Active electronic three-way speaker

Half of the dual op amp 1/21C1 is connected in the form of a follower. It has
the characteristics of high input impedance and low output impedance, and serves as an input buffer here. The other half of the dual op amp, 1/21C1, forms a negative feedback tone control circuit. The potentiometer
RP1 is used to adjust the input signal amplitude and serves as a volume controller. Potentiometers RP2 and RP3 are used to adjust the high and low frequencies respectively.
The signal output by the tone control circuit is added to the three-way frequency dividing circuit. It consists of four groups of first-order RC networks, R10 and C9, which form
a high-pass filter. The crossover points are selected at lkF-Iz and 4kHz, and the attenuation rate is 6dB/. ct D adopts a first-order RC frequency division network, which has the advantages of
simple circuit, few components, and good phase characteristics. The attenuation at the frequency division point is only 3d B, the depression valley is shallow, and the
amplitude curve of the entire frequency division circuit is relatively flat. The post-frequency high, medium and low frequency signals are added to the monolithic power integrated circuit IC2, and are
amplified by the three internal power amplifiers respectively, and then drive the three speakers to play loudly.