In the circuit below, the same aims as the pervious circuit are achieved by different means. This time the equalization mechanism is found at the cathode end of the phase splitter. Once again the output works as a push-pull follower that does not invert the phase of the input signal nor does it provide any gain. The top device still sees the ground referenced signal and the bottom device sees the output referenced signal. The zener-capacitor combination is not needed, as the output DC couples to the bottom of the cathode resistor.

    The +1 Volt pulse also decreases the voltage across the cathode resistor, which in turn decreases the current through this resistor, which will also decrease the current flowing through the plate resistor, as both are in the same current path. Since the top of the plate resistor is fixed and cannot move the plate must move up one volt to make up for the one volt loss across the plate resistor. This means that the pulse applied to the output is relayed to the bottom output device via the coupling capacitor. Upon seeing the positive pulse, the bottom device will increase its conduction; thus bucking the positive going pulse. A negative going pulse provokes a negative pulse at the plate, which serves to decrease the bottom output device's conduction.
     When the output is terminated into an 8 ohm load, the output's connection to the bottom of the cathode resistor provides the equalizing drive for the bottom output device. To whatever degree the output voltage lags behind the top output device's input voltage is the degree that the output voltage will subtract from the raw drive voltage to the bottom output device. For example, if 21 volts of drive is needed to bring the output to +20 volts of output, then the top output device sees only +1 volt out of the +21 volts presented to its input. The bottom output device sees its raw -21 volts input signal being reduced by the +20 volts output voltage to only -1 volts.
     In the circuit below, the a differential amplifier provides voltage gain, while the output devices still function as unity gain followers. Both the bottom and top output devices receive the same magnitude drive voltages, which the zener-capacitor provides.

    Let's start with a grounded output (I always try both zero and infinity when I evaluate an amplifier, as I assume that if an amplifier can work into these two extremes, then it can work into any resistance.)  Since we have grounded the output, the circuit reduces to a split-load phase splitter feeding two grounded plate or drain or collector followers. The drive signal balance is ensured by the equal valued plate and cathode resistors. Like the previous circuit, the output impedance is equal to the reciprocal of the transconductance of the output device, when only one device conducts (Class-B); and half that value when both conduct (Class-A). This is shown by applying a +1 volt pulse to the output. The top device sees this pulse as a +1 volt negative pulse at its input, as the pulse forces the output device's grid or gate or base negative relative to its cathode or source or emitter. 

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