| Cable
Design
Geometry and Construction
The geometry and construction of a cable are some of the most important
elements in determining the effectiveness of the final product.
When considering the geometry of a cable, many different, but related
factors come into play. The interaction between the various elements
means that it is very difficult to change one aspect of the cable
and not have it affect something else. Pear Cable considers the
proprietary cable geometry that it has developed for ANJOU interconnects,
including “Perfect Twist” conductor arrangement, to
be one of the most innovative and effective designs available. While
most of the design is proprietary, we can tell you that each cable
(not pair) has 25 separate parts not including the connectors! Of
course having a lot of parts does not necessarily make a cable better
than another cable. We simply want to make the point that a very
unique and effective geometry has been developed for ANJOU that
you will not find anywhere else.
High capacitance is potentially one of the most deleterious properties
of an audio interconnect. The reasons why capacitance can cause
problems are covered in the “Electrical Properties”
section of this article. Every effort was made to minimize cable
capacitance in ANJOU interconnects, and the result is one of the
lowest capacitance interconnect cables in the world. Low capacitance
is achieved through the use of small diameter conductors, large
conductor spacing, and low overall dielectric constants. The trick
is to accomplish all of this without compromising the mechanical
integrity of the cable, or creating other problems.
One of the more popular high-end cable designs available today
from a number of manufacturers employs “Teflon® air
tubes”. The driving force behind these designs is the desire
to create a low capacitance interconnect cable. These cable designs
are a prime example of the wrong way to create a low capacitance
cable! By letting conductors rest loosely inside a tube, several
major problems are created simultaneously. The biggest problem is
that the conductors are now free to move relative to the insulation
and each other. This allows the creation of noise through several
different mechanisms that are discussed in the “Noise”
section. The noise will not simply be random, but instead it will
occur in conjunction with the music, creating unwanted distortion.
In addition to this noise, the lack of a mechanically stable system
means that the cable electrical properties are not fixed. Since
the conductors are free to move within their “air tubes”
they will move every time the cable is flexed or positioned. This
means that when you deploy a pair of cables, each cable will have
slightly different electrical properties, depending upon how the
conductors moved inside the tubes. ANJOU interconnects have been
specifically designed to avoid these problems through the use of
an extremely stable mechanical design.
Finally, the air tubes will promote corrosion of the conductors.
Both silver and copper conductors will corrode in air. Needless
to say, corrosion is not good for the cable performance. ANJOU cables
completely avoid this problem through the use of gold conductors.
More information about corrosion is provided in the “Conductors”
section.
Going back to the capacitance, having more air and less plastic
is one way to lower the capacitance of a cable. However, using “air
tubes” to achieve low capacitance is clearly a bad way to
go. Pear Cable has gone to great lengths to ensure that ANJOU interconnects
have a low capacitance, but are fully mechanically stable. The proprietary
“Perfect Twist” geometry maximizes the amount of air
present near the conductors, but does so in a fashion that ensures
full mechanical support of both the conductors, and the dielectric
material. Again, for more information on why it is so important
for a cable to be mechanically stable, please see the “noise”
section.
In addition to low capacitance and mechanical stability of interconnect
cables, conductor design is very important. Pear Cable uses two
36 gauge, solid gold conductors for its ANJOU interconnects. These
two conductors are arranged in a “balanced” configuration.
While there can be applications where more than two conductors would
be desirable for an RCA interconnect, generally it only adds to
unwanted cable capacitance. Solid conductors are used instead of
stranded to avoid the myriad of problems that can arise from the
use of stranded conductors. At the very least, stranded conductors
provide an unstable mechanical environment which will contribute
to a variety of noise problems. The small diameter of the conductors
is good for two main reasons. It reduces cable capacitance and it
eliminates concerns over skin effect. For a definition of skin effect
please see the “Electrical Properties” section of
this article.
While it is unfortunate that more details about ANJOU cable geometry
and construction cannot be disclosed for confidentiality reasons,
we hope that some light has been shed on the rationale behind the
overall design philosophies. It is important to note that every
single component in ANJOU interconnects has a purpose. The construction
is guided solely by functionality and nothing else. The primary
goal is, of course, the best possible sound quality.
Electrical Properties
This section is intended to define some of the more commonly referred
to electrical properties and the roles that they play in audio cables.
Many people fail to realize that cables have electrical properties
just like any other electrical component in their system. Understanding
these electrical properties is a necessary part of the cable design
process. The statement made by far too many audio companies that
electrical properties do not matter in audio cables is simply false.
Resistance
Electrical resistance is the degree to which an electrical component
resists the flow of current. One of the most basic electrical equations
is the relationship between Voltage (V), Current (I) and Resistance
(R). V=I*R
In analog interconnect cables resistance is essentially unimportant.
The signal traveling through an interconnect cable is primarily
voltage, with very little associated current, due to the extremely
high input resistance of audio components. Any reasonable resistance
will have almost no impact on the signal strength. For this reason,
it is perfectly acceptable to use small gauge wire in interconnects.
For loudspeaker cables, the opposite is true, because they are carrying
large amounts of current with relatively low voltage. This means
that in loudspeaker cables large gauge conductors are essential
to good performance.
Capacitance
Capacitance is the next basic electrical property. It is one of
the most important electrical properties of an analog interconnect.
Strictly speaking, capacitance is the ratio of charge to voltage.
Or in other words, it is a measure of the amount of charge per unit
voltage that an object can reach.
Capacitors can store energy or release it. The higher the value
of the capacitor, the more energy it can store or release. If a
voltage is applied to a capacitor the capacitor will take up energy
based on its capacitance until it is at the same voltage as the
voltage source (assuming the voltage source can supply energy).
Conversely, if the voltage drops below the voltage of the capacitor,
it will release energy until the voltage has again equilibrated.
Because of this very basic property, capacitors fundamentally resist
the change of voltage.
Analog interconnect signals are not very “strong”
in the sense that they are primarily voltage with only a small amount
of current. This makes the audio signal very susceptible to capacitance.
Audio signals are alternating in nature (the voltage oscillates
between positive and negative). The frequency at which the signal
oscillates is the frequency of the sound. The faster the oscillations
occur, the larger the effect of the capacitance.
ANJOU interconnects have one of the lowest capacitances of any
cable in the world. This low capacitance reduces the amount of energy
absorbed and desorbed by the cable as the audio signal passes through
it.
Inductance
Inductance is the final basic electrical property. It is the property
that opposes the change of current in a circuit. The explanation
for the resistance to changes in current lies in the formation of
a magnetic field whenever current flows. The larger the amount of
current, the larger the magnetic field. The magnetic field is a
form of energy. When current begins to flow, the magnetic field
begins to form, which takes energy directly out of the current.
This essentially slows down the increase of current because the
magnetic field must be increased at the same time. Conversely, if
current is decreased, the magnetic field must decrease in size,
which releases energy back into the current flow. This release of
energy means that the current keeps flowing at the higher level
a little longer than it would otherwise.
Just like capacitance delays changes in voltage, inductance delays
changes in current.
As stated previously, analog interconnect signals are composed
primarily of voltage with very little current, and loudspeaker cable
signals are composed primarily of current with very little voltage.
Because of this, inductance is relatively unimportant for analog
interconnects, but crucial for speaker cables. The name of the game
is to absorb as little energy from the audio signal as possible.
Comparing the relative strength of the signal voltage to the signal
current enables a cable designer to focus on the appropriate cable
properties. This understanding is paramount when creating quality
audio cables.
Impedance
Impedance is similar to, but not to be confused with, resistance.
Impedance and resistance both have the same relationship with voltage
and current. That is to say, impedance is the degree to which an
electrical component resists the flow of current. The difference
between impedance and resistance is that resistance is only a valid
term for steady direct current (current that does not have an associated
frequency). If a signal has a frequency associated with it, the
resistance to current flow also has to take into consideration the
effects of capacitance and inductance. This is impedance. If the
frequency of a signal is anything but zero (DC), then the term impedance
must be used instead of resistance. This is primarily an issue of
semantics.
Characteristic Impedance
To understand the definition of characteristic impedance, one must
begin by thinking of a cable that is infinitely long. The idea behind
an infinitely long cable is that a signal propagating down the cable
will never reach the end. If the signal can never reach the end,
then it obviously cannot be affected by what is connected to the
end of the cable.
If a small piece is cut off of the infinitely long cable, the long
section must still have the same impedance because it is still infinitely
long. Now, if the small piece is terminated with a component that
has the same impedance as the infinitely long cable, from an electrical
standpoint, it will look just like the infinitely long cable. Because
the small cable now looks like the infinitely long cable, no information
that is sent down the short cable can be reflected back. This value
of impedance, of the infinitely long transmission line, is called
the characteristic impedance.
The characteristic impedance will vary as the frequency varies.
However, at high frequencies, the characteristic impedance stabilizes
and becomes constant. It is this high frequency impedance that is
commonly referred to as the characteristic impedance.
Making a cable with the characteristic impedance of the component
to which it is attached is extremely important to avoid signal reflection.
This is why digital interconnects should always have the correct
characteristic impedance. However, if the wavelength of the signal
is large relative to the length of the cable, then reflections are
not an issue. This is the case in the audio frequency band. This
is why there is no impedance standard for analog audio connections
or equipment. Even if one wanted to match the impedance, it would
be extremely difficult because the characteristic impedance is changing
with frequency in the audio band. Reflections are simply not an
issue with analog audio.
Skin Effect
The skin effect is the tendency of current to travel on the outside
of a conductor as the frequency rises. The explanation can be derived
from the influences of inductance on the signal. As the frequency
of a signal rises, the magnetic field pushes the current to the
outside of the conductor. As the current is pushed to the outside
of the conductor, the effective cross-sectional area of the conductor
is reduced, which increases the impedance.
The impact of this effect on audio transmissions is that high frequency
information sees higher impedance than low frequency information.
As the signal passes through the cable, this causes the high frequency
information to be absorbed as heat. Obviously this is not a good
situation. However, the smaller the conductor, the lower the impact
of the skin effect. If a suitably small conductor is utilized, the
skin effect can be virtually eliminated.
The very small (36 gauge) conductors used in ANJOU interconnects
are small enough to eliminate any high frequency attenuation concerns.
Don’t buy plated conductors!
Many audio cable companies plate or clad their conductors with
a different metal than the one used in the core. Usually this is
either silver or tin plating on copper. All metals have different
resistivities. Because the skin effect will push high frequency
information to the outside of the conductor, it will encounter the
different metal on the outside of the conductor. In the case of
the silver (which has a lower resistivity than copper), the high
frequency signal sees a lower impedance than the low frequency information.
This will cause a distortion in the relative amplitudes of the high
and low frequencies of the audio signal.
In the final analysis, it doesn’t matter what combination
of metals is used. It is not a good idea to allow the high and low
frequency information of the signal to see different impedances.
The reason why silver and tin plated copper was invented was to
reduce the corrosion rate of the wire. Do not be fooled into believing
this relatively cheap wire was developed for some special audio
application.
Noise
Noise in audio interconnect cables is caused by a variety of phenomena
and can create more damage to audio signals that many realize. When
most people think of noise, they think of random background hum
that simply raises the general noise level. In fact, noise can be
generated in tandem with the music signals, which can have an even
more deleterious impact than random or 60 Hz hum. Pear Cable interconnects
are specifically designed to mitigate all types of noise.
The more commonly considered forms of noise are electric, magnetic,
or the combination of both. When electric or magnetic fields are
formed close to a potential receiver (i.e. the cables) they are
generally considered independently. If, however, the noise is being
generated far away, the two are considered together and called electromagnetic
noise. The source of this type of noise is usually other electronic
components or electrical devices or wiring.
If, for example, a power cord is run next to an audio interconnect,
it is highly possible that the magnetic field produced by the power
cord will create a 60 Hz hum in an audio system. For this reason,
all other system wires should be kept away from audio interconnects.
ANJOU interconnects have a proprietary “Perfect Twist”
conductor arrangement that provides excellent rejection of both
electric and magnetic fields. Because of this, ANJOU interconnects
do not employ a separate active shield. The presence of an outer
shield increases the capacitance of the cable unnecessarily.
The types of noise of greatest concern to Pear Cable are the non-random
types that are generated in tandem with the musical signal. This
non-random noise comes from mechanical vibrations within the cable
itself. It cannot be overly emphasized how important it is to have
a mechanically stable cable. There are at least three separate mechanisms
for movement within a cable to cause signal distortion:
- Triboelectric effect
- Movement relative to an electric field
- Movement relative to a magnetic field
It is important to realize that there are two separate energy sources
for this vibration.
The first energy source comes from the loudspeakers themselves.
As music is played, the vibrations in the air (sound) vibrate “hairs”
in your ears (so you hear the sound), as well as everything else
in the room. This vibration includes your audio cables. This mechanical
vibration, induced by the sound itself, is a major enemy of cable
producers. Unfortunately, this problem is rarely talked about, and
frequently overlooked.
The second energy source comes from the current running through
the audio cables. As mentioned previously, the current will produce
a magnetic field. Since all of the wires in our audio systems have
current running in opposing directions (+ and – lead, this
applies to AC as well) opposing magnetic fields are set up in the
conductors. These opposing magnetic fields mechanically push the
conductors apart, thus causing mechanical vibration. This is a major
design consideration for loudspeaker cables. However, in audio interconnects,
the current is so small, that this effect can truly be neglected,
so we will not elaborate on this second mechanism for now.
What is important about both of these sources of noise is that
they are not random. Both effects are a direct result of the sound
being made by the audio system and are therefore making noise in
sync with the music. As soon as noise is made in sync with the music,
serious distortions become a concern. This kind of distortion is
far more bothersome than random noise, because in the real world
we are always surrounded by some amount of random noise. The finest
concert halls in the world and finest listening environments ever
constructed will always have noise present. In fact, the complete
lack of background noise sounds very unnatural. Anyone who has been
in an anechoic chamber will attest to this fact. Of course, in the
final analysis we go to great efforts to assure that our cables
reject as much noise as possible, but it is important to understand
where the more serious problems lie for audiophiles.
Now that we have established the idea that mechanical vibrations
can cause serious problems, let’s go back to understanding
the three mechanisms.
The triboelectric effect is a familiar phenomenon to most people
(though not by name). When two different materials are rubbed together,
an electrostatic charge builds up, in equal amounts but opposite
charge, on the two materials. This is what happens when a person
walks across a carpet. If the air is dry enough, the person will
build up a charge of literally thousands of volts. When that person
goes to touch a doorknob, a spark will be generated as the charge
is equalized. The ease at which the charge is transferred depends
upon the materials in question. Electrons are literally being rubbed
off of one material and on to the other material. This is a major
problem for microphone cables because they are constantly in motion.
In analog interconnects, as sound vibrates the cables, the conductors
will move differently relative to the dielectric material. As this
happens, the vibration will create electron transfer between the
conductors and the dielectric material. This constitutes a direct
form of distortion, and again, it will happen in sync with the music.
Very bad!
Going now to the “movement relative to an electric field”,
this is another mechanism for causing distortion when a cable vibrates.
Every cable has a certain capacitance. As an audio signal travels
through a cable it is constantly charging and discharging this “capacitor”.
In general, as covered in the “Electrical Properties”
section, it is desirable to minimize the cable capacitance in order
to minimize this effect. The cable capacitance is heavily dependant
on the geometry of the cable. If the conductor of the cable moves
relative to the dielectric, the cable geometry has changed and thus
the capacitance has changed. The change in capacitance means that
charge must be either absorbed or desorbed from the conductor. That
energy will be either added or subtracted directly from the audio
signal, and again it will happen in sync with the music. Of course
the change in capacitance will be small, but the rate of change
can be fast. Rapid changes in charge are rapid changes in current
which will harm the fundamentally low current interconnect signal.
Finally, “movement relative to a magnetic field”,
is a well-known mechanism for creating current. The mechanisms behind
inductance work both ways. That is to say that if current flows
through a wire a magnetic field is produced, and conversely if a
wire is moved relative to a magnetic field a current is created.
Because of this, mechanical vibrations of conductors relative to
the magnetic fields set up by their own currents will cause noise
pick up. While it has already been stated that the current in an
interconnect is too small to create a large enough force between
the conductors to worry about, the vibrations caused by the sound
waves do have the potential to move the conductors enough for this
to matter. Therefore, because of mechanical vibration induced by
the loudspeakers, we must consider this source of noise not just
in loudspeaker cables, but also in interconnects.
How do we solve harmonic noise pickup?
The best way to reduce the amount of harmonic noise pickup is to
ensure that a cable is mechanically sound. Again, loosely resting
conductors in insulating tubes is just about the worst possible
design when it comes to mechanical stability. The proprietary “Perfect
Twist” technology used in ANJOU interconnects was specifically
developed to allow the fabrication of a low capacitance cable that
is mechanically stable. It is important for a cable to not only
be mechanically rigid, but also well damped. Without appropriate
damping, even a “strong” cable will resonate at various
frequencies. Adequate damping will increase the amount of energy
required to vibrate cable components. ANJOU interconnects employ
a braided Kevlar outer layer which is compressed onto the inner
cable structure by the outermost plastic sheath. Kevlar is unique
in its ability to provide an extremely high tensile strength with
flexibility. It is this Kevlar layer which provides much of the
necessary damping force to the final cable.
In addition to the proprietary “Perfect Twist” technology,
and Kevlar/Sheath damping system, special attention it paid to the
cable ends. Of course the connector is simply an extension of the
conductors, so if there is any vibration of the cable relative to
the connector, noise will be generated. The setscrew clamping system
employed on the connectors ensures that a strong connection is made
between the connectors and cable. The final result is a connection
that is as free of problems as the core cable.
From the beginning of the design stage of ANJOU interconnects the
negative effects of mechanical vibration were considered. The final
result is a completely unique cable that is enormously stable and
well damped. How well does your cable manufacturer deal with mechanical
stability?
Materials
Conductors
Just as one might expect, the conductors of virtually any cable
are important to the cable performance. In the case of audio, a
very delicate signal attempts to pass through them without being
harmed. The characteristics of the audio signal determine what types
of materials are best suited for the particular cable in the connection.
In this section, audio interconnects, and specifically ANJOU interconnects,
will be discussed.
In order to select an appropriate conductor material, one must
first understand the signal passing through it. In the case of an
audio interconnect the signal usually peaks in the range of 0.3
– 2.0 Volts. The input impedance of the preamplifier or amplifier
receiving the signal is high, frequently in the neighborhood of
10,000 Ohms. This means that the amount of current traveling through
the cables is extremely small. The interconnect cable, is therefore
transmitting a signal composed primarily of voltage with a little
bit of current. The impact of the conductor material on this signal
will be examined in this section.
ANJOU interconnect conductors are made from pure solid gold. The
primary reason for doing this is to prevent oxidation of the conductor
surface.
All of the most commonly used conductor metals (copper, silver,
tin, nickel) will oxidize or corrode at room temperature in air.
Please note that the primary corrosion of silver at room temperature
is with sulfur, which forms silver sulfide. Silver can also be oxidized
by ozone to form silver oxide, but the primary layer that forms
on silver exposed to air is silver sulfide. Many cable manufacturers
falsely state that the “silver oxide” layer that forms
on their conductors is O.K. because it is conductive anyway. This
is just plain wrong. Silver sulfide is actually an electrolyte,
which allows the movement of silver ions and has actually been proposed
for “atomic switches”. It is not something that you
want on the conductor surface.
In the case of copper, copper oxide forms when metal is exposed
to air. Copper oxide is an insulator, and has entirely different
properties from either the copper, or the cable insulation. A high
magnification Scanning Electron Microscope (SEM) image of an oxidized
copper wire surface is shown in Figure 1.
Figure 1. (see right)
So why does it matter if there is a little corrosion of the conductor
surface?
Due to the inherent low current nature of interconnect signals,
the capacitance of audio interconnects is extremely important. Again,
the details of capacitance are explored in the “Electrical
Properties” section. However, in brief, the capacitance is
most affected by the insulation closest to the conductor. Corrosion,
being directly on the surface of the conductor, is in the most sensitive
area possible when it comes to the capacitance. Surface corrosion
causes general increases in the capacitance as well as non-linearity’s
in the capacitance. Corrosion of interconnect conductors is unacceptable.
Insulation is not a perfect
seal!
One of the popular methods of achieving low capacitance in cables
today is to use insulation air tubes. These designs are clearly
the most susceptible to conductor oxidation or corrosion. They also
have serious mechanical stability problems, which are covered in
the “Geometry and Construction” section. These interconnect
designs should be absolutely avoided.
It is important to understand that all insulation materials leak
air. Even if the insulation is directly in contact with the conductor,
oxygen and other gases will penetrate the insulation and corrode
the conductor. This property of the insulation is known as the “permeability”,
and can be easily obtained from insulation manufacturers. For example,
the permeability of oxygen through Teflon® FEP is 11,600 cm3/m2*24h*atm.
The diffusion of oxygen, or other gases, through the insulation
will be small, but the conductors will oxidize over time.
The gold that Pear Cable uses in its ANJOU interconnects is 99.99%
pure, and is of the finest quality available. The conductors are
custom manufactured for Pear Cable by a semiconductor supplier to
ensure that the highest quality standards are adhered to. Smooth,
defect free conductor surfaces are assured, and the drawing direction
of the wire is used to set the directionality of the cable.
The end result for the conductor material used in ANJOU cables
is a metal that is absolutely stable. Unlike many other cables,
the conductors will not degrade over time. The use of pure gold
delivers overall performance that cannot be rivaled.
Insulation
Cable insulation has a dramatic impact on the performance of any
audio cable. Insulation can be thought of as having two distinct
but intertwined elements; the materials, and the geometry associated
with those materials. This section will deal primarily with the
materials themselves, while the insulation architecture is covered
in the “Geometry and Construction” section.
The primary function of insulation is of course to prevent the
cable conductors from short-circuiting with one another. In order
to do this, insulation must be electrically non-conductive. It is
not difficult to find materials that satisfy this requirement. Beyond
being non-conductive, it is desirable to have insulation that does
not absorb energy. One of the primary measurements of how much energy
an insulation material will absorb is called the dielectric constant.
The dielectric constant has a direct impact on the capacitance of
the cable, which is discussed in detail in the “Electrical
Properties” section. In brief, capacitance describes the
storage and discharge of voltage. When trying to convey an audio
signal through a cable, this storage and discharge of voltage is
a direct form of distortion and should be minimized.
In order to minimize energy storage, it is desirable to have the
insulation dielectric constant be as low as possible. A material
that absorbs absolutely no energy has a dielectric constant of 1.
The only “material” that meets this criterion is actually
the absence of material, or a perfect vacuum. Air is close to a
perfect vacuum with a dielectric constant of only 1.0006. Teflon®
has the lowest dielectric constant of all plastics, which is why
many audio cable manufacturers use it. While there are many different
types and grades of Teflon®, the three most common forms are
PTFE, FEP, and PFA. Although variations will occur depending on
the grade and manufacturing process, the most commonly accepted
dielectric constants are listed in Table 1.
Table 1. Dielectric Constants of Insulation Materials
| Vacuum |
Air |
PTFE |
FEP |
PFA |
Kapton® |
| 1.0000 |
1.0006 |
2.1 |
2.1 |
2.1 |
3.5-3.6 |
PTFE is the original Teflon® formulation, and is the material
employed in Pear Cable products. The three different types of Teflon®
listed in Table 1 all have virtually identical dielectric constants.
This makes them all good choices for audio cables. More importantly,
the dielectric constant is stable over a wide range of conditions.
Unlike most other plastics, from 1 Hz to over 1 GHz the dielectric
constant remains the same. This stability is absolutely crucial
to achieving undistorted audio transmission. Most other materials
have peaks and valleys in the dielectric constant across the audio
frequency band, which causes a plethora of corresponding distortion
problems.
While Teflon® is the best plastic material to use as an insulator,
it becomes readily apparent when looking at Table 1, air is the
best practical dielectric possible. In fact, the insulation of Pear
Cable products is designed in such a way that most of the cable
is air, and Teflon® is only used where necessary. This is known
as the cable architecture, and is covered in the “cable design”
section.
Foamed Teflon® is bad!
There are many ways to create a Teflon®/air insulation structure,
and Foamed Teflon® is one of the more common methods. Foamed
Teflon® is exactly what it sounds like; namely Teflon®
that has air bubbles injected into it. These air bubbles lower the
overall dielectric constant of the insulation. It is commonly used
because the mixture of air and Teflon® can essentially be treated
as one material, making fabrication processes simpler. One of the
biggest problems with this insulation technique is that the overall
dielectric constant is reduced, but the randomness of the bubbles
creates a myriad of local anomalies. Large air bubbles on the surface
of conductors are unpredictable and the associated dielectric constant
variation causes a variety of transmission problems. In fact, it
is well known that this phenomenon slows down data transfer in Ethernet
cables. Foamed Teflon® is never used in Pear Cable products
and should not be used in any high fidelity audio cables.
Kapton® is not better than Teflon®!
Kapton® is a high performance polymer that has a number of
high tech applications, but audio should not be one of them. To
begin with, as shown in Table 1, the dielectric constant is dramatically
higher than Teflon®. This leads to higher capacitance, the
effects of which are discussed in detail in the “capacitance”
section. In addition to being high in general, the dielectric constant
is also variable over the frequency range of audio systems. According
to the manufacturer (Dupont), the dielectric constant for Kapton®
Type HN is approximately 3.54 at 100 Hz and goes down steadily to
3.46 at 100,000 Hz. This means that the high frequency components
of your music would see a different cable, electrically speaking,
than the low frequency components. Not good! However, the biggest
problem with Kapton® is its affinity for water. The manufacturer
clearly states, “Kapton® polyimide film is made by a
condensation reaction, therefore, its properties are affected by
water.” This has a disastrous effect on the dielectric constant
as the humidity changes. Table 2 displays the affect of humidity
on Kapton® Type HN, as provided by the manufacturer.
Table 2. Kapton® Type HN
| Relative Humidity (%) |
Dielectric Constant |
| 0 |
3.0 |
| 30 |
3.3 |
| 50 |
3.5 |
| 80 |
3.7 |
| 100 |
3.8 |
The impact from the humidity is tremendous. This means that if
your audio cables are made using Kapton®, you are literally
listening to an entirely different cable, depending upon the humidity
of the listening room. In comparison, with Teflon® there is
“no measurable dielectric change with humidity”.
Kapton® has its uses in a variety of applications due to its
ability to perform in extreme temperature environments and properties
such as corona resistance, but it should not be used in audio cables.
Pear Cable is dedicated to identifying the best possible materials
for use in our cables. Insulation material is a very critical element
in the overall performance of an audio cable and we have gone to
great lengths to ensure that only the best materials are employed.
Connectors
Do not overlook the importance of having a good connector! While
at first this may seem to be a trivial aspect of an overall cable
design, it is overlooked at one's own peril. There are a numbers
of factors to be considered in the selection of a quality connector.
ANJOU interconnects utilize WBT Topline crimping RCA connectors.
While many manufacturers utilize WBT connectors in their products,
few employ Topline connectors due to the expense. Careful evaluation
has led Pear Cable to believe these connectors to be the finest
available in the world, and thus has included them in the ANJOU
interconnects.
Do your connectors address all
of these issues?
Cold welding is the best way to make a connection between two pieces
of metal. Cold welding is a welding process performed under high
pressure or vacuum without the use of heat. Precision “dies”
and the appropriate amount of pressure allow two separate pieces
of metal to bond on the molecular level. When performed properly,
the resulting joint is gas tight and often stronger than the parent
materials. This is the process used to connect ANJOU wires to a
suitable crimp, which is then connected to the primary plug via
a setscrew. This is superior to resistance welding or soldering
due to the fact that no heat is used. Heat causes unwanted deformation,
and or oxidation, of the associated metals.
Motion is bad!
When you are listening to your stereo or home theatre, literally
everything in the room is vibrating with the sound, including your
cables. This fact is what enables spies to listen to conversations
inside a remote building by focusing a laser on a window. The laser
is used to measure the frequency and amplitude of the vibrations
of the window, which gives them the sound being generated inside
the room. In order to prevent this vibration from turning into sound
damaging noise, it is critical to prevent cable components and connectors
from moving relative to one another. Triboelectric effects as well
as electromagnetically induced currents will cause distortion and
noise in the cables. For more information on these phenomena, please
see the “Noise” section. For this section, it is only
important to understand that motion of the connector relative to
the component, or cable, is bad.
WBT connectors employ a patented collet type locking system to
secure the connector to the RCA jack. This collet system is very
similar to the way that a milling machine holds a cutting tool.
It is the strongest connection available in any type of RCA connector.
This ensures that the connector will not move relative to the component.
On the other end of the connector is a precision-machined setscrew.
Far more robust than the setscrews used on many competing connectors,
this setscrew can be used to clamp the end of the cable tightly.
In addition to the setscrew, ANJOU cables employ a final heatshrink
jacket to further dampen any vibrations or movement between the
cable and the connector.
Finally, like the cable to which it is attached, the WBT Topline
connectors use only the finest materials available. German engineered
with high copper alloys, multi-layer gold plating, and Teflon®
insulation, performance is assured.
A high quality cable is nothing without a good connection. How
do your connectors stack up?
Manufacturing Quality
Any cable design is only as good as the manufacturing process that
produced it. Cable design can be optimized and the best materials
in the world can be selected, but if the design cannot be reliably
produced, the effort is for naught. Pear Cable is dedicated to ensuring
high precision cable fabrication.
Do not purchase handmade cables!
The audio cable industry has a relatively large number of small-scale
manufacturers. Unfortunately, many of these manufacturers make their
cables by hand. Handmade cables simply cannot match the repeatability
or precision of cables made by machine. Handmade is something to
look for when buying a piece of art, not an electrical component.
All Pear Cable ANJOU cables are made on precision custom designed
machines.
The unique design and geometry that was developed for ANJOU interconnects
does not lend itself to being manufactured on conventional cable
equipment. Because of this, Pear Cable designed and built its own
equipment from scratch. While developing custom machinery represented
a significant investment to Pear Cable, there is simply no other
way to ensure a quality product. This proprietary equipment enables
the “Perfect Twist” geometry to be produced.
Once an overall cable architecture has been identified, the product
enters the engineering phase. From the beginning of the engineering
phase through the development of the manufacturing equipment, everything
is designed using state of the art Computer Aided Design (CAD) software.
The equipment has been designed to hold critical elements such as
conductor spacing to within +/- 0.001”. This level of accuracy
is necessary to ensure that the manufactured cable meets the design
spec, and that every cable is reproduced in a repeatable fashion.
When considering the purchase of a new cable, think about the stability
and accuracy of the manufacturing process. How concentric is the
conductor relative to its insulation? If a product consists of many
tubes or conductors, how accurate is the spacing between the tubes
or conductors? How many twists or braids are there per meter? How
much variation exists between each twist or braid of the conductor?
What will happen when I bend the cable? How well controlled is the
diameter of the conductor? These are all valid questions to be asking
a cable company. In the case of loose conductors within a tube,
was the design intent to have both conductors as close together
as possible or as far apart as possible within the tubes? Both conditions
are possible if the conductor is not fixed. How will the different
positions affect the sound? Ask questions and do not accept misdirects
for answers.
ANJOU interconnects are specifically designed to address all of
the issues listed above. Conductor spacing, insulation spacing,
and general alignment are all held to tight tolerances. It would
not be possible to do without machinery.
We hope this information has been useful in furthering your understanding
of audio cable technology. If this foray into audio cable science
has not fully satisfied your curiosity, please feel free to contact
Pear Cable directly.
Download a pdf Version of "Cable
Design"
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