The Optimized Morgan Jones Earmax

In order for the WCF to optimally deliver current to the headphones the two triodes need to be operating in a balanced push-pull mode. This enables them to work in opposite phase, each drawing the same magnitude of current thus doubling the current delivery to the load. John Broskie, in a very early article from The Tube Cad Jounal, did some experiments with the WCF and determined that the best value for the plate resistor is R_p = 1/G_m, where G_m is the transconductance of the triode. Originally John asserted that this result is good for any value of the load resistor. After some prompting from Morgan Jones I actually calculated the value of R_p as a function of the load. You can read this article here. I mentioned my results to Broskie who then re-did his calculations to get the correct result.

Optimizing the push-pull action of the WCF leads to the values shown in this new schematic. I made a few other changes to get better operating points for the Optimized MJ amplifier.

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The Optimized Morgan Jones Amplifier