Differential
phase splitter arrangements
     Like the split-load phase splitter, four good arrangements and two bad arrangements are possible when cascading into a series push-pull output stage, but of the four good arrangements, two are conceptually redundant, as they simply reverse the input polarities. We have already covered one of the bad arrangements and below is the second.

     In the circuit below, keeping the same output connection to the phase splitter, but reversing the phase splitter's connection to the output tubes converts the output stage back to a cathode follower based one, as the bottom tube now sees a fixed signal and the top tube sees any movement at its cathode mirrored at its grid.

     The above amplifier is a bad design because the top tube is functioning as a cathode follower while the bottom tube is functioning as a grounded cathode amplifier. Notice that a positive going voltage pulse applied to the output would force the top triode's cathode more positive than its grid, greatly reducing its conduction, while the bottom triode would only see a slightly greater cathode-to-plate voltage and it would only slightly increase in conduction as a result. Once again, the only load impedance that would equalize the current delivery into the load would be zero ohms, as any greater load impedance will unbalance the output stage's current conduction into the load impedance. Reversing the phase splitter's connection to the output stage inverts the phase at the output, but does not improve the situation, as the top and bottom tubes still function in a dissimilar fashion.

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