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 average hearing. Usually, frequencies below 40 hertz and above 16 kilohertz affect the color of the sound rather than being felt by themselves.
The range of sound reproducing and transmitting equipment is different, so the requirements for it are also different. For example, a conventional telephone reproduces sounds with a frequency of 200 Hz to 3 kHz, and this is enough to clearly understand everything said into the receiver 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. However, with regard to the frequency range, a world standard has been adopted, according to which Hi-Fi equipment must have a frequency band of 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 computerstelevisions, radios, CD players, walkie-talkies, mobile phones, intercoms and many other items familiar to us.
The main characteristics of the amplifier are as follows:
- Power output. Nowadays, it is considered differently. For example, in order to give a little understanding person an idea of \u200b\u200bhigh volume that he can enjoy, you can see absolutely monstrous four-digit numbers marked “PMPO” on the package with a receiver or amplifier. These letters, in principle, should mean the peak load that audio equipment can output for a short time. Real power is the value that provides an undistorted 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 form at the output stage differ from the input signal. This is perhaps the most important parameter, indicating 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 straight the gain graph is. In other words, with a sufficiently wide dynamic range, all low frequencies will be undistorted, regardless of their level. Both very quiet and very loud sound will be reproduced faithfully. This quality is typical for tube amplifiers.
-frequency response. It has already been 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 the frequency scale throughout the operating range.
These parameters determine the quality with which low frequencies are reproduced by classical amplifying equipment. Some modern consumer music products deliberately distort the frequency response to create fashionable effects such as boosting bass or ultra-high frequencies, which are detrimental to hearing and brain function.
