LA3600 Audio Equalizer Circuit

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In this tutorial, we are going to make an “Audio Equalizer Circuit”. An audio equalizer in sound recording and reproduction is the process of adjusting the volume of different frequency bands within an audio signal. Most hi-fi equipment uses relatively simple filters to make bass and treble adjustments. It is a lite extension, that let you easily adjust audio settings. Here is a simple audio equalizer circuit constructed by using the famous 5-band graphic equalizer IC LA3600.

This is a monolithic linear IC from Sanyo and comes in DIP (Dual Inline Package) with 16 pins. It has an on-chip one operational amplifier and a 5-band graphic equalizer for one channel. The equalizer can be formed by using a simple capacitor and variable resistor units. We can build 10 bands equalizer by connecting two LA3600, and we can control different frequency bands.

Hardware Required

S.no	Component	Value	Qty
1.	IC	LA3600	1
2.	Resistor	220Ω,10KΩ,3.3KΩ	1,1,1
3.	Capacitor	47uf,3.3uf,22uf,100pf,0.039uf,0.0039uf,0.012uf, 0.0012uf,0.068uf,0.0068uf,0.22uf,0.022uf	Each One
4.	Variable Resistor	100KΩ	5
5.	Connecting Wires		–
6.	Battery	12V	1

Circuit Diagram

Working Explanation

The audio equalizer circuit we construct takes single audio input. This input signal is divided by variable resistors and given to separate base inputs in the equalizer IC (you can split stereo audio or can equalize by two LA3600 ICs). Here all these base inputs are amplified together by an internal op-amp, then the output audio signal comes out from pin 13.

This circuit needs a 12 Volt power supply to operate and LA3600 IC can have up to 20-volt Vcc supply. Now as we can see in the circuit, five different bands are separated by fixed capacitors and variable resistors. Here each band output can be varied by using variable resistors (VR). An equalizer can be used to correct or modify a speaker system frequency response, instead of designing the speaker itself to receive the desired response. You can use a slide potentiometer, instead of a variable resistor (VR) to make the circuit more professional.