Fostex NF-1 Technical White Paper page 7

B) Enforcement material A: Carbon fiber of
a super high elasticity modulus
Cases abound where carbon fibers are used for
cones. The carbon fibers contained in NF-1 cones
combine the property of super high elasticity
modulus working as an enforcement material. With
propagation speed of 16,000 m/s, equal to that of
diamond, they allow for higher sound velocity and
more preferrable modulus of flexural rigidity.
C) Enforcement material B: Super-fiber, PBO
(poly- -phenylene benzooxazole)
20,000
10,000
9,000
8,000
7,000
6,000
5,000
4,000
3,000
2,000
1,000
Physical properties of diaphragms
(propagation velocity/internal loss)
Al
Ti
0.001 0.002 0.003 0.004 0.005 0.006 0.008
Internal loss (tan )
a family of aramid fibers.This fiber, used in
combination with the enforcement material A, with
a strength 2 times that of previous aramid fibers,
adds flexural rigidity and permits substantial
improvement in rupture resistance.
D) Enforcement material C: Pearl mica
Attainment of ideal diaphragms is impossible
without success in getting elements which raise
propagation velocity well balanced, with high
internal loss maintained. Pearl mica allows for
Diamond
Boron
Be
Ceramic carbon
Aramid/epoxy
Mg
Aluminum
honeycomb
Shirakawa pulp
Hard polyvinyl
chloride
0.02
0.01
- 7 -
Optimum performance
Carbon graphite
Aramid honeycomb
Biocellulose gel sheet
Biocellulose of sea squirts
PPTA
PP graphite
Polyethylene foam, glass cloth
Delta olefin
PP (polypropylene)
Polyethylene
0.05 0.06
0.03 0.04 0.08 0.1