Two Way Active Crossover with Linear Phase Response

The circuit was designed for the purpose of creating an active crossover circuit for 2-way output while having a response that is linear in phase.

• Crossover – an external electronic signal processor that functions as a filter by limiting or blocking some range of frequencies sent to a speaker while allowing other frequencies to pass with little or no effect
• NE5532 – an internally compensated low noise dual operational amplifier with features such as full power bandwidth up to 140 KHz, input noise voltage of 8 nV, common mode rejection ratio, 9 V/us slew rate, high DC voltage gain, 32 V peak to peak voltage swing, wide supply voltage range from 3 V to 12 V, unity gain bandwidth at 10 MHz, and internal frequency compensation
• TL071 – a low noise JFET input operational amplifier with features such as common-mode input voltage range, high slew rate, operation without latch up, compensated internal frequency, high input impedance at the JFET input stage, low noise, low total harmonic distortion, protected from output short circuit, low input bias and offset currents, wide common-mode and differential voltage ranges, and low power consumption

The circuit represents an audio crossover specifically designed for use in hi-fi audio applications as they are considered as a class of electronic filters. A crossover can be considered active when they possess active components like the op-amp. They are being operated for the suited power amplifier input levels and the use of power amplifier for each output band is always required. In this circuit, two amplifiers are required which will be connected to the low frequencies or woofer, and high frequencies or tweeter.

To create this 2-way crossover circuit, standard capacitor values are selected while the values of the resistors are being calculated. The resistors may be placed in parallel or in series to achieve the proportionality of the cutoff frequency around 3 KHz by obtaining a theoretical value near the desired output. For the regulation of precise voltages, the 100K ohms trimmers TR1-2-3 are used but can be replaced by a potentiometer if desired.

The outputs shown in the figure represents the woofer in the low out speaker while the high out represents the tweeter that drives the power amplifier of the high speaker. To maximize damping control of the speaker voice coil, the speaker drivers are directly connected to the power amplifiers. Doing this reduces the consequences of dynamic changes in driver electrical characteristics while the transient response of the system is improved. The overdriving and intermodulation distortions are reduced due to the isolation of each driver from signals handled by drivers.

Crossover circuits are capable of covering the whole audio spectrum with low distortion and acceptable loudness that is why they are commonly used in loudspeaker drivers. They are used for the purpose of splitting the audio signal into separate frequency bands. Most 2-way crossovers are using high quality components for excellent sound reproduction. They are featured with one set of input and two sets of outputs consisting of high pass and low pass filters that directs signals of different frequency ranges to the loudspeakers optimally designed to handle those ranges. It makes the audio output play cleaner and louder due to the built-in filter that removes subsonic from the signal.

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