Tube Amplification: Black Magic
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“Any sufficiently advanced technology is indistinguishable from magic”. So goes the third of Clarke’s Laws, the speculative-writing rules devised by sci-fi legend Arthur C. Clarke.
Clarke’s third law applies to the real world, too. For the vast majority of us, it describes to a tee the techno-gizmos that consume more and more of our lives. I have some friends who can partially explain the inner workings of an iPhone, but to me, that little black box might as well be a wizard’s wand.
Even older and simpler technologies fall outside of the collective ken. A world without cars would be unrecognizable, but most people can’t explain how a car works. I’m no exception. The best I can do is understand the gist of the internal combustion engine: you combine fuel with an oxidizer and blow it up. The resultant force drives pistons, which in turn drive a bunch of other devices. Somehow, at the end of this process, the car goes when you hit the gas. Magic!
Clarke’s third law also applies to a technology that’s even more central to my lifestyle: tube amplification.
Any metalhead with a passing interest in gear knows that tube amps are the key to the guitar tone that makes metal metal. Our heroes, from Hendrix to Motörhead to Maiden to Slayer, built their sound by piling Marshalls to the sky. “Metal” bands that use solid-state amps or combos are rudely told to leave the hall.
As with cars, I know the basics of tube amplification mechanics. This YouTube video covers most of them:
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Tube Amps Tutorial 2 – Structure
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A tube is a device that amplifies an electronic signal. When you play your guitar, a signal comes out of the pickup and goes through your cable and into the amp. It reaches a small ‘pre-amp’ tube (or several of such) that makes the signal bigger. From there, it goes to the larger power tubes, which expand the signal even more. This blown-up signal goes through an output transformer to the speaker cabinet. It makes the speaker cones wobble back and forth rapidly, moving air and creating sound. An array of volume and tone controls allow you to change the signal shape on the way.
But beyond this superficial knowledge, I’m at sea. And I doubt I’m alone. This FAQ page, written by tube engineer Eric Barbour, describes the way tubes themselves work. They’re like lightbulbs, apparently. A metal filament heats up in a vacuum and shoots electrons through some metal grids at another metal thingy. This process somehow amplifies the signal.
Though Barbour couches his explanation in friendly, everyday language, the description is nonetheless full of words and images that stop me in my tracks. “Cathode”. “Grid No. 3 Suppressor”. “Thoriated filament”. “Linearize”. Charts marked “Fig. X”. I feel painfully aware of my liberal-arts education while trying to parse this information. If someone put a gun to my head and demanded that I draw a circuit map roughly reflecting the workings of my own Mesa-Boogie Dual Rectifier, I wouldn’t have long to live.
The machines that make my beloved heavy metal possible remain a mystery to me. I suspect that most of my metal brethren are in the same boat. But is that such a bad thing? Metal is obsessed with the occult. That fixation goes beyond the colloquial meaning of “the occult” as supernatural lore. “Occult” means “hidden”, and metalheads are all about hidden knowledge. We love discovering obscure bands and categorizing them into absurd micro-styles. We love weird, arcane instrumental techniques. What is ‘sweep-tapping’? What does ‘Locrian’ mean? Only a few of us know for sure. We love production jobs that turn music into muck. (Well, some of us do.) And we love vocals that turn mere words into inarticulate weapons.
For me, underground metal is partially about danger. It’s especially about projecting what H.P. Lovecraft called the “oldest and strongest fear”: fear of the unknown. I like the feeling that I’m playing with forces that I don’t entirely understand. I like unnatural, inhuman sounds. So it’s fitting that the inner workings of metal’s key soundmaker remain occult to me. In an age of over-sharing and demystification, I’m glad we’ve still got some black magic at our disposal.
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