I was just reading the PDF on the speaker, didnt actually look it them
From the PDF
The drive unit used in the System 600 monitors is part of the latest generation of
Dual Concentric units designed by Tannoy. Among many others features, this range
of drivers incorporate a dual magnet assembly, ‘tulip’ HF waveguide and injection
moulded polypropylene LF cone.
The design of the HF waveguide has been arrived at by making extensive use of
CAD (computer aided design). It matches the acoustic source impedance at the HF
diaphragm into the acoustic environment, shaping the wavefront as it travels down
from the diaphragm ensuring equal path lengths to achieve a spherical wavefront.
Wavefront shaping begins at the diaphragm surface and, because the compression
ratio can be kept relatively low with this design, the distortions due to air nonlinearities
are minimised. A hyperbolic flare has been chosen for optimum low
frequency performance at the crossover point.
The HF diaphragm is made from aluminium and magnesium alloy, with optimised
shape and thickness providing rigid piston behaviour up to 25 kHz. The diaphragm
assembly is suspended by a precision moulded, inert nitrile rubber surround. Its very
narrow roll eliminates resonances below 25 kHz and provides a very stable and
consistent mounting. The roll form ensures high excursions can take place if
necessary yet provides a fatigue-indestructible assembly.
The HF voice coil assembly incorporates a high temperature copper wire chemically
bonded onto a kapton former fitting onto the outside of the HF diaphragm skirt. The
thermal power handling of the voice coil is greatly increased thanks to its ferrofluid
filled magnetic gap
