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Driving the Accordion Amplifier
First of all, we do not need a phase splitter, which is a relief. Still, we have some work ahead of us. The easiest approach is to use an inter-stage transformer with two secondaries, one for each output tube. Two arrangements are possible. The first relies on the output tubes to provide voltage gain. Both secondaries are "grounded" at their respective output tube's cathode. Thus, although the top tube's cathode will swing with the output transformer's primary swing, its grid-to-cathode voltage swing will match that of the bottom tube. Given a 2A3 as an output tube, we will need to develop about 80 volts of peak-to-peak signal across the inter-stage transformer's secondaries to drive the 2A3 to full output. In other words, the driver tube must realize a gain equal to the 40 divided by the inter-stage transformer's winding ratio. (And yes, the 417A can certainly be used, as can the 6N1P.) For example, if the ratio is 1:2, then a gain of 20 is needed.
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