For what it is worth, I found this the other day on the Audio Note website. see the link and you can sort through this link for more info:
http://sw1xad.co.uk/technology_post/conductor-design-some-comments-on-the-issue-of-importance-of-cables/
CONDUCTOR DESIGN – SOME COMMENTS ON THE ISSUE OF IMPORTANCE OF WIRING
Why cables are so important?
Ideal cable is a zero impedance conductor. Ideally, it would present zero impedance to a music carrying signal. Any serious imperfection of a conductor can only contribute to an impedance mismatch, which is the main issue for the signal transmission. In order to avoid it, the cables must “adapt” themselves to the impedance requirements across the source and the signal receiver. Everything matters when it comes to quality and quantity, whether it is the material of a conductor or the reactance of a complete cable.
Our non-ideal world is full of limitations dictated by the laws of physics. Unfortunately, there are no ideal components in a non-ideal world. Each conductive material has its own sonic character and is characterised by the residual presence of the three main electric properties such as resistance, inductance and capacitance. The combined interaction of these properties is called impedance. Since impedance depends on signal frequency, an impedance mismatch between the source (e.g. CD player) and the load (e.g. amplifier) act as signal frequency filter. All filters modulate signals and cause signal degradation.
In spite of all natural limitations, we should not accept a compromise on signal transmission. The main objective was to create a minimum compromise conductor, which maximises signal integrity and its transfer behavior while minimising the effects of as resistance, inductance and capacitance causing signal modulation or simply a loss of a signal integrity. In transmission line theory terms, we looked to design a conductor that would match the impedances (i.e. minimise the signal loss) between the signal source and the load more closely. After all, the main goal of a cable design is to maximise the signal transfer behavior i.e. minimise the impedance mismatch, overcoming the effects of resistance, inductance and capacitance.
Numerous experimentation with cable designs and investigation into the effect of conductor materials on the quality of reproduction of sound, led us to believe that the material quality of a conductor, its dielectric environment and construction are the most significant factors that affect the signal transmission. Some of the findings can be summarised as follows:
Importance of the conductor material
Every conductive material does have a distinct sound signature. Without going into the debate of personal preferences, we find that pure Silver conductors sound generally more revealing, dynamic and more musical. When pure silver was used as a conductor, everything seemed to sound more magical relative to the copper based materials. Is there any reasonable explanation?
Maybe it is the difference in conductive property across silver and copper material. Silver is a better conductor than copper. Each atom of silver has a higher electron capacity of 18 more electrons, resulting in 6-7% more conductivity relative to copper. While we cannot explain and find it difficult to believe how 6-7% better conductivity of silver over copper makes a significant difference, we also noticed that the larger the amount of silver in the conductor the better the low level musical resolution is.
Silver alloy materials should not be confused with a silver plated copper material, which not only sounds inferior and but also only uses less than 1% of Silver. Electro-plating is a low cost chemical process, where a very thin layer of silver is plated on the surface of copper. It is by miles sonically inferior to the process of physically melting high content Silver with copper.
Insulation around the conductors
What really makes a significant difference, we think is the dielectric or insulation material around conductors. A silver conductor of identical material quality can either shine or sound dull depending on the choice of the dielectric material. There many options here: polyurethane, PVA, cotton, silk, PTFT and many others. Some dielectrics are better with silver and some are worse. If a dialectic material sits to close on a conductive material and there are many conductors in parallel, the capacitance of a cable increases. That is a clearly an undesired effect, which we wanted to minimise. After numerous experiments with cable geometry we arrived at a choice of least compromise: Air -the best real world attainable dielectric. While it is not possible to have a 100% air dielectric we strived to maximise its presence by intentionally making a use of oversized PTFE tubing (up to 5x the conductor thickness). The results speak for themselves. We achieved less capacitance, less distortion, more clarity, resolution, air, and greater dynamics and last but not least the amount of energy unleashed.
On the matter of cable construction
While conductor and insulation materials are crucial to the performance of a signal transmission, the arrangement of these materials is a factor of no less importance. There is almost unlimited number of combinations of choosing the size and the quantity of conductors and ways of how to arrange them. All these choices are different forms of a compromise. Too thin conductors sound excellent in the treble frequency region but usually sound poor in the bass frequency region, while for the thicker conductors the issue is vice versa. On the one hand any conductor twisting is undesirable since it increases inductance and resistance. On the other, paralleling many conductors decreases resistance but paralleling too close and too many increases capacitance too. Using a screen surely has benefits of shielding against RFI and other parasitic radio frequencies but brings a drawback of increased capacitance and reduction of airiness in the sound.
THE SOUND OF COPPER VS SILVER CONDUCTORS
The Sound of Copper vs Silver conductors: an approach by SW1X Audio Design™
Disclaimer: Everything stated below is of generalizing nature. Furthermore, we are assuming that everything else is close to being equal i.e. the geometry and insulation of a conductor of both copper and silver conductors is identical and that the conductors themselves are of similar age.
It is widely acknowledged that different conductor materials tend to have a different sound character despite no apparent differences in how these materials measure in terms of their frequency response. Frequency response is a very crude parameter by its nature which cannot measure all audible, interactive and idiosyncratic non-linearities and other properties. So using it as a main decision making-factor for suitability in audio of a material in question can a bit spurious to say the least. Feel free to replicate following experiment at home. Connect round conductor wires made of 99.99% OFC copper and 99.99% fine silver of identical thickness to a spectrum analyzer and measure their frequency response, consecutively.
The result is, one will find no difference in frequency response between pure copper and pure silver everything else being equal. Surprised?
We think that pretty much disproves the myth that silver alloy conductors are “brighter” or are “thinner on bass” relative to copper because of frequency response differences. The technology or science might not be good at measuring many aspects of sound but frequency response curves of both identical geometry conductors are pretty similar if not identical. Nevertheless, ignoring conductor geometry and other factors for now, there exists a distinct difference of sound when both type of conductors are conducting signals of music.
The main sonic characteristics of pure copper vs pure silver conductors can be summarized as follows:
While copper tends to sound warmer and has more body it is a bit slower and less harmonically rich, silver does exactly the opposite. Silver tends to sound livelier, while offering more clarity and harmonic richness but at the cost of a colder character, thinner and lighter body. The differences in sound are clearly audible in the video clip below. The first sample is reproduced through an interconnect that is made of silver conductors and the second one that is made of copper.
Having crudely summarized the main sound characteristics of copper versus silver sound, one must acknowledge that we may be comparing “apples to pears” as there are many other factors that affect the sound signatures of both materials. Other factors may include : origin & age (new vs old), conductor geometry (round, flat, thickness, etc), insulation (dialectric material type, thickness, distance, etc), treatment & storage conditions (ambient temp, crygenics, annealing etc.), direction (wire drawing, manufacturing process), conductor purity – just to mention a few and many more.
It is difficult to imagine to live with a sound of either type of conductor if copper and silver sound exactly the opposite. It is really a matter of choice of other materials & components and customers preferences. Having said that, copper conductors tend to harmonise better with semiconductors, while silver tends to harmonise better with valves. For example, valves are warm sounding by nature (some are more and some are less depending on many other factors) and a silver conductor are naturally cold sounding conductor. If one combined them both, the sound is way maybe less warm than expected. If one combined valves with copper, the resulting sound may become overly warm and may appear less dynamic. On the other hand, if one combined silver with transistors, then silver tends to reveal deficiencies in linearity of transistors due to its semi-conductive grain structure, which is not ideal for long run listening sessions. Of course one can have a combination of silver and copper wiring as as with valves and transistors but silver and copper materials do not harmonise well together when wired in parallel. If one believes that one gets “the best of both worlds” of copper and silver sound one is mistaken as the resulting sound is characterized by dissonance of copper and silver “siblings rivalry”. There are ways around (as we harmonically combine copper & silver in our SW1X Special product versions and our SW1X AQUA line of cables) but that technique is of proprietary nature.
Now the cost factor- one ounce of 99.99% fine silver can easily cost about 10 times more than of copper. Consequently, cables made of fine silver conductors are not cheap and should theoretically cost 10 times more, ceteris paribus. Of course one can save on the amount of silver one employs in a cable but that comes at the cost of sound since the amount of silver employed is highly correlated with the presence or absence of mid bass. If one saves a bit here then the sounds becomes thin. So the direction of conductors made of fine silver becomes a crucial factor. Wire everything the wrong way and the sound will get even leaner and flatter in the mid bass, which is already a problem with most bare fine silver conductor now days. Does the higher cost justifies the performance of silver conductors? The answer to that question is better left to decide for each person individually as expectations and requirement differ on individual basis. What can nevertheless be said is it is difficult to think of properly designed high-end valve amplification without silver material which complements so well with valve type of sound.
Last but not least, on the account of silver plated copper as a cost effective solution- it is the worst that can happen to a sound of a conductor for the reasons stated above. Relatively thick copper core meets ultra thin (not much above 100 microns) & irregularly covered “silver crust” should ideally be avoided by all costs and means as the silver plating process introduces non-linearities & dissonances in all audible frequency spectrum particularly in high frequencies which are characterized by noisiness and lack of clarity, which tend to cause serious peaks particularly in thinner conductors, no matter how thick the plating is.
Cost factor aside, is not the sound we all after? If copper or silver on their own does and cannot offer the desired qualities, why should we live with the sound qualities of one or the other?
Slawa Roschkow, 03.01.2018
Happy Listening
