Restoration of fabric suspensions of acoustics. Restoration of fabric acoustic suspensions Impregnation for paper full-range speakers

Diffuser impregnation

WITHThe best diffusers are paper diffusers. Paper is filled with natural fibers of fabric, wool, but this does not apply to dynamic heads ex -USSR as well as today's China - here we have paper in its purest form. Moreover, if in the USSR the speakers were "invented" (copied and developed trophy German developments) nevertheless clever people and most of the speakers were made with diffusers having an exponential generatrix, then the Chinese speakers for the most part are cones. The cone diffuser oscillates very well on its own, creating a veritable pick / dip in the frequency response and greatly distorting the phase response of the head. To reduce the intrinsic resonances in the diffuser, we have one way - to give different parts of the diffuser (along the path of propagation of sound vibrations in it) different coefficients of internal friction in the material. Those. it is necessary to create a stiffness gradient of the diffuser in the direction from the center (excitation source - voice coil) to the edges (corrugation).

Good results (believe me, damaged more than one speaker while trying to repeatability) were obtained with the following work technology:

1. We mentally divide the diffuser into three concentric parts: center, middle, edge by 1/3 SQUARE of the surface. The inner part - the center is focused on the radiation of high frequencies, therefore it must be rigid. The middle part - the ring should not resonate at medium frequencies, therefore it must be impregnated with a viscous composition. The edge of the diffuser, including the corrugation, is responsible for the flexibility of the suspension and also for the absence of resonance phenomena, so the mass of the impregnation should be greater than the mass of this section of the paper.
2. Preparing solutions for impregnation. For the central part, finely crumble the remains of a broken case from a compact cassette or CD (transparent plastic) and dissolve in a vial with dichloroethane. It will take a week or two and a warm place, shake the bottle once a day. For the middle part, the solution can be prepared before carrying out work in the required amount: dissolve synthetic rubber glue in a ratio of 1: 4 in white spirit, mix well (shake the closed vial vigorously 20-30 times, wait for all air bubbles to rise). For the extreme part, Tectyl automotive sealant (spray) for internal cavities, yellow, liquid, is suitable. Immediately before applying, we decant the required amount into a jar, for example, into a glass from Kodak film, defend a little and go straight to business.
3. Apply the compositions to the appropriate areas of the diffuser with three different soft brushes, starting from the center. Very carefully, avoiding drops, they stretch the strokes along the outer surface of the diffuser, visually controlling the "juiciness" and uniformity of the layer application. Thus, 2 layers of each composition are applied with intermediate drying between layers of one coating for 3-4 minutes and 10-15 minutes between the areas of impregnation with different compositions. The compositions have a very strong penetrating ability through the pores of the paper, therefore they are very quickly absorbed completely, literally in a minute already it is possible to make a mistake which section has already been processed and which one is not.
4. As a result of processing, the diffuser does not change its presentation, no gloss or smudges are formed, but the physical characteristics of the areas become completely different... This reduces the likelihood of resonances on the surface of the diffuser with a wavelength multiple of the radius, effective speaker diameter and their derived dimensions.
5. We dry the speaker away from the heating batteries for a month (it is better to put it on the cabinet with a magnet downward, and close the speaker with a piece of paper from the top of the dust). The first turn on is training. We check the absence of signs of rattling and develop a corrugation by feeding a sinusoidal signal of a low (but not resonant frequency, but either 0.8 or 1.25 of it) to the speaker, we train the free travel of the diffuser 0.5-0.7 from the maximum for 1-2 hours ... For example, I put a working speaker in a box and covered it with two warm blankets on top to make it quieter. After that, the speaker can be installed in the column and the frequency response / phase response can be measured.

If none of the solutions are absorbed well i.e. without a trace, then your speaker is already saturated with something and you will no longer be able to "help" it in this way. If this has already been done by someone before you, and it is crooked (homogeneous impregnation) - it is better to replace the speaker with another one.

In this way, both LF and MF and HF heads are impregnated, in the latter case, you can break (mentally, of course!) The diffuser not into three, but into two zones and do not use Tectyl.

P.S.Nottry to apply silicone coating to diffusers, formulations based on castor and mineral oils, natural fats, bitumen, creams, petrolatum, alcohol solutions, based on BF, PVA adhesives - it's useless, it has been checked: the results are either zero or bad or the appearance deteriorates.

Accidentally discovered by an amateur car audio enthusiast, the hidden functions of a liquid known as a "tire restorer" make it possible to radically improve the sound of inexpensive car audio systems, invigorate elderly speakers, almost giving a second life! So, in any case, say the adherents of the popular among the people "theory of impregnation of suspensions" ... What is this - a useful life hack with an instant result or mass self-hypnosis?

Our portal, of course, tries to tell its readers primarily about proven and proven technologies applied to the automotive field, but some things on the verge of science and superstition are becoming so popular in the auto world that their fame goes far beyond the chatter in social networks and garages. "A technique to improve the sound of car audio systems in five minutes" is one of those things. Let everyone find something of their own in this story: a professional - a chance to smile, an amateur to put his hands on - a reason to dig deeper into the car on a weekend, curious - food for the mind. So let's go!

- I am an electronics engineer by education, at one time I worked for a long time at the Saransk precision instrument plant. Now I am engaged in the trade of audio components and consulting in the field of sound - Igor told Kolesam.

- About ten years ago I got into my hands a bottle of Doctor Wax "tire restorer", with which I tried to process various rubber parts your car. The tool worked very well: the lifespan of the rubber bands of the muffler suspensions, silent blocks and anti-roll bar cushions, destroyed by salt and temperature, increased. I'm not talking about the fact that the door seals began to fit better. As a result, an interest arose to try to improve the characteristics of the suspensions of some old speakers with the help of the same composition. The effect was simply stunning - five minutes after applying the composition with a brush to the suspension of the diffuser, the sound of most speakers improved so that it is noticeable to anyone, not just an "audiophile with trained ears"!

- Actually, the key essence of the technology is to return the factory characteristics to the dynamics, Igor continues.

- At one time, I regularly attended the annual Hi-Fi-Show in Moscow, where I talked with representatives of well-known foreign audio manufacturers: DLS, Jamo, etc. And they did not hide how quickly the suspension of the new speaker loses its elasticity. Six months - and the characteristics are no longer the same as immediately after the conveyor. Engineers know about this fact, try to take it into account when designing to compensate for aging, but it turns out only partially ... But the "tire restorer" does an excellent job, it softens the suspension and prevents further drying out for years! At the same Hi-Fi-Show, I repeatedly suggested to many manufacturers of high-quality acoustics to check the effect of impregnation. Most, of course, twisted their fingers at their temples, but some agreed and were pleasantly shocked: literally five minutes after the impregnation, the acoustics began to sound noticeably better. Over and over again, the wires were switched from processed to unprocessed speakers, and the difference in favor of the processed was obvious!

According to Igor Bobrov, having made sure of the clear positive effect, he repeatedly turned to the Russian representative office of the tire restorer manufacturer, offering them his idea for a moderate reward - to use the discovered “ easter egg”And start selling the same liquid under your own brand in a small package with a brush. But not as a tire restorer, but as a specialized tool for the restoration and improvement of acoustics. Igor's office listened attentively, promised to transfer the information to the foreign office, and everything went well and died out ...

Results of impregnating speaker suspensions with tire restoration fluid

Igor Bobrov has been promoting on the Internet the technology of impregnating suspensions with a liquid to protect and restore tires for almost ten years, emphasizing that he does not have a penny from this. During this time, hundreds, if not thousands, of people followed his advice, processing the speakers of car and home audio systems.

Here are typical responses from tech converts:

“… I was stunned! In his old woman he smeared the "cadences", the hard cadence bass became velvety, deep, the sound became multi-storey, layered! Now in my gut I feel the lows, mids and highs. I wanted to change the speakers. Thanks!…"
“… Processed car speakers Morel Tempo 6 - the sound has become much juicier! ... "
"... I tried it on old Soviet speakers 25GD-26B, I achieved a decrease in the resonant frequency from 46 Hz to 32 Hz ..."

However, few people measure the parameters of the speaker before and after processing. For example, such as resonant frequency, quality factor, amplitude-frequency characteristic. Almost all who have tried the "technology" evaluate the result subjectively, by ear.

The fact is that Igor himself deliberately neglects numerical data and measurements, claiming that "everything is heard with the ears."

"Take it and do it - it's still simple and inexpensive, stop wagging your tongue on the Internet!" - this is, in general terms, his position.

However, supporters of the scientific approach are outraged, and they can be understood ...

We did not conduct a deep and comprehensive study of the technology, however, in order to form our own impression, we did two simple tests - subjective and objective. Objective - measurement of the resonant frequency of the speaker before and after impregnation of the suspension. Subjective - listening to impregnated acoustics - also before and after. Actually, it is the subjective method that the author of the idea promotes. "

You will hear everything with your ears, it is much better than measurements and obtained as a result of dry numbers! " - says Igor Bobrov.

So, the objective method. We take a 4-ohm 13-centimeter car speaker from the category of cheap ones and measure it. We find out the Till-Small parameters using the AudioTester program, which is widespread among those who like to dig deeper into acoustics. The resonant frequency of the speaker was found to be 96 Hz. And, alas, neither she nor other parameters changed after impregnation ... Perhaps the suspension material of our cheap speaker turned out to be one of those that are not affected by the "tire restorer"?

The subjective method was also tested. We have processed the speaker of the Philips home music center made in the mid-90s, which sounded pretty good in the past, and today is "retired". It would be difficult not to notice the result: we missed the suspension of one speaker from the pair, and listened to the result, quickly switching the sound from processed to unprocessed, and back. Alas, no changes were noted ...

Expert Opinion on Impregnating Speaker Surrounds with Tire Repair Fluid

We asked an expert in car and home audio to comment on the miracle cure and "5 Minutes Sound Tuning". Our consultant, using his rich experience, expressed himself quite extensively:

- Let's start from afar. It often happens that a speaker is potentially good, but the case does not allow it to give out the maximum of its sound quality. For example, most household shelves acoustic systems, even from brands with a solid reputation, the bass reflex is tuned too low, which improves the depth of the bass, but radically degrades its clarity and concentration. Pure Marketing: Deeper bass will be heard by everyone, and not everyone will appreciate the accuracy and clarity with a shallower bass depth.

If the speaker acoustics are not optimal, they can be improved by changing the cabinet characteristics. But, oddly enough, it is permissible to approach the same task from the other side: to change the parameters not of the case, but of the speaker itself. For example, by acting on the centering washer (which has the greatest influence on the vibration characteristics of the moving system of the speaker) or the same suspension (which affects, but to a much lesser extent than the washer).

However, the impregnation of suspensions, about which in question above, is carried out solely for the purpose of softening them and is recommended to everyone, regardless of the type of speakers and their design, which is unacceptable. For it is completely wrong to believe that in any dynamics one should strive for the maximum increase in the elasticity of the washer and suspension!

It often happens that the exact opposite is needed. Here's another example. Dynaudio car woofers / midrange speakers are good for everyone, except for one thing - they have a sluggish midbass in the volume of the car door, which is most often at least 28-30 liters. The lethargy of the midbass is a reaction to a suboptimal, excessive volume. But experienced car audio enthusiasts know that it is easy to get rid of this problem if you install a speaker in a 15-17 liter cabinet. It is possible to make a body of a given volume inside the door, but none of the installers likes this. It is much easier to saturate the speaker centering washer in order to increase its rigidity, and if done correctly, then the speaker will have the necessary speed and clarity when working on the volume of the door.

returning to a specific example using the "magic liquid", which the suspensions are impregnated with in order to increase their elasticity, it should be noted that softening the suspension entails an increase in the equivalent volume Vas and a decrease in the resonant frequency Fs. That is, of the three main parameters of any speaker, we change (moreover, uncontrollably) two, and what will happen to the third (full Qts), and no one knows at all.

Yes, it is possible that in this way it will be possible to hit the sky with a finger and randomly improve the sound of an initially non-optimal system. If the suspension is initially generally oak, then the speaker and the sensitivity will become higher, which is why it will sing louder. Effective damping is also required from the suspension, that is, the damping of resonances, and if, again accidentally, the damping qualities of the suspension are improved as a result of impregnation, then the sound will become clearer.

But how will the treated suspension behave in severe frost or heat? Will not a too soft gimbal begin to slam at an average volume and what will happen to it when working at a high volume? The risk of getting a deterioration in the final result when influencing the parameters blindly is extremely high.

I recommend vintage Golden Era hi-fi speakers for systems, but I always warn you that best models loudspeakers, as a rule, need serious restoration work. Ten years ago, you could still hear good sounding from vintage speakers in the "as is" state, but the processes of degradation of certain technical nodes- mainly suspensions - are growing like an avalanche, and today it is almost impossible to find Diatone or Technics speakers that could sound good without restoration intervention. (note: Technics speakers have rubber suspensions - in the title of the article there is a mention of fabric ones, since at the time of the new edition of the article the link is indexed)

In addition, the persistent demand for vintage acoustics every day reduces the number of preserved copies on the market, and those wishing to purchase top-end and pre-top speaker models increasingly have to be content with copies in, as in the photo below.

Is it possible to restore such acoustics? Let's start with Diatone, since the photo of these speakers was posted first. Hiendmusic recommends purchasing Diatone acoustics at least 2000 series:

Diatone DS5000 and Diatone V5000 can form the backbone of the highest level system;

Diatone DS3000 - great option for small spaces in which it is supposed to walk, and not just sit and listen to music;

Diatone DS2000 - great speakers for a relatively inexpensive setup.

All "Diatons" are distinguished by a juicy drive sound, which sometimes can seem too bright and harsh, which is more likely due to the combination of digital sources with transistor amplification than a feature of the speakers created in the analog era.

Internal filters of "diatons" are reliably assembled from high-quality elements and to this day they work perfectly - there are no problems with them, and if they arise, it is not difficult to replace "tired" parts - there is no need to be afraid of it. Tweeters and mid-range domes have titanium and titanium-boron diaphragms. It is a fragile material, and broken tweeters and midrange speakers are a common result of inaccurate speaker transportation. In this case, the domes have to be changed to "donor" ones, but this is a force majeure accident, and if the domes are intact, nothing needs to be done with the speakers. Unless you carefully clean the membranes.

The only element of Diatone acoustics that requires mandatory intervention is the fabric suspensions of the bass and mid-bass speakers. They are covered on the inside special resin, which on all, without exception, the speakers dries to the state of amber. Suspensions with such resin, instead of the normal elastic-elastic state, become stiff, and the speakers do not sound right. Boomy box-shaped bass or no bass at all, harsh loud mids - the usual result of using Diatone with rigid suspensions. In the photo below, you can see the dried resin on the inside of the Diatone DS5000 midbass speaker suspension. Please note that under the influence of gravity, the resin gradually flowed from the top of the suspension to the bottom, as a result of which a thick, strong crust formed at the bottom. Because of this, the diffuser is not only deprived of the required mobility, but also works with a skew.

A common way to soften rigid suspensions is to coat them with a special liquid that dissolves the resin. This liquid is sold in Japan, and you can easily find it on the net.The problem is that softening the suspensions in this way helps to short term- about six months. Then the process must be repeated, and after 3-4 cycles, the resin on the suspension finally degrades, depriving the speaker of the correct sound forever, or rather, until deep restoration intervention.

Another problem with the Japanese liquid is the silly YouTube videos of Diatone owners showing how soft their suspension is. Because of these rollers, many believe that the suspensions need to be softened to the limit, turn them into snot, and again, deprive the speakers of the ability to sound correctly until they are completely restored.

When I offer Diatone acoustics, I immediately carry out a complete restoration of suspensions according to a recipe that I developed by trial and error over three months. The photo shows some of the experimental mixtures that were rejected as a result of dozens of experiments.

In the end, I managed to find the right recipe and now, after my processing, the Diaton speakers sound perfect, and the result remains for many years. You can get acquainted with the process by watching a short VIDEO. I must warn you right away that I am not disclosing the secret of processing.

In addition to restoring suspensions, Diatone acoustics often need cosmetic repair enclosures and painting of gold-plated rims of the speakers - they are almost always covered with ugly corrosion.

As a result of the restoration, the acoustics acquire a collectible look and sound great. The photo below shows the very couple whose photos were at the beginning of the article. Now she plays great on the system of one of my clients.

Another model of acoustics, which is mandatory requires restoration, and more serious than Diatone - this is Technics SB8000. This is an excellent phase-linear acoustics with paper cones, capable of reproducing not too heavy (up to hard rock, inclusive) music with the naturalness of a live club scene. Imagine my surprise when several customers whom I recommended to listen to these speakers at various points of sale returned disappointed. “Harsh, disgusting sound, impossible to listen to,” was the unanimous verdict.

The situation became clearer when some of these "technics" were in my workshop. The second speaker from the top of these speakers is a paper mid-high, which is responsible for frequencies of 1100-4000Hz. It should have a special foam damper on the inside. On all, without exception, the speakers of these models, such a damper dried up and crumbled from time to time, as a result of which the diffuser does not work in the mode in which it should.

In addition, paper diffusers, on which for years moisture, soot and fat settled, lost the required rigidity and became softer than necessary. The same goes for thin rubber mounts. All of these factors combine to make the Technics SB8000 a "out-of-tune grand piano", and it's no wonder that the sound of these speakers, even in the best cosmetic condition, disappoints many. It takes some serious work with the speakers to bring them back sound, and not just external freshness.

A special composition restores elasticity to flabby rubber suspensions.

Peeled and covered on both sides with two special formulations paper diffusers.

The cracked damper is replaced with a new foam rubber ring with a special impregnation.

After all the work, Technics SB8000 sounds completely different. Some people ask how can I be sure that this is exactly the sound that was forty years ago? I don’t need to be sure that it’s “that” sound - a completely natural reproduction of jazz, blues and classical recordings is enough. With an analog source, these speakers, after restoration, sound so that you feel like at a live concert in the front row of a good music club. What else is needed? You can listen to a small fragment on this VIDEO - I recommend connecting headphones.

A few more words should be said about amplification for the listed acoustics. For four out of five systems, I recommend tube-transistor biamping, but only the Diatone DS5000 has a standard connection of two amplifiers. Biumping setups with Diatone DS3000 and Technics SB8000 require additional terminals to be installed and plugged into the system, or This upgrade allows you to squeeze the maximum out of the acoustics and get a system with outstanding sound. Read more about this in the article BIAMPING CONNECTION OF THE PRE-THROUGH ACOUSTICS.