Refinement of the S90 or how to make them “sing” at minimal cost. Speakers S90: technical specifications, diagram. DIY speakers What speakers are in the s90 speakers

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Modernization of S-90 speakers by replacing standard cabinets with labyrinthine design of bass speakers

Upgrade of the S-90 labyrinth design by stuffing the corners with cotton wool and sticking them on the inner surface of the wool blanket
At first, only the frontal knees of the labyrinth were covered with wool, then the side surfaces too
Ready labyrinth S-90 with inner surfaces covered with wool

Remaking the most famous speakers of the USSR Radiotekhnika S-90

Alexander Rogozhin came up with the know-how of how to convert the Radiotekhnika S-90 speakers, most well known to most Russian-speaking people, into labyrinthine housings. The article is devoted to the most widespread and for more than 20 years considered the standard acoustics of the Soviet period, which in its first generation was called 35AS-1. And Rogozhin proposes to make speakers from 35AC-1 (Radio Engineering S-90) with the name “Cheap, loud and super-bass”!

Ode to speakers Radiotekhnika S-90 (35AC-1)

There is no person who speaks Russian, Ukrainian, or Belarusian, who has not heard the famous Soviet Radiotekhnika S-90 speakers at least once in his life, or who has not had one of their modifications produced in more than 30 years. You can think whatever you want about their sound, appearance, rubber speakers, but in fact these are the MOST common “People’s” speakers in the vast expanses of the former USSR. Even now, tens of thousands of them work in the systems of music lovers, who feel sorry to throw them away because Compared to the branded “remake” they play very, very well.

If a person is faced with a choice on which speakers to listen to music on: with bass, loudly, and for ridiculous money, then despite all the disadvantages of the Radio Engineering S-90, they have practically no competitors, and even less so before. In the late USSR, in addition to S-90 speakers, of course, “clones” appeared, taken from the best foreign samples, for example, Electronics 100AC063 or 75AC-063. But they were very expensive and not widely used; they could not compete in popularity with the S-90 acoustics. It was basically impossible to get three full-fledged bands with the same power as the S-90, a 10-inch woofer and almost nothing from any other speakers. This is even more relevant now.

Tens of thousands of these speakers still work in the rooms of young and not so young people who do not have the opportunity to carry out complex projects on expensive imported dynamic heads. For obvious reasons, many of our compatriots are in no hurry to abandon the Radiotekhnika S-90 acoustics. They are not eager to run to the store and buy beautiful branded speakers, which for the most part differ from the S-90 only in appearance, which often cannot be said about their sound.

And yet we all love to listen to music, it happens to everyone good mood, when you want to turn it on “to the fullest.” Everyone loves high-quality bass, without which almost any music loses its foundation and most of its emotions. Many styles of music without bass are generally impossible to listen to, because... without it, the lion's share of important musical information is lost. The soul asks UUUH! And low frequencies are actually a very delicate thing; in order to sound adequately and make an impression, they require large speakers, cabinets and power. But even with all this (in large speakers like the S-90), the bass often turns out to be buzzy, drawn out and indistinct, and does not give us the “buzz” that it is supposed to give. We quickly get tired of such bass and start turning the tone control knobs or switching the equalizer modes on the receiver. And instead of getting pleasure, you get annoyed and think about the imperfections of this mortal world... Almost all music lovers and owners of these acoustics, in particular, have found themselves in this situation more than once.

Low Frequency Problems S-90

The reason that over the past 30 years, owners of the Radiotekhnika S-90 acoustics and its numerous modifications are not satisfied with its sound and are somehow trying to cope with this problem lies in several reasons. The main problem with the S-90 speakers, confirmed by repeated research by specialists, is an error made when designing the low-frequency design of the 30GD-2 speaker. Having entered the series, the error led to the fact that the potential for high-quality reproduction of low frequencies, originally inherent in the Radiotekhnika S-90 model and its modifications, is not realized even by 20-30% of the possible ones.

A huge number of S-90 owners, almost from the moment they appeared on sale in the 80s until today, have been trying to improve the low frequencies of these speakers by conjuring with filters, altering the bass reflex pipes, strengthening the original housings and filling them with anything.

Dear music lovers! I urge you to stop doing nonsense, because... this is absolutely useless... The S-90 speakers from the factory have a housing with a volume of only 45 liters - NOT corresponding to the optimal operating mode of the 30GD-2, 75GDN1-4 speaker installed in it. You can even trim it with the roots of rare species and cover it with porous rubber on all sides - it will still NOT work correctly.

That is, the question of radically improving the performance of these speakers at low frequencies, no matter how regrettable it may be, is that the question of replacing the housing arises in full force.

The task is somewhat complicated by the fact that over 30 years a huge number of modifications of 35AC-1 speakers with 30GD2/75GDN1-4 (8) low-frequency speakers have been released, which have a wide range of parameters. In new enclosures, this problem has been largely resolved and allows speakers from the earliest releases to the latest to feel correct. The setup of new enclosures is “stretched” and allows you NOT to specifically select low-frequency speakers.

Mid Frequency ProblemsS-90

Almost all owners of s-90 speakers note unpleasant overtones and greater unevenness of output at mid frequencies, which become especially noticeable at medium and high volumes. All grandiose projects to remake filters by installing expensive imported capacitors, replacing wires, resistors, etc. as well as options for gluing halves of a tennis ball onto the diffuser of mid-frequency heads, etc. fail.

The main reason for the unsatisfactory sound at mid frequencies is not the 15GD-11 speaker at all, but its acoustic design. This “glass” covering the midrange head from behind has a tiny volume and is the second mistake made by the engineers who designed the S-90 speakers. The “glass” of the mid-frequency head 15GD-11 (20GDS...) has everything wrong, from the volume and configuration to the internal design. When replacing the housing of the s90 speakers with the correct one from the point of view of the design of the woofer, the mid-frequency speaker should also be designed accordingly.

Of course, replacing the “minuscule” standard glass with an acoustic design that is optimal in volume and shape will not make the 15GD11 head a different speaker, but will give it the opportunity to do what it can do initially.

What you can get

As a result, the updated S-90 speakers will sound radically different not only at low, but also at medium frequencies. There are a large number of attempts on the Internet to remake S-90 speakers with the goal of “deceiving everyone” and turning them into studio monitors. Attempts concern everything except replacing the main “weak point” - the body, and most often turn out to be failures. While keeping the S-90 speaker cabinets unchanged, to radically change the sound, you need to change the speakers to modern ones or design three-way speakers from scratch, which most music lovers do not dare to do.

I suggest leaving the original set of S-90 speakers untouched. Their value lies in the minimum budget and, no matter how clever you look, their performance has been proven over decades of operation in the harshest conditions.

One thing that can be fundamentally improved about these speakers is to “get the most out of their speakers.” To do this, you need to make an acoustically correct housing for the original set of speakers and filters. As a result, you can reach a fundamentally new level of sound quality from these speakers without spoiling anything.

As a bonus, you don’t have to throw away the old cases and, if necessary, the “stock” S-90s can be put back together and sold to some lover of authentic speakers made in the USSR.

Problems with native boxesS-90

• The wrong amount of low-frequency design does not provide the required level of pressure on the low frequencies;
• Non-optimal bass reflex tuning frequency leads to uneven bass and bass response. poor quality bass;
• The type of low-frequency design “bass reflex” in combination with a “tight” speaker on a rubber surround leads to an extended and monotonous “hum” at low frequencies, instead of a clear impact bass;
• Phase-inverted acoustic design leads to significant unevenness of sound pressure at low frequencies in the room, and places demands on obtaining high power from the amplifier;
• The weak walls of the S-90 speaker boxes lead to a loss of efficiency at low frequencies and produce noticeable overtones when operating at high volumes;
• Poor sealing of the boxes prevents even the low-frequency design that the S-90 speakers have in the stock version from working;
• The extremely small volume of the cap of the mid-frequency head 15GD11 (20GDS-) leads to “squeezing” of the mid-frequency dynamics;
• Non-optimal damping of a small-volume midrange box leads to noticeable overtones and “nasality” in the midrange;
• The shape and dimensions of the S-90 speaker cabinets in the stock version require their installation on furniture, which leads to a “wobbly position” of the speakers, resonance of the furniture at high volumes and, ultimately, to deterioration in the sound of low frequencies;
• The “low-profile” shape of the speaker housing requires installation on specialized stands for acoustics, which ultimately increases the cost of the system. Installing the 35AC-1 speakers on the floor leads to a lack of high frequencies and an incorrect scene.

Advantages of new buildings

• The design of the low-frequency head is a quarter-wave labyrinth with its radical advantages at low frequencies over a bass reflex (detailed description here);
• The optimally calculated frequency and quality factor of the quarter-wave resonator tuning provide a wide band and optimal level of low frequencies;
• The highest rigidity of the box gives the highest possible efficiency, clean, elastic and biting sound at low frequencies;
• The high-volume, hard-box midrange driver produces a lively, open midrange and clear vocals;
• The placement of the midrange and high-frequency speakers on the front panel, maintaining the distances to the cabinet walls according to the “golden ratio” principle, reduces diffraction phenomena on vocals and high frequencies and makes the sound much more comfortable;
• With the new enclosures, the acoustics transform into a classic floor-standing design with midrange and high-frequency speakers optimally positioned in height;
• The speakers have narrower and taller front panels than standard S-90s and do not require any stands. The appearance of the speakers is improved many times over.

Who doesn’t remember the famous S-90 speakers from the 70s? (In fact, there was the Latin letter S, and therefore this Riga product was called the Radiotehnika S-90 speaker system, but the habit of not trusting everything foreign also came from this time, and then not everyone knew that the Balts use the Latin alphabet.) Dance regulars in the club (called discos in the 80s) they didn’t go into such details, and therefore they still call these speakers S-90. This article will be devoted to the literally legendary acoustics of Soviet times.

Nostalgia

"Radio Engineering S-90" was considered one of best systems of that time and was in demand everywhere. Concerts in cultural centers in the most remote corners of our country, amateur performances, school evenings with songs and dances - everywhere this equipment was indispensable. Some irresponsible comrades risked conducting rehearsals at home, and the S-90 speakers created an unforgettable sound effect in absolutely all apartments of the five-story panel building. The “gratitude” of the neighbors was also indescribable. They can be understood. Even if the owner “turned up” the medium volume, extraneous sounds simply evaporated: the howling of dogs, the knocking of neighbors on the radiators, as well as the sound of sluggish bass from ordinary speakers two floors above disappeared.

The “Radio Engineering” column heralded either an approaching earthquake or a military fighter jet touching the roof in a low-level flight. The chandeliers bounced, the crystal in the sideboards tinkled subtly, and everything in the room that was not secured was clearly vibrating. Although it must be said that the S-90 speakers were not and were not considered the most powerful in their class, an amplifier was installed to them. By the way, working versions of this equipment are in great demand today. Even heavily used retro equipment is quite expensive. A “Radio Engineering” column of any modification in working condition will cost from four thousand rubles. One!

Description

The Radiotekhnika acoustic system of the highest (zero) class 35 AC-1 went on sale in 1977 and was immediately named S-90. The speakers had the best characteristics for those times, especially considering that only Soviet equipment was used. They were developed purely for domestic use, and this was done by the Orbita design bureau at the Riga Radio Engineering Production Association. Subsequently, the entire series of these acoustic systems received the S-90 brand.

The speakers fully justified their characteristics; they were in no way inferior to imported ones, significantly surpassing all domestic ones. In order for the sound of the acoustic system to be complete, an amplifier of the “Electronics” or “Amphiton” type must be connected to it. In the frequency range from 31.5 to almost 20 kHz, the speakers operated with a nominal power of 35 Watts. Moreover, the power in the passport was ninety. The sound pressure, the results of which are described above, was 1.2 Pa.

About the disadvantages

The weight of one column sometimes exceeded thirty kilograms. They cost three hundred rubles per pair (an engineer earned from ninety to one hundred and twenty rubles a month). However, few have seen them on sale for free. Many people bought S-90 music speakers one at a time, despite the fact that there was no guarantee that buying a second one would make them a well-tuned pair. However, even if a pair was purchased, no one guaranteed its balance: for example, the right speaker of the S-90 collected all its power together and persistently sounded louder than the left. This is despite the fact that the equipment was positioned as having the highest category of quality.

This drawback is not the only one that the S-90 column could have. Tweeters often failed because the thin and weak wires themselves were not very practical. At mid frequencies the sound was downright bad and often spoiled the whole impression. Other electronics could not withstand the sound system next to these huge structures, and the magnetic field created by the speakers had a negative effect on humans. And yet it was the S-90 that could ideally create surround sound in ordinary apartment standard panel house. In general, there were no special complaints about the sound.

Installation

The shortcomings that the Soviet S-90 speakers had did not stop music lovers throughout Rus'. For several decades they remained one of the most popular acoustic systems. Many thousands of pages on forums are dedicated to them today. This is one of the most striking symbols of a bygone era, which also had reliability and durability, which modern gadgets do not have at all. The S-90 speakers had impressive dimensions (36 x 71 x 28.5 cm), so they required correct installation, which was not always combined with opportunities.

The apartments were quite cramped (and the conditions are the same now), and therefore you could see the speakers half a meter from the listener. While perfect way for better sound, place them on a pedestal just half a meter high and maintain a distance of at least two meters from the listener’s ear. Rarely does a room have such advantages; most often the required space is not enough, and therefore only the neighbors listened to the real sound that this equipment was capable of.

Appearance

The S-90 speaker has a simple and well-made body - a non-separable rectangular box made of chipboard, trimmed with high-quality veneer from valuable wood. The wall thickness is sixteen millimeters, and the front panel is made of twenty-two millimeter aircraft multilayer plywood. The joints of the walls and internal sides are reinforced special elements, increasing the rigidity and strength of the body.

The heads have decorative black frames stamped from aluminum sheet. They are also protected by a metal mesh. On the front panel, the mid-frequency head is insulated inside with a cone-shaped plastic casing, the low-frequency head is located along the vertical axis. At the bottom of the column there is an overhead plastic panel with a nameplate. There is also a hole 100 x 80 millimeters - this is the bass reflex output. The amplitude-frequency response (AFC) is displayed on the nameplate, all curves correspond to the positions of the regulators. There is also the name of the speaker system and the brand name. The above-described frame with fabric is attached to the front panel with bushings. On back wall at the bottom there is a block with terminals.

Inside

The internal volume is filled with a sound absorber made of technical cotton wool, covered with gauze. In this way, the influence of sound pressure on the frequency response is reduced and a better sound quality of the speaker is achieved by eliminating resonances in the internal volume. Inside the case there are electrical filters on the board that separate the strips of the speaker system. The kit also included four plastic feet designed to be attached to the base of the cabinet, as well as a decorative removable frame with knitted fabric that adds acoustic transparency.

A rare acoustic system of those times has such qualities as the S-90 speakers - the sound power is simply off the charts! But at close to the maximum volume, the low frequencies become inaudible and booming, and the highs begin to click - this characteristic feature high-frequency heads 6GDV-1-16. A little later, when similar products began to go on sale - “Amfiton 35AS-018”, “Orbita 35AS-016” and others, a different head was used. Sometimes analogues of this speaker system provided a deeper and more balanced sound than the original S-90 speakers.

S-90 line

All modifications of the S-90 and even all its analogues were certainly aimed at using cassettes. The high-frequency head reproduces sound quite well in the upper frequency range thanks to the cassette deck and Soviet amplifier. But if the lower and middle parts of the high frequency range are reproduced just fine, then the very top is different from them, and therefore receives criticism for allegedly blocking the frequency response and unevenness.

And the “Orbita” column of the S-90 line from the Moscow plant turned out to be a truly worthy alternative to the Riga “Radiotekhnika”. This modification with a similar set of acoustic heads differed only in the presence of a two-tube bass reflex at the very bottom of the body. As a result, the bass became lower and thicker. However, at high power, problems with hum and inaudibility persisted, and the upper frequencies clattered in exactly the same way as with the Radiotekhnika S-90.

Manual upgrade

Many music lovers finally realized their own dream: they bought the legendary S-90 speakers and began to modify them with a file. The solution is budget-friendly, exciting, and then the sound is the envy of everyone. Over the past thirty years, the outside of the speakers, of course, has lost its former chic in almost a hundred percent of cases, but the main thing here is that no one messes with the inside. You need to start working by enriching your arsenal with tools. You will need a basic set of screwdrivers, pliers, and a soldering iron. The first step is to remove the front panel, for which you need to unscrew a dozen or two different screws.

When disassembling, it is necessary to check whether the filling corresponds to the passport. So that at high frequencies it would be 10GD-35, at medium frequencies - 15GD-11A, and at low frequencies, for example, 35GD (well, or whatever is stated in the passport). Speakers are most often damaged, since it is possible to destroy equipment within one day, and even more so in thirty years. For example, a lot of furniture rearrangements and moves could happen. Most likely something is damaged. For example, a woofer. Resuscitating him will require additional work. You need to rewind the reel. In principle, this is not so difficult if you know some of the subtleties and have encountered the rewinding process at least several times before. After winding, centering and drying, the sound of the speaker will be perfect - all extraneous sounds will disappear.

Domes

S-90 speakers, as everyone knows, most often disappoint with the sound of high frequencies - with overtones. And at mid frequencies there is often no ringing. Craftsmen recommend basically the same thing: replace the midrange, treble and dampen the body. But it’s better not to look for easy ways. The speakers are simply covered with plastic domes. This material is completely unsuitable.

Silk domes will remove overtones and make the sound more transparent. Therefore, the speakers can be safely replaced. While one speaker is being upgraded, it is necessary to test the sound and compare it with the one that is just waiting for the upgrade, that is, with the original one. Then it becomes absolutely clear whether to leave the rework or return everything as it was. The main thing is that the owner of the speakers and golden hands also has good hearing.

Wiring and housing

To improve the sound of low frequencies, the housing needs to be modified. Down with cotton gauze mattresses! Stores sell inexpensive batting that makes an excellent filling pad. And for just over a hundred rubles! All this can be done quickly and without any effort: the width of the batting is two meters, enough for two columns, but you will need a furniture stapler or a friend who has one. Before installation, just in case, it is better to change all the wiring and remove the switches. Cut out the batting in two layers and boldly sheathe the body.

The bass reflex pipe is placed on the sealant, and after that it is also covered with batting. There is also not much work to do directly with the filter. The switches will never be needed, so they can be removed, like all unnecessary elements from the board. Replace all these thirty-year-old thin wires with normal copper ones at all connections. Next, the filter, freed from everything unnecessary, must be carefully installed in the housing and covered with batting. The entire midrange box on the outside should also go under the material mentioned above.

Results

Judging by the reviews of home craftsmen, such simple modifications have changed the sound of the equipment for the better simply beyond words. The bass became clear, the top became transparent and light. After replacing the speaker, the vocals sounded completely different in the midrange.

35AC-012	35AS-1 (35AS-201)	35AS-212
S-90B	S-90B	S-90D, S-100D
S-90E	S-90F

Production of the three-way acoustic system "35AC-012" (S-90) began in 1975, "35AC-212" (S-90) since 1980. Bryansk Electromechanical Plant and Riga Radio Plant named after Popov. Price 1984 S-90 (35AC-212) – 150 rub.

The range of sound frequencies effectively reproduced by the acoustic system consists of the frequency response of three loudspeakers: low-frequency type - 30GD-2 (75GDN-1-4/8 or 75GDN-3), mid-frequency type - 15GD-11A (20GDS-1-8 or 20GDS- 3) and high-frequency 6GD-6-25 (6GDV-6-16 or 10GD-35 or 10GDV-3) which, with their frequency response, complement and equalize the overall amplitude-frequency characteristic of the acoustic system, which is equal to - 25...25,000 Hz. Speaker input impedance 3.2 ohms. Speakers with an input resistance of 7.6 ohms were also produced. The speaker casing is non-separable, with the exception of its front panel; the speaker casing is made of 16 mm thick chipboard. The front panel of the speaker system is made of plywood, 22 mm thick. A special frame with dark fabric can also be placed on the front panel to give the speaker system a household, rather than technical type. The speakers were produced in a mirror version. The speaker has a bass reflex tuned to a frequency of 31 Hz. The bass reflex output is located in the lower corner of the housing. The speaker has switchable frequency response controls for midrange and treble, which are located opposite the corresponding heads. Speaker dimensions 360x710x285 mm. Weight 30 kg.

Purpose and scope: for high-quality reproduction of music and speech programs in stationary living conditions (performance category UHL 4.2 according to GOST 15150-69). The S-90 acoustic system, developed in 1975, is the first domestic system that meets the requirements of international documents for Hi-Fi equipment.

The acoustic system 35AC-1 (35AC-201), developed at the beginning of 1977 by the Orbita design bureau of the Riga Radio Engineering Production Association, became the second speaker in the whole S-90 series.
It was used to complete the Viktorija 003 radio and the Allegro 002 electrophone, and was first shown at the Svyaz-75 exhibition. At that time, it was the best not only among domestic speakers, but also sounded better than many speakers from foreign companies. The speaker system has two step playback level controls for mid and high frequencies in the ranges of 500...5000 Hz and 5...20 kHz, respectively. Both regulators have three fixed positions: “Max”, “Norm” and “Min”. In the "Max" position, the signal is supplied to the HF head directly, and to the midrange - through a sound pressure equalizing resistor. In the “Norm” and “Min” positions, the signal is attenuated relative to the “Max” position by 3 dB (1.41 times) and 6 dB (2 times), respectively. By switching the knob you change the timbre of the sound. To manipulate the switches, the decorative front panel must be removed.
Price 1978 35AS-1 – 110 rub.

Later modifications of this acoustic system “S-90B” and “S-90D” are distinguished by an expanded range of reproduced frequencies, the introduction of an indication of electrical overload of loudspeakers and a new appearance. The recommended power of a high-quality household amplifier is 20-90 W. The preferred installation option is floor-mounted.
Price 1989 S-90B – 150 rub.
Price 1990 S-90D – 160 rub.

A distinctive feature of the “S-100B” acoustic system is the use of a loudspeaker with magnetic fluid “MANID” as a mid-frequency link, which made it possible to increase the rated power of the loudspeaker and the speakers as a whole. Specifications: Cr3.843.050 TU.

The Bryansk Electromechanical Plant produced a version of the 35AC-012 speakers called S-90E, externally similar to the SOYUZ 50AC-012, but with a different filter circuit, produced by the same company with a 75GD-3-4 low-frequency speaker on a PPU suspension.

S-90 clones with a similar set of heads were also produced, such as 50AC-012 Soyuz, 35AC-202 Romantika, 35AC-211 Amphiton.

Sound System ModificationsS-90:

Specifications

Frequency response graphs

Shape of the frequency response of sound pressure measured along the acoustic axis S-90 (35AC-012, 35AC-212)

Shape of the frequency response of sound pressure measured along the acoustic axis S-90B, S-90D, S-100B

Design Features

The casings of all modifications of the speakers are made in the form of a rectangular non-dismountable box made of chipboard veneered with valuable wood veneer. The thickness of the case walls is 16 mm, the front panel is plywood 22 mm thick. At the junctions of the housing walls and on the inside, elements are installed that increase the strength and rigidity of the housing.
The following sets of heads are used in acoustic systems:
S-90: 75GDN-1-4/8; 20GDS-1-8; 6GDV-6-16;
S-90B, S-90D: 75GDN-1-8; 20GDS-1-16; 6GDV-6-25;
S-100B, S-100D: 75GDN-1-8; Z0GDS-3; 6GDV-6-25.

The heads included in the AC “S-90” are each framed with decorative blackened overlays, made by stamping from aluminum sheet, with four mounting holes. The midrange head is isolated on the inside from the total volume of the housing by a special plastic casing in the shape of a truncated cone. The LF head is located on the front panel along a vertical axis, and the MF and HF heads are shifted relative to this axis to the left or right. On the front panel there are also knobs for midrange and treble level controls, and in its lower part there is a plastic overlay panel with a nameplate and a rectangular hole (100X80 mm), which is the bass reflex output. The nameplate shows frequency response curves corresponding to various positions of the level controls, as well as the name of the speaker and the manufacturer's logo. In addition, the front panel has special plastic bushings for attaching a decorative frame with fabric.
On the back wall of the S-90, in the lower part, there is a block with special terminals used to connect the supply wires. Each head on the front panel side is protected by a blackened metal mesh to prevent damage during transportation and operation.
The heads included in the “S-90B” and “S-100B” are framed by two decorative overlays made of plastic and then painted “metal” or black. One trim frames the midrange and tweeter heads, as well as the upper half of the front panel, the other – the woofer head and the lower half of the speaker front panel. The midrange, tweeter and bass heads are protected by metal meshes. Each of the overlays is secured with six decorative screws. The midrange head is isolated on the inside from the total volume of the housing by a special plastic casing in the shape of a truncated cone. The heads are located on the front panel along the vertical axis of symmetry of the speaker. The nameplate at the top of the front panel shows the sound pressure frequency response curve and gives the name of the speaker. In the upper right corner of the front panel there are speaker overload indicators by channel, and in the lower part there is a rectangular output hole (35X108 mm) of the bass reflex, the tuning frequency of which is 25 Hz. On the rear wall of the speaker there is a nameplate with the main technical characteristics and a block with clamps for connecting the connecting cord, as well as sound pressure level controls at medium and high frequencies.
The heads included in the “S-90D” are each framed with decorative overlays and protected by a mesh; The arrangement of the heads is similar to that in the “S-90”. On the front panel, in addition, there are: indicators of overload of the loudspeaker heads, regulators of the sound pressure level of the midrange and high-frequency loudspeaker heads, and a nameplate with the name of the speaker. At the bottom of the front panel there is a rectangular output hole (95x75 mm) of the bass reflex, the tuning frequency of which is 31 Hz. The front panel also has plastic bushings for attaching a decorative frame with fabric. On the rear wall of the speaker there is a nameplate with the main technical characteristics and a block with special clamps for connecting the connecting cord.
The internal volume of all modifications of the AC is 45 dm 3. To reduce the influence on the frequency response of sound pressure and the sound quality of speakers from the resonances of the internal volume of the housing, it is filled with a sound absorber, which is mats of technical wool, covered with gauze. The mats are located and secured to internal surfaces body walls.
Electrical filters are mounted inside the housing on one board, providing electrical separation of low-, mid- and high-frequency speaker bands. Electric filters of all modifications of speakers have the same design and fundamental electrical diagrams.
Crossover frequencies provided by filters: between low- and mid-frequency heads - 750±50 Hz, between mid- and high-frequency heads - 5000±500 Hz.
The design of the filters and the overload indication unit uses resistors such as BC, MLT, SPZ-38B, S5-35V, PPB, capacitors such as MBGO-2, K50-I2, K75-11 and inductors on plastic cast frames.
The removable decorative frame included in the “S-90”, “S-90D” kits is covered with knitted fabric with high acoustic transparency.
The delivery set includes four plastic feet, which can be attached to the base of the case if necessary.

Filter circuits

Schemes S-90 - 35AC-012

Scheme S-90 - 35AC-212

Scheme S-90 - 35AC-1 (35AC-201)

When both level switches S1 and S2 are in the position shown in the diagram (“max”), the signal is supplied to the mid-frequency head BA2 through the sound pressure equalizing resistor R3, and to the high-frequency head V3 directly. When the SI switch is moved to the middle (“normal”) or second extreme position “min.” various voltage dividers are included in the circuit of head B2, as a result of which the average sound pressure created by the loudspeaker in the frequency range of 500 Hz.. 5 kHz is reduced by 3 or 6 dB, respectively. When switch S2 is set to the middle or second extreme position, voltage dividers are included in the circuit VZ heads. which leads to the same decreases in average sound pressure at frequencies above 5 kHz.
The voltage dividers use resistors MON (R2, R5) and PEV (the rest).

Schemes S-90B, S-90D, S-90F S-100B, S-100D, S-100F

Appearance of Filter S-90B

Reworking the S-90 filter

Having been an opponent of audiophilia as a simplification, after experiments I changed my point of view and now I’m even ready to sacrifice something for the sake of a small number of obstacles in the path of sound :). This is actually very important, even on the speakers discussed below. But this also forces you to sacrifice some things: high power and congestion of frequency bands.

I used the crossover below, broken down into pieces, for my s-90de with speakers: 30GD-2, 6GDSH-5-5, 3GD-2, where it plays simply wonderful with any genre of music. 3GD-2 (its worse analogue 6GDV-1-16) is a very old high-frequency speaker (my copy is from 1977) with a resonance frequency of as much as 4500 Hz (but there is an opinion that in this place it is quite calm), therefore the high frequency of the midrange section is HF is due precisely to this fact. However, most domestic tweeters have not gone far, so I consider this cut to be very good for them.

This filter will work great on good foreign mid-high-frequency speakers, which I tried myself :). But, of course, it needs to be changed taking into account everything new (including the frequency of the section) - taking the principle itself as a basis.

p.s. Still, we should not forget that everything in the world is not only relative, but also subjective :). In addition, at the moment I have absolutely no means of measuring the frequency response of my system - everything is adjusted by ear in the same room...

speakers

NC: Let's look at the generally good bass driver used in the s-90. 30GD-2 (75GDN-1-4) with a nominal resistance Z=4Ohm, sensitivity S=86dB (or dB/W*m) and frequencies F=30-1000Hz does not provide the best IFC (impedance-frequency characteristic:)) in the compartment with poor sound at frequencies above 500Hz.

Our cutoff will be at 500Hz. Ideally, to make this speaker work really well, you would cut off everything above 200Hz. After all, the main drawback of the 30GD-2 is that at these frequencies it mumbles (“sound from under the diffuser hood”) and plays very poorly. But to make such a low crossover frequency you need an excellent midrange speaker with a resonance frequency of no more than 70Hz.

MF: The standard mid-range driver 15GD-11 (20GDS-4-8), with parameters Z=8Ohm, S=89dB, F=200-5000Hz, does not stand up to any criticism either in terms of sound or the characteristics we need. Therefore, it needs to be replaced with the nice baby 6GDSh-5-4 (Z=4Ohm, S=92dB, F=150-12000Hz) which looks completely frivolous, but in fact turns out to be very good. In addition, it has the sizes we need, price (no more than $4!) and availability in Russia.
It should be noted the low power of the 6GDSH-5 (as a result, the inability to work at discos/parties) and bursts in some parts of the frequency range (“loudness”).

There were opinions that the 6GDSH-5 has poor directivity at high frequencies, which is why the stereo panorama is “unstable” at a relatively high section. It seemed to me that this was not so, so if there are problems, act according to the circumstances :).

HF: Any tweeter with parameters S=89-92dB and Z=16Ohm will do. It is important to note F (actually, the minimum operating frequency of the speaker) - it should not be more than 4500Hz, and the lower the better.
Structural dimensions and fastenings are selected on site using available means.

sensitivity

MF: To cut off the extra 7 dB (92-85 = 6), I suggest using the option of one resistor, which will avoid unnecessary elements in the circuit and at the same time reduce the ratings of the filter elements due to an increase in the speaker resistance. Resistor R2=4.3Ohm will give us a reduction of 6dB. The sensitivity is reduced by a resistor in the approximate ratio of 1 dB/0.7 Ohm. Coil L1 has its own resistance of 0.75 Ohm and will help us remove another 1 dB. Voila! :)

However, the disadvantage here is that there are no exact formulas and dependencies, and the values ​​I gave appeared as a result of my personal feelings.

HF: We use the same method, selecting the desired resistor until the desired result is achieved. However, in this circuit there are no filter elements with a high intrinsic resistance, so resistor R1 must be taken with a margin of 1 dB. We also note that the volume of the high-frequency speakers relative to others in the system strongly characterizes its “inclinations” - for example, most listeners like a slightly muffled high-frequency sound (by about 1-2 dB), the system seems to be “softer”. What is relevant for domestic high-frequency speakers is not the most best quality:)). For heavy music, emphasizing the high frequencies may be more important.

It's nice to know that changing the sensitivity resistors within one unit (1 Ohm) has virtually no effect on the filter itself and the cutoff frequencies, which makes it possible to experiment.

But you shouldn't cross the 0.7 Ohm difference when experimenting with R2 - the L1 coil is much more sensitive to this change.

inductors

The most difficult thing. We urgently need to find ways to measure inductance, otherwise precise tuning will not work.

In the absence of a way to measure, I suggest the following: compare the coils by their own resistance, taking into account all design parameters. Theoretically, if all the factors influencing the inductance rating coincide (there are some very interesting ones - the density of turns, the content of iron impurities in the frame :)), then you can obtain the necessary inductance, as if “following a model”.

Despite everything, this method, it must be said, is very inaccurate. There is no difference between the inductance L2, for example, 1.5 mH and 1.27 mH in terms of resistance.

LF: I’ll give my parameters for a large coil (it also has “ears” on the sides): inner diameter of the ring: 35mm, outer: 70mm, coil height: 37mm, width of the winding area (height without sides): 30mm, wire thickness (copper, enameled ): 1mm. With these parameters, the coil resistance DC(measured by digital tester): 0.8 Ohm.
If these parameters are observed, you should get an inductance in the region of 1.0-1.6 mH, congratulations :).

You can wind the coil the “old fashioned” way, knowing how many turns you need to make. This has recently become known: for 1.27 mH, 210 turns of “manual” (not very neat) winding are required. In this case, for every 0.05 mH there are approximately 5 turns.

SC: The small coils should all be the same in frame; I took the one with the smallest inductance. Inner ring diameter: 12mm, outer: 32mm, coil height: 23mm, winding area width (height without edges): 18mm, wire thickness (copper, enameled): 0.5mm. Resistance: 0.7 Ohm, inductance 0.18-0.21 mH.

At 0.18 mH the number of turns is 127 pieces. At 0.21 mH - 136.

By the way, do not repeat the mistakes of the USSR assemblers, do not fasten small coils with screws inside - the inductance will change and nonlinearity will be added; attach with glue.

For those who measure themselves: it is useless to try to rewind a small coil with a thick wire from a large one, and you probably want to do this :). Even having completely wound the entire frame, I did not get an inductance of more than 0.1 mH.

At the same time, if you build a new optimal frame (see links, “Cec”), which is not as simple as it seems, then the coil’s own resistance will allow you to gain 1 dB to the speaker sensitivity - you will need to slightly calibrate the sensitivity resistors in front of the speakers.

If you try to find the same large frames somewhere else and wind the L1 coils with thick wire, then their resistance will be approximately 0.4 Ohm - also better.

p.s. I kindly ask you not to write me letters asking for help in calculating inductance on other frames and other values ​​using this method. Assemble the “box” (see links), it is very easy and will solve all your problems with precise winding of coils.

capacitors

Everything is extremely simple. You need to find the same values ​​for decent quality capacitors, you can read about the types here, and about resistors there, by the way. Capacitors can be combined (summed) in parallel (as well as reduced according to the resistance rule by connecting in series). If you have disassembled the s-90 filters, then you should already have a good set of necessary containers :).

Among the domestic ones, instead of the film K73-xx that you probably came across, I recommend trying the metal-paper MBxx - a “softer” sound. If you have the funds and availability, it is advisable to use foreign MKP (1uF ~ $1.1, domestic equivalent - k78).

The capacitors, of course, are non-polar and for a voltage of at least 40V. The quality of the elements in Zobel circuits is just as important.

Here you can experiment with changing the “color” of the system that the capacitors give. I recommend trying to bypass all capacitors (except those in the Zobel circuit) with small (around 0.1 µF) capacitors of other, usually higher quality, types. For example, polystyrene (k71-7) or mica (SGM) - the result is more detailed sound at mid-high frequencies and increases the transparency of the system. In addition, metal-paper (MBxx) capacitors give a slightly “muddy” sound. To bypass means to combine together in parallel :).

resistors

With a power of at least 2W, with less, overheating and a change in rating are possible. Among the domestic ones, MLT-2 can be used. PEV-10 from the s-90 kit are not the best, but they will reluctantly go... I recommend Chinese ceramics - they look like white teeth, they are large, they are inexpensively sold everywhere in radio stores (power up to 15 W), but the range of ratings is fully present.

In other matters, low-power MLT resistors also work well at non-disco power levels, at least in place of R1.

Please note that the value written on the resistor is not necessarily the same as what it actually is. I strongly recommend selecting resistors by measuring them with an ohmmeter/tester. The diagram shows clearly measured resistors.

When finalizing the speakers, it is highly recommended to place resistors R1 and R2 as close to the speakers as possible - directly on the terminals. This will greatly reduce the influence of the cable (which is after these resistors, but not before them) on the sound.
Zobel chains

The reason is that the impedance of the speaker is not constant and increases as the frequency response decreases. This effect occurs in all dynamic type heads without exception, regardless of the country and year of production. More precisely, the Zobel circuit (in my filter only a simplified version of it is used; full ones allow you to adjust the impedance at low frequencies, which is not always necessary) is necessary for the normal operation of the filter inductors, with a sufficiently large self-inductance of the speaker coil. Without a Zobel circuit, the operation of the inductor as a low-pass filter is grossly disrupted and filtering is practically not carried out at all (!).

LF: Elements R4 and C4. It is advisable to set C3 to more than 60 µF, but even this is sufficient for a crossover frequency of 500 Hz. R4 is equal to 4.3 Ohm.

Compare the ICHH of 30GD-2 without and with Zobel. The graphs are approximate, but there you can see the tuning frequency of the s-90 bass reflex - the second huge rock on the left, before 100Hz :).

SC: ICHH 6gdsh-5. You can try smoothing above 3 kHz with Zobel R3, C3. For this, 10-20 µF and an 8.0 Ohm resistor are enough.

Important: a Zobel circuit on the midrange is required for the normal operation of this crossover. Without her" new lightweight filter" showed its complete failure in the midrange and high frequencies.

HF: Due to the low inductance of the speaker's own coil and the cutoff at low frequencies, the circuit is irrelevant.

filter

In all frequency sections, a passive all-pass filter of the first order is used with an attenuation of 6 dB per octave (frequency change by a factor of two), Butterworth approximation. Actually, the filter itself was calculated by the JBL Speaker Shop program and slightly adjusted manually :)).

LF: Low pass filter. As you can already understand, the cutoff frequency is 500 Hz (for 30GD-2/75GDN-1-4, lower is desirable, but was chosen as a compromise to 6GDSH-5). Provided by element L2, speaker load, coupled with a simplified Zobel correction circuit.

Midrange: Bandpass filter. The lower part (C2) is matched with the low-pass filter and is tuned to a cutoff frequency of 500 Hz based on considerations of the resonant frequency of the 6GDSh-5. The upper part (L1) is matched with the high-pass filter and is tuned to 7500Hz, which allows for a broadband speaker structure, coupled with Zobel.
Both parts are loaded at 8 ohms (4 ohms from 6GDSH-5-4 + 4 ohms from R2).

HF: High pass filter. The frequency is matched to the upper part of the midrange filter and operates at 7500Hz, which avoids problems associated with the high frequency of the main resonance of domestic high-frequency speakers. Load 21 Ohm (16 Ohm speaker + 5 Ohm from R1).

All speakers are switched on in phase, which has a lesser effect on the phase characteristics of the system.

scheme

Electrical circuit diagram. Click to enlarge :).

The arrow on the right shows the “sound input” from the amplifier. The dotted lines are bi-wiring (the low-pass and mid-high-frequency sections of the filter are connected to each other in parallel at the amplifier - plus the low-pass with the plus of the mid-range and high-frequency to the plus of the amplifier, the minuses are the same).

The gray numbers in brackets above the filter elements indicate their load. The gray numbers with an "r" in front of them are the element's own resistance. Gray marks -1dB - loss of speaker sensitivity on the elements.

Next to the speakers, their important characteristics are briefly written out; below are the frequencies at which the bands/links intersect.

Inductance in mH, capacitance in µF, resistance in Ohm. After assembling the filter, the nominal speaker impedance for the amplifier remains equal to 4 Ohms.

A version of the “new lightweight” filter for s-90 clones, more precisely for Orbit 35AC-016. Speakers: 10gdv-2-16, 6gdsh-5-4, 75gdn-1-4 - a fairly common set.