Here is the schematic of a 3 way active cross- over network circuit that finds a lot of application in audio amplifier systems. The heart of this circuit is National Semiconductor’s IC LF353 which is a dual JFET input operational amplifier with internally compensated input offset voltage. The IC LF353 has high bandwidth, low offset currents, and low input bias current due to the JFET based input stage.
The working of the circuit is very simple and straight forward. Two LF353 ICs are used here. The input audio signal is first buffered using the opamp IC2a and POT R7 can be used to adjust the gain of this buffer stage. The buffered audio input is then spited into three bands using the filters built around the opamps IC2b, IC1a and IC1b. IC2b handles the bass range, IC1a handles the mid range and IC1b handles the treble range.POT R22, R23 and R24 can be used to adjust the bass, midrange and treble respectively.
- Assembling the circuit on a good quality PCB improves the sound quality.
- The circuit cab be powered from a 12V DC supply.
- he ICs must be mounted on holders.
- The outputs OP1, OP2 and OP3 must be connected to the respective inputs of the multichannel power amplifier stage (not shown in circuit).