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Or if beefy enough triodes are used, or if enough parallel triodes are used, a power amplifier for dynamic headphones or even speakers could be built.
As mentioned twice before, swapping the Split Load phase splitter's output connections to the top and bottom triodes transforms the output stage from being a voltage gain stage into a low output impedance, no-gain buffer. Of course, the DC coupling will no longer work as the Split Load phase splitter's cathode is at negative 290 volts and its plate is at negative 10 volts. Capacitor coupling takes care of the offset voltages and the DC feedback loop is removed, as it is no longer useable. (A diode is added to protect the phase splitter triode.)
What can be done to optimize this new configuration of the output stage?
If configured as a voltage gain stage, the Split Load phase splitter only needs an output voltage swing great enough to drive the output tubes to full output, i.e. only a few volts. But if the output stage has been reconfigured as a no-voltage-gain stage, all the desired output voltage swing must be present at the phase splitter's outputs.
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In other words, it is time to recalculate the cathode and plate resistor values. This is as simple as dividing the rail-to-rail voltage by 6 and then dividing that voltage by the desired idle current for the phase splitter. This approach ensures that each resistor and the triode all see the same voltage potential. So, in this example, the resistor values are set to 100k, the result of dividing 600 volts by 6 and then by dividing again by 0.001 amperes.
Maximum Output Swing
Just how much voltage swing is the Split Load phase splitter capable of given these new resistor values? The answer, when the Split Load phase splitter is locked into a fixed B+ voltage, would be almost one half the cathode-to-plate voltage in one direction and the voltage across the cathode (or plate) resistor in the other direction. Think of three rubber bands tied together with the ends tied to two fixed points with the knots representing the cathode and plate. In this circuit, the phase splitter does not work within a fixed voltage potential, but rather a dynamically expanding and contracting potential.
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