5
The slim, tall, deeply rounded tower’s subtle shape intrigues
the eye while confounding easy description. Though its
top and bottom are both ellipsoids of equal area, they are
distinctly different diametric shapes. The smoothly tapering
column that connects them presents another geometric
paradox: surfaces of ever-changing plane dimensions that
are never found to be in parallel in either axis, yet that cre-
ate a solid form that maintains a consistent cross-sectional
area.
The resultant volume can thus be calculated with perfect
accuracy—a necessity in any loudspeaker design—while its
visible result presents a changing profi le from every angle.
Equally important, this unique vented low-frequency enclo-
sure is inherently vibration-free, and so all but completely
devoid of contributed coloration.
Internally, each of the A7’s three higher-frequency drivers
is acoustically isolated, and each midrange unit exploits a
dedicated sub-enclosure with complete transmission-line
termination. In this fashion the A7 midranges deliver the
totality of their engineered motion and performance, while
eliminating backwave interactions with the forward-radiat-
ing wavefront that would otherwise degrade reproduction.
Needless to say, the Snell I
LLUSION
A7’s arrangement of
midrange and high-frequency drivers is in the “D’Appolito
array” originated by Snell’s chief designer—one of the very
few such genuinely entitled, technically, to the name. Over
the past 20 years countless loudspeakers produced with ver-
tical mid-high-mid driver layouts have claimed D’Appolito
status without any particular technical (or legal) legitimacy.
A true D’Appolito array is a far more sophisticated entity,
whose transducer parameters and dimensions, geometric
relationships, and time-domain characteristics of crossover-
fi lter circuits must all be meticulously calibrated to produce
the intended result: a coordinated wavefront with smooth
and consistent axial dispersion, wide, consistent horizontal
spread over a broad frequency range, and controlled vertical
directivity. The resulting “sound-front” minimizes deleteri-
ous fi rst refl ections from nearest surfaces (fl oor and ceiling),
promotes accurate response with spatial character (polar
responses) carefully targeted for natural, musical octave-
to-octave in-room balance, and maintains maximal clarity,
defi nition, transient accuracy, and dynamic potential, all
with a freedom from coloration that is achievable in no
other way.
Finally, the I
LLUSION
A7 incorporates numerous construction
details whose acoustical value has been effectively dem-
onstrated by numerous Snell antecedents. Its dramatically
radiused front greatly suppresses diffraction, eliminating
higher-frequency refl ections toward the listening zone and
so promoting clarity and defi nition. Its midrange/high-
frequency sub-structure incorporates a precisely machined,
cast-alloy bezel that fi xes the drivers in rigid alignment and
resists any reactive driver motions, inhibiting resonances.
Woofer-mounting construction employs a similar alloy
structure to maintain perfect rigidity and dimensional
accuracy. And of course, each A7 is meticulously crafted, as-
sembled, and fi nished, by hand, in calibrated pairs matched
both acoustically and aesthetically, to the obsessive stan-
dards Snell has long established.
