I like the old big, heavy speakers that were popular in the 90s. Despite their advanced age, they still sound pretty good and produce good bass. Recently I came across a pair of these speakers in a deplorable condition, but I decided to restore them and bring them back to life.
Professional repair of such speakers is very expensive, so it’s quite work equipment often they simply throw it away and buy modern subwoofers that are compact in size.
Will need
For proper repair Rubber or any other elastic gaskets of suitable diameter will be required. To accurately calculate right size spacers, you need to measure the outer diameter of the cardboard cone and the inner diameter of the steel frame, and based on this, look for spacers of the required diameter.
Restoration work
I recorded the entire speaker repair process with a camera. Below is a detailed photo report of all steps.The first step after removing the front panel is to remove the old seal and glue from the speaker circumference. To do this, I used a flat, sharp blade, but this must be done carefully so as not to damage the cardboard cone.
To center the cone while gluing it, you need access to the steel core. In large speakers, it is covered with a cardboard plug (it is glued), which must be carefully removed without damaging the cone. With cardboard plugs I managed to pry them off sharp knife, after which they came off along the adhesive connection, since they were not glued very tightly.
In small speakers, the dust caps turned out to be tightly glued, so they had to be carefully cut in a circle.
The next step is to accurately center the cone relative to the steel core. The free space between the cone and the core turned out to be different in each of the speakers. As an insulator and a kind of winding, I used strips of ordinary paper, which I pushed into the gap around the core until I achieved the most dense filling.
One of the small speakers required only one and a half turns of paper around the core, resulting in a slight displacement of the cone. Fortunately, in my case this circumstance did not affect the performance of the speaker, but I think that it would have been necessary to take thinner paper to complete two full turns.
For gluing rubber or foam seals, any household glue is suitable, for example, PVA or any similar one, which becomes transparent after drying. Glue is applied to the cone and speaker body along the edge of the hole, after which the gasket is carefully applied. You need to smooth it to the surface for a tighter fit and remove excess glue so as not to disturb the centering.
Once the glue has completely dried, you can remove the paper cup wrapped around the core. To check that the cone is properly balanced, lightly press it with your hand: it should vibrate freely without touching the steel core. If friction is present, all centering work should be redone and a new seal should be glued.
Now you need to install new damper pads around the speakers so that the front panel does not press or contact them. By the way, you can use old gaskets, completely free of glue, if they are in normal (not deformed) condition. The damper pad is glued to any glue. If the inner diameter of the new gasket is slightly smaller and covers rubber compressor(this may create interference), then it needs to be trimmed a little along the inner circumference so that the cone vibrates freely.
To glue the dust caps in place, I did the following:
- I glued a narrow and folded strip of tape to each cap. The result is a convenient loop so that you can move the semicircular part.
- I smeared the edges of the cap with glue.
- Carefully placed the cap in its place and applied a little pressure until the glue set.
Speaker breakdowns and methods for eliminating them
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Symptoms of malfunction |
Treatment methods |
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1. Doesn't play at all (no sound) |
The coil is burnt out or the wire is broken. Probably due to high power overload. |
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2.
The mobile system does not play and is destroyed |
In such cases, serious repairs are required. |
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3. The speaker (I apologize for the precision of the wording) “farts” |
There may be several options here: |
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4. If the speaker doesn’t “fart”, but “grinds” |
In principle, this is the same as step 3, but the effect is less pronounced |
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5. Extraneous sounds, but not constant, but only occasionally |
Probably dirt got into the gap (sawdust, for example) |
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6. Rattling sound, constant and throughout the entire frequency range |
Delamination of voice coil turns. |
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7. The same rattling sound, but only at one frequency (usually from 100 Hz to 1 kHz), something like resonance |
Something came loose in the moving system. It is necessary to check the adhesive joints on the cap, on the suspension, on the centering washer. |
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8. “Sniffling” or whistling sounds at high amplitude |
This is “noise” from air passing through the narrow gap gaps and into the holes on the diffuser, sealed with a cloth in the Riga speaker 75GDN-1. This cannot be cured, it is a design defect. |
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9. Yes, still... If he farts, but not constantly |
The coil came unglued from the diffuser... |
Repair for a slipped coil turn.
First, unsolder the flexible liner, then saturate the gasket and suspension (corrugation and lower centering washer made of fabric) of the diffuser along the diameter in the place where it is glued to the diffuser holder (silumin or steel basket) with solvent 646-648 (the solvent sometimes does not soften the glue, you can try xylene, toluene , benzene),
and wait for the glue to soften (from 10 to 20 minutes), when you can easily move the glued surface with your finger on the corrugation and the centering washer from the silumin diffuser holder. Carefully (DO NOT TEAR IT OFF! EVERYTHING SHOULD PULL AWAY BY ITSELF, otherwise you just poured too little solvent or waited too long) remove the diffuser from the diffuser holder. Place the coils coil by coil in place and secure thin layer BF-2 glue (it is possible, but worse, to use nitro glue) in particularly powerful heads, the coil is impregnated with a thin layer of epoxy glue. Reassemble in the reverse order, generously moistening all surfaces with solvent, thereby soaking the old glue again, put the diffuser in place, after centering the coil in the gap, begin gluing - pressing the fabric of the centering washer and the rubber (foam rubber - depending on the design of the head) corrugation to the silumin ( steel) surface of the diffuser holder into place. Center using rolled up film (for powerful heads, you can use rectangular pieces of thick cardboard, evenly distributed along the diameter of the gap, long enough for them to be easily removed from the gap after assembling the head), inserted into the gap of the core and voice coil (the cap for this is taken from the diffuser first carefully peel off, pouring solvent over the adhesive seam - make sure that the solvent does not get under the cap, otherwise the voice coil frame may peel off from the throat of the diffuser (This is exactly what happened to me: approx. Serzhi). When assembling, do not forget about the presence of a flexible connection to the coil, and do not glue past the coincidence of the coil terminals with the terminals on the diffuser holder. Using the same method, glue the gasket around the perimeter of the diffuser into place on top of the corrugation.
If there is a shortage of glue applied at the factory during assembly, glue STRICTLY with nitro glue such as Moment or Phoenix (those in large tubes) during assembly. This guarantees the ability to disassemble the head again for repairs, or in case of incorrect assembly (my old glue did not want to stick - I carefully dissolved and removed it and applied a thin layer of new one).
You need to pour a lot of solvent so that it stands and flows in the adhesive joints. You can slowly pour directly from the neck of the bottle (preferably, of course, from an oil can, which is made of chemical-resistant plastic). The solvent is toxic, don't poison yourself! He strongly rushes to the toilet after inhaling it - apparently his kidneys immediately remove the poison. Work in a ventilated place!
Protect the adhesive joints of the magnetic system itself and the center of the diffuser under the cap (glued voice coil frame) from solvent penetration, otherwise the head will fall apart. constituent elements. Apply only to the perimeter of the diffuser; carefully moisten the centering washer with a generously soaked cotton swab.
The main thing is CAREFULNESS! You can ruin everything, the paper is still there, crumple the coil frame and tear and crumple the diffuser, crumple and tear the cap.
In general, VERY GENTLE AND CAREFUL!
It is never necessary to unstick the magnetic system itself and it is unacceptable - the sensitivity (recoil) of the head may drop after gluing it again. For this reason, they are not always achieved good results in the repair of heads with a unglued magnetic system. You can glue a magnet to a core, but the magnetic force in the gap may decrease.
Rewinding a burnt out voice coil.
Carefully wind the burnt coil from the frame (if it doesn’t wind well, drop a drop of solvent), to facilitate winding and prevent the frame from collapsing, make a mandrel, which is discussed below. When winding, sketch where the beginning of the old coil was and how the terminals were sealed. Count the turns of the old coil. (Or look at the information on the speakers on this site. If it is not there yet, it will be soon :)) Select the wire exactly according to the diameter (you can measure it with a micrometer, and if you don’t have one, then wind 10 turns of wire on a suitable rod, measure the width of 10 turns with a caliper, and divide by 10) and carefully, turn to turn, wind it on a mandrel tightly inserted into the coil frame. The mandrel is made from slightly larger, relatively internal diameter coil frame, a piece of metal (preferably not too thick - it won’t compress) pipe with a longitudinal cut, so that when the mandrel is inserted into the frame, the pipe can be compressed, and then it will straighten out and press the frame tightly from the inside. You can make a cut in the pipe with a hacksaw. Take the pipe of such length that it is convenient to squeeze the free end when putting the frame on it. Wind the first turn according to the beginning of winding the old coil (as a rule, the first turn is located at the neck of the diffuser and is soldered directly to the contact rivet). Secure the first turn with thread, which is removed after winding. When winding, sometimes rotate the diffuser with the coil on the mandrel to prevent the frame from sticking on the mandrel. The tension during winding is not strong - otherwise you can compress the frame together with the mandrel (for this reason, it is sometimes useful to wedge a split mandrel from the inside by inserting a suitable wire into the cut or a hard object inside the pipe). When winding, you impregnate the first layer with liquid glue - an extremely thin layer. Handle the wire gently, otherwise you may tear off the varnish insulation. After winding the coil, saturate it (in a thin layer) with liquid BF-2 glue - diluted with alcohol (epoxy - diluted with nitro solvent 646-648), tin the leads with rosin and solder them to the contact rivets. When soldering, the use of acid and acid-containing fluxes is unacceptable, only rosin!
How to try to straighten a jammed cap.
Try to peel it off carefully - generously watering the gluing perimeter with nitro solvent 646-648 (or another - see above). After peeling off, lightly moisten it with water and firmly clamp it in a vice, selecting a punch and a matrix of a suitable convex shape for it. (my finger just straightened out - it was dented a little) After several days of exposure in a vice, process inner side very liquid epoxy glue, diluted with nitro solvent - a very thin layer!
Wait until it sets completely (liquefied epoxy can take more than 3 days to dry), then carefully glue it in place with “MOMENT” type nitro glue - the one that comes in large tubes.
Although in theory, such a head should of course be replaced with a new one.
When pressing the cap on the tweeter or midrange, you can try to stick tape on it and quickly pull it towards you. Must straighten up.
How to remove metal filings from a magnetic gap.
Very often, when disassembling heads, it is found in their magnetic gaps a large number of metal filings and pieces of magnet. They are removed by holding a piece of adhesive tape (insulating tape) folded in half in the gap, sticky layer out. Some experts recommend pouring rubber glue into the gap, and after it dries, pull it out of the gap along with the sawdust. I haven’t tried it myself, and I can say that this method is most likely not suitable for many gaps in which there are free cavities between the ring magnet and the core washer and the diffuser holder flange (almost all low-frequency and broadband heads high power with a ferrite-barium ring magnet). For those heads in which there are no such cavities, and the gap is an even longitudinal slot in depth, this method is probably possible.
A little trick.
If the coil touches, sometimes this is due to the diffuser sagging downwards due to the old age of the head. Then you can try to change its position in the column - turn the bottom of the speaker up 180 degrees in the column panel. Then if the coil has not flown off, but is simply touching it due to the diffuser sagging over time, then the sagging may be compensated.
Sometimes a hitting coil can be cured by creating an opposite distortion of the diffuser using an insert into the diffuser holder (rag, foam rubber). Leave the head in this position for several weeks, and perhaps the misalignment after removing the insert will be compensated.
Unfortunately, these tricks rarely help, and you have to disassemble the head.
The principle of the electrodynamic GG device is shown in Fig. 1.
Fig 1. The device of the electrodynamic head of the loudspeaker / - diffuser holder, 2 - movable system 1, 3-magnetic circuit
The loudspeaker head consists of three main parts - a magnetic circuit 3, a moving system 2 and a diffuser holder 1.
The magnetic circuit of the GG can be made in two versions: shielded or unshielded, depending on the requirements for the equipment in which the GG is used. Various options shielded core, ring with cast magnets and ring with additional shield and unshielded circuits are shown in Fig. 2.
Fig 2. Design of the magnetic circuit of the loudspeaker head a - shielded circuit with a core magnet, b - unshielded circuit with a ring magnet, c - circuit with a ring magnet and an external screen, 1 - core, 2 - upper flange, 3 - permanent magnet, 4 - lower flange ( or glass), 5 - screen, 6 - tip
The magnetic circuit of the GG consists of elements of the magnetic circuit of the upper flange 2, cup 4, core 1 and permanent magnet 3 with tip 6 (Fig. 2.a) or the upper and lower flanges 2 and 4, core 1 and permanent magnet 3 (Fig. 2 , b). Sometimes it is placed in a shielding glass (Fig. 2,c). Constant magnetic flux, created by a magnet using magnetic flanges and a core, is directed into the air working gap, which has the form of an annular cylindrical slot between the core and the upper flange
Ring ferrite-barium magnets (25BA170, 28RA180) are usually used as permanent magnets in unshielded circuits; in shielded ones, cast cobalt-containing (YN13DK24) or rare-earth magnets are used. For the manufacture of magnetic circuit parts, mild electrical or structural steel is usually used (Art. 10)
The efficiency of the GG as an electromechanical converter is characterized by the product of induction magnetic field in the gap on the length of the conductor (i.e., the length of the voice coil wire) The magnitude of induction and the structure of the magnetic field distribution are affected by the width and height of the working gap, the configuration of the flanges and core, as well as the volume and width of the permanent magnet.
Fig 3. Design of the moving head system
loudspeaker a - with a conical diffuser, b - with a dome diaphragm,
1 - voice coil 2 - centering washer, 3 - flexible leads, 4 -
suspension, 5 - diffuser (diaphragm), 6 - dust cap
Figure 3 shows the mobile GG system. It includes suspension 4, cone diffuser or dome diaphragm 5, centering washer 2, dust cap 6, voice coil 1, flexible leads 3.
Suspension 4 has the form of a corrugated annular shell, which has great flexibility in the axial direction, which allows the diffuser to perform axial vibrations with a large displacement amplitude. The suspension is cast together with the diaphragm from paper pulp or made from special soft materials(rubber, polyurethane foam, etc.)
The diaphragm (diffuser) 5 is an elastic shell of rotation (conical, dome or flat), which oscillates under the action of an axial mechanical force from the coil, exciting vibrations in the air environment and emitting sound. Currently, most GGs use diffusers made of natural cellulose materials with a successful combination physical and mechanical parameters. IN last years used as materials for diaphragms (diffusers) are polymer, honeycomb, metal and composite materials.
Centering washer 2 is a corrugated membrane that ensures centering of the voice coil in the gap, prevents the occurrence of circular vibrations, allowing the diaphragm to make large displacements in the axial direction. Centering washers are usually made of cotton fabric, cambric or chiffon, impregnated with bakelite varnish.
Dust cap 6 is a dome or flat membrane that protects the gap from dust, acting as an additional stiffener on the diaphragm. It is usually made from paper pulp, fabric or metal foil.
Voice coil 1 is a cylindrical frame with an insulated conductor wound in several layers. As a rule, the number of layers of the voice coil is even, so that its leads come out in one direction. When an alternating current magnetic circuit flows through a voice coil placed in a radial cylindrical gap, a mechanical force will act on it, under the influence of which vibrations of the voice coil and the associated diaphragm occur. The coil frame is usually made of cable paper or metal foil; copper or aluminum wire in enamel insulation is used as a conductor.
Flexible leads 3 connect the voice coil conductor to the output connecting terminals GG.
The diffuser holder serves to connect the magnetic circuit, the moving GG system and provides fastening in the housing of the equipment where it is used. The diffuser holder is usually made by stamping from steel or by casting from silumin.
All elements of the moving system and magnetic circuit have a significant impact on the electroacoustic characteristics and sound quality of the GG.
Disassembling and assembling the speaker
First, the patient's flexible lead wires were unsoldered (from the side of the contact pads)
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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... |
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Place where the centering washer is glued to the diffuser (along the perimeter)... |
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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) |
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Attention! When working with solvent, safety precautions should be observed - avoid contact with skin (work in 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! |
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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! |
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After peeling off the cap, carefully pour out the remaining solvent from the recess near the coil mandrel (by turning the patient over). |
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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. |
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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!!!) |
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We clean the gluing areas from old glue and dry the disassembled speaker. |
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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. |
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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 cut off the supply wires at the break point... |
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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? ;), |
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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. |
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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 preserve the length. |
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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. |
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Glue the diffuser. We use the indication for the glue used (I recommend “Moment”, main criterion choice 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!)... |
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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. |
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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 appearance dynamics. 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. |
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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 the 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.
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's clear, high power you won’t achieve the device, for playback purposes high frequencies Speaker systems speaker is suitable. The main advantage of the technical solution is 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. Need to get 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 configure the electronic part correctly: 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 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.
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 produced 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 the 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.
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 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 save as much as possible original elements scheme.
Repair of a speaker with a broken or torn cone is carried out using the gluing method. The best material, which serves to apply such a “plaster”, is Scissors should cut the patch so that it matches the shape of the missing fragment with an overlap of half a centimeter. Since rigidity is good quality diffuser, then it is best to glue the restoration part to it acrylic varnish for nails. 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.