An audio crossover serves as an electrical filter designed to channel the appropriate audio signals to specific speakers or drivers within audio systems. This is essential because the majority of speaker drivers are unable to effectively reproduce the entire audio spectrum, experiencing distortion when handling both low and high frequencies. Consequently, most speaker systems incorporate multiple speaker drivers, each specializing in a distinct frequency range. The role of the crossover circuit is to divide the audio signal into various frequency bands, permitting these bands to be separately directed to the appropriate speakers.
Outline
- Active Audio Crossover Circuit Principle:
- Active Audio Crossover Circuit Diagram:
- Active Audio Crossover Circuit Design:
- LM833 Dual Audio Operational Amplifier:
- Dual Power Supply Circuit Design:
- How to Operate Active Audio Crossover Circuit?
- Active Audio Crossover Circuit Applications:
Active Audio Crossover Circuit Principle:
Audio crossover circuits can be categorized into two main types: active and passive. Passive audio crossover circuits are straightforward and rely on passive components to divide the audio signal into different frequency bands. However, they tend to waste a significant amount of energy and may introduce distortion.
On the other hand, active crossover circuits employ active components to split a complex audio signal into distinct frequency bands, overcoming the limitations associated with passive crossovers. In audio systems, active crossover circuits are typically recommended due to their advantages.
Active crossover circuits work by separating the input audio signal into two bands: a low-frequency band and a high-frequency band. These two frequency bands are then individually amplified using two power amplifier stages. One stage is dedicated to amplifying the low-frequency band, while the other is focused on the high-frequency band. This approach allows for more precise control and improved audio quality in sound systems.
Active Audio Crossover Circuit Diagram:
Active Crossover Circuit Diagram
Circuit Components:
- LM833Dual High-Speed Operational Amplifier – 2
- 24k Resistors (1/4 watt) – 7
- 6.2k Resistors (1/4 watt) – 2
- 6.8nF capacitors – 3
- Audio jack
- Connecting wires
- Breadboard
Active Audio Crossover Circuit Design:
The LM833 Dual audio operational amplifier from National Semiconductors is the major component in the above crossover circuit. The crossover circuit requires four operational amplifiers, thus we’ll need two lm833 ICs to build it. There are two portions to this active crossover circuit: a high pass filter section and a low pass filter section. At pin1, the operational amplifier U2:A forms a first order low pass butterworth filter, providing low band frequencies. High band frequencies are provided via the audio operating amplifier U1:B at pin7.
The frequency of the given active crossover circuit is calculated using the formula
Fc = 1/(2πRC)
For the given components the frequency of the crossover circuit is 1 KHz.
LM833 Dual Audio Operational Amplifier:
This IC is a high-performance dual operational amplifier for data signal and audio applications. This IC may be powered from a single or dual supply voltage over a wide range of voltages. This IC’s operational voltage ranges from +/- 5V to +/- 18V DC. It has a large gain bandwidth. Large output voltage swing with no dead band crossover distortions, minimal harmonic distortion, and low input offset voltage are some of the other advantages. The most common application for these ICs is in hi-fi systems.
LM833 IC
Features:
- Noise voltage is low: 4.5nV/
- Slew rate is high: 7V/uS
- Excellent Gain and Phase margins
- Low harmonic distortion: 0.0002%
- High open loop AC gain: 800 at 20 KHz
Dual Power Supply Circuit Design:
Dual Power Supply Circuit Diagram
Circuit Components:
- 12-0-12V, 500mA center tapped transformer
- Diode bridge – 1A
- 680uF Electrolytic capacitors – 2
- 0.01uF capacitors – 2
How to Operate Active Audio Crossover Circuit?
- Initially give the connections as per the circuit diagram
- While giving the connections, make sure that there is common connection between AC and DC supplies
- Provide +15V and -15V supply to the active crossover circuit from Dual power supply circuit.
- Apply the audio input to the circuit with the help of audio jack.
- Now you can observe low band frequencies at the pin1 of U2:A and high frequencies at the pin7 of U1:B
- Switch off the supply.
Active Audio Crossover Circuit Applications:
- This circuit is used in HiFi audio systems to separate the frequency bands from audio signal.
- Used to drive different types of loudspeakers.
Limitations of the Circuit:
This circuit is theoretical and may require some changes to implement it in practical.
