Low frequencies and their qualitative amplification

Low frequencies are a concept that includes the spectrum of the sound audible by the human ear. On average, it is in the range from 20 Hz to 20 kHz. Audiograms that determine the ability to sense the lower threshold of each frequency, have their own individual characteristics, so we can talk about the average hearing. Usually, frequencies below 40 hertz and above 16 kilohertz affect the coloration of the sound rather than feel on their own.

The range of the sound reproducing and transmitting equipment is different, so the requirements for it differ. For example, a normal phone reproduces sounds from 200 Hz to 3 kHz, and this is enough to clearly disassemble everything said in the handset at the other end of the wire or, in the case of using a mobile device, into a microphone. The same applies to the so-called "bells" - the broadcast loudspeakers. Nevertheless, with respect to the frequency range , the world standard has been adopted, according to which the Hi-Fi class equipment must have a frequency band from 20 to 20 000 Hz and wider.

Low-frequency amplifiers are used everywhere as part of electronic circuits of various industrial and household appliances, as a separate type of radio engineering. They are in computers, televisions, radios, CD-players, walkie-talkies, mobile phones, intercoms and in many other things that are usual for us.

The main characteristics of the amplifier are the following:

- Output power. Nowadays it is considered differently. For example, in order to create a perception of a low understanding person about the high volume, which he can enjoy, on the package with a receiver or amplifier you can see absolutely monstrous four-digit numbers marked "PMPO". These letters in principle should mean a peak load, which can be briefly given out by the audio equipment. Real power is the value that provides an undistorted shape of the sinusoid at a frequency of 1000 Hz applied to the input of the amplifier.

- The coefficient of nonlinear distortion is a quantity that shows how low frequencies in their form on the output stage differ from the input signal. This is perhaps the most important parameter, which says how well the low-frequency amplifier is made and tuned.

- Dynamic range. This characteristic is very important for high-quality amplification equipment, it gives an idea of how straightforward the amplification schedule is. In other words, for a sufficiently wide dynamic range, all low frequencies will be undistorted, regardless of their level. And very quiet, and very loud sound will be reproduced reliably. This quality is characteristic of tube amplifiers.

Frequency response. About it already mentioned in the article, you can add only such a feature of it as uniformity. Ideally, it is a straight line parallel to the abscissa with a frequency scale throughout the working range.

These parameters determine the quality with which low frequencies are reproduced by classical amplifying equipment. In some modern samples of household musical equipment, frequency characteristics are deliberately distorted to create fashion effects, such as amplification of bass components or ultrahigh frequencies, which adversely affects hearing and brain work.