While the extra gain is welcome, the worst PSRR figure of any of the circuits under consideration is not. A workaround was presented in the Tube CAD Journal's first issue, March 1999, which offered a way to eliminate the power supply noise at the output. This technique works at reducing the power supply noise at the output by introducing a portion of the power supply noise to the top triode's grid, where it will be amplified in anti-phase to the noise at the B+ connection. (Many do not realize that the top triode is capable of gain, which is not the case with FETs or transistors in place of the triode.)
    The triode's r_p makes the difference, as the bottom triode in effect becomes simply a large valued cathode resistor. Setting the ratio between capacitors, C2 and C1, to match the amplification plus one from the top triode will ensure that the noises cancel at the top triode's plate. For example, if the top triode realizes a gain of 3, then the ratio should be 2:1, as this would equal 3.

Cascode
     The cascode offers more potential gain than any of the previous circuits, with the final gain often far exceeding the mu of the triode.

     The cascode's gain roughly equals the triode's Gm against Ra:
      Gain =                        µR_a                   .     
                       (R_a + R_p) / (µ + 1)  +r_p

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