Many moviegoers want to have a personal home theater, but not everyone can afford such a whim. Everyone leaves this situation in their own way: someone will get simple Chinese speakers, someone will adapt Soviet-made acoustics for bass, but the most advanced ones, who have knowledge in radio engineering, will construct a subwoofer low-frequency channel on their own. Moreover, it is quite simple.
General information
Consider what a regular subwoofer is. In fact, this is a simple active low- pass filter , the input of which signals from the linear output (right and left channels), an amplifier and a woofer are fed. In this article, we will consider the most complex element of the device - a circuit that allows you to independently assemble a low-pass filter for the subwoofer. Such devices reproduce frequencies not exceeding 40 Hertz. They are used in conjunction with small satellite speakers. Subwoofers are active and passive. The latter are a low-frequency head connected to a common amplifier. Such devices are ineffective and unpopular. A completely different matter is the first option. In such devices, an electronic low-pass active filter for the subwoofer and a separate power amplifier separate the bass from the signal that is fed to the main speakers directly in the place of the supplied path, where filtering this signal will introduce the lowest level of nonlinear distortion compared to filtering the output power amplifier. Adding a separate amplifier to the subwoofer channel will significantly increase the dynamic range, as well as free up the medium and high frequencies amplifier from additional load.
Filter for subwoofer: circuits
The reader is invited to consider three options for schemes of such a device. In the first scheme, the simplest filter for a subwoofer, made in the form of an adder on a single transistor, is proposed. Serious sound quality with such a device cannot be achieved, but, due to its simplicity, it is perfect for beginner hams. But the filter for the subwoofer, presented in the following two versions, with great success has established itself as a device with excellent characteristics. Such devices are installed directly after the linear output of the source and input of the power amplifier. Filter for subwoofer characterized by low noise, low power consumption, as well as a wide range of supply voltage.
Conclusion
Summing up, let’s say that adding an active type subwoofer significantly reduces the lower limit of reproduced frequencies, improves the clarity of sound at medium frequencies and provides a fairly high volume level without distortion. Elimination of the low frequencies from the spectrum of the main reproduced signal arriving at the satellites allows them to sound cleaner and louder. This is because the cone of the low-frequency head does not oscillate with large amplitude, trying to reproduce bass and thereby introducing distortion into the signal.