What is the internal volume of the s90 speakers. Refinement of the S90 or how to make them “sing” at minimal cost. Speakers and other "trifles"

This page shows diagrams of Radiotehnika class S90 speaker systems (35AC-212, S90, S90B, S90D, S90F, S-90E), detailed description, 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 specifications S-90:

Rice. 2. Schematic diagram 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 another model speaker system"S-100D", it uses a 30 GDS-3 mid-frequency head 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

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 sound programs in combination with various types 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-90s (S-90b, S-90F, etc.), their analogues (Orbita, Amphiton, etc.), as well as to homemade speakers. Main criterion- 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 take out 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 loud 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 the switches from the circuit, replace the wires with audio made of oxygen-free copper, solder the speakers directly to the filter, solder the supply 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 one you can have 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 (sintepon), 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, negative reviews no, 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 closing the windows of the diffuser holder for back side dynamics with a layer of foam rubber 0.5-0.8 cm thick. Quilted batting is also suitable. 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 from a felt boot that is suitable in height and width, 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, and - 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 driver, 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.

27122

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, an error led to the fact that the potential for high-quality reproduction originally inherent in the Radiotekhnika S-90 model and its modifications low frequencies, 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 They are trying to improve the low frequencies of these speakers by witchcraft with filters, reworking 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 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 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. Presented on the Internet big number attempts to remake the S-90 speakers in order to “deceive everyone” and turn 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 and poor quality bass;
• 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 settings give wide strip 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.

The first domestic speaker that meets the requirements for Hi-Fi equipment (initial letters English words high fidelity – high quality, high fidelity of sound reproduction), the speaker system "S-90" 35AS-012 was born: three-way, bass reflex type, loudspeakers 30GD-1, 15GD-11, 10GD-35 are used. On the basis of this model, the acoustic systems 35AC-016 (with a bass reflex), 35AC-018 (with a bass reflex), 35AC-008 (closed), 35AC-015 (with a passive radiator) were created. They all have similar parameters and differ in appearance. Currently, this one, to some extent, has ceased to satisfy the needs of lovers of high-quality sound reproduction. Considering that the current market offers a fairly wide range of expensive modern acoustic equipment, but not always of high quality, we will consider options for improving a pair of acoustic systems "S-90" 35AC-012, produced in 1985 by the Riga Radio Plant named after. A. S. Popov, equipped with newer, at that time, developments of low-frequency, mid-frequency heads - 30GD-2 and 15GD-11A. Fundamental electrical diagram and the layout of the AC filter parts are shown in Figure 1.

Rice. 1. Electric filter for the acoustic system "S - 90" 35 AS-012: a - circuit diagram; b – arrangement of elements on the board

Capacitors C1, C2, C4-7 are used as MGBO-2, C9, C8 – K73-11. The filter elements are mounted on 12 mm plywood with dimensions 210 x 160 mm. The inductors are installed in a horizontal position and, moreover, L1, L2 and L3, L4 are close to each other, respectively. The filter itself is mounted on the rear wall inside the speaker housing behind the woofer head.

Frame

Carefully remove the protective grilles of the heads and the heads themselves, the filter and other elements that will limit access to the internal surfaces of the housing walls. Carry out leakage prevention. Coat the joints of the walls and the seats for the woofer and midrange speakers from the inside with a silicone sealing compound. Seal the gaps between the rear, side, bottom and top walls on the outside of the case with silicone (if necessary), having previously cleaned them of dust, dirt and glue. In order not to stain the veneer trim of the case with sealant, cover it around the cracks with paper construction tape. Excess sealant is removed. After it has hardened, use a sharp knife to make a shallow cut under a metal ruler along the edges of the adhesive tape, where it meets the sealing compound. The tape is removed. The sealant is used to match the color of the body or transparent.

Among many radio amateurs who are modifying the “S-90”, a common means of combating vibrations of panels is to increase their rigidity by using additional “stiffening ribs” (bars), spacers, etc. They also additionally coat the internal walls with a sound absorber. Which is not always justified, since such measures lead to a decrease in the internal volume of the case, which, in turn, reduces and even eliminates the efficiency of the bass reflex.

Simply increasing the rigidity of the walls by using additional “stiffeners” or thickening the panels only increases the resonant frequencies of the panels and changes the nature of the distribution of their vibrations and radiation, since the number of vibrating surfaces and their sizes change. Thickening the panels also increases the weight and cost of the design. Therefore, for the manufacture of decoration, it is more advisable to use materials that have increased internal losses of vibrational energy during their deformation (increased “internal friction”), as well as sufficiently high elasticity. Such materials, called vibration-damping or vibration-absorbing materials, can be applied to ordinary panels. Vibration-absorbing materials convert part of the vibrational energy of vibrations into heat and increase the mechanical resistance of the panels, thereby reducing the amplitude of vibrations. Vibration damping is especially effective at resonant frequencies, when the amplitudes of vibrations and bending or shear strains increase. The use of a vibration-absorbing coating on acoustic design panels leads to an increase in the overall rigidity of the panel, and therefore it seems possible to reduce the thickness of the panels by 1.5 - 2 times without fear of increasing their vibrations. Therefore, self-adhesive vibroplast with a thickness of 1.5 - 2 mm is applied to the inner surfaces of the walls of the modified speakers (a flexible and elastic vibration-absorbing material, which is a polymer self-adhesive composition backed with aluminum foil, Fig. 2, is used to reduce vibrations of car body parts).

Rice. 2 Vibroplast

For an ideal tight fit to the surface of vibration-isolating materials, the inside of the housing wall must be prepared. Namely, sand with medium-grain sandpaper and prime, for example, with nitro varnish or PVA glue. After this, the necessary blanks are marked and cut out from a piece of vibroplast (some materials have special markings in the form of molded squares 1 x 1 cm, which allows you to do without a ruler and marker). Bend a corner on the workpiece protective film and apply it to the intended place. Apply the edge of the material to the surface and gradually, carefully smoothing it, while removing the film, stick the entire piece. The material is finally rolled using a roller, achieving maximum fit.

The sound-absorbing coating increases the sound absorption of lower frequencies to 500...1000 Hz. The degree of sound absorption should be proportional to the surface area of ​​the coating. If you mount it on the walls of the housing not closely, but at a distance of 20 - 50 mm from them, then sound absorption at frequencies below 500 Hz increases. This condition completed by the manufacturer 35AC-012 - mats with cotton wool in sufficient quantities are located at some distance from the walls (approximately in the central part of the box). Therefore, additionally covering the walls with a sound absorber is not only useless, but also harmful. Rolls or pillows of sound-absorbing material suspended in the geometric center of the speaker give the same results as placing it on the walls of a box.

Rice. 3. Sealing the seams of the bass reflex tunnels

The design of the bass reflex port 35AC-012 has the shape of a curved tunnel with an unusual cross-sectional configuration. This is due to the purpose of satisfying the following conditions: rigidity and absence of resonant sounds in the port material. It consists of two plastic parts glued together. The gluing areas are inspected. The cracks found during inspection are filled with dichloroethane. Then, at these points, both parts of the bass reflex port are tightened with clamps and dried - fig. 3. It will also be useful to cover its walls with strips of vibroplast. After this treatment, the plastic of the port becomes hard and dull. It is recommended to install an acoustic impedance panel (APP) at the output of the bass reflex port. This technical solution, protected by USSR copyright certificate No. 577699, allows you to reduce the acoustic quality factor of the loudspeaker head several times. An acoustic system with such a PAS sounds more natural, without “mumbling”.

The weakest link

The frequency response of the mid-frequency dynamic head 15A - 11A has a sharp decline above 4.5 kHz - fig. 4, a, the acoustic quality factor is about 11.8. And the higher the quality factor of the oscillatory system, the more it emphasizes frequencies that coincide with resonant ones, or close to them. Which, practically, eliminates the possibility of obtaining full-fledged undistorted sound when turning it on through a midrange bandpass filter, unless the necessary measures are taken. To eliminate the first drawback, use the following method.

Rice. 4. Mid-frequency dynamic head 15GD-11A (20GDS-4-8): a – frequency response of sound pressure; b) – dimensions and installation dimensions

Soak the dust cap of the head with nail polish remover, you can use solvents 646, 647 and others. Carefully remove it with a scalpel (Fig. 5, b). Remember that due to the strong effect of the field of the magnetic system on a steel instrument, careless movements can damage the speaker elements! Next, wipe off the glue diffuser with a cotton swab dipped in the same nail polish remover. Apply Moment glue to the lower part of the horn and the upper part of the voice coil. Dry for 10 - 15 minutes. Again, coat both parts and immediately connect them, pressing lightly (Fig. 5, e). The horns are installed both new and extracted, as described above, from old speakers (Fig. 5, c).

Rice. 5. Gluing the horn to 15GD-11A: a - dynamic head 15GD-11A; b - removing the dust cap; c - dynamic broadband head 10GDSh-1-4 (10GD-36K); d - high-frequency horns 10GDSh-1-4; e – stages of adjusting the horn for 15GD-11A

The glued horn is designed for the 10GDSH-1 dynamic head. For our case it should be adjusted. Fitting consists of trimming it while measuring the frequency response of the speaker. To do this, place the speaker on the same axis with the microphone (preferably a measuring one), within 40 - 50 cm, in the room no closer than 1 meter from walls, furniture, etc. The microphone is connected to the corresponding port of the computer video card, and the speaker is connected to the amplifier computer speakers. Launch the RightMark 6.2.3 program and measure the frequency response. Cut off the edge of the horn, about 1 cm. Measure the frequency response and compare it with the previous one. The operation is repeated until the most even frequency response is obtained in the mid-frequency range, thereby increasing their range to 10 kHz (Fig. 6).

Rice. 6. Amplitude-frequency response of the 15GD-11A head with an additional high-frequency horn

The second and subsequent cuts should be carried out very carefully, cutting off no more than 3 mm. As a result, the lateral surface of the horn inside was about 7 mm (from the dust cap to the edge of the trim) - Fig. 5, d. Trimming is done with nail scissors, since they turned out to be the most suitable tool for this type of work; they have miniature rounded cutting surfaces. To impart rigidity, the cut edge is impregnated with BF-2 glue slightly diluted with ethyl alcohol.

To eliminate the second drawback, acoustic damping of the head using PAS is used. Damping the heads with sound-absorbing material is less effective and, moreover, helps to increase the resonant frequency. In order to increase the efficiency of the action of the PAS on the moving system operating in the acoustic design of the head, the damping fabric should be located as close as possible to the diffuser. It is most rational to arrange the PAS in the holes of the diffuser holder. To do this, eight identical elements are cut out of thick cardboard approximately 2 mm thick (Fig. 7, a). The total area of ​​the holes for the 15GD-11A head should be 22...28 cm2. One side of each element is smeared with instant glue. After 5 minutes, paste onto stretched cotton fabric using an embroidery hoop. After 30 minutes, the fabric is cut around the elements. The PAS elements are slightly bent and glued into the windows of the diffuser holder (Fig. 7. b). The gluing areas are additionally coated with glue. It is important that the fabric in the holes of the elements is stretched, otherwise there will be no effect from using the PAS! Application of PAS, i.e. acoustic damper, allows you to slow down the natural vibrations of the diffuser, as a result of which the “after-sound” time will significantly decrease and the sound quality of the speaker will significantly increase.

Rice. 7. Head 15GD-11A: a - PAS element; b - PAS in the windows of the diffuser holder

The damping effect of the PAS for the dynamic head 15 GD-11A is graphically presented in Figure 8.

Rice. 8. Damping effect of PAS for head 15GD-11A

The effectiveness of using PAS was tested by employees of the Berdsk Radio Plant. In particular, the harmonic coefficients of the 15GD-11A mid-frequency head with and without PAS were measured. The measurement results shown in Table 1 show that the PAS can significantly reduce harmonic distortion in the frequency range in which the human ear is most sensitive.

Table 1. Harmonic coefficients of the 15GD-11A head

To restore elasticity, the rubber-fabric suspension is impregnated with “Air conditioner and drive belt tensioner” aerosol. After this modification, the frequency range of the head increased significantly, up to 10 kHz (!), the linearity of the frequency response of sound pressure and, most importantly, the sound quality of the speaker system as a whole improved.

Separation filters

In passive coupling filters, their design plays an important role, as well as the choice of specific elements - capacitors, inductors, resistors, in particular big influence The characteristics of speakers with filters are affected by the relative placement of the inductors; if they are poorly positioned due to mutual coupling, signal interference between closely spaced coils is possible. For this reason, it is recommended to place them mutually perpendicular; only such an arrangement can minimize their influence on each other. Inductors are one of the most important components of passive coupling filters. It is not recommended to place the coils closer than 100 mm to each other. The simplest way modifications to filter 35AC - 012 (Fig. 1, b) - reinstallation of coils L1 and L3 perpendicular to the base and each other. For this arrangement, plastic corners are used, cut out from old equipment cases or boxes. Particular attention should be paid to the base material on which the filter parts are placed. It must be made of dielectric! In some acoustic systems, 35AC-1, "S-90" 35AC-212, predecessors "S-90" 35AC-012, the installation of filter parts is made on a steel plate, the magnetic properties of which negatively affect the inductors and, naturally, sound quality.

The 10GD-35 high-frequency head is shunted with a notch filter tuned to its main resonance frequency of 3 kHz. It is a high-Q series LC circuit. The capacitance of the circuit capacitors is 6.6 μF (MBGO and MBM with a permissible deviation from the nominal value of ±10%), the inductance of the coil is 0.43 mH, its winding contains 150 turns of PEV-1 wire 0.8 mm, wound on a frame with a diameter of 22 and a length 22 mm with a cheek diameter of 44 mm. The use of filter elements of the acoustic system 10AC - 401 for these purposes will significantly reduce the costs and labor intensity of the work. The product of the capacitor capacitance in microfarads and the inductance of the inductor in mH should be equal to 2.82 (http://www.radiolamp.ru/acoustics/3/). If 2.82: 6.6 = 0.43 mH, then for a circuit with an inductance of 0.5 mH it is easy to calculate the capacitance of the capacitor: 2.82: 0.5 = 5.6 μF. You just need to select the capacitors to the required capacity - 5.6 µF.

Another modification option is to unwind the 0.5 mH inductor, the extra turns to the required 0.43 mH. It is convenient to use an RLC meter. In place of the filter resistor of the acoustic system 10AC - 401 (previously removed as unnecessary), a 2 μF capacitor is reinstalled, and in its place a 4 μF capacitor of the same type is attached - MGBO. MBM capacitors are soldered to the terminals of the capacitors to set the capacitance of the required value of 6.6 μF (Fig. 9). As a result of the described modification, the 10GD-35 head gets rid of overtones, rattling and characteristic “hissing”.

Rice. 9. Filter of the acoustic system 10AC - 401, converted into a notch filter for the HF head 10GD-35

Conductors

The cable connecting the speaker and amplifier makes a certain contribution to the sound of the system. Mainly due to the fact that the cable has a certain resistance. The influence of this resistance not only affects the sensitivity of the speakers, but also affects the distribution of power between the emitters in the speaker. To eliminate this effect as much as possible, the cross-sectional area of ​​the wire should be as large as possible and the length as small as possible. In addition, it is necessary that for all speakers the length and cross-section of the wire are the same. It also cannot be ruled out that the conductor has a certain inductance, and two closely spaced conductors form a capacitance. In this regard, the dual wire can be considered as an LC low-pass filter. That is, the longer the wire, the more the high frequencies will be damped. In practice, the influence of wire inductance appears only when the cable length is over 50 m. Also, when high-level low-frequency sound current flows through an acoustic wire, a strong magnetic field is formed around the cable conductors. This field affects the currents flowing through these conductors sound signal mid and high frequencies, resulting in the sound of the speaker system becoming less clear and transparent. The solution to these problems is to ensure the flow of currents of low-frequency components of the signal and currents of its mid- and high-frequency parts through physically separated conductors. To do this, an additional pair of sockets (screw terminals) is installed in the speaker system, to which the input of the midrange and high-frequency loudspeaker filters is connected. Thus, the woofer filter input is connected to a separate pair of input terminals. This connection is called “bi-wiring”, i.e. in two pairs of wires to one speaker. The use of two- and three-pair communication cables with a load makes it possible to significantly reduce the total cross-section of conductors without increasing the mutual influence of loudspeakers. Such acoustics with a double set of terminals can also be connected to separate amplifiers, which will already be called “bi-amping”, i.e. two amplifiers per channel. In the latter case, the electrical interaction of the emitter sections is also eliminated. Instrument threaded terminals are used as screw terminals. The material of the stud is brass, the thread is M6 x 0.5, the wing is covered with ABC plastic.

The most important criterion for choosing a conductor for a speaker is its electrical power. The electrical power P supplied to the loudspeaker is understood as the power dissipated by a resistance equal in value to the nominal electrical resistance R n, with a voltage equal to U at the speaker terminals: P = U2/R n. In the practice of designing domestic speakers, two types of power were usually used - nominal (electric power limited by the occurrence of distortions exceeding set value) and nameplate (the highest electrical power at which the loudspeaker can operate satisfactorily for a long time on a real sound signal without thermal and mechanical damage, usually 1.5...2 times higher than the rated power). According to technical documentation "S-90" 35AC-012, rated power P nom. = 35 W, passport R passport. = 90 W. The manufacturer of these types of dynamic heads allows their operation with a voltage not exceeding 11 volts. In this case, the current strength I flowing in the voice coil of the woofer head will be equal to 2.8 A, and in the voice coil of the midrange loudspeaker - 1.4 A. To calculate the cross-section of the conductor, it is necessary to proceed from the indicated current values.

Note. The calculation is performed in a simplified form, provided that there is only active resistance in the circuit, at which the cosine of the phase angle of the current and voltage φ is equal to zero. In real electrical circuit A loudspeaker always contains inductive and capacitive reactances, called reactive reactances, which introduce temporary changes in current and voltage values.

Musical works are variable in nature, both in signal level and frequency, so a current of 2.8 A can theoretically occur, but not constantly and in very short sections of the musical path, for example, during the “thumping” of a bass drum. The internal installation of "S-90" 35AC - 012 is made with tinned copper stranded wire in PVC insulation with a cross section of 1 mm 2, which corresponds to the calculated data, since the current density in the copper conductor is 6 - 10 amperes per square millimeter. Please note that the voice coils of the loudspeakers are wound with wire of a much smaller cross-section: 30GD-1 - 0.1 mm 2, 15GD-11A - 0.02 mm 2, 10GD-35 - 0.005 mm 2. The total cross-section of the wires of all coils is 0.125 mm 2, eight times thinner than the internal speaker wire! In the power supply circuits of power amplifiers of the "S-90" era, rated power from 25 to 50 W per channel, fuses were provided for a current of 2 to 3 A, and this, first of all, to power the circuit and then the load.

The actual sound signal is pulsed in nature. On a signal with steep fronts, even at frequencies in the audio range, the skin effect (from the English skin - outer layer, shell) is significantly manifested - the effect of displacement of current to the surface of the conductor, which leads to an increase in the effective resistance of the connecting cables. .

Low-frequency signals propagate throughout almost the entire volume of the conductor, and the propagation of high-frequency signals occurs mainly in a thin near-surface layer. This skin effect dramatically increases the resistance of the conductor and slightly decreases its inductance. Figure 10 shows the frequency dependence of the impedance of copper conductors various diameters 1 m long. At f 100 kHz, inductance plays a dominant role. A copper wire with a diameter of 0.16 mm up to a frequency of 20 kHz does not change its resistance, but has a relatively large value, almost 1 Ohm. Significantly reduce the conductor resistance and leave it unchanged throughout the entire strip audio frequencies The use of several core insulations with a diameter of no more than 0.16 mm will allow. A bundle of enameled wires intertwined in a special way (from German Litzen - strands and Draht - wire) is called Litz wire.

Rice. 10. Frequency dependence of the impedance of round copper conductors 1 m long

Thus, speaker cables must not only have minimal resistance and inductance, but also have minimal skin effect. Connecting loudspeakers, especially mid-high frequencies, is best done with Litz wire or copper wire coated with a thin layer of silver. Silver has the highest conductivity of all metals, and its thin layer, in which, thanks to the skin effect, most of the current flows, has a strong influence on the active resistance of the conductor.

When choosing a mounting wire, it is also necessary to take into account the principle of connecting acoustics through 2 pairs of contacts, which, naturally, proportionally distributes the power between the low-frequency and mid-high frequency channels. With equal sensitivity of the heads, the maximum noise (nameplate) power at the crossover frequency, in our case, 500 Hz for the LF channel is 56% of the total power, and for MF-HF is 44%. Between the midrange and high-frequency heads, the power at a cutoff frequency of 5000 Hz is distributed at 41.5% and 2.5%, respectively. This division of power cannot be considered unconditional, but gross errors in calculations can be avoided. Speaker heads differ both in sensitivity and in the value of nominal electrical resistance (Table 2). The difference in each of these parameters leads to the need for an appropriate selection of the voltage supplied to the head to obtain a uniform frequency response in pressure. And the voltage supplied to the head is one of the dominant indicators affecting power.

Table 2. Main parameters of heads used in acoustic systems "S - 90" 35AC - 012

Note. Information about the parameters is taken from many sources, not always comprehensive, and sometimes contradictory (indicated in parentheses).

It should be noted that, in home acoustic design, the influence of conductors on sound quality is negligible compared to other factors. Attention should be paid to more important elements, the acoustic properties of the room, and the correct placement of equipment. Information about the exclusivity of cables made of oxygen-free copper, from wires with the “orientation” of the surface layer of the conductor, affecting the passage of an audio signal in one direction or another, is nothing more than advertising.

Electrical part of the modified system

The electrical circuit diagram is shown in Figure 11,a. The filter uses capacitors with a maximum operating voltage of 160 V: K73-11 (C1, C10, C11); K73-16 (S2-4); MBGO-2 (C5 – 9); MGBO-2 and MBM (C13) connected in parallel. Installation is carried out with a single-core copper wire with a cross-section of 1 mm 2 (extracted from a communication cable with air insulation of each core) and a MGShV wire (flexible stranded, conductive cores made of tinned copper wire, wrapped in electrical insulating silk with PVC insulation, for intra- and inter-unit installation of various electronic equipment and devices for rated voltage up to 1000 V alternating current frequencies up to 10,000 Hz), sections 1.5 mm 2 (for the low-frequency section) and 0.5 mm 2 (only in the mid-high frequency filter). The connection between the terminals, the divider, the filter and the HF head is carried out using a LEPHD wire 500 x 0.05 (round wire 0.98 mm 2 with a core twisted from 500 copper wires with a diameter of 0.05 mm, insulated with polyurethane-based varnish, with a two-layer winding made of natural silk, recommended for the frequency range 250...500 kHz, with electrical resistivity, at 20˚C, 0.0158...0.018 Ohm/m). The playback level control does not need to be connected.

Rice. 11. Electric filter for the acoustic system "S - 90" 35 AS-012 after modification: a - circuit diagram; b – arrangement of elements on the board

All elements are placed on the plywood of the original filter “S – 90” 35 AC – 012 (Fig. 11, b). Special attention attention should be paid to the relative position of the inductors. Parts must be rigidly secured. Connections are made with as short wires as possible, avoiding sagging. The filter elements must not touch. If necessary, for tight installation, use sealant, couplers, insulating tape, etc. Otherwise, as a result of the effects of vibrations of the housing and air fluctuations inside the speaker, the filter parts will rattle and make unpleasant sounds. The filter is attached to the bottom wall inside the housing, thereby minimizing the influence of the woofer's magnetic field on the inductors.

Speaker Installation

Before installation, first of all, the woofer and treble heads (the midrange head is already normalized) are inspected for the integrity of the structures, especially in the gluing areas, the absence of mechanical damage to the parts, and the integrity of the suspensions of the woofer. It can be rubber or polyurethane (35AC - 018). The suspension, made of not very high-quality rubber, hardens over time. Polyurethane is destroyed by sulfur impurities in the air. The problem of suspensions is eliminated by replacing them. Alternative solution For a rubber suspension that is not damaged, it can be soaked with air conditioning and a drive belt tensioner. Replacing suspensions is a very labor-intensive job that requires certain knowledge and skills. The places where the centering washer or suspension is peeled off from the diffuser holder are coated with glue with the simple name 88, after which the glued surfaces are pressed. It is also necessary to make sure that the voice coil does not touch the elements of the magnetic system. Recovery appearance The diffuser is simply painted with a black marker filled with alcohol ink (it says “alkohol” on it). Some "finishers" use printer ink. This is not the right decision, since it has the properties of quickly fading and being washed off with ordinary water. The acoustic lens at the HF head is removed to release the dome-shaped cone with the voice coil. Carefully remove it and make sure that the voice coil is intact. Very often its coils are separated from the frame during operation. If the specified defect is detected, the diffuser with voice coil is replaced with a new one. For prevention, the voice coil is coated with BF-2 glue, slightly diluted with ethyl alcohol. It is advisable to test the heads by measuring the frequency response of sound pressure. Loudspeakers that cannot be repaired are replaced with new ones.

One more effective way Reducing vibrations, and therefore unwanted overtones, is to “softly” mount the heads. They are mounted on rubber gaskets. It is necessary that the fastening elements do not come into contact with the diffuser holder. To do this, select a tube of the required diameter, for example, polyvinyl chloride, with a tight fit to the walls of the speaker mounting holes, while ensuring free entry of the screws. If necessary, the holes are drilled to the required size. Rubber washers are also placed under the mesh with decorative rims at the holes. It should be noted that the bass and midrange heads are mounted in recesses. Therefore, it is necessary to place rubber bands in four places around each speaker, for example from a bicycle inner tube, to prevent the side parts of the diffuser holders from touching the body.

Facing and decorative elements have a significant impact on the frequency response of the speakers. Decorative material covering the bass reflex hole, especially the passage, can have a significant impact due to high oscillatory air velocities. Grilles and blinds can sometimes cause resonance phenomena and frequency response loudspeaker, additional peaks and valleys will appear. The front part of the 10GD-35 head, around the acoustic lens, is covered with felt or thick fabric. This will ensure both its soft fastening and minimization of diffraction, the manifestation of the reverberation effect of sound waves, which, in turn, will weaken the resonance phenomena between the head and the grating. The acoustic system 35AC-1 has a removable decorative panel. In the technical documentation specified by the AC, it is recommended to remove the panel when listening to high-quality programs, when operating at maximum permissible power. Figure 12 shows graphs of the frequency response of the sound pressure of loudspeakers 15GD-11A and 10GD-35 in an open version (white curve) and closed with decorative mesh (green curve), provided for by the design of the S-90 35AC-012 acoustic system. No significant differences are observed. Conclusion: in this device There is no particular need to remove protective decorative grids, since their presence does not affect the frequency response of the heads in the operating frequency range. You should be guided by subjective assessments after listening to a real sound signal through a speaker system with and without decorative grids.

Rice. 12. Frequency response of sound pressure of loudspeakers: a – 15GD-11A; b - 10GD-35

Described revision technique speakers"S - 90" 35 AC - 012 will also be useful for remaking loudspeakers and other models, as well as making speaker systems with your own hands.

Literature

1. Aldoshina I. High-quality acoustic systems and emitters, M.: Radio and Communications, 1985.
2. Ephrussi M. M. Loudspeakers and their application - M.: Energy, 1976. - 64 - 66 p.
3. Molodaya N. Acoustic damping of loudspeakers. Radio, No. 4, 1969.
4. Sysoev N. Improving the sound of 35AC-012 (S-90). Radio, No. 10, 1989.
5. Burko V. Household acoustic systems. Operation, repair - Minsk: "Belarus", 1986.
6. Maslov A. Once again about the modification of the loudspeaker 35AC-212 (S-90). - Radio, 1985. No. 1, P. 59.
7. Popov P. improving the sound quality of loudspeakers - Radio, No. 6, 1983.
8. Shorov V. Improving the sound of loudspeaker 25AC-309 - Radio, No. 4, 1985.
9. Gorshenin D. Comparison of capacitors in AC crossovers. Radio, No. 8, 9, 10, 2009.
10. Kunafin R. And again 35AC... - Radio, 1995, 5, p. 19, 20.
11. Afonin S. Creation of acoustic systems at home - M.: Eksmo, 2008.
12. Bystrushkin K. Acoustics with which we live. "Stereo & Video" N 11 1997.
13. Petrov A. Sound circuitry for radio amateurs, St. Petersburg: Science and Technology, 2003.
14. Brans J. Electronic design: methods of dealing with interference, M.: "Mir", 1990.
15. Sapozhkov M. A. Acoustics: reference book - M.: Radio and Communications, 1989.

Publication date: 05.02.2015

Readers' opinions

• Vladimir / 12/14/2018 - 01:17
  Good day everyone! Today luck smiled on me! I came across your article and realized I was on my way. I have never been involved in radio electronics professionally, but I decided to improve it. I used articles that are full of them on the Internet and are not supported by deep knowledge. Vladimir, I have a not very modest request for you. I will leave my phone number (0675202057), please send me an SMS with information that will give me the opportunity to communicate with you. If, of course, you have the opportunity and desire. It’s easier for me, an amateur, to explain the essence of the problem. Thank you.
• [email protected] / 10.09.2018 - 07:31
  Dear author, hello friends! I have had an S90 since 1982 and only now I realized that they are buggy, mid and high. I spent the evening and found that when assembling the speakers, 2 technological errors were made: The first and it is the most tricky, 15GD-11A is placed in a hood, its rear is sealed and it doesn't breathe, that's why there are so many complaints about this speaker, everyone changes it to something else. IT'S SIMPLE! under the midrange speaker from the back, place 4 bushings 5 ​​mm high (you can use 4 nuts per 10 mm). Glue the nuts onto the plasticine and then install the midrange speaker and it will sing perfectly and will not interfere with the tweeter head. From the front side of the HF head, remove ALL the props, for some reason the mesh is made of steel and attracts the HF speaker with a magnet (this is not correct). Eliminate these 2 technological mistakes of the manufacturers and YOU will say. What wonderful designers came up with the S90!!!
• Author / 07.25.2018 - 18:35
  Sorry, part 4 at the following link: http://www..html Part 5 is in development, coming soon.
• Andrey / 07/23/2018 - 23:33
  Where does part 5 come from? If there are only 3 parts of modification 35ac-12. Maybe I missed something, please post a link about part 5.
• Author / 07.23.2018 - 19:19
  Follow the recommendations from part 5 of the article on replacing elements and their relative positions. A notch filter can be installed in the high-pass part of the filter. If you don’t modify the midrange head, then that’s probably it.
• Andrey / 07.22.2018 - 23:57
  Good afternoon. I have a question. There are Orbita 35ac-016 speakers with regulators. I can send you a photo of how they are located inside the filter. How and what should I improve. I can hold a soldering iron. And read the diagrams a little. Maybe someone can tell me what to do and according to what scheme. Thank you.
• Rush / 05.26.2018 - 02:42
  Great! Just pasting the case with 3mm vibration isolator has already made the sound cleaner and more pleasant. What’s good is that the S-90f has already removed everything that is possible in the filter. All that remains is to make a PAS for the account. I glued this thing https://www.ulmart.ru/goods/3774803. The result is very noticeable and pleasing. Thank you!
• Alexander B. / 05/22/2018 - 15:44
  Thank you for your reply.
• Author / 05.22.2018 - 15:17
  Aldoshina I. noted in her book that additional wall stiffeners and spacers do not eliminate resonances, but distribute them over new surfaces of the same stiffeners and spacers. But applying a material with increased internal friction to the surface of the walls allows the material to be used for walls of smaller thickness. In essence, the vibroplast virtually thickens the walls, thereby reducing unwanted resonances. Making a PAS for the midrange head is the first thing to do. The game is worth the candle.
• Alexander B. / 05.21.2018 - 15:48
  Vladimir, good afternoon. Thank you for your article. I would like to consult with you and ask a few questions. I have an S-90F (1991). After reading your article, I also decided to improve the system, but since I’m not an electronics engineer, at the minimum. 1. Cover with vibroplast, seal the cracks 2. Impregnate the speaker surrounds with air conditioning 3. Make PAS on the midrange 4. Replace the capacitors with newer ones with the same rating (without changing the filter circuit) 5. Replace the acoustic terminal 6. Place it on spikes. In this regard, the question is 1. should I install a spacer between the rear and front walls? 2. Is it possible to make PAS on the midrange and not change the filter circuit (I’m not familiar with this)? Is the game worth the candle for such a minimal improvement?
• Author / 05/16/2018 - 20:52
  Two original cotton mats are quite enough.
• Victor / 05/16/2018 - 20:11
  Greetings, Vladimir. While working on the speakers, a question arose. Maybe it’s worth pasting over the vibroplast with thin felt (1-1.5 mm) or batting in 1 layer? But something is confusing about the “aluminum” inner surface of the box.
• Author / 04/01/2018 - 13:46
  Probably to weaken resonance phenomena in oscillatory circuit coil-capacitor and equalization of frequency response. There is a whole article on the use of resistors in a filter together with coils and capacitors.
• Anton / 03/31/2018 - 18:35
  Hello! Please tell me why we need resistor R1 75 Ohm (in some circuits 100 Ohm), which is parallel to coil L2 in the RF head filter? Is it necessary to install it?
• Author / 03/29/2018 - 09:09
  It is enough to cover the suspension on one side evenly, avoiding drips. The diffuser, of course, needs to be closed. Find coils from 35AC-212(012) and wind them to the desired size - it will be easier, better quality and more reliable.
• Yuri.B. / 03/29/2018 - 08:33
  As for the coil, I am working on options from what is available: there are two sounders from a tube TV, but the cross section “w” of the core is more than about 5-6 cm2. Wire from the OS of the same phone. but it seems to be thinner. Alternatively, is it possible to connect two coils 2.5+0.25=2.75 in series if I find the same crossovers? And the question regarding the air conditioner is to treat the hangers on both sides and probably need to cover the diffuser (cut out a circular template from paper or cardboard)?
• Author / 03.28.2018 - 15:46
  Resistors can be connected either in series or in parallel. In this case, the total power is equal to the sum of the powers of the resistors used. If you decide to modify your speaker according to the method from the article in Radio No. 4 magazine for 1985, then in the diagram in Fig. 3, it is necessary to install a resistor R3 with a nominal value of 15 Ohms - this is to attenuate the signal of the 6GDV-4-8 head by half (i.e. by 3 dB). I wonder where you will get the L3 Coil?
• Yuri.B. / 03/28/2018 - 10:53
  Dear Vladimir, thank you very much again! You probably confused me with another Yuri, who is ahead of me in correspondence with you. You probably had a conversation with him about the failure of the frequency response. To clarify, I added the letter “B”. I have a question: is it possible to add a resistor in series, otherwise I don’t have a PEV type for 10 ohms? And the second question is whether the filter should be upgraded in the future according to your recommended article, Radio 1985 No. 4 (your typo is not for 1984). I really liked it - the cutoff limit of the low-frequency driver is lowered. Of course, I will carry out the modernization step by step, comparing it with another column (I put music of different genres and the balance alternately left and right). And a question for the future - on Arcturus 004 there are a couple of second outputs for the AC - I have never used it. How would you recommend using it? Maybe you can make a separate entrance for the same 25AC309? Sincerely, Yuri.B.
• Author / 03.27.2018 - 19:59
  The 25AC-309 filter for the midrange head has a cutoff frequency of only the low frequency. There are no restrictions on the upper frequency range. What do you want to improve? The sensitivity of the 6GDV-4-8 head is two times higher (3 dB) than that of the 5GDV-1. Therefore, the signal must be attenuated by half. To do this, resistor R3 (5.1 Ohm) is replaced with a resistor with a nominal value of 12 Ohms or close to it. If your circuit has a resistor R3 of 3.3 Ohms, then replace it with 10 Ohms. That's all the modification. Make sure the polarity of the heads is connected. You wrote about a dip at 3000 Hz. If you measure two heads at once, midrange and high-frequency, then failure occurs when they are connected incorrectly. The polarity of the RF head connection should be changed.
• Yuri / 03.27.2018 - 17:40
  Vladimir - thank you so much! Tell me about upgrading the filter. Should the midrange cutoff band be increased? What changes need to be made based on the parts of the old filter is desirable. And how to bind a new tweeter? Maybe it’s convenient for you to send it to my email. -I will write. Regards, Yuri.

Here are located scheme,detailed description, options Acoustic speakers speakers Radiotehnika class S90 (S90, S90B, S90D, S90F)

High-quality acoustics from Soviet times, after minor modifications and restoration, we can confidently say that they 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.

S-90 first model

In the speaker system
S-90 There are 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.

S-90

Nameplate power 90 W
Rated power 35 W
Nominal electrical resistance 4 ohms
Frequency range 31.5-20000 Hz
Nominal sound pressure 1.2 Pa
Overall dimensions of speakers 360x710x285 mm
Speaker weight no more than 30 kg

Schematic diagram of S90

IN AC There is an indication of speaker head overload. Regulators located on the front panel AC, make it possible to smoothly adjust the sound pressure level of the high-frequency and mid-frequency loudspeaker heads in 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. The rest of the design" 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).

Passport specifications S-90D

Nameplate electrical power " S-90D"/"S100-D" not less than 90 W 100 W
Rated electrical power 35 W
Nominal electrical resistance 8 ohms
The range of reproduced frequencies is no longer 25-25000 Hz
Characteristic sensitivity in the frequency range 100-8000 Hz, at a power of 1 W, not less than 89 dB
Overall dimensions of speakers 360x710x286 mm
Speaker weight no more than 23 kg

The figure below shows the principle scheme speakers S90D.

Schematic diagram of S90D

Speakers S90 diagram, description.