DIY oval speaker repair

The current state of the market with loudspeaker prices makes speaker repair virtually unnecessary, but if there are difficulties in purchasing a new speaker instead of a damaged or damaged one, then it makes sense to try to restore the damaged loudspeaker with your own hands. I got a few coaxial speaker systems from various cars. Unfortunately, 2/3 of the speakers produce a distorted signal during playback, and the rest simply do not work. Below will be presented material only on the restoration of "littered" coaxial-type car speakers for use in the future in the design or installation in multi-way stationary speaker systems. Before starting work, we will carry out diagnostics speaker states.

1. Check for "trash". Coaxial speakers are not fully protected from foreign objects falling into the magnetic gap, this is especially dangerous for old cars covered with rust or cars that have undergone body repairs. Checking is simple - gently with your fingers moving diffuser inside the magnetic system, if at the same time extraneous sounds are clearly audible: rustles, crackles, rattling, then this means that metal debris may have got into the magnetic gap.

2. We take a tester and in ohmmeter mode we check the resistance of the coil. If there is resistance, then this is our case. If there is no resistance, then it makes sense to check for an open circuit thick flexible copper conductors from the speaker terminals to the diffuser. If there is no break, then most likely there is a break in the speaker coil and this case of self-repair is not considered in this article. Instructions for self-repair are given below.

1. We unsolder the flexible leads of the coil from the contact lugs of the speaker connection and the contact lugs of the coaxial speaker.

2. Remove the coaxial speakers. Repair of the speaker system is not provided by the manufacturer and coaxial speakers are installed tightly... The column with reinforced tweeters was removed by drilling an aluminum rivet. We work carefully, the main thing is not to tear or damage anything.

3. On the forums for repairing speakers, there are ways to dismantle the diffuser and centering washer. I also went along this path. We carry out the work in the open air in the absence of open fire sources! After spending 100 ml of acetone, it was not possible to peel off the diffuser and the washer. The solvent evaporated quickly without softening the glue line. In order to save time and solvent, a cord made of cotton cloth was placed in place of gluing and moistened with acetone; if necessary, moistening as it evaporated continued until the glue softened. After softening with a thin screwdriver, he forged the edge of the centering washer and lifted it over the gluing point. With the corrugation of the diffuser made of thin rubber, you need to be more careful and delicate so as not to damage the rubber.

Pouring solvent onto the corrugation

4. Remove the diffuser. From debris that got inside the magnetic system, damage-scuffing of the insulation of the speaker coil is noticeable. It is useful under a magnifying glass to see the degree of damage for the presence of short-circuited turns (scratches to a depth of more than 40% of the coil wire diameter), if there is a suspicion of short-circuited turns, then it is better to reject the speaker. Using a damp cloth, I cleaned the diffuser, centering washer and coil inside and outside from dirt. Cleaning should be done carefully so as not to damage the coil.

There are scratches on the coil

5.The gap in the magnetic system is a sad sight. Strong magnet holds fine metal debris and dust firmly. I tried to clean it mechanically, but the small size of the gap and its curvature did not allow successfully removing debris. Decided to use a strong blast of air from an air compressor - it was not possible to clear the gap! Another remedy had to be used - a high-pressure jet of water from a car wash. The result is that I am all wet, but the gap is 100% cleaned, and at the same time the whole frame of the frame shone like new. I tried to do it carefully, since the pressure of the water jet is very high and I suppose with special zeal it is possible to destroy the gluing of the speaker magnet. To prevent rusting, you must immediately dry the frame and magnet. After drying, it is useful to check the cleanliness of the gap under a magnifying glass. And as experience has shown, it is good to seal the gap with tape to protect it from accidental metal debris.

1. After cleaning and drying the speaker components, we assemble the structure. It's important not to rush. The goal is to position the coil in the magnet system exactly in the center and to ensure there is clearance and no touching the coil. From a strip of A4 format office paper 10 cm wide and about 18 cm long, we roll up the cylinder and insert it into the diffuser coil. The cylinder must fit snugly against the spool and not have any protrusions or bulges inside.
2. Let's try to insert such a structure into the magnetic system. Do not hurry! Better to practice a few times. The cylinder should descend to the full depth of the magnetic gap and the coil should hardly move over the inserted cylinder. If the coil moves along the cylinder with great effort, then it is necessary to shorten the length of the paper strip, and if the coil moves freely, then it is necessary to increase the length of the paper strip.

Insert the cylinder into the gap

The coil runs tightly in the cylinder

The reel is centered

3. Holding the cylinder in the lower position, raise the diffuser and grease the area for gluing the centering washer with glue of the "Moment" type. We orient the washer according to the leads of the coil conductors and speaker terminals, as well as along the cutouts in the corrugation of the diffuser. We glue the centering washer.

4. We glue the corrugation of the diffuser.

5. After the glue has dried, we solder the coil conductors to the terminals.

6. Carefully remove the paper cylinder. Checking the diffuser travel. If everything is done correctly, then there should be no extraneous sounds.

7. To close the magnetic system from the ingress of debris, I sealed the coil hole on the side of the diffuser with black spunbond, and on the side of the magnet with tape.

Glue the centering washer

Sealing the diffuser hole

Seal the hole with tape

8. Finally, we check the result of the work by connecting the speaker to the sound source.

Using this technique, several speakers were independently restored for installation in stationary speaker systems and radio receivers to replace old or torn speakers.

I tried to collect this way. It didn't always work out.
I did the assembly differently. After gluing the corrugation of the diffuser and the centering washer, until the glue has dried, I connected the dynamic head to a 6.3 volt transformer through a low-resistance variable wire resistor.
It was enough to slightly stir the diffuser.
In this case, the diffuser itself is centered. The noises disappeared immediately. In this position, he dried.

The disadvantage of this method: 50Hz is still hard to withstand for a long time.

The constant must be connected!

Professionals - a must, but amateurs can do so!

Are the speakers wheezing? Do not rush to throw them away, getting rid of the wheezing of the speakers is possible and not so difficult. Speaker wheezing, a fairly common phenomenon, is most often found in broadband acoustics, due to dust and all kinds of debris trapped between the core and the coil, which, when moving the speaker cone, causes an unpleasant sound in the form of a speaker wheezing.Speaker repair consists in disassembling the speaker and removing the source of the unpleasant sound.

A wheezing four-way coaxial speaker from Pioneer was repaired. The main tool for disassembling the speaker, a regular, flat screwdriver and a soldering iron.

First of all, I removed the buzzer module. In this model, the buzzer module was fastened with a long bolt, which was hidden under the magnet sticker. On other models, the tweeters can be simply glued, in which case they need to be ripped off, but before that, if possible, unsolder the wires going to the tweeters.

In the lower photo, if you look closely, you can see debris between the metal core and the sound winding.

After the tweeter module was unscrewed and the wires were soldered from it, armed with a screwdriver, he forged the plastic cover that presses the rubber suspension of the diffuser and carefully, slowly, was peeled off.

With the same tool, I peeled off the diffuser suspension. With a screwdriver, it is enough to pry it off a little, then you can peel it off with your hands.

I unsoldered the wiring to start peeling off the centering washer.

Peeling off the centering washer is a little more difficult than previously peeled off parts, you can't rush here, it is easy to damage the washer.

There was a lot of debris inside the speaker, no wonder it was constantly wheezing.

On the voice coil of the speaker, scratches are visible, proving the presence of foreign objects, the insulation of the winding is damaged. The protective layer of the winding, it is desirable to restore, for this you can open it with varnish or epoxy resin over the scratches, with a small layer.

We clean, wash, vacuum all parts of the speaker.

Well, now the most difficult thing that had to be faced with the repair of speakers is the removal of metal particles magnetized to the core. A vacuum cleaner cannot cope with them. Scotch came to the rescue, with the help of just such not cunning actions, everything that was superfluous in the dynamics was removed.

Then it was necessary to glue everything into place. I glued the speaker with ordinary, universal glue. Moment.

I did not remove the old traces of glue, since it is easy to navigate along them when gluing the speaker, which allows you to glue it correctly and without distortions. But all the same, you need to check if the winding clings to the core when the diffuser moves.

If everything went well, there is no extraneous noise when the diffuser moves, we add it, solder it, assemble the speaker.

Refurbished speaker, pictured on the right. The speaker repair was successful, everything works and does not wheeze.

There is absolutely nothing in disassembling the speaker, there is nothing complicated, everything is simple and easy, the main thing is not to rush. It took me about an hour to repair one speaker.

Has the speaker wheezed or stopped sounding and want to bring it back to life? First, diagnostics. We remove the speaker, disconnect the wires from the terminals, having previously marked the polarity. In the future, we adhere to this rule: everything that we disassemble, draw or photograph will help a lot.

We check the winding resistance with the device. There are three options here.
1) Break.
2) Nominal resistance.
3) Reduced resistance.

Now the second check. We put the speaker on the magnet and gently move the diffuser up and down. If you hear a rustle or creak, or there is no movement, the speaker will have to be disassembled.

If there is no grinding, and the winding is open - you need to check the conductivity of the flexible wires from the terminals to the soldering of the winding. They are made of threads intertwined with copper veins that break over time. They can be replaced without disassembling the speaker with M.G. T.F. a suitable cross-section or a braid tape to remove excess solder.
We solder the wires so that they do not stretch when the diffuser moves and do not touch it. We glue the place of soldering with Moment glue.

If the speaker needs to be disassembled, disconnect the wires from the terminals, put the speaker on the magnet and with a swab dipped in acetone, soften the glue around the protective cap and remove it, prying it off with a non-sharp scalpel.In the same way, peel off the outer edge of the diffuser and the outer edge of the centering washer. Carefully pull the diffuser straight up without skewing.

I do not recommend unsticking the coil frame from the diffuser and centering washer, so as not to disturb the centering of the speaker.

To rewind, you need to assemble a simple device, the device of which is clear from the figure. The hardest part is the spool holder. To make it, you need to contact a turner. Mandrel length 100-150 mm, material - any metal.

We measure the inner diameter of the coil (x). The mandrel for the spool should have a diameter of x + 0.5 mm at one end and x-0.5 mm at the other end.
On the large end, we drill a 3.2 mm hole and cut an M4 thread for attaching the handle.
We drill a 6.5 mm through hole for the stud. The surface of the mandrel must be sanded.

Now you can start winding. We need alcohol-based glue, for example, BF-2 or BF-6, paper from the MBM capacitor, wire and a lot of patience.

We dilute the glue with alcohol. We pierce the centering washer with a needle, thread the winding wire and solder it to the flexible wire. We fix the wire at the soldering point and at the beginning of the winding by gluing pieces of paper.
If the coil frame is made of metal, we glue it with a layer of paper from the capacitor without overlapping layers. We wind the wire coil to coil, gluing it before winding and over it. Remove excess glue with your finger. We try to wind not tightly, but tightly.

On the first layer we glue the paper from the capacitor without overlapping layers and perform the same actions in reverse order. When the winding is ready and soldered to the terminals, you need to connect them to a 4-5 Volt power source with a current of 1-2 Amperes to dry. The winding will heat up to 50-60 degrees, while the glue will dry and harden, the coil will expand slightly. This will help to easily remove it from the mandrel.

We check the free play of the coil in the speaker gap and start assembling.
We need to align the coil exactly to the center. There are 2 ways to do this.
1) Place a film or X-ray film gasket in the gap.
2) Apply a small constant voltage of 2-3 Volts to the coil so that it is slightly pulled inward.

Apply a layer of Moment glue to the outer edge of the diffuser and the outer edge of the centering washer and lower the diffuser vertically downward without skewing and without radial displacement, press. You can turn the speaker over onto a flat table and while the glue dries, solder the wires to the terminals.

After the glue dries, remove the gasket and check the free play of the coil in the speaker gap.
If everything is in order, we glue the protective cap in place and enjoy the result!

Today, the number of good sound lovers who just throw out a wheezing speaker is not decreasing! At the same time, the cost of an analogue can be a tangible amount. I think the following will help anyone who has hands that grow out of the right place to fix the speaker.

Available - a miracle of design thought, once the former column S-30 (10AC-222), now serving as one of the autosubs. A week later, after the mutation, the patient began to show signs of the disease - he emitted extraneous overtones when working out the bass parts, wheezed a little. It was decided to conduct an autopsy.

After autopsy, a diseased organ was removed from the patient's body - woofer 25GDN-1-4, 86 of release. The organ clearly needed operation - when gently pressing the diffuser, an extraneous sound was heard (very similar to a quiet click), and when ringing in various tones (generated by the nchtoner program), a clearly audible rattling-crackling sound was heard with a large diffuser stroke and when ultra-low (5-15Hz) ) frequencies. It was decided to trepan this organ

First, the patient's flexible lead wires were sealed off (from the side of the contact pads)

Then a solvent (646 or any other capable of dissolving glue, such as "Moment") was moistened with a syringe with a needle, the place where the dust cap and the diffuser were glued (along the perimeter).

... the place where the centering washer is glued to the diffuser (around the perimeter).

... and the place where the diffuser itself is glued to the basket of the diffuser holder (again around the perimeter)

In this state, the speaker was left for 15 minutes with periodic repetition of the previous three points (as the solvent was absorbed / evaporated)

Attention! When working with a solvent, safety measures should be observed - avoid contact with skin (use rubber gloves!) And mucous membranes! Do not eat or smoke! Work in a well ventilated area!

When wetting - use a small amount of solvent, avoiding getting it on the gluing area of ​​the coil and centering washer!

Depending on the type of solvent and air temperature, after 10-15 minutes of the above operations, using a sharp object, you can gently pry off the dust cap and remove it. The cap should either come off very easily or offer very little resistance. If you need to apply significant force, repeat the operations with wetting its edges with a solvent and waiting!

After peeling off the cap, carefully pour out the remaining solvent from the recess near the coil mandrel (by turning the patient over).

By this time, the centering washer has time to peel off. Carefully, without using any efforts, we separate it from the basket of the diffuser holder. if necessary, re-wet the gluing site with a solvent.

Wet the place where the diffuser is glued to the diffuser holder. We wait. We wet again and wait again. After about 10 minutes, you can try to peel off the diffuser. Ideally, it should detach from the diffuser holder (together with the coil and centering washer) without effort. But sometimes he needs a little help (the main thing is accuracy! Do not damage the rubber suspension.)

We clean the gluing points from the old glue and dry the disassembled speaker. We examine the disassembled patient for a malfunction. We look at the coil. If there are no scuffs and loose turns on it, we leave it alone. When peeling off the coil, glue it back with a thin layer of BF-2 glue.

We carefully inspect the place where the lead wires are attached to the diffuser. So it is - the patient has the most common malfunction in old speakers with a large diffuser travel. The lead wire at the attachment point is frayed / broken. What kind of contact can we talk about when everything hangs on a thread passed into the center of the wiring!

Gently bend back the copper antennae.

... and unsolder the lead wires.

We repeat the operation for the second wiring (even if he is still alive - the disease is easier to prevent!)

We cut the supply wiring at the break point.

... and we serve the resulting ends (of course - first we use rosin). Here you need to be careful! Use a small amount of low-melting solder - the solder is absorbed into the wire like a sponge!

Gently solder the wiring into place, bend the copper "antennae" and glue (Moment, BF-2) the place where the wiring adheres to the diffuser. Remember - you cannot solder the wires to the fastening "antennae"! Otherwise, how can the wiring be changed again in ten years?

We collect the speaker. We put the diffuser with the entire “household” into the diffuser holder, orienting the wiring to the places of their attachment. Then we check the correctness of the polarity - when connecting a 1.5V AA battery to the terminals, when connecting the “+” battery to the “+” of the speaker, the diffuser will “jump out” of the basket. We put the diffuser so that its “+” lead wiring is at the “+” mark on the speaker basket.

We solder the lead wires to the contact pads. Please note that the length of the wires has decreased by almost half a centimeter. Therefore, we solder them not as it was at the factory - to the hole in the plate, but with a minimum margin to maintain the length.

We center the diffuser in its basket using photographic film (or thick paper), which we place in the gap between the core and the coil. The main rule is to place the centering evenly around the perimeter, to maintain the same gap. The amount (or thickness) of the centering should be such that when the diffuser is slightly protruding outward, it freely rests on it and does not fall inward.For the 25GDN-1-4 speaker, 4 pieces of film are enough for this, placed in pairs in front of each other. The length of the film should be such that it would not interfere if you put the speaker on the diffuser. For what - read below. We glue the diffuser. We use the indication for the glue used (I recommend "Moment", the main selection criterion, so that the glue can be subsequently dissolved with a solvent). I usually stick out the diffuser 1-1.5 cm up so that the centering washer does not touch the basket of the diffuser holder, then I apply a thin layer of glue on it and the basket with a brush, wait and firmly push the diffuser inside, additionally press the washer against the basket around the perimeter with my fingers ... Then I glue the diffuser (in the retracted state, avoiding distortion).

We leave the speaker upside down for several hours under load (this is why our film should not protrude beyond the plane of the diffuser!).

Then we check the speaker for correct assembly. We take out the centering and carefully check the diffuser travel with our fingers. It should walk easily, without emitting overtones (there should be no touching of the coil and core!). We connect the speaker to the amplifier and send low-frequency tones of low volume to it. Extraneous sounds should be absent. In case of improper gluing (misalignment, etc.), the speaker must be glued (see above) and reassembled, being careful! With a high-quality assembly, we get 99% of a fully working speaker.

We glue the edge of the dust cap with glue, wait and carefully glue it to the diffuser. Here you need accuracy and precision - a crookedly glued cap does not affect the sound quality, but it spoils the speaker's appearance very much. when gluing, do not press on the center of the cap. It can bend from this and you will have to peel it off, straighten it, coat it from the inside with a thin layer of epoxy for strength and stick it back.

We wait until all parts are completely glued together (about a day) and put the finished speaker in its place. We enjoy sound that is no worse than that of a new factory analogue speaker.

That's it, now you can see that fixing a speaker is an easy task. The main thing is slowness and accuracy! So in an hour, you can slowly repair almost any woofer or midrange speaker of domestic or foreign production (for gluing imported speakers, a more powerful solvent is often required, such as acetone or toluene, carefully - they are poisonous.) Having a similar defect.

Yes, after the operation, the former patient got a second wind and the cheerful yellow subs continue to do their hard bass work:

Save and read later -

To do this, you will need the following basic materials:

1. Suspension matching the dynamics

2. Any contact adhesive (Moment-1, 88)

3. Latex or diluted PVA

The hangers are supplied uncut both in terms of inner and outer dimensions. are used not only for the repair of 75 GDN. It must be cut to the desired diameter.

The cap is peeled off by soaking the glue with acetone. The place for the suspension glue is cleaned (on the diffuser and the holder). The diffuser is cut around the perimeter by 2 mm. Using strips of paper (plastic, etc.), the movable system is centered (the strips are placed in the gap between the coil and the core of the magnetic system). Contact glue is applied to the suspension, diffuser and holder (the suspension will first lose its shape, then return to its original position). And, armed with dexterous hands, we evenly lower the suspension onto the diffuser and holder. It is better to slightly pull the diffuser out of the holder so that it first rests on the diffuser, and then together with it glue it to the holder. We take out the strips, control the build quality and glue the cap. To do this, you can use PVA or 88 glue.

To facilitate the process, you can peel off the washer from the diffuser by soaking it with acetone (since the quality of the adhesives of our speakers leaves much to be desired), and unsolder the leads (or it is better to replace them altogether).

You can, of course, peel off the washer from the holder, using the solvent 88 of the glue - ethyl acetate.

Then, you need to put the suspension on a flat surface, spread the diffuser and suspension with glue, and then lower the diffuser with the coil onto it. Then we put 88 glue on the suspension, the holder, and the BF on the diffuser and the washer, center the movable system using the above method and glue it in.

It is considered good practice to pour latex (or diluted PVA) onto the place indicated in the figure.

It is also good to make holes under the hood for better ventilation.

Recently, a dynamic head was brought in for repair, its suspension was worn out. I decided to share a simple speaker repair technology with you, dear radio amateurs. So, everything is very simple, and for repairs we need to have a transparent adhesive tape and glue at hand (rubber, waterproof), if such glue is not available, we can do with universal waterproof. We take scotch tape and glue the holes and torn points of suspension with it.

After everything is already pasted over, make sure that there are no small holes left (so that there is no leakage of the poured glue). To give it a round shape, the tape should be slightly warmed up (you can use a lighter).

Next, we begin the restoration of the speaker suspension. We take the glue a moment and spread it on tape, try to do it as neatly and smoothly as possible. Make sure the glue has settled evenly. Then you need to leave the head to dry.

The glue dries out within 5-7 hours, and then turns into rubber. During the drying of the glue, the head must be placed on a flat surface so that the glue is evenly high throughout the suspension.

After a few hours, the dynamic head is ready for use. There is almost no difference between factory and home-made gimbals, the sound is clear and of high quality, by the way, the client really liked it, I hope you will like it too.

In general, for many years, I used almost this technology to replace the suspension of the dynamic heads of the C-30 radio technician. These heads have a fairly high-quality sound, feel great at low frequencies (though the midrange is lame), in a word, a good head for a powerful subwoofer, but there is one drawback - the foam suspension. At deep bass at full volume, it will last no more than 20 minutes. I used dozens of ways to replace the suspension of such a head, but none of them satisfied - either the wheezing, then the speaker becomes very hard, then the centering is disturbed and the varnish is peeled off the coil, but then I just decided to make a homemade suspension for such a head using the tape and glue method for a moment. The result was amazing! The head became the basis for a powerful car subwoofer and has been used in a friend's car for 3 years. The amplifier is powerful, assembled on the basis of the famous TDA7294, whose peak power can reach up to 110 watts! And imagine - the head can easily withstand this power, and the suspension does not break.

And here's another secret of homemade gimbal - don't spare the glue! The more it needs to be filled, the better, and if at home there are dynamic heads with a worn out suspension (such a defect occurs very often) then do not rush to throw them out, they will serve you faithfully for several years! For pre-fixing the tape, it is advisable to use super glue. This alteration will not affect the dynamics parameters, and the response to low frequencies will even be better than at the time when the speaker was released from the factory - AKA.

Acoustic systems are divided into active, passive, the difference is limited by the presence of sound processing chips inside, powered by electric current. Amplifiers, filters, interfaces for reading flash media, decoding compressed audio formats. In the latter case, the speaker system approximates the functionality of the player.Consider what to do when the speakers are not working. The speakers include a myriad of sound reproducing devices, readers are interested in how they repair speakers with their own hands. You will need special glue. In the days of the USSR, BF 4, AK 20. Accordingly (based on glue), solvents are selected. It will be necessary, disassembling, dismantling the connection, and repairing the speaker system yourself.

A movable part with a rigid plate creates air vibrations that are perceived by the human ear.

Do-it-yourself repair of acoustic systems, doubting how the device works, is supposed to use the principle - do not harm. Regardless of the size, the speaker of the speaker system is formed by electrical, mechanical parts. The first is formed mainly by inductors. The second includes a permanent magnet, a membrane. Here is an incomplete classification of speakers of acoustic systems.

Readers are familiar with naturally occurring audio reproducing devices. It is not always possible to find an inductor in the speaker system. Therefore, before the repair, in the process, the master performs the correct classification of the devices, properly carrying out the necessary operations.

Partially touched the device. Let's consider in more detail the electrodynamic models. The diffuser forms the support for the cap. It is represented by the semblance of a wide horn on which the coil is glued from the back side. Flexible copper conductors, carrying an electric current, fit directly to the membrane cap, punching the diffuser from the inside. The soldering points are visible from the front of the speaker. The coil is light; it is required to provide a relatively low inertia of the system. Even the tuning fork A of the first octave lies at 440 Hz. It is clear that for fluctuations of the indicated speed, the moving part of the speaker of the acoustics must be light.

The magnet is fixed on the bed. Usually circular. An inductor runs in both directions in the hole, moving the cap-membrane assembly. The connecting wires make constant vibrations. A centering washer is used to position the movable part along the vertical, horizontal axis. Perforated piece of elastic material, centering the location of the cap, diffuser. The centering washer does not interfere with the displacement of the moving part along the axis of symmetry. The repair is ridiculously simple:

Since the membrane and cap do not break, it is a matter of checking the electrical installation, the soldering points of the wires, the integrity of the coil.

Inductance is wound in the image and likeness of the old one. Each layer of turns is coated with BF 4 glue. Poor soldering is performed anew. Select the appropriate inductance winding technique. Usually a special device is made, formed by two pairs of racks, standing opposite each other on a long board. Both are connected by axles. One contains the core of the new coil, the other contains the purchased wire. It is recommended to buy the wire with varnish insulation. It is necessary to maintain the correct thickness. You can measure using a vernier caliper.

Winding is relatively fast while the glue dries. The coils fit tightly to one another, adhering to the shuttle principle. It is important to maintain the correct number of turns, properly position the terminals.

It is often necessary to disassemble a speaker of a speaker system for repair. Stock up on solvent. The glued joints are wetted, waiting for a fixed time. Please note: the joints are carefully cleaned. It is made regardless of the glue used to assemble the speaker of the speaker system.

Speakers are different types of speaker systems, each with a limited frequency response. Everyone works as a kind of mechanical filter. However, it happens that you need to shift the range ... You can raise the resonance frequencies of the electrodynamic system by varnishing the centering washer. Used 5-10% solution of ZAPON, cellulose in acetone. The varnish is applied with a soft brush in a circle.Avoid misaligning the moving part of the loudspeaker. Consecutively performing the operations, we will increase the resonance frequency by 1.5–2 times, approximately one octave.

To lower the range, weights should be glued to the moving part. The correct ring of cardboard is attached to the back of the diffuser. It is necessary to more precisely maintain the symmetry of the arrangement of parts. The sound pressure drops rapidly. The volume decreases, the range is narrowed from the high frequency side. However, in the area of ​​resonance, the loudspeaker will perform well.

You can expand the range in both directions (if there is no cap). In the center, from the front, a truncated cone is glued above the inductance coil of the speaker of the speaker system. The mass is made as small as possible. Thin, thick paper impregnated with ZAPON varnish will do. The top plate is equal to the coil, the height is half the cone, the taper is 70 degrees. Due to the increase in the mass of the moving part, the resonant frequency decreases, but the upper edge of the range rises, thanks to the rigid core, which is harder than the diffuser. As a result, the spectrum of the reproduced sounds expands in both directions. The total increase will be one and a half or two octaves, the game is worth the candle. Take care to correctly configure the electronic part: if there are passive filters on capacitors and resistors, they will limit (cut off) the capabilities of the mechanics.

Craftsmen increase the sound pressure at the resonant frequency for an unshielded magnetic system. Try to find one or a similar set ring. Then glue the second magnet on the reverse side of the one standing, the interaction of the fields will increase, therefore, the strength of the sound will increase.

The speaker system is simple and can break, they said. We hope the renovation goes off without a hitch.

How good it is sometimes in the summer on the street in a cool gazebo to listen to your favorite tracks ... We got together like that in the summer with a friend sat listening to some drummer on his old S30 Radiotehnika. Surprisingly, the columns, in spite of their already advanced age, were always hollowed out very well. But after a couple of tracks at full power of this ULF, one of the speakers began to wheeze strangely ...

Thinking about what happened, I started looking for the reason in the ULF, disassembled the amplifier and measured all the voltages. Everything turned out to be normal. After that I decided to swap the channels and turned on the sound for the whole ... All the same column with the same effect. I had to repair, by the way, this is not the first speaker repair, I already had experience in repairing the Chinese speaker of the Sven speaker

After the autopsy, it turned out that the inside was GDN 25, which I had previously seen only in pictures on the Internet.

Here is a photo of the speaker of the GDN 25

Having twisted the speaker and examined it from all sides, no defects were found. But then I slightly pressed down the diffuser, I found that the diffuser was torn off from the centering washer, which can be clearly seen in the photo

Rub the diffuser against the core of the magnet and if this nuisance is not eliminated, then in addition to the grinding, which presses on the ear, the sleeve will fray and close the coil, which can lead to the destruction of the ULF. Fortunately, such repairs are carried out very quickly and will not take much effort.

To repair the speaker, we need:

Glue. I used regular rubber, liquid 88 glue

Acetone. I used regular nail polish thinner.

Syringe. For easy bonding of the diffuser

When everything is ready, you can start repairing

You need to remove the dust cap to get to the speaker coil. To do this, you need to slowly soak the edges of the cap with acetone to soak the glue. It is convenient to do this using the same syringe. The photo clearly shows what needs to be done! The photo shows how the solvent has not yet been absorbed.

After the cap is soaked, it literally takes about 5 minutes, we carefully try to pry it by the edges, only very carefully because the diffuser can be damaged.If the cap does not slip, add more acetone. It should slide easily.

Here is the cap removed

As you can see, the speaker is still damp. He needs to be allowed to dry, literally half an hour is enough for this, this is in the summer and just not in the sun. Drying should be done in the shade and in a well-ventilated place ..

When the speaker is dry, we need to center the speaker. To put it simply, it is necessary to align the sleeve so that it does not touch the core at full speed. This is done using regular film from a camera. If it is not there, you can use an old X-ray photograph, or at worst, as I did, take an ordinary thick thin notebook cover.

So you need to twist the film into a tube and insert it between the core and the sleeve

And press down tightly so that the diffuser is well pressed against the washer. Then we collect the syringe with glue, so the thinner the glue, the better

And now we carefully glue the washer with a good layer of glue. Be careful. Hold the needle, because under the pressure of the piston, it sometimes flies out and can get injured.

Stretch out with glue as seen in the photo

After you have stretched it once, look carefully, perhaps there is not enough glue and you need to walk again .. Remember that the quality of your work depends on the quality of the sound and the absence of alterations.
This completes the repair. Once again, check if the washer is pressed tightly and leave the speaker to dry for a day until the glue completely solidifies.

After a day, we carefully take out the centering film and try to connect the speaker for testing. Drive it well and check its strength. If everything is normal, glue the cap back in place and put the speaker in the speaker. This completes the repair

Here are a couple more photos of the speakers Radiotehnika S-30

The repair is over. A year has already passed since this speaker works and it still pleases with its sound. Therefore, do not be afraid to repair the speakers and do it with high quality so that you do not have to repeat the repair. And just good luck to you
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