The Brimar circuit. The upper input terminal goes through a 0.047 u f cap to the grid, pin 2, of a 12 eh X 7. The lower input terminal is grounded. The grid goes through a 470 k ohm resistor to ground. The cathode, pin 3, goes through the parallel combination of a 2.7 k ohm and 50 u f cap to ground. The plate, pin 1, goes through a 100 k ohm res to plus 250 volts. The plate also goes through a 200 p f cap to the clockwise end of the treble pot, 500 k ohm linear. The CCW end goes through another 200 p f cap to the plate, pin 6 of the other triode in the 12 eh X 7. Pin 6 goes through another 100 k ohm res to plus 250 volts. This circuit is highly symmetrical. The plate of the first triode, pin 1, also goes through the left hand 100 k ohm res then through the left hand 0.0022 u f cap to ground. The plate, pin 6, goes through the right hand 100 k ohm then through the right hand 0.0022 u f cap to ground. The CW end of the bass pot, 1 meg, linear, goes to the junction of the left hand 100 k ohm res and 0.0022 u f cap. The CCW end of the bass pot goes to the junction of the right hand 100 k ohm res and 0.0022 u f cap. The wiper of the bass pot goes through a 0.01 u f cap then a 1 meg ohm res to the wiper of the treble pot. The junction of the 0.01 u f cap and 1 meg ohm res goes through a 2 meg res to ground. The wiper of the treble pot also goes to the grid, pin 7 of the 12 eh X 7. The cathode, pin 8, goes through the parallel combination of a 2.7 k ohm res and a 50 u f cap to ground. The plate, pin 6 goes through a 0.1 u f cap to the upper output terminal. The lower output terminal is grounded. End verbal description.
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