Equivalent circuit for treble boost

Adjusted to point D, the treble is boosted
    (1) When only considering the effect of Vi on Vb and not considering the effect of Vo on Vb, the equivalent circuit is as shown in Figure 1-82 (a).
It shows that if the capacitive reactance to the high audio signal C4 is small, Vb will be large, and if the capacitive reactance to the low audio signal C4 is large, Vb will be small;
relatively, the high audio signal will be improved.
    (2) Only consider the relationship between Vo and Vb If the effect of Vi on Vh is not considered, the equivalent circuit is shown in Figure 1-82 (b)
. At this time, since the resistance of Hu Yao is large and the resistance of R12 is small, the negative feedback effect can be ignored. When its comprehensive characteristics are adjusted
to point D, the high- frequency signal is enhanced, as shown in the curve in Figure 1-82 (c).