An audio crossover is an electrical filter that sends the correct signal to the speakers or drivers in audio applications. Because most speaker drivers are incapable of covering the whole audio spectrum without distortion from low to high frequencies, most speaker systems employ a mix of numerous speaker drivers, each associated with a different frequency band. The audio signal is separated into multiple frequency bands by the crossover circuit, which can then be routed separately to the 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:
Active crossover circuits and passive crossover circuits are the two types of audio crossover circuits. Passive audio crossover circuits are very basic, and they use passive components to separate the frequency bands from the audio signal. However, a significant amount of energy is wasted, and distortion is introduced in this passive crossover circuit. Active crossover circuits use active components to separate a complex audio signal into separate frequency bands, and they are free of the limitations listed above.For audio systems, active crossover circuits are recommended. The input audio signal is separated into two bands by crossover circuits: a low frequency band and a high frequency band. Two power amplifier stages are used to amplify these two distinct frequency bands. The low frequency band is tuned in one stage, while the high frequency band is tuned in the other.
Active Audio 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.
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.
