Hybrid Audio Technologies Legatia SE - Manual (Page 7)

Legatia SE User’s Manual ©Hybrid Audio Technologies Page 7 of 73
compliance. The voice coils used in all Legatia SE designs are high-purity aluminum, which is
superior to copper for heat dissipation, as well as significantly reduced moving mass. The result is an
extremely light weight winding with good power handling and low inductance.
How much amplitude a speaker can reproduce depends on the volume of air it excites without
overheating. The volume of air that a speaker excites is determined by the surface area of the cone
and the excursion capability of the motor system. Xmax is defined as the width of the voice coil that
extends beyond the front plate, and relates to how far the speaker can move in either direction
without appreciable distortion. The Legatia SE designs boast exceptional one-way linear excursion
(Xmax).
Phase Plug and Shorting Cup
All Legatia SE midrange and midbass drivers come equipped with a phase plug pole piece extension
at the center of the cone. The phase plug is aluminum and, by design, ensures enhancement of the
total inductance profile, providing much of the inductance reduction benefits noted. The phase plug is
plated with rose-tinted copper, which by design does not negatively reduce eddy current, and adds
thermal dissipation potential. The phase plug extends well down inside the pole vent, and acts as a
very large and efficient heatsink for any heat that radiates into the pole. The highest frequencies of
audio emanate from the area around the center of the cone and the lower frequencies are produced
by the area of the cone that is farther from the center. The phase plug pole piece extension improves
the performance and clarity of all Legatia SE midrange and midbass designs by deflecting delicate
midrange and treble tones forward of the driver, while minimizing distortion and improving bandwidth.
All Legatia SE midrange and midbass drivers use copper shorting cups. The shorting cups consist of
an optimally sized and placed cup of copper (Cu) to create a total inductance profile that is not just
low, but flat over stroke, frequency, and power. Inductance is the number one limiter of high
frequency extension and modulation of inductance with stroke, frequency and power, and is the
primary source of intermodulation distortion (IMD).
Cone
The shape, weight and strength of the Legatia SE midrange and midbass cones relate directly to the
extended frequency response of the Legatia SE range of drivers (in concert with the extended phase
plug pole piece, noted above). The Legatia SE cones are concave-shaped hybrid paper diaphragms,
described below. Convex shaped cones, typical of “dome” midranges, typically exhibit “peaky”
frequency response, so we opted instead on a concave cone topology for the resultant smoother
frequency response. And contrary to common belief, most convex cones have a narrow directivity
pattern. The concave cone of the Legatia SE midrange and midbass drivers have a wider directivity
pattern, and are excellent for use in “off-axis” applications.
You will find no composite or metal cone materials used in any Legatia SE midrange or midbass
driver. Our approach to point-sourcing is to allow the Legatia SE midbass/midrange drivers to
effectively play into treble frequencies; having virtually all imaging cues emanating from one set of
drivers in an installation ensures stable stereo imaging across the fundamental frequencies which
define image placement and definition. The Legatia SE midrange and midbass drivers include a
proprietary hybrid paper diaphragm with extremely low moving mass. Paper is widely acknowledged
as the best-damping material, as it provides the near optimum balance of strength and weight. The
paper cone is critical to tame unwanted cone modes, resonances, and the classic “cone breakup”