Features of the SILMIC Series
The "SILMIC" series of
aluminum electrolytic capacitors for acoustic applications
uses an entirely new type of electrolytic paper.
The primary constituent of the newly developed electrolytic
paper is silk fiber. This paper was believed unfathomable
as an aluminum electrolytic capacitor. The new product
beats the silk fiber and mixes it with Manila hemp
fiber to provide an aluminum electrolytic capacitor
used for high-grade music. Therefore, the series
exhibits a superior acoustic characteristics.
It is well known that silk
is spun by silk worms. Since silk is an animal product,
the primary constituent of the fiber is protein.
Normally, the vegetable fiber (Manila hemp or craft
pulp) used in normal aluminum electrolyte capacitors
has a cellulose base material. Simultaneously, this
gives different shape and different characteristics
of the fibers.
For example, normally when paper is wrinkled,
it produces an exciting sharp crisp sound.
Manila hemp paper is quieter than craft
paper, but still makes a fairly loud rustling
sound. These sounds are mainly the result
of hardness of the cellulose fiber. In
contrast, paper made from 100% silk fiber
is extremely flexible and there is absolutely
no hint of any rustling sound.
When we look at these types of physical
properties, the limit of elongation is
between 1.9 and 3.9% for cellulose, with
a tensile strength between 4.9 and 6.4
gram weight per denier. In contrast, the
limit elongation ratio of silk is 7 times
as high at 20 to 23% while, conversely,
the tensile strength is weaker at 3.6 to
4.1 gram weight per denier.
In silk, the fiber-like protein called
fibroin is enclosed in a protein surface
layer known as sericin. Because these proteins
are primarily from glycine, alanine, and
serine amino acids, they have extremely
simple structures when compared to other
natural fibers. Moreover, the fiber surfaces
are smooth and in the axial direction.
Also, the fibers have long and well-defined
crystalloid polypeptide chains.
As described above, silk is extremely soft
when compared to cellulose and is remarkably
better when it comes to resistance to physical
shock -- in a word, silk fiber can be described
The Sound-improving Effect of Incorporating Silk Fibers
At Elna, we have moved
forward with development activities based on the
perspective that this "softness" of silk can mitigate
vibrational energy, which is generated from the electrodes
in the capacitor. Also, this silk softness will mitigate
the vibrational energy of the music propagating through
the air and striking the capacitor. Ultimately, the
softness will mitigate the mechanical vibrational
energy that comes from transformers or rotating systems
within the final product.
As described above, silk is not mechanically
strong. Therefore, we arrived at a feasible
product through mixing the silk fiber with
the Manila hemp fiber. In this mixed paper,
the fibroin is extracted alone in the silk
fiber beating process. Although it is broken
down into fine fibers during the process,
the silk fiber becomes far finer and softer
than even the individual silk fibers. Thereby,
splitting into long thin protein chains.
The raw fibers have diameters between about
10 and 15µm for both the silk and
the Manila hemp. The diameters are reduced
to about 0.2 to 2.0µm in the beating
process because the mixing is allows paper
to blend with the silk fibers by filling
in the gaps (between about 20 and 50µm)
between the Manila hemp fibers. (See the
From the vibration absorption perspective,
this structure is entirely ideal.
Due to the increase in surface area at
the interface between the electrolytic
paper fibers and the electrolytic solution
used for driving the device, we also discovered
an increase signal propagation speed (the
ESR is reduced). For example, the ESR at
1kHz in the GBL electrolytic fluid for
a given thickness and density ended up
approximately 20% less than for the separator
paper made from Manila hemp alone.
Except for the electrolytic paper, we used
the exact same materials and conditions
to produce a 63V 15000µF block-type
capacitor and a 50V 1000µF radial
lead-type small-footprint capacitor. When
these were subjected to aural evaluations,
the high range peak and midrange roughness
were reduced substantially. Also, the low
range richness and power were increased
in the obtained high-quality sound.
In the "SILMIC" series, we also use anode
growth foil with more unetched parts and
a 55µm low multiplier high-purity
cathode foil in order to improve the signal
propagation. Through a synergistic effect
with the characteristics of the silk, we
have made it possible to produce a powerful,
yet-mellow, sound that was not possible
in the past by using aluminum electrolytic
Manila hemp: 100% x 1000
Silk: 70%, Manila hemp:
30% x 1000