Science that explains why we hear differences in cables?


Here are some excerpts from a review of the Silversmith Audio Fidelium speaker cables by Greg Weaver at Enjoy The Music.com. Jeff Smith is their designer. I have not heard these cables, so I don’t have any relevant opinion on their merit. What I find very interesting is the discussion of the scientific model widely used to design cables, and why it may not be adequate to explain what we hear. Yes it’s long, so, to cut to the chase, I pulled out the key paragraph at the top:


“He points out that the waveguide physics model explains very nicely why interconnect, loudspeaker, digital, and power cables do affect sound quality. And further, it can also be used to describe and understand other sonic cable mysteries, like why cables can sound distinctly different after they have been cryogenically treated, or when they are raised off the floor and carpet.”


“One of the first things that stand out in conversation with Jeff about his cables is that he eschews the standard inductance/capacitance/resistance/impedance dance and talks about wave propagation; his designs are based solely upon the physics model of electricity as electromagnetic wave energy instead of electron flow.


While Jeff modestly suggests that he is one of only "a few" cable designers to base his designs upon the physics model of electricity as electromagnetic wave energy instead of the movement, or "flow," of electrons, I can tell you that he is the only one I’ve spoken with in my over four decades exploring audio cables and their design to even mention, let alone champion, this philosophy.


Cable manufacturers tend to focus on what Jeff sees as the more simplified engineering concepts of electron flow, impedance matching, and optimizing inductance and capacitance. By manipulating their physical geometry to control LCR (inductance, capacitance, and resistance) values, they try to achieve what they believe to be the most ideal relationship between those parameters and, therefore, deliver an optimized electron flow. Jeff goes as far as to state that, within the realm of normal cable design, the LRC characteristics of cables will not have any effect on the frequency response.


As this is the very argument that all the cable flat-Earther’s out there use to support their contention that cables can’t possibly affect the sound, it seriously complicates things, almost to the point of impossibility, when trying to explain how and why interconnect, speaker, digital, and power cables have a demonstrably audible effect on a systems resultant sonic tapestry.


He points out that the waveguide physics model explains very nicely why interconnect, loudspeaker, digital, and power cables do affect sound quality. And further, it can also be used to describe and understand other sonic cable mysteries, like why cables can sound distinctly different after they have been cryogenically treated, or when they are raised off the floor and carpet.


As such, his design goal is to control the interaction between the electromagnetic wave and the conductor, effectively minimizing the phase errors caused by that interaction. Jeff states that physics says that the larger the conductor, the greater the phase error, and that error increases as both the number of conductors increase (assuming the same conductor size), and as the radial speed of the electromagnetic wave within the conductor decreases. Following this theory, the optimum cable would have the smallest or thinnest conductors possible, as a single, solid core conductor per polarity, and should be made of metal with the fastest waveform transmission speed possible.


Jeff stresses that it is not important to understand the math so much as it is to understand the concept of electrical energy flow that the math describes. The energy flow in cables is not electrons through the wire, regardless of the more common analogy of water coursing through a pipe. Instead, the energy is transmitted in the dielectric material (air, Teflon, etc.) between the positive and negative conductors as electromagnetic energy, with the wires acting as waveguides. The math shows that it is the dielectric material that determines the speed of that transmission, so the better the dielectric, the closer the transmission speed is to the speed of light.


Though electromagnetic energy also penetrates into and through the metal conductor material, the radial penetration speed is not a high percentage of the speed of light. Rather, it only ranges from about 3 to 60 meters per second over the frequency range of human hearing. That is exceptionally slow!


Jeff adds, "That secondary energy wave is now an error, or memory, wave. The thicker the conductor, the higher the error, as it takes longer for the energy to penetrate. We interpret (hear) the contribution of this error wave (now combined with the original signal) as more bloated and boomy bass, bright and harsh treble, with the loss of dynamics, poor imaging and soundstage, and a lack of transparency and detail.


Perhaps a useful analogy is a listening room with hard, reflective walls, ceilings, and floors and no acoustic treatment. While we hear the primary sound directly from the speakers, we also hear the reflected sound that bounces off all the hard room surfaces before it arrives at our ears. That second soundwave confuses our brains and degrades the overall sound quality, yielding harsh treble and boomy bass, especially if you’re near a wall.


That secondary or error signal produced by the cable (basically) has the same effect. Any thick metal in the chain, including transformers, most binding posts, RCA / XLR connectors, sockets, wire wound inductors, etc., will magnify these errors. However, as a conductor gets smaller, the penetration time decreases, as does the degree of phase error. The logic behind a ribbon or foil conductor is that it is so thin that the penetration time is greatly reduced, yet it also maintains a large enough overall gauge to keep resistance low.”


For those interested, here is more info from the Silversmith site, with links to a highly technical explanation of the waveguide model and it’s relevance to audio cables:


https://silversmithaudio.com/cable-theory/


tommylion
The wave travels through the conductor. How is the interaction to be controlled or, by implication, minimised. He doesn’t say.

@clearthinker
https://www.merriam-webster.com/dictionary/skin%20effect

Materials and geometry of the conductors and dielectric are what he uses.
Jeff Smith’s cable are very good, and audibly so. The obvious lack of solder in the signal path, is a consideration that should be taken into account as well (it is less conductive).

Capacitance is another consideration, especially when using ribbon conductors, by separating the conductors so that they are not perfectly parallel alleviates this phenomenon.

There is always an electromagnetic field around, outside the conductor with an alternating current. This is simply understood after a little research into how AC transformers work. This technology is how voltage and amperage can be altered by using different windings, utilizing these magnetic fields I am mentioning.

That there is a magnetic field rising and collapsing around an AC current flow, is also a reason to consider using cable risers, air is a great insulator that will not affect the signal as much as many other materials, like concrete or carpets.


I know Jeff and we have had several conversations regarding cable design. He does have unusual ideas about cable design. I have heard cable shootouts pitting his cables against other top performing cables. There is always some in the room who like his design work and some that don't.

Classes in physics and engineering are only introductions into information which can be used to design cables based on a series of theories and they do not account for what is known as an "error" between design and test data. This design information is good for designing cable in large quantities, it has limitations when you are looking for cutting edge performance. This fuels the search for a better theory.

The problem with book learning is, it is democratic and as such has a tendency to make mistakes. In one case I know of, take hundreds of years to correct the mistake even though the correct answer was known for the same period of time! The book "A round the World in 80 days" makes fun of this issue. So when people tell me (an engineer) "follow the science" it is hard to contain the laughter.

My cable design work will be in a couple or rooms (303 & 307) at the Capital AudioFest. I distribute through Audio Union
This discussion is absolutely the greatest example of a “first world problem”. It’s like watching a tennis match. 
Once again, every electron I ever interviewed has told me that they prefer cables that work rather than ones that do not.  By work, they mean no cuts between the beginning of the wire and the end.

Cheers!
I am done with all this. I buy a cable and compare it with others and if it sounds better I keep it and if it doesnt I sell. The fact that it is is now enough for me. Sometimes this process takes hours to days.