27122

Modernization of S-90 speakers by replacing standard cases with a labyrinthine design of bass dynamics

Upgrade of the labyrinth design S-90 stuffing squares with cotton wool and sticking on the inner surface of a woolen blanket
At first, only the frontal knees of the labyrinth were pasted over with wool, then the side surfaces too
Ready-made maze S-90 with wool-pasted inner surfaces

Alteration of the most famous speakers of the USSR Radio engineering S-90

Alexander Rogozhin came up with the know-how of how to translate the S-90 Radiotechnics speakers, most known to most Russian-speaking people, into labyrinthine buildings. The article is devoted to the most widespread acoustics of the Soviet period that was considered the standard for more than 20 years, which in its first generation was called 35AS-1. And Rogozhin proposes to make speakers with the name "Cheap, Loud and Super Bass" out of 35AS-1 (Radio Engineering S-90)!

Ode to speakers Radio engineering S-90 (35AS-1)

There is no such person who speaks Russian, Ukrainian, Belarusian, who at least once in his life did not hear the famous Soviet speakers Radiotechnika S-90, or did not have one of their modifications made in over 30 years. You can think whatever about their sound, appearance, rubber speakers, but in fact these are the MOST common "People's" speakers in the vastness of the former USSR. They still work in tens of thousands in the systems of music lovers who feel sorry for throwing them away. in comparison with the branded "remake" they play very, very worthy.

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

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

And yet we all love to listen to music, we all have good mood when you want to turn 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 are impossible to listen to without bass. without it, the lion's share of important musical information disappears. The soul asks OOUH! And the low frequencies are actually quite thin thing, in order to adequately sound and make an impression, they ask for large speakers, enclosures and powers. But even with all this (in large speakers like S-90), the bass often turns out to be buzzing, drawn out and indistinct, and does not give us the "buzz" that it should give us. We quickly get tired of such a bass and begin to turn the tone control knobs or switch the equalizer modes on the receiver. And instead of getting pleasure - to get irritated and think about the imperfection of this mortal world ... Almost all music lovers and owners of this acoustics, in particular, have found themselves in such a situation more than once.

Bass problems S-90

The reason that over the past 30 years the owners of the S-90 radio engineering acoustics and its numerous modifications are not satisfied with its sound and somehow they are trying to cope with this problem lies in several reasons. The main problem of the S-90 speakers, confirmed by repeated research by specialists, is a mistake made in the design of the low-frequency design of the 30GD-2 speaker. Having gone into the series, the error led to the fact that the potential of high-quality low frequency reproduction, originally laid down in the S-90 Radio Engineering model and its modifications, is not realized even by 20-30% of the possible ones.

A huge number of S-90 owners, almost from the moment they appeared on sale in the 80s and up to today trying to improve the low frequencies of these speakers by magic with filters, reworking the pipes of the bass reflexes, strengthening the native housings and filling them with anything.

Dear music lovers! I urge you to stop doing nonsense, because it is absolutely useless ... The S-90 speakers from the factory have a body 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 trim it at least with the root of rare rocks and glue it over with porous rubber on all sides - it will NOT work correctly anyway.

That is, the question of drastically improving the performance of these speakers at low frequencies, it is regrettable as it may be - the question of replacing the case, rises to its full height.

The task is somewhat complicated by the fact that over 30 years a huge number of modifications of 35AS-1 speakers with low-frequency speakers 30GD2 / 75GDN1-4 (8), having a large scatter of parameters, have been produced. In the new enclosures, this problem has been largely addressed and allows speakers from the earliest to the latest to feel right. The tuning of the new enclosures is "stretched" and allows NOT to engage in the selection of subwoofers on purpose.

Mid-frequency problemsS-90

Almost all owners of the s-90 speakers note disgusting overtones and a large uneven response at midrange frequencies, which become especially noticeable at medium and high volumes. All grandiose projects for reworking filters by installing expensive imported capacitors in them, replacing wires, resistors, etc. as well as the options for gluing half of a tennis ball, etc. to the midrange cone. fail.

The main reason for the unsatisfactory sounding at medium frequencies is not the 15GD-11 speaker at all, but its acoustic design. This "glass", covering the midrange head from behind, has a scanty 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 interior design. When replacing the casing of the s90 speakers with the correct one from the point of design of the woofer, the mid-range speaker should also be designed accordingly.

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

What can you get

As a result, the updated S-90 speakers will sound radically different not only at low, but also at mid frequencies. On the Internet there are a large number of attempts to alter the S-90 speakers in order to "deceive everyone" and turn them into studio monitors. Attempts concern everything, just not replacing the main "weak point" - the case, and most often they turn out to be a failure. While keeping the S-90 speaker enclosures unchanged, in order 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 intact. Their value is in the minimum budget and no matter how clever you may be, proven by decades of operation in the most severe conditions - performance.

In these columns there is something that can be improved in principle, this is to "get the maximum possible" from its speakers. To do this, you need to make an acoustically correct case for the original set of speakers and filters. As a result, you can reach a fundamentally new level of sound quality of these speakers without spoiling anything.

As a bonus, the old cases can not be thrown away and, if necessary, the "stock" S-90s can be assembled back and sold to any lover of authentic speakers made in the USSR.

Problems of native boxesS-90

• The wrong volume of low-frequency design does not give the required level of pressure on the bass;
• Suboptimal bass reflex tuning frequency leads to uneven bass response and poor bass quality;
• The type of low-frequency design "bass reflex" in combination with a "tight" speaker on a rubber suspension leads to an extended and monotonous "hum" at low frequencies, instead of a clear percussive bass;
• Phase-inverted acoustic design leads to significant unevenness of sound pressure at low frequencies in the room, and makes demands on obtaining high power from the amplifier;
• Weak walls of the S-90 speaker boxes lead to a loss of efficiency at low frequencies and give noticeable overtones when working at high volumes;
• Poor sealing of the boxes does not allow even the low-frequency design that the S-90 speakers in the stock version have;
• The extremely small volume of the cap of the mid-frequency head 15GD11 (20GDS-) leads to a "jamming" of the mid-frequency dynamics;
• Suboptimal damping of a small boxing midrange leads to noticeable overtones and "nasal" 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 furniture at high volume and, as a result, to a deterioration in the sound of low frequencies;
• The “low-profile” shape of the speaker enclosures requires them to be mounted on specialized speaker stands, which ultimately increases the cost of the system. Placing 35AC-1 speakers on the floor leads to a lack of high frequencies and an incorrect scene.

Benefits of new enclosures

• 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 Q-factor of the quarter-wave resonator give a wide bandwidth and an optimal level of low frequencies;
• The highest rigidity of the box gives the highest possible efficiency, clean, resilient and biting sound at low frequencies;
• Rigid boxing of a large volume of the midrange head gives a lively and open mids and clear vocals;
• The location of the midrange and tweeters on the front panel with respect to the distances to the walls of the cabinet according to the principle of the "golden ratio" reduces diffraction phenomena on vocals and high frequencies and makes the sound much more comfortable;
• With the new enclosures, the acoustics is transformed into a classic floor-standing design with optimally positioned midrange and tweeter speakers;
• The speakers have narrower and taller front bezels than the standard S-90 and do not require any stands. The appearance of the speakers is improved many times over.

Music surrounds us everywhere: at home, in the office, in the car, in the gym, and everyone has their own musical preferences - from classical to rock. At the same time, you want to fill the space around you with high-quality sound and enjoy your favorite tunes to the fullest. Acoustic systems and speakers from various manufacturers help us in this.

Shape your preferences

The main thing in choosing sound equipment is the purpose of its use. This refers to the size of the room and the power you can afford when listening to music. To optimize the process, we recommend acoustics with a small power reserve. The main thing here is not to overdo it, since 80 - 100 W per channel will be enough for a room up to 20 square meters. The following criteria will allow you to make your choice:

• type of placement of the speaker system (floor-standing, hanging, portable, built-in);
• the number of playback channels;
• type of control (via remote control or manual setting);
• preferred material for speaker enclosures and subwoofer;
• frequency ranges;
• dimensions, weight and other requirements.

How to make the right choice

Considering the variety of rather expensive models offered by the modern market, buying a stereo system of an eminent brand may seem like a rather expensive undertaking to you. You can be helped out by music speakers in the budget segment, many models of which are offered by the Aport website catalog. As practice shows, for modern man not only sound performance is very important, but also design, portability and usability. The decisive role here is played by the type of power supply: from batteries, USB, its own outlet to the network. Another important criterion in choosing music speakers is the price. Many online stores offer a ton of options - sometimes the same product, but with a different price tag. The filter system and the price comparison functionality of the Aport website will help you choose best speakers at a low price and not be disappointed when listening to your favorite songs.

1. Small enclosure volume for woofer. The consequence is the bubbling of low frequencies.
2. The phase inverter is designed for a frequency of 20 Hz. Consequence - large distortion of low frequencies.
3. Useless midrange speaker. Consequences - disgusting midrange, overtones.
4. Low frequency resonance of the tweeter. Consequences - "quacking", hissing.
5. The filter is designed taking into account the previous disadvantages. Consequence - when modifying any node, 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

Drinking beer, we come to three truths. There are three ways:

1. Lightweight and efficient.
2. Medium difficulty. More shamanism and snobbery. Some sound improvements over item 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, make sure that the speakers are correctly phased. If you have not experienced this yourself - invite a specialist - electronics!
2. Alteration of the speaker 15 GD - 11A is an irreversible process. In case of inaccuracy, the speaker has one way - to the trash can, and you have another - to the market.

The first way. Lightweight and efficient.

1. Mids are the main focus. By altering the speaker, we will achieve its operation in the piston mode, increase the upper cutoff frequency, remove overtones, increase the sensitivity, improve directivity, and damp.
2. Let's translate the column into the range from 31.5 Hz, instead of 20 Hz. Mumble less.
3. Let's set the resonance of the high-frequency head.
4. Calm down the overtones of the body

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

Let's get down to creativity. We saw the ball in half along the seam. The seam is visible in the light. It is made with an overlap and is 1 - 2 mm wide. It is necessary to cut in the middle of the seam. I sawed with the blade of the Neva, having previously made notches on it with a sharpening bar. After sawing, align the cutting line on sandpaper, and sand the outer surface of the ball with fine sandpaper. If there are large nodules inside in the seam area, then they must also be removed. When working, the ball must be fixed with plasticine on a Mars battery (a case from photographic film, jars of food for fish, etc., according to the imagination) at three points. It's enough. Plasticine is removed by sweat or a dry cloth or wiping with gasoline. After the surface of the ball has been processed, it must not be touched by hands. Rub pencil leads on sandpaper.

Dilute epoxy with double the amount of hardener. Cover the surface of the ball with the thinnest layer. If necessary, remove excess glue with newsprint. Sprinkle with graphite, shake off the excess. It is necessary to ensure that the white plastic of the ball does not shine through the graphite. If it shows through, then the epoxy layer was small. I must add. After everything has worked out, we leave it to harden.

Putting together 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 fit a choke under it. In order not to clog your head with unnecessary formulas, the simplest thing is that the product of the capacitance of the capacitor in microfarads by the inductance of the choke in mH should be equal to 2.82. Suppose 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 coil inductance is 2.82: 6.6 = 0.43 mH, (the winding contains 150 turns of wire PEV-1 0.8 wound on a frame with a diameter of 22 and a length of 22 mm with a cheek diameter of 44 mm). Based on 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 fasten the capacitor and the choke on a piece of fiberboard and solder one output of the coil to the output of the capacitor. We solder wires 40-50 cm long to the free terminals.

We disassemble the column. We remove the low-frequency speaker, mid-range, take out the glass from it, remove the high-frequency speaker, remove the decorative cover, remove the phase inverter (on some speakers, the filter will have to be unscrewed). 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 midrange speaker head with hard glue. Care must be taken to ensure that there is no unsticked lye 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. We leave to dry.

We screw the homemade filter onto the back of the speaker (inside) opposite the tweeter. We solder the wires from the filter to the output of the tweeter. Which where - does not matter. We remove the connectors from the back of the speakers and solder the wire from the amplifier directly to the filter. Saw off the phase inverter pipe with a hacksaw for metal 10 cm along the middle line. We wrap the phase inverter pipe and the glass of the mid-range speaker with a layer of gauze and bandage. It is necessary to check whether they will enter their nests after this procedure. If not included, then reduce the layer of cotton wool with gauze. We check if there is cotton wool and gauze in the glass. Add if not enough to complete. Damping the mid-range speakers. To do this, we additionally tighten their diffuser holders with foam rubber rings made from blanks 10x27x355 mm. the ends of which are glued with "Moment" glue butt-to-toe. We glue 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 fix the bandage with threads. We collect the column. We coat all the perimeters of all speakers with plasticine. It is not worth putting on protective nets, but only on the condition that there are no small children, the wife does not come in with a mop or vacuum cleaner, and that the speakers will not be transported. We turn on the speakers. We do not know the right. We call friends. Please drive up with your favorite recordings. Let's listen. We soothe our friends with beer. With a sneer, we notice how the bucks spent on the purchase of foreign trash would be useful to them.

The second way. Medium difficulty.

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

1. Let's improve the properties of the body and kill the overtones and "barrel"
2. Get the best signal flow
3. Enclosure sealing. Removing the influence of the body

So let's go. Strengthen the back wall of the case by placing two strips with a cross section of 3x2cm. vertically in full length at a distance of 15-20 cm from each other symmetrically, and by attaching them with screws to the back wall. Pre-treat the attachment point with epoxy. It is necessary to take into account the possibility of installing a phase inverter later. Between the rear and front walls, we install a spacer bar 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 of the "Bison" type or sanitary silicone putties. We glue the entire body inside with felt (batting, padding polyester, etc.). Thicker than 1.5 cm is not worth it, so as not to greatly reduce the internal volume of the case.

We reject all proposals to change 15 GD - 11A to 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 change the filter a lot. 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 are specified. When using 6 GDSH - 5 - 4, you will also have to put additional resistance in the circuit of this head at 4 Ohm. Also appearance column changes. Well, if you really want to, then you can. Further. Removing the tone switches. Remove unnecessary resistors R (1, 2, 4, 5, 7, 8, 9, 11, 12). We replace the wires on the installation of the filter with a copper wire with a diameter of 1.2 mm. We replace the wires going from the speakers to the filter, with more track ones. On the low-frequency speaker - stranded - with a cross section of 2.5 - 3 mm2, for the mid-range - 2.5 mm2. For high-frequency - 2 mm square. - single core. All wires are soldered directly to the filter instead of passing through the previous speakers. The filter is installed at the bottom of the column. All wires are placed under the felt layer. On the side walls.

The filter controls are removable. We make wooden (chipboard, plywood) plugs in their place according to the thickness of the body. We pour them into epoxy and grind them. We cover the front panel with self-adhesive wood-like film to match the speaker veneer. We install the speakers. Low-frequency and mid-frequency through rubber grommets. Rubber from window insulation, thin rubber medical hoses, silicone hoses (worse) will do. We process 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 are simply bastard. Moving away all sorts of "Pioner", "Technics", JAMO and ...

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

It is 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 repair and assemble at home - of course, this is not all, but there is a way out - to go to the workshop and ask to try on what you need to take with you filters, heads, etc. If they ask for a fee for this, it is purely symbolic. You can even order a filter. This, of course, will be more expensive. We take 35AS-212 as a basis with dimensions 710x360x285. It is desirable to have a plywood case, a woofer with a rubber surround, a tweeter with a glass cloth dome. We disassemble everything. We no longer need a mid-range speaker. The enclosure needs to be extended for the rubber-suspended woofer up 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 panel from the case, so that it can then be used for the matrix for speaker holes in the newly manufactured 100-liter case. From the remains of the buildings, good boxes are obtained for potatoes and a stamp in the cellar.
2. You can try to build on the old building.

In the first case, you need to focus on the dimensions - 1100x360x350 and manufacturing 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 fitted walls and lids made of double 10-ply plywood with external dimensions - 380x360x285. In the bottom of the column and in the lid of the box, cut out the same holes approximately 270x210. We glue the box inside with felt. After assembly, it will be unrealistic 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 sweat. To fall asleep a little - 10 kilograms of shot will not hurt, we throw a gauze bag with cotton on top. Pre-spill the compound with epoxy with a normal hardener content. Paste the junction with felt. The rest of the body movements with the body, as in paths 1 and 2. Take the mid-frequency head 30 GDS-1. You just need to check them - there is a lot of marriage. Purely mechanical properties. Further. We measure the f resonance of all speakers. You can sign with a felt-tip pen directly on the magnets so as not to get confused and not measure everything again.

It would be nice if the resonance frequency of the paired speakers did not differ much. If the speaker emits extraneous sounds at any of the sound frequencies, then it must either be cleaned or changed if cleaning failed to achieve normal operation. We calculate and make filters for our case. The less inductances, the better. We continue to work with the body. Remove excess resin at the junction. We grind it down. We make two wooden filter boxes. We will fix them on the outside of the back wall. We will solder the wires from the amplifier directly to the filters. And we will pull the wires to the speakers through the speaker connectors. All wires are branded audiophile. Choose the price category yourself. It's just very expensive to take - it makes no sense. It is better to remake the phase inverter for a frequency of 31.5 - 40 Hz. If the dome of the high-frequency head is made of lavsan, then, after removing the cross, it is necessary to coat the suspension and the outer third of the dome with perchlorovinyl. We glue the entire body with self-adhesive foil. 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 - 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 radiators. - M .; Radio and communication. 1985.
4. Zhbanov V. Mechanical damping of diffusers. - Radio, 1988, No. 5, p. 41-43.
5. Maslov A. Once again about the alteration 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 modernization of acoustic systems. Bulletin A.R.F. No. 6 "2000

11-01-2009

Modification of acoustic systems Radiotehnika 35АС-012 (S-90)

Radiotehnika 35AS-012, Radiotehnika S-90, Radiotekhnika 35AS-012, Radiotekhnika S-90

At the moment, I am the proud owner of Radiotehnika S-90 speakers.

Consideration of acoustics in a normal state

To begin with, you should specify the full name of the acoustics - 35AC-012. From their number it immediately becomes clear that we are dealing with acoustics of the highest class, by Soviet standards, that is, with acoustics having very high characteristics. It should be noted right away that by Soviet standards it was not the best acoustics, but an ordinary private workhorse... There were acoustics that had a more balanced sound, for example, the same Cleavers / Corvettes 35AC-008.

But as they say, we have what we have. Let's go back a bit to the moment of purchasing them. I took them from my friend for $ 50, when I came to him, when I saw the decorative grilles protecting the sound-emitting heads, I wanted to cry, they were dented and, moreover, very severely (mostly the treble and mid-range speaker grilles were damaged). But this did not scare me, since what was sold in our market cost at least $ 100, and the quality of the speakers deserved no more than 3, and in these speakers the speakers looked at 5. In general, I took these speakers to my home. When connected to an amplifier, the sound was pretty decent. But nevertheless, two shortcomings should be noted, 1 of which is inherent in all 35AC-012, and as it turned out, all of its 35AC clones, to one degree or another.

The first of the shortcomings that simply killed me on the spot was an incomprehensible sound when the bass driver was working, very similar to the fact that something was stuck to the speaker behind, and now something vibrates, as it turned out later it was a drop of solder that stuck to diffuser on the back. The second drawback was precisely the dynamics of the mid-frequency 15GD-11A - according to the old standard and 20GDS-1-8 according to the new (these speakers came in a large number of modifications for this reason, which is extremely difficult to track with you). And again, a small digression, in which I will say that the differences in the standards are in the designation of power, that is, according to the old standard, the nominal power of the speaker was indicated, and according to the new standard, the passport power is indicated (from the sound engineering course:

1. The nominal power of the speaker is such a power of the speaker, when summed up, it works with harmonic distortion levels not exceeding the permissible
2. Passport power (often also called noise power): this is the level of power supplied to the speaker, at which the level of harmonic distortion is equal to ten times the level at the rated power).

An additional division into the frequency ranges of the heads was also introduced, which was now indicated in the name of the speaker, in particular, this is the third letter.

So the disadvantage of this speaker is that it often begins to resonate at high volume and thereby spoil the sound picture, and as you know, the mid-range speaker is crucial in the formation of the sound picture.

Let us now consider in order all the speakers that we have in stock:

1)Low-frequency - 30GD2, aka 75GDN-1-4 (8):

Purpose - use in closed and phase-inverted remote acoustic systems of household radio equipment of the highest complexity group as a low-frequency link when working indoors. The loudspeaker head is of an electrodynamic type, low frequency, round, with an unshielded magnetic circuit. The diffuser holder is made of die-cast aluminum alloy. The cone diffuser is made of impregnated paper pulp. Suspension - toroidal shape - made of rubber. The centering washer is made of impregnated fabric.

I also want to add that the speakers have a relatively heavy dome and a rubber suspension is used, which spoils the quality of the bass, it becomes more solid and boomy than in speakers with a lighter mass of the moving part and a foam suspension. But it should be borne in mind that the bass is influenced not only by the design, but also by the acoustic design itself, for this reason, these troubles can be slightly eliminated and the speaker will play with dignity. On the other hand, due to the rubber suspension, the speaker turned out to be very reliable and practically indestructible, and the foam suspension soon disintegrates due to the presence of sulfur in the air and the speaker needs to be repaired.

Purpose - use in closed and phase-inverted remote acoustic systems of household radio equipment of the 1st and 2nd groups of complexity as a mid-frequency link when working indoors. The loudspeaker head is of an electrodynamic type, mid-range, round, with an unshielded magnetic circuit. The diffuser holder is made of die-cast aluminum alloy. The conical diffuser and the spherical cap are made of impregnated paper pulp. The toroidal suspension is made of polyurethane foam. The centering washer is made of impregnated fabric.

Here is a photo of this miracle of technology:

It is worth saying that at a good volume, it distorts the sound decently, but as practice has shown this problem very easy to solve and, moreover, very simple.

Purpose - use in closed acoustic systems of household radio equipment of the highest complexity group as a high-frequency link when working indoors. The loudspeaker head is of an electrodynamic type, high frequency, round, with an unshielded magnetic circuit. The mounting flange and acoustic lens are made of plastic. The domed diaphragm with suspension is made on the basis of polyethylene terephthalate.

In general, they sound good only here the filter settings are close to resonant frequencies.

On closer examination of the acoustics (especially from the inside), you begin to be horrified by the build quality, for this reason, we will begin to refine it. We will refine it according to the simplest possible scheme, without interfering with the filters, since there is nothing to do there without specialized equipment. Who will be interested in the acoustics diagram:

Modification 35АС-012

I will describe in order all the stages of improvement that my columns went through:
1. Disassembly:

• First of all, we take them to a secluded place (meaning a room) in which our experimental subjects will not be available to children (if any) and other family members. We put the speaker system on our back and begin to disassemble it.
• Now we remove the decorative covers from all the speakers and set them aside.

Here they are:

Then we take out the speakers. ATTENTION when unscrewing the bass speaker (the tweeter and midrange speaker are attached with the same screws as the decorative cover, and the woofer is attached separately from the cover), be extremely careful, because if the screwdriver comes off, you will disfigure it. Then we solder the wires connecting the filter and speakers with a soldering iron, and boldly hide the speakers in a secluded place.

• We remove the bass reflex cover and take out the phase inverter itself, and this must be done as carefully as possible, since we work with plastic, and it can easily break. Then we hide these details in a secluded place.
• Now we take on the regulator / regulators of the HF / MF links. To dismantle them, it is necessary to remove the decorative plug in the center of the regulator, then unscrew the opened screw and remove the regulator knob. After that, carefully pry the remaining plastic lining with two chisels and carefully remove it, then unscrew the 4 screws that secure the attenuator itself and now it can be pushed out into the case. We push it out and unsolder it from the filter. We put it aside, in the future it will be necessary to conjure a little over it. By the way, the junction of the attenuator case and the column case is abundantly covered with a sealing viscous substance, I personally used it again when I put it back in place, but you can use a sealant or plasticine.
• We take out the bags of cotton wool, which, in theory, lie in your speaker system and put it aside.
• We dismantle the panel with filters, it is screwed to the body with screws, after having previously unsoldered the wires from the outlet on the back of the speaker system. We put it aside, since a lot of time will be spent with them at work.
• Finally, remove the panel with terminals from back cover AU and put it off.

It seems that a lot of work has been done, but in fact it is just a drop in the ocean. More interesting and laborious work lies ahead.

2. Restoration of appearance:

For this purpose, we take the previously removed grilles and pads from the speakers, level them, carefully sand them, degrease and paint in several layers with automotive paint (which is in cans) several times and leave to dry. Immediately I will make a reservation that I restored the grilles only for the reason that I have a small child who can damage the speakers, otherwise the simplest solution would be to abandon the grilles as such, since they bring only disadvantages to the sound, then think for yourself.

3. Modification of the speaker case:

Here, in fact, everything is very simple, and it is carried out in several stages:

• The body can be reinforced if desired. What will it give us? Clearer and more even bass, since the cabinet panels will vibrate less and, accordingly, will introduce less noise into the bass component of the sound. How to do it? Here it is purely everyone's business, since there are as many decisions as there are people. In general, everything consists in installing spacers, installing additional corners at the joints of the walls of the speaker system, installing stiffeners on the walls of the speaker. Personally, I limited myself to pasting in additional corners at the joints. You can also glue all joints tightly. Unfortunately, I can’t show the photo as the whole acoustic system already damped with foam rubber.
• Sealing all joints and seams. It is carried out very simply with the help of various materials. For example, I used a plumbing sealant. The procedure is simple: cover the joints with sealant and gently smear it with your finger, thereby tightly sealing up any cracks.
• In a hardware store we buy foam rubber with a thickness of 10 mm (I personally chose this thickness, do not take too large as you will strangle the body) and glue it to all walls except the front with glue. Thus, we dampen the body, thereby increasing its virtual volume.

To do this, we buy terminal blocks with gilded universal connectors in the store. Since the S-90 has a large terminal block by itself, and the new ones are small, we dismantle the connectors from the terminal blocks and install them on the case from the S-90 terminal block. Then we lubricate the installation place on the sealant (do not regret it, then wipe off the excess) and put it all in place, tighten the screws. Here is a photo of what you should get:

5. We proceed to the alteration and installation of the filter in place:

• First of all, carefully consider the filter, pay attention to the fastening of the parts, since often the inductors were fastened with metal screws, which immediately knocks down the filter setting.
• If there were problems in the fasteners, complete it to the end by excluding the metal parts from the fasteners. There are also cases of assembling the filter on a metal plate, then transfer the filter to the plywood panel.
• We take a leaf, a pen in our hands and carefully redraw all the elements of the circuit, restoring the filter circuit itself, so to speak, because the parameters of the speakers were walking and for this reason the factory could change the filter circuit. By the way, we exclude the attenuator from the circuit, it just spoils the sound.
• Now we take a soldering iron in our hands (preferably 100 watts) and disassemble the filter, or rather, we simply remove all the jumpers that were from the factory.
• Now we are assembling the filter, instead of jumpers, we will now use an oxygen-free copper cable with a cross section of 4 mm 2, the cable can be bought at any car audio store. It should also be noted that you should not take a very expensive cable, since the changes in sound quality will be insignificant, but the costs are simply colossal.
• After assembling the filter, we solder the wires that will go to the speakers based on: for the low-frequency link 4 mm 2, for the mid-range link 2.5 mm 2, for the high-frequency link 2 mm 2.
• We put the filter in place, after which we solder the terminal blocks to it (observe the polarity, otherwise you will lose the sound picture).
• The very last step is routing the speaker wires, securing them, and covering the filter with foam.

You will get something similar to these photos:

6. Installing the attenuator:

• We remove all resistance from it.
• We put it in place.
• We seal carefully.
• Additionally, we close it with foam rubber (I only closed it on the front wall)
• We install all the decorative panels to the end.

7. Bass reflex installation:

Everything is simple here, we put it back on the sealant, we carefully monitor it so that it is not clamped anywhere with foam rubber, as this will knock its setting.

8. Reinstall the bass reflex cover:

We put it in the same way as we removed it, just put it on the sealant and on new screws, since the panel itself often rattles on bass. Seal the joint between the panel and the bass reflex well.

9. We proceed to install the speaker drivers in place:

• A) Install the RF head:

1) We remove that parody of the seal that stands on it (behind it, some kind of gum or cardboard).
2) Cut out a new seal, a mouse pad is perfect, in particular a black porous base.
3) Solder the wires to the speaker and install it in place.
4) Put in place the decorative cover (optional grille) and tighten it tightly with the screws.

• B) Install the midrange head:

1) We make a cylinder of foam rubber, of such a size that our box would fit into it. We put this cylinder inside the column and pass a cable through it, which we bring out.

2) We pass the wire through the box (most likely it will be necessary to widen the hole), after which we put the box in place, adjust the length of the wire and seal the hole into which the wire is passed.
3) We solder the wires to the speaker.
4) Now the crucial stage is the damping of the mid-frequency head. To do this, we sew a cylinder of foam rubber, such that it fits tightly on the speaker frame and closes all the windows.

5) We fill the box with cotton wool, having previously fluffed it up.
6) Put the dynamic head, grill (optional) and frame in place and tighten.

1) First, put back the bags of cotton that were removed during the disassembly of the speakers. We solder the wires to the head. I tied the wires that are soldered to the head to the frame so that they do not hit the diffuser, because there is a possibility that when you put the speaker in place, the wires will bend and fall into the window of the diffuser holder.

2) We make a pad of porous material, for example, you can
apply a window seal and carefully put the speaker in place.
3) We tighten the mounting screws. Great effort do not apply, then the speaker will be spring-loaded by the gasket and this will reduce the vibration energy transmitted to the cabinet.
4) We put in place the lattice (optional) and the decorative overlay. If you did install the grill, then I advise you to cut out small triangles from the foam rubber and put them on the speaker in the place of its attachment, this will exclude the vibrations of the grill, and therefore will remove overtones at high volume.

I came up with this solution a long time ago, see the photos for more details:

Conclusion:

After revision, all the listeners (there were few of them, about five people, but I asked for the most honest information from them) noted softer and softer basses, a much cleaner mids, the top remained practically unchanged (it seemed to me that they became a little cleaner). Also, the acoustics began to quietly take higher volumes.

In conclusion, I would like to say that the proposed method is the cheapest, simplest and most affordable. All components, of course, can still be modified or changed several times. For example, instead of foam rubber, you can use felt (natural), this, in theory, will give better results than foam rubber, it is also good to use vibromastics. Many people advise replacing the 15GD-11A with a 5GDSh broadband, for me this is a bad idea, but this is everyone's business. 10GD-35 - it is advised to treat with a notch filter, 15GD-11A should be modified based on the halves of a tennis ball (by the way, the idea is quite interesting, I did not do it myself, since I do not have such speakers in stock).

Register now.