On the left is a generator which is labeled V1, AC 1. The lower end of the generator is grounded. The upper end goes to the input of the response control circuit R C C. The input of the R C C goes through a 24 k ohm resistor then a 220 p f capacitor to the C W end of the treble control, Which is represented by two resistors in series, R9 and R10. The 220 p f capacitor connects to the free end of r9. The value of R9 is given as PV minus R10. PV is the pot value. The value of R10 is given as R10. This makes the values of these two resistors variables which can be controlled by the program rather than being fixed. The free end of R10 goes to another 220 p f cap. The other end goes through a 24 k ohm res to the R C C output. The junction of R9 and R10 represents the wiper of the treble pot. It goes through a 220 k ohm resistor to the center of the R C C. The R C C input also goes through a 56 k ohm resistor to the outer end of R4. The series combination of R4 and R5 make up the bass pot. The value of R4 is given as PV minus R5 and the value of R5 is given as R5. This makes the values of these two resistors variables which can be controlled by the program rather than being fixed. The outer end of R5 goes through another 56 k ohm res to the R C C output. There is a 0.0022 u f cap connected from outer end of R4 to the outer end of R5 which places it in parallel with the bass pot. The junction of R4 and R5 goes through a 1 meg ohm resistor to the center of the R C C.

There are lines of text on the schematic which are known as spice directives. They literally tell spice what to do with the schematic diagram. See Spice lessons for information on how to use these directives. As done previously they will be separated by the word next. Dot step param Pp 1 250 k 62.5k next dot param PV=250002 next dot param R5=PP next dot param R10=pp next dot ac dec 100 10 100k next dot op.

The center of the R C C goes to the control grid of a 6 A U 6. The cathode goes to ground through the parallel combination of a 1.2 k ohm resistor and a 150 u f capacitor. The screen grid of the 6 A U 6 goes through a 680 k ohm resistor to plus 250 volts. There is a 3.3 u f capacitor connected from the screen grid to the cathode, not ground. See text. The suppressor grid is connected to the cathode. Note, it appears to be common practice not to show suppressor grids on spice schematics. Their existence and connection is taken as a given. The plate goes through a 270 k ohm resistor to plus 250 volts. The plate also goes directly to the grid of a12 A U 7 triode. The plate of this triode goes directly to plus 250 volts. The cathode goes to ground through a 33 k ohm resistor. The cathode also goes through a 0.47 u f capacitor to a point labeled out. The point labeled out goes to the output side of the R C C. On the right side of the schematic is another generator labeled V2 250. The lower end is grounded and the upper end connects to plus 250 volts. End verbal description.
Go back.