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op48no1

[Sunday, 05-06-2012]
PLEASE NOTE: The following article is a work of satire. Many or most of the facts and opinions presented in the article are deliberately false or distorted. Why did I write this article? For no reason in particular. It is intended to be humorous, nothing more or less. The reader is encouraged to come to whatever conclusions he desires after reading the article.
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It occurred to me that with all the misunderstanding on the forum about Modern tube amp design, it might be a good idea to post a primer on the important subject of Modern Physics. My goal is to give the non-technical reader an overview of the basic concepts of Modern Physics, show how these concepts are relevant to tube amplifier design, and then to discuss what this means about the relationship between science and audio engineering in general.
Up until the early 20th century, science was governed by the principles of Newtonian physics. Newtonian physics is a very good, very practical description of the behavior of matter and energy at the macroscopic scale, which is to say at the relatively low energies and ordinary dimensions that we observe in our daily lives. In the last century, as scientists began to explore the bizarre and often counter-intuitive realm of subatomic particles, it became apparent that matter and energy behave very differently at high energies and over very small distances. Thus the field of Modern Physics was born.
Modern Physics is relevant to audio design because, by definition, audio designers are concerned with information at the finest possible levels of detail. The traditional models of electrical engineering (standard circuit analysis: resistors, capacitors, and inductors in other words) stand directly on Newtonian assumptions. What is not taught in the undergraduate EE curriculum is how these circuit models increasingly deviate from real-world behavior as the resolution of measurement tends toward the microscopic. The higher the degree of resolution required, the greater the error in the standard models, until we reach the point that traditional circuit analysis is wholly invalid and circuit behavior can only be modeled accurately in terms of quantum field theory.
What this means to electrical engineers who wish to advance the state of the art in audio design is that they must learn to look beyond their traditional training and learn to think unconventionally. This is not to say (as some have asserted) that engineering is incompatible with hi-fi design. But it does mean that we should be extremely skeptical when an engineer declares flatly that obvious (to us) subjective phenomena are "impossible" because they "violate the rules of science."
To begin, I would like to go over several very important laws of Modern Physics that will guide us in our Modern amplifier design quest. I will try to explain these as simply as possible, and I beg the patience and forgiveness of more advanced readers who may take exception with one or two nit-picking details.
1) Shannon's Information Theorem:
Shannon's Theorem states that the maximum amount of information that can be transmitted by a particle equals one-half the velocity of the particle. Fast-moving particles have more momentum, travel in straighter lines, introduce less delay, and are less likely to be perturbed by outside influences.
2) Heisenberg's Uncertainty Principle: The Uncertainty Principle tells us that the more precisely the position of a particle is known, the less information that particle can store. This is really just an extension of Shannon's Theorem. To precisely know the position of a particle, its velocity must be zero and therefore it cannot store any information.
3) Einstein's General Theory of Relativity: The General Theory of Relativity is summarized by the well-known equation, E = mc^2. Because E (energy) and m (mass) are on opposite sides of the equation, this means that as the energy of a particle increases, its mass decreases. Since the energy of a particle is proportional to the factorial of its velocity, this puts an upper bound on how fast a particle can travel. As velocity approaches the speed of light, energy approaches infinity, mass approaches zero, and there literally is nothing of the particle left to push against. This also explains why objects moving at the speed of light don't age: a massless particle cannot interact with the universe, and thus cannot be influenced by any object or force that would cause it to degrade.
4) G�del's Incompleteness Theorem: The Incompleteness Theorem states that any logically consistent system of inference cannot be complete. Conversely, any complete system of logical inference cannot be consistent. This is a profound result. It literally proves that science, which by definition must be consistent and logical, cannot completely explain nature. Any scientific theory that hopes to explain all of nature by necessity must be logically inconsistent. This, in turn, is irrefutable proof that a complete understanding of the laws of nature cannot be attained though science, but only through faith.
Now, we can use what we've learned to explain and affirm the rules of Modern amplifier design:
* Prefer high voltages over low voltages
High voltage electrons move faster and therefore carry more information. This is why tubes sound better than transistors, and high-voltage transmitting triodes sound best of all.
* Prefer vacuum to solid state
A particle traveling in a vacuum is free of influence from external forces. It moves at the speed of light in a perfectly straight line, and therefore has infinite information carrying capacity.
* Prefer straight conductors to curved ones
Forcing electrons to go around curves causes them to lose information. Avoid twisting signal wires whenever possible.
* Prefer thin conductors
Thin wires (or foil) have low mass and therefore exert less gravitational force on the electrons moving through them. This reduces "gravitational drag" that slows down the electrons, causing them to shed information.
* Prefer light-colored or uninsulated wire
Light colored insulation has fewer additives and therefore lower mass, reducing gravitational distortion. Light colored insulation also has a lower index of informational absorption, helping to preserve signal integrity. For these reasons, whenever possible, the best wire insulation is no insulation.
* Prefer widely-spaced conductors
When conductors are routed in close proximity to one another, the attractive force of electrons moving at different velocities disrupts the smooth flow of the signal.
* Prefer triodes to pentodes
The extra grid in a pentode slows down the electrons and forces them to travel in curved lines, introducing distortion. This is why triodes are more linear than pentodes.
* Prefer a stiff chassis
Vibration in a conductor causes the electrons inside to rattle around and bang into one another and the molecules of the conductor, disrupting the orderly signal flow and converting low-level information into heat.
* Prefer low-value capacitors
For a given amount of charge (e.g., information carrying capacity) a smaller capacitor has a higher terminal voltage than a larger capacitor. Higher voltage translates to higher velocity, and therefore higher information retrieval.
* Prefer low DC resistance
Resistance slows electrons down and perturbs them from straight-line motion, severely restricting fine information carrying capacity.
Well, I think this about covers what I have to say for now. I hope this explanation and set of design guidelines proves useful to anyone interested in making the transition into the exciting new world of Modern amp design!
If this posting proves useful to DIY enthusiasts, I may follow up in the future with more information on this profoundly important subject.
-Henry

Edits: 05/04/12 05/04/12 05/06/12

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A primer on Modern Physics as it relates to tube amp design

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