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2003 |
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Copyright © 2003 John Broskie All Rights Reserved |
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hopelessly fuzzy wishful thinking that could never stand up to logical scrutiny, but which is politically correct, so exempt from debate and criticism.) From a basic electronic theory standpoint, both amplifier topologies are equally valid. From an electronic practice standpoint, the two topologies are too generic, too elemental, too basic, and ultimately, too similar to be evaluated without the rest of the amplifier fleshed out. Which is better positive voltages or negative voltages? Negative or positive power supplies? I don’t know, what does the whole circuit look like? One reader explained to me that the name “circlotron” revealed the true nature of the amplifier, as all the key parts defined one large circle of current flow. He was right, they do; however, all six topologies we have covered here should then share the name “circlotron,” as all of them equally complete circles of current flow: remove one part and the current ceases to flow. (But it is hard to imagine a Futterman amplifier being called a circlotron.) In other words, this path leads straight to distinctions based on no differences. (Of course, the marketing department may trump basic electronic theory and electronic practice by declaring that if the public is misinformed or misguided, great let’s make some money: sell them whatever they think is better and who cares if there is no difference?) |
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The circuit with the two tubes horizontally arranged, the circlotron (I would love it if we could lose the name “circlotron” and simply call it a “push-pull amplifier” or at most a “horizontal center-referenced push-pull amplifier”) offers the advantage of easier output tube biasing, as all the output tubes have their cathodes at same ground potential, allowing a shared negative bias power supply (and heater supply). Another advantage is that the two triodes within a 6AS7/6080 could more readily be wired in anti-phase to each other. In other words, while one is turning off, the other turns on, as was the standard practice not to long ago. But which is better...you know...metaphysically? No, I don’t know, nor does anyone else. Imagine two people arguing who was more powerful, Allah or God? Or which was nastier, the leopard or the panther? Or whether they should plant nutmeg or mace crops next year? In terms of performance, in the absence of any measurable differences, we would have to make nuanced, textured and subtle distinctions, as is in this one has more drive, or as in this one has less drive. (I am old enough to remember when “share” did not mean to burden someone else with our petty, private grievances, as in “Bob, I have something to share with you;” or when “nuanced” and “textured” and “subtle” might be overheard in a museum or a concert hall, but did not describe |
