 Aerial Acoustics Model 20T Loudspeakers
I vividly remember my first experience with an
Aerial Acoustics loudspeaker. That was the Model 10T, back in 1995. I was equipment
reports editor at Stereophile at the time, and I had just informed Aerial's
designer and principal Michael Kelly that I would not be able to audition the 10Ts and
write a review of them in time for them to be eligible for inclusion in the fall 1995
"Recommended Components" issue. That was a major setback for a struggling
manufacturer, but Kelly, although disappointed, was pretty good about it. "I'll tell
you what," I promised, "I'll set 'em up and listen to them, so we can put them
in Class K (review forthcoming)."
The next morning, I called him the moment I made it into
the office (which was not all that early, since I had listened to the 10Ts into the wee,
small hours). "I don't know how it will be possible, but I will get this review done
in time. I'm not allowed to tell you whether or not I liked 'em, but I have to tell people
about them!"
Actually, Kelly was pretty decent about that, too.
These days, Aerial's a very successful speaker company and
I'm no longer an editor at a high-end "industry bible," but Kelly is still nice
to me. When I attended the Consumer Electronics Show (CES) last January, he sat me down in
the sweet spot of his Musical Fidelity Tri-Vista SACD/kW preamp and amp/Aerial 20T demo
system and played some music -- lots of music.
One other thing hasn't changed: I have got to tell
people about these speakers!
Brightness falls from the air
Although they look nothing alike, the 10T was
obviously a significant design influence on the 20T. The 10T featured a ported bass
cabinet that supported an independently rotating cast synthetic-stone midrange/tweeter
module. That two-piece construction and the head-unit's complexly faceted shape were
precursors to the 20T's rigidly braced, multifaceted, two-piece cabinet. However, the 10T
was a blocky construction that spoke more of utility than fine woodworking, whereas the
20T's angular flares and meticulously book-matched veneers are pure eye-candy.
But the 20T's story lies mostly underneath that fine veneer
(although, as an Arkansas blacksmith once told me, defending his highly patterned Damascus
steel, "Beauty needs no defense").
The vented bass console's double-walled construction
sandwiches a layer of constrained damping material between two 1"-thick MDF walls,
which are thoroughly braced with a matrix of crossmembers. Each 30.2"H by 12.6"W
by 22"D bass console weighs 170 pounds and is rock solid. The console's face tapers
to a beveled 10" width, to reduce cabinet-edge reflections.
The 15.4"H by 10.7"W by 22"D 80-pound vented
tweeter/midrange head is even narrower, and, in addition to a flared taper that reduces
its width, also tapers trapezoidally from base to crown, again to reduce
dispersion-damaging cabinet reflections. Like the bottom cabinet, the head uses
double-wall, constrained-layer construction, but also includes a 2" MDF panel that
separates the drivers from the mid/high crossover network.
The head sports a set of hefty down-facing spikes that nest
in brass cups inset into the bass console's top plate. The bass console and head unit are
connected by short umbilical cables that exit the bottom cabinet at the top plate -- the
combination of needing to carefully position an 80-pound speaker cabinet so the spikes
settle into the cups and having to connect the umbilical dictates that speaker
set-up be a two-person job (and one of those persons better have some upper-body
strength). I wouldn't dream of telling you what to do, but if you buy 20Ts,
"let" the dealer set them up -- or recruit your helper at your gym, as I did.
Clear the air! clean the sky! wash the wind!
 As beautiful and well-built
as the cabinets are, however, what has most audiophiles buzzing about the 20T is Michael
Kelly's choice of a new 4.5" true ribbon tweeter -- a whisper-thin, one-piece,
non-laminated aluminum conductor made by Raven and modified by Aerial with custom damping,
an aluminum waveguide, and a humongous neodymium magnet structure.
The use of a ribbon has proved surprisingly controversial.
When audiophiles learn that I have been listening to the 20T, the first question most ask
is, "A ribbon -- does it really sound good?" This, of course, is because
"quasi-ribbon" tweeters have a reputation for sounding dull and less than
detailed. However, this one, at least as employed in the 20T, isn't dull in that sense --
it's "dull" because it doesn't tell much of a story. It doesn't "sound like
a ribbon" or sound overly detailed or dead or much of anything at all, except what
you're feeding through it. Sorry if that disappoints anyone.
I don't want to appear smug, though. When Kelly first
showed me the 20T in Las Vegas, I asked why he used a ribbon myself. "Because it's a
monster," he replied. "It weighs five pounds and you can't blow it up -- well, I
haven't been able to. And its response is ruler flat to 30kHz. Gee, at 20kHz, you can
listen 45 degrees off-axis and it's only down a few dBs!"
Gosh, then why isn't everybody using them? "Because
they cost almost 10 times the price of a really good dome tweeter."
Oh.
The other driver in the head unit is actually the
revolutionary one: a new, custom-built, wide-bandwidth, randomized carbon-pulp 7"
cone driver sourced from Scan-Speak. The driver is built around a special yoke system,
which is CNC-machined in a single piece from superior-quality steel. It too is costly, but
it provides unusual rigidity and a magnetic field that is powerful and uniform.
The motor for the driver is a copper-clad aluminum voice
coil, wound on a titanium bobbin. Everything about the midrange driver is aimed at
maximizing power and control.
That's important, because integrating the midrange driver
to the ribbon tweeter was tricky, and Kelly needed to use a bigger midrange driver than a
"cookbook" approach to speaker building would suggest. The midrange/HF crossover
point is 3.5kHz, so Kelly needed to keep sensitivity high and added a phase plug to
broaden upper-frequency dispersion.
It seems to have worked.
The bass console contains a pair of Raven-built 9"
bilaminate-damped Mueller cones, with cast-magnesium baskets. The drivers are attached to
long-stroke copper-aluminum voice coils wound around titanium bobbins. Kelly points out
that a pair of 9" drivers moves more air than a single 12" driver -- and are a
lot easier to stop and start.
 Kelly collaborated with
Dave Marshall to produce the 20T's crossover network. Actually, Kelly credits Marshall
with most of the design, which features polypropylene-film capacitors, both large air-core
and high-nickel-steel coils (the former in the head, the latter in the bass console), and
a 24dB/octave parallel-resistor design connected with Teflon-insulated wiring and silver
solder.
Both cabinets feature adjustable controls -- a
three-position woofer control provides two levels of bass boost (centered at 55Hz), while
the head boasts a three-position tweeter control that allows you to tune the tweeter/room
interface to your space and distance from the speaker.
All speaker connections are WBT.
Laser-cut steel stands and heavy-duty spikes facilitate
leveling and assure that the 20Ts are as immobile as a 270-pound monolith can be. Which is
to say, extremely.
That do corrupt my air -- I banish you
I roughly set up the 20Ts about 18" from the side
walls of my listening room and about two feet away from the front wall, facing straight
ahead. Given the speakers' weight, it's a good thing that was a fairly good position for
them. (I only had to move them a few inches farther apart and a few inches back to make
the soundstage click into perfection.)
I used my ever-faithful Nu-Vista CD player as source, and
the Nu-Vista and Blue Circle BC3 Galatea Mk III preamplifiers. I auditioned the speaker
with a quartet of amplifiers: Linn Klimax Twin, darTZeel
NHB-108, Conrad-Johnson Premier Eleven, and McCormack DNA-500. I connected everything with
Audience Au24 interconnects and speaker cables,
as well as my long-term reference Shunyata
Research Constellation Series Aries interconnects and Lyra speaker cables.
I used four different power amplifiers primarily to see how
the various designs and power ratings handled the load represented by the 20T -- which is
a nominal 4-ohm load with a sensitivity of 90dB (dropping below 3 ohms at one point,
which, combined with some extreme phase angles, will tax amps incapable of hefty current
delivery). Each of the amps I auditioned sounded somewhat different from the others, but
all seemed quite comfortable driving the Aerials. But I'm here to tell you that the 500Wpc
McCormack really made 'em sing, so go big, if you have the choice.
Floating like a vapor upon the summer air
Dismiss any misgivings you might have about that ribbon
tweeter. The 20T has lots of sweet, full-bodied, top-end detail. Whether you swoon to
female vocalists, thrill to violin cadenzas, or get off on the string overtones of a
flat-picked Martin D-28 or Gibson F5, the Aerial will give you goosebumps.
Gary Valente's trombone had the properly blatty,
near-squarewave overtones throughout Carla Bley's Looking for America [ECM/WATT/31
CD], which is a lot harder to do than it sounds, since Valente has been known to shred
microphone diaphragms when he points that thing at 'em. As good a trick as that is,
however, the 20T trumps it with its reproduction of Steve Swallow's punchy, upper-register
walking-bass work, which was about as solid as I've ever heard it -- including those
occasions when I've perched in front of the man's bass cabinet.
Of course, that makes it sound like the 20T has a big hole
in the center, but that's only because I was saving the best for last; Michael Kelly's
decision to make his midrange driver do so much work has paid off with a seamless,
completely natural midrange response that is uncannily open and . . . right.
I know, I know -- I was supposed to be describing how good
the tweeter was and then I got all distracted by that music stuff. That's the way the 20T
affected me. I have a hard time talking about the highs, the lows, and the in-betweens
because that's all analytical, and the 20T, like music, is all about directly affecting
your emotions.
That's because what the 20Ts do is serve the music. If it's
there, they let it through -- if it's not, they sure don't add it.
When I listened to David Russell playing Giuliani's Grande
Ouverture, Op. 61 [Telarc CD-80525], I wasn't thinking about the tweeter and the
pellucid snap of Russell's plucked overtones, I was marveling at the beauty of Giuliani's
grand miniature and Russell's effortless musicality -- and his ability to discover the
profundity in beauty that needs no defense. Of course, that's the reaction you're supposed
to have to great music-making -- but I'm an audiophile and a professional reviewer, I'm
supposed to pick things apart.
I consistently found myself unable to do that with the
Aerial 20T. Confusing the map with the territory? Heck, after a few minutes, I couldn't
distinguish the difference between the two. I'd start out intent on critical analysis and
melt into a puddle of subjective effect.
Part of that was that the 20T doesn't sound like a speaker.
It is transparent and holographic -- it disappears, leaving a soundstage that is mightily
convincing, not least because of the speaker's exceptional ability to capture dynamic
nuance.
Yeah, it plays loud, but you should really hear it play soft.
I mean really, really soft -- as in the resolution of Ives' The Unanswered Question
(An American Journey [RCA 09026-63703-2]: The San Francisco Symphony; The San
Francisco Symphony Chorus; Michael Tilson Thomas, conductor.) The Aerials captured that
point where sound stops cleaving silence and melds with it -- where it passes through it
and joins the cosmic infinite.
Oh! I was starting to go into the cosmic infinite
myself, wasn't I? Blame the 20Ts -- they really are that good.
And all the air a solemn stillness holds
However, on this side of the infinite, nothing's
perfect, and as much as the 20T matched my tastes and inclinations, it may not be the
right speaker for you. (It's hard for me to imagine, but there it is.)
Let's start with the obvious: It's big. Not huge --
but at nearly 4’ tall and 2’ deep (45.7"H by 12.6"W by 22"D,
overall), a pair of 'em are definitely a presence in your room. Not a great choice for a
small room -- particularly since the 20Ts benefit from some distance between them and you.
I wouldn't recommend sitting closer than 8' in front of 'em, and I'd urge you to shoot for
10' (or more). Similarly, they also soundstage better with greater distance between them.
Then there's that whole question of driving them. The 20T
is not a completely unreasonable load, but there are a lot of amps that simply won't have
the grunt to do the job. If you stick with Aerial's recommendation of at least 50Wpc,
you'll probably do OK, but high-current amps are better, and high-wattage, high-current
amps are better still. If you want to drive 20Ts with tubes, you'll do well to stick with
stable, wide-bandwidth ultralinear designs, such as the CJ I used -- and avoid microwatt
SE designs, which, for all their charm, just won't cut the mustard.
Then there's the dispersion issue. Not lateral dispersion,
where the 20T is actually sort of amazing, but vertical dispersion. Ribbons are line
sources, and they don't radiate much above or below the location of their vertical array.
The location of the 20T's ribbon is perfect for seated listening, but if you're someone
who listens critically while standing or chooglin' around the room, you'll lose a lot of
the top-end felicities it has to offer.
Then there's the question of deep bass, which my friend and
colleague Michael Fremer found less than convincing below 30Hz. I don't completely agree
with Mikey on this one, but we have different rooms and different systems -- and,
ultimately, different tastes (duh!). In my room, the 20T had all the sock and
wallop I could have asked for.
Have I heard speakers that could go lower? Kind of -- the Dynaudio Evidence Temptations had more pants-flapping
impact at 30Hz than the Aerials, but that's not the same thing as more bottom end.
However, subjectively, the Dynaudios sound as though they dig a little deeper, as a result
of the Aerials' slightly warmer tonal character. If I had to choose between the
two, I'd opt for the 20Ts, which I found more seductive overall. Throw in a pair of Aerial
SW12 subwoofers to bring the two systems to price parity, and the Aerials would win
walking away -- and with a whole octave more bass.
In my room, however, the 20T was completely convincing in
the bass arena, without any augmentation. Then again, I enjoy fast response and agility --
both of which the 20T supplies in spades -- over sheer extension.
There is music in the air
Does it seem as though I'm going out of my way to find nits
to pick with the 20Ts? I suppose I am, simply because I'm so besotted by what this speaker
does so well, which is not a short list. It's good looking, honestly engineered,
re-creates a musical performance with a palpability that is uncanny, and never, ever calls
attention to itself. It can place a world-class classical guitarist in your living room --
or really bring a full-scale symphony (and its hall) home for an after-dinner
musicale. You like hard-edged rock? Well, the 20Ts hammered me one evening with body blows
proclaiming that "Elvis Is Dead" (Living Color: Elvis Is Dead [Epic
EK-46202 CD]) that put all of that band's energy and percussive attack between (and
behind) the 20Ts -- a feat I'd never heard any speaker pull off.
So, for me, the 20Ts are about as close to the ideal
speaker as I can imagine coming (other than that whole tricky
not-being-able-to-afford-them aspect). That doesn't mean they will be your perfect
loudspeaker. But they just might be.
They are certainly contenders, and anybody serious about
owning a pair of state-of-the-art loudspeakers should audition them before contemplating
spending a single penny more, much less two or three times their price.
...Wes Phillips
wes@onhifi.com
Aerial Acoustics Model 20T Loudspeakers
Price: $23,500 USD/pair to $28,000 USD/pair, depending on finish.
Warranty: Three years parts and labor.
Aerial Acoustics Corp.
P.O. Box 81248
Wellesley Hills, MA 02481
Phone/Fax: (781) 235-7715
Website: www.aerialacoustics.com
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