Direct coupled long tail pair. One side of the input is grounded. The other side goes through a 0.033 U F cap to the grid of triode 1. It is labeled one half 12 B H 7. The cathode goes through a 3.3 k ohm res to ground. The plate goes through 33 k ohm then a 180 k ohm 1 watt res to plus 400 volts. The junction of the 33 k and 180 k goes to the positive end of a 22 U F, 450 v, cap. The negative end is grounded. The plate of triode 1 goes directly to the grid of triode 2. The plate of triode 1 also goes through a 1 meg ohm res then a 0.22 U F cap to ground. The junction of the resistor and capacitor goes to the grid of triode 3. Triodes 2 and 3 are another 12 B H 7. The cathodes of triodes 2 and 3 are tied together and go to ground through a 15 k ohm resistor. The plate of triode 2 goes through a 33 k ohm 1 watt resistor to plus 400 volts. The plate of triode 3 goes through a 39 k ohm res to plus 400 volts. The plate of triode 2 goes through a 0.22 u f cap to output 1. Output 1 goes through a 100 k ohm res to ground. The plate of triode 3 goes through another 0.22 u f cap to output 2. Output 2 goes through another 100 k ohm res to ground. There is an extensive legend in the diagram. It reads as follows. V o = 17 volts, t h d 1 = 0.2 percent. T h d 2 = 0.5 percent. V o = 25 volts, t h d 1 = 0.34 percent. T h d 2 = 0.66 percent. V o = 50 volts, t h d 1 = 1.6 percent. T h d 2 = 2.1 percent. Gain = 29. f sub 2 = 206 k c. End verbal description.

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