THX ARENDAL, Handbook

Page: 24 / 48

The 6.5” and 8” woofers in the 1723 series are built upon
the same core fundamentals as the the 13.8” subwoofer,
but with application specifi c details changed. The woofer
cones does not have the glass fi bre reinforcement of the
13.8” as it is already stiff enough and the bass material’s
inherent self-damping with its proprietary cone treatment
is chief quality. An entirely bespoke design, the mid-
woofers are optimised to cover a very wide frequency
range from 1500Hz, down to the lowest bass notes without
a hint of cone resonance.
Distortion is closely related to how far the cone and motor
has to move and for a given volume level. Size presents it’s
own engineering challenges and the motor, suspension
and diaphragm all must be delicately balanced to be
able to cover the critical midrange frequencies without
coloration.
We use:
1. CCAW (Copper Clad Aluminium Wire) in the voice
coil, balancing the lightness of aluminium, with the
conductivity of copper.
2. An aluminum shorting ring to reduce inductance,
increase frequency bandwidth and lower distortion,
whilst benefi ting from the greater heat dissipation of
a larger voice coil.
3. Suspension FEA analysed to deliver symmetrical
travel, lowering non-linear distortion.
4. Klippel analysed, lightweight, long fi ber pulp cones,
treated with a custom formulation for inherent self
damping, that remains pistonic through its operating
range and beyond.
5. Voice coil venting to reduce physical and thermal
compression, maintaining a hugely dynamic
response.
Multiple drive units are combined to further reduce
Doppler distortions and augment bass output and power
handling. The result is clean, dynamic, high output
capability, maintaining composure and subtle details.
After thorough optimization and testing (using FEA,
Klippel and other methods) of aluminum shorting rings
with a focused fi eld design, the result is a linear magnetic
fi eld over a wide range of input levels, ultra-low distortion,
low inductance, and very dynamic bass.
Symmetrical suspension consists of critical components
such as the NBR surround, Connex spider, and integrated
tinsel leads. All combined to create very high excursion
capability with an exceptionally linear suspension. Again,
this contributes to high output and low distortion at all
operating frequencies.
Air fl ow venting underneath the dust cap (vents in
cone body) and spider (vents in the basket) is added
for two very important reasons. First, air heat from the
voice coil is forced away with each stroke of the cone
diaphragm. This continuous exchange of air mitigates
thermal compression and increases the woofer’s overall
power handling capability. Second, the airfl ow relieves
asymmetric compliancy and noises (ie, distortion) due to
non-linear compression and rarefaction of air typically
MID-WOOFERS