Furthermore, nickel based transformers have cores that cannot abide unbalanced DC current, as they saturate easily in the presence of unidirectional DC current. But by using a using a coupling capacitor in a para-feed arrangement we ensure that there is no net DC current. In other words, the para-feed arrangement allows for the use of a higher quality output transformer. I am sure that either the Jensen transformer company or SESCOM might have an excellent nickel transformer on the shelf
   Plate loading, with either para-feed or directly arranged, might allow for only getting away with only one triode per channel, i.e. one tube envelope, as the output transformer's stepping down of the output voltage would be cancelled by the plate's gain. Feedback could even be wrapped around the amplifier to a small degree. Two such amplifier layouts are shown below.

  On the other hand, cathode loading, with either para-feed or directly attached, will necessitate at least two stages and thus at least two tube envelopes, and thus half the available battery time. But this penalty might be worth the benefits of a lower output impedance and lower distortion. Two such amplifier layouts are shown below.

  Note that the para-feed arrangement shown above does not use a choke, but instead a solid-state current source. The current source might prove a better choice than a choke, as high quality chokes are also hard to find. Most chokes were designed for use in power supplies and do not work well across the audio band. A simple test of a choke is to place two in series with each other. Then ground one end of the string and attach the other end to a function generator. Finally, observe the waveform fidelity at the midpoint between the two chokes on an oscilloscope.

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