Low frequencies - a concept that includesspectrum of sound heard by the human ear. On average, it is in the range from 20 Hz to 20 kHz. Audiograms, which determine the ability to sense the lower threshold of each frequency, have their own individual characteristics, so we can speak about the average hearing. Usually, frequencies below 40 Hertz and above 16 kilohertz affect the color of the sound rather than being felt by themselves.
Range of reproducing and transmittingequipment is different, therefore, different requirements for it. For example, a regular phone reproduces sounds with a frequency from 200 Hz to 3 kHz, and this is enough to clearly disassemble everything said into the handset at the other end of the wire or, in the case of using a mobile device, into the microphone. The same applies to the so-called "bells" - broadcast loudspeakers. However, with respect to the frequency range, a world standard has been adopted, according to which Hi-Fi equipment should 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 subjects that are familiar to us.
The main characteristics of the amplifier are as follows:
- Output power.Nowadays it is considered differently. For example, in order to create a low-understanding person's ideas of 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 the peak load that the audio equipment can give out for a short time. The real power is the value that provides the undistorted shape of the sinusoid at a frequency of 1000 Hz, applied to the input of the amplifier.
- The coefficient of non-linear distortion - value,showing how low frequencies in their form at the output stage differ from the input signal. This is perhaps the most important parameter, indicating how well a low-frequency amplifier is made and tuned.
- Dynamic range.This characteristic is very important for high-quality amplifying equipment, it gives an idea of how straightforward the gain graph is. In other words, with a fairly wide dynamic range, all low frequencies will be undistorted, regardless of their level. Both very quiet and very loud sound will be played reliably. This quality is typical for tube amplifiers.
- Frequency response.About it was already mentioned in the article, you can add only such a feature as uniformity. Ideally, it is a straight line parallel to the abscissa with a scale of frequencies throughout the operating range.
These parameters determine the quality, withwhich reproduce the low frequencies of the classic amplifier equipment. In some modern models of household musical equipment, the frequency characteristics are deliberately distorted to create fashionable effects, such as amplification of bass components or ultra-high frequencies, which adversely affects the hearing and performance of the brain.
