L3 Pro Dome
Midrange
History
The Legatia L3 Pro’s topology is a departure from
the typical cone-type midrange drivers in the
same size category as produced by Hybrid Audio
Technologies. The L3 Pro was intended to be used
in approximately the same fashion as the other
cone-type 3-inch midrange devices in the Hybrid
Audio product line-up, to give the end-user more
choices for a high-end midrange solution to fit a
variety of potential system designs and mounting
strategy. Naturally, the efficacy of the L3 Pro, as
compared to its sibling cone midrange drivers, is its
sensitivity and ability to be used without a sealed
baffle since the L3 Pro is a tuned rear-chamber
midrange.
Attributes
The Legatia L3 Pro is a 99mm (3.9-inch) “small
format” wide-bandwidth midrange/full-range driver
to compliment both two-way and three-way system
designs, where a point-source midrange and/or
full-range driver is required. The L3 Pro is only 6mm
(0.2-inch) larger than the Stage V Legatia L3V2,
and the Stage VI Legatia L3SE, for many potential
drop-in replacement options.
Body and Flange
The body and flange of the L3 Pro is a similar design
topology and geometry to the L1 Pro tweeter.
The body is an extremely high-quality machined
aluminum design (machined from a solid block
of aircraft-grade 6061 aluminum), and contains a
99mm flange providing for the surface-mounting
of the driver via Hybrid Audio Technologies’ unique
knurled attachment nut technology. The dense
metal structure of the L3 Pro housing helps to
reduce resonances within the body of the driver
for effective reproduction of extremely low music
tones. One main mechanical reason the L3 Pro
approximates a true monopole is the fact that
the flange/body of the driver is solid machined
aluminum, void of interstitial spaces, which
terminates resonances well.
The overall dimensions of the driver are very
amenable for use in the car audio environment,
and in locations typical of the standard “3-inch”
and “4-inch” drivers, or in custom locations at the
discretion of the end-user, boasting a depth of
just 44mm (1.7-inch) (the same depth as the Stage
VI Legatia L3SE and only 1mm deeper than its
Legatia L3V2 counterpart). The body features an
integrated tuned chamber, discussed below, to
allow for mounting of the L3 Pro in a simple baffle
without worry of separating front and back waves,
nor building an enclosure. The rear of the body
propagates diaphragm back pressure into the tuned
chamber to provide adequate communication to
the back of the dome for acoustic suspension and
proper operation.
Housing and Tuned Chamber
In addition to the aluminum body of the Pro-series
drivers, the L3 Pro includes a cast polypropylene
tuned and damped chamber at the rear of the
motor assembly; the damped chamber helps
to reduce backwave distortion and significantly
lower the Pro-series driver’s resonance frequency
to allow it to be used to play tones near its
resonance frequency. The chamber for the L3 Pro
is approximately 20 cm3 in internal volume. A
machined aluminum knurled attachment nut at
the base of the L3 Pro provides optimized clamping
strength to the mounting media, and important
feature for terminating modal distortion at the
mounting baffle.
Motor
The motor of the L3 Pro is paramount to the
performance of the driver, providing for a flat
and wide BL curve (as a learning note, BL is the
equivalent of torque in a car; a car with a flat and
constant torque curve provides much better
acceleration and performance than a car with a
peaky, non-constant torque curve). The BL curve
is flat and extended, yielding 4mm of two-way
linear excursion, resulting in the L3 Pro being
able to accurately track the input signal. Reduced
distortion and greater dynamics are the immediate
sonic benefits. The motor of the L3 Pro includes
an NdFeB magnet to improve restorative force,
compliance, motor strength, displacement, and
power handling. The magnet assembly fully
surrounds the voice coil.
Voice Coil
The voice coil diameter of the L3 Pro is a large
50.5mm (2-inch), which is the proper balance
between size and moving mass in super high-end
mobile audio midranges/full-range drivers. The
voice coil diameter serves several key functions:
elevated power handling, dissipation of heat
(thereby lowering power compression), and
maximizing the size of the magnet assembly for
enhanced motor compliance. The voice coil is
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.
Continued on following page...
Legatia Pro
Speaker
Design
© Hybrid Audio Technologies • Cumming, GA • 770.888.8200
© Hybrid Audio Technologies • Cumming, GA • 770.888.8200
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