Figure 5. This circuit has a similar appearance to figure 3 on the tone controls page. It is a similar circuit. Adding the tube amplifier did have some effects some expected and some not. Most notable is that the tone flat line is at minus 1.5 dB instead of minus 20 dB. That was expected. Both the boost and cut are not as large as they were for the purely passive circuit. The boost is more than the cut. Here the values at 10 Hz. Full cut minus 10, half cut minus 6, flat minus 1.5, half boost plus 5, and full boost plus 13.5 dB. The overall shape is the hourglass turned on its side. End verbal description.