Low frequencies - a concept that includes the spectrum of sound heard by the human ear. On average, it is in the range from 20 Hz to 20 kHz. Audiograms that determine the ability to feel the lower threshold of each frequency have their own individual characteristics, so we can talk about the average hearing. Typically, frequencies below 40 hertz and above 16 kilohertz affect the color of the sound rather than feel on their own.
The range of sound reproducing and transmitting equipment is different, therefore the requirements for it differ. For example, a regular phone reproduces sounds from 200 Hz to 3 kHz, and this is enough to clearly disassemble everything said into the handset on 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" - broadcast loudspeakers. Nevertheless, with regard to the frequency range, a world standard has been adopted according to which Hi-Fi class equipment should have a frequency band of 20 to 20,000 Hz and wider.
Low frequency amplifiers are used universally as part of electronic circuits of various industrial and household appliances, as a separate type of radio equipment. They are in computers, televisions, radios, CD-players, walkie-talkies, mobile phones, intercoms and in many other subjects 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 an understanding of a loud person with a low understanding that he can enjoy, you can see absolutely monstrous four-digit numbers marked “PMPO” on the package with a receiver or amplifier. These letters should, in principle, indicate the peak load that the audio equipment may give out briefly. Actual power is the value that provides the undistorted shape of the sine wave at a frequency of 1000 Hz, applied to the input of the amplifier.
- The coefficient of non-linear distortion is a value that shows how low frequencies in their shape at the output stage differ from the input signal. This is perhaps the most important parameter, talking about how well made and tuned low-frequency amplifier.
- Dynamic range. This characteristic is very important for high-quality amplification equipment, it gives an idea of how straightforward the gain curve is. In other words, with a wide enough dynamic range, all low frequencies will be undistorted, regardless of their level. Both very quiet and very loud sound will be reproduced reliably. This quality is characteristic of 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 frequency scale throughout the entire operating range.
These parameters determine the quality with which low frequencies are reproduced by classical amplification equipment. In some modern samples of household musical equipment, frequency characteristics are deliberately distorted to create fashionable effects, such as amplification of bass components or ultra-high frequencies, which adversely affects hearing and brain function.