Requirements for elements of stereophonic sound reproducing devices. About the possibilities of expanding the stereo effect zone Stereophony and stereotypes

HIGH FREQUENCY

ACOUSTIC UNIT WITH A CIRCULAR DIRECTIVE DIAGRAM

G. STEPANOV

A big disadvantage of modern dynamic loudspeakers is their sharp directivity characteristic in the region of higher sound frequencies, which creates certain inconveniences when listening to monophonic programs and narrows the stereo effect zone when using conventional speaker systems in stereophony.

In various domestic and foreign literature, a figure (Fig. I) has been repeatedly presented, illustrating the influence of the location of loudspeakers on the stereo effect zone. To expand the stereo effect area, many fans of stereophonic sound reproduction use one or two closed-type loudspeakers in each channel, placing them in the corners of the room, as shown in Fig. 2.

High-frequency acoustic units produced by a number of foreign companies are made in the form of a cube, on the inside of each face of which a loudspeaker is located (6 pieces in total).

The use of omnidirectional emitters not only expands the stereo effect area, but also allows you to significantly reduce the required room area from 18-20 to 12-

Rice. 1. Areas of noticeable stereo effect:

a - when placing single loudspeakers in the corners of the room b - when placing a system of three loudspeakers in each channel along the narrow side of the room.

Rice. 2. Place speakers in the corners of the room.

The author of the article proposes the design of a high-frequency acoustic unit with a circular directional characteristic in the horizontal plane, with an operating frequency range from 5-6 to 18-20 kHz.

The design uses domestic loudspeakers 1 GD-3 RRZ with the following main parameters: average standard sound pressure 0.3 p!m2, natural frequency of mechanical resonance 4.5^ ± 1 kHz, total electrical impedance module at a frequency of 630 Hz - 12.5 ohm, rated power 1 etp, operating frequency range 5-18 kHz.

The general view of the unit is shown in Fig. 3. The spherical front of the sound wave from loudspeaker 1 (the figure shows a section of the loudspeaker diffuser) falls on the dispersing lens 2. The sound vibrations reflected from the lens have a circular directional characteristic in the horizontal plane. Calculate the generatrix of the lens

tan in such a way that the directivity characteristic of the loudspeaker is repeated in the vertical plane. To increase the sound pressure and expand the directivity characteristics in the vertical plane, the unit uses two loudspeakers.

When assembling the unit, the loudspeaker with a nylon mesh 6, which protects it from dust, is glued to the plate 4 and the ring 5 pressed into it. Then the entire assembly is attached to the housing 3 using stands 7. Stands 7

Rice. 3. General view of the acoustic unit:

1 - loudspeaker; 2 - acoustic lens; 3 - body; 4 - duralumin plate; 5 - ring; b - nylon mesh; 7 - racks: 8 - base; 9 - couplings.

RADIO No. 4, 1973, O 39

[ 20 ]

2 8; 3.0 m when the DL changes within the range from O (omnidirectional loudspeakers) to (in steps of 2 dB) and for angle values t) from O

The results of these calculations, obtained for B = 3.0 m and DA = 10 dB (as those of greatest interest), are presented graphically in Fig. 3.2. Here

Rns 3 1 for calculating the stereo effect zone

For each individual case, the calculated values of \avg and p are given. The stereo effect zone is shaded, and the zone of the listening seats for which the calculation was performed is left blank. Note that at B = 3.0 m, the greatest increase in the stereo effect zone is observed at DL = 40 dB and \j 70°, which corresponds to an angle to the loudspeakers of 2ph 140°. Zavn-

Fig. 3 2 Influence of the shape and orientation in space of the directivity characteristics of loudspeakers on the size of the stereo effect zone

The symmetry of the coefficient p on the degree of directivity of the AL loudspeakers, obtained for different values of the angles r, is shown in Fig. 3 3.

The data obtained indicate the following: a) the smallest size of the stereo effect zone is obtained when using! directional speakers, but located

Fig. 3 3 Dependence of the coefficient of utilization of the listening area by the tested reproduction system on the degree of directivity of the loudspeakers for different angles of intersection of the acoustic axes of the loudspeakers

so that their acoustic axes are parallel; b) a slightly larger stereo effect zone is provided by omnidirectional loudspeakers! . speakers, c) the greatest expansion of the stereo effect zone is observed when using directional speakers, the acoustic axes of which are directed towards each other at a certain angle.

3.3. Optimal speaker directivity characteristics for stereo playback

The vast majority of currently produced acoustic systems and a significant part of the basic models (see Table 3.1) provide a very narrow stereo effect zone. Firstly, this creates significant inconvenience for the listener, forcing him to position himself on the axis of symmetry of the system. Secondly, the possibility of collective listening in order to obtain a high-quality perceived stereo effect is practically eliminated. For listeners located on the side of the system’s symmetry axis, who perceive only the nearest loudspeaker, the sound essentially becomes monophonic.

This drawback, inherent in most stereophonic sound reproduction systems, is not insurmountable. From Fig. 3.2 and 3.3 it is clear that the use of directional and specifically oriented loudspeakers can be a fairly effective measure for expanding the stereo effect area. In other words, using the directivity characteristics of loudspeakers, it becomes possible to compensate for the effect on the hearing organ of the time difference \Xx,y and the level difference ALx,y by creating at each listening point a compensating level difference of a certain value and sign.

In this case, the compensation equation has the form

;.D.,.+ DH.+ DD(F., = 0 (3-2)

where ДLдф is the compensating level difference, in decibels, created at a given point due to the difference in the directional characteristics of D1(1) and D2(11;2) loudspeakers, and is defined as

D Ld = D, W - D, W = /S. + 20 Ig + /Co

Typically, the values of ДЛд(ф) are calculated only for the central KIZ, since stabilization of its location during the lateral displacement of the listener is a necessary and sufficient condition for stabilizing the entire panorama. This follows from the fact that the slope of the curves characterizing the relative displacement of the KIZ in the AL or Dt function does not depend neither from the size B, nor from the listener’s coordinates at y>B.

From (3.3) it follows that there are many forms of optimal directional characteristics, since the determining factor is their difference. Most often in practice, two ways of obtaining the difference DLdf are used:

The most common method for two-channel stereophony is the creation of loudspeakers that provide for each listening position the values of the difference in directional factors that ensure directional radiation of sound only in the horizontal plane. In this case, in the vertical plane, sound radiation should be as non-directional as possible.

Obtaining the directional characteristics of each of the loudspeakers in the horizontal plane, which is monotonic as a function of the angle and, moreover, without sharp bends, is possible if precise compensation (complete neutralization of the effect on the hearing organ) of the values of Axx.y and \Lx,y is carried out only for points forming a straight line line parallel to the speaker base.

The results of calculations Add1(φ) for different values and distances уо are presented in Fig. 3.4. For ease of comparison, each curve obtained was normalized and, in addition, they were plotted in decibels. From Fig. 3.4 it follows that the shape of the optimal directivity characteristics of loudspeakers depends on V0 and B; the larger B and the shorter the distance to the co.m-yaeisacin line, the sharper the directional characteristics of Gr1 and Gr2 should be;

O -5 -10 -15 dV -20 -15 -10 -5 O

Fig, 3.4. Optimal directional characteristics for the transmission of spatial information for the right (solid lines) and left (dashed lines) loudspeakers of a stereophonic acoustic system for different bases at yb = 2 m (a) and different Uo prn B = 1.8 m (b)

prn!/o>1.5 m the influence of this factor is significantly reduced; the acoustic fundamentals of loudspeakers with optimal directivity (depending on the selected values of B and y) intersect on the axis of symmetry at an angle of 80-120°; the change in directionality of each loudspeaker within an angle of 60°, counting from its acoustic base for cases of greatest practical interest (B = 2.8-3.0 and Uo>\.5 m), is 6-8 dB. Note that the results of these calculations agree quite well with the data in § 3.2. To reduce the influence of the vertical directivity of such loudspeakers and the results obtained, the loudspeakers should be located at the level of the listener's ears, but if the vertical directivity is insignificant, then the height of the speakers is indifferent. You just have to remember that their extreme rise leads to an unnatural height of the stereo panorama.

Another, less common currently method of expanding the stereo effect zone (equally suitable for stereophony and quadraphonics) is the use of loudspeakers that have a certain form of directional radiation in the vertical plane and no directionality in the horizontal plane. To obtain the desired effect, the speakers should be installed lower (this is the preferred location).

Built-in acoustics in residential premises are usually used to reduce clutter in rooms and not to introduce objects that are alien in appearance into the interior. The first is especially relevant in cramped rooms filled with objects - a kitchen, a bathroom - and the latter in interiors of laconic styles.

However, few people know that built-in acoustics can also significantly improve the sound quality of small rooms with unimportant own acoustic parameters, using inexpensive speakers with an average level of sound reproduction fidelity. Why? Built-in acoustic systems (AS) for such purposes, in principle, cannot be manufactured for sale with delivery to the installation site; they must be made directly in the room; as a rule, in the order of simple construction repairs. The purpose of this publication is to provide the reader with information that will allow both the correct installation of a purchased built-in speaker, and the installation of a homemade one into wall cladding, a false ceiling, an arch, or other plasterboard structures or furniture.

Constructions

Based on the design methods, built-in home acoustics are divided into 2 large groups: integrated and modular built-in. The latter is produced in the form of speakers in a flattened housing or broadband monoblock sound emitters (ISM), see Fig. Modular built-in speakers with formally the same technical data are significantly more expensive than those installed separately, and the sound is noticeably worse. The reason is that the overall depth of a modular speaker should not be greater than the thickness of the wall cladding; usually 60 or 80 mm. Therefore, firstly, in speakers for modular speakers it is extremely difficult to use powerful and complex magnetic systems that provide a long cone stroke and the best sound quality. Secondly, the proportions of the body are far from optimal. On the other hand, installing modular speakers does not present the slightest difficulty: they cut out an opening in the casing according to the dimensions indicated on the speaker's passport, take the wires out of it, connect it to the speaker and simply insert it into place: the case is equipped with latches, and there are holes on the front panel , through which they are pressed out if dismantling is necessary. So we’ll finish with modular built-in speakers.

IZShM – sound reproduction systems of medium or basic quality class. In apartments, broadband sound emitters are used to sound small, cluttered rooms: kitchens, bathrooms, hallways, where there is no point in installing high-quality acoustics. IZShM are produced, as a rule, for installation in plasterboard sheathing and therefore also have a small structural depth. However, the sound of ISMs can be significantly improved by integrating them into furniture; One example will be discussed below.

Integrated Systems

From the point of view of sound production, a built-in acoustic system of an integrated type is inseparable from the structure or piece of furniture into which it is built, i.e. the latter are the acoustic design of the primary sound source (the exciter of the system). The primary sound source can be either an IZHM or a conventional 2-3-way set of GG loudspeakers (speakers) with crossover filters and frequency channel attenuators (in high-end systems). It is integrated speakers that allow you to get high-quality sound in small rooms with mediocre acoustics, because... the dimensions of the acoustic design turn out to be commensurate with the wavelengths of the lowest audible frequencies of sound.

Design and frequency response

The design of integrated acoustics for a home can be done in two fundamentally different ways. If you apply a musical signal to a hygroscopic generator simply lying on the table, then bass (low frequencies, LF) will not be heard: long sound waves from the front and rear surfaces of the diffuser will immediately converge in antiphase and cancel each other out. It is impossible to “jam” radiation from the rear directly on the speaker: firstly, due to the high elasticity of the air locked in a small volume, the natural resonant frequency of the GG will increase so much that the bass will disappear anyway. Secondly, for the same reason, the diffuser will sag and produce overtones, i.e. sound distortion will appear at medium frequencies (MF) in the form of wheezing. The task of any acoustic design of speakers is precisely to either suppress radiation from the rear of the diffuser without significantly increasing the resonant frequency of the main generator and the back pressure on the diffuser, or, by “reversing” the rear radiation by 180 degrees in phase, re-radiate it from the front, or, at least from a region distant from the front side of the speaker at a distance much smaller than the LF wavelengths. Examples of acoustic design of the 1st type are a closed box or shield (acoustic screen) with a sound-absorbing structure; 2nd – bass reflex, labyrinth, passive radiator, etc.

Note: The acoustic design of the speakers is also known, so to speak, combined action - an open box, also with an acoustic impedance panel (ARP), horns of different types. Open boxes are not suitable for modern compression speakers and, like horns, cannot be built into objects/structures flattened along one coordinate. Therefore, we will limit ourselves to mentioning them.

Box

Built-in speakers in furniture are most often made according to the closed box design. A closed box slightly increases the resonant frequency of the GG, but the decline in its frequency response (amplitude-frequency response) towards the low frequencies is monotonous and flat (on the left in the figure), which makes the sound more transparent and soft. This is important in rooms with poor acoustics – kitchens, bathrooms. No less important is the fact that a closed box can be made airtight: in combination with a moisture-resistant speaker (see below), you can get speakers that can withstand harsh operating conditions for a long time.

Shield

The acoustic screen theoretically does not affect the natural frequency response and the resonant frequency of the GG. On a standard screen of a special design, technical data of the GG is recorded in sound-measuring chambers. However, speakers on a panel built into the wall are susceptible to dust and, possibly, climatic factors if the building is not properly insulated from the outside, so it is advisable to install speakers of the same design on the panel board as in the kitchen/bathroom (see below) . Due to the impossibility of using powerful complex magnetic systems in them, the intrinsic quality factor of such GGs is Q>0.7, which is why the frequency response at low frequencies no longer falls monotonically, but without large dips, in the center in Fig. Over 95% of listeners, incl. ordinary musicians do not notice any deterioration in sound quality because of this.

With phase reversal

Speakers with rotation of the phase of the rear radiation make it possible to obtain the maximum sound output of the main speaker at low frequencies, incl. and at frequencies below its own resonant speaker. The price of this is the “humpbacked” frequency response and its sharp decline at low frequencies, on the right in Fig. In relation to built-in speakers, there is also intensive air exchange with the room (except for systems with a passive radiator). Therefore, it is undesirable to make integrated speakers with a phase rotation of the rear wave.

Note: If you are a fan of Heavy Music (the Doors group), early Pink Floyd, heavy rock and metal, then you just need small-volume speakers with a bass reflex or horn ones - they have the most “angry” sound.

About the in-ceiling speakers

In-ceiling speakers are used in home theater sound systems, which we'll talk about at the end. But building speakers into the ceiling also makes perfect sense for listening to regular stereo, at a height of no more than 2.5 m. The fact is that a person is poorly able to determine the localization of sound sources by height. Bass differs somewhat better in the height of the source (due to resonance in the body cavities, by the way), but they do not create the main stereo effect.

In small rooms, the area of full stereo effect is very small, pos. 1 in Fig. If you lift the speakers up, positioning them at an angle, then the “tail” of the stereo zone, due to the same upward lift, will contract in projection onto the floor (pos. 2), and the real stereo effect zone will expand, pos. 3.

Living room, bedroom, etc.

Making integrated acoustics in living rooms makes sense, first of all, economically. Why - see prices for modular speakers. It's even better if the wall on which the speakers will be placed is insulated from the outside or adjacent to the adjacent room. In this case, if the acoustic casing is done correctly (see below), you can simply take the board (front panel) from the old speakers along with the speakers and crossover filters and place them in the wall. The required volume of air behind the board is easily obtained by installing horizontal partitions. The main task in this case is to sheathe the wall so that the drywall does not resonate.

Sheathing diagrams for covering walls with plasterboard with installation of built-in acoustics for music and a TV with a subwoofer (bass speaker common to both channels) are shown in Fig. The acoustic design is combined - a shield with an absorbing structure, it is formed by perforated laths of the sheathing together with cavities between them, and/or a closed box. The size of the lathing cells is no more than 400x400 mm. The installation step for drywall fasteners is no more than 80 mm. If the cavities behind the casing are filled with mineral wool (preferably with padding polyester, see also below), the sound will only improve. The inclination of the corner sections relative to the base wall is 10-30 degrees. The sheathing is single-level, its slats cut into half the tree at the crosshairs. The perforation channels of “leaky” sheathing slats should be located parallel to the wall. Since there are no bass speakers with a design depth of 40 mm, a box extension must be built under the subwoofer from solid slats or boards 40 mm thick. Speakers acc. The sheathing cells must be mounted on boards with a thickness of 20 mm or more.

About the volume behind the speakers

If speakers with filters from an old speaker with a bass reflex are installed in the described acoustic design, then the entire frame will need to be assembled from solid slats, and the volume behind the speakers will be adjusted to the value in the original speaker using horizontal partitions, because otherwise the operation of the bass reflex will be disrupted.

If speakers from old closed-box type speakers are installed, then the volume behind the corner speakers in the wall must be recalculated to the maximum permissible using one of the known methods or use a simplified one (see below). The fact is that in production, incl. in very reputable companies, designers, marketers, economists and ergonomists often put pressure on designers, forcing them to make speakers - closed boxes of volume much less than optimal. For example, the volume of a potentially very good 6AC-1 was made 6.5 liters based on a certain category of consumers, and the technically optimal volume for those speakers was 30 liters. The sound of the same speakers with filters in a suitable box changes amazingly - not for the worse.

Bathroom

It is obvious that a bathroom needs moisture-resistant acoustics. The prices for “waterproof” speakers in the Hi-Fi category in branded price lists are also obvious and can cause a storm of various emotions, except joy. So, the task before us is to make fairly high-quality built-in acoustics for the bathroom, making do with more affordable speakers.

Speakers

The operating conditions for acoustics in a bathroom are quite similar to those in a car. The differences are that in a bathroom, 100% air humidity at elevated temperatures occurs much more often, and it is possible that water splashes on the speakers regularly. It follows that we need to select car speakers for the bathroom that are as moisture-resistant as possible “from the front”, and from the rear to protect them from fog and condensation, because The most vulnerable parts of any speaker to climatic influences are the coil and magnetic system.

Speakers for homemade bathroom acoustics must, firstly, have a plastic diffuser. The sound they give is up to four (on a five-point scale) with a small plus, but in a hygienic bathroom you can’t count on the best. Let's leave clapboard bathrooms by default: they are healthier for germs and spiders than for people. In relation to operating conditions in the bathroom, you will have to additionally pay attention to some design features of car speakers, and how to choose them based on technical data, see the video below.

Video: choosing car speakers for installation according to technical requirements. characteristics

To increase the resistance of speakers to the bathroom microclimate, you need to use speakers either broadband or monoblock IZHM; There should be no separation filters in the speaker housing. If the speaker is an IZHM, then the diffusers of all links (woofer, midrange, tweeter) must be plastic or metal (metalized), the midrange-HF links must be located on a moisture-resistant mounting module, and the wiring to them must be hidden (on the left in the figure) ; auto speakers, the diffuser of at least one link of which is made of cellulose, and the wiring to the midrange-high frequencies is open (on the right in the figure), are not suitable for the bathroom, even if they sang in the car interior, like the Alexandrov choir at the Bolshoi Theater.

Box

It is possible to protect the rear of the speaker from the bathroom climate by using a closed box acoustic design. AC drawers will have to be built either into corners, side or top, under the ceiling, or into bathroom furniture: a wardrobe, cabinet, dressing table.

The correct proportions of a closed box for acoustics are given in pos. 1 Fig., and the minimum permissible volume for broadband and auto speakers with a long-term power of 6-20 W (20-60 W musical) can be taken approximately (in liters) equal to 1.4 long-term power or 0.47 musical (peak). We take the maximum permissible volume equal to 1.8 peak power or 5.4 long-term power. Please note that the speaker is not installed exactly in the center of the front panel: this is necessary to avoid sound distortion due to interference from sound waves inside the box. If the volume of the box is closer to the minimum, the sound in the midrange will be louder and clearer, but the lower limit of the reproduced frequencies will shift upward, i.e. deep bass will be muffled or attenuated. If it’s closer to the maximum, it’s the other way around.

Note: you need to understand the power of the speakers according to the specification, because There is inconsistency in the notations. For example, 10GDSH-1 has become 10GD-36K in a new way, and “10” denotes its long-term power in watts. But the 25GDN-1-8-80 has a long-term power of also 10 W.

Case material – MDF or plywood with a thickness of 18-24 mm. Parts from both are soaked through and through with a water-polymer emulsion 2-3 times. The assembly of the “closed box” acoustic system for the bathroom is carried out as follows. way:

The box is assembled using silicone glue and corrosion-resistant fasteners without a front wall (front panel);
A cable is routed through the rear (side) wall and out of the opening for approx. by 0.5 m, and the cable entry is sealed with silicone;
The filling is inserted into the body (see below);
In the opening with an indentation from the edge to the thickness of the front panel, a mounting frame made of a rail from 20x20 to 40x40 is attached for it;
A speaker is installed on the front panel;
The joint between the speaker housing and the front panel is sealed with silicone;
The wires are soldered to the speaker terminals. Does not fit into standard clamps! And watch the polarity (phasing), you won’t be able to correct it later! Solders are protected with nitro varnish;
Silicone glue is applied to the mounting frame with a snake;
The front panel with the speaker is installed in place and secured with nickel-plated or chrome-plated fasteners: in the corners, in the middle of the short sides and 2 fastening points on the long sides;
The window with the speaker diffuser is covered with a protective micromesh, for example, from a piece of women's tights on a frame;
A splash guard is installed (see below);
The speaker is varnished twice with acrylic varnish and installed in place.

Filling

Built-in acoustics for the bathroom should be as compact as possible, and the means to increase the physical volume of the drawer against the geometric one have long been known. To do this, a loose roll of synthetic padding polyester is placed vertically into the speaker housing, pos. 2 in Fig. The filling will absorb the energy of the internal sound waves, causing the thermodynamic process in the box to become isothermal rather than adiabatic. This is equivalent to increasing the volume of the box by 1.4 times (adiabatic exponent). That is, we estimate, as described above, the volume of the box, divide it by 1.4, then, using the obtained value and the proportions of the box, we calculate its internal dimensions, and from them and the thickness of the material, the external and dimensions of the parts.

Lens blinds

Together with the micromesh, it will reliably protect the speaker from splashes of blinds made from rigid moisture-resistant plates inclined downward at 45 degrees with a polished surface (to avoid sound distortion), pos. 3. Blinds can be installed across the entire width of the front panel, and its height above the window for the speaker is unlimited. The installation pitch of the plates is 12-18 mm. It would also be rational to make blinds in the form of an acoustic lens, expanding the stereo effect area, which is important in the bathroom. The pattern of the plates for the lens blinds is given in pos. 4.

Box for the frisky

Relatively inexpensive, moisture-resistant, low-power broadband speakers with a short cone stroke; inexpensive car speakers are often of the same type. American radio amateurs nicknamed such speakers “sharp” for their high sound volume with low power input and a hard, sharp sound. The reason for the latter is the large unevenness of the frequency response throughout the entire operating range.

In recent years, the sound of “frisky” ones has become much better: manufacturers began to add finely chopped silk threads to the mixture for casting the diffuser, but for moisture-resistant “frisky” such a solution is not applicable, because their diffusers are molded from plastic. However, it is possible to make the “high-spirited” sound at the level of basic Hi-Fi. Apart from the dynamic range, but in a small bathroom or kitchen this limitation is not significant.

First, the “fast” speakers are combined in phase into quadruples. In addition to some smoothing of the frequency response, the resonant frequency of the quadruplet turns out to be approx. 1.7 times lower than a single speaker from it. That is, one will have 110 Hz, and the quadruplet will have 65 Hz, which already resembles Hi-Fi. But you shouldn’t get carried away with “reproducing” speakers, because At the same time, the clarity and strength and “elasticity” of the bass decreases. For example, if 24 speakers with a resonance of 150 Hz are crammed into one box, then the final resonant frequency will be 20 Hz. However, only a sinusoidal signal will correctly reproduce this crowd, and if you give music, then there will be an indistinct uterine hooting, in which the musician will not be able to tell where the bass drum is and where the double bass is.

In addition to combining into fours, you can improve the sound quality of the “high-spirited” ones by placing the quadruplet in a triangular-shaped body. For built-in speakers, this is all the more good since both side and ceiling acoustics are implemented in this way. Drawings of the “Four Frisky” acoustic system developed by American radio amateurs are given in pos. 5 fig. Note that the quadruplet axis is also offset from the center of the faceplate. Dimensions are on the inside. Filling with synthetic padding improves the sound, as in a rectangular box.

Kitchen

In the kitchen it is convenient to listen to music from a kitchen radio player with standard speakers, pos. 1 in Fig., which are probably the same “frisky” with silk. In general, such equipment is inexpensive, and you can get quite decent bass from it by building speakers into the back of the kitchen corner, pos. 2. If you have a desire to make a kitchen corner exactly like your kitchen with your own hands (which is quite possible for an ordinary home craftsman), think about this option.

The cavity behind the back of the sofa is tightly fenced off at the top, bottom and sides, and in the middle it is partitioned off with a blank partition (item 3) so as not to spoil the stereo. The drawers are filled with padding polyester, and fiberboard is sewn up at the back. To make the stereo in a small cluttered room clearer and the sound richer, the upper corner above the acoustics (under the ceiling or hanging cabinet) is rounded with plasterboard or plywood, at the top at pos. 2. A similar technical solution was first used in the once widely known Kyuhetta AS. Unfortunately, the “Cuhetta” stereo was never born: it required two completely free adjacent corners on a short wall, which is hardly realistic in modern apartments.

5-1 and cinema

For home cinema, as is known, 5-1 system acoustics with additional ceiling speakers are used. Its creator, the outstanding, even, without exaggeration, great sound engineer Charles Dolby, more than once complained that 5-1 was too zealously snatched for commercial use. It was he who came up with 5-1 acoustics for the full-scale cinema of the future, where the viewer, in theory, will be able to walk around the stage, viewing the characters and the environment from all sides. 3D cinema is only an illusion of volume; in essence, this is an improved stereo pair. Like 5D, 7D, 9D. Where are the science fiction writers of the past with their unfortunate fourth dimension? But all these “Ds” are no more voluminous than an isometric image of a cube.

5-1 sound can, of course, revive a film on a flat screen, but this requires a completely different production culture, which does not yet exist in theory. And the sensations of a car passing through the viewer or stomping behind one’s back while the character is running in front of one’s eyes do nothing but harm one’s mental and, through it, physical health. But let’s return to technology: if someone has acquired a home theater, then you need to adjust its acoustics to the room correctly, the 5-1 system is very critical to this.

The arrangement of speakers for a home theater with a 5-1 sound system is shown on the left in Fig. Its basis is the so-called. drawing speakers (shown by red arrows), forming a regular acoustic stereo pair. Setting up 5-1 for the room is done by selecting their correct location, so the 5-1 sound speakers should not be built-in, or you need to initially design the 5-1 for the room. Which requires complete knowledge of electroacoustics in theory and practice, or very, very significant funds.