Project Hub /Audio Displays & Interactive Media/Analog Audio & Amplifier Circuits/Audio Equalizer / Tone Control Circuit with Bass, Treble and MID Frequency Control using Op-Amp

Audio Equalizer / Tone Control Circuit with Bass, Treble and MID Frequency Control using Op-Amp

Advanced

ANALOG / DISCRETE

₹500 – ₹1,500

3 – 6 Hours

Partial Kit

Audio Equalizer / Tone Control Circuit with Bass, Treble and MID Frequency Control using Op-Amp

Design and build an active audio tone control and equalizer circuit powered by a TL072 operational amplifier featuring bass, treble, and mid-frequency controls.

Originally published on CircuitDigest

View original tutorial

Parts You'll Need

This project is sourced from another site, not written by us — this list is our best match of their components against what we stock, not a verified bill of materials. Always check the original blog (linked above) for the actual parts list before buying.

MB102 Adjustable Breadboard Power Supply Module (3.3V & 5V) for Arduino & Raspberry Pi Rs. 139.00
10pcs - 220 ohm 1/4 W Resistor Set Rs. 39.00
400 Points Mini Solderless Prototype PCB Breadboard High Quality Rs. 89.00
Jumper Wire 10 Pin Male To Male 20cm Rs. 45.00
Jumper Wire 10 Pin Male To Female 20cm Rs. 45.00

Selected: Rs. 0.00

This list includes a generic resistor set as a placeholder — it is not matched to the exact value or part number this circuit needs. The correct one is specified on the original source page linked above; check it before buying.

We don't carry yet: Potentiometer / Trimpot
Speaker / Audio Amplifier
Capacitors
Custom PCB / PCB Fab

Browse all components

How It Works

This active audio tone control and equalizer circuit relies on a TL072 operational amplifier (or JRC4558) configured to manipulate specific frequency bands of an incoming audio signal. Powered by a 12V power supply, the circuit utilizes a custom PCB layout designed in Eagle PCB Design Software. The operational amplifier acts as the active gain element, providing signal buffering and amplification while minimizing degradation. Surrounding the op-amp is an intricate network of resistors and capacitors—such as the 100uF, 10uF, 2.2uF, 0.1uF, and various nanofarad and picofarad capacitors—which form frequency-selective filter networks. These filter networks divide the audio spectrum into adjustable bands. Potentiometers, specifically two 100k potentiometers and one 470k potentiometer, serve as the user interface for the bass, treble, and mid-frequency controls. By adjusting the resistance values via these potentiometers, the user alters the feedback loop and frequency response of the op-amp circuit, allowing for precise boost or cut of low, middle, and high frequencies before the audio signal is passed onward to an amplifier system or speaker setup.

Why Build This

Design and optimize active filter networks for multi-band frequency response shaping in undergraduate analog signal processing coursework.

Integrate operational amplifiers into custom preamplifier stages for home theater systems or custom audio mixers.

Gain hands-on PCB layout experience using Eagle PCB Design Software for low-noise analog audio hardware.

Real-World Application

Audio amplifier systems, home theater setups, custom audio mixers, and musical instrument preamplifiers.

Skills You'll Learn

Active filter design

operational amplifier circuit configuration

frequency response shaping

tone control implementation

analog audio preamplifier design

PCB layout with Eagle

Safety Precautions

No specific precautions noted for this build — always follow general electronics safety practices.

Technology Tags

OP-AMP

TL072

ACTIVE FILTER

AUDIO EQUALIZER

TONE CONTROL

PCB DESIGN

ANALOG ELECTRONICS

Frequently Asked Questions

Can I substitute the TL072 operational amplifier with another op-amp?

Yes, the project notes state that a JRC4558 can be used as an alternative, as both are dual operational amplifiers suited for audio applications.

What is the purpose of the 12V power supply in this circuit?

The 12V power supply provides the necessary DC operating voltage for the TL072 operational amplifier to actively process, buffer, and amplify the audio signals.

Why are there different types of capacitors (such as uF, nF, and pF) used in the circuit?

Electrolytic capacitors (like 100uF and 10uF) are typically used for power supply decoupling and bulk filtering, while film and ceramic capacitors (like nanofarad and picofarad values) are deployed in the frequency-selective filter networks to target specific audio bands.

Gallery

This page is part of Kitkraft's Project Hub — a curated collection of electronics & robotics projects gathered from the maker community to help students and hobbyists discover and learn to build. Kitkraft does not claim authorship of the original project, and makes no representation as to the accuracy, completeness or safety of third-party source material. The summary and "How It Works" explanation above are AI-generated, rewritten with reference to the original tutorial — not a reproduction of it. Full credit and a direct link to the original source are provided above. If you're the original creator and have a concern about how your work is represented here, please contact us and we'll address it promptly.

Kitkraft Project Hub — curated from the maker community, credited at the source.

PRJ-00238