Graphic equalizers are super important in audio systems because they let people change the volume of different sound frequencies helping to create a sound that fits their personal preferences.
Designing a 5-Band Audio Equalizer Circuit divides the sound into five different sections, allowing users to adjust each section on its own.
The LA3600 integrated circuit is specifically designed for equalizers making it easy to use, reliable and high performing.
This article explores the details of how to design and use a 5-band graphic equalizer circuit that works with the LA3600 IC.
Circuit Working:
Note: C9 capacitor is 390pF mistakenly written 390μF
Parts List:
| Component Type | Specification | Quantity |
|---|---|---|
| Resistors | 180Ω, 10k, 4.7k, 1/4 watt | 1 each |
| Potentiometers | 100k | 5 |
| Capacitors | Ceramic 0.039μF, 0.012μF, 0.0039μF, 0.0012μF, 390pF, 0.68μF, 0.22μF, 0.068μF, 0.022μF, 0.0068μF, 100pF | 1 each |
| Electrolytic 3.3μF 25V | 2 | |
| Electrolytic 47μF 25V, 22μF 25V | 1 each | |
| Semiconductors | IC LA3600 | 1 |
The circuit diagram for Designing a 5-Band Audio Equalizer Circuit with IC LA3600 is shown above.
The main part of this design is the LA3600 integrated circuit, which is super important.
It works with a bunch of capacitors and resistors that help define the different frequency bands.
When the audio signal enters the circuit, it gets changed by the equalizer before it goes to the output.
The LA3600 IC is made to handle audio signals all in one chip giving users the chance to control five different frequency bands.
This means you can boost or lower specific frequencies as needed.
The IC acts like a set of band pass filters with each filter matching one of the frequency bands.
When the audio signal comes into the circuit it first goes through capacitor C15 and resistor R8.
These components help with AC coupling and make sure the impedance is just right.
Inside the IC the signal splits into five paths each set up with its own resistor capacitor RC combo that sets the center frequency for the band pass filters.
These paths match the five frequency bands, which are determined by the external parts:
- Band 1 is set by C1 and R1
- Band 2 is controlled by C3 and R2
- Band 3 is defined by C5 and R3
- Band 4 is set by C7 and R4 and
- Band 5 is determined by C9 and R5.
You can adjust the gain for each band by changing the resistance values, which lets you fine tune the audio.
After processing the signals from each band are combined and sent through capacitor C11.
In the output stage resistors and capacitors are used to finalize the signal.
Formulas with Calculations:
Below mentioned are the formulas with calculation for Designing a 5-Band Audio Equalizer Circuit with IC LA3600:
The center frequency (ƒc) for each band pass filter is determined by the RC network and is given by:
ƒc = 1 / (2πRC)
where,
- ƒc is the center frequency in Hz
- R is the resistance in ohms
- C is the capacitance in farads
Using the values from the circuit diagram:
- Band 1: R = 100k, C = 0.039µF ƒc = 1 / (2π × 100,000 × 0.039 × 10^-6) ƒc = 41 Hz
- Band 2: R = 100k, C = 0.012µF ƒc = 1 / (2π × 100,000 × 0.012 × 10^-6) ƒc = 132 Hz
- Band 3: R = 100k, C = 0.0039µF ƒc = 1 / (2π × 100,000 × 0.0039 × 10^-6) ƒc = 408 Hz
- Band 4: R = 100k, C = 0.0012µF ƒc = 1 / (2π × 100,000 × 0.0012 × 10^-6) ƒc = 1.33 kHz
- Band 5: R = 100k, C = 390pF = 1 / (2π × 100,000 × 3.9 × 10^-5) ƒc = 4.085 kHz.
These calculations highlight the specific frequencies that each band filters or amplifies.
How to Build:
For Designing a 5-Band Audio Equalizer Circuit with IC LA3600 follow the below mentioned steps for connections
- Assemble all the components mentioned in the above circuit diagram.
- Connect pin 1 of IC1 LA3600 to capacitor C1.
- Connect pin 2 of IC1 LA3600 to pin 1.
- Connect capacitor C2 from pin 2 center leg of pot VR1.
- Connect pin 3 of IC1 LA3600 to capacitor C3.
- Connect pin 4 of IC1 LA3600 to pin 3.
- Connect capacitor C4 from pin 4 center leg of pot VR2.
- Connect pin 5 of IC1 LA3600 to capacitor C5.
- Connect pin 6 of IC1 LA3600 to pin 5.
- Connect capacitor C6 from pin 6 center leg of pot VR3.
- Connect pin 7 of IC1 LA3600 to capacitor C7.
- Connect pin 8 of IC1 LA3600 to pin 7.
- Connect capacitor C8 from pin 6 center leg of pot VR4.
- Connect pin 9 of IC1 LA3600 to capacitor C9.
- Connect pin 10 of IC1 LA3600 to pin 9.
- Connect capacitor C10 from pin 10 center leg of pot VR5
- Connect the third legs of pot from VR1 to VR5 to pin 11 of IC1 LA3600 to positive of capacitor C15, connect the negative of capacitor to resistor R8 viva Audio input.
- Connect the upper legs of of VR1 to VR5 to pot of pin 12 of IC1 LA3600.
- Connect capacitor C11 to pin 13 to pin 12 of IC1 LA3600.
- Connect pin 13 to positive of capacitor C12 and negative of capacitor to Audio output, connect a resistor R7 between capacitor C12 and audio output and GND.
- Connect pin 14 of IC1 LA3600 to resistor R6 and +VCC of +9V voltage supply, connect the positive of capacitor between pin 14 and resistor R6 and negative of capacitor to GND.
- Connect pin 15 of IC1 LA3600 positive of capacitor C13 and negative of capacitor to pin 16 of IC1 LA3600.
- Connect pin 16 of IC1 LA3600 to GND.
Conclusion:
Designing a 5-Band Audio Equalizer Circuit with IC LA3600 is a simple but powerful project for people who love audio.
It shows how RC circuits work in processing sound and helps you learn about designing equalizers.
By picking the right parts and adjusting the circuit, you can have great control over the sound frequencies in your audio system making your listening experience even better.