Restoring speakers Radiotekhnika S30. Refinement of the S90 or how to make them “sing” at minimal cost. There are speakers from the s90, make the speakers yourself

Who doesn’t remember the famous S-90 speakers from the 70s? (In fact, there was a Latin letter S, and therefore this Riga product was called the Radiotehnika S-90 speaker system, but the habit of not trusting anything 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 the 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 an ordinary apartment of a 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 proper installation, which was not always combined with the capabilities.

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 the ideal way for better sound is to 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 with special elements that increase 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 the bottom rear wall 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, low frequencies become inaudible and booming, and the highs begin to clatter - this is a characteristic feature of the 6GDV-1-16 high-frequency drivers. 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 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.

I somehow got Soviet S-30 speakers. Their condition was deplorable: their speakers did not work (the wiring had broken due to age). Later I made them, temporarily hooking them up with small wires.

They worked for me for 2-3 weeks as part of the house. cinema, and one fine day I was inspired to remake them (“modding”).

Main technical characteristics of Radio Engineering S30:

What we need: Soldering iron, straight hands, rosin, solder, glue, black “screws”, wires, a lot of free time, a car (bicycle) tube, a plastic pipe, that’s all.

First, let's take everything completely apart:

First I changed the wires from the filter to the speakers:

BEFORE (agree, these wires are worse):

After (sounding better with them):

Have you laid the wires? Now you need to glue the speaker body with any glue so that there are no gaps, I used “silicone”.
I placed the camera on the viscous mass (cut out the appropriate dimensions) and pressed it firmly (this way the camera will “stick” to the speaker body)

Now it’s time for the filters, I changed the wires on them.

under development:

A few words about the filter:
If we want: we turn off the overload indication unit (if the amplifier is not more powerful than 25-30 W - otherwise then we listen with caution) - according to the diagram, we cut the track from the input (red wire +) to VD KA522B (see diagram) and unsolder the capacitor C2 10 μF and the transistor VT2 KT315b .

We disconnect the plug connector and solder the wires going to the speakers, throw out the old ones! In their place we put audio wires with a cross-section of at least 2.5 mm 2, directly to the board, on the back side of the connector. From the woofer speaker “+” to connector No. 2 and “-” to connector No. 3. “Tweeter” (HF), respectively, “+” to No. 5 and “-” to No. 2 (this is necessary - it is in antiphase).

Here is the filter diagram.

If you disable some elements (that you do not need)

You can experiment carefully: add anti-magnets of the required size to the 10GD34 and reduce the coefficient of the resistive divider on the HF using a substring resistor, having previously marked the original position with a subtracting resistor so that you can return to the original state of the filters. All this will increase the mid-high frequency output and the overall dynamic range. The anti-magnets in one pair are glued slightly different - I selected them to equalize the output of both speakers in the midrange.

Rated power... 35 W

Nominal electrical resistance... 4 Ohm

Frequency range... 31.5-20000 Hz

Nominal sound pressure... 1.2 Pa

Overall dimensions of the speaker... 360x710x285 mm

Speaker weight no more than... 30 kg

S-90 is a classic of Soviet column construction. According to the manual, the S-90 speaker system is designed for high-quality reproduction of sound programs in combination with various types of household radio equipment.

Well, for the early 80s these were truly outstanding speakers with high sound quality. However, foreign speaker construction is developing, and already at the beginning of the new century, the sound of the S-90 is perceived differently.

High frequencies sound disgusting, there is simply NO midrange! And if we talk about bass, then a similar effect will be when placing a healthy bass player in a large kick drum... The lows drone on in black. It is impossible to listen to D&B style music; IDM also hits the ears. What can we say about classics and calm music. After an hour or two of listening, my ears begin to hurt (however, my head and stomach hurt no less). Despite these shortcomings, many people buy these speakers.

All of the following applies to Radiotechnika S-90a (AC35-212) speakers. This is one of the very first releases (and one of the best), characteristic features - 2 controls on the front panel, HF and midrange speakers shifted from the center, paired speakers, 4 Ohm impedance. However, the meaning of the modification and the modification itself can easily be applied to other S-90 (S-90b, S-90F, etc.), their analogues (Orbit, Amphiton, etc.), as well as to homemade speakers . The main criterion is the presence of 3 bands (speakers) and a bass reflex. The modification of speakers with a closed cabinet (i.e. without a bass reflex) is somewhat different, I will write about this later. And one more thing - there are many options for improvement, so in some places I will describe 2 methods. You will choose the most suitable one yourself..
I won’t write a list of necessary materials - in most cases, everyone uses what is most available at the moment.

1) Disassembly

We take one speaker and place it on the floor with its back wall (this is the most convenient way to remove the speakers). Using a figured screwdriver, unscrew the 6 bolts securing the decorative plastic trim from the bottom of the column. Using a flat-head screwdriver, unscrew 4 bolts and remove the decorative nameplates from the speakers and the protective grilles.

Next, you will need a heated soldering iron! Then we unscrew the 4 bolts securing the woofer and carefully lift one side of it and remove it from the housing. We unsolder the wires (you can, of course, mark which one was soldered where - but it’s better to then check the diagram and solder it 100% correctly) and put it aside. We remove the midrange speaker from the housing (it was secured with a nameplate) along with the glass in which it stands. Unsolder it and put it to the woofer. We take out the HF (tweeter) - it was also attached with a nameplate and unsolder it. If there is no mark on it at one of the terminals (+), we mark which wire was soldered where, then we look where it goes according to the diagram and find “+”. We put it with the other speakers.

Be careful with diffusers! The speakers can only be grasped by the magnet or diffuser holder supports!!!
Unscrew the 4 screws on the bass reflex and carefully remove it from the housing. It is held on by sealant, the main thing here is not to use excessive force - it may break! We take out 2 “sausages” of cotton wool from the body (if it is there). We unscrew and remove the filter from the housing (it can be either on an iron chassis or on a wooden plank). The wires going to it can be cut off with wire cutters (they still need to be replaced early). That's all with disassembly! Now we need to finalize and assemble.

2) Modification of the case - it is advisable to strengthen the back side of the case with wooden slats (attached with screws and epoxy). It is also necessary to place a wooden spacer in the center of the speaker (between the rear wall and the front) at the level of the midrange glass. (the main thing is to pay attention to the possibility of then installing a bass reflex!!!) This is necessary to reduce vibrations of the body - turn it up louder and put your hand on it - the body shakes! You also need to check the tightness of the housing at the joints and, if necessary, coat the joints with epoxy glue or sealant.

3) Refinement of the filter: You will need a diagram.

The point is to remove switches from the circuit, replace the wires with audio made of oxygen-free copper, solder the speakers directly to the filter, solder the lead wire directly to the filter and shorten the signal path

In the absence of finances, you can also supply suitable copper ones from the Soviet Union. The point of selecting wires is to have a multi-core wire for the woofer, the larger the better (but not less than 2.5 mm2, and it’s bad to solder more than 4 mm2), for the midrange you can have a multi-core of at least 1.5 mm2, and for the high frequency - a single-core of at least 1 mm2 (I recommend using a core from a twisted pair cable of the fifth category for + and -). It should be said that the selection of wires is a delicate matter. There are still fierce discussions about the choice of wire for speakers. I express my personal opinion. I advise you not to skimp and buy at least the cheapest audio cable! The sound quality greatly depends on it! Take my word for it.

I also highly recommend remounting all the filter parts on a small piece of plywood/wood, so that you can place the filter on the bottom of the speaker, next to the bass reflex. This is important (especially if the filter is mounted on an iron plate). The inductors should be attached to the new board not with iron screws, but with something plastic or mounted on epoxy. So, we replace all the wires on the filter board - we install it directly to the outputs of the capacitors, removing the contact plates from them.

I will not give the sequence for replacing the wires. As well as tips on where to solder the wires from the bass, midrange and treble. I hope you figure it out :). If you can’t cope, invite a knowledgeable person (one who can distinguish a capacitor from a resistor will do). As a last resort, write to me by e-mail [email protected]. We're done with the filter - put it aside.

4) Hull damping:

The point is to, if possible, absorb and dissipate all standing waves inside the housing. The criterion for choosing a material is that the denser and thicker it is (felt), the better it absorbs; the thinner and lighter it is (synthetic winterizer), the worse it is. The best way to make a pancake is to coat the body with sound-absorbing mastic (automotive mastic will do), then glue a layer of felt under 1 cm + the low-frequency part with another such layer and stick chaotically pieces of felt on top. They also recommend covering it with a layer of material for kitchen hoods - I don’t know, I haven’t seen it. I did this myself - everything is upholstered with 1.5 cm felt + the bottom part is another 1.5 cm + pieces. The sound absorber must be glued throughout the entire inside of the housing. After installing the first layer of felt, I recommend placing a filter board (with wires soldered to it) and a bass reflex port on the bottom of the speaker (otherwise you won’t be able to put it in later!), placing the remaining layers of sound absorber while closing the filter. and also wrap the bass reflex with a sound absorber (the main thing is not to cover the internal section of the pipe and maintain direct access from the bass diffuser to the bass reflex). It is necessary to look at the internal volume of the case - you cannot reduce it excessively - it will affect the depth of the bass! The body is finished.

By the way, I advise those who want to find household felt, about 1.5 cm thick.

5) Midrange speaker and its glass.

I highly recommend replacing the standard 15GD-11A (or its clone) with a broadband 6-GDSH-5-4 or 6-GDSH-5-8. The difference between them is that the first has a resistance of 4 ohms, and the second has 8 ohms. Accordingly, when installing 6-GDSH-5-8, the filter does not need to be changed, and when installing 6-GDSH-5-4, put a 4 Ohm large resistor (6-10 W) power. Resistor R3 (4.3 Ohm) from the midrange divider (columns 35AC212) is just suitable for this. Don't worry about losing power with this swap! You will only benefit in sound quality. The method has already been tested on many S-90s, there are no negative reviews, the power has not decreased. Moreover, competitors for the 6-GDSh-5 still need to be looked for (even among foreign analogues). And this is when the cost of a pair of these broadband speakers (new!) is $4-6. They have only one minus - appearance. Although I like it :).

For the midrange you need to make a PAS. This means covering the windows of the diffuser holder on the back of the speaker with a layer of foam rubber 0.5-0.8 cm thick. Quilted batting will also work. It is convenient to cut a strip of foam rubber 4-5 cm wide and a length equal to slightly less than the perimeter of the speaker, sew it and stretch it over the windows (for 15GD-11A). Then sew with threads to the supports. We made a PAS (be sure to do it - it degrades the quality factor, which is vital for almost all Soviet midranges used in the S-90 15GD11, and even more so!) - you can install the glass and speaker in place. Insert the glass into the body and wrap the outside in 2-3 layers of a good, dense sound absorber. It is convenient to cut off a boot boot that is suitable in height and width from a felt boot, place it in the body, and then place a glass of midrange in it. The inside of the glass also needs to be covered with a layer of sound absorber (felt is just right). The purpose of such damping is to eliminate the influence of the low-frequency head on the midrange. Then you need to put fluffy cotton wool in the glass and you can put the midrange speaker in place. First check that its phasing is correct.

When you connect a 1.5V AA battery + to + the speaker, a - to - , the diffuser moves forward. Checking phasing is important! We solder the wires to it (+ according to the diagram to + on the speaker) and place them in the housing through the rubber gasket, between the midrange and the glass. Rubber 2-3mm thick. It is convenient to use window rubber insulation made in the form of hollow tubes and with a self-adhesive side.

We install the speaker, seal it with plasticine and screw it on top with a nameplate, placing rubber gaskets on the screws between it and the speaker. It is better not to install a protective grille - it spoils the sound. Have you seen good imported speakers with grilles on the speakers? When installing 6-GDSH-5 under the nameplate, you will need to put rubber gaskets about 1 cm thick on the screws.

More about the midrange speaker. If you don’t want to install another midrange, you can modify the old one, for example like this. Although if you have a speaker with a rubber, rather than fabric, surround, it’s better to go for the 6GDSH!

6) Vata:

This sweet word is cotton wool... It greatly affects both the overall sound and the bass in particular! So one day I reduced its amount by half. The speakers began to emit not bass, but some kind of hum...

So, we sew a couple of gauze bags (35 cm by 35 cm) and fill them with cotton wool from the 2 sausages that were removed from the body, so that almost the entire sausage goes into the first bag, and less than half of the second into the second bag. Fluff the cotton wool. We place these bags in the upper part of the case under the slot for

HF and next to the midrange glass. We fluff the remaining half of the cotton sausage and simply throw it on the bottom of the column, on the filter wrapped in felt. In my opinion, this is the best placement of cotton wool in these columns.

7) HF head.

Solder according to the diagram. We put it into the body through a rubber gasket and screw it on top with a nameplate. We also don’t install a protective grille!
Uhh... A hell of a job has been done, but there is very little left! Let's continue.

8) woofer.

We solder it (it is advisable to check the phasing, as well as the midrange) and place it through a rubber gasket (required!), fasten it with bolts, again through rubber washers and seal it with plasticine sealant. We put a nameplate on top.

9)End of assembly.

We install the plastic front, tighten all the bolts and wipe the front panel.

Yes - a few little things (quite important!): run the wires to the HF and MF under a layer of sound absorber, and wrap them around the LF; carefully check the phasing, keep in mind that the bass and midrange in the S-90 are connected in antiphase; be sure to place the speakers on rubber pads; remove all parts from the plates of the disconnected HF and MF dividers, and cover them with a sound absorber; don't skimp on wires; remove the grilles; do not suffocate the volume; the bass reflex pipe must communicate freely with the surface of the speaker diffuser; gauze is clamped inside the bass reflex pipe - it is needed there; Place the speakers on spikes (for example like this); It is better to immediately solder the connecting cable to the filter; it is much cheaper than buying good connectors.

1. Small housing volume for woofer. The consequence is a muttering of low frequencies.
2. The bass reflex is designed for a frequency of 20 Hz. The consequence is large low-frequency distortion.
3. Worthless midrange speaker. The consequences are disgusting midrange and overtones.
4. Low resonance frequency of the tweeter. Consequences - "quacking", hissing.
5. The filter is designed taking into account the previous shortcomings. The consequence is that when modifying any unit, the filter must be changed.
6. The body is not rigid enough and is not “damped”. Consequences - vibrations, overtones, "barrel".
7. Etc. etc. ...

We study and dare

While drinking beer, we reach three truths. There are three ways:

1. Lightweight and effective.
2. Medium difficulty. More shamanism and snobbery. Some sound improvements compared to point 1.
3. Super complex, time consuming and super efficient. In reality, you are trying to make new speakers. It all depends on the quality of workmanship and musical flair. If nothing works out, then no one promised you anything.

Attention! Attention! Attention!

1. When carrying out all work, ensure that the phasing of the speakers is correct. If you have not encountered this yourself, invite a specialist - electronics!
2. Remaking the speaker 15 GD - 11A is an irreversible process. If you are not careful, the speaker has one path - to the trash can, and you have another - to the market.

The first way. Lightweight and effective.

1. Mid frequencies are the main emphasis. By reworking the speaker, we will make it work in piston mode, increase the upper limit frequency, remove overtones, increase sensitivity, improve directivity, and dampen it.
2. Let's move the speaker to the range of 31.5 Hz, instead of 20 Hz. There will be less muttering.
3. Let's suppress the resonance of the high-frequency head.
4. Let's quiet the sounds of the building

We buy a Soviet tennis ball from a store. Chinese and others are not suitable. They have different material. The ball should be exactly the same as in distant childhood for 8 kopecks. As a last resort, you can take it from friends or in the tennis sports section. We buy epoxy resin (a little, maybe 1 cm cube), glue (Super Cement, Mars, Argo, etc. - hard after hardening), a couple of simple pencils, any medical bandage and cotton wool.

Let's get creative. We saw the ball in half along the seam. The seam is visible to light. It is overlapped and 1 - 2 mm wide. You need to cut in the middle of the seam. I sawed with a Nev blade, having previously made notches on it with a sharpening stone. After sawing, align the cut line on sandpaper and sand the outer surface of the ball with fine sandpaper. If there are large deposits inside the seam area, then they also need to be removed. When working, the ball must be secured with plasticine on a Mars battery (a film case, a jar of fish food, etc., according to your imagination) at three points. That's enough. Plasticine is removed later either with a dry cloth or by wiping with gasoline. Once the surface of the ball has been treated, do not touch it with your hands. Grind the pencil leads on sandpaper.

Dilute epoxy resin with double the amount of hardener. Cover the surface of the ball with the thinnest layer. If necessary, excess glue can be removed with newsprint. Sprinkle with graphite and shake off excess. It is necessary to ensure that the white plastic of the ball does not show through the graphite. If it shows through, it means the layer of epoxy resin was small. Need to add. Once everything is done, let it harden.

Assembling a 3 KHz filter. To do this, we take a 4.7 Mf capacitor and a 0.6 mH inductor. You can take a capacitor from 4 to 7 mF and adjust the inductor to it. In order not to bother your head with unnecessary formulas, the simplest thing is that the product of the capacitor capacitance in microfarads and the inductance of the inductor in mH should be equal to 2.82. Let's say the capacitance of the filter capacitor is 6.6 μF (MBGO and MBM with a permissible deviation from the nominal value of ±10%), then the inductance of the coil is 2.82: 6.6 = 0.43 mH, (the winding contains 150 turns of PEV-1 0.8 wire , wound on a frame with a diameter of 22 and a length of 22 mm with a cheek diameter of 44 mm). Using these data, it is possible to assemble a circuit without an LC meter, since it is not the exact value that is important, but the “capture” of the resonant frequency, which has a certain spread. We attach the capacitor and inductor to a piece of fiberboard and solder one terminal of the coil to the terminal of the capacitor. We solder wires 40-50 cm long to the free terminals.

Let's disassemble the column. We remove the low-frequency speaker, the mid-frequency speaker, take out the glass from it, remove the high-frequency speaker, remove the decorative trim, remove the phase reflex (on some speakers you will have to unscrew the filter). We take half of the dried ball, polish it on the outside with suede or newsprint and glue it over the dust cap of the mid-range speaker head with hard glue. You need to make sure that there are no un-glued gaps between the edge of the ball and the cap and that the ball is glued exactly in the center. We do the same with the second midrange driver. Leave to dry.

We screw a homemade filter onto the back wall of the speaker (inside) opposite the tweeter. Solder the wires from the filter to the output of the high-frequency speaker. Which one goes where does not matter. We remove the connectors from the back wall of the speakers and solder the wire going from the amplifier directly to the filter. We saw off 10 cm from the phase reflex pipe with a hacksaw along the center line. We wrap the phase reflex pipe and the mid-frequency speaker glass with a layer of gauze and bandage it. It is necessary to check whether they will enter their nests after this procedure. If they do not fit, then reduce the layer of cotton wool and gauze. We check if there is cotton wool and gauze in the glass. Add if it’s not enough until it’s full. We dampen the mid-frequency speakers. To do this, we additionally cover their diffuser holders with foam rings made from 10x27x355 mm blanks. the ends of which are glued end-to-end with Moment glue. We cover the bottom and ceiling of the column from the inside with felt (batting, padding polyester, etc.). We wrap the wires with a bandage.

We place the bandage along the wire and twist it, wrapping it around the wire. It is convenient to secure the bandage with threads. Assembling the column. We coat all the perimeters of all speakers with plasticine. There is no need to wear protective nets, but only on the condition that there are no small children, the wife will not come in with a mop or vacuum cleaner, and that the speakers will not be transported. Turn on the speakers. We don't know right. We call our friends. Please bring your favorite recordings. Let's listen. We calm our friends down with beer. We note with mockery how useful the bucks spent on purchasing foreign rubbish would be to them.

The second way. Medium difficulty.

We do everything indicated in path 1, but do not collect the columns.

1. Let's improve the properties of the body and kill overtones and the "barrel"
2. Let's achieve better signal transmission
3. Housing sealing. Removing the influence of the body

So, let's go. Strengthen the rear wall of the case by placing two slats with a cross-section of 3x2cm. vertically along the entire length at a distance of 15-20 cm from each other symmetrically, and attaching them with screws to the back wall. Pre-treat the mounting area with epoxy. It is necessary to take into account the possibility of installing a phase reflex later. Between the rear and front walls we install a spacer rail at the level of the midrange head, taking into account the possibility of installing a glass. We coat all wall joints and corners from the inside with silicone glue such as "Bison" or plumbing silicone putty. We cover the entire body inside with felt (batting, padding polyester, etc.). It should not be thicker than 1.5 cm, so as not to greatly reduce the internal volume of the case.

We reject all proposals to replace 15 GD-11A with 6 GDSH-5. Ours is already “cool”, and such a replacement will lead to a loss of power, a decrease in the dynamic range (very dangerous) and you will have to greatly change the filter. So, when replacing 15 GD - 11A with 6 GDSh-5 for 35AS - 212, you will have to replace the following parts: L1 - 0.22mH, C2 - 1.0mF, C8 - 0.5mF, L4 - 0.1mH. New parameters have been specified. When using 6 GDSH - 5 - 4, you will also have to install an additional resistance in the circuit of this head at 4 Ohms. The appearance of the column also changes. Well, if you really want to, then you can. Next. Removing tone switches. Remove unnecessary resistors R (1, 2, 4, 5, 7, 8, 9, 11, 12). We replace the wires on the filter mounting with a copper wire with a diameter of 1.2 mm. We replace the wires going from the speakers to the filter with more traveling ones. For the low-frequency speaker - multi-core - with a cross-section of 2.5 - 3 mm square, for the mid-frequency - 2.5 mm square. For high frequency - 2 mm square. - single-core. All wires are soldered to the filter directly, rather than passing through previous speakers. The filter is installed at the bottom of the column. All wires are laid under a layer of felt. On the side walls.

The filter regulators are removed. In their place, we make wooden (chipboard, plywood) plugs according to the thickness of the body. We pour them onto the epoxy and sand them down. We cover the front panel with self-adhesive wood-look film to match the veneer of the speakers. Installing speakers. Low-frequency and mid-frequency through rubber gaskets. Rubber from window insulation, thin rubber medical hoses, silicone hoses (worse) are suitable. We treat the installed speakers around the perimeter with plasticine or non-hardening window putty (it resembles a bar of laundry soap and is cheap). Checking the sound. We're just fooling around. We push aside all sorts of “Pioner”, “Technics”, JAMO and ...

The third way. Super complex, time consuming and super efficient.

It’s a good idea to have the following instruments: an oscilloscope, an audio frequency generator, a digital multimeter, an LC meter. A person who does not do repairs and assembly at home, of course, does not have all this, but there is a way out - go to the workshop and ask to try on what you need, taking with you filters, heads, etc. If they ask for payment for this, it will be purely symbolic. You can even order a filter. This, of course, will be more expensive. Let's begin. We take as a basis 35AC-212 with dimensions 710x360x285. It is desirable that the case be made of plywood, a woofer with a rubber surround, and a high-frequency speaker with a fiberglass dome. Let's sort everything out. We no longer need the midrange speaker. The housing needs to be increased for a woofer with a rubber surround to 100 liters. If the suspension is polyurethane foam, then up to 120 -130 liters. Our body is 70 liters.

There are two options:

1. Remove the front wall from the case, in order to later use it for a matrix for the holes for the speakers in the newly manufactured case for 100 liters. The remains of the buildings make good boxes for potatoes and markoshka in the cellar.
2. You can try to build up the old body.

In the first case, you need to focus on the dimensions - 1100x360x350 and production in a furniture workshop according to your drawings, with abuse and quibbles about quality. We will consider the second way. So, you can try to get by with a little blood. We make it ourselves, or we order two boxes with tightly fitting walls and lids made of double 10-layer plywood with external dimensions - 380x360x285. We cut out identical holes approximately 270x210 in the bottom of the column and in the lid of the box. We cover the inside of the box with felt. After assembly it will be impossible to do this. We drill holes in the lid of the box and in the bottom of the column through which we fasten them together with bolts. The bolt heads should sink into the countersunk area. Add a little bit of shot - 10 kilograms of shot won't hurt, throw a gauze bag with cotton wool on top. We pre-fill the joint with epoxy with a normal content of hardener. We cover the joint with felt. The rest of the body movements are the same as in paths 1 and 2. Let’s take the mid-frequency head 30 GDS-1. You just need to check them - there are a lot of defects. Purely mechanical properties. Next. We measure f resonance of all speakers. You can sign directly on the magnets with a felt-tip pen so you don’t get confused and try everything on again.

It would be good if the resonance frequency of paired speakers did not differ greatly. If the speaker produces extraneous sounds at any of the sound frequencies, then it must either be cleaned or replaced if cleaning did not achieve normal operation. We calculate and make filters for our case. The fewer inductances, the better. We continue to work with the body. Remove excess resin at the joint. Let's polish it. We make two wooden boxes for filters. We will mount them on the back wall from the outside. We solder the wires from the amplifier directly to the filters. And we will drag the wires to the speakers through the fastenings of the speaker connectors. All wires are branded audiophile ones. Choose your own price category. There’s just no point in taking very expensive ones. It is better to convert the bass reflex to a frequency of 31.5 - 40 Hz. If the dome of the high-frequency head is made of lavsan, then, after removing the crosspiece, you need to coat the suspension and the outer third of the dome with perchlorovinyl. We cover the entire body with self-adhesive film. For the rest, see path 1 and path 2. With mandatory step-by-step verification - better - worse. The best method, if there is no obvious result, is blind listening.

Literature

1. Zhagirnovsky M., Shorov 8. Improving the sound of 35AC-1 and its modifications. - Radio, 1987, No. 8, p. 29, 30.
2. Shorov V. Improvement of loudspeaker heads. - Radio. 1986, no. 4, p. 39-41.
3. Aldoshina I., Voishvillo A. High-quality acoustic systems and emitters. - M.; Radio and communications. 1985.
4. Zhbanov V. Mechanical damping of diffusers. - Radio, 1988, No. 5, p. 41-43.
5. Maslov A. Once again about the modification of the loudspeaker 35AC-212 (S-90). - Radio, 1985. No. 1, P. 59.
6. Zhbanov V. About damping of dynamic heads. - Radio, 1987, No. 8, p. 31-34.
7. Gennady and Karen Arzumanov. On the issue of modernizing acoustic systems. Bulletin of A.R.F. No. 6" 2000

Refinement of the S90 or how to make them “sing” at minimal cost

• DIY or Do It Yourself

How it started

Let's climb inside

Let's start with the tweeters

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

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

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, since 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

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.