This amplifier a clever way to inexpensively make a high quality amplifier, as it used relatively cheap tubes and no output coupling capacitor nor output transformer (nor even a power transformer for the output stage). So why not build it today, tarted up a bit with high quality parts and power supply regulation? Simply, I do not think it will work as well as it once did. Not in its original form that is.
   Here is why.
   The original amplifier used eight 12B4s and put out 12 watts into a 16 ohm load. Today we use 4-8 ohm speakers. The peak (non-positive grid) output current a triode is capable of delivering into a load resistance is given by
     Ipk = B+ / (rp + Rload).
Since the rp of even four parallel 12B4s is much higher than any speaker impedance, the peak output current doesn't differ much between the 8 and 16 ohm load, but the peak output voltage is halved. In other words, the amplifier can only put out 5 watts into a 8 ohm load. Yes, 5 watts is more than any single 2A3 SE amplifier puts out and it is more than enough for a high efficiency midrange. (Now if the number of output tubes is doubled, the full 12 watts is possible. Since 12B4s are so cheap, doubling the number will not add much to the cost of the amplifier. Besides, as the amplifier runs in a lean Class-AB, each 12B4 dissipate less than 1 watt of heat at idle and should last forever.)
    If you wish to have only a Class-A OTL, then more or different output tubes will be needed. Here is an example of seductive thinking: commercially made OTL amplifiers use eight 6AS7s and they supposedly put out 60 watts of Class-A power; thus, one 6AS7 can put out 8 watts of Class-A power. Seductive, as only the truly false and misleading can be. First of all, these amplifiers only put out about 4 watts of Class-A power. So using the ratio method, one 6AS7 should put out half a watt of Class-A power; it still can't. The math falls apart because of the squared terms in the power calculations: double the output current or the output voltage and you quadruple the output wattage.
    Inversely, halving the output current or voltage, quarters the output wattage. This is the result of one variable's increase implying the increase of the other variable:
     P = ½I²R 
and
     P = V² / 2R  (RMS watts).

    The big problem that tube OTL amplifiers face is that the tubes are severely current limited. In contrast, solid-state amplifiers are voltage limited. Below is a grid that displays the peak current, voltage, and wattage relationships for an 8 ohm load:

   Since a Class-A, push-pull  amplifier can put out twice its idle current, a 4 watt amplifier will require an idle current of 500 mA. Each 6AS7 triode can safely be run with both a plate voltage of 110 volts and a idle current of 100 mA (11 watts of dissipation per triode). Thus, ten 6AS7  triodes would be needed per channel (five 6AS7 envelopes). This number does not change with push-pull topology; either the Circlotron or the totem pole arrangement requires ten 6AS7 triodes. The output impedance depends on the feedback topology, but in the absence of feedback, 9 ohms is my guess.
   If these tubes are allowed to go into Class-AB operation, 16 watts will be delivered into an 8 ohm load. Why so few watts? The high idle current subtracts from the potential watts, as the onset of positive grid voltage defines a limit for the grid's excursions and the greater the idle current, the closer we come to that limit. If you are willing to live with grid current conduction, the potential wattage radically increases, as does the likelihood of tube failure and increased distortion. The following screen capture displays the composite plate curves for 5 parallel 6AS7s triodes. Even with this high idle current, some non-linearity is readily seen.

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