After a brief review of the history of the K2-W vacuum-tube op amp, an LTspice model is used to create its schematic in ...

Capacitor C1 is a Miller-effect capacitor. 2. The LTspice schematic of the K2-W op amp in a basic inverting configuration incorporates the symbol created for the K2-W model. The gain G is set to ‒1.

The added passive components at the NE570 inputs are chosen to allow R 3 to be adjusted for a 3 Vrms output from U 2A, the level at which its datasheet indicates that that op amp exhibits the lowest ...