Why do I need a subwoofer filter?

Many movie fans want to have a personal home theater, but not everyone can afford such a whim. Everyone comes out of this situation in their own way: someone will acquire simple Chinese speakers, someone will adapt the Soviet-made acoustics for bass, but the most advanced ones who know the knowledge in radio engineering will construct a subwoofer low-frequency channel themselves. Especially since it is quite simple.

General information

Consider what a normal subwoofer is. In fact, this is a simple active low- pass filter , which receives signals from the line output (right and left channels), amplifier and woofer. In this article, we'll look at the most complex element of the device - a circuit that allows you to build a low-pass filter for the subwoofer yourself. 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 inefficient and unpopular. Quite a different matter - the first option. In such devices, an electronic separation active low pass filter for the subwoofer and a separate power amplifier separate the bass from the signal that is sent to the main speakers directly at the point of the path being fed, where the filtering of this signal will introduce the lowest level of nonlinear distortion, as compared to filtering the output power amplifier. Adding a separate amplifier to the subwoofer channel will greatly increase the dynamic range, as well as free the mid and high frequency amplifier from the additional load.

Subwoofer filter: schemes

The reader is offered three variants of schemes for such a device for consideration. The first scheme proposes a simple filter for a subwoofer, made in the form of an adder on a single transistor. Serious sound quality with such a device will not be achieved, but, due to its simplicity, it is perfect for beginning amateur radio operators. But the filter for the subwoofer, presented in the following two versions, with great success proved to be a device with excellent characteristics. Such devices are installed directly after the line output of the source and the input of the power amplifier. Subwoofer filter Characterized by low noise, low power consumption, as well as a wide range of supply voltage.

Conclusion

Summarizing, let's say that adding an active subwoofer significantly reduces the lower limit of reproduced frequencies, increases the purity of sound at medium frequencies and provides a fairly high volume without distortion. Eliminating from the spectrum of the main reproduced signal, arriving at satellites, low frequencies allows them to sound cleaner and louder. This is because the cone of the low-frequency head does not oscillate with a large amplitude, trying to reproduce the bass and thereby distorting the signal.