Speaker Design: Background and Parameters
The most logical place to begin the Legatia L3 user’s manual is to highlight its features, design
considerations, and parameters. Once an understanding is gained as to why the speaker was
built the way it was, and why certain materials were used in the physical construction, the
better prepared the installer will be when it comes to installation, set-up, and tuning of the
Legatia 3” wide-bandwidth drivers.
Speaker Design Considerations (Introduction)
The Legatia L3 is an electrodynamic driver that is comprised of a diaphragm (cone) that is set
in motion by a motor system that has both electrical and mechanical components. The
Legatia L3 is made up of four fundamental and inter-related systems: the motor (voice coil, T-
yolk, front plate, and magnet); diaphragm (cone and dustcap); suspension (surround and
spider); and the speaker frame/basket.
The Motor
The motor of the design is a very complimentary design which utilizes a 1" voice coil, ferrite
magnet, and a unique T-yolk to improve the speaker's nominal and thermal power handling.
One of the main tenets of the design of the Legatia L3 is its over-sized voice coil; the larger
coil provides for improved nominal and thermal power handling. The voice coil was attached
to the voice coil former, which was in turn attached to the inside edge of the speaker cone.
The former aids in transfer of heat away from the coil into the T-yolk, which also improves
power handling. The thermal power handling for the Legatia L3 driver is 50 watts with 3 dB of
power compression without a crossover, and up to 200 watts with a crossover. In the non-
crossover testing sequence mode, our power testing of this driver was performed by using
pink noise from 20 Hz to 20,000 Hz, with the L3 tested in “free air” for eight hours. In the
crossover testing sequence mode, our power testing of this driver was performed by using
pink noise from 250 Hz to 20,000 Hz, with a fourth order (24 dB/octave) highpass crossover at
250Hz, and with the speakers once again tested in “free air” for eight hours. While this is a
rather conservative test, we feel as if it is representative and realistic power handling ratings
and approximates “real-world” conditions and the anticipated use of this driver as a dedicated
midrange transducer.
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 L3 boasts an impressive 2.6mm
one-way linear excursion (Xmax), one of the highest commercially-available Xmax ratings for a
true 3” driver.
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