Diachronic classification of the acoustic intrоductiоn

DIACHRONIC CLASSIFICATION OF THE ACOUSTIC

INTRОDUCTIОN……………………………………………………………4
CHAPTER I. GENERAL INFORMATION ABOUT ACOUSTIC SYSTEMS…………………………………………………………………...14
1.1. Classification of loudspeakers……………………………………………9
1.2. The principle of operation of acoustic systems…………………………12
1.3. Structural diagram and main elements of acoustic systems…………….14
CHAPTER II. MAINTENANCE AND REPAIR OF SPEAKER SYSTEMS……………………………………………………………………24
2.1 Setting up and adjusting speakers………………………………………..20
2.2. Diagnosis and testing of loudspeakers…………………………………..24
CОNCLUSIОN………………………………………………………………26
LIST ОF USED LITERАTURE…………………………………………….27

Intrоductiоn

Acoustic system - a device designed to effectively emit sound in the air, including one or more sound emitters in acoustic design. The nature of the sound is determined not only by the parameters of the installed radiators, but also by their relative position, cabinet design, built-in passive filters and many other elements of acoustic systems. Acoustic system - a device for reproducing sound.
The acoustic system can be single-band (one broadband emitter, for example, a dynamic head) and multi-band (two or more heads, each of which creates sound pressure in its own frequency band). radio sound column
The number of bands into which the speaker's frequency range is divided.
For different sound frequencies, speakers of different design are used, which are capable of reproducing sound in a certain frequency range with high quality, but they reproduce sounds with a different frequency with distortion.
On sale you can find 2.5-way speakers. They install one high-frequency speaker (for high-frequency range) and two low-frequency speakers at once, one reproduces only Low Frequencies-range, and the second - two at once: Mid Frequencies and Low Frequencies¹.
The acoustic system consists of an acoustic design (for example, a bass-reflex type, a closed type, an open type, with a passive radiator). The disadvantages of such acoustics are low sensitivity, not very deep bass, the advantages are simplicity of design and good transient characteristics, which guarantee a low level of distortion and accurate sound reproduction.
A variety of bass-reflex speakers are speakers with a passive radiator, or "passive radiator". By design, they resemble speakers with a phase inverter, but instead of it, a passive radiator is installed in an additional hole. It is part of a low-frequency loudspeaker without a coil and a magnetic system and performs the same role as a phase inverter. The passive radiator is selected so that its resonant frequency is equal to the lower operating frequency of the loudspeaker. This improves the reproduction of low frequencies. This design is often used in subwoofers. One of the advantages of a passive radiator over speakers with a conventional phase inverter is the absence of airflow noise in the resonator tube.
Open-type acoustic systems are very rare, in which the case is a thick panel in which the speakers are installed. Such loudspeakers provide acoustic radiation of the dipole type, that is, sound vibrations from the speaker propagate both from the front and from the rear².
Due to the fact that there is practically no cabinet in such speakers, all the negative vibrations that occur during resonance in speakers with a "normal" cabinet are minimized.
Bass reproduction is weakened in open-type speakers, so manufacturers have to install very large woofers. Most modern loudspeakers use a bass-reflex design.

1. GENERAL INFORMATION ABOUT ACOUSTIC SYSTEMS

The purpose of acoustic systems is to reproduce sound and melodies, for example, in a car. This made it possible to listen to music, radio or, what has become fashionable now, audio books while traveling.
The audio system is built from two main components: the head unit (radio) and the sound reproduction device - acoustic systems (AC, or speakers). Today, dynamic loudspeakers (“speakers”, or loudspeaker heads) are used as the main component of the AU, which are distinguished by reliability, simple design and acceptable technical characteristics.
Specifications of the speakers, which should be paid the most attention when buying.
- Power (RMS)
Many firms in the technical characteristics of their products indicate the so-called "musical" power. During measurements, a short-term (less than 2 s) signal with a frequency below 250 Hz is applied to the acoustic system. If there are no perceptible distortions, then the speaker is considered to have passed the test. This does not take into account the nonlinear distortion of the signal. Naturally, this method allows you to specify very high values ​​of "power", often 10-100 times higher than the maximum sinusoidal. This parameter very poorly characterizes the real quality of sound reproduction. Therefore, the main power value that you should pay attention to when buying a speaker system is RMS power. It is measured by applying a sinusoidal signal with a frequency of 1000 Hz until a certain level of non-linear distortion is reached. For example, in the data sheet of the product it is written: 25 W (RMS). This means that the speaker system, when a 25 W signal is applied to it, can work for a long time without mechanical damage to the speakers.
Nonlinear distortions are distortions that manifest themselves in the appearance in the frequency spectrum of the output signal of components of noise and overtones that are absent in the input signal.
How much power is needed for high-quality sound? This is determined by the parameters of the room in which the installation of this equipment is planned, the characteristics of the speaker itself, as well as the needs of the listener himself. For an average apartment, power from 20 to 50 watts is enough. - Frequency range
This is the band of frequencies reproduced by the acoustic system. In speakers with a subwoofer, the entire frequency range is divided into two parts - low frequencies are reproduced by the subwoofer, and medium and high frequencies are reproduced by satellites.
The ideal frequency range would be approximately 20 to 20,000 Hz.
The evenness of the frequency response is also affected by the number of bands for the reproduction of acoustic systems. The ideal choice is 3-way loudspeakers with active separation of the signal into HF (high frequency), MF (middle frequency) and LF (low frequency) ranges using so-called crossovers, followed by 3 different signals to 3 speakers of the speaker system. This makes it possible to carry out independent amplification in different bands of the spectrum, which in turn allows you to provide the optimal mode of operation for each speaker in the speaker system. Most often, three-way speakers can be recognized by the presence of 3 different speakers in the speaker cabinet.
For games and movies, two-way systems are also suitable. It is worth saying that, in principle, such systems are also suitable for music, if you do not impose super-demands on the quality of playback or you do not have enough money for an elite audio system.
Crossover - a device for dividing an audio signal into several components. - Signal to noise ratio
The signal-to-noise ratio is a dimensionless quantity, for a discrete signal it is equal to the ratio of the signal energy per bit or symbol to the noise spectral density. Usually expressed in decibels. The larger the value, the less noticeable extraneous noise is during audio playback.
1.1 Classification of loudspeakers
With the current pace of development of radio broadcasting, television, sound recording, sound, warning, etc. and the transition to fundamentally new digital technologies for working with sound, the need for a variety of acoustic systems and the requirements for their quality are increasing all the time. Depending on the purpose, they have significant differences in parameters and are distinguished by a wide variety of designs and designs. Volumes of production of acoustic systems and loudspeakers for various applications reach tens of millions of pieces per year, hundreds of companies are engaged in their production. New classes of acoustic systems designed for Multi-Media, Home-Theatre, etc. appear, computer methods for their design and measurement are introduced, new materials and technologies are used, etc. All types of acoustic systems presented on the modern market,
· speaker systems for home use, which in turn can be divided into systems: mass; high quality - HI-FI and HIGH-END categories; acoustic systems for home audio-video complexes - Home-Theatre; for modern computer systems -Multi-Media, etc.;
· acoustic systems for sound systems and sound amplification, incl. for conference systems and speech translation systems (these, in particular, include sound speakers);
· concert and theater acoustic systems, incl. powerful block portal systems, sound systems for the hall and stage, etc.;
· studio acoustic systems - acoustic monitors (units) designed to control sound quality in various video-recording studios, radio-television studios, etc.;
· automobile speaker systems, as well as - speaker systems for scoring other modes of transport (airplanes, trains, etc.);
· speaker systems for intercoms, public address systems, subscriber systems and for other service applications.

1.2 The principle of operation of acoustic systems

In any home theater, the final quality of sound reproduction is determined by the speakers. The best recordings, encoded with the latest technology, read in a high-end Blu-ray player, processed and amplified by a high-quality AV receiver or AV processor with amplifiers, can be irreparably ruined by bad speakers.
Sound Basics
Any source creates sound due to oscillatory movements, like an ordinary bell (guitar string, human vocal cords, etc.). When the metal of the bell vibrates, the layers of air molecules adjacent to it also begin to vibrate, and these oscillatory movements propagate in the air in waves, eventually reaching the eardrum in the human ear. The vibration of the tympanic membrane is interpreted by the brain as sound and, depending on the specifics of the oscillatory movements, is identified by the source of the sound wave³.
The perceived sound seems different due to the frequency of the sound wave - faster or slower vibrations of air molecules and the eardrum, and the amplitude of the wave - stronger / weaker vibrations that displace the elastic membrane more / less. A change in the amplitude of a sound wave is perceived by a person as a change in the volume of an audible sound.
The recording microphone works on the principle of the human eardrum - an elastic membrane perceives sound vibrational waves, which are then encoded as electrical signals on a magnetic tape or digital disk. A DVD or Blu Ray home theater player reads the recorded signal from the disc, the decoder of the AV receiver or AV processor decodes it and puts it into different channels, then the signals are amplified and transmitted as electrical impulses to the loudspeakers (speakers) of the acoustic systems, which convert the electrical signals into the oscillatory movements of the diffuser, which actually creates sound waves perceived by a person.
Sound speakers have recently become known as speaker systems. In other words, these are not only boxes with ordinary speakers. Modern models of acoustics are a real engineering miracle that is capable of reproducing sound of maximum accuracy. 
The equipment is widely used in concert events, cinemas, theatrical performances, club parties, etc.
The design of the speakers at first glance really looks like an ordinary box in which ordinary speakers are built. However, the internal structure of such equipment is much more complicated.
In most of their model variants, speakers have the following design: 
head, which is responsible for the range of sound variations;
body, mostly plastic or wood;
filter chains and adjustments, which are a prerequisite for obtaining the purest sound;
in addition, speakers are equipped with auxiliary electronic equipment: for example, a device that prevents system overload, or a volume indicator;
cables and terminals for communication with other devices;
amplifiers are additionally introduced into active-type speakers. 
The principle of operation of the AU is a physical phenomenon, namely, the conversion of electrical impulses into signals of a directly sound type. Speaking in the language of physics, then in the acoustic system the already mentioned electrodynamic head interacting simultaneously with the magnetic field and the coil. After the entire process of interaction, the emitter "throws" sound waves into space.
Types of acoustic systems 
It should be said about the constructive types of acoustic equipment. We said above that in speakers the head of the loudspeaker refers to the main element, another terminology is the head of the electrodynamic type.
If the speaker is equipped with one such head, then such equipment is called single-band. More than one unit of heads in the composition of the speakers classify them as a multi-band system. In multi-band acoustics, each of the heads must operate in its specific frequency range. As a result, it gives the effect of a deeper, clearer and higher quality sound.
Single-way systems are not widely used. The engineers failed to create such a head that is capable of simultaneously reproducing sound of different frequencies with the same quality.
Today, the maximum number of strips (heads) in one equipment can be four. 
The next type of AS hierarchy is also closely related to the design features of the equipment. Modern models can be purchased in two versions: with or without a built-in amplifier. The first model variants refer to the active type of acoustics, the second to the passive type.
Today, in most cases, active systems are used, which provide for a design with an embedded amplifier. The advantages of active speakers are much less problematic connection and operation. There is no need to buy additional equipment (amplifier). 
To connect the active system to other equipment, it is sufficient to use a standard interconnect type cable. With passive speakers, this simplicity will not work - they require a special cable.
We said that active speakers are used more and more today. But many musicians still prefer passive acoustics. If you understand this in more detail and compare both types, you can understand such conservatism. 
Speakers can be located quite high, so in case of problems with the amplifier it is quite difficult to quickly and efficiently intervene in its operation. Typically, each of the speakers is equipped with an amplifier, and therefore a musician needs two power supplies. And this is additional financial expenses. 
There are several other types of speakers that have not won much prestige among professionals. For example, systems of electrostatic type. Instead of speakers, the development uses a special film that emits acoustic waves. The sound is quite good, but such speakers do not work well with low-frequency sound. 
How modern speakers are connected 
Most speakers are connected to amplifiers with two-pole cables. Do not forget that we are talking about passive type speakers, which require a special cable, in this case with two poles⁴. 
Active type acoustics, as mentioned above, is connected to various equipment using simple interconnect cables. An RCA connector is enough to connect to a computer. Professional speakers of the active type are connected to the equipment using XLR connectors.
It is worth first of all to pay attention to the marking of the terminals. Often, the positive terminals are indicated by the corresponding sign - "+". If such a marking is not met, then by default the positive terminal is considered red.
The opposite side of the wire must be equipped with a plug. It may also be that the plug is simply missing, in which case the wires should be connected in a bare form. The ends of the wire in this case are connected to special clamp-type terminals. Many model variants can be connected to amplifiers using Speakon connectors. 
Do not forget that for home acoustics you may not need any wires and cables. Modern models in many of their variants are wireless. 
Connecting speakers to amplifiers at a great distance (especially important for large concert venues) is carried out only with the help of a special transformer, which is able to increase the output voltage of the audio signal. Without such equipment (even with high quality cables) power will be wasted. 

1.3 Structural diagram and main elements of acoustic systems

A classic sound system, as shown in Figure 1, contains: a sound recording and playback module; synthesizer module; interface module; mixer module; acoustic system.
The first four modules are usually installed on the sound card. Moreover, there are sound cards without a synthesizer module or a digital sound recording / playback module. Each of the modules can be made either in the form of a separate microcircuit, or be part of a multifunctional microcircuit. Thus, the Chipset of a sound system can contain both several and one microcircuit. The designs of the PC sound system are undergoing significant changes; there are motherboards with a Chipset installed on them for sound processing. However, the purpose and functions of the modules of a modern sound system (regardless of its design) do not change. When considering the functional modules of a sound card, it is customary to use the terms "PC sound system" or "sound card"
The acoustic system consists of the following main elements:
emitters (low-, medium-, high-frequency HG), the number of which in each of the bands depends on the type of speakers;
The emitters used in the vast majority of speakers are electrodynamic loudspeaker heads GG. In a number of speakers, electrostatic, isodynamic, etc. are also used. In domestic terminology, such speakers are commonly called "AS with non-traditional radiators."
In remote speakers, as a rule, a multi-band construction principle is used, i.e. the entire reproducible frequency range is divided into several frequency subranges, each of which is reproduced by its own HG, which, depending on this, is called low-, medium- or high-frequency. The highest category speakers usually use three or four frequency subbands; mass speakers often use a one- or two-way construction principle. This is due to the fact that the use of a single broadband loudspeaker does not make it possible to ensure the uniformity of the frequency response of acoustic power in the full frequency range and reduce the level of intermodulation distortion. Requirements for GG operating in different frequency ranges differ significantly.
The speaker enclosure is the main structural element that forms its electro-acoustic characteristics in the low-frequency region by regulating the load on the rear surface of the diffuser and using or suppressing the radiation from this surface. It has a significant effect on the electro-acoustic parameters of the speakers both in the low-frequency region (such as the amplitude-frequency characteristic - AFC, phase-frequency - PFC, directivity characteristic - XH, non-linear distortion coefficient), and in the region of medium and high frequencies due to vibrations of the walls of the case on its internal volume, as well as due to the influence of the shape of the case on the nature of the diffraction effects.
The most common enclosure types in today's loudspeakers are the closed enclosure, the bass reflex enclosure, and the passive radiator enclosure. There are also other types of less commonly used cases: “folded horn”, “maze”, transmission lines, etc⁵.
The closed housing serves to suppress the radiation from the rear surface of the GG diffuser.
The phase-inverted housing is distinguished by the presence of a hole or a hole with a tube in it, which increases the sound pressure level in a certain low-frequency region due to the radiation from the rear surface of the diffuser.
A case is quite widely used, in which, instead of a hole or a tube, a passive radiator is used, which is a loudspeaker with a movable system without a magnetic circuit and a voice coil. A passive radiator also makes it possible to increase the level of sound pressure through the use of rear radiation, especially in the resonance frequency region of the system, formed due to the mass of the moving system of the radiator, the flexibility of its suspension and the air contained in the housing.
AU electronic devices include, first of all, electrical separation filters. Almost all modern speakers are multiband for the reasons mentioned above, so the distribution of the energy of the audio signal between the HG is the main task of the filters. The development of AS design techniques forced changes in the functions of filters and their design methods. Separation filters now simultaneously perform the tasks of filtering and correction. In the vast majority of modern manufactured speakers, so-called "passive" filters are used, which are switched on after the power amplifier. However, in a number of AC models, “active” crossover filters are also used. In this case, each frequency channel uses its own power amplifier, connected after the filters. Compared to passive filters, active filters have a number of advantages:
The terminals in high-end speakers are usually of the spring type with a special design.
A simple circuit that allows you to automate the inclusion of speakers for a personal computer (PC) electronically. A study of PCs with different sound cards from the antediluvian SB-1868 to modern ones (Creative Labs SB 0092) found that the sound card output (speaker connector) has some peculiarities. When the PC is turned on, the oscilloscope connected to this connector registers bursts of pulses.
2. MAINTENANCE AND REPAIR OF SPEAKER SYSTEMS
2.1 Setting up and adjusting speakers
A rectangular room is best for installing and setting up a speaker system. The system should be placed along the long wall of the room. To get a smooth and clear sound, you need to properly position the furniture and textiles in the room. Then you get a clear and elastic, high-quality sound. Sometimes it is enough to move one or another large object in the room just a few centimeters to dramatically change the sound quality. In the room where the acoustic system is set up, the floor must be covered with a soft carpet⁶.
In order for the sound localization to be clear, the speakers are placed at the same level as the listener's ears. The speaker system is set up so that the speaker setup points and the listener position are at the top of an equilateral triangle. Adjustment and tuning of sound localization is carried out by changing the angle of the direction of the speakers to the listener.
If possible, the speaker system should be located away from the corners, and the distance to the back wall should be different from the distance to the side walls, otherwise the effect of mutual cancellation of sound waves may result. There should be no objects, bedside tables, racks, etc. between the listener and the speakers.
A rectangular room is best for installing and setting up a speaker system. The system should be placed along the long wall of the room. To get a smooth and clear sound, you need to properly position the furniture and textiles in the room. Then you get a clear and elastic, high-quality sound. Sometimes it is enough to move one or another large object in the room just a few centimeters to dramatically change the sound quality. In the room where the acoustic system is set up, the floor must be covered with a soft carpet.
In order for the sound localization to be clear, the speakers are placed at the same level as the listener's ears. The speaker system is set up so that the speaker setup points and the listener position are at the top of an equilateral triangle. Adjustment and tuning of sound localization is carried out by changing the angle of the direction of the speakers to the listener.
If possible, the speaker system should be located away from the corners, and the distance to the back wall should be different from the distance to the side walls, otherwise the effect of mutual cancellation of sound waves may result. There should be no objects, bedside tables, racks, etc. between the listener and the speakers.
To begin with, let's remember that computer speaker systems are active, i.e. contain not only speakers, but also at least a two-channel amplifier with a power supply.
If there is no sound, you must first check the speakers themselves.
To do this, turn on their power and remove their plug from the sound card connector.
This can be done "on the go", nothing terrible will happen.
The volume control must be set to the maximum position.
CHECKING THE HEALTH OF SPEAKERS
Then you need to touch the end of the plug with your finger. If a soft background (low-frequency hum) is heard from the speakers, then the amplifier and speakers are working. In this case, the malfunction may be in the computer - in the sound card or its driver.
We omit the most banal case (the AC plug is inserted into the wrong connector).
But just in case, we recall that most often there are three connectors on a built-in or external sound card: microphone input, line input and speaker output.
Most often, the AC output is green.
Near the entrances, if you look closely, you can see the corresponding icons.
Bios photo with sound off
Maybe the sound is simply disabled in the Windows settings. Check them out. Just in case, go to the BIOS Set Up and see if the built-in sound card is disabled?
If everything is in order with the settings and the driver (while other speakers sound normal), then the speakers themselves need to be repaired. In this case, there will be no background and no other sounds.
CHECKING AND REPAIRING THE SPEAKER POWER SUPPLY
The power supply is built into one of the speakers. It usually contains a step-down transformer , a diode bridge and a filter capacitor.
When turned on, it should produce a small constant voltage. Recall that you can measure voltage and other parameters with a digital multimeter .
The magnitude of this voltage can be indirectly estimated from the operating voltage of the filter capacitors, which is indicated on its case.
The operating voltage of the power supply should be slightly less than the operating voltage of the capacitor. Usually it lies in the range of 9 - 18 V.
If the power supply is good, you should check for an open speaker coil with a digital multimeter.
The resistance of the speaker coils most often lies in the range of 4 - 8 ohms.
Its size is usually worn by the speaker housing.
If it is less, then there are short-circuited turns.
In this case, the loudspeaker will no longer work normally.
If the coil resistance is too high, the coil is broken. These speakers need to be replaced.
There is no point in repairing them.
CHECKING THE VOLUME CONTROL
If the speakers and power supply are OK, the problem may be in the volume control. You should, touching the speaker plug with your finger (when it is on), carefully move and turn the knob.
If, at the same time, intermittent rustles and a background are heard from the speakers, this indicates that the cause is a poor contact of the regulator.
In some cases, this grief can be helped by replacing the regulator.
If there is nothing to replace the regulator (variable resistor), then short-circuit its central and one of the extreme conclusions (upper in the diagram) , and change the volume using the volume control in the computer.
Thus, we will bypass the regulator and apply the full signal to the input of the amplifier.
One of the extreme terminals of the regulator is connected to the common wire of the amplifier circuit, the other is the input.
You need to short the input pin with the average.
If you mistakenly short the middle terminal of the regulator to the one on the common wire, there will be no sound in the speakers at all. But the amplifier will not burn out, do not worry!
The regulator is usually dual, it simultaneously adjusts the volume level in both channels at once. It is necessary to short each regulator separately.
In conclusion, we say that there may be more complex malfunctions. The amplifier chip may fail. It usually doesn't work to replace it. On the other hand, many computer speakers are so cheap that it makes no sense to bother with their repair.
If there is no voltage, you can suspect an open transformer winding.
You can “ring out” the transformer windings with the same tester. The resistance of the primary winding can be in the range from several tens to several hundred ohms. The more powerful the transformer (the larger its dimensions), the lower the resistance of its primary (and secondary too) winding.
The resistance of the secondary winding should be in the range from a few ohms to several tens of ohms.
If even one of the windings breaks, the transformer must be replaced. You should check the fuse (if any) and, if it is defective, replace it with a similar one.
Sometimes, when the voltage in the electrical network rises, the diode bridge or capacitor fails.
The diode bridge can be checked with a multimeter. A failed capacitor can be identified by swelling or cracking of its top cover. Defective parts must be replaced with similar ones.
Repairing the speaker power supply is not difficult due to its simplicity.
No need to put any kind of "bugs" (jumpers from the wire). Such a jumper, as a rule, has a larger section than the required one and will not be able to limit the current. This is fraught with an increase in the number of malfunctions and light, sound and pyrotechnic effects.

2.2 Diagnosis and testing of loudspeakers

Purpose of testing. The main purpose of testing the quality of acoustic systems is to determine the quality of the product according to the developed criteria on an absolute scale and in comparison with competitors. The success of acoustic systems as a successful product depends on a combination of many factors. Of these, the following, the most important for the user, can be distinguished: appearance, ergonomics, functionality and sound quality. The cost of the product is also an important factor when buying, but the most relevant price / quality indicator for its price category, in comparison with its closest competitors.
To compare columns with each other, as well as a clearer idea of ​​each product, it is advisable to investigate and compare products according to all the main features that determine the integral quality assessment.
Direct comparison with competing products is most useful, with the reference path as the absolute benchmark.
Objective tests. For greater accuracy, the analysis uses objective parameters - the main existing indicators that can be obtained as a result of measurements. These are the unevenness of the amplitude-frequency characteristic (AFC), on-axis and off-axis indicators, harmonic distortion in the operating frequency band, analysis of the 2nd and 3rd harmonics separately, screenshots of the spectrum at control frequencies.
AFC characterizes the operating frequency range of the device and the uneven transmission of timbre. Off-axis frequency response characterize the focus on the high frequencies. For active acoustics, the frequency response in the extreme positions of the tone controls shows the corresponding capabilities of the product. The harmonic level indicates the audible component of the harmonic distortion. This very useful parameter is not recorded by most measuring laboratories. When measuring the harmonic coefficient (2+3 harmonics), we use our own unique technique of gradually increasing non-multiple logarithmic sinusoids of a fixed frequency with a musical interval.
Measurements are made by a specially designed hardware and software system. When measuring frequency response, a logarithmically increasing sinusoidal signal of a long duration is used, with auto-tuning of the phase during analysis. This makes it possible to obtain measurements that are closer to reality, since an energetically similar test signal is closer to a musical one. It also excludes artificial docking of the theoretically obtained low-frequency range according to approximate simulation results.
A great difficulty is the transmission of auditory sensations from listening in the form of verbal descriptions. In the literature and the media, you can find several approaches to describing the sound of audio equipment. The most common approach: the use of emotional epithets from areas that have nothing to do with the generally accepted musical terminology, and also not related to the technical description of physical processes. So, for example, you can meet the expressions "delicious bass", "adult sound", "degree of intimate involvement". Another approach may consist in setting and subsequent manipulations with numerical estimates for such items as “stage depth”, “image stability”. Such phrases do not have any clear definition or standardized scientifically based basis, and their interpretation is supposed to be at the personal discretion of the listener. Here, one cannot do without the involvement of an esoteric anti-scientific subjective emotional (audiophile) rating system, individual for each such listener. At the same time, the value of such an assessment is extremely doubtful, even when trying to identify some kind of pattern. No useful conclusions can be drawn about the price / quality ratio or the successful design of the speakers.
The basis of the assessment system used in our methodology is:
1. Scientific base, with an idea of ​​the ongoing physical processes (spectral analysis, time analysis, etc.). An acoustic system (column) is a complex non-linear electro-acoustic device with a set of inherent properties. Therefore, when evaluating, physical terms from the field of Physics, section Acoustics, are applicable.
2. Musical approach. The reproduced signal is music, so it can be considered by musical criteria. This makes it possible to characterize quality without inventing and standardizing new terminology.

CОNCLUSIОN

The advantage is an integrated approach. For example, the phrase: “a good acoustic system attack allows you to more accurately convey the touches of a performance,” combines scientific and technical and musical lexicons. While the phrase "the intimate-mystical sound of the speakers excited and covered with a wave of emotions" does not carry any useful information, except for the increased emotional excitability of the listener.
This approach also has disadvantages. For example, some minimum preparedness of the reader is assumed. On the other hand, test results imply an orientation towards an interested person who is ready to learn something new if it can really help in his tasks of choice or broadening his horizons.
Regardless of the fact that outwardly acoustic systems look quite reliable devices, they also tend to break down. The cause of breakdowns can be not only a factory defect, but also improper use. Acoustics, like any other technique, does not like to be operated at maximum power. If the volume knob is turned to the maximum, the power supply will produce the most power. In acoustic systems, the built-in PSU is designed to be used in the rated power mode, so when it is increased to the maximum, it will heat up, and the elements of its circuit will work with a heavy load. In addition, the PSU can fail during power surges. Released power supplies may be repairable, which should be carried out in specialized service centers.
The amplifier microcircuit may fail, then the repair of the acoustic systems will consist in replacing it. At the same time, it is worth deciding whether such a replacement will be economically justified. If the speakers are inexpensive, it's easier and cheaper to replace them. Loudspeakers - speakers are less prone to breakdowns. The speaker, with impaired sound, can be replaced. The reason that the loudspeaker wheezes may be its long operation at maximum power, if the speaker breaks, or when it is accidentally pierced with a sharp object. If the volume or frequency control is broken in the speaker system, the user, by adjusting the desired parameters, will hear crackling from the speakers. In this case, the repair will consist in replacing new regulators (variable resistors) or soldering them. The lion's share of defects is associated with incorrect connection, breakage of connecting cables, problems with the sound card or incorrect settings in the PC. As a rule, the cable breaks due to careless connection, as well as disconnection of the plug to the sound source, so all connections must be with good contact and as reliable as possible. When using an acoustic system, it is necessary to place it away from heating devices, during a thunderstorm, unplug it from the outlet. This will help you avoid an early repair of the speaker systems. Microphones and headphones are also subject to breakage if they are used incorrectly, carelessly, carelessly. A malfunction may occur due to a violation of the contacts or their breakage. Precautions must be observed when using the speaker system. First, do not connect speakers to an amplifier that is turned on. When connecting acoustics, it is impossible to allow so that a short circuit occurs between the conductors. It is not desirable that direct sunlight falls on the surface of the equipment. Also, do not cover the radiator fins on the surface of subwoofers or amplifiers.
Connect the equipment before turning on the power, and set all the main signal level controls to a minimum.
1. Connect one end of the left and right channel signal cable (using a 1/4” TRS Jack or XLR connector) to the main outputs of the mixing console, and the other end of the cable to the main inputs of the active left and right channel speakers.
2. Connect passive speakers to the power amplifier outputs using speaker cables with Speakon connectors.
3. Connect the power cables to the mains.
4. Turn on the power to the mixing console before turning on the power to the speaker amplifiers.
5. Use the controls to set the desired volume level for the active speakers.
6. Using the PFL function, adjust the input levels on the mixing console, and adjust the output level of the main mixing bus.
7. When finished, turn off the power to the active speakers before turning off the power to the mixing console.