Figure 2 A 12U7 Audio Amplifier Stage. On the left the audio input connects to one end of a 0.1 u f capacitor. The other end of the capacitor goes to the grid, pin 2, of the 12 U 7. The cathode, pin 3 goes directly to ground. The plate, pin 1, goes through a 15 k ohm resistor to plus twelve volts. The plate also connects to one end of another 0.1 u f capacitor. The other end is labeled audio output. End verbal description.