On The Run
artwork goes under the spotlight• PLUS 18 pages of music features • FROM THE VAULT Audiolab 8000A integrated UK £5.99 Aus $15.99• OPINION 12 pages of letters & comment • VINTAGE REVIEW Kenwood DP-1100SG• STUDIO TOURS Motown/Hitsville USA • READERS’ CLASSIFIEDS Hi-Fi bargains

Floorstanding three-way reflex-loaded loudspeaker
Made by: GP Acoustics (UK) Ltd, Maidstone, Kent
Supplied by: GP Acoustics (UK) Ltd
Telephone: 01622 672 261
Web: www.kef.com
Price: £30,000-£33,000 (depending on finish)

LOUDSPEAKERKEF Blade One Meta
KEF’s flagship Blade cuts to the heart of the music, andwith ‘MAT’ on board its edge has never been keener
Review: Andrew Everard & Paul Miller Lab: Paul MillerMore than a decade after theirlaunch, there’s still nothingquite like the KEF Blade Onespeakers. Well, OK, there’s
the smaller Blade Two [HFN Jul ’15], but
the point still stands! The result of oneof those ‘no constraints’ projects thatspeaker companies seem to love, theoriginal ‘Concept Blade’ created a stirwith its radical styling and carbon-fibreconstruction. The final retail version
employed a more production-friendly highdensity polycarbonate, but the speakers
were unmistakably the same, and just asunmistakably odd.
Yes, KEF has previous form in this ‘fromconcept to reality’ thing: after all, it did
make the huge – and arguably even morebonkers – Muon floorstanders [HFN May’08], which remain in the catalogue if you
happen to have £180,000 burning a holein your bank account. However, while
the Blade One – now in its
upgraded ‘Meta’ form – maylook as startling as it did
when it launched in 2011,
with its seemingly top-heavy
inverted propellor-vane
shape, there is solid methodin the apparent madness. Infact, the shape of the Bladeis key to KEF’s aim of a ‘Single Apparent
Source’ loudspeaker, one in which the soundcreated by the speaker appears to emanatefrom a single point [see PM’s boxout, p41].

units, endeavours to create the same effect,
but with greatly extended frequency range.
And at the risk of cutting to the chase so
early in our review, it pulls this trick off inspectacular fashion.
While the treble/mid Uni-Q driver in theBlade One Meta may look familiar to ownersof the ‘single driver’ LS50 standmount,the path of influence actually runs in
the opposite direction. In fact it was thedevelopment of the Blade’s Uni-Q that led
to the emergence of the LS50 [HFN Jul ’12],
a year after the original Blade speaker tomark the company’s 50th anniversary.
Subsequently, it’s hard to argue with theimpact the LS50 design has had on the KEF
range, spawning both wireless [HFN Oct ’17]and compact versions over the past decade.

SPECIAL SOURCE
When Quad launched its ESL-63 electrostatic back in 1981 it took the opportunity
not to drive the thin film panel uniformly over its entire surface. Instead it wasdriven from the centre outwards, in a series of concentric bands, the signal to eachprogressively delayed so that the entire panel delivered a spherical wavefront froma notional, and far smaller, acoustic centre. Easily achieved, perhaps, with only one‘driver’ but trying to emulate single-point source, if not a spherical wavefront, witha multi-way moving-coil loudspeaker is trickier still. An extreme example is provided
by Cabasse’s La Sphère [HFN Feb ’10], a four-way coaxial design that also relies
on digital filtering and delay to achieve a truly coincidental acoustic centre. KEF
attempted the same ideal, arguably with greater elegance, when it launched theoriginal Blade ‘Single Apparent Source’ speaker in 2011.
The Uni-Q driver [see exploded view, below, and MAT disc far right], with its
treble dome located in the throat and sharing the same acoustic centre as theperipheral midrange driver, gives KEF a head start. However, marrying this point
source to drivers covering frequencies below 350Hz required some leftfield
thinking. Left and right, as it happens, with a combination of four bass drivers
arranged in force-cancelling pairs on either side of the cabinet, equidistant aboveand below the Uni-Q driver. The opposing bass drivers necessarily have theiracoustic centre where the two magnets meet in the centre line of the cabinet, thehorizontal axis just fractionally behind that of the Uni-Q. But at bass frequencies,
where wavelengths are very long and output increasingly omnidirectional, theacoustic centre of this cluster of bass drivers is coincident enough to that of theUni-Q for KEF to claim a ‘single apparent source’. PMBlack hole

At the heart of the Blade One Meta is thelatest version of the Uni-Q, now in its 12thgeneration and completewith KEF’s Metamaterial
Absorption Technology –also used in the company’s
updated Meta versions of its
Reference series. The driver
combines a 25mm dome
tweeter with a stiffened
dome and a revised
tweeter gap damper to accommodate
the metamaterial absorber behind it.
This circular device uses a complex mazeshaped structure of channels to absorb aclaimed 99% of the sound from the rear of
the tweeter – or, as KEF puts it, it acts as
Taking centre stage‘an acoustic black hole’ – to give a purer,In practice, this is the thinking behind thecleaner mid/treble output [for a deep divecompany’s Uni-Q drive unit – a mainstay of
KEF designs since it debuted in 1988 – taken into Meta, see HFN Jun ’21].
Finally, the company’s familiar ‘tangerine’
to its logical conclusion. The Uni-Q places
segmented waveguide is used to control,
the tweeter at the centre of the midrangeand widen, treble dispersion. The tweeter
driver with the intention of deliveringsits in the throat of a 125mm aluminiumthe output of the two drivers as a single,
coherent whole. The idea is to enhancestereo imaging, focus and soundstaging,
RIGHT: Subtly remoulded, the latest Bladein a way that’s hard to achieve withOne (Meta)’s svelte polymer cabinet stands on
conventional drive units spaced apart.
a substantial oval plinth with sturdy feet (notIn the Blade model, the combination of ashown). Five cabinet finishes and six driver conesingle Uni-Q unit containing tweeter andcolours are offered – the ‘special order’ Piano
midrange, plus multiple side-firing bass
Black/copper Uni-Q variant is pictured here

‘Uni-Q is themainstay ofthe company’s
designs’

Reprinted from Hi-Fi News for global distribution | www.hifinews.co.uk

cone midrange unit with a new motor
designed for extremely low distortion [seePM’s interview with Jack Oclee-Brown, p43].
The surround is redesigned to allow longer
excursion while the profiles have beenreworked to smooth the transition from theface of the driver to the cabinet geometry.

Good vibrations
The Blade One Meta’s four bass drivers firesideways in horizontally opposed pairs, thus
cancelling out vibrations in the cabinet,with each pair in its own chamber within
the enclosure. These 225mm woofers haveslightly dished aluminium diaphragms, andemploy the technique found in the original
Blade of decoupling the voice coil from thecone, allowing lower-order crossovers toroll in the bass units at around 350Hz. As in
the original design, twin sets of terminals
LEFT: Now in 12th-generation guise the Uni-Qdriver comprises a 25mm alloy dome tweeter,with MAT rear absorber, set into the throat of a
125mm alloy midrange cone. Bass is handled by
two pairs of opposed (force-cancelling) 225mm
alloy woofers, reflex-loaded via two rear ports

are provided for bi-wire/bi-amping, with anovel twist selector that connects them forstandard, single-wire operation.
The cabinets are shaped with complex
parabolic curves to eliminate standing
waves within, and are acoustically inert.
The tapering design is stabilised by a hefty
base, this contributing to the 57.2kg weightof the speakers. For finishes, you can mix’n’ match enclosure colours with a rangeof anodising options for the Uni-Q driver.
So, you can have the Piano Black of thereview pair with a copper or grey driver;
Frosted Blue with blue or bronze driver;
Charcoal Grey with red or bronze; Racing
Red with a grey driver; or Arctic White witha champagne driver. And if that lot isn’t
choice enough, from June KEF will offer
Pantone colours at a 10% premium.

Blades of glory
Set up in PM’s listening room in accordancewith KEF’s detailed instructions – they canbe as close as 22.5cm from the rear wall,
but need to be a metre from side walls
due to those side-firing woofers – andwith a slight toe-in (KEF suggests no more

www.hifinews.co.uk | Reprinted from Hi-Fi News for global distribution

LOUDSPEAKERJack Oclee-Brown

Right: Pairs of 225mm alloy-coned bass
drivers work into separate chambers, each
set operating back-to-back to cancel out thelarge kinetic forces generated. Damping pads
supplement the cabinet bracing in key areas

than 10°), the imposing visual impression
created by these 1.59m-tall speakers isstriking… but the sound is even more so.
Right from the subtle opening murmurs
of Ravel’s ‘La Valse’ [Sinfonia of London/JohnWilson, Chandos CHSA 5280; 96kHz/24-bit],the Blade One Meta delighted with its
combination of soundstaging and focus.
This is clearly driven by those Meta-aided
Uni-Qs, the precision being of the kind one
would expect from very fine, but very small
speakers. That, in essence, is just whatthese speakers sound like – only with a lotof added clout and extension from those
big side-firing drivers, which really comeinto their own with the massed orchestra
and the thunderous percussion. Yes, bigdrums can shake the room, but it’s reallythe sheer impact that startles.
Similarly, the Blade One Metas soundmagnificent with the opening of the BachSt Matthew Passion in the recently released
Pygmalion/Raphaël Pichon recording[Harmonia Mundi HMM90269193;96kHz/24-bit], where the intensity ofboth performance and engineering
is immediately apparent in the dual
orchestras and the way the two choirs ask
and answer. These Blade flagships maintainthe unfolding drama and the running
commentaries of the arias, thanks to theirwonderful presence and definition, mostnotably in the section we always used tocall the ‘lightning and thunder bit’ when
I sung in choirs all those years ago.

Scintillating sonics
But you don’t need Sturm und Drang tohear the special qualities of the Blade
One Meta: with the title track of Doug
MacLeod’s A Soul To Claim [Fresh!/
Reference Recordings FR-746; 44.1kHz/
24-bit], the immediate impression is of theintimacy of the voice and guitar before theband kicks in, and the solidityof the sonic picture of thewhole ensemble. This kindof precision imaging is nevera given with large, weighty
speakers, and indeed seems
to elude many big-ticket
designs, however well they
do scale and substance.
Once again, these tall, slender KEF Blades
do that ‘small speakers but big’ thing in
scintillating fashion, and in so doing soundlike no other design I can recall – in a goodway, of course.

Track after track, album after album,
these top Blades demonstrated that elusive‘musicians located in space’ effect. Rarely
have I heard a design so entirely able tocreate a sonic image free from the cabinets
before the listener, and with such complete
focus and apparent front-to-back depth.
This was as evident with the senseof the concert hall acoustic ‘breathing’around Anna Fedorova’s
piano on her Shaping
Chopin set [Channel Classics
CCS 43621; DSD128] as it
was with the intertwining
instrumentation and driving
rhythm section on Yes’s‘Yours Is No Disgrace’ [TheYes Album; Rhino WPCR80305]. These innovative loudspeakers
can play hard and deliver all the dynamic
impact one could want, but do so with aspeed, control and sheer exuberance that’sfrequently breathtaking, and all the while

KEF’s VP of Technology, Jack OcleeBrown, admitted to going ‘all out’in this redesign of the Blade. Not
only was this an opportunity toincorporate the latest Uni-Q driver,and MAT absorber, but KEF was also
determined to reduce the complexityof the MF/LF crossover, achieve asmoother frequency response atwide horizontal angles and improvethe clarity and precision of basstransients. The midrange driver
excursion capability also needed tobe increased and distortion reduced.
‘Hitting these targets was verychallenging’, acknowledged Jack.
‘We started by refining the motor –trading the single annular steel plate(forming the outside of the gap) fora steel-copper-steel laminate. The
copper layer is right next to thevoice coil, reducing inductance andupper midrange distortion. Also,with the strength of the motor now
more constant over a wider range,
this enhances cone travel and further
reduces distortion.’
This re-imagining of the Uni-Q
motor assembly also gave KEF thechance to better couple the MATabsorber onto the back of the driver.
‘As both the HF and MF magnets
are outside of the respective coildiameters, this gave us plenty ofspace within the coils to optimise
the channel that leads rear-radiatedsound into the MAT disc.’
FEA software was used extensively
in the modelling of the Blade One
Meta’s design. ‘The driver chassis
are designed to flex in a controlled
fashion, decoupling vibrations fromthe cabinet body.’ It’s just one moreinnovation that keeps this flagship
Blade at the cutting edge. PM‘Their sheer
exuberance
is oftenbreathtaking’www.hifinews.co.uk | Reprinted from Hi-Fi News for global distribution

r PMLabreport
KEF BLADE ONE META
LEFT: Two reflex ports serve the upperand lower pairs of bass units. KEF’s split
bass/mid crossover is accessed via two
sets of bi-wire/bi-amp terminals that
may be linked back together via a novel
screw-tight connector

vocals sweet and well-placed. Again
there was effortless soundstaging– without ever distracting fromthe passion of the performance byrevealing the mechanics of what thespeakers are doing.
Meanwhile, Franz Ferdinand’s ‘No
You Girls’ [Hits To The Head, Domino
WIGCD473X] sounded glorious with
its chugging rhythm section andcatchy chorus. The track is big anddense, but KEF’s Blade One Metas
made sense of it, while proving they
can get down and dirty with thebest of them.

While attention is inevitably focused on the efficacy of KEF’s
Meta disc in dissipating the Uni-Q driver’s rear-radiation [seeLS50 Meta, HFN Jun ’21], the Blade One Meta’s driver ensembledelivers a remarkably flat axial response [see Graph 1]. Withresponse errors of just ±1.2dB and ±1.3dB, respectively, coupledwith a precise 0.45dB pair matching (all re. 200Hz-20kHz),the Blade One Meta faces competition from a mere handful ofactive, DSP-corrected speakers [see HFN Apr ’20] in the questfor ‘flatness’. On the other hand, the extreme ultrasonic treble
resonance at 40kHz [+16dB re. mean midband output, pinkshaded area] is specific to the Uni-Q driver, this breakup mode
successfully deferred by a good 10kHz or so courtesy of thedome’s hybrid spherical/elliptical profile. It is clearly visible on
both the forward response and CSD waterfall [Graph 2], thelatter also illustrating the very ‘clean’ and quick decay of mid andtreble – a likely benefit of its Meta technology.
The flat response also makes for an accurate and subjectively
relevant sensitivity of 88.5dB (1kHz) and 88.3dB (500Hz-8kHz),
figures in tune with KEF’s rated 88dB. Bass extension, too, isimpressive at 34Hz (–6dB re. 200Hz), the 46Hz-350Hz (–6dB)
output of the quad woofers combining with the slickly judged
26Hz port tuning [green shaded area, Graph 1]. Bass distortionis also very low at ~0.1% (re. 90dB SPL), but all this performanceis gained at the expense of a fairly tough load, the impedance
modulus dropping to just 2.5ohm/500Hz with max. phase anglesof –57o/22Hz and +52o/1kHz. The toughest ±47o/4ohm regions
occur in the low bass (24Hz) and midrange (840Hz). PM

Enjoyment overload
I think I can safely say I didn’t find atrack I did not only enjoy, but delightin, during the time I spent with theseslender but somehow ominouslooking Blades. They cruised throughthe ever-so-refined piano jazz ofDave Arch and John Parricelli’s True
Colours [Linn CKD 678; 96kHz/24-bit], thanks to that absolute
focus, tight rhythms and superb
soundstage size and depth. And thevery same attributes also served
well John Illsley’s ‘The Mission Song’,
with its reggae-tinged beats, added
horns, and inevitable overtonesof Dire Straits [VIII, 100% Records;
100CD119]. The feeling of a greatband making hugely enjoyable music
is palpable here – taking the magicalsound of the Blade One Meta
loudspeakers beyond argument.

HI-FI NEWS VERDICT

making many contemporaries soundsomewhat leaden by comparison.
Neither does one need to feedthem a carefully curated selectionof oh-so-audiophile recordings tobe struck with just what they cando. ‘My Most Beautiful Mistake’,
from Elvis Costello’s current album[The Boy Named If, EMI CD2047],
sounded like vintage Costello withthe singer front and centre, bandspiky and abrasive, and backing‘Marmite’ industrial aesthetic
aside, the magic of the Blade
One Metas is realised in the sortof focus, imaging and definition
you’d expect of the finest
miniature, but written here into
a big sonic picture without any
compromise. They’re weighty,
fast and more than capable ofshaking your chest without any
slur or bloom. They really must be
heard if you’re shopping at thisprice... or even way above.

Sound Quality: 90%
0-------- 100

ABOVE: Response including nearfield summed bass
drivers/ports [green], freefield corrected to 1m at
2.83V [yellow], ultrasonic [pink]. Left, black; right, red0 dB-90.0-18
1.3-272.7-36-45
200

500

1k2k

5k
10k
Frequency in Hz >>20k

4.0msec
60kHz

ABOVE: Uni-Q tweeter’s HF resonance dominates thewaterfall, but the mid is ‘scrubbed clean’ by Meta

HI-FI NEWS SPECIFICATIONSHI-FI NEWS SPECIFICATIONS
Sensitivity (SPL/1m/2.83V – 1kHz/Mean/IEC)

88.5dB / 88.3dB / 86.2dB

Impedance modulus: minimum& maximum (20Hz–20kHz)

2.5ohm @ 500Hz
14.8ohm @ 19Hz

Impedance phase: minimum& maximum (20Hz–20kHz)–57o @ 22Hz
+52o @ 1.02kHz

Pair matching/Resp. error (200Hz–20kHz)

0.45dB/ ±1.2dB/±1.3dB

LF/HF extension (–6dB ref 200Hz/10kHz)

34Hz / 27.5kHz/28.5Hz

THD 100Hz/1kHz/10kHz (for 90dB SPL/1m)

0.1% / 0.06% / 0.5%

Dimensions (HWD) / Weight (each)

1590x363x540mm / 57kg

www.hifinews.co.uk | Reprinted from Hi-Fi News for global distribution