Acoustic systems are divided into active and 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 has similar functionality to a player. Let's look at what to do when the speakers don't work. Speakers include a myriad of sound reproduction devices; readers are interested in how to repair speaker systems with your own hands. You will need special glue. When the USSR was in use, BF 4, AK 20. Solvents were selected accordingly (based on the glue). You will need to disassemble, dismantle the connection, and repair the speaker system yourself.
The structure of a typical acoustic speaker
A moving part with a rigid plate creates air vibrations that are perceived by the human ear.
Classification of acoustic speakers
Carry out repairs speaker systems with your own hands, doubting how the device works, you rely, using the principle - do no harm. Regardless of the size, the speaker of the acoustic system is formed by electrical and mechanical parts. The first is formed mainly by inductors. The second includes a permanent magnet and a membrane. Here is an incomplete classification of speakers for acoustic systems.
- Electrodynamic playback devices form three classes, united by the concept of the presence of a magnet and a moving membrane:
- Reel machines are built according to a principle known to the owners (repairers) geysers. When the inductor voltage is applied, the magnetic ring causes the membrane to move according to the law of the applied audio frequency current.
- In strip magnets, the role of an alternating magnet is played by a narrow corrugation. No coil, of course, inside. Speaker applications require matching transformers. A sign identifying the type of speaker of the speaker system.
- Isodynamic loudspeakers include a square, round spiral that moves parallel to the membrane in the field of a permanent magnet.
- Electrostatic playback devices have no moving parts. The membrane vibrates without making translational movements. The speakers reproduce high frequencies perfectly due to their low inertia.
- Piezoceramic speakers exploit the effect of converting electricity into vibrations of a quartz crystal. It is clear that you will not achieve high power from the device; the speaker is suitable for reproducing high frequencies of acoustic systems. Main advantage technical solution in low energy consumption.
- Ion speakers are practically rare; the theory was developed in the 50s. The operating principle is based on the modulation of gas ions by sound vibrations. It is necessary to obtain an electric arc. Ideas have been put forward to use flames formed by positive and negative particles (air ions).
Readers are familiar with naturally occurring sound-reproducing devices. There is not always an inductor in the dynamics of an acoustic system. Therefore, before repairing, in the process, the technician carries out the correct classification of the devices by properly carrying out the necessary operations.
The device of the speakers of the acoustic system
Partially touched the device. Let's take a closer look at electrodynamic models. The diffuser forms the support of the cap. It is represented by something like a wide horn onto which a coil is glued on the reverse side. Flexible copper conductors carrying electricity, breaking through the diffuser from the inside. The soldering points are visible from the front of the speaker. The coil is light, it is required to ensure a relatively low inertia of the system. Even the tuning fork A of the first octave lies at a frequency of 440 Hz. It is clear that for fluctuations of the specified speed, the moving part of the acoustic speaker must be light.
The magnet is mounted motionless on the frame. Usually circular. An inductor runs in the hole in both directions, moving the cap-membrane assembly. The connecting wires perform constant oscillations. To position the moving part along the vertical and horizontal axis, a centering washer is used. A perforated piece of elastic material that centers 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, the matter is to check electrical installation, places where wires are soldered, integrity of the coil.
The inductance is wound in the same way as the old one. Each layer of turns is coated with BF 4 glue. Poor-quality soldering is done again. Select the appropriate winding method and inductance. Usually done special device, formed by two pairs of posts standing opposite each other on a long board. Both are connected by axes. One contains the core of the new coil, the other contains the purchased wire. It is recommended to buy wire with varnish insulation. It is necessary to maintain the correct thickness. You can measure using a caliper.
Winding is carried out relatively quickly while the glue dries. The coils fit tightly one to the other, following the shuttle principle. It is important to maintain the correct number of revolutions and properly position the terminals.
Often you have to disassemble the speaker of an acoustic system for repairs. Stock up on solvent. The glued joints are wetted and a fixed time is waited. Please note: the joints are carefully cleaned. This is done regardless of the glue used to assemble the speaker of the speaker system.
Speaker range
Speakers for acoustic systems different types, each has a limited range of reproduced frequencies. Each one 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. A 5–10% solution of TsAPON and cellulose in acetone are used. The varnish is applied with a soft brush in a circle. Avoid misaligning the moving part of the speaker system. By performing the operations sequentially, we will increase the resonance frequencies by 1.5–2 times, approximately one octave.
To reduce the range, you should stick weights on the moving part. The correct ring of cardboard is attached to the back of the diffuser. The symmetry of the arrangement of parts should be more accurately maintained. The sound pressure drops rapidly. The volume decreases, the range of high frequencies narrows. However, in the resonance region, the speaker of the speaker system will demonstrate good performance.
The range can be expanded in both directions (if there is no cap). In the center, from the front, above the inductor coil of the speaker of the acoustic system, a truncated cone is glued. The mass is made as small as possible. Thin, thick paper impregnated with TsAPON varnish will do. The upper platform is equal to the coil, the height is half the diffuser, the taper is 70 degrees. Due to the increase in mass of the moving part, the resonant frequency drops, but the upper end of the range rises, thanks to the rigid core, harder than the diffuser. As a result, the spectrum of reproduced sounds expands in both directions. The total increase will be one and a half to two octaves, the game is worth the candle. Take care to set it up correctly electronic part: if there are passive filters on capacitors and resistors, they will limit (cut off) the capabilities of the mechanics.
Masters Promote sound pressure at the resonant frequency for an unshielded magnetic system. Try to find this or a similar ring installed. Then glue the second magnet onto reverse side standing, the interaction of fields will intensify, therefore, the strength of sound will increase.
The design of the acoustic system is simple, but it can break, they said. We hope the renovation goes off without a hitch.
Probably every radio amateur, and not only radio amateurs, has burnt speakers at home. This can happen to anyone. Breakdown of output transistors, overload, or manufacturing defects and much more can lead to failure of the coil inside the speaker. I want to tell you about my case. Dynamic head 25GDN-3-4.
She left us, going into the world of spirits, while listening to hard rock :) She left beautifully. At first she began to wheeze heavily, and then thick and stinking smoke poured out of her. The dust protection cap has melted. After disassembly, it turned out that half the coil had also burned out.
It is not difficult to rewind it, but the work requires patience. I only managed to wind the reel the second time. So, let's start repairing the speaker.
Stage 1 - collection of information. In reference books or on the Internet. You need to find data about the speaker itself, and especially about the coil. It will have to be made from scratch. Dynamic head specifications:
— Effective operating frequency range — 50 — 5000 Hz
— Level of characteristic sensitivity — 84 dB/W*m
— Frequency response unevenness — 14 dB
— Total harmonic distortion — 3 — 6%
— Nominal electrical resistance — 4 Ohms
— Maximum noise (nameplate) power — 25 W
— Limit long-term power — 30 W
— Maximum short-term power — 70 W
— Main resonance frequency — 55 ±10 Hz
— Equivalent volume — 8 Vas Liter
— Total quality factor — 0.5 ±0.5 Qts
— Diffuser diameter — 110 mm
— Magnet dimensions — d110x16 mm
- Are common dimensions— d125x79 mm (my measurements — d125x73 mm)
— Weight — 2000 g
— OST 4.383001-85
And the speaker coil data:
— Wire brand — PETV-1
— Wire diameter — 0.224 mm
— Number of winding layers — 2
— Number of turns in the 1st layer — 47
— Number of turns in the 2nd layer — 46
— Ohmic resistance — 3.1 ±0.4 Ohm
— Voice coil height — 22.5 mm
— Internal diameter — 25.4 mm
— External diameter, including winding — 26.6 mm
There is information. We select the required wire diameter and move on to the second stage.
Stage 2 – disassembling the speaker. We unsolder the multi-core wires going from the coil to the speaker terminals. For disassembly we need a solvent, a brush and a plastic bag. Solvent for paints. It said 647 on the can. I bought it at a store that sells auto enamels. We need to use it to dissolve the glue that glues the speaker together. To do this, use a brush dipped in solvent to coat the edges of the speaker. And also at the bottom there is a linen centering washer, also along the edges where it is glued. The dust cap also needs to be peeled off. But I didn’t keep it. After impregnation, put the speaker in a plastic bag and tie it. This is so that the solvent does not evaporate so quickly. We wait about ten minutes. Let's take it out and look. The glue should have dissolved. The diffuser can be removed from above by hand, and the membrane from below must be pryed off with a knife or scalpel. If it lags behind heavily, then we repeat the procedure with the solvent and the bag. All work with solvent and glue must be carried out outdoors. I did it on the balcony. I hope everything worked out.
Stage 3 – winding a new coil. For this we need thin and thick paper. As you can see, the height of the coil is 22.5 mm. I cut a strip 300mm long and 22.5mm high. Picked up the phone required diameter. The diameter can be adjusted by wrapping several turns of electrical tape around it. I measured it with a caliper. I wrapped the paper around the tube, coating each turn with glue or varnish. I used glue brand 505. It dries quickly and then becomes hard. It seems to withstand the temperature. Having removed the learned ring from the tube, we measure how it fits into the speaker core. It should go in and out easily with a small gap. If everything is fine, then we put it on the tube again and start winding the wire. Winding in two layers. The first layer is 47, and the second is 46 turns. Lay the coils one to one. The first turn must be secured with glue or varnish. After winding the first layer, soak it with glue. Next is the second layer, and again with glue. After drying, remove the coil from the tube and measure how it fits into the core. It should go in and out easily. If it rubs somewhere, or doesn’t fit at all, we redo it again.
Stage 4 – assembly. We glue the wound coil to the diffuser. You need to try as smoothly as possible. This time you need to use glue that can be dissolved. Suddenly it will need to be disassembled again. To do this, I bought glue for gluing rubber. We solder the coil wiring to the multi-core wires on the diffuser.
The coil with the speaker core needs to be centered using a piece of photographic film or thin plastic. Let's connect. We smooth the linen membrane with a knife or some flat object. To securely fasten the diffuser to the frame, we screw the speaker to a flat surface with self-tapping screws.
We solder the stranded wire to the speaker terminals and wait several hours.
Stage 5 – speaker tests. Unscrew it from the board. We take out the film from the core. By pressing the diffuser with your fingers, we listen to see if there is any friction in the coil. If it jams, then return to step 2. Check the coil resistance with an ohmmeter. Everything is okay? Then we connect it to the amplifier and listen. A properly assembled speaker will sound like new. If there is a slight friction between the spool paper and the core, it should go away over time. In case of friction of the coil wire with the outer iron washer - definitely stage 2. If the tests went well, then glue the dust cap. In my version, I peeled it off with a solvent from another speaker.
As you can see, there is nothing complicated. I think that it would not be advisable to rewind low-power small speakers. But it depends on your desire. Perhaps something can be simplified or done better. Happy rewinding everyone. The speaker was repaired - Boozer.
Previously, we have already addressed the topic of repairing car dynamic heads or, simply put, repairing a speaker with your own hands. Then we considered a method of restoring the head suspension using ordinary silicone. But we also encounter problems of a more serious nature. That is why today we decided to focus on such a common problem as misalignment.
Naturally, today everyone knows what a dynamic head consists of. Yes, it contains a signal electric type is converted into membrane movement and spreads through the air.
At the time when the same signal is focused on the coil, a magnetic field is formed that interacts with the magnet. And due to the fact that this signal is temporary, the coil begins to vibrate, as if running away from the field. However, the coil has nowhere to run and begins to transmit this signal to the diffuser, which in turn transmits it into the air, producing sound. Naturally, this process is transferred in simple words, and he's on technical terms will sound completely different. But the essence itself is important.
An iron core is used here to direct the field. In turn, this core is attached to a permanent magnet. It is a round disc-type iron platform with a sleeve in the center, which consists of a voice coil. In order for this coil to move easily, there is a special gap in the middle of the magnet and the core. And due to some unfavorable factors, the glue that connects the disk to the magnet weakens and the core crushes the coil, which leads to immobility of the diffuser. The speakers may work, but you won't be able to hear any bass.
How to get out of this difficult situation? And is it possible to make the speakers return to their normal state? This is exactly what will be discussed later in the article. So, in the situation that I encountered, the speaker mount was broken, and because of this, I immediately started with the centering washer. It happens that in speakers the same centering washer is attached with very weak glue.
Therefore, in order to separate the washer, you just need to moisten the junction of the chassis with it with simple acetone and wait a couple of seconds. And in some cases, acetone alone is not enough. Most often this concerns high-quality speakers, where strong and high-quality glue is used to attach the washer and chassis. Here you need to resort to real vandalism. Namely, it is necessary stationery knife cut off the washer and wires coming from the voice coil towards the speakers. 
Next you need to disconnect the diffuser.
At the end of these manipulations, it becomes clear that the core sticks to the magnet and needs to be put in its place, namely in the center. However, it is worth noting that this is not at all easy to do, because here you need to work with iron and a permanent magnet.
They interact extremely reliably with each other, and it will be difficult for you to place the core in the center. It is important to understand that the voice coil is completely attached to the diffuser and is crushed. Therefore, you need to tighten the diffuser itself. After freeing the coil, you need to carefully inspect it.
If the varnish that covers its wire is damaged or the coil itself is dented, additional reconstruction of the coil is also required.
To repair the coil, the first thing you need to do is look for metal sheets, the thickness of which is half a centimeter.
These sheets need to be attached between the core and the magnet. In general, we need to fill all the space that the coil occupies. 
In this case, each plate must be inserted evenly so that the distance is equal on each side.
After all this, you need to glue the magnet to the washer holding the core itself. Best to use for this good glue by type of moment.
You can also take epoxy for these purposes, but here you need to mix it with sawdust or pieces of fabric for greater reliability.
Then, after the glue has hardened, you can remove all the plates and put the entire speaker back together.
The suspension and centering washer sit on the same glue. In this case, it is also possible to additionally repair the suspension.
In this way, you can repair heads of various types.
And I also want to note one point: if you decide to sell your car and don’t know where to start, just call the Center-Auto company, which will buy your car. Even if it is after an accident, contact and receive money on the same day.
You can often come across requests for help in repairing and rewinding the coils of burnt-out speakers; articles on this topic have been on the Internet for a long time, but we decided to make our own. So, I got my hands on a burnt-out Pioneer subwoofer speaker from a TS-WX303 subwoofer; the rated power of the speaker is about 250 Watts. It seems to me that the former owner went too far with the power and as a result our speaker burned out.
When you press the diffuser, a clearly audible grinding sound is produced, this is the coil rubbing against the magnetic core, possibly falling apart, after disassembling the speaker everything will become clear. The main difficulty is to disassemble the speaker, because it is very important not to damage the speaker suspension, it’s good when the suspensions are rubber, such ones come off and come off with a bang, in the case of foam rubber and their analogues, everything is not as simple as it might seem at first glance.
So, a photo of my patient:
Personally, I disassemble speakers in one of two ways, thin blade, or by soaking in a solvent. In the second case, you need to work strictly outside or in a well-ventilated area, but not at home or in the entrance. You need to prepare in advance all the tools necessary for repairs, perhaps primary tools for dismantling the suspension and centering washer. The centering washer is located under the diffuser, usually yellow color made of thick pressed mesh fabric.
For soaking, you can use a syringe, draw the solvent into the syringe and carefully spray the outer parts of the suspension, in the place where it is glued to the “basket”. Soaking usually takes a long time; in 5 minutes you will not separate the suspension from the speaker body. The centering washer is soaked in exactly the same way.
This is not the first time I have rewinded speakers, and the dismantling operation for this speaker took me about 5-7 minutes. After soaking, we unsolder the conductive wires from the terminals and remove the diffuser with the coil from the frame. In principle, it is possible and necessary to unsolder the wires before soaking, it will be more convenient... We look at the photo of the coil of my burnt speaker:
The photo clearly shows overheated and charred turns of copper wire; this coil will have to be unwinded completely and rewound again. Some unscrupulous repairmen practice the following type of repair: they unwind part of the burnt wire and connect the break points together by soldering. Naturally, such a “homeless repair” will not last long; in addition, after unwinding some of the turns from the coil, it will noticeably reduce the total resistance of the speaker, which will certainly affect the power.
In general, if the coil is more or less alive, you can leave it, after soaking the coil with varnish, it will last - but not for long. This option is applicable for beginners, for those who are afraid to rewind the coil due to certain circumstances (for example, there is no necessary wire for rewinding).
Ideally, the speaker coil should be wound with BF-2 glue. It's not easy to find, but it's the most the best option. We glue the suspension rubber glue 88, it is usually sold in small jars in construction stores, this glue is used to glue carpets onto subwoofers:
Finding the right wire is also a problem, good wire donors are contactor (starter) coils, which are sold separately in electrical equipment stores and are not expensive, this is exactly the wire I use. The required wire can also be found in the demagnetization loop of picture tubes (CRT), a sample of my wire for winding is shown below in the photo:
I removed this wire and rewound it just from the starter, the diameter of the wire is approximately 0.35, by the way, it’s too much to rewind thin wire not recommended because The speaker power will drop sharply. If you take a wire thinner than it was, then you will have to make a little more turns than there were, otherwise the resistance of the speaker will be less.
You need to wind the wire turn by turn, winding a speaker is a delicate and labor-intensive task, the main thing is not to abandon everything halfway... I wound it with a wire of approximately the same cross-section, I got 4 layers in total, covered each layer with BF-2 glue and let it dry for about two hours. Determining the required length of a new wire with sufficient accuracy is not so difficult; you need to calculate the length of one turn (knowing its radius), multiply by the number of turns in the layer and the number of layers. My speaker required about 20 meters of enamel wire. The diameter of the wire is determined using a micrometer or caliper. For winding, it is better to use a specialized machine, which greatly simplifies the entire winding process; if you don’t have such a machine, you will have to wind the coil manually.
After the glue has dried, we begin to assemble the speaker. I note that gluing the centering washer and the suspension at the same time is highly not recommended, because with a 99% probability, after the glue dries, your speaker will groan. First you need to glue either the centering washer or the suspension (I glue the first). That is, we coat the edges of the washer and the gluing points on the speaker body with a brush, let it dry a little and carefully put the diffuser on the body so that the coil does not rub against the magnetic core.
It will be difficult the first time, so you can coat the washer with glue not entirely, but only at several points; if centering is successful, you can re-glue it.Next, we glue the suspension; when connecting the suspension to the speaker basket, you need to center the suspension itself in parallel, so that there are no rustling or grinding noises when the diffuser moves. Then we solder the conductive copper wires (conductors) going from the coil to the speaker terminals and let the speaker dry for 24 hours.
There is another, more accurate option for centering the coil, but to do this you will have to remove the cap from the diffuser. After removing the cap, we put the diffuser and coil in the basket, then take A4 paper, cut it along the wide side lengthwise into two halves and roll it into a tube of approximately the same diameter as the core of our speaker and carefully insert it into the gap between the core and the coil, then You can safely glue the centering washer with the suspension. After the glue has dried, pull out the paper and glue the cap back on.
Most dynamic heads are not intended for disassembly and are, as it were, disposable (non-separable, difficult to repair) components of speaker systems. In practice, it is successful to disassemble the speaker standard design and it is often possible to reassemble it. The main task is to soften the glue that holds many components dynamics, and separating them from each other without injury or deformation.
If you have questions about rewinding speakers, ask them here, we will try to help!
