The tone control is a type of equalization used to make specific pitches or “frequencies” in an audio signal softer or louder. A tone control circuit is an electronic circuit that consists of a network of filters that modify the signal before it is fed to speakers, headphones, or recording devices by way of an amplifier. It allows listeners to adjust the sound to their liking and compensate for recording deficiencies, hearing impairments, room acoustics, or shortcomings with playback equipment.
For example, older people with hearing problems may want to increase the loudness of high pitch sounds they have difficulty hearing. It can be used to adjust an audio signal during recording. For instance, if the acoustics of the recording site causes it to absorb some frequencies more than others, tone control can be used to amplify or “boost” the frequencies the room dampens. Here we design a simple Baxendale tone control circuit by using op-amp IC741 and other easily available components.
Hardware Components
| S.no | Component | Value | Qty |
|---|---|---|---|
| 1. | Transistor | BC107 | 2 |
| 2. | Resistor | 47KΩ,3.3KΩ,330KΩ,220KΩ,100KΩ,2.2KΩ,10KΩ | 2,2,1,1,2,1,1 |
| 3. | Variable Resistor | 100KΩ,500KΩ | 1,1 |
| 4. | Capacitor | 2.2uF,6800pF,1500pF,10pF,10uF,22uF | 2,2,1,1,1,1,1 |
| 5. | Connecting Wires | – | – |
| 6. | Battery | 30V | 1 |
Circuit Diagram
Working Explanation
The op-amp IC741 can be very effectively used for processing audio frequencies and customizing them as per one’s own choice. If we prefer more bass in music, it may achieve by just adjusting the bass control shaft. Whereas those who appreciate extra treble with music may do the same through another similar control reserved for the purpose. Here the first stage is the Baxendale tone control circuit, which is connected to the input of the operational amplifier (IC 741). This amplifier is connected with negative feedback. Now audio input is directly applied to the tone control circuit, and then the controlled audio signal is amplified by the operational amplifier. Here the output is taken from pin 6 of the op-amp.
Applications
Used in many sound systems: radios, portable music players, boom boxes, public address systems, and musical instrument amplifiers.
