| Reprinted from Hi-Fi News & Record
Review Renewed
Energy
The Acoustic Energy AE1
was a classic small speaker;
now it's back in a revised form
 When launched almost a decade ago, the AE-1 was the
first modern loudspeaker to use a bass drive unit with a metal cone in combination with a
metal dome tweeter, some two years or so before Monitor Audio, the other early exponent of
the idea. For quite a long time, the AE-1 defined what miniature loudspeakers could do. It
wasn’t the most famous miniature of course: that honour will always belong to the LS3/5a.
But where the latter practised the gentle art of aural seduction, the AE-1 could be
unnervingly credible. The LS3/5a’s skill has always been its ability to cover its
tracks, but close your eyes with the AE-1 and you could be listening to a big speaker.
Sometimes you wouldn’t hear it as a speaker at all. It was that good.
There were times when its slightly thin balance rankled, and its appetite for
super-amps detracted from its practicality.
The new AE-l costs [$2395] in rosewood (as
tested) or piano black, but is a mere [$1995] in satin black; the optional ST-AE1 stands
cost [$995] a pair.
TECHNOLOGY
The AE-1 125mm bass unit, for the old and
the new AE-1 alike, is based on a spun aluminium cone, which is formed on a lathe, giving
superior mechanical properties (says AE) to pressed cones, and which allows the unit to be
formed with an accurately graduated thickness — thinnest at the periphery, and
thickest at the centre. It is then hard anodised on both sides, in effect forming a three
layer sandwich, another innovation introduced with the original AE-1. Thermally conductive
adhesive between the diaphragm and the coil former gives improved heat dissipation,
reducing thermal compression and improving power handling. The driver is also said to be
more rigid, pistonic and linear than conventional units.
The SEAS tweeter is a ferrofluid cooled
metal dome — magnesium in this case — in thermal contact with the voice coil. A
damped rear chamber helps reduce the fundamental resonant frequency.
Of course things have moved on in the decade since the AE-1
was introduced, and it was decided that the model should be updated to answer persistent
criticisms. There is already an improved but more costly AE-1, the Signature [$4395 in
piano rosewood], which features a new and fully encapsulated crossover, new cabinet
control measures, high purity silver wiring, better socketry and improved cabinet
finishes. When the time came to update the mainstream AE-1 with the Series II, it was
natural to base it on the Signature programme, within limits set by a lower target price.
Among the key design aims were improved
sensitivity and maximum volume levels. The old model sensitivity rating was about 86dBW
(‘on a good day’ I was told), which meant using monster amps to produce useful
volume levels. The Series II is a full 2.5dB more sensitive, which takes it to around 88 -
88.5dB, or close to average for loudspeakers generally, achieved partly with a new 5 ohm
voice coil; the old one was 8 ohms. The tradeoff is that the speaker, which now has a 6
ohm nominal impedance, is a little harder to drive.
The other key change is a much simpler
crossover, borrowed directly from the Signature, replacing the original complex high order
network with one featuring first order (6dB/octave) slopes, and with a simpler, shorter
signal path, lifting efficiency and helping produce a more open, dynamic sound. It is also
fully encapsulated in a heat conductive resin to reduce microphony and improve heat
dissipation, and presumably also to prevent things falling off. The input terminal block
uses biwire 4mm binding posts (the 4mm holes will be blocked in due course in accordance
with the new regulations), and wiring has been upgraded (or downgraded from the Signature
model) to silver plated OFC.
There are few other changes. The cabinet is
based on 18mm MDF stock, with a bonded cement lining, which is thicker at the back than at
the front, which means there are no internal parallel walls to encourage standing waves.
My rosewood pair looked superb and was clearly built to the highest standards. The clip-on
baffle cover, however, is not completely transparent acoustically but removing it exposes
the drive units, including bright metal fixing screws, which would have been better in
black.
SOUND QUALITY
One essential accessory for the AE-1 is a
suitable set of supports. Because this is a genuinely high resolution loudspeaker, even
small changes in the way it is used can have a marked effect on the way it sounds. Forget
about shelves, forget about wall brackets. Get the speakers a good 70cm from the back wall
—more if you have the room — and use tall, rigid stands. Acoustic Energy
themselves make just such a stand in the ST-AE1, a dramatically styled, vertically ribbed
pillar affair, heavy and non-resonant, with captive adjustable spikes on the top platform,
and long carpet piercing spikes on the base. This was the stand I used for this test,
along with an Electrocompaniet EC 1-2 integrated amp, Musical Fidelity F25/F16 pre/power
amp, CD players from Marantz and Wadia, and speaker cables from Ixos and Roksan.
When the original AE-1 was on form, it was
a genuine class act. At its worst, some found it on the thin, bright side, perhaps a side
effect of the original ‘maximum information’ design brief. This is no longer the
case. The Series II mid and treble have been reformed into something more accurate and
neutral. There’s no trace of the slightly edgy top, nor of what sometimes appeared to
be a narrow band, high-Q upper midband suckout. The new speaker is an altogether more
emollient package: polished, with warmth and ‘body’, even a suggestion of grace.
Orchestral string quality, which is always a good litmus test, was ripe, full and
polished.
Despite the civilising tendency, the
corrections have not been taken to excess. There is none of the overt, almost lush warmth
of the LS3/5a, and none of the obvious loss of subtle detail that for me limits the use of
that famous BBC-inspired design when the going gets tough. Fine detail may not be painted
quite as sharply as with the original AE-1, but it is still there. This is one of those
loudspeakers that make it possible to resolve grouped instruments of one kind, even to
tell roughly how many players there are in each group.
The obvious limitations are those set by
the limited low frequency passband. It was only with some Sensaura enhanced stereo
recordings, notably the Kovacevich Beethoven Op.31 Piano Sonatas [EMI] and the Howells Requiem
[United], that the absence of a real sense of acoustic was felt, to an extent spoiling
the three-dimensional qualities of these recordings. It is improbable in the extreme,
however, that any comparable size speaker will do better, as the Sensaura process appears
to rely on the acoustic information that is felt as much as it is heard before it comes
alive.
Despite this, the bass sounds much fuller
than you might expect from such diminutive enclosures, and there is no lack of the richer
tonal colours, or any want of orchestral weight. A typical example is the Bartok Concerto
for Orchestra (Boulez/DG), on which the new AE1 distinguished itself with an image
scale, solidity and sonority that was quite out of keeping with its size. Of course the
bass doesn’t have the capabilities of a really big box, but somehow it always seemed
to go deeper than you would expect. In the end the AE-1 never missed a beat. OK, the
lowest pedal stops are not really the AE-l’s forte (piano certainly, but not forte),
but it’s all there, if slightly more distantly balanced in the lowest registers
than you might otherwise expect. Even piano (Kovacevich again) has a weight and dynamic
quality that suggest a much larger loudspeaker, and excellent, consistent imagery, both on
and off axis.
And this is the clue to the startling
ability of the AE-1 Series II, its enormous consistency and dynamic integrity, which is
the obverse of the coin from the absence of compression referred to earlier. There is
nothing subtle about this: the AE-1 simply goes louder as the input goes louder, and it
does so with more conviction and freedom, and less holding back than other speakers,
especially other small speakers. Only those used to open baffle speakers are likely to be
familiar with this quality, the absence of which is often wrongly identified as something
more mundane, such as boxiness.
CONCLUSION
This is a specialised product which
embodies certain contradictions. It is for example very small, yet it works best with
plenty of clear, open space around it, which militates against its use in the smallest
rooms. The lack of bass grunt is also a factor: its absence cannot be simply written off
in the cause of a better midband or treble. These things said, the Series II AE- 1 is a
revitalised design, never happier than when punching outside its weight range. It is less
demanding than its predecessor, though it still requires a powerful, quality amp, and it
is considerably more civilised, confirming its position at the top of the field. This the
one that sets the standards for other ultra-compacts to follow.
ACOUSTIC ENERGY AE1 SERIES II
Drive units: 1 x 90mm spun alloy diaphragm, hard anodised,
and thermally bonded to the 32mm voice coil, 1 x 25mm magnesium alloy dome tweeter,
ferrofluid cooked and damped.
Power handling: Suitable for use amplifiers up to 200 watts
Impedance: Typically 6 ohms Sensitivity: 88dB/W Speaker
inputs: 2 x 4mm binding posts for biwire operation
Frequency response: 65Hz - 22kHz (±3dB) nclosure
finish: Satin black, piano black, Santos rosewood
Dimensions (whd): 180 x 295 x 255mm
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