There was a time, back in the 1980s, when much of what was
novel in loudspeaker design emerged from KEF’s R&D department in Maidstone,
Kent. Odd as this may seem as a way of introducing a new ELAC speaker from
Germany, it’s doubly relevant because the £2600 Adante AS-61 – indeed, the
entire three-model Adante range (not including the ASW-121 powered subwoofer) –
incorporates two features associated with that golden era at KEF: one that has
remained familiar, and a second that has rather declined into obscurity.
GOLDEN ERA Before this sounds like an audiophile pub quiz,
I’m talking about the cone/dome coincident driver array (Uni-Q in KEFspeak) and
the bandpass enclosure, better known as coupled-cavity bass loading. Neither is
classic ELAC fare but the arrival of Andrew Jones as chief engineer has acted as
a conduit for them. He worked under Laurie Fincham at KEF in the 1980s, made
his name at TAD (not least with the CST coaxial driver with beryllium dome and
cone), and is now showing us that designing speakers for the deep of pocket is
not his only talent.
ELAC has made coaxial drivers before, in the form of the
X-JET and X-JET II, but these featured a planar or almost-planar annular
midrange diaphragm surrounding one of ELAC’s pleated-diaphragm Air Motion
Transformer JET tweeters. We saw the first cone/dome coincident driver from ELAC
in Jones’ recent Uni-Fi series – the Adante variant is similar in that it too combines
an aluminium alloy cone with a soft-dome tweeter where the dust cap would
otherwise be, although here the midrange voice coil diameter is increased to
2in. The cone is flared, the flare being chosen to combine with that of the
fixed ring around the tweeter, the shape of the cone surround and the
continuation of the waveguide into the bonded aluminium front baffle to achieve
a smooth expansion (Jones describes it as ‘a blended multi-radius profile’)
which delivers wellcontrolled responses both on- and off-axis. The first cone
breakup mode occurs at about 6.5kHz, 1.7 octaves above the 2kHz crossover to
the tweeter.
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| ELAC Adante AS-61 |
This lower-than-typical crossover point is partly achieved
by equipping the soft dome tweeter with a large surround. A soft dome, here
formed of silk fabric with a coating that optimises its vibrational behaviour,
was chosen as more appropriate to this application than a metal dome. This choice
in turn affected the selection of cone profile as, Jones says, ‘the way a hard dome
matches into a waveguide is very different from a soft dome’. At first glance
you could easily mistake the AS-61 for a conventional three-way design,
although the absence of a port (front, back or exhausting through a plinth)
might puzzle you – surely not a closed-box speaker in this day and age? Indeed
not, for as already indicated, all the Adante models employ coupled-cavity
loading at low frequencies – but with a difference.
COUPLED-CAVITY Cast your mind back to KEF’s Four-Two, Three-Two,
etc, models and you may recall that there was no visible bass driver, all the
bass output being delivered via a large reflex port, with the bass driver(s)
out of sight within the cabinet. Essentially the AS-61 is the same but for two
important revisions. First, an ABR (auxiliary bass radiator) replaces the
radiating port, so the bass ‘driver’ that you see is not a driver at all but a
passive cone. The real bass driver is located within the cabinetbehind the ABR,
with – the second revision – a reflex port connecting the enclosed volume
between the driver and ABR with that behind the driver.
In effect, this arrangement resembles a conventional reflex loaded
speaker with a front-firing port, to the front of which is attached the chamber
containing the ABR. Acoustically, this adds a second-order low-pass filter that
increases the upper slope of the bandpass response, at 200Hz, from second (12dB
per octave) to fourth-order (24dB per octave) – all achieved without electrical
filtering. That is one good reason for elaborating on KEF’s original layout but
there are others, described in the boxout above.
From its dimensions, it’s clear that the AS-61 is a
standmount design, unlike the larger AF-61 floorstander. As the stand can have
a significant impact on sound quality, ELAC offers its own partnering LS30 set
for £520. A single-pillar design with steel top and bottom plates, its hollow
aluminium column can be filled with whatever damping material you prefer
(marble flour being superior to traditional sand). Finally, all ELAC’s Adante
models are available in walnut, gloss white or gloss black finishes.
You’d need a fairly substantial set of bookshelves to house
the Adante AS-61, so our tests in Editor PM’s listening room were conducted
with the aid of the ELAC LS 30 stands. Given room to breathe, these compact speakers
can really deliver the goods – namely a typically decisive and well-balanced
sound.
The whispered vocal on ‘This Woman’s Work’ by Kate Bush [The
Sensual World; EMI CDP 7950782] sounded warm and natural, and then gradually
gained in power as it built towards a hard-hitting note of despair. The piano
playing here has a precise, dramatic tone that drives the song towards the
plaintive chorus, ‘all the things I should’ve said...’, and then the knock-out
punch lands, when the Adante AS-61s gracefully caught the sudden swoop of
Bush’s voice, plunging right down to meet the sudden strike of the double-bass –
deep, rich and dramatic. They proved very effective at revealing the intent behind
the music, and the mournful sense of struggle that drives the song, presenting a
depth and drama seldom found with such modestly-proportioned speakers.
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| ELAC Adante AS-61 |
That ability was no less evident with ‘The Soldier’s Poem’
by Muse [Black Holes And Revelations; Warner Bros/Helium 25646 3509-5]. One of
Matthew Bellamy’s occasional experiments with intricate vocal harmonies, the
song proved to be in good hands with the AS-61s as they balanced the
intertwining layers of vocals perfectly. The lower voices had a rich warmth
that contrasted with the higher, more urgent tones that join in as the song
progresses.
The AS-61s even managed to unravel some details that can get
lost with less precise speakers, including Bellamy’s gentle solo vocal
whispering just below the three-part harmonies. It is, as Freddie Mercury once
sang, ‘fastidious and precise’, yet the sound itself is never cold or
mechanical, and the AS-61s delivered the song with the warmth and intimacy of a
live performance. It was a relaxed, open sound too, and one perfectly able to
fill a big room, despite the compact design.
Continuing with Muse, ‘The 2nd Law’ [The 2nd Law; Warner Bros/ Helium 825646568789] sees the band entering full symphonic rock mode, but the AS-61s coped well with the contrasting styles contained in this near 9m epic. The opening swirl of strings was sharp and urgent, drawing the listener in as portentous, multi-layered harmonies entered the fray, adding to the sense of scale and drama. The AS-61s were not fazed, either, as the piece took its turn into rock, where the deep, electronic keyboards landed with real weight and power, the sound remaining well balanced and never overwhelming the lighter, faster percussion that skims across the surface and leads the song into its second ‘movement’.
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| ELAC Adante AS-61 |
The mood here is more
thoughtful, with the AS-61s once
again producing that clear, precise
piano sound, with the simple, repeated
keyboard phrase underpinned by pulsing
bass. The piece ends with nothing less
than the heat-death of the universe where the AS-61s held on to the last lingering note, and wrung out every dying detail as it dwindled away over the final long fade-out.
LIFE IN THE CITY In
contrast, Freddy Kempf’s recording of
Gershwin’s Rhapsody In Blue, with the
Bergen PO/Andrew Litton [BIS SACD 1940],
is full of life and vigour. The AS-61s
delivered the famous opening clarinet
glissando with a sweet, rich tone and a
relaxed rhythm that unwound like a lazy yawn, capturing the start of the new day in bustling New York City. They revealed all the intricate detail in Kempf’s piano runs, and then picked up the pace as the strident brass woke everything up, accompanied by a crystal-clear clash of cymbals.
The speakers perfectly
navigated the rapid changes of pace,
contrasting the horns’ brash energy with
Kempf’s more delicate keyboard work. And
again, the AS- 61s captured the ideas
behind the music, delivering the final
crescendo with a swirl of driving piano
and one final blare of horns that
illustrated all the chaotic energy of
city rush-hour. It was an imposing and
impressive performance given the AS-61’s compact design, not to mention ELAC’s competitive pricing.
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