Home Audio & Video Systems are no different than any other system - natural or otherwise - from the standpoint that they are all subject to the same underlying principles of inter-connectedness and interaction.
In order to address those principles modern science has developed a framework called “Control Theory” (a subset of mathematics) for understanding and applying them. It is Control Theory that lies at the heart of “Control Systems Engineering,” and where possible and practical it is the principles and concepts embodied within the two that we are advocating in our “Zero Resonance” approach to superior product design.
At its deepest levels Control Theory can be extremely complex - as complex as the universe, if you will. But for our purposes there is little value in going to any greater extremes than necessary. All that matters is the reader understands that when it comes to audio and video systems there is virtually always a layer or two of greater complexity than what meets the eye, and it is in those deeper levels where we find opportunity to improve fidelity.
Therefore, in order to make the matter as reasonably easy as possible to understand, we believe the simplest approach is to outline the various parameters affecting product design and performance that we have identified as potential areas of concern:
Very small amounts of mechanical vibration can have a bigger effect on the fidelity of an audio or video system than you might ever imagine. When it comes to the world of electronics we all know that electricity can make things vibrate, but did you know that in a reverse process, vibrating materials can create electricity?
In fact, there can and virtually always is a “back-and-forth” type of behavior where in one moment a small device or electrical component can be set into vibration from the effects of electricity, and then in the next those same vibrations generate new electrical signals that had not previously existed. You can read all about this amazing little phenomenon in the following page:
In any case, whether you are trying to construct a simple cable, electrical circuit or even a complete component that is to be used in a high fidelity system, the artifacts generated by Electrostriction and Magentostriction are generally not good things and best avoided to whatever degree possible. Interesting to note is the fact that such artifacts are a direct consequence of RESONANCE occurring within the vibrating component pieces and/or parts.
The above are all well-documented SCIENTIFIC FACTS, and it would be ideal if it were possible to completely eliminate these undesirable artifacts of MECHANICAL VIBRATION, such that our audio/video system would be that much closer to exhibiting ZERO RESONANCE.
Inductance is an electrical property that is exhibited by a conductor of electricity when electrical current flows through it. Specifically, inductance is the property that limits the rate (speed) at which current is able change directions as it moves through a conductor. As inductance increases, the rate of change decreases. Therefore, low-inductance electrical conductors make for the "high speed" transfer of electrical power.
The effort to reduce inductance also greatly helps to "push upwards" the natural "self-resonance" frequency of the conductor assembly (typically a cable), which is almost universally a good thing in any system. That’s because then the resonant frequency (hopefully in the MHz band) of the conductor assembly is much further away from the system's operational frequency band (audio = 20 Hz - 20 KHz). That then reduces the likelihood of any undesirable interactions between the two. Conversely, when the resonant frequency between any two devices or systems reside near one another, there is a significant increase in the chance that the two will interact in a way that will produce undesirable distortion artifacts.
The above are all well-documented SCIENTIFIC FACTS, and it would be ideal if it were possible to selectively eliminate the undesirable consequences of INDUCTANCE, such that our audio/video system would be that much closer to exhibiting ZERO RESONANCE.
Capacitance is an electrical property that is exhibited by a pair of conductors of electricity when electrical voltage is applied across them. Specifically, capacitance is the property that limits the rate (speed) at which voltage is able change directions across a pair of conductors. As capacitance increases, the rate of voltage change decreases. Therefore, low-capacitance electrical conductors make for the "high speed" transfer of electrical power.
Just as in the case of INDUCTANCE outlined above, the ability to reduce and/or control the capacitance exhibited by a given conductor assembly/cable offers great potential for raising its natural resonant frequency, and thereby reduce any potential interactions with the various system components that it is connected to.
The above are all well-documented SCIENTIFIC FACTS, and it would be ideal if it were possible to control and/or eliminate the undesirable consequences of CAPACITANCE, such that our audio/video system would be that much closer to exhibiting ZERO RESONANCE.
Ideally, we would like to control the “Characteristic Impedance” of our conductor assemblies/cables for minimizing any interactions with other components within the system. We would share more detail as to exactly how this whole process works and what techniques can be used to achieve the desired effects, but then again we aren’t in the business of educating the competition. Suffice it to say, if you know what you are doing you can design a better performing cable by adjusting this and other associated electrical parameters.
”Pseudo-Science” ? - NOT!!!
Upon a “First Order Analysis” the academic engineers out there will tell us that the Characteristic Impedance of a cable intended for use within the audio band (100 KHz & below) is irrelevant, because the associated “Velocity Factor” is essentially instantaneous, at 100%. As such, there are no concerns regarding any signal reflections that might result from an impedance mismatch between the driving stage and the load, like there can be in video and digital data transmission systems. Therefore, parameters such as the Characteristic Impedance of a cable for use in audio applications is totally irrelevant.
Bang! Bang! “Maxwell’s”
Silver Hammer Comes Down
Upon Their Stupid Heads
(Bang! Bang! Maxwell's silver hammer
makes sure their assumptions are dead.)
If we take a little deeper look though, we find that there is a bit more to the story. In fact, it all begins with THE FACT that pretty much ANY “impulse” of sufficient magnitude at the right sub-harmonic frequency is capable of exciting the natural resonant frequency within a given system. Specifically, our primary concern is here that of the various cables being used to transfer audio signals, but the following remains true for any of system. The fact is that to stimulate a simple harmonic oscillator into resonance, the spectral content of said stimulating impulse need not necessarily contain significant energy at the final resonant frequency of the system in order to do so. Rather, the impulse only needs to contain sufficient energy at a sub-harmonic of the system’s natural resonant frequency in order to stimulate it into full-blown resonance.
As an example, think of a metal bell/chime or a xylophone that is being played, or even the “sounding” of a tuning-fork. In most such cases the mallet used to strike the bell or chime is purposefully padded so as to dampen the generation of the unwanted “ting” sound of higher frequency harmonics that would otherwise be created.
Again, a tuning fork is often struck against a padded object like the upholstered arm of a chair in order to assure that it generates only a pure tone that is reasonably devoid of higher harmonics. In all these cases the impulse applied to the object for stimulating it into resonance contains very little, if any, energy at the actual resonant frequency that is ultimately being stimulated by it. Rather, all that is required for stimulation is sufficient energy at some sub-harmonic interval well below the resulting resonant frequency, and “off goes” the resonance… like a bell :-)
So, just as in the example above, the audio signals being reproduced within a system and, in particular, any fast-rising transient signals residing within the highest octaves thereof, may act as effective “impulses” that will then go on to stimulate the natural resonances and/or standing-wave reflections within the system/cable. Again, ONLY sub-harmonics of the cable’s natural resonant frequency are required to cause such an effect.
Furthermore, due to the dynamic nature of the music signals being reproduced within the system, as the music changes the resulting impulses will be repeated at complex intervals in direct relation to it. The effect would be similar to repeated strikes of a mallet against a bell, with the pattern of the strikes seeming somewhat random, but yet still possessing various underlying patterns related to the tempo of the music.
There is More Going On Than
These impulses could be said to represent a form of “Morse Code”-type of sequential “ON & OFF Modulation” of the system’s natural resonant frequency. This would be in contrast to that of an otherwise continuous sine wave being generated, such as that of the “Carrier Signal” commonly encountered in radio frequency applications. In fact, the resulting waveform would actually be virtually IDENTICAL to that of a “Modulated Carrier,” and therein lies the source of our primary concern.
Certainly any resulting resonance from the action described above will be very low in magnitude, but its effects upon the non-linear active components (diodes, transistors, OPAMPs, etc.) that make up the active circuitry comprising the system can and often do act as to “Demodulate” such high frequency artifacts. One example of this phenomenon is when a stereo system will suddenly start reproducing the sound of a nearby radio station, even when no actual radio tuner is connected to it.
We all know that a radio tuner is normally required to receive (demodulate) a radio signal, as otherwise the associated Modulated Carrier frequencies of even low-band AM Radio transmissions reside well beyond the range of human hearing and are therefore inaudible - even assuming that one could actually hear EM radio waves in the first place. Nevertheless, under certain conditions an otherwise typical audio amplifier will reproduce the modulated content (voice, music and other sounds in the audible range) of a radio signal present at the amplifier’s audio Input stage.
Typically, this is a very undesirable artifact of the associated interconnect cables and other system wiring acting as antennae to pick up and convey nearby radio station transmissions to the Input stage of the amplifier. In fact, the proper shielding of cables is typically done for the express purpose of avoiding such contaminating artifacts from being injected into the audio amplifier/system in question. Often a broken cable shield contract is all it takes for such a situation to arise, so in high EM radiation environments it is particularly important to use high quality cables that employ good shielding.
In any case, once the EM radiation is conveyed to the amplifier’s Input stage, “something” must act as a radio frequency demodulator for the audio portion of the radio signal to become audible. Otherwise, the resulting audio signals riding on the HF Carrier Signal would not be audible whatsoever. So what is it that performs this demodulation function?
Quite simply, it is the behavior of some active circuit component (typically a diode or transistor) reacting to the presence of the HF radio signal in a non-linear fashion. Such non-linear behavior is a common consequence of the inability of an electronic device intended to operate only in the audio band being subjected to significant levels of energy that reside well above and beyond its ability to process linearly.
In fact, for a radio receiver/tuner to properly demodulate a radio signal so as to retrieve the desired modulated audio, a non-liner device of some type is purposefully inserted into the associated tuner circuitry. In the earliest days of radio before vacuum tubes were even invented, a simple Galena crystal (lead ore) was commonly used as the non-linear device needed to function as the RF Demodulator. You may have even heard of the metal tooth filings of certain individuals acting as radio receivers, with the audible sound of a local radio transmission able to be heard emanating from the person’s mouth. Once again, it is the non-linear behavior of the metal tooth filing as it reacts to the local HF radio signal that performs such demodulation “magic.”
on the Stuff Down Low
It would seem somewhat unnecessary to even mention, but if one is to assume that such behavior as described above is actually taking place within audio systems and specifically within the cables used to assemble them, then by default the effects would have to be quite low in amplitude, at the very bottom of the dynamic range, and as a consequence generally quite difficult to detect. Otherwise there would be no mystery here and no other logical explanation for certain observed phenomena.
Specifically, there exists a practice that has fallen en vogue recently which involves the doubling-up of Interconnect cables by using common “Y” splitters/adapters. In such an arrangement two cables take the place of one and electrically they are simply joined/wired in parallel using the adapters. This technique was first identified and promoted by Mr. Doug Schroeder, a prominent audio product reviewer, and has since been called “The Schroeder Method of Interconnect Placement.” The method is said to provide significantly superior performance to that of a single cable, regardless of the make and/or model thereof.
In light of the above one can safely make a couple of assumptions here:
As a result of the relatively high circuit impedances typically involved (Output = 50+ Ohms & Input = 10K+ Ohms), the division of the total electrical cable resistance in half when going from one cable to two (typically 1-Ohm to 0.5-Ohm) is almost completely inconsequential in comparison. It is totally unreasonable to believe and illogical to suggest that such a small change in resistance would result in any appreciable difference in sound quality or performance.
Assuming #1 above is true, then apart from the Characteristic Impedance and its associated parameters there remains virtually no other variables left known to science that are even remotely sufficient for explaining the effects of the Schroeder Method.
At this point we come to the highlight of this part of our discussion:
Having identified a commonly known and accepted mechanism of RF Demodulation that spontaneously occurs within electronic components and also a potential source of RF Modulation that can arise within audio cables during their intended use and operation, we have directly shown that the Characteristic Impedance along with the general “out of band” High Frequency behavior of an audio cable CAN, and in many cases most probably DOES, affect the “in band” performance of an audio system.
Hence, efforts intended to reduce such interactions and/or their effects upon the system by the intelligent design of associated system cables and wiring represents a worthwhile and often highly desirable endeavor for the express purpose of advancing audio system performance and the general improvement of system fidelity. In other words…