This page contains diagrams of Radiotehnika class S90 speaker systems (35AC-212, S90, S90B, S90D, S90F, S-90E), detailed descriptions, speaker parameters, photographs.

Quite high-quality acoustics from Soviet times, after minor modifications and restoration, I can say with confidence that it will give a head start to many modern acoustic systems.

If you have similar ones lying around or bought them somewhere cheap, then put them in order and they will delight you for a long time with powerful bass, rich mid and high frequencies in musical works of any style and direction, in general I RECOMMEND!!!

Acoustic system S-90 (first model)

Rice. 1. Appearance of Radiotehnika S-90 speakers.

The speaker system has two step playback level controls separately for mid and high frequencies in the ranges from 500 to 5000 Hz and from 5 to 20 kHz, respectively.

Both regulators have three fixed positions: “0”, “-3dB” and “-6 dB”. In position "0", the signal from the crossover filter is supplied to the corresponding head directly. In the “-3 dB” and “-6 dB” positions, the signal is weakened relative to the “0” position by 1.4 and 2 times, respectively.
With the appropriate spectral composition of the program, switching the regulator changes the timbre coloring of the sound.

Passport technical characteristics of S-90:

Rice. 2. Schematic diagram of acoustic speakers S90 35AC-212.

Acoustic system S-90 35AC-1

Rice. 3. Speaker system Radiotekhnika S-90 35AC-1, appearance, photo.

Rice. 4. Schematic diagram of the Radiotehnika S90 35AC-1 speaker.

Speaker system Radiotehnika S-90B

Rice. 5. Appearance of speaker systems Radiotekhnika S-90B.

Speaker system S-90D

Rice. 6. Appearance of acoustic speakers Radiotehnika S-90D.

The speakers have an indication of speaker head overload. The controls located on the front panel of the speaker make it possible to smoothly adjust the sound pressure level of the high-frequency and mid-frequency loudspeaker heads within the range from 0 to minus 6 dB.

There is also a model of the speaker system "S-100D", it uses a mid-frequency head 30 GDS-3 with MAHID magnetic fluid, which allows you to increase the rated power of the speaker system to 100 W. Otherwise, the designs of "S-90D" and "S-100D" are similar.

To operate, the speakers must be connected to an amplifier that has the highest (maximum) power at the output of each channel, ranging from 50 to 150 W.

If the OVERLOAD indicators start to light up when the speaker is operating, then you should reduce the level of the input signal supplied to it (by using the volume control in the amplifier to which the speaker is connected).

S-90D technical specifications:

The picture below shows

Acoustic design

Speaker design features that have a direct impact on sound quality. Possible acoustic design options: bass reflex type, closed type, open type, with a passive radiator, . The body of a closed-type acoustic system is a hermetically sealed box with a speaker diffuser (sound emitter) located on the front panel. 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. Speakers with a bass reflex have a closed housing, on one of the walls or at the bottom of which there is an output hole (or port) of the bass reflex, connecting the internal volume of the speaker system with the outside world. The bass reflex itself is a tube of a certain length, selected so that the sound wave emitted by the rear side of the diffuser is reversed in phase and exits through the port. As a result, sound waves from the rear and front surfaces of the diffuser are added, increasing the sound pressure level of the speaker. The advantages of such acoustics are high sensitivity, reproduction of the deepest bass, and small sizes (compared to similar closed-type speakers). Disadvantages - poor transient response, which manifests itself in practice as a slight “smearing” of the sound. A type of bass reflex type speaker is a speaker with a passive radiator, or “passive radiator”. In design, they resemble speakers with a bass reflex, but instead 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 bass reflex. 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 reflex is the absence of air flow noise in the resonator pipe. Open-type speaker systems are very rare; in them, the housing is a thick panel in which the speakers are installed. Such loudspeakers provide dipole-type acoustic radiation (see “Acoustic radiation”), that is, sound vibrations from the speaker propagate both from the front and from the rear. Due to the fact that such speakers have virtually no housing, all negative vibrations that occur during resonance in speakers with a “regular” housing are minimized. "Open" speakers can be installed close to the wall, since the sound practically does not travel laterally. Open-type speakers have a weakened reproduction of low frequencies, so manufacturers have to install very large woofers (much larger than in closed speakers or speakers with a bass reflex). Bandpass or strip body contains elements of a closed box and a body with a bass reflex. This housing is divided into two parts by a partition. One part is completely closed, and the second has access to the outside in the form of a bass reflex tunnel, through which the bass is supplied outside in a concentrated form. The low-frequency speaker is mounted on the partition. The main advantage of a strip housing is high efficiency. In other words, a speaker installed in a bandpass will sound louder than the same speaker installed in a closed enclosure. In addition, the subwoofer in a bandpass housing produces sound in a narrow low frequency band. Most modern speaker systems use a bass reflex design.

I have long had a dream - to buy the legendary S90 and modify them with a file, in order to make a budget solution that will be the envy of everyone. After monitoring various flea markets for a long time, I finally bought a 35AC-212 “Radio Engineering” S90 from 1981 on one speaker (my peers;)).
The condition on the outside is a solid 4, no one has tampered with the inside with crooked paws. There was only one minus - the bass driver from one speaker was killed, which was honestly reported to me, and I really didn’t like the fact that both woofers were painted silver (it’s good that the paint is not deep paint, i.e. the mass of the diffuser has not increased much).
For 1000 rub. I bought a set for creativity.
We will improve it.
Oh, I feel strong polemics between supporters of improvements to Soviet acoustics and supporters of burying it completely and without turning.
I immediately apologize for the quality of the photos, because at the time of revision, and even now I do not have a digital camera other than a phone.

Let's climb inside

After listening, I decided to disassemble each speaker to see if the insides matched the speakers' passports. As it turned out, the HF quality is 10GD-35, MF 15GD-11A, and LF 35GD (something) I don’t remember, but with a rubber suspension that hasn’t dried out.
The first thing I did was rewind the woofer.
Restoring the speaker was no problem for me, since I did this very often in my youth for little money. Unfortunately, I didn’t have a mandrel of a suitable diameter, but I have a need for invention and I went to the nearest construction store with a caliper in my pocket. As a mandrel, I bought some kind of plumbing pipe for what seemed like 20 rubles. I sawed it lengthwise (this is necessary since after winding it would be practically impossible to remove the coil from the mandrel).
Let's add another 20 minutes for winding and centering and a day to dry the speaker. That's it, the speaker started playing without any extraneous sounds and as if untouched.

Let's start with the tweeters

After listening to the result and reading the great Internet, I began to think further about how to make the sound even better. Basically, all types of modifications come down to replacing the HF, replacing the midrange and damping the body.
The highs really don't sound very good. There are unpleasant overtones in the high frequencies and a lack of ringing in the midrange. The HF section uses speakers with domes made of some kind of plastic/polyethylene. For comparison, I installed 10 W speakers with silk domes, the high-frequency sound became much more transparent and the overtones that simply grated the ear disappeared. As a result, these rootless speakers for about 500 rubles per pair remained in them. I bought them a long time ago and the markings on them are unreadable, and I don’t remember what was written on the price tag. You can also use 10GDV speakers with silk domes.

I note that I first made one speaker and compared the sound from the test discs with the sound of the original speaker. After listening, I decide to leave the rework or return everything back. Everything was done according to my favorite ear, which never seemed to let me down.

Refinement of the body

Next I decided to do low frequencies, i.e. modification of the body. Batting was bought for ridiculous money - 38 rubles per meter of length and 2-something meters wide. Having also looked at the manufactured filters, I heeded the advice to change all the wiring in the speakers.
I removed all the speakers from the speakers. I took out the filter and switches. The wires can be safely cut since they will need to be replaced anyway.
Next, I cut out the required piece of batting, borrowed a furniture stapler from a friend, and began sheathing them inside in 2 layers.

We put the bass reflex pipe on the sealant and also cover it with batting.

The next thing you need to do is modify the filter.

The filter circuit is simple

I turned off the switches completely, since they are completely unnecessary. We remove unnecessary elements from the filter board.
We replace all the thin conductors in the filter with normal copper wire.
Here is the filter before modification.

And this is a copper wire about 4 squares used for almost all connections

As a result, rebuilt with removed dividers and regulators


Next we install it in the body and cover it with batting.
We also cover the entire midrange box from the outside with batting.

midrange link

In principle, after such modifications, the sound changed for the better, the bass became clearer, the upper frequencies became “more transparent” and “lighter”, but I still didn’t like the mids, the upper mids were not enough. There was not enough ringing in the vocals.
After rummaging through my supplies I found two 4GD-8Es in excellent condition. I installed one speaker and spent a long time comparing the results. I liked the result. In one blues recording I heard brushes hitting the main drum. Before that I didn't distinguish them.
But these speakers did not last long in acoustics.
After listening to the modified speakers for a week, I came to the conclusion that the sound began to tire me.
Probably all this is caused by the fact that the 4GD-8E dynamic heads have a very high quality factor and, in a closed box, have a very jagged frequency response. Unfortunately, there is no normal microphone to take measurements. Yes, the midrange speakers were equipped with a foam pad covering the rear holes in the speakers. The midrange box itself is filled with fluffy “eye” cotton.

On the Internet they often wrote about 5GDSH-5-4 and 6-GDSH-5, about the fact that after installing the PAS they produce excellent midrange frequencies. Walking through neighboring radio stores, I bought a pair of 6-GDSH-5 4 Ohms for 110 rubles. As far as I understand, they are installed in household electronic equipment. I sealed the windows in the diffuser holder basket with thin batting and installed them instead of 15GD-11A, fortunately their installation dimensions are completely the same. There is another way to refine the midrange speakers - impregnating the suspension with mystical guerlain mixed with the blood of the orchestra conductor with acetone and applying a thin layer to the back side of the diffuser. But as far as I understand, this is quite rare and in construction stores they just shrug their shoulders. It would be worth taking for an experiment, because 110 rubles for a pair of new speakers is not a pity.

After all operations, we completely assemble the acoustics and enjoy the new sound. I tested the sound on Sukhoi’s homemade high-fidelity amplifier (I’m afraid that true Hi-Fi connoisseurs will spew rays of diarrhea in my direction). By the way, I also assembled the amplifier myself, with minor modifications to the power supply, and it has been playing for exactly more than a decade, but that’s how it works in the same form as an engineering sample. I connected it all to Sb Live! Playing flac of special discs such as audio doctor. And just wav and flac discs that are specifically recommended for testing the audio path.

Bottom line

Costs 1000 rub. the acoustics themselves
500 RUR HF speakers
110 RUR Midrange speakers
RUB 150 batting, glue, staples, screws and other small items
Total 1760 rub.
What did we get?

Such nice acoustics

What follows is only my opinion and the opinion of my friends who have experienced it.
A friend who owns jbl floorstanding speakers, I don’t remember the model, but they cost about 20,000 for one and a Yamaha receiver, he definitely agreed that after the S90 modifications, his set is being replayed.
I'm completely satisfied with the sound. Walking around different salons with acoustics and listening to them, I understand that such sound is cheaper than 15,000 rubles. You can't buy one speaker.

PS Now they are playing together with Gumel's Simple amplifier and Sukhoi's BB pre-amplifier. Everything is connected to the same sound system SB Live! and works as a front to 4.0 sound for watching movies on a 37" LCD panel. There is more than enough realism in disaster films. I don’t even think about adding a subwoofer.

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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 vastness 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 the 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 widespread; 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 listening to music; we all have a good mood when we 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 buzzing, 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 this 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 decorate it with the root 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 the question of replacing the housing, which arises in full force.

The task is somewhat complicated by the fact that over 30 years a huge number of modifications of the 35AC-1 speakers with 30GD2/75GDN1-4 (8) low-frequency speakers have been released, which have a wide range of parameters. In the 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.

What these speakers have that can be fundamentally improved 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 response and poor bass quality;
• The “bass reflex” type of low-frequency design in combination with a “tight” speaker on a rubber surround leads to an extended and monotonous “hum” at low frequencies, instead of a clear striking 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 turn 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.

Music lovers constantly start debates about which speaker system to choose for comfortable listening to music at home. And this is no accident: the entire contingent was divided into two camps. The first believe that it is worth shelling out a tidy sum to buy a cool Hi-Fi (or better yet, Hi-End) system in order to be happy and forget about headaches about this topic for the rest of your life. But there are also those who are not ready to give up their entire life’s savings for expensive acoustics (instead of the required car or apartment), and therefore consider the best option to purchase simpler equipment or improve the good old classics to good sound.

In this article we will talk about one of the most popular audio systems produced during the USSR, which could not leave any of its owners indifferent. The S90 speakers, the technical characteristics of which can excite consciousness to this day, have become one of the highest achievements of the Soviet company Radiotekhnika.

Speaker models

The very first thing worth mentioning is the real and full name of the speaker model - 35AC-012. An important factor is that this acoustics was produced in several variations. The most popular of them are S90 and S90B. There were also S90i, S90D and S90f models, but they were not widely used and are now almost unheard of.

The model with the postfix “B” differed from the usual “nineties” in a wider range of reproduced frequencies. Another significant difference was the introduction of an electrical overload indicator for the speakers. The recommended power of a high-quality amplifier for these speakers is in the range from 20 to 90 watts. It is also worth noting that Radiotekhnika S90, S90B (and other modifications) were the first models of speaker systems that met international requirements for Hi-Fi equipment.

Design

The case in which the S90 speakers are enclosed is, in fact, a non-demountable rectangular box made of veneered wood made of precious wood. The thickness of the speaker walls reaches 16 mm, the front panel is made of plywood 22 mm thick. The internal joints of the cabinet walls are connected by special elements that increase the rigidity and strength of the structure, but do not interfere with high-quality sound.

If you look at the device from the front, the speakers are arranged in the following order (from top to bottom): tweeter, midrange speaker and woofer. Also on the front panel of the S90 speaker you can see the frequency response (amplitude-frequency response) graph and the bass reflex hole. While the frequency response is located at the top or bottom (depending on the acoustic model), the bass reflex is always located at the bottom. This was done for reasons of proper design for better sound and giving the speakers good bass.

Speakers S90: characteristics

If we take the regular S90 as an example, they have dynamic direct radiation heads installed. More precisely, a high-frequency head 10GD-35, a mid-frequency head 15GD-11A and a low-frequency head 30GD-2 (in later models - 75GDN-1-4).

Equipped with two step playback level controls to adjust the midrange and treble in the ranges from 500 to 5000 Hz and from 5 to 20 kHz. Each regulator moves in three fixed positions. In position “0” there is no obstacle for the signal from the crossover filter, and it is fed directly to the corresponding head. When using the “-3 dB” and “-6 dB” positions, the signal is attenuated by 1.4 and 2 times, respectively, relative to the “0” position. By switching the selected control, you can change the timbre of the sound.

The rated power of the S90 speakers is 90 Watts, while the nominal power is 35 Watts. The nominal electrical resistance of this speaker system is 4 ohms, and the range of frequencies available for playback ranges from 31.5 Hz to 20 kHz. The nominal sound pressure of the S90 is 1.2 Pa. I would like to note the rather impressive dimensions of one column - 71.0 x 36.0 x 28.5 cm, and the total weight of the entire system reaches 30 kg.

Speaker circuit and connection to the sound source

In order to understand whether it is worthwhile to modify any speaker system, you need to study all the data and aspects of the equipment. Below is the electrical diagram of the S90 speakers. Anyone, even a novice radio amateur, can understand it; you just need to have at least basic knowledge.

Another important point is the correct connection of the speaker system. After all, if something goes wrong, even during connection you can, without meaning to, damage the equipment. You don't need to be a professional to figure out how to connect S90 speakers. The main thing is to have at least 20 watts with the amplifier (in this case, most likely, the sound will not be loud enough for large rooms), but not more than 90 watts. If the amplifier's permissible power value is exceeded, the user risks being left without acoustics due to its breakdown. To connect, you will need regular speaker wires, which must be connected to the terminals on each speaker and amplifier. The main condition for connection is compliance with polarity.

Revision 35AS-012

As it becomes clear from the description above, it itself has good technical characteristics and is capable of “rocking up” even small public spaces. But for home use, the most sophisticated music lover will prefer to modify the S90 speakers with his own hands. And all because the acoustic systems of the Radiotekhnika company, assembled more than twenty (or even thirty) years ago, did not already have high build quality and the materials used in those years.

Analysis

In the event that the acoustics were purchased in used condition and are currently well-worn by life, it is worth paying attention to the appearance. To do this, you need to disassemble the S90 speakers, first placing them on their “back”.

When removing the speakers, you need to take into account that the tweeter and midrange heads are attached to the housing using the same screws as the covers. The woofer is attached separately, and you need to be as careful as possible not to damage it when unscrewing it.

The HF/MF controls are much easier to dismantle than they seem. All you need to do is carefully remove the decorative plugs that are located in the center of each regulator. After this, using a screwdriver, you need to unscrew the screw that is revealed to the eye and remove the regulator handle itself. The plastic lining must be carefully lifted on both sides using flat objects and removed, and the four screws remaining under it must be unscrewed. Then you can push the S90 inside the speaker, not forgetting to unsolder it from the filter.

The cotton wool bags located inside the case must be removed. Again, if the previous owner of the speakers did not forget to return them to their place in case of disassembly.

You should first unsolder the panel with filters from the output on the rear side of the speaker, and then you need to dismantle it by unscrewing the screws. Now you can remove the panel with the terminals attached to it.

Appearance and body

If the grilles and decorative covers of the speakers are “tired,” then it is worth straightening them and painting them, having previously sanded and degreased them. This will give the speakers a fresh look. The body of the S90 speaker becomes loose over time and can be strengthened if desired. This will result in a better sounding woofer.

This can be done in various ways, including installing spacers and additional corners inside. It is also necessary to pay attention to sealing all joints and seams using conventional plumbing sealant. In addition, you can glue the inner walls of the case with foam rubber (except for the front), which will increase the volume of the latter.

Terminals and filter

Knowledgeable radio amateurs advise replacing the standard speaker terminals with universal type terminals with gold-plated connectors. The installation location must be lubricated with sealant and the panel with terminals must be put in place.

Considerable attention should be paid to the sound filter. If it was attached to the body with metal screws, then the filter settings will be lost. There are cases where the filter was assembled on a metal plate. This can be corrected by transferring all nodes to a plywood panel. The circuit of the filter itself may have been changed at the manufacturer due to different parameters of the speakers, so you should make sure that everything is assembled in accordance with GOST. If there are jumpers in the filter, then they must be removed and replaced, for example, with an oxygen-free copper cable with a cross-sectional area of ​​4 mm 2. It is worth removing the attenuator from the circuit, as it simply distorts the sound, and replacing the wires used to connect the speakers to the filter.

For low-frequency speakers, a wire with a cross-section of 4 mm 2 is suitable, for mid-range speakers - with an area of ​​2.5 mm 2, for high-frequency speakers - with an area of ​​2 mm 2. After these simple steps, the filter must be returned to its place and covered with foam rubber.

Speakers and other "trifles"

New seals should be cut for the speakers. This can be done using cheap or simply outdated computer mouse pads. This is the simplest option. After this, it is worth returning them to their seats and installing decorative overlays and nets.

Before installing the regulators in place, you will have to remove all resistance from them. When installing them in place, it is imperative to use sealant, as when installing a bass reflex.

Through such simple manipulations, the S90 speakers acquire new life. The sound quality becomes an order of magnitude higher, despite the low costs. As a result, we can say that if you don’t have the money for expensive 2.0 format acoustics, you can use a similar option and become the happy owner of the time-tested Radiotekhnika S90 speaker. If it happens that only half of the speakers are available, do not be upset. After all, it is remarkable that the S90 speaker, a photo of which can be found on almost any site for acoustics lovers from the times of the USSR, can work alone and give good results.