Today, the number of lovers of good sound who simply throw away a wheezing speaker is not decreasing! At the same time, the cost of an analogue can amount to a significant amount. I think that the following will help anyone who has hands that grow from the right place to fix the speaker.
Available - a miracle of design thought, which was once a column S-30 (10AC-222), now performing the functions of one of the autosubs. A week after the mutation, the patient began to show signs of the disease - he made extraneous sounds when practicing bass lines, and wheezed slightly. A decision was made to perform an autopsy.
After the autopsy, the diseased organ was removed from the patient’s body - a woofer 25GDN-1-4 manufactured in 1986. The organ clearly needed surgery - when you gently pressed the diffuser, an extraneous sound was heard (very similar to a quiet click), and when ringing with different tones (produced by the nchtoner program), a clearly audible scratching-crackling sound was heard with a large stroke of the diffuser and when applying ultra-low (5-15 Hz) ) frequencies. It was decided to trepanate this organ
First, the patient's flexible lead wires were unsoldered (from the side of the contact pads)
Then, with a solvent (646 or any other capable of dissolving glue, such as “Moment”), using a syringe with a needle, the place where the dust cap and diffuser were glued together (around the perimeter) was moistened...
Place where the centering washer is glued to the diffuser (along the perimeter)...
And the place where the diffuser itself is glued to the diffuser holder basket (again around the perimeter)
The speaker was left in this state for about 15 minutes with periodic repetition of the previous three steps (as the solvent was absorbed/evaporated)
Attention! When working with solvent, you should observe safety precautions - avoid contact with skin (work with rubber gloves!) and mucous membranes! Don't eat or smoke! Work in a well-ventilated area!
When wetting, use a small amount of solvent, avoiding getting it on the place where the coil and centering washer are glued!
Depending on the type of solvent and air temperature, after 10-15 minutes of the above operations, using a sharp object, you can carefully pry up 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 operation by wetting its edges with 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 come off. Carefully, without any effort, separate it from the diffuser holder basket. if necessary, re-wet the gluing area with solvent.
We wet the place where the diffuser is glued to the diffuser holder. We wait... We wet it again and wait again... After 10 minutes you can try to peel off the diffuser. Ideally, it should effortlessly separate from the diffuser holder (along with the coil and centering washer). But sometimes he needs a little help (the main thing is to be careful! Do not damage the rubber suspension!!!) 
We clean the gluing areas from old glue and dry the disassembled speaker. We examine the disassembled patient to determine if there is a malfunction. Let's look at the reel. If there are no abrasions or loose threads on it, we leave it alone. When a thread comes off, glue it back with a thin layer of BF-2 glue.
We carefully inspect the place where the supply wires are attached to the diffuser. So it is - the patient has the most common malfunction found in old speakers with a large diffuser stroke. The supply wire at the attachment point is frayed/broken. What kind of contact can we talk about when everything hangs on a thread running through the center!
Carefully bend the copper “tendrils”...
And unsolder the supply wire.
We repeat the operation for the second transaction (even if he is still alive - the disease is easier to prevent!)
We cut off the supply wires at the break point...
And we tin the resulting ends (of course, we first use rosin). Care is required here! Use a small amount of low-melting solder - the solder is absorbed into the wiring like a sponge!
Carefully solder the wiring into place, bend the copper “tendrils” and glue it with glue (Moment, BF-2) where the wiring connects to the diffuser. Let us remember - you cannot solder wires to the fastening “antennae”! Otherwise, how can the wiring be changed again in ten years?
Assembling the speaker. We place the diffuser with all the “equipment” in the diffuser holder, orienting the wiring to the places where they are attached. Then we check the correct polarity - when connecting a 1.5V AA battery to the terminals, when connecting the “+” battery to the “+” speaker, the diffuser will “jump” out of the basket. We place the diffuser so that its “+” supply wire 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 centering should be such that when the diffuser is slightly protruded outward, it will freely rest on it and not fall inward. For the 25GDN-1-4 speaker, 4 pieces of photographic film, placed in pairs in front of each other, are enough for this. The length of the photographic film should be such that it does not interfere if you place the speaker on the diffuser. For what - read below. Glue the diffuser. We use the indication for the glue used (I recommend “Moment”, the main selection criterion, so that the glue can later be dissolved with a solvent). I usually stick the diffuser 1-1.5 cm up so that the centering washer does not touch the diffuser holder basket, then I apply a thin layer of glue to it and the basket with a brush, wait and firmly push the diffuser inside, additionally pressing the washer to the basket around the perimeter using my fingers . Then I glue the diffuser (in the retracted state, avoiding distortion).
We leave the speaker upside down for several hours under a load (this is why our photographic 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 movement of the diffuser with our fingers. It should walk easily, without making overtones (there should be no touching of the coil and the core!). We connect the speaker to the amplifier and feed it low-frequency tones at a low volume. There should be no extraneous sounds. If the gluing is incorrect (misalignment, etc.), the speaker must be unstuck (see above) and reassembled, being careful! With high-quality assembly, 99% of the time we will get a fully working speaker.
We coat the edge of the dust cap with glue, wait and carefully glue it to the diffuser. Care and precision are required here - a crookedly glued cap does not affect the sound quality, but it greatly spoils the appearance of the speaker. When gluing, do not press on the center of the cap!!! This may cause it to bend and you will have to peel it off, straighten it, coat the inside with a thin layer of epoxy for strength and glue it back.
We wait until all the parts are completely glued together (about a day) and put the finished speaker in its place. We enjoy the sound, which is no worse than that of a new factory similar speaker.
That's it, now you see that fixing a speaker is an easy task. The main thing is slowness and accuracy! So, in an hour, you can leisurely repair almost any woofer or midrange speaker, domestic or imported (for gluing up imported speakers, a more powerful solvent is often required, such as acetone or toluene, be careful - they are poisonous!!!) that has a similar defect.
Yes, after the operation, the former patient got his second wind and the cheerful yellow subs continue to do their hard bass work.
Have the speakers of your favorite acoustics begun to wheeze? Do not rush to write them off; with such symptoms it is very easy to repair the speakers yourself. Usually the speaker begins to wheeze due to the numerous dust that has accumulated over the years of trouble-free operation between the core and the coil, which, when the speaker cone vibrates, generates an unpleasant sound in the form of speaker snoring. In this case, speaker repair must begin with disassembling and removing dust or small debris that causes a wheezing sound.
Structure and design of speakers |
To repair speakers, it is important to understand how a typical representative from the world of audio technology works; let’s analyze its structure and design, for this we turn to the figure below.
The speaker consists of a magnetic system located on the rear side. It consists of a ring magnet made of special ferromagnetic alloys or magnetic ceramics, steel flanges and a cylinder (Kern). There is a gap between the core and the flange in which a magnetic field is generated. In the gap, there is an inductor coil wound with a thin copper wire on a rigid cylindrical frame. It is also sometimes called a voice coil. The coil frame is attached to a diffuser - it is this that “moves” the air, creating compression and discharge - acoustic waves.
The diffuser can be made from a variety of materials, but is usually made from compressed paper pulp. To prevent the coil from touching the core walls, it must be placed in the middle of the magnetic gap using a centering washer. The diffuser is mounted on a metal frame. Its edges are corrugated to allow free vibrations.
Thin wires from the coil go to the outside of the diffuser and are fastened with special rivets, and a stranded copper wire is attached to them on the other side. These stranded conductors then go to the petals, which is how the speaker is connected to the circuit.
Now you can start repairing the speakers yourself.
Speaker designation on the diagram |
If an alternating electric current is passed through the voice coil, it will appear, which will interact with the constant magnetic field of the speaker system. This causes the coil to either be pulled into the gap or pushed out of it the other way, depending on the direction of the currents. The mechanical vibrations of the coil are transmitted to the diffuser, which oscillates in time depending on the frequency of the alternating current, generating acoustic vibrations.
The speaker in the diagrams is designated as follows. Next to the designation there are the letters B or BA and the serial number of the speaker in the circuit.
Using the Focal Polyglass 165 VRS model as an example, since these speakers have high sound quality and, accordingly, are very expensive, I decided to try to repair them. On both speakers, upon visual inspection, I noticed a break in the wiring, and it was impossible to solder without disassembling.
The diffuser in this speaker was woven from fabric. Rubber suspension. It took about an hour to disassemble the head. To separate the suspension I used a solvent. The main problem was that the main frame of the head was made of plastic, which was “dissolved” by a solvent.
The centering washer was separated with a mounting knife, and access to the coil appeared. It is usually screwed onto a metal sleeve to a very high precision tolerance. The sleeve itself is interesting with holes for cooling. The cap is made of plastic. All that remains is to solder the new flexible wires to the coil.
The assembly process must be carried out in reverse order, what was peeled off with such difficulty must be glued back, I used super glue for this, as it dries quickly. If you use long-drying glue, you will have to press it under a press and make special templates. An hour later I turned on the speakers, the sound was simply magical.
Speaker repair completed successfully
I doubt that this miracle device has much practical value, but anyone can assemble it just for fun in about thirty minutes. Although you may have had an unsuccessful repair and something is better than nothing.
The simplest electrostatic speaker is designed like this: the film is located parallel to a flat metal plate with holes for the free passage of air. Gap ( d) between the surface and the film, they try to make as little as possible, but nothing should interfere with the vibrations of the film.
If some voltage U n with a nominal value of about hundreds of volts (polarizing) is applied between the plate and the film with oscillations of the sound frequency U superimposed on it, then an electric field is formed in the air gap, causing some attraction between the plate and the film, thereby creating sound.
DIY electrostatic speaker design. The dimensions of the plates are 160 by 180 mm, each has many holes with a diameter of 2 mm. The plates must be slightly concave on the foil side, otherwise spacers will be required.
The design of a loudspeaker driver is shown in the figure above. The plates 1 are arranged foil to each other, between them there is a sheet of plastic film 2 (with metallization on the right), and the entire system is connected by screws 3 at the corners with a thickness of about 35 microns. You need to find insulating washers under the screws, and you need to make 4 conclusions from the foil of the plates, for the speaker terminals, or you will need to make protrusions on the plates and solder the wires directly to the foil on the protrusions.
If the plates used do not have a natural concavity, a thin cardboard spacer 5 should be installed around the perimeter on the side of the film where there is no metallization.
To reduce the effect of “acoustic short circuit”, it is advisable to install the loudspeaker in some kind of housing; the polished side wall of the housing of a very old CRT TV is perfect for this.
To test the homemade product, I used a self-assembled
Better acoustic results can be obtained with a differential design of electrostatic loudspeakers, in which the film does not experience a constant force of attraction due to the polarizing voltage, and oscillates much more easily, encountering only some air resistance. However, here you will need two antiphase sound voltages of the same amplitude, obtained from a transformer with a symmetrical secondary winding. You will also need a two-layer film with metallization in the middle.
A little theory for speaker repairThe theory behind our simplest speaker, the loudspeaker, is extremely simple: applied voltage U generates a field strength E = U/d. Per charge q there is a force in this field F = qE. And the sound pressure created by the loudspeaker at the membrane itself: p = F/S, Where S- membrane area. Divide by area and get р = qE/S. Magnitude o = q/S is called the surface charge density (we assume that the charge is distributed uniformly over the surface of the membrane film). Then p = aE. Surface charge density is directly related to field strength: e0E = a, where e0 = 8.85*10-12 F/m- electrical constant. Finally we have: p = e0E2. The expression on the right corresponds to twice the volumetric energy density of the electric field, which is what the sound pressure is proportional to!
That is why we must try to increase the field strength (the voltage between the film and the plate) and reduce the gap d between them. The limit is imposed by the electrical strength of the air - too high a field strength causes a quiet or even corona discharge.
Sound pressure is proportional to the square of the field strength, and therefore the applied voltage U. It does not depend on the polarity of U, which forces us to use, in addition to sound, a constant polarizing voltage. To reduce “square” distortion, U is chosen much larger than U.
As a consequence of the speaker design, it is, in its direct essence, a typical transducer that converts an electrical signal into sound waves. But in accordance with Faraday’s law, when we tap the cone lightly, a sinusoidal signal is formed at its contact. The position of the first half-cycle of the generated signal determines the polarity of the device. Thus, in accordance with the diagram below, the position (positive and negative) of the half-cycle of the signal from the speaker is recognized.
The polarity of the device is determined as follows:
If the first half of the sine wave cycle is positive: it is amplified by the op amp (IC1:C) from the loudspeaker. This amplified signal is then fed to the input of the gate (IC2:C), and its second input is connected to output 2 of flip-flop IC3:A. When the amplified signal is in the logic one state, the output of the logic gate is also one, which switches flip-flop IC3:B, and LED1 will blink once.
When the first half of the sine wave is negative, LED2 will blink once.
It’s so good sometimes in the summer on the street in a cool gazebo to listen to your favorite tracks... One summer we gathered at a friend’s house, sat and listened to some kind of drama on his old S30 Radiotehnika. Surprisingly, the speakers, despite their advanced age, always played very well. But after a couple of tracks at full power, 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 up the volume all the way... Still the same speaker with the same effect. I had to repair it, by the way, this is not the first repair of the speaker, I already had experience repairing the Chinese speaker of the Sven speaker
After opening it, it was discovered that inside there was a GDN 25, which I had previously only seen in pictures on the Internet.
Here is a photo of the GDN 25 speaker
Having twisted the speaker and examined it from all sides, no defects were found. But then, pressing the diffuser a little, I discovered that the diffuser was torn off from the centering washer, which is clearly visible in the photo
The diffuser rubbed against the core of the magnet and if this problem is not eliminated, then in addition to the grinding noise that puts pressure on the ear, the sleeve will rub and short-circuit the coil, which can lead to the failure of the ULF. Fortunately, such repairs are carried out very quickly and do not require much effort.
To repair the speaker we will need:
Glue. I used regular rubber, liquid 88 glue
Acetone. I used regular nail polish remover.
Syringe. For ease of diffuser gluing
When everything is prepared, you can start repairing
You need to remove the dust cap to get to the speaker coil. To do this, you need to slowly wet the edges of the cap with acetone to loosen 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 off by the edges, just be very careful because you can damage the diffuser. If the cap does not slide off, add more acetone!!! It should slide off easily.
Here is the cap removed
As you can see, the speaker is still raw. It 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.
Once the speaker is dry, we need to center the speaker. To put it simply, you need 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 you don’t have it, you can use an old X-ray image, or at worst, as I did, take an ordinary thick, thin notebook cover.
But 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 pressed well against the washer. Then we fill the syringe with glue, so the thinner the glue, the better
And now 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 you can get hurt.
We stretch it with glue as seen in the photo
After you have stretched it once, look carefully, maybe there is not enough glue and you need to go through it again.. Remember that the quality of your work depends on the quality of the sound and the absence of rework.
This completes the repair. Once again, check whether the washer is pressed tightly and leave the speaker to dry for a day until the glue completely hardens.
After a day, we carefully take out the centering film and try to connect the speaker for testing. Drive it well and test its strength. If everything is normal, glue the cap back in place and put the speaker in the column. The repair is complete
Here are a couple more photos of Radiotehnika S-30 speakers
The renovation is complete. A year has already passed since this speaker works and still pleases with its sound. Therefore, do not be afraid to repair speakers and do it efficiently so that you do not have to repeat the repair. And just good luck to you
With uv. Admin check
Recently they brought in a dynamic head for repairs whose suspension was worn out. I decided to share a simple technology for repairing speakers with you, dear radio amateurs. So, everything is very simple, but for repairs we need to have on hand transparent tape and instant glue (rubber, waterproof), if such glue is not available, we can get by with a universal waterproof one. We take tape and cover the holes and torn areas of the suspension with it.
After everything is pasted over, make sure that there are no small holes left (so that the poured glue does not leak). To give it a round shape, the tape should be slightly warmed (you can use a lighter).
Next, we begin the restoration of the speaker suspension. Take instant glue and spread it on the tape, try to do it as neatly and smoothly as possible. Make sure the glue sets evenly. Then you need to leave the head to dry.
The glue dries within 5-7 hours, and then turns into rubber. While the glue is drying, the head must be placed on a flat surface so that the glue dries evenly over the entire length of the suspension.
After a few hours, the dynamic head is ready for use. There is almost no difference between the factory and homemade suspension, the sound is clear and high-quality, by the way, the client really liked it, I hope you like it too.
In general, for many years, almost the same technology was used to replace the suspension of dynamic heads of radio equipment S-30. These heads have a fairly high-quality sound, they 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. On 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 suited me - sometimes there was wheezing, then the speaker became very hard, then the alignment was disturbed and the varnish was peeled off the coil, but then I just decided to make a homemade suspension for such a head using tape and glue. 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, built 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 to a homemade suspension - don't skimp on the glue! The more you fill it, the better, and if you have dynamic heads at home with a worn-out suspension (this defect is very common), then don’t rush to throw them away, they will still serve you faithfully for several years! It is advisable to use super glue to pre-fix the tape. The dynamics parameters will not be affected by such an alteration, and the response to low frequencies will even be better than when the speaker was released from the factory - AKA.
Discuss the article SPEAKER REPAIR
Many music lovers are familiar with the situation: a loudspeaker installed in one of the speaker systems suddenly begins to “wheeze.” An external inspection reveals nothing; when ringing, the tester shows what is indicated on the label, but the sound is annoying, sometimes driving you crazy. This malfunction is especially typical for those with a large stroke. What's the matter?
A regular radio repair shop will advise you to simply replace the loudspeaker with a new one. This is a solution to the problem. It is simple but expensive. You can buy a good powerful head, and even a branded one, but it costs a lot. It will always be done in time. In the meantime, you can try to repair the speaker yourself.
As a rule, wheezing that occurs when playing the bass spectrum of sound frequencies is caused by short-term disruptions in the contacts connecting the coil to the speaker cable. In the place where thin, literally hair-like wires glued to the surface of the diffuser are connected to thicker elastic cables leading to the block, metal tin fatigue gradually accumulates during sound reproduction.
Repairing a subwoofer speaker, which most often suffers from this disease, is not difficult, but requires care. Usually the joint is filled with a drop of compound, so you need to pick it out very carefully, preheating it with a soldering iron. Once the connection is exposed, the contact should be soldered very carefully and quickly. After checking, if everything is in order, the repair area should be re-filled with an insulating compound, nail polish or viscous glue.
Speaker repair may also be necessary in cases where vintage or antique radio equipment over half a century old is being restored. For example, someone got an old American tube receiver from the post-war years. The condition is quite working, but the diffuser is badly damaged. You can, of course, simply replace the loudspeaker with a similar modern one. But you want to achieve “that” sound, to feel the time. In general, there is a desire to preserve as many of the original elements of the circuit as possible.
Repair of a speaker with a broken or torn cone is carried out using the gluing method. The best material used for applying such a “plaster” is. Scissors should be used to cut the patch so that it matches the shape of the missing fragment with an overlap of half a centimeter. Since rigidity is a good quality of a diffuser, it is best to glue the restorative part to it with acrylic nail polish. Where its edge adjoins the ring holder, rigidity, on the contrary, is inappropriate, the movement should be as free as possible, therefore it is recommended to restore the semicircular edge with rubber glue, like “eighty-eighth”. We can assume that the speaker repair is complete; all that remains is to let the varnish and glue harden and polymerize.
A common malfunction of loudspeakers is the wear and failure of the corrugated ring suspension, usually made of porous rubber and holding the diffuser along the edge. Repairing the speaker in this case involves removing the old one and gluing a new elastic ring. Kits for this procedure are sold, but it should be borne in mind that only expensive loudspeakers deserve such painstaking work; you shouldn’t bother with cheap ones.
