Mid-Range - Martin Audio MLA User Manual

MLA System
USER GUIDE
With an efficiency of 104dB @ 1m/2.83V, MLA's Dual Hybrid® LF section has a big advantage. This is 6dB more than 98dB figure
typical of a direct radiator design.
MLA's LF section utilises 2 x 12"(305mm)/3"(75mm) voice coil, neodymium drive units in Martin Audio's trademark Hybrid low
frequency horn configuration. Each driver is front loaded by a hyperbolic horn with a low flare rate, whilst the rear of the driver
is reflex loaded to extend the LF output below the natural cut-off point of the horn. The Hybrid design provides the best of both
worlds - packing a punch that direct radiators cannot compete with and convincingly outperforming the LF extension of similarly
sized, horn-only designs.
The twin LF drivers have separate horns spaced as far apart as possible within the enclosure. This double-source arrangement
significantly improves the directivity control of the LF section down to 150Hz, reducing mid-bass output at the sides and rear of
the array. The LF drivers themselves are very high excursion with forced air cooling to reduce power compression.

Mid-Range

With so much design effort concentrated on the vertical performance of arrays, the horizontal dispersion can sometimes suffer
– particularly in designs that use coaxial, co-entrant or cross-firing midrange arrangements. MLA has completely separate mid
and HF horns and the horizontal off-axis response tracks the on-axis response exactly. Martin Audio has 30 years' experience
developing cone-driven midrange horns, and this experience, together with BEM optimised horn geometry has been put to good
use in the design of the MLA midrange section.
The mid horn of the MLA utilises 2 x 6.5"(165mm)/2"(50mm) voice coil neodymium drivers to produce 112dB @ 1m/2.83V - a
huge gain on the typical efficiency of 102dB for cross-firing direct radiator designs. This is a result of painstaking acoustic and
thermal design, utilising forced-air cooling and a thermally-conductive aluminium housing.
Generally, adding a horn to a cone loudspeaker increases its acoustic output in a non-uniform manner - with the greatest output
in the lower part of the horn's operating band and output tailing off toward that of the cone itself at the upper end of the pass-
band. In MLA's midrange horn, a patented*, toroidal phase-bung is placed between the driver cone and the throat of the horn.
This counteracts the tendency of the horn's frequency and energy response to tilt downwards as the frequency rises.
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