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October |
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Page 8 |
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Copyright © 2003 John Broskie All Rights Reserved |
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Think of it as the power supply leap frogging the triode. (Two power supplies will be needed in this example, but as each hold only half the power delivery as the one they replaced, no net increase or decrease in power supply strength results.) If the next circuit does not look familiar, it should, as it is the circlotron of high-end audio fame. (In your mind’s eye, bend and fold the bottom half of the circuit up and the familiar figure eight configuration will become apparent. If you need help, see the top of the next page.) |
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Generic one-tube-side-by-side-the-other push-pull class-AB amplifier with the signal reference shifted to the center of the output, a.k.a. the Balanced amplifier or the Circlotron amplifier |
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Note the similarity in drive signal strengths between circlotron and the last circuit, with one tube atop the other. The reference point falls at the midpoint of the output signal in both cases; the output triodes in both amplifiers function with same amount of signal degeneration at their cathodes (once again, much like cathode followers); and in both circuits the same voltage and current gain and output impedance are realized, as the triodes all share the same cathode-to-plate voltages and transconductance and see exactly the same IV dynamics. |
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