The negative impact of extraneous sounds on the human condition has long been proven. In this regard, many special rules have been developed to determine the permissible values ​​of “sound garbage”.

For example, due to background noise reaching 40 dBA, a person will begin to have problems sleeping, and with systematic noise above 60 dBA, structural changes in the body will occur in 90 cases out of 100. To minimize or completely eliminate the risk of such situations, insulating materials are used.

Types of soundproofing materials

We should start with the fact that noise is divided into separate groups:

1. Structural – caused by vibration due to the operation of various equipment (from household equipment in the house to construction equipment on the street), vehicles, elevators, etc.
2. Percussion - can be caused by stomping, moving interior items.
3. Airborne – conversations, television and radio sounds.

In building acoustics, there are three main types of sound protection from the noise discussed above:

Soundproofing

Provides protection from noise transmitted through the air (human speech, music, etc.). It works according to one of two principles: reducing the intensity of sound waves as they pass through a dense partition or sound reflection from an obstacle.

Noise insulation

This involves protection from complex sound waves caused by a combination of sounds of different strengths and frequencies. This can be structural, airborne, impact, etc. noise.

Sound absorption

Relevant for soft structures, it uses the method of converting sound energy into thermal energy.

In order to correctly select the appropriate soundproofing material, you should take into account what types of noise the protective barrier is “constructed” against.

Let's conduct a small comparative study of products from well-known manufacturers recommended for residential premises (the group under consideration included only sound insulators effective in the range of 100-3000 Hz).

Review of sound-absorbing and sound-insulating materials

Membrane sound insulators are applicable to any surface, have elasticity, small thickness and increased efficiency in noise absorption. The most popular brands in Russia are Tecsound and Zvukoizol.

Tecsound

This company is a subsidiary of the Spanish company Texsa, which appeared back in 1954. Under the Texound brand, polymer-mineral membranes are produced - elastic, thin, and available in the form of rolls.

The basis of the material is aragonite with the addition of elastomers. It is relevant in frame and frameless systems and can increase the sound insulation properties of a structure by 15 dB.

Such indicators can be compared to a thirty-centimeter concrete wall. Tecsound price – from 850 rub. per square.

Five main series of membranes are produced:

1. Tecsound Al – self-adhesive, equipped with aluminum foil.
2. Tecsound SY – synthetic self-adhesive, suitable for partitions, ceilings, facades.
3. Tecsound 35/50/70 – standard, used for sound insulation of floors and roofs.
4. Tecsound FT – synthetic foil universal, with felt coating.
5. Tecsound 100 – sheet.

Advantages include stretchability, environmental safety, temperature resistance and durability.

Soundproofing

Membrane soundproofing materials based on bitumen-polymer components, produced in Russia, appeared back in 2009. At first, only two series were produced - Zvukoizol and Zvukoizol VEM, intended for the construction sector.

The very next year, the range of products expanded significantly due to the production of several more series, which became a good alternative to foreign analogues K-Fonik ST and Tecsound. This:

1. Sound insulation VEM Standard - viscoelastic insulating material,
2. SMK – self-adhesive base,
3. Zvukoizol-M – roll bitumen-polymer membrane sound insulators with a metallized coating.

The price of domestic sound insulators is more than affordable - from 140 rubles. per square. They are characterized by many positive qualities, including versatility, good sound-absorbing properties, and water resistance.

Soundproofing panels, consisting of several layers, quickly became popular for their relative ease of installation and effectiveness. Among them, ZIPS and SoundGuard can be especially highlighted.

ZIPS

ZIPS sandwich panels, depending on the base, have different purposes. They are made from plywood (GVL) or tongue-and-groove gypsum boards combined with fiberglass or basalt slabs.

Construction based on gypsum fiber/plywood is applicable for floors, plasterboard - for ceiling and wall surfaces.

The Zips frameless system was first developed in 1999; now it includes six types of panels for different purposes:

1. ZIPS-MODULE wall for interior walls and partitions in commercial and residential premises. Index Rw – up to 14 dB.
2. ZIPS-FLOOR MODULE – prefabricated panels for reinforced concrete interfloor floors. They isolate airborne noise in the range from 7 to 9 decibels and shock noise up to 38 dB.
3. ZIPS-Vector for wall and ceiling bases, operating range up to 125 Hz, Rw index up to 11 dB.
4. ZIPS-Paul Vector - provide comprehensive sound insulation of reinforced concrete interfloor ceilings, reduce airborne noise in the range from 6 to 8 dB, impact noise - by 32.
5. ZIPS-CINEMA – additional protection with an Rw index of 16-18 dB. It is used for ceilings and walls in rooms with a high degree of outgoing sound.
6. ZIPS-III-ULTRA – additional protection of ceiling and wall surfaces from airborne noise. Operating range 100 Hz, Rw – 11 dB.

The price of ZIPS panels starts from 1,600 rubles, but this cost is fully justified by their efficiency, low degree of thermal conductivity (that is, the panels also partially serve as a heat insulator), and durability (from 10 years).

SoundGuard

Saungard panels are the “brainchild” of a German-Russian enterprise, which appeared back in 2010 on shares with the Volma company and are characterized by increased efficiency. The panel includes:

• GKL Volma for finishing cladding,
• SoundGuard profiled panel (multi-layer board made of corrugated cardboard, cardboard and mineral quartz filler),
• Frame profile.

Two years later, the SoundGuard TM was registered, after which the production of different types of soundproofing panels began:

1. SoundGuard Ecozvukoizol is a 13 mm soundproofing elastic panel consisting of seven layers with an Rw of 40 decibels.
2. SoundGuard EcoZvukoIzol Fireproof G1, with a thickness of 13 mm and a sound insulation index of up to 42 dB.
3. SoundGuard Slim, 11 mm, seven layers, reducing noise by 36 dB.
4. SoundGuard Standard, 12 mm thick, is characterized by compressive strength and an Rw index of 37 dB.
5. SoundGuardPremium, Rw equal to 44 dB, patented soundproofing material for shades, floors, partitions.

SignGard panels are certified according to all Russian standards, fireproof, easy to install, have low thermal conductivity, price from 810 rubles/sq.m. m.

Mineral wool soundproofing materials also do not lose their popularity, especially in combination with innovative developments. The brands Shumanet and Rock Wool Acoustic Butts have advanced the most in the production of sound protection based on mineral wool.

Schumanet

Shumanet mineral wool boards are produced by the same manufacturer as the ZIPS, Shumostop, Soundlux, Soundline, Vibrosil, Vibroflex panels, namely Acoustic Group LLC.

The Shumanet series of soundproofing materials is designed directly for frame wall and ceiling systems using various types of cladding - gypsum fiber, plasterboard, particle board, plywood. The series includes:

1. Shumanet-SK are fiberglass plates, covered on one side with fiberglass, which prevents the glass fibers from falling off. Relevant when installing acoustic panels such as Knauf-Soundline, Soundboard, etc., they have a sound absorption value of about 0.8 units.
2. Shumanet-Eco - water-repellent boards based on staple fiberglass and acrylic binder. Sound absorption coefficient – ​​0.85 units.
3. Shumanet-BM - basalt slabs with a high sound absorption rate - 0.95 units.

To isolate impact noise in floor structures, a system of combined slabs called Shumostop and bitumen-polymer gaskets Schumanet-100 is produced.

The average price of Schumanet slabs is from 190 rubles per square. They are distinguished by their durability (working life from 10 years), ease of installation, meet the requirements of GOST, and are certified according to the standards of the Russian Federation.

RockWool Acoustic Butts

Multifunctional basalt slabs are produced at almost 30 factories; this is the development of a transnational group of companies that opened its first branch in Russia back in 1999.

Rockwool Acoustic Butts stone wool slabs are practically universal, applicable in interior, exterior and roof cladding in residential and industrial construction.

There are several main series of Acoustic mineral wool slabs:

1. RockWool Floor Butts are rigid, vapor-permeable boards for floor structures with expectedly high loads.
2. RockWool Floor Butts are water-repellent (hydrophobic) for public, commercial and residential premises.
3. RockWool Floor Butts I - gabbro-basalt slab materials for industrial premises.
4. Rockwool Acoustic Butts Pro - ultra-thin slabs.
5. Acoustic Butts standard type.

Rockwool Acoustic Butts products have a lot of advantages, and the price of the slabs is quite affordable - from 120 rubles per square meter.

This is a new series of posts dedicated to acoustic systems. Due to the fact that the topic is extremely broad, we decided to create a series of articles reflecting the selection criteria when purchasing speakers. This post is dedicated to the acoustic properties of cabinet materials and acoustic design. The post will be especially useful for those who are faced with choosing speakers, and will also provide information for people who want to create their own speakers in the process of their DIY experiments.

There is an opinion that one of the decisive factors affecting the sound of speakers is the material of the housing. PULT experts believe that the importance of this factor is often exaggerated, however, it is truly important and cannot be written off. An equally important factor (among many others) that determines the sound of speakers is the acoustic design.

Material: from plastic to granite and glass

Plastic - cheap, cheerful, but resonates

Plastic is often used in the production of budget speakers. The plastic body is lightweight, significantly expands the possibilities of designers; thanks to casting, almost any shape can be realized. Different types of plastics differ greatly in their acoustic properties. In the production of high-quality home acoustics, plastic is not very popular, but it is in demand for professional samples, where low weight and mobility of the device are important.

(for most plastics the sound absorption coefficient ranges from 0.02 - 0.03 at 125 Hz to 0.05 - 0.06 at 4 kHz)

Tree - from felling to golden ears

Due to its good absorption properties, wood is considered one of the best materials for making speakers.

(the sound absorption coefficient of wood, depending on the species, ranges from 0.15 – 0.17 at 125 Hz to 0.09 at 4 kHz)

Solid wood and veneer are used relatively rarely for the production of speakers and, as a rule, are in demand in the HI-End segment. Wooden speakers are gradually disappearing from the market due to low manufacturability, instability of the material and prohibitively high cost.

It is interesting that in order to create truly high-quality speakers of this type that meet the requirements of the most sophisticated listeners, technologists must select material at the cutting stage, as in the production of acoustic musical instruments. The latter is related to the properties of wood, where everything is important, from the area where the tree grew, to the humidity level of the room where it was stored, the temperature and duration of drying et cetera. The latter circumstance complicates DIY development; in the absence of special knowledge, an amateur creating a wooden speaker is doomed to act by trial and error.

Manufacturers of such acoustics do not report how the situation really is and whether the described conditions are met, and accordingly, any wooden system requires careful listening before purchasing. With a high degree of probability, two speakers of the same model from the same breed will sound slightly different, which is especially important for some discerning listeners with golden ears with big money.

Columns from an array of valuable rocks are available in units, their cost is astronomical. Everything yours truly has heard sounds excellent. However, in my subjectively pragmatic opinion, it is disproportionate to the cost. Sometimes, well-designed enclosures made of plywood and MDF have no less musicality, but for many audiophiles “not wood” = “not true hi-end”, and for some, “not wood” simply does not allow the status or spoils the interior design.

I believe that one of the best wooden systems in our catalog is this:
Floor-standing acoustics Sonus Faber Stradivari Homage graphite (price appropriate)

Plywood is almost a tree if it hasn't flown over Beijing

Plywood, used for the production of acoustic enclosures, has from 10 to 14 layers and is almost as good as wood in terms of acoustic properties, in particular in sound absorption, while being somewhat cheaper than wood, more technologically advanced in processing, lighter than chipboard and MDF. Multilayer plywood dampens unwanted vibrations well due to the structure of the material.

(sound absorption coefficient of 12-layer plywood ranges from 0.1–0.2 at 125 Hz to 0.07 at 4 kHz)

Like wood, plywood is used in quite expensive and sometimes luxury piece products. The cost of plywood speakers is not much lower than those made from solid wood, and are quite comparable in quality.

In some cases, cases declared by the manufacturer as “plywood” are made of chipboard and MDF. Therefore, low prices for speakers with plywood or wooden casings should alert you. A number of small Asian manufacturers, which change names regularly and sell mostly online, create composite cabinets that include a few small but noticeable plywood (wood) elements, with the bulk made from chipboard.

Among the speakers made from plywood, I can especially highlight this one: Yamaha NS-5000 bookshelf speakers

Chipboard – thickness, density, humidity

Chipboard is comparable in cost to plastic, but does not have a number of disadvantages that are inherent in plastic cases. The most significant problem of chipboard is low strength, with a fairly high mass of material.

Sound absorption in chipboard is non-uniform and in some cases low- and mid-frequency resonances may occur, although the likelihood of their occurrence is lower than in plastic. Plates with a thickness of more than 16 mm, which achieve the required density, can effectively dampen resonances. It should be noted that, as in the case of plastic, the properties of a particular chipboard are of great importance. It is important to take into account the density and humidity of the material, since different chipboards differ in these parameters. Thick, dense chipboards are often used to create studio monitors, which indicates the demand for the material in the production of professional equipment.

On a note, for comrades from the DIY fraternity, chipboard with a density of at least 650 - 820 kg/m³ (with a board thickness of 16 - 18 mm) and a humidity of no more than 6-7% is well suited for creating speakers. Failure to comply with these conditions will significantly affect the sound quality and reliability of the speakers.

Among worthy chipboard options for home speakers, our experts highlight: Cerwin-Vega SL-5M

MDF: from furniture to acoustics

Today, MDF (Medium Density Fiberboard) is used everywhere, among other things, MDF is one of the most common modern materials for the production of acoustics.

The reason for the popularity of MDF was the physical properties of the material, namely:

• Density 700 - 800 kg/m³
• Sound absorption coefficient 0.15 at 125 Hz – 0.09 at 4 kHz
• Humidity 1-3%
• Mechanical strength and wear resistance

The material is cheap to produce, has acoustic properties comparable to those of wood, while the resistance of the boards to mechanical damage is somewhat higher. MDF has sufficient acoustic rigidity of the speaker cabinet, and sound absorption meets the parameters necessary for creating HI-FI acoustics.
Visual difference between MDF and chipboard

There are a lot of wonderful systems among MDF acoustics; in my opinion, the optimal ones in terms of price/quality ratio are the following:

→ Yamaha NS-BP182 piano black - bookshelf

→ Focal Chorus 726 - floor-standing

Aluminum alloys - design and precise calculations

The most common metal in the production of speakers is aluminum, as well as alloys based on it. Some authors and experts believe that the aluminum housing reduces resonances and also improves the transmission of high frequencies. The sound absorption coefficient of aluminum alloys is not high, and is about 0.05, which, however, is significantly better than that of steel. To reduce body vibration, increase sound absorption and prevent harmful resonances, manufacturers use sandwich panels, where a layer of high molecular weight polyethylene resins or other low-density materials, such as viscoelastic, is placed between 2 aluminum sheets.

In the case of budget aluminum speakers, manufacturers often rely on design at the expense of sound: as a result, the acoustic characteristics leave much to be desired. Sometimes users of such acoustics complain of a harsh, distorted sound caused by insufficient sound absorption of the housing. Due to the fact that waves are well reflected and poorly absorbed, precise calculation of the housing design, selection of emitters, filters used, as well as the quality of connections of individual parts become very important in metal acoustics.

Among decent-sounding aluminum speakers, I was especially impressed by the sound:

→ Canton CD 310 white high gloss (impressive price, but not prohibitive)

Stone – granite slabs at the price of gold bars

Stone is one of the most expensive materials for the production of acoustic enclosures. Impeccable reflection and the practical impossibility of the appearance of vibrational resonances make these materials in demand among particularly demanding listeners.

Most rocks have a stable sound absorption coefficient, which, for example, for granite is 0.130 for the entire spectrum of sound frequencies, and for limestone 0.264. Manufacturers especially value porous stones, which have higher sound absorption.

Using stone slabs to make DIY acoustics is almost impossible, since it requires not only remarkable knowledge in acoustics and stone processing, but also extremely expensive equipment (no one produces home-made 3-D stone milling machines yet).

For the production of serial speakers, rocks such as granite, marble, slate, limestone, and basalt are used. These rocks have similar acoustic properties, and with appropriate processing they become real works of art. Stone enclosures are often used to create landscape acoustics; in such cases, a cavity is created in the raw stone to accommodate the emitter, in which fastening elements are installed (usually made to order).

The stone has 2 main problems: cost and weight. The price of a stone speaker may be higher than any other with similar characteristics. The weight of some samples of floor systems can reach 40 kg or more.

Glass transparency and sound quality

An original solution is to create speakers from glass. So far, only two companies, Waterfall and SONY, have seriously succeeded in this matter. The material is interesting from a design point of view; acoustically glass creates certain problems, mainly in the form of resonances, which the above-mentioned companies have learned to solve; there are even reference options.

The prices for the transparent miracle can also hardly be called affordable; the latter is associated with low manufacturability and high production costs.

Of the glass samples that impressed with their sound, I can recommend: Waterfall Victoria Evo

Acoustic design - boxes, tubes and horns

Acoustic design is no less important for accurate sound transmission in speakers. I will talk about the most common types (it is natural that certain types can be combined depending on the specific model, for example, the bass-reflex part of the speaker is responsible for the low and mid-frequency range, and a horn is built for high frequencies).

Bass reflex - the main thing is the length of the pipe

A bass reflex is one of the most common types of acoustic design. This method allows, with the correct calculation of the length of the pipe, the cross-section of the hole and the volume of the housing, to obtain high efficiency, an optimal frequency ratio, and amplify low frequencies. The essence of the phase inverter principle is that on the back of the body there is a hole with a pipe, which allows you to create low-frequency oscillations in phase with the waves created by the front side of the diffuser. Most often, the bass reflex type is used when creating 2.0 and 4.0 systems.

To make calculations easier when creating your own speaker, it is convenient to use special calculators; one of the convenient ones is provided at the link.

In the HI-END philosophy, there are extremely radical, uncompromising judgments about bass reflex systems; I present one of them without comment:

“Enemy No. 1 is, of course, nonlinear amplification elements in the sound path (then everyone, to the best of their education, understands which elements are more linear and which are less). Enemy No. 2 is the bass reflex. the bass reflex is designed to show off, it should allow a small cheap speaker to record 50... 40... 30 in the passport, and what a trifle even 20 Hz at a level of -3 dB! But the lower frequency range of the bass reflex ceases to be relevant to music; more precisely, the bass reflex itself is a pipe singing its own melody.”

A closed box is a coffin for extra low ones

The classic option for many manufacturers is a regular closed box with speaker diffusers brought to the surface. This type of acoustics is quite simple to calculate, but the efficiency of such devices is not great. Also, the boxes are not recommended for lovers of characteristically pronounced lows, since in a closed system without additional elements that can enhance the lows (bass reflex, resonator), the frequency spectrum from 20 to 350 Hz is poorly expressed.

Many music lovers prefer the closed type, since it is characterized by a relatively flat frequency response and realistic “honest” transmission of the reproduced musical material. Most studio monitors are created in this acoustic design.

Band-Pass (closed resonator box) – the main thing is not to buzz

Open body - no extra walls

A relatively rare type of acoustic design today, in which the rear wall of the housing is repeatedly perforated or completely absent. This type of design is used to reduce the number of housing elements that affect the frequency response of the speakers.

In an open box, the front wall has the most significant influence on the sound, which reduces the likelihood of distortion introduced by other parts of the case. The contribution of the side walls (if any are present in the structure), given their small width, is minimal and amounts to no more than 1-2 dB.

Horn design - problematic loudness champions

Horn acoustic design is more often used in combination with other types (in particular for the design of high-frequency emitters), however, there are also original 100% horn designs.

The main advantage of horn speakers is their high volume when combined with sensitive speakers.

Most experts, not without reason, are skeptical about horn acoustics, for several reasons:

• Structural and technological complexity, and accordingly, high requirements for assembly
• It is almost impossible to create a horn speaker with a uniform frequency response (with the exception of devices costing 10 kilobucks and more)
• Due to the fact that the horn is not a resonating system, it is impossible to correct the frequency response (a minus for DIYers who intend to copy a Hi-end horn)
• Due to the peculiarities of the waveform of horn acoustics, the sound volume is quite low
• Overwhelmingly relatively low dynamic range
• It produces a large number of characteristic overtones (considered a virtue by some audiophiles).

Horn systems have become the most popular among audiophiles in search of “divine” sound. The tendentious approach allowed the archaic horn design to get a second life, and modern manufacturers were able to find original solutions (effective, but extremely expensive) to common horn problems.

That's all for now. To be continued, as usual, but the “autopsy” will definitely show... I’ll announce for the future: emitters, power/sensitivity/room volume.

habr.com

The best soundproofing material, soundproofing ratings

Soundproofing of residential premises is becoming more and more relevant every year. And every homeowner wants to choose the best soundproofing material to protect against outside noise. Although it is difficult to choose soundproofing products based on the “good or bad” principle, since many of them have a specific purpose and, to one degree or another, fulfill the intended purpose.

The best soundproofing material, top six ranking

As a rule, sound insulation is a complex multilayer structure, including dense layers that reflect sound waves and soft layers that absorb extraneous sounds. In this regard, neither mineral wool, nor membrane, nor panel materials should be used as independent sound insulation.

At the same time, it is a mistake to assume that heat insulators (cork, PPS, PPE, etc.) are capable of fully fulfilling the role of noise protection. They are not able to stop creating a barrier against the penetration of structural noise. Even worse, if sheets of polyurethane or polystyrene foam are glued to the wall under the plaster, then such a design will increase the resonance of incoming noise.

Review of the best soundproofing materials

Rock Wool Acoustic Butts

In first place we can put Rockwool Acoustic Butts, a group of companies that have been producing basalt fiber slabs for the eighth decade. Stone wool, pressed into panels, has found its use in both residential and industrial construction as a heat and sound insulator.

Advantages of Rockwool Acoustic Butts:

• High sound absorption class (A/B depending on thickness), excellent sound absorption ability: air vibrations up to 60 dB, shock – from 38.
• Low thermal conductivity and complete fire safety.
• Vapor permeability, moisture resistance, biostability, durability.
• Certification according to Russian Federation and EU standards.
• Easy to install.

Flaws:

There is a risk of purchasing a fake.

High cost, largely due to the need to use additional components and waste accounting.

Soundproofing

These are membrane-type bitumen-polymer soundproofing materials based on modified resins, which have sound, heat and waterproofing qualities. Applicable for walls, ceilings and floors, including “warm” ones using a floating system. Included in category G1 - low-flammable.

Positive properties:

• Versatility, durability, affordable price.
• Water, bio and temperature resistance (-40/+80°C).
• Low degree of thermal conductivity in accordance with SNiP 23-02-2003.
• Sound protection for airborne noise up to 28 dB, for shock – up to 23.

Negative:

• A small dealer network in the Russian Federation.
• The elements have considerable weight, and therefore they cannot be called the best option for weak load-bearing foundations.
• We only allow one installation method – adhesive.

Tecsound

The company produces polymer-mineral membrane soundproofing materials. These are flexible, elastic roll products, very dense, which is why they are classified as heavy. The basis is aragonite and elastomers. Belongs to classes G1 and D2 - low flammability, with an average degree of smoke formation.

Advantages:

• Resistance to rotting, moisture and temperature resistance (properties do not change even at t°-20), durability.
• Versatility due to the property of stretching.
• Certification according to Russian and European standards.
• Environmental safety due to the absence of phenol-containing substances.
• Reduction of airborne noise up to 28 dB.

Flaws:

• Possibility of installation - only adhesive.
• Not applicable as an independent material for sound insulation.

The cost is above average.

Schumanet

Mineral wool boards of the Schumanet series are designed for wall and ceiling frame soundproofing systems for subsequent finishing with facing materials (plywood, plasterboard or fiber sheets, chipboard).

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• Resistance to humidity, formation of mold and mildew, durability.
• Excellent vapor permeability and minimal thermal conductivity.
• Complete fire safety and non-flammability - classes KM0 and NG.
• Compliance with high sound absorption classes - A/B at any frequency, reduction of structural and airborne noise waves from 35 dB.
• Russian Federation certification.
• Easy to install due to its elastic properties.

Flaws:

An increased degree of phenol emission (slightly exceeds the permissible level), that is, environmental friendliness is in question.

High cost due to the need to purchase many additional items. elements, the need to strictly follow the installation instructions.

ZIPS panels

The panel system from the manufacturer Acoustic Group appeared at the very end of the last century. This is a multi-layer structure, the composition of which varies depending on its purpose. For ceiling and wall surfaces, tongue-and-groove plasterboard sheets are used as a base, and for floor surfaces, gypsum fiber sheets are used. They are supplemented with fiberglass or basalt slabs. To a large extent, vibration units made of polymer and silicone prevent the transmission of vibration and noise waves. Flammability degree G1 (low flammability).

Advantages:

• Durability, efficiency and biostability.
• Low thermal conductivity.
• The absence of inter-plate gaps during installation is ensured by the tongue-and-groove type of connection.
• There is no need to use adapters when attaching plates.
• Compliance with GOST requirements.

Flaws:

When mounted on a wall, the slabs can resonate by 2-3 dB with incoming and outgoing low-frequency noise up to 100 Hz.

During the installation process, many components are required, which significantly increases the final cost of installation.

SoundGuard Plates

A fairly effective product, attractive at an affordable price, produced by an alliance of experienced manufacturers who have been known on the Russian market for many years. Prefabricated noise protection structure includes:

• Drywall Volma,
• SoundGuard profiled board (consists of plasterboard with mineral-quartz filler and a cardboard cellulose panel),
• Frame profile.

According to the degree of flammability, they belong to group G2 (moderately flammable), toxicity T1 (low). The advantages of SaunGuard panels include:

Compliance with all safety requirements and certification of the Russian Federation.

Versatility - the slabs are suitable for any wall and floor bases.

Minimum thermal conductivity.

Good sound insulation performance (airborne noise - up to 60 dB, shock - up to 36).

Easy installation, the ability to choose the installation method (adhesive, frame, using plastic dowels).

Disadvantages:

• Lack of moisture resistance properties.
• There are few sales representatives in Russia.
• High prices.
• During the cutting process, the mineral filler is shed. This necessitates the need to cover the edges of all slabs with tape or tape.

In addition, if the panels are used as an independent sound insulator, then the degree of interference with impact and airborne noise does not exceed 7 dB. Like ZIPS, panels can resonate with low-frequency noise.

otdelkadom-surgut.ru

Soundproofing of premises for various purposes – Acoustic Group

Acoustic Group has been bringing peace and quiet to its clients' homes for over 18 years. We produce and sell materials designed to create a comfortable acoustic environment. Our specialization is sound insulation in apartments, offices, and factories, a wide range of vibration insulation tasks, and acoustics of premises for various purposes, including theaters, concert and sports halls, as well as cinema halls. Our acoustic engineers are ready to solve almost any problem:

• Acoustic design;
• Measurements;
• Expertise;
• Consulting;
• Project support.

Our customers are not only corporate clients, but also individuals. Most often they require soundproofing for an apartment. At the same time, we approach each case individually, understanding that universal recipes do not always work. Our task is to achieve the desired result, and not to sell a solution that is convenient for ourselves. Our portfolio includes many different projects, from small apartments and country houses to world-famous concert and theater halls.

Acoustic Group - professional soundproofing and soundproofing of apartments, offices, premises for various purposes with guaranteed results

A lot depends on acoustic parameters: the sound quality of audio equipment, the penetration of street noise or noise from neighbors and, ultimately, the comfort of staying in the room. To create a calm and comfortable atmosphere, our engineers have developed and introduced unique materials into production. Soundproofing solutions from Acoustic Group for floors, walls and ceilings have been time-tested and, nevertheless, are constantly being improved and updated. All Acoustic Group products are certified and meet the most stringent quality standards.

We offer sound insulation solutions for walls and ceilings:

Frameless systems. Modern sound insulation using ZIPS sandwich panels. Effective, high quality, the thinnest of those that actually work. At the same time, it is quickly and easily installed. They provide ADDITIONAL sound insulation for airborne noise at a level of 9-18 dB (depending on the chosen design).

Frame systems. Thicker. However, they are also effective. They are made using the Gyproc Ultrastil metal profile, Vibroflex vibration suspensions, special weighted plasterboard Aku-Line, acoustic plates Shumanet-ECO, SK or BM. Provide reliable protection of premises from external noise.

Sound insulation of the room: floor materials

• Shumanet-100Combi and 100Hydro - under the screed, to comply with impact noise standards (can be used in several layers to enhance the effect).
• Noise stop C2 and K2 - under the screed, for maximum sound insulation in terms of impact and airborne noise.
• Shumoplast - under the screed, for uneven floors.
• Akuflex underlay for finishing coatings to protect neighbors from impact noise.
• Vibrostek-M, Sylomer SR, Shumanet-EKO, SK or BM, Vibrosil - for floor structures on joists.

Soundproofing of premises: materials for walls and ceilings

• ZIPS-III-Ultra, ZIPS Vector, ZIPS Module, ZIPS Cinema - sandwich panels for frameless sound insulation.
• Acoustic triplex Soundline-dB
• Soundproofing panels Soundline-PGP Super for thin partitions
• Special weighted gypsum board Aku-Line
• Vibroflex suspensions and wall mounts
• Acoustic slabs Schumanet EKO, BM, SK

Vibration isolation: materials

• Sylomer SR is a polyurethane elastomer with a wide range of applications.
• Isotop - spring vibration isolators.
• Vibroflex suspensions 1/30 M8 and 4/30 M8.
• Vibroflex SM vibration isolation supports.
• Mastic Vibronet.

Proper acoustics in a room can be achieved by creating decorative and acoustic materials that not only provide aesthetic appeal, but also allow you to adjust the acoustic characteristics.

Advantages of Acoustic Group:

• Impeccable quality. Only proven effectiveness, many years of implementation experience and positive customer reviews.
• Reasonable cost of materials. Sound insulation for an apartment is a rather expensive item in the renovation estimate. However, our price for materials, upon detailed calculation, turns out to be not only justified, but also one of the best on the market.
• Full range of services. We don't just supply materials. Our engineers are ready for comprehensive work on site from the design stage to the moment of commissioning of the facility, carrying out all the necessary acoustic measurements.
• Wide geography. Our products are available throughout Russia, as well as in the CIS countries. You can buy it directly at Acoustic Group sales offices or from the company’s partners. You can directly order soundproofing of your apartment from us in Moscow, Kyiv, Minsk, Almaty and many other cities.

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Acoustic design - Basics of acoustics

The well-known confusion in understanding the principles of formation of the bass section of acoustics is largely due to the information policy of advertising, and often reference publications. There, the potential buyer is first told the size of the speaker, then its power, then the mythical “frequency range” and ends with the winning price.

All? Not so! This is where it all begins. In English, the speaker itself is called driver - drive, and this is very correct. Just as an engine will become a car only by enriching itself with everything that humanity has developed for this, so a speaker will become a loudspeaker only in its inherent acoustic design.

With high-frequency and mid-frequency heads the situation is relatively simple: the high-frequency heads carry their own acoustic design, while the mid-range heads require minimal dimensions.

Bass players are a different matter. Here, almost everything is determined by the choice of acoustic design, and depending on this choice, all the parameters communicated to you will be subject to revision: power, frequency range, and, in a certain sense, price. Because with skillful selection of parameters, you can achieve the sickening sound of the most expensive and thoroughbred bass speaker.

Now it’s time to “announce the entire list.” It's not that long:

The task of any low-frequency acoustic design is solved according to the ancient principle of “divide and conquer”. “Separate” means that the vibrations emitted by one side of the diffuser must be somehow separated from the vibrations created by its opposite side, simultaneously and in antiphase with the first. “Conquer” means that the “extra” sound waves cut off in this way can be dealt with in different ways.

Historically, the first acoustic design was an acoustic screen. It holds the defense, preventing oscillations from one side of the diffuser to the other and preventing them from being mutually destroyed up to frequencies at which the shortest distance between the front and back sides of the diffuser becomes comparable to the half-wavelength of the emitted frequency. And below this frequency, the acoustic screen “becomes completely incapable” and allows antiphase waves to cancel each other out as they please. To suppress an acoustic short circuit at a frequency of, say, 50 Hz, the shield must have a size of 3 meters by 3. Therefore, this type of acoustic design has long lost its practical significance, although it is still used as a reference when measuring speaker parameters.

Structurally, the simplest acoustic design of those practically used is closed box (sealed or closed in foreign terminology). Here, unnecessary vibrations are dealt with decisively and abruptly: locked in a confined space behind the diffuser, they will sooner or later fade away and turn into heat. The amount of this heat is tiny, but in the world of acoustics everything is in the nature of small disturbances, so how this thermodynamic exchange occurs is not indifferent to the characteristics of the acoustic system. If the sound waves inside the loudspeaker body are allowed to dangle unattended, a significant part of the energy will be dissipated in the volume of air contained inside the case, it will heat up, albeit slightly, and the elasticity of the air volume will change, and in the direction of increasing rigidity. To prevent this from happening, the internal volume is filled with sound-absorbing material. While absorbing sound, this material (usually wool, natural, synthetic, glass or mineral) also absorbs heat. Due to the significantly greater heat capacity of sound-absorbing fibers than air, the temperature increase becomes much smaller and it “seems” to the speaker that there is a significantly larger volume behind it than in reality. In practice, in this way it is possible to achieve an increase in the “acoustic” volume compared to the geometric one by 15 - 20%. This, and not at all the absorption of standing waves, as many believe, is the main point of introducing sound-absorbing material into closed loudspeakers.

A variation of this (and not the previous one, as is often believed) type of acoustic design is the so-called “ endless screen" In English-language sources, this type of design is called infinite baffle or free-air. All the names given are equally misleading. We are all adults here and we understand that in practice there cannot be an endless screen. In fact, an infinite screen is considered to be a closed box with a volume so large that the elasticity of the air enclosed inside it is much less than the elasticity of the diffuser suspension, so that the speaker simply does not notice this elasticity and the characteristics of the speaker system are determined only by the parameters of the head. Where the boundary lies, starting from which the volume of the box becomes seemingly infinite, depends on the parameters of the speaker. However, when solving practical problems, this volume always turns out to be the internal volume of the trunk, which, even in a small car, will give the reaction of an “infinitely large” volume even for a large speaker. Another thing is that not every speaker will work well in such a design, but we will discuss this separately when we talk about choosing a speaker for an acoustic design (or vice versa).

Despite all the (by the way, apparent) simplicity of a closed box as an acoustic design for the low-frequency section of car acoustics, this solution has many advantages that are absent in other, more sophisticated designs.

Firstly, the simplicity (or simplicity) of calculating characteristics. A closed box has only one parameter - internal volume. You can choose the right one if you try! The margin for errors here is reduced to a minimum.

Secondly, over the entire frequency range, down to zero, the vibrations of the diffuser are restrained by the elastic reaction of the air volume inside the box. This significantly reduces the likelihood of speaker overload and mechanical damage. I don’t know how comforting this sounds, but for avid bass lovers, the speakers in closed boxes sometimes burn, but almost never “spit out”.

Thirdly, only a closed box is a second-order acoustic filter, that is, it has a drop in frequency response below the resonance frequency of the head-box system with a slope of 12 dB/oct. Namely, the frequency response of the interior volume of a car, below a certain frequency, has precisely this steepness, only in the opposite sign. If you guess, calculate or measure (whatever happens), it becomes possible to obtain a perfectly horizontal frequency response at lower frequencies.

Fourthly, with the right choice of head parameters and volume for it, a closed box has no equal in the field of impulse characteristics, which largely determine the subjective perception of bass notes.

The natural question now is - what’s the catch? If everything is so good, why are all other types of acoustic design needed?

There is only one catch. Efficiency For a closed box it is the smallest compared to any other type of acoustic design. Moreover, the smaller we manage to make the volume of the box, while maintaining the same operating frequency range, the less effective it will be. There is no more insatiable creature in terms of power input than a closed box of small volume, which is why the speakers in them, as was said, although they do not spit out, they often burn...

The next most common type of acoustic design is bass reflex(ported, vented, bass-reflex), more humane in relation to the radiation from the rear side of the diffuser. In a bass reflex, part of the energy that is “put against the wall” in a closed box is used for peaceful purposes. To do this, the internal volume of the box communicates with the surrounding space through a tunnel containing a certain mass of air. The size of this mass is chosen in such a way that, in combination with the elasticity of the air inside the box, it creates a second oscillatory system that receives energy from the back side of the diffuser and radiates it where needed and in phase with the radiation of the diffuser. This effect is achieved in a not very wide frequency range, from one to two octaves, but the efficiency is within its limits. increases significantly, according to the principle “no waste - there are unused resources.” In addition to higher efficiency The bass reflex has another important advantage - near the tuning frequency, the amplitude of the diffuser oscillations significantly decreases. This may at first glance seem like a paradox - how the presence of a hefty hole in the loudspeaker cabinet can restrain the movement of the cone, but nevertheless it is a fact of life. In its operating range, the bass reflex creates completely greenhouse conditions for the speaker, and exactly at the tuning frequency the oscillation amplitude is minimal, and most of the sound is emitted by the tunnel. The permissible input power is maximum here, and the distortion introduced by the speaker is, on the contrary, minimal. Above the tuning frequency, the tunnel becomes less and less “transparent” to sound vibrations, due to the inertia of the air mass contained inside it, and the loudspeaker acts as if it were closed. Below the tuning frequency, the opposite happens: the inertia of the speaker gradually disappears and at the lowest frequencies the speaker operates practically without load, that is, as if it had been removed from the housing. The amplitude of oscillations quickly increases, and with it the risk of spitting out the diffuser or damaging the voice coil from hitting the magnetic system. In general, if you do not take precautions, going for a new speaker becomes a real prospect.

A means of protecting against such troubles, in addition to being careful in choosing the volume level, is the use of infra-low-pass filters. By cutting off the part of the spectrum where there is still no useful signal (below 25 - 30 Hz), such filters prevent the diffuser from going into disarray at the risk of your own life and your wallet.

Bass reflex significantly more capricious in the selection of parameters and settings, since three parameters are subject to selection for a specific speaker: box volume, cross-section and tunnel length. The tunnel is very often made so that with a ready-made subwoofer it is possible to adjust the length of the tunnel by changing the tuning frequency.

Due to the presence of two interconnected oscillatory systems, the bass reflex is a fourth-order acoustic filter, that is, its frequency response theoretically has a roll-off of 24 dB/oct below the tuning frequency. (Actually, from 18 to 24). It is almost impossible to obtain a horizontal frequency response when installed in a cabin. Depending on the ratio of the size of the cabin (and, therefore, the characteristic frequency from which the rise in the frequency response of the internal acoustics begins) and the tuning frequency of the bass reflex, the total characteristic may have deviations from a delicate hump to crazy Amur waves. The hump, that is, a smooth rise in the frequency response at lower frequencies, is often just what is needed for optimal subjective perception of bass in a noisy space, but sudden changes in amplitude with an unsuccessful choice of parameters have earned the bass reflex, completely undeservedly, the nickname boom-box (“booze”) . To restore justice, we note that the thumping effect can be achieved from a closed box - I’ll explain how next time; and a properly designed bass reflex can produce very clear and musical bass with a reasonable power input.

A type of bass reflex design is passive radiator loudspeaker(or radiator). Foreign terms: passive radiator, drone cone. Here, the creative oscillatory system, which makes it possible to utilize the energy removed from the rear side of the diffuser, is implemented not in the form of a mass of air in the tunnel, but in the form of a second diffuser, not connected to anything, but weighted to the required mass. At the tuning frequency, this diffuser oscillates with the greatest amplitude, and the main one with the smallest. As they move up in frequency, they gradually change roles. Until recently, this type of acoustic design was not used in mobile installations, although it is used quite often in home ones. The reason for the dislike was the unjustified hassle of obtaining a second diffuser (this is usually the same speaker, but without a magnetic system and voice coil) and difficulties in placing two large diffusers where a conventional bass reflex would need to place a diffuser and a small tunnel. However, recently, car subwoofers with passive radiators have appeared - need forced them. The fact is that recently a new generation of speakers with a very large diffuser stroke, designed to work in small volumes, have begun to appear. The volume of air “blown out” by them during operation is very large, and the tunnel would have to be made significant in diameter (otherwise the air speed in the tunnel will increase so much that it will hiss like a steam locomotive). And the combination of a small volume and a large tunnel diameter makes it necessary to choose a longer length for the tunnel. So it turned out that bass reflexes of a conventional design for such heads would be decorated with meter-long pipes. To avoid such unnecessary incidents, we preferred to concentrate the required oscillating mass in a passive radiator with a diffuser stroke the same as that of an active speaker.

The third type of subwoofer, quite often used in auto installations (although less frequently than the previous two) is bandpass loudspeaker. Sometimes the name “balanced-load loudspeaker” () is used. If a closed box and a bass reflex are acoustic high-pass filters, then a band-pass filter, as the name implies, combines high- and low-pass filters.

The simplest bandpass loudspeaker is single 4th order(single reflex). It consists of a closed volume, the so-called. rear chamber and a second one, equipped with a tunnel, like a conventional bass reflex (front chamber). The speaker is installed in the partition between the chambers so that both sides of the diffuser operate in completely or partially closed volumes - hence the term “symmetrical load”.

Of the traditional designs, the bandpass loudspeaker, in any version, is the champion in efficiency. Moreover, efficiency is directly related to bandwidth. The frequency response of a bandpass loudspeaker has the shape of a bell. By selecting the appropriate volumes and frequency tuning of the front chamber, it is possible to build a subwoofer with a wide bandwidth, but limited output, that is, the bell will be low and wide, or it can be with a narrow bandwidth and very high efficiency. in this strip. At the same time, the bell will stretch in height.

Bandpass- a capricious thing to calculate and the most labor-intensive to manufacture. Since the speaker is buried inside the case, it is necessary to go to some lengths to assemble the box so that the presence of a removable panel does not violate the rigidity and tightness of the structure. Coordinating the frequency characteristics of the subwoofer, interior and front speakers is also associated with a well-known headache. The impulse characteristics are also not the best, especially with a wide bandwidth. How is this compensated?

First of all, as stated - the highest efficiency.

Secondly, the fact that all sound is emitted through the tunnel, and the speaker is completely closed. When assembling such a subwoofer, considerable possibilities open up for an installer (or amateur) with imagination. It is enough to find a small place at the junction of the trunk and the passenger compartment, where the mouth of the tunnel can be placed - and the path is open to the most powerful bass. Especially for such installations, JLAudio, for example, produces flexible plastic tunnel sleeves, with which it proposes (and many agree) to connect the subwoofer output to the cabin. Like a vacuum cleaner hose, only thicker and stiffer.

Strip strips are even more effective 6th order loudspeakers with two tunnels. The chambers of such a subwoofer are adjusted at intervals of approximately an octave. A double bandpass provides less distortion in the operating band, since the speaker is loaded with bass reflexes on both sides of the diffuser, with all the advantages of such a load, but has a steeper frequency response decline below the operating band compared to a single bandpass.

An intermediate position is occupied by the so-called quasi-bandpass loudspeaker, also with a sequential setting, where the rear chamber is connected by a tunnel to the front, and the front chamber is connected by another tunnel to the surrounding space.

Three-chamber bandpass loudspeakers are simply alternative structural implementations of conventional bandpass loudspeakers, and are composed of two conventional ones, after which the wall separating them has been removed.

There are three more options for the acoustic design of low-frequency acoustics, which, although they exist, are practically not used. The first of the outsiders - acoustic labyrinth, where “energy removal” from the back of the diffuser occurs through a long pipe, usually folded for compactness, but still increasing the dimensions of the subwoofer to limits that are unacceptable in a mobile installation.

Second - exponential horn, which, in order to obtain a sufficiently low cut-off frequency, must have cyclopean dimensions, which makes its use in the low-frequency link rare, even in stationary systems where there is more space than in a car.

The third type, which has isolated precedents for use, is loudspeaker with aperiodic load in the form of concentrated acoustic resistance ( aperiodic membrane). We used to call it PAS - acoustic absorption panel. The idea is that the load for the diffuser is a nearby semi-permeable barrier, for example, dense fabric or a layer of silica wool sandwiched between perforated panels. Theoretically, such a load is inelastic in nature and, like a shock absorber in a car suspension, absorbs acoustic energy without affecting the resonant frequency of the speaker. But this is theoretical. But in practice, the presence of an air volume between the speaker and the PAS created such a mixture of characteristics and reactions that the results became difficult to predict.

So, from a quick glance at the main types of acoustic design, it is clear that there is no perfection in the world. Any choice will be a compromise. And to make the essence of the compromise clearer, let's end this correspondence meeting as it should be - by summing up the interim results. Let's compare the considered options in terms of the main factors that determine the success of their use in a mobile audio installation.

These factors should include:

Efficiency

The amount of efficiency inherent in a particular type of acoustic design ultimately determines how powerful an amplifier will be needed to achieve the required volume level, and at the same time how difficult the life of the speaker will be.

In the most important frequency range from the point of view of reproducing information in the bass register, 40 - 80 Hz, places will be distributed as follows: narrow-band bandpass loudspeakers are champions in this category, especially double-tunnel 6th order ones. They are followed by a wideband dual-tunnel and a conventional bass reflex. And finally, the ones that are most hungry for power input are a closed box and a wideband single bandpass.

Introduced distortion

In the lower octave - one and a half musical range (30 - 80 Hz) all types of acoustic design behave decently at low power levels. The bass reflex and bandpass loudspeaker are somewhat better than others, but not by much. But at high power the opponents are stretched along the distance. The best results here should be expected from a dual bandpass loudspeaker. Behind it is a single bandpass and bass reflex. And it completes the circuit - a closed box, which produces the greatest distortion at large signal amplitudes.

Impulse characteristics

Accurate reproduction of the fronts of bass instruments is perhaps the main quality for bass acoustics. Low bass efforts are of little use if they are blurred and sluggish. In this regard, a closed box promises the best results (if calculated correctly). The transient characteristics of a bass reflex can be very decent, but still on average will be inferior to a closed design. Single bandpass loudspeakers have good performance, which, however, deteriorates as the bandwidth increases. The worst response to a pulsed signal has a dual bandpass loudspeaker, again, especially a wideband one.

The work of the subwoofer should be, starting from a certain frequency, delegated to the midbass of the front speakers. For a closed box and a bass reflex, this is not a problem and the system designer has a fair amount of freedom in choosing the crossover frequency, since both this frequency and the slope of the rolloff are determined by external circuits. But narrowband bandpasses often have their own frequency rolloff starting from 70-80 Hz, where not all midbass can painlessly pick up a song. At the same time, the requirements for midbass become more complicated, and working with a crossover does not become any easier.

Let’s put all of the above in a table, based on our usual five-point system:

				Bandpass loudspeaker
				single		double
	Closed box	Bass reflex		Narrow band	Wide band	Narrow band	Wide band
Distortion at low power	4	5		5	4	5	4
Distortion at high power	2	4		4	3	5	4
Impulse characteristics	5	4		4	2	3	2
Coordination with front speakers	5	5		2	4	2	4
Overload capacity in the operating range (above 30 Hz)	>	4		5	4	5	4
Overload capacity in the infra-low frequency range below 30 Hz)	5	2		5	5	2	2
Smoothness of the frequency response taking into account the internal acoustics of the car.	5	4		2	3	2	3
Sensitivity to design and manufacturing errors	5	4		2	2	2	2

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Room acoustics - sound absorption - Paroc.ru

Products

Construction insulation

General construction thermal insulation

PAROC eXtra

PAROC eXtra light

PAROC eXtra plus

PAROC eXtra Smart

Thermal insulation of walls

PAROC InWall

PAROC WAB 10t

PAROC WAS 120

PAROC WAS 25t

PAROC WAS 35

PAROC WAS 35t

PAROC WAS 35tb

PAROC WAS 50

PAROC WAS 50t

Windproof insulation

PAROC WPS 1n

PAROC WPS 3n

Thermal insulation of plaster facades

PAROC Fatio

PAROC Linio 10

PAROC Linio 15

PAROC Linio 18

PAROC Linio 20

PAROC Linio 80

Thermal insulation for sandwich panels

PAROC COS 5

PAROC CES 50C

PAROC CES 50CS100

PAROC COS 10

Thermal insulation of flat roofs

PAROC ROB 60

PAROC ROB 80

PAROC ROB 80t

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Soundproofing and sound-absorbing materials

What is the difference between sound insulation and sound absorption?

Soundproofing is measured in decibels, a term used when talking about reducing the volume of outgoing/incoming noise.

Sound absorption is assessed by calculating the sound absorption coefficient and is measured from 0 to 1 (the closer to 1, the better). Sound-absorbing materials absorb sound inside the room and dampen it, resulting in the disappearance of echoes.

If you need to get rid of the noise from your neighbors, you need soundproofing materials. If you need the absence of echo in the room, sound-absorbing ones.

How to reduce noise from neighbors above/below/behind the wall? Is it possible to rid them of my noise?

Soundproofing the ceiling is obviously a losing option. The maximum reduction that can be achieved is from 3 to 9 dB. Try to come to an agreement with your neighbors and soundproof the floor for them, then you will achieve a reduction of up to 25-30 dB!

The sound insulation of a wall depends on the type of wall. They are either under construction or already existing (between rooms and apartments). For erected walls, immediately make double, independent frames. The thicker and more multi-layered the wall, the higher the chance of achieving a noise reduction of 50-60 dB in the apartment.

For existing walls, either make a frame filled with soundproofing materials, but be prepared for it to “eat up” 10 cm of space. Or, if space is limited, attach soundproofing panels or rolls of material directly to the wall.

To soundproof the floor, place materials such as TOPSILENT DUO or FONOSTOP BAR under the screed. If it is not possible to raise the floor under the screed by 10 cm, then lay soundproofing materials under the floor covering. Please note that in this case the noise will decrease by no more than 10-15 dB.

Try to ensure that the screed and flooring do not come into contact with the walls of the premises. The “floating” design provides better sound insulation properties. Conversely, if the soundproofing layer extends a couple of centimeters onto the walls, this will additionally dampen the sound waves.

We made repairs, didn’t think about soundproofing and now we hear noise from our neighbors, how can we fix it?

Unfortunately, you will have to make changes to repairs that have already been made.

If soundproofing of the floor is necessary, remove the laminate (or other finishing coating) and lay the FONOSTOP DUO soundproofing membrane underneath.

If there are walls, then, as mentioned above, the covering must be removed, a frame must be made and a material like TOPSILENT BITEX must be glued. Likewise for the ceiling.

What materials should be used to soundproof an apartment? How many do you need? How to calculate the required quantity?

Soundproofing an apartment requires an integrated approach. A structure is assembled, a “sandwich” of several materials. The thickness of a high-quality structure is about 7-10 centimeters.

To calculate the required quantity, send the dimensions of the room - length, width and height, the manager will make the calculation and tell you what materials will be needed.

What materials are needed for a recording studio?

For a recording studio, both types of materials are important and needed - soundproofing and sound-absorbing. First of all, high-quality sound in a studio is achieved through the use of sound-absorbing, acoustic panels made of melamine foam or open-cell polyurethane. The cellular structure of the material “quenches” sound vibrations. We recommend using thick panels up to 100 mm, this will ensure sound absorption in a wide range of frequencies. In addition, install “bass traps” up to 200-230 mm thick.

With sound insulation, everything is simple - more layers and it is advisable to use two-layer materials with a lead layer, for example, AKUSTIK METAL SLIK.

Which sound insulation is better?

The best material is the one that solves the problem. The same soundproofing materials manifest themselves differently depending on the volume, type of walls, and ceiling of the room. We recommend that you consult with a specialist before you begin any repairs.

How is soundproofing and sound-absorbing materials installed?

The easiest way is to attach sound-absorbing acoustic panels. Take any type of glue and attach it wherever you need it. The material is light and easily adheres to the surface.

For the installation of soundproofing materials, specially designed adhesives are used - OTTOCOLL P270 (for floors) and FONOCOLL (for walls and ceilings).

Do you deliver materials? Is there pick-up?

Yes, we deliver. Choose a convenient delivery method: pickup from a warehouse in Lyubertsy, delivery by van within the Moscow Ring Road and Moscow region (up to 100 km) or a transport company if you are far from Moscow.

Where can I see prices?

The price list for soundproofing and sound-absorbing materials is in the “Price Lists” section.

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Vertical sound-absorbing materials for improved acoustics

To create an optimal sound environment It is necessary to use different types of sound absorbers. A sound-absorbing ceiling significantly reduces the sound pressure level and sound propagation in the room. However, bare walls will create an echo effect.

Vertical sound absorbers reduce echo and improve speech intelligibility so you can hear what people say clearly.

Required number of vertical sound absorbers will depend on the characteristics of the premises itself and the type of activity carried out in it:

In open offices It is important to prevent the spread of speech and noise so that it does not disturb employees.

In schools Students need a supportive learning environment that allows them to hear the teacher and each other well and have the opportunity to think in silence.

In medical institutions patients need peace to rest and recover, and staff also need to be able to communicate.

Read more in the “Acoustic Solutions” section.

Acoustic parameters and their application

Reverberation time (RT) is the most commonly used parameter for calculations and measurements in room acoustics. The Sabin formula or its derivatives are also commonly used. This formula is easy to use, since you only need to know the volume of the room and the amount of sound-absorbing material, calculated through the statistical sound absorption coefficient αp. However, these formulas are suitable for ideal conditions with diffuse sound fields. In reality, the sound field is far from uniform. It can be represented in the form of two fields: non-diffuse and diffuse.
				Non-diffuse sound field			Diffuse sound field

Non-diffuse sound fields are predominantly located in the mid- and high-frequency region and contain sound energy that is distributed in a plane parallel to the sound-absorbing surface (usually the ceiling). The reverberation time in a room is determined by the non-uniform sound field. This means that the practical value of reverberation time is significantly higher than the theoretical value calculated for a diffuse sound field.

The best way to reduce energy non-diffuse sound fields is sound absorption by wall-mounted sound absorbers. Sound energy can also be redirected to a sound-absorbing suspended ceiling by reflection or dispersion from furniture, equipment, and room cladding.

Breaking up the sound-absorbing area into small elements interspersed with a solid surface will increase diffusion and slightly reduce reverberation time.

Additional benefits of vertical sound absorbers

In many rooms for good acoustics it is necessary to reduce the noise level. The more sound-absorbing material, the correspondingly lower the noise level. Scientists have proven that reducing sound pressure levels (lower noise levels) in a room leads to a decrease in psychological stress - people begin to speak more quietly.

For rooms where Speech intelligibility is a priority, and C50 is more important than reverberation time. Although STI is partially dependent on reverberation time, it correlates better with the amount of sound-absorbing material in the room. Adding sound-absorbing panels to walls reduces reverberation time and improves speech privacy, which also results in lower sound pressure levels.

By the number of sound-absorbing materials The level of speech privacy and the level of sound pressure reduction can be calculated, but the reverberation time (RT) cannot be calculated, depending only on the amount of sound-absorbing materials.

Practical solutions with vertical acoustics

The main three factors that should be taken into account when installing sound-absorbing wall panels in a room are:

area that can be lined with sound absorber

mechanical strength requirements

aesthetic requirements

The first and easiest way is partial covering of walls with wall panels. From an acoustic point of view, it is best to install wall panels on two adjacent walls to avoid the effect of fluttering echoes.

Another way to install wall panels- break them into small sections and distribute them evenly along the wall. This can be done either geometrically or in any order. This way you can create your own unique design.

Another simple and functional way to place sound-absorbing material in classrooms or offices - installing a horizontal belt of wall panels at a height convenient for human height and using them as an information board. In this case, it is also preferable to install panels on at least two walls in combination with a sound-absorbing ceiling.

Concrete floor in the garage - what brand, thickness of the concrete screed, how to concrete it correctly and inexpensively, how to make it and level it, foundation structure

Do-it-yourself acoustics modification.

You have a pair of speakers on your hands, or maybe not a pair. Active or passive. Floor or shelf. It might even be a subwoofer and not speakers.

This article will help you learn about ways to improve the sound quality of your acoustics without extra costs. The most effective methods for improving acoustics will be described, which are easy to implement with your own hands. This can be called polishing what the manufacturer could not implement, due to the feasibility of production and its payback.

All instructions and tips from this article are suitable for any acoustics with a bass reflex, including subwoofers and floor-standing speakers. Many tips will also apply to other types of speaker systems.

So, let's begin.

Upholstery of the body with sound-absorbing material and strengthening of the structure.

First, let's find out for what purposes this procedure is being performed.

Opening the columns.

Disassembling the column is very simple.

If this is an active speaker, then on the active speaker you need to unscrew the amplification unit from the back, which is screwed on with screws.

You need to remove the block very carefully, without sudden movements. If there are plugs that come unfastened, disconnect them and place the amplifier unit nearby without over-tightening the wires. On passive speakers, you just need to unscrew the screws on the midrange speaker and carefully remove it without damaging the wires.

*All these operations must be carried out carefully and without sudden movements, in order to avoid damage to wires and circuits.

Strengthening the body.

This modification is worth carrying out if you doubt the structural strength of your acoustics and there are no additional rigidity structures inside the case (reinforcing strips, “plugs” on the walls, screeds between the walls). Almost always, speakers need additional strengthening.

For this procedure you will need small 1x1 - 1x2cm bars and rubber glue. We will glue the bars along the corners, on which there are no bars, which will strengthen the fit of the side walls to each other. We measure and cut, apply and estimate, spread plenty of glue on the beam and the place to which it will stick. We glue over all the corners where the manufacturer saved wood. Naturally, we use the beams as spacers, and not just glue.

It is also worth laying beams along long walls columns, if missing. As shown in the picture, or diagonally. The beams should fit snugly at the edges.

It is also advisable to make horizontal struts between the walls, this will significantly strengthen the structure. This is especially true for large speakers with long walls (for example Microlab Solo 7).

After this procedure, we get a stronger structure that creates less resonance of the walls, as well as less vibrations when micro-friction and walls touch each other.

To carry out this procedure, we will need double sided tape And sound-absorbing material.

For which goals it's being done.

All this action is carried out with the purpose reduce reflection of sound waves from an acoustic body with a bass reflex. If this is not done, then often, instead of bass, incomprehensible buzzing and whistling sounds will come out of it. Upholstery gives more smooth And balanced bass which is becoming more soft and better audible. It removes the buzzing, resonating sounds that arise in the acoustic body due to the collision of sound waves. This also allows you to slightly expand the lower range of reproduced frequencies.

As sound absorbers, the best materials are: padding polyester(can be found at any clothing market, or can be found in an old jacket :) felt, rolled wool or the most interesting material - cotton wool, sound-absorbing – type “ URSA”, besides, it is non-flammable. Just not insulating glass wool made from quartz sand, but homemade wool for installing partitions. If obtaining these materials is problematic, as a last resort you can use rolled foam, which you can get at any HozMage. But its use is still highly undesirable. Do not forget that padding polyester, felt, cotton wool must be fluffed before gluing.

To begin with, we take out the sound-absorbing material that the manufacturer put inside, if any.

What are we doing.

1) We glue with double-sided tape as much of the area inside the column as possible. Immediately peel off the protective paper.

2) We cut or stretch the sound-absorbing material so that the bare walls are completely covered, including (especially) the corners.

3) We line all the cavities with material so that the wooden walls are completely sealed. The thickness of the layer should be no more than 2 cm, otherwise it can significantly reduce the volume inside the case, which will not have the best effect on the depth of the bass component.

Warning.

In areas that get hot, it's best not to overdo it. This applies to places near the transformer and amplifier unit. It is better to leave an empty space of 1-2 cm between them and the sound-absorbing material. Therefore, the best material is non-flammable sound-absorbing wool like “URSA", which, for example, may remain after repairs. It can be used without restrictions.

You need to try to fix the material as thoroughly as possible. After all, you don’t want cotton wool or synthetic padding to jump around inside or, even worse, fly out of the bass reflex during large movements of air masses inside the housing :)

Modification of the bass reflex.

To reduce rattling and possible whistling from the bass reflex, it is worth doing 2 things.

1. Wrap the bass reflex with sound-absorbing material, like a “fur coat,” in one layer. Leave 1 cm of bare space at the end of the bass reflex. Secure the “fur coat” tightly with thin elastic bands, wrapping them around the bass reflex, as shown in the figure above.

2. Using wire cutters, cut off any protective grilles inside the bass reflex pipe evenly. There is no benefit from them, but there are a lot of unnecessary sounds and whistles. If there is a mesh glued to the end, then it is also better to remove it. This will allow air to flow more easily, which will increase the overall responsiveness of the speaker.

Installation of acoustics on spikes.

Try pressing the speaker for a while while playing music. You will hear that it will be out of tune and swallow a good half of the frequencies. This happens because the finger absorbs vibrations, preventing the speaker from releasing them into the air.

Speaker housing is a continuation of the speaker. When it comes into contact with the floor, table, shelf or other things, the speaker body gives off some of its vibrations to these objects, as in the example with a finger.

In order for the acoustics to efficiently transmit sound waves into the air without physically scattering them on the floor and objects with which it comes into contact creating distortions, spikes are used.

The spikes are attached as legs. To do this, 4 small holes (not through) are drilled on the bottom wall into which they are screwed. You can buy them in many consumer electronics stores that sell acoustics and accessories, or order them online. Under acoustics with spikes, there must be hard material– ceramic tiles, parquet or other. The main thing is that the legs have as little contact with it as possible and were not recessed.

The principle of action of the thorns is that they strongly reduce the contact area columns with the surface on which it stands. Thanks to this, the sound waves that are supplied to the body begin to sound, and not fade away on the floor, parquet or shelf. Distortion is reduced to a minimum, the bass component becomes more audible and much more detailed.

Important note.

Spikes make sense to use for acoustics with decent weight and a decent size. Spikes should be used primarily for floor-standing acoustics weighing more than 12 kg. Or for subwoofers weighing 5 kg or more. In smaller acoustics the effect will be there, but not as noticeable.

Replacing wires on the amplifier part of the acoustics. For active acoustics.

Often, the manufacturer saves on such things as the quality of wires from the crossover to the speaker and from the board to the crossover. The thickness, as well as the quality of the wire, directly affects the sound quality. The thicker the wire, the deeper the bass and the clearer the mids. This modification should primarily be carried out on subwoofers, due to the greater energy that flows through these same wires.

1. We select a suitable replacement wire, naturally the highest quality copper that is available. Preferably not VVG (solid), since the signal changes when passing through such a wire. It is better to take a PVA (braided) core made of oxygen-free copper. Thicker is not always better, you need something in between, depending on the power of the acoustics.

2 . Unsolder and cut off the old wires. If there is a bracket at the other end, then, if possible, solder the wires to the terminals themselves on the board. If this is not possible, cut off the bracket at the root, remove the terminals, solder the wires to them and insert them back into the bracket. We also wrap the speaker and crossover terminals and solder them liberally. Soldering is a MUST!

3. We make sure the quality of the soldering.

It is also worth paying attention to connecting wire between the columns.

The manufacturer rarely slips in something sensible. The best option among the most affordable ones is braided wire with transparent insulation, which is supplied with, for example, SVEN Royal or Microlab SOLO 6 and higher.

A similar wire can also be purchased at electrical stores. This is like an inexpensive option for replacing the flimsy wires that come with the speakers. For floor-standing options, speaker wires with a thicker cross-section and higher quality, oxygen-free copper are best suited. These can be bought at any store that sells home theaters, or at the electronics market.

A few words about the wires from the sound source to the acoustics.

The wires that go from the sound source to the speakers (usually tulips) or receiver must be of good quality.

It is highly desirable that they be shielded from interference from power lines, cellular networks and radio. To do this, wire manufacturers wrap them in a layer of foil, or braid them with aluminum or copper thread. It is not difficult to distinguish them - they are much thicker than non-shielded ones. Also, high-quality wires should have gold-plated plugs for lower resistance and less signal loss on the plugs. You can buy such wires on the radio market or in stores that sell home theaters.

Note.

In order to have a noticeable effect from changing the wires, we recommend replacing them on acoustics with a price level 100$ and higher (for 2.0). Or, if the wire used by the manufacturer is of really poor quality.

Use surge protectors.

Good surge protectors that are equipped high frequency suppressors, they are quite good at cleaning up the so-called White noise and other interference caused by poor power supply and network interference.

Often, in built-in amplifier circuits, there is no high-quality noise suppression circuit, which leads to distortions, noise from speakers and different sounds when the refrigerator starts working or the neighbor’s electric stove starts igniting :)

Remember that cheap filters will not save you from interference. These are capable of protecting equipment from pulse currents that arise, for example, when lightning strikes the wiring, and nothing more.

The filters that we need must contain a suppressor (filter) of high-frequency interference. They are also useful for receivers and amplifiers, both for protection and for better noise immunity.

Companies make good filters ZiS Pilot(starting from series G.L.), APC.

If the speakers hum or there is strange sound coming from them.

There are usually two reasons:

• Poor quality signal source or cable.
• Poor quality input capacitors in the built-in amplifier part (if the speakers are active).

IN first case, you need to check the cable, look inserted Are there connectors? fully into the plug and check integrity cables Also need take away wires from others, especially cables supply network And radio, since they create magnetic fields around themselves.

In second case, you need to open the column with the amplifier part. It is usually heavier and has a heatsink.

Next you need to find the capacitors of the power supply filtering circuit. Usually there are two of them and they are the largest. They should be removed and replaced with new, high-quality ones with a higher maximum voltage and capacity. It is also worth looking to see if others are swollen or leaking (brown or yellow dried liquid nearby). If yes, then replace it without hesitation.

You can also replace other large capacitors, since they do not stand out in terms of quality in multimedia acoustics.

Other useful tips for improving the sound quality of your acoustics, without any modifications.

Correct placement of acoustics.

To achieve the highest possible sound quality, the acoustic system needs arrange correctly around the room.

30% of success in achieving the correct sound picture depends on the correct placement of acoustics.

_________________________

1. Tweeters ( HF) - must be flush with the ear listener for better positioning in space.

2. Port the bass reflex should not be anything closed. The distance from a wall or other obstacle should be more than 15 cm so that low frequencies are not lost at the output and nothing prevents them from spreading throughout the room.

3. The front speakers should be positioned at 30 degrees, from the listener’s point of view and directed strictly at him.

Rear, on 30 degrees from the listener's side point (from 90 degrees) Only in this case the best depth of the sound picture is ensured.

4. Optimal distance, on which the speakers should stand from the listener - 2 meters For floor speakers and 1 meter For shelf.

5. Eliminate extraneous sound sources. This could be an open window, a quiet system unit, and so on. All these sounds interfere with the perception of sound and can even make a great sound illegible and poorly detailed.

Conclusion.

Let's repeat the steps again:

1. Strengthen the overall structure.

2. Upholster the body with sound-absorbing material inside.

3. Modify the bass reflex.

4. Install the acoustics on the spikes.

5. Replace the wires inside and outside with better ones. Connect through a good surge protector.

6. Correctly arrange the acoustics, eliminate noise sources.

7. Listen.

Most of these tips are suitable for both active and passive acoustics.

Get creative and be surprised how the sound changes for the better.

Happy modification!

The decline in amplitude-frequency characteristics in 100-liter speakers begins at approximately 60 Hz; to ensure high-quality sound from 30 Hz, a speaker volume of 400 liters is required. These contradictions are illustrated in Table 1

Table 1. LIMITING REQUIREMENTS AND MODERN ACCURACY OF SOUND REPRODUCTION.
Main parameters.	Numerical recording and reproduction of electrical signals in the audio range.	Limits of human capabilities.	World-class electroacoustic transducers (output speakers) MONOLITH-111X	Domestic speakers 35-AC (running for music lovers)	The best domestic speakers 3 SL-113
Frequency reproduction bandwidth, Hz.	10-20000	16-22000	28-24000	50-20000	63-25000
Frequency response unevenness, dB.	0.5	0.5	+ / - 2	+ / - 5	+ / - 3
Nonlinear distortion (clear factor), %.	0.005	0.05	1	12	2
Dynamic range, dB.	90	120	120	100	110
Preferred volume (dynamic range), dB.	-	80 for amateurs. 90 for professionals	-	-	-
Volume, liters.	-	-	380	70	125
Cost, US dollars.	500	-	7000 per pair	300 per pair	500 per pair

As you can see, even in very expensive speakers with a volume of up to 400 liters, the entire octave is unsatisfactorily reproduced - 16:32 Hz, and harmonic distortion is 20 times higher than the permissible values. In mid-priced speakers with a volume of 60:100 liters, the second octave is unsatisfactorily reproduced - 32:64 Hz and the first is practically absent, while harmonic distortion exceeds the permissible limit by 50:100 times.

The last word in solving this problem is the active subwoofer - a separate loudspeaker designed to reproduce exclusively the low-frequency region of the sound spectrum. The dimensions of such subwoofers range from 70:40 liters, the frequency range is usually 30:150 Hz, but the “sweet-voiced” speakers for it do not exceed 10:12 liters. The increase in low frequencies in subwoofers is ensured by forced amplification modes built into the amplifier, which inevitably gives rise to an increase in harmonic distortion. To match the subwoofer with a pair of standard speakers, a special digital filter is required - all together leads to a price of about 500 US dollars.

As we can see, improving the acoustic performance of small-sized speakers using sound absorption inside the box remains attractive.

The proposed new original technical solution for the formation of a sound-absorbing environment can significantly simplify the situation. An experimental decrease in sound pressure in such an environment was obtained by up to 50 times. In addition, the sound-absorbing medium, compared to air, has a significantly higher viscosity; this quality, combined with the ability to reduce sound pressure, has the most favorable effect on the suppression of numerous resonances in the box, i.e. leads to smoothing (straightening) of the amplitude-frequency response and reducing harmonic distortion. There are no restrictions on the dimensions and shape of the absorbing medium, or on the amount of sound pressure.

A modern acoustic system usually contains 3 electroacoustic transducers: high-frequency, mid-frequency and low-frequency (woofer). The first 2 converters do not require large volumes for high-quality sound reproduction, therefore they are supplied already enclosed, and the woofer requires large volumes, so its housing is the body of an acoustic speaker. The new technical solution will make it possible to reduce the physical dimensions of the woofer housing to the size of the woofer itself and opens up the possibility of supplying it also packaged, in which case special requirements for the speaker system housing disappear.

For example, housing a 10-inch woofer with 6 liters of sound-absorbing media provides the following characteristics:

• Frequency range (with unevenness of 0.5 dB and a decline of 31.5 Hz-6 dB) - 31.5...1250 Hz.
• Maximum acoustic pressure - 110 dB.
• Harmonic distortion at 90 dB - 0.5%

The research results are illustrated by graphs in Fig. 1 and Fig. 2, from which it follows that, in comparison with a modern subwoofer, the reproduction of low frequencies using the proposed solution is half an octave deeper, even with a closed-type acoustic design; the diffuser experiences a pneumatic load no more than in free space, the medium is viscous, as evidenced by the disappearance of the speaker system's own resonance - all this ensures extremely low harmonic distortion. If you take into account that the new technical solution provides dimensions that are an order of magnitude smaller, does not require an amplifier and an expensive digital filter, and provides a price several times lower, then you involuntarily begin to join in with those who believe that modern subwoofers are a “step to the side” : "a gesture of desperation born of the awareness of the serious limitations in achieving the deepest bass using classic loudspeaker systems." The real way to solve the problem of deep bass is opened by Russian patent No. 2107949 for the invention “Device for high-quality sound reproduction.”

Having dug through a bunch of literature, articles and surfed the expanses of the multilingual Internet, I still haven’t found a sensible answer. Books and articles, as a rule, give an approximate assessment of the results without specific arguments and firm conclusions. Any discussion of this issue on forums leads to multi-page squabbles among the participants, again without arguments and results that would allow one to make a choice. And somehow, completely unexpectedly, in the vastness of the Dutch network, I discovered an excellent and unique article on the topic. Everything was there - measurements, graphs, detailed comments and conclusions from the author. Well... not many people speak Dutch, but it would be very nice if Russian-speaking craftsmen could finally get a comprehensive answer to such an important and difficult question. I took on the translation.

Introduction

To create good acoustic systems (AS), you first need a good enclosure. The speaker housing provides the necessary concentration (directionality) of acoustic energy. Ideally, the speaker enclosure should be absolutely rigid and not exposed to acoustic energy. The most common case material is wood. Other materials such as plastic, aluminum, stone and concrete are also used. A large number of speakers have sound problems due to the fact that their cabinets impart their own coloration to the sound, since they themselves emit almost as many sound waves as the dynamic head itself. This effect appears at certain frequencies and clearly shows itself. What's really going on?

What's really going on?

The dynamic head (DG) installed in the speaker cabinet vibrates in time with the input signal coming from the power amplifier. These vibrations are transmitted through its DG basket to the speaker body and lead to vibration of the entire structure as a whole. Another way of vibration transmission is due to the rapid compression and expansion of air inside the speaker housing in time with the stroke of the DG diffuser (piston effect). These vibrations are very small in amplitude and are difficult to detect visually or by touching the body with your hand. In an ideal case, the DG has no contact with the speaker body and does not exert acoustic pressure on the walls of the box - the speaker system sounds like a separate DG. In practice, this, of course, is unattainable, and the most important role in the sound of speakers is played by the material and design of their cabinets. This question worries me, like any other manufacturer of quality speakers, above all. And in order to be able to choose the best material for building speakers, I carried out an experimental study of them.

Measurement technique

How to test a wide range of materials?

A special technique has been created for measurement. A housing (like a closed box with a flush-mounted speaker) was constructed from 18mm MDF reinforced with a 32mm layer of concrete. The weight of the finished test box body was 105 kg.

The thickness of all the studied panels is thinner than the walls of the experimental box, thus forming the weakest link in the structure for measurements.

The front part of the test box has a frame for installing the panels under study into it.

To make it possible to measure panels with stiffeners, a removable rib is installed in the center of the opening under the test panel.

Description of the technique

First you need to find a place to carry out control measurements.

The control measurement is carried out without installing the test panel in the experimental building.

The second measurement is carried out in the same way, but with the test panel installed and we see the difference in the spectra, as shown in Figure 1.

If we do not make any changes in the second dimension, then accordingly we should not see any difference between the spectrograms.

The measured difference is the reduction in sound pressure by the test panel.

That is, in the ideal case (ideal material for the speaker enclosure) in the second dimension (with the panel installed) we should not see any frequency spikes in the spectrogram (similar to the one in Figure 2).

To exclude the influence of the ambient noise level, the latter was measured at a higher sensitivity of the system (Figures 2, 3).

Measurement results

In all cases, the same settings were used.

In order to exclude the possible influence of space, measurements were taken at a short distance (17.5 cm) opposite the center of the test panel.

sampling frequency 2kHz - 6kHz

level -14dB

3D roll-off, dynamic range +5/-35dB

Part one
1. Basic measurement	2. Noise level
3. Noise level -70dB	4. 10mm chipboard
5. 18mm chipboard	6. 18mm MDF
7. 18mm meranti plywood	8. 18mm birch plywood
	10. 18mm birch plywood with stiffeners
11. “Sandwich” chipboard + birch plywood	12. “Sandwich” chipboard + MDF
13. “Sandwich” chipboard + birch plywood + foam	14. 18mm MDF + 20mm concrete
15. 18mm MDF + 20mm concrete + stiffeners	16. 18mm MDF + concrete + stiffeners + 80mm glass wool

Part two
17. 80mm glass wool	18. Solid birch with stiffening ribs + 80mm glass wool
19. 18mm MDF + 10mm mineral wool	20. 30mm solid wood without stiffeners
21. 18mm MDF + 7mm isomat without stiffeners	22. “Sandwich” 18mm solid birch + 7mm isomat + 18mm MDF + stiffeners
23. 18mm MDF + 11mm isomat without stiffeners
25. “Sandwich” birch + 11mm isomat + 18mm MDF	26. “Sandwich” birch + 11mm isomat + 18mm MDF with stiffeners
27. “Sandwich” solid wood + 11mm isomat + 18mm MDF with stiffeners	28. “Sandwich” birch + 11mm isomat + 18mm MDF with stiffeners + 80mm glass wool

1. Basic measurement

Two identical basic measurements that show zero difference between each other. In practice, this is not entirely possible, because small fluctuations in the sound pressure from the DG are always present. This difference is very small, but it is there.

2. Ambient noise level

In the second dimension, the test for no signal is passed. The ambient noise level was measured here, with the same sensitivity as all other measurements.

3. Ambient noise level (-70dB)

Same conditions as in the second measurement, but with adjusted sensitivity. Here you can see disturbances in a wide range of frequencies.

4. 10mm chipboard

A strong resonance is observed at 140Hz with a force of + 4 dB, which is almost comparable to the sound pressure of the DG. Second and third resonances at 350 and 600 Hz with longer decay times. And the last resonance lies in the 1200Hz region.

5. 18mm chipboard

For a thick chipboard sheet, the first resonance rises to 175 Hz, the second is in the 500 Hz region and almost merges with the third at 580 Hz.

The first resonance, compared to a 10mm chipboard sheet, is slightly reduced, but the resonance at 580 Hz is stronger. Higher frequency resonances at 820 and 1200 Hz are also slightly enhanced.

6. 18mm MDF

This spectrogram is completely identical to 18 mm chipboard. All resonances are at the same frequencies and have the same strength.

7. 18mm Meranti plywood

Meranti plywood has approximately the same resonances as chipboard and MDF. The first resonance shifts from 175 Hz to 205 Hz and has a longer decay time. The resonance at 580 Hz goes beyond +5dB and also decays more slowly. The measurement results showed that this material is of little use for high-quality structures and is not of interest for further measurements.

8. 18mm birch plywood

This spectrogram is worth examining in more detail.

The first resonance shifts higher to 230 Hz and is weaker than that of Meranti plywood. The second returned to 580 Hz, and increased to +10 dB.

Resonances in the 850 and 1200 Hz region decreased to -6 dB.

Resonances also appeared from 1930 to 1990 Hz with rapid attenuation to -35 dB. Resonances below 20Hz are damped less than those of chipboard or MDF and have a level of -15 to -25dB.

9. 18mm MDF with stiffeners

The first resonance has practically disappeared, compared to unreinforced MDF.

The resonance strength at 175 Hz dropped from -2 to -30 dB. A new resonance has been added at 300 Hz -10 dB. The strong resonance at 580 Hz, which reached +7 dB for the unreinforced panel, has now been reduced to -7 dB. The remaining resonances have not changed, and another one has been added at 980 Hz, which is weaker than the others, but has a longer decay time.

10. 18 mm birch plywood with stiffeners

The first resonance at 230 Hz, which was on 18mm plywood without reinforcement, was greatly weakened. Now it has shifted to 300Hz. There is no such noticeable decline in resonance at this frequency as in the case of MDF reinforcement (from -2 to -20 dB).

There is no second resonance, but there is a new peak at 490 Hz with a strength of up to -7 dB. At higher frequencies we observe the same picture as for MDF.

11. “Sandwich” 18 mm birch plywood + 18 mm chipboard

The panel is significantly enhanced, and in the graph we see a combination of two different characteristics. The first resonance is practically eliminated. The strong fourth resonance corresponds to the same stronger resonance on chipboard and birch around 580 Hz. The remaining resonances are quite identical to those on separate panels made of plywood and chipboard.

12. “Sandwich” 18mm chipboard + 18mm MDF

Chipboard and MDF have the same characteristics. The first resonance is transferred to the “sandwich” from the previously discussed separate panels. The remaining resonances are generally similar to the characteristics of the previous “sandwich” (dimension 11). The increase in attenuation of resonances in the “sandwich” version is approximately proportional to the increase in the thickness of the panel as a whole, compared to individual 18mm chipboard and MDF boards.

13. “Sandwich” 18mm chipboard + foam + 18mm plywood

The first resonance is weakened compared to a similar “sandwich” without foam. This occurs due to the isolation of the elastic layers of the panels from each other.

14. 18mm MDF + 20mm concrete without stiffeners

The graph shows that the first resonance, present on pure MDF at a frequency of 180 Hz, weakened slightly (-4 dB) and shifted to 130 Hz. The remaining higher frequency resonances decreased significantly. Concrete had a strong influence over a wide range of frequencies.

15. 18mm MDF + 20mm concrete with stiffeners

The first resonance was significantly reduced. The remaining resonances also weakened, by an average of 10 dB. However, due to the stiffener, a strong resonance appeared at 500 Hz.

16. 18mm MDF reinforced with 20mm concrete and stiffeners with glass wool damping placed between the DG and the test panel.

The strong resonance at 500Hz is now significantly reduced (by about -10dB).

17. An 80mm glass wool slab lying freely in the opening of the test box.

It shows which frequencies are attenuated by glass fiber placed between the DG and the measuring microphone.

18. 18mm birch plywood with stiffeners + 80mm fiberglass

Excellent damping of almost all resonances, giving a picture that many high-quality speakers would actually like to see. The resonance at 400-500Hz weakened to -15dB.

19. 18mm MDF with glued 10mm sheet of pressed mineral wool

The weakening of resonances is easy to detect, compared to pure MDF (measurement 6). It can be seen that the mineral wool sheet generally improves the picture, but the attenuation of the strongest resonances is not very large - the first at 160 Hz is -10 dB and the second at 600 Hz is only -2 dB.

20. Solid deciduous wood 1 30mm without stiffeners

Typical test results for 30mm panels made from solid hardwood are presented. The first resonance at 210 Hz is quite strong (up to -9dB) and has very poor attenuation. There are fewer resonances at higher frequencies and they are much weaker in intensity (on average up to -23dB)

21. 18mm MDF + 7mm isomat 2 without stiffeners

The first resonant frequency compared to pure MDF dropped to 100Hz due to the increase in the mass of the test panel. In intensity it reaches -5 dB. Resonances at higher frequencies are damped much better compared to MDF (measurement 6).

22. 18mm MDF + 7mm isomat with stiffeners

The first resonant frequency rose significantly from 100 to 400 Hz. There is a significant decrease in its intensity from -5dB (for pure MDF) to -15dB. The result of using this combination of materials with the use of reinforcement is very productive.

23. 18mm MDF 11mm isomat without stiffeners

The first resonant frequency is also reduced due to the increase in weight compared to pure MDF. This resonance is now located at 105 Hz and is attenuated to -12 dB. Resonances at higher frequencies have similarly weakened compared to measurement 6. In general, for the 11mm isomate the results are slightly better than for the 7mm isomate.

24. 18mm MDF + 11mm isomat with stiffeners

Almost the same patterns as with a 7mm isomat in dimension 22. The results have improved somewhat due to an increase in the thickness and weight of the panel. The resonance at 400 Hz has a level of -17 dB.

25. “Sandwich” 18 mm MDF + 11 mm isomat + 18 mm solid birch without stiffeners.

An almost “clean” picture, no more pronounced resonances. Over the entire frequency range, the attenuation of resonances is 35 dB or more. There are only four small resonances of -25 dB at frequencies 340, 700, 1K and 1.5 kHz. Of all the measurements, only concrete (dimension 16) was slightly better.

26. “Sandwich” 18mm MDF + 11mm isomat + 18mm solid birch with stiffeners

This combination is largely similar to measurement 24. In principle, I expected some improvement in the results of measurement 25. But we got a slightly worse result, which is likely due to the way the test panel was mounted.

The most likely causes of deterioration are as follows:

The inner surface of the box is insulated from the outer surface with a layer of isomat;

The stiffening ribs inside the box must be glued directly to the inner surface of the panel under study;

During test measurements, I could only use screws (no glue) to attach the panel and stiffeners to be able to take multiple measurements;

The inner panel is attached using a birch stiffener;

In this case, the mounting base is MDF + isomat with screws;

It was impossible to secure an additional stiffener to the tested panel, since the screws would create an additional path for transmitting resonances to the outer layer of the “sandwich”

This is the result of direct transmission of vibrations from the inner layer to the outside;

The isomat lost its insulating character, resonances spread around it;

The outer layer of MDF and the isomat are attached at the edges and the fabric is adjacent to each other in the center of the panel.

27. “Sandwich” 18mm MDF + 11mm isomat + 30mm layer of hard deciduous wood with stiffeners

Here the 18mm layer of birch is replaced with a 30mm layer of hardwood.

This combination has the same problems as above (dimension 26).

In total, the result looks even worse than the previous one.

28. “Sandwich” 18mm MDF + 11mm isomat + 18mm solid birch with stiffeners + 80mm glass wool

This dimension should have been virtually identical to the 26th dimension since only fiberglass was added. You can see that the result turned out better than expected. Over the entire range, the attenuation of resonances is -35 dB, and only between 300-500 Hz there are 2 small resonances at a level of -27 dB. This result is the best of all measurements, surpassing even concrete. The improvement in results compared to measurement 26 was probably due to better fixation of the test plate. In the final measurement, even larger screws were used to secure the panel to ensure the greatest possible degree of pressing against the body of the test box.

Conclusion(for the first part)

During the measurement process, the tendency for improvement/deterioration of results was constantly monitored. If the result with the new material turned out to be worse than the previous one, then no further experiments were carried out with it.

The thickness of the panel has a great influence on the level of resonances and their attenuation - the thicker the panel, the faster the attenuation occurs.

The first resonance is always reduced by increasing the thickness and weight of the panel.

Insulating the plates with an elastic layer (foam) has a negative effect on the overall picture of resonances. Therefore, I did not continue with rubber and other elastic materials as a layer.

The “sandwich” panels in all cases turned out to be better than the materials from which they were made separately.

The stiffening ribs located in the center of the test panel have a significant effect on reducing the first resonance.

Panels with a “sandwich” structure reinforced with stiffening ribs ultimately give the best results.

Excellent results are obtained by using stiffeners in combination with concrete. The entire spectrum of frequencies, except for the high range, deserves high praise.

Damping to reduce resonances at high frequencies allows you to suppress all resonances to a level of no more than -35 dB.

In practice, all these measures allow you to get an incredibly open sound without overtones. This can be clearly seen in all pauses and breaks in the signal.

Additions (based on the results of the second part of the measurements)

Each material combination produces a different reduction in audio frequency transmission.

The chosen direction of application in the construction of elastic isomat walls allows us to get as close as possible to the neutral characteristics of a test box made of MDF and concrete (i.e. to the ideal).

The influence of the tiny resonances observed in the last pictures could not be detected in the sound of the music, they were only detected with the help of sensitive measuring equipment.

At the moment I am working on creating the first prototype for a housing using isomat. 3

The construction of such cabinets is such a precise and complex process that additional research in this area is required to be able to use such structures in practice.

Notes (from the translator)

1 Unfortunately, the author of the measurements did not note what kind of wood he made the test panels from. Hardwoods: oak, beech, hornbeam, ash, maple, saxaul and others. It is possible that with the transition from one type of wood to another, significant changes in the observed picture do not occur.

ISOMAT) - (not to be confused with travel mats!) pressed soundproofing composite. It has high specific gravity, rigidity and hardness. Gives excellent results when soundproofing sheet steel, aluminum, wood and plastic.

The original article can be viewed here: www.hsi-luidsprekers.nl The author has done a truly colossal and useful job! If he sees... Thanks!

I hope that the translation of the article will be useful to many and, on the one hand, will put an end to multiple disputes, and on the other hand, will push our craftsmen to new exciting discussions, but this time substantive and with arguments.

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