One example of loudness control circuit

 Figure 1-89 is an example loudness control circuit . The potentiometer taps at 30% of the total resistance from "ground". When the sliding arm
is rotated to the tap position, the measured midrange is attenuated by 30dB, the bass at 100Hz is attenuated by about 23dB (ie, a relative increase of 7dB), and the treble at
10kHz is attenuated by about 27dB (ie, a relative increase of 3%).