Tone circuit with high, mid and bass functions

Figure 4-7 is a tone control circuit designed and calculated using the relationship obtained from the above analysis , in which Ai is a buffer amplifier stage to reduce the burden on the front-stage output. The low-frequency turning frequency of this circuit is 30Hz, the high-frequency turning frequency is 1kHz, and the control range is ±20dBo. Using an operational amplifier can not only design a tone circuit with high and low bass control functions, but also design a tone control with high, medium and bass control functions. circuit.