Figure 12.1. On the left is an AC generator. The top terminal connects directly to the grid of one of the triodes in a 12 A X 7. The bottom terminal is grounded. The cathode goes through the parallel combination of a 1.5 k ohm resistor and a 50 u f capacitor. The plate goes through a 100 k ohm resistor to plus 250 volts. The plate also goes to one end of a second 100 k ohm resistor. We will come back and pick up the other end of this resistor later. The plate also goes through a 250 p f capacitor to the top end of a 250 k ohm pot which is labeled treble. The wiper of the treble pot goes to the top of the volume control pot, 1 meg ohm. The wiper of the volume control goes to the output and the bottom is grounded. The bottom of the treble pot goes to the top of the bass pot which is also a 250 k ohm. The junction of the treble and bass pots goes through a 0.1 u f capacitor to the hanging end of the second 100 k ohm resistor. The wiper of the bass pot connects to the top of the same pot making it a rheostat. The bottom of the bass pot connects to the wiper of the midrange pot which is given variously as 10 k ohms or 25 k ohms. The junction of the midrange wiper and bass bottom connects through a 0.047 u f capacitor to the junction of the 0.1 u f cap and the 100 k ohm resistor. The bottom of the midrange pot is grounded. The top connects to its wiper making it a rheostat. End of verbal description.
Go back.