Acoustic design does not mean decorating the speakers with carvings in an antique style, although this will give the speakers uniqueness, but solving the problems of acoustic short circuit.
The fact is that when the diffuser moves on one side, a overpressure air, and on the other hand the air is discharged. For sound to occur, it is necessary that air vibrations propagate into space and reach the listener, and in in this case the air vibrates around the dynamic head basket and the sound pressure it creates is not very high, especially in the low frequency region:
More details about the principle of operation of the dynamic head HERE.
Methods of breaking the acoustic circuit are called acoustic design, and each of them is designed to make it difficult for air to penetrate from one side of the diffuser to the other.
There are several main options for breaking an acoustic short circuit. The simplest one is to use sheet material in the middle of which a hole is cut for the dynamic head. This is called an acoustic screen:
A little more the hard way- open box, i.e. drawer without back wall:
Both of the above methods have too little efficiency, so they are practically not used only in cases where “there is no fish and no cancer.”
Much more efficient use closed box, and in such speakers Special attention pays attention to the tightness of the box - any gap in the box will produce overtones, since both a fairly large pressure appears in the box (when the diffuser goes inside the box) and a fairly large vacuum (when the diffuser moves out):
The next option for acoustic design is a box with a bass reflex:
In this case it is rectangular hole located in a strictly calculated location on the front panel of the speaker system. However, this option can also be done using a pipe:
The advantages of these options include increased output at the frequency at which the bass reflex is designed, the main purpose of which is to invert, i.e. change the phase to the opposite. As a result, sound is emitted into space not only by the front part of the diffuser, but also by the rear part, the phase of which is changed by the bass reflex.
A more complex version of acoustic design is an acoustic labyrinth. The essence of this option is that the passages inside the speakers are located in such a way that resonance occurs at a certain frequency and, as a result, a large increase in output at this frequency. The calculations and manufacturing accuracy of such systems should be taken VERY seriously, since there is a high probability of “standing” waves occurring in the labyrinth. In this case, the sound quality will be even worse than that of the option with an acoustic screen:
The horn version allows you to get even greater output at the resonant frequency:
The difference between a horn speaker and a labyrinth speaker is that the direction of the sound waves varies according to different laws- the horn either expands conically along its entire length, or exponentially. The labyrinth can have the same window along its entire length, it can expand or, on the contrary, narrow, but always linearly. In addition, for speakers with a labyrinth, both the front and rear parts of the diffuser take part in the work, while for horn speakers, both one and both sides can radiate.
The next acoustic design option is a bandpass or bandpass resonator:
This option differs from all previous ones primarily in that it emits only at the resonance frequency and requires strict adherence to the design dimensions.
The last three options are mainly designed for using a low-frequency dynamic head, while the previous ones are quite suitable for wideband speakers. Therefore, if the acoustic system has, in addition to woofers, others, for example, midrange and HF, then it is not recommended to embed them into the housing with the woofer.
In any case, to calculate the speaker sizes, you will need the characteristics of the dynamic head, in particular the Thiel-Small parameters. If this data is not available, it is necessary to obtain it before calculating the dimensions of the speaker housing. There are quite a lot of descriptions of methods for obtaining these parameters - just use any search engine.
Of course, these are not all types of acoustic design - these are the most popular.
The enclosure dimensions are calculated using special programs for calculating speaker enclosures. Finding them on the Internet, as well as instructions on how to use them, is also not problematic.
When designing speakers, you should take into account some technological features - if the front panel on which the speaker is installed is recessed into the housing, then you will need to make additional ribs into which the front panel will actually rest:
If you don’t want to mess around with the ribs, you can make the front panel so that it rests against the sides of the case, which also strengthens the connection between the front panel and the sides:
All this will give the front panel an additional, more rigid connection with the body.
You should also not forget about the methods of attaching the dynamic head to the front panel and the pitfalls that you may encounter. Mounting the speaker from the outside is most preferable, since it does not mechanically weaken the structure, but this method involves chamfering along the diameter of the dynamic head and sinking the speaker inside the housing so that ALL emitters, bass, midrange, and treble are in the same line. chamfering reduces the mechanical strength of the front panel and its restoration will require an additional ring secured from the inside. The relevance of this ring is the higher, the greater the power expected to be obtained from the speaker being manufactured, and at powers above 150 W it is already 100% necessary:
If necessary, you will need to remove the side chamfers on the ring so that it does not interfere with the front panel of installation into the case itself.
When installing the dynamic head, it is necessary to ensure that there are no gaps. If the chamfer is removed by a machine, the surface turns out to be relatively smooth; all that remains is to sand it. However, at home it is quite difficult to obtain a flat surface. It is not entirely clear what the manufacturers are doing here - it is strongly recommended to install the speaker from the outside, but the sealing rubber on almost all dynamic heads is located for installation from the inside:
To solve sealing problems, you can use door seals - self-adhesive strips of porous rubber, sold in all hardware stores. The sealant is glued along the perimeter of the chamfer and when installing the speaker, it completely fills all the cracks:
If the dynamic head is installed from the inside, then the hole will need to be chamfered to prevent the appearance of standing waves. However, such a chamfer weakens the rigidity at the point where the speaker is attached to the panel (the material is too thin) and this method of fastening is not acceptable for powers above 50 W without additional reinforcement of the structure:
It is advisable to use natural material for the manufacture of speaker cabinets, optimally plywood, but this material is too expensive. Therefore, it is better to use plywood to build medium and high speakers price category, using dynamic heads of VERY good quality and power above 100 W.
For the average price category and low powers (up to 50W), you can use fiberboard or MDF (the same as fiberboard, only the thickness and density is greater), but it must be processed and modified, or chipboard.
For powers up to 10 W, plastic is also quite suitable, but also using technological tricks.
The first problem when making speakers from plastic arises when eliminating the chatter of the plastic itself, especially manifested in the centers of the sidewalls. You can get rid of this unpleasant sound by using thicker plastic, or you can glue additional stiffeners. If the plastic is dissolved with dichloritane, then dichloritane with plastic chips dissolved in it can be used to attach the ribs. If the plastic is not dissolved by dichloroethane, then it is better to use epoxy glue, preferably made in Dzerzhinsk. Before gluing, carefully sand the contact areas with coarse sandpaper and do not be afraid that the glue forms beads at the point of contact of the parts to be glued:
For greater efficiency in suppressing overtones of the body, you can “paint” the resulting “baths” in 2-3 layers with anti-gravel - a coating used to cover the underbody of cars to protect against small gravel.
After drying, anti-gravel acquires the properties of rubber and absorbs sound quite well.
When using fiberboard as a material for the manufacture of speakers, it is necessary to determine the required thickness. If the speaker power does not exceed 5 W, then fiberboard can be used in one layer. Before cutting the fiberboard, it is coated on one side with epoxy glue and heated with a hairdryer. Under the influence of temperature, the glue becomes more liquid and impregnates the fiberboard to almost half the thickness. Once the glue has hardened, the resulting material is quite strong, essentially getinax, but on the one hand retains the sound-absorbing properties of fiberboard. You can cut DPV with a jigsaw, and you can glue the workpieces with epoxy glue reinforced with material. To do this, the blanks are folded into the desired structure and secured with any SUPERGLUE. Then strips of strong fabric are cut, in our case it is red silk. The width of the strips should be approximately 3...4 cm. The strips are laid at the joints of the workpieces, covered with epoxy on top, and then “ironed” with a 40...60 W soldering iron. High temperature allows the glue to completely saturate the fabric, and also significantly accelerates the polymerization of the glue. True, during operation a certain amount of smoke is released, so work must be done either outside or under a hood:
If the speaker power is higher than 10 W, but less than 20, then it is better to glue the fiberboard in half - first the sheets are glued together, and then the finished case is assembled:
For powers up to 30...35 W, you will need to fold the fiberboard in three or use 18 mm thick chipboard (unfortunately, 22 mm thick chipboard can only be found in old grannies in the form of old wardrobes made before the 80s). To stiffen the sidewalls, you can use spacers of the "CROSS" type:
For powers up to 50 W, the relevance of using fiberboard is already debatable - it is much easier to work with chipboard, MDF or plywood than to fold fiberboard from 4-5 layers. Material 18 mm thick is suitable for this, but you will have to use additional bars, providing a greater connection of speaker parts with each other:
The speaker can be assembled using self-tapping screws, but since the power is not greater, it can be glued with epoxy glue or PVA, but it is better to buy it not at an office supply store, but at a hardware or construction store. This PVA will be called MOMENT-STOLYAR, water-dispersion glue. Buy on the market Recommended only in summer - after freezing the glue seriously loses its quality. However, to ease your conscience, it is better to screw at least a couple of screws into each block.
When manufacturing speakers, sometimes they make a serious mistake - the mid-HF link is not acoustically protected in any way from the impact of the back side of the woofer cone, which leads to a decrease in the efficiency of the speaker itself, and often the failure of the midrange link - too strong air impacts from the back side of the woofer diffuser lead to the midrange speaker coil being pushed out of the magnetic gap and the coil jamming.
Much more often they forget to subtract the volume of the protective casing of the midrange-high-frequency speakers from the total volume of the speaker; as a result, the internal volume of the speaker is less than necessary and the final characteristics are greatly blurred - the resonant frequency of the phase interferors increases noticeably, which results in unwanted overtones.
When assembling speakers with a power of up to 100 W, you can also use either chipboard or plywood 18 mm thick, although of course it is better to look for material 22 mm thick. To eliminate the occurrence of resonances in the sidewalls of the speaker body, additional support bars are also used through which parts of the speaker are attached. There will be no superfluous installation“cross” and an additional washer for attaching the woofer dynamic head, as well as treating the speakers from the inside with sound-absorbing materials, for example, pasting with paralon or foam plastic 5-10 mm thick, just do not forget that the pasting will “eat up” part of the internal volume and it is necessary to give a correction when calculating the dimensions of the body.
Best results provides polyurethane foam, since the thickness of the applied layer can be adjusted by the speed of release of the foam from the can. If the foam is released VERY slowly, then it turns out to be very dense and the increase in volume is not very large. If the foam is released VERY quickly, then it turns out to be much looser, and when it hardens, it greatly increases in volume. If foam is applied to the sides of the case from the front panel, increasing the foam output as it approaches the rear wall, and ensuring a minimum rate of foam output at the front panel, the internal volume of the speaker will take the shape of a pyramid lying on its side. Such tricks make it possible to completely solve the problems of standing waves, since there are no parallel planes, and irregularities frozen foam only enhance the pyramid effect. When using this technology, you should be more careful when calculating the dimensions of the workpieces - the internal volume decreases VERY significantly and this requires a serious increase in the speaker body.
It is recommended to glue the ribs for fastening the sidewalls, in addition to the screed with self-tapping screws, as in the previous version, but there are several more options for adhesive masses:
- epoxy glue mixed with fine sawdust, or, better yet, wood dust;
- MOMENT-JOINER, but before screeding, the applied glue must be allowed to dry a little until the consistency is obtained butter room temperature. This will allow you to more completely fill with glue all the irregularities between the speaker parts;
- polyurethane glue, for example MOMENT-CRYSTAL, which also needs to be allowed to dry a little. After assembly, the gluing area must be thoroughly heated with a hairdryer, which will lead to the formation of small bubbles in the adhesive mass, and the mass itself will more tightly fill the unevenness between the contacting parts of the body;
- automotive sealant of domestic production, precisely domestic, since after hardening it is much tougher than imported sealants;
- mounting, polyurethane foam. Before applying it to the parts to be glued, the foam is “released” onto an unnecessary piece of plywood or fiberboard, and then thoroughly mixed with a metal spatula until it “shrinks,” i.e. until you obtain a mass similar in thickness to thick sour cream. After application and screeding, the foam will still expand slightly and completely fill all the irregularities at the point of contact between the speaker parts.
After gluing, the parts should be allowed to dry thoroughly for 20...26 hours.
To increase the volume at the same output power, you can use “double” dynamic heads - parallel or series connections of two identical speakers are used for the low-frequency section. In this case, the total area of the diffusers increases, therefore the speaker can interact with a much larger amount of air, i.e. create greater sound pressure and this makes the subjective loudness much higher:
It should be noted here that the use of a large number of speakers, including for dividing the audio range, begins to introduce some troubles - it is quite difficult to achieve signal phasing in those places where the frequency response of speakers neighboring in the range intersects. Therefore, you should not chase a large number of bands for a homemade speaker - this mess can be very spoiled with such oil.
It is better to make speakers with a power from 100 to 300 W from plywood, and you will have to look for plywood with a thickness of 22 mm. The speaker is also assembled using stiffening bars that are glued. It is better to give the bars the shape of equilateral triangles, where the legs will be attached to the sides, and the hypotenuse will be directed inside the body.
If you cannot find plywood of this thickness, then you can use 8 mm thick plywood glued in three - the final thickness of the material is 24...25 mm. The adhesives are listed above.
As technological advice, we can only recommend first cutting the necessary blanks and only then gluing them, and immediately tightening them with self-tapping screws.
When installing a “cross” inside the AC, which would not be amiss, it is better to round the corners of the tie bars - quite large volumes of air are already moving and turbulence may occur around the right corners of the screeds. It is also recommended to “round” all internal corners using plasticine or applying several layers of thick anti-gravel.
Another type of acoustic design is separate housings for each speaker. These speakers do not use passive filters, and the signal is divided into ranges immediately after the amplifier's volume control. The split signal is then fed to three separate power amplifiers, which each drive their own speakers:
It would be unfair not to mention the “fillers” often used in speakers - small rollers of sound-absorbing material lying inside the speaker. Such rollers make it possible to slightly increase the calculated internal volume of the body, however, in order to correctly manufacture such a “filler” it is necessary to know its acoustic properties. Obtaining the characteristics of the “filler” in a home-made environment is quite problematic, so the only thing left to do is either refuse to use the “filler” or experimentally find out the required volume and the material used (usually fluff wool, batting, sentipon).
At powers above 100 W, it also becomes important to ensure the stability of the speaker cabinet, since quite a lot of big job to move the diffuser and the air actively “resists”. It is also advisable to break the mechanical connection between the bottom of the speaker and the floor on which the speaker is installed. For these purposes, they usually use either tripods, which are problematic to make at home, or they use steel spikes screwed into the bottom of the speaker:
At powers above 200 W, it is desirable to strengthen the front panel of the speakers and it is desirable to use materials of different structures, for example, if the front panel is made of plywood, then it is glued on the inside chipboard sheet, the thickness of which is 1.5-2 times less than the thickness of the panel. This combination of materials ensures the absorption of vibrations in a larger audio range precisely due to the heterogeneity of the materials.
For greater stability of the speaker, its mass can be increased by coating the bottom with polyurethane polyurethane foam and lay a couple of bricks in it, covering them with the same foam on top. After the foam has hardened, it is better to cut off the irregularities with a stationery cutter. The “stolen” internal volume must be taken into account when calculating the size of the future speaker.
For powers above 200 W, it is better to use combination materials - all speaker parts are glued together from 18 mm chipboard and 18 mm plywood. Plywood is used as the outer layer and chipboard as the inner layer. This trick allows you to save a little - chipboard is much cheaper than plywood. It is advisable to glue the inside of the speaker with sound-absorbing material, for example, triple-sewn batting, double-stitched with quadruple padding (the padding can be double and quadruple), 5...10 mm polystyrene foam. The different structure of tightly glued materials of different structures eliminates the problem of resonance of the body itself.
It is better to additionally tighten the corners with metal corners - this will add rigidity to the structure and protect the corners of the speakers from damage - the speakers are already quite heavy and during transportation various impacts are possible from which the corners most often suffer.
For powers closer to 1000 W, the thickness of the material should already be quite large, for example, two layers of 18 mm plywood plus a layer of 18 mm DPS for a total of 54 mm, and the DPS is glued between the layers of plywood, however, the speakers already move into the category “for sound”, therefore quality can be sacrificed in favor of mobility. Based on this, you can use double 18 mm plywood, installing a “cross” inside.
It is not difficult to notice that with increasing power, the thickness of the speaker walls increases. This is primarily due to the fact that it is necessary to isolate the air moving inside the speaker from the listener. However, we should not forget that the speaker cabinet can also resonate. It is to eliminate this nuisance that it is better to use internal pasting of the housings and minimize the overtones resulting from resonance. It is not difficult to check the resonant frequency of the housing yourself. To do this, you need to tilt the speaker 20...25 degrees and throw a rubber mallet on top of it, from which you first pull out the handle. The tilt of the AC is necessary so that the blow is single and the mallet bounces far to the side.
A microphone attached to the speaker (the membrane hole to the body) and connected to any linear amplifier on the oscilloscope screen will draw both the moment of impact and the aftersound that the body itself gives. The test is, of course, quite crude, since in reality the “shock wave” comes from the inside, and during the experiment from the outside, however, based on the results of this test, one can judge at what frequency the body itself resonates and how quickly attenuation occurs:
An ideal speaker does not cut and the moment of impact fades immediately, almost instantly, but the walls of an ideal speaker consist of concrete 1 cm thick for every watt of power and such a speaker is more suitable for ridicule than for use:
The finishing of the speakers can be very different, there are no strict requirements here. If the body is made of plywood and the pattern is quite attractive, then the body can be sanded and then coated several times with colorless varnish:
You can buy veneer from valuable wood species and cover the speakers with veneer to match the color of the furniture in the room:
Car audio stores sell so-called acoustic fabric, which is synthetic felt. The material adheres well and stretches, which will allow you to finish the speakers at a fairly high level:
Having sanded the body, you can paint it with car paint, just make allowance for the fact that car enamels dry when high temperature. Therefore, you will have to use a special hardener "IZUR", the mixing proportions are written on the packaging of the hardener, although it is better to add 10-15% more than the suggested proportion:
If the body is carefully sanded and sanded, then it can be covered with a self-adhesive film sold in BOI stores, but this material is quite delicate and should be used if you are sure that the speakers will stand in their place for ten years:
If you plan to frequently transport the speaker system, it will be very useful to provide appropriate handles. This is especially true for small speakers, which you want to take two at once, and for large ones, which simply have a lot of weight.
How to independently assemble an active speaker with increased efficiency at low frequencies is described.
Site administration address:
DON'T FIND WHAT YOU WERE LOOKING FOR? GOOGLE:
Dedicated to those who have free time
We open a popular magazine about good sound and look with pleasure at the elegant images (if not the image) speaker systems, but there is something to see. Powerful towers bristle with speakers in all directions, shine with their varnished sides, crush the parquet with sharp spikes and generally evoke a feeling of deep respect. The only downside they seem to have is, of course, the price. A completely logical question arises: what if you make a copy of a monster yourself? Buying a speaker is not difficult, assembling the housing, even if it is not so beautiful, also, the coils and capacitors can be domestic, carefully soldering 3 parts is a task for a 10th grade school student.
Considering the number of ready-made modules that Ebay offers, making a good amplifier is not much more difficult. What’s not there: switching, speaker protection, A-AB-D class boards, volume controls for every taste, beautiful cases made specifically for audio, handles, legs and transformers - just know, connect. In the next article we will definitely tell you how to assemble your own amplifier, which will not be inferior to most “branded” samples costing up to 60-70 thousand rubles.
You may come across unfamiliar words later in the text. Fortunately, an unknown audiophile came to our aid and left link to your personal archive of information on acoustics and amplifiers, there really is ALL and even more, we strongly recommend that you read it.
What to make it from? Plywood, MDF, chipboard, plastic, solid wood.
The world has seen many strange acoustic structures, for example, made of concrete or cinder block. Still, the above-mentioned wood-based lumber remains the most “in demand”. Let's try to understand which one is “more correct”. Basic Rule– regardless of the material chosen, do not skimp on its quality, that is, price.
First comes the king of modern Hi-Fi and Hi-End industry - MDF, The vast majority of speakers, both expensive and cheap, are made from it. The reason is simple - low cost, ease of processing and finishing, including options with ready-made veneer, and the absence of bright resonances. With proper design, optimal results are guaranteed. We recommend it for use, nothing more to say.
Plastic - the concept is very loose, its “authority” is significantly undermined by cheap Chinese counterfeits, although it has no fewer advantages than any other material. We are passing by the problem of the inaccessible opportunity for an amateur to cast his own blanks from the desired material.
A good material for making an acoustic system enclosure can be Chipboard. Perhaps its main drawback is the many problems with finishing, no matter what you decide: paint, veneer or upholstery. Chipboard has a huge advantage: if you need to make it quickly and very cheaply, you can use factory laminated board(LDSP). In this case, it is unlikely that it will be possible to achieve high aesthetics, but the price and speed will leave all other contenders far behind. If we compare the resonant properties of materials in terms of suitability for speakers, chipboard takes first place, although the difference compared to MDF is small.
Capricious, but invariably desired by “seasoned audiophiles” madam plywood. There are several types of plywood - birch, coniferous, alder, laminated. Why capricious? Any plywood “leads”, that is, when the sheet dries, it changes its geometry, and chips often appear when sawing. It is also not the easiest material to finish if you want to get a “dull” matte color without visible edges, texture, or edges. The reason for enduring this torment is quite controversial: according to “experienced” people, only plywood gives that very living breath that chipboard and MDF “kill”. What I most incomprehensible is the desire to make a body out of “living” plywood and “kill” it with layers of putty, primer, paint, varnish in an attempt to hide the “terrible” joints with veins (layers of plywood), which look at their owner with silent reproach day and night . Options for special impregnation, at least with the same “Danish oil”, are much preferable; these dark “stripes” on the edges of the body are not so scary...
What kind of poverty is this chipboard-MDF? Maybe straight from solid oak, but thicker!? Don't rush to insert the speaker into the first hollow you see. Contrary to expectations array valuable wood does not enrich the sound in proportion to the money invested; moreover, it even requires additional damping compared to cheaper materials. Although its undoubted advantages are the ease of finishing: if the acoustics are assembled carefully, bringing it to a nice eco-look will not be difficult. Instead of increasing the thickness, it is recommended to add (glue) with reverse side another sheet of less resonant material, for example, the same MDF, to make a “sandwich”. Most good option applications of the array are “shield” type acoustics, where a beautiful and heavy front panel is required.
Exotic. Often the choice is determined by what is at hand. Just as a bird can masterfully weave all kinds of garbage into its nest, so a music lover drags everything that is in bad shape. You can find ideas on the Internet made from plumbing pipes, artificial stone, papier-mâché, cases and cases for musical instruments, primitive building materials, IKEA products, etc., etc.
Where should I put the speaker?
The main task of acoustic design can be formulated in simple language approximately like this: to maximally separate the vibrations emitted by the front side of the speaker cone from the same anti-phase vibrations emitted by the rear side of the cone. From the point of view of the textbook, the ideal acoustic design is considered to be an infinite screen, such an incredibly huge shield in which the speaker is installed. It’s clear that the words “incredibly huge” do not fit either our home or our salary, so engineers began to look for a way to “minimize” this screen negative consequences for sound. This is how all the variety of options turned out, some have gained the most widespread fame on the Internet, and we will consider them in this article.
Just a speaker or housing without housing
It’s hard to imagine that there is such a type of “acoustics”, but, scrolling through the feed of photos on Pinterest on the topic of audio, I increasingly come across clusters of 12-inch speakers that are assembled together without any design and clearly represent a complete unit. Probably, the author’s intention is permeated with the following logic: any housing spoils the sound, an acoustic one is better short circuit than wooden shackles, but in order to have at least some “lower”, you need to take speakers with the maximum diffuser area that you can afford. If this is your path - no comments.
Shield and “broadband”
They say that those who have tried the tube, full-range speaker and open design will never return to the traditional, transistor-rubber lifestyle. Describing the properties of a shield is not a rewarding task, all necessary information is in the archive, and for the laziest - on YouTube, where they explain in detail what kind of animal it is and what it is eaten with, for example: .
The biggest advantage of this design is its ease of manufacture. You need a sheet of your favorite material and a jigsaw. Most main criterion, which will affect the final sound quality - the cost of the installed dynamic head. The 4a32 speaker has gained unabated popular fame, even such grandees as fostex, sonido, supravox, sica or the visaton B200 itself are left far behind. The saying “size matters” is the best one mathematical formula for the shield (the more, the better). Next come variations of the shield, for example, a shield with folded side walls, a shield in which the low-frequency module is made in the form of a box with a bass reflex, etc. The signature feature of the sound is an “airy” sound with a minimum of resonances, and at the same time a relatively high sound pressure.
PAS – acoustic resistance panel
What if you try to cross a shield and a closed box? You will get a box with a back wall in which many holes are made. The number of holes, their total area in combination with the volume of the box will determine the degree of damping (resistance), the level of low frequencies (the fewer “holes” - the more bass, but also the more “mumbling”). The quantity is selected experimentally, according to taste.
Linear array of emitters, group emitter (GI)
In fact, this subtype of acoustics concerns more the speakers than the design of the cabinet itself. I think you've already seen columns, each of which consists of large quantity identical small-small speakers, or not very small ones, as your budget and living space allow.
According to the electrical diagram, the heads are connected in series, that is, the “plus” of the previous one is connected to the “minus” of the next one; it is possible to combine a series-parallel connection. The number of speakers, in fact, is also limited only by money; common sense, as a rule, by this moment disappears without a trace. Don’t think anything bad about me, I tried such a perversion, I even liked it, if possible, I strongly recommend collecting it for yourself similar design at least for the sake of interest. Again, the budget for this outrage is not very large; as a rule, domestic speakers in good condition are used, 5gdsh, 8gdsh, 4gd-8e, etc.
Acoustic design - the same shield or closed box, preferably of a tricky shape, for example triangular. One of the problems to be faced is the high total resistance; not every amplifier will reveal the potential of the “array”. Serial samples produced at the factory have more complex solutions, speakers are often assembled into clever modules, and filters are added.
Bass reflex, bass reflex port, Helmholtz resonator, aka a box with a “pipe”
Here it is - the most popular acoustic design option. The most favorable price/result ratio becomes widespread; our case is no exception to this rule. For those who haven’t downloaded the archive of an unknown audiophile, we’ll explain it in layman’s terms. There is a certain volume of air in the bass reflex pipe, which depends on its length; it is also “connected” with the air contained inside the speaker. With successful adjustment of the pipe length (let's not dive into theory right away), it is possible to achieve more confident reproduction of low frequencies than just in a closed box. To put it even simpler, with a bass reflex you get deep bass. For a more in-depth understanding, here is a video from a channel we already love:
Though this type acoustics and popular, it is far from being so easy to manufacture, one thing leads to another. Speakers that are suitable for this design are called “compression”, most often have a rubber surround and a frequency band that requires the installation of a high-frequency link, tweeter or tweeter, that is, an electrical filter is added. The choice of the optimal housing volume, its geometry, and precise adjustment of the pipe length are of great importance and do not always correspond to the calculated values. The situation is made easier by the presence of a mass of projects on the Internet, where the authors have already passed the thorny path and offer step-by-step instructions with detailed description what, how, from what should be made. However, there are always enthusiasts who are not satisfied with what is “ready-made” and have the tenacity to go their own way. The disadvantages of the bass reflex are “mumbling” and “crushed middle”. The first is solved by careful selection of the shape, diameter, material and length of the pipe; the second is by adding a separate mid-frequency section. The right path to three-way acoustics.
TQWP Reverse Horn and Other Labyrinths of Fate
What people haven’t come up with to complicate the path of vibrations coming from the back of the speaker... Perhaps the company that distinguished itself most of all was B&W with its Nautilus, at least erect a monument to this mutant sea shell. But these are grandees, and all we, ordinary audiophiles, can do is remember our nightmares and place boards with nails inside the rectangular box so that this vile sound doesn’t seem enough. Seriously though, there are speakers for which the “bass reflex” type design does not suit, and the shield does not provide the desired amount of bass, and the sight of the subwoofer makes something clench in your stomach. Then a reverse horn or a more complex option - a labyrinth - comes to the rescue. For those who are interested in how it works, we wish you pleasant viewing.
Someone may object: a reverse horn is not exactly a labyrinth, we can partly agree, but what is more reliable is that it is closer to labyrinths than a classic horn
reminiscent of an old gramophone. As you can guess from the name, a reverse horn or labyrinth is far from the simplest type of acoustic design; it requires a good understanding of the theory, accurate calculations, or at least compliance with factory recommendations. For example, large manufacturers of wideband speakers, as a rule, provide a couple of variants of housing drawings in the documentation for their speakers.
Onken, closed box (CB), horn, passive radiator and others
Our narrative follows in the footsteps of popular popularity, and this is a rather narrow list. A closed box almost always mumbles, it’s difficult to find a speaker for the onken, the horn is large in size, difficult to manufacture and calculate, the passive radiator works well, but for some reason it has not taken root in amateur designs. You can probably find several more rare types or subtypes of design that are not mentioned here, but what can you do, you can’t cover everything.
Damping, "stuffing", "plug"
The cases are ready, what to do with them next? That's right, damping. Damping can be divided into two types: vibration absorption and sound absorption. Well suited for vibration absorption automotive materials, mastics and special sheets with an adhesive layer, the latter is preferable. With sound absorption there is confusion and swaying, some people like felt, others like wool, batting, padding polyester, etc. The answer is quite simple - for different effects, depending on the type of housing and the frequency that you want to suppress, the choice of material will depend. Filling the case with sound-absorbing material increases its virtual volume, however, in my opinion, it is impossible to determine a universal norm.
Setting up a crossover (crossover filter)
You decided to make multi-band acoustics. Is a measuring microphone necessary? If this is a one-time project, then no, it is not necessary, it is enough to have a test selection of tracks and some experience to understand which sound can be called more correct. You’ll just have to go through the details of the passive filter longer, listen and compare, but in the end the result will be exactly what your ears and the room need. The situation is a little easier with active crossovers. Previously, you had to make them yourself, etching and routing boards, soldering, a very tedious process, especially if the circuit has a decent slope of cut and adjustment, for three-way acoustics it’s just a wild thing. Fortunately, today you just need to go to ebay and choose an option that suits your budget, whether you want it on op-amps or on DSP. You can smoothly adjust the frequency, and sometimes the slope of the cutoff (in especially rare cases, the phase), even every day.
The final
Sometimes it seems to me that the situation in the audio world is reminiscent of the legend of Tower of Babel. Once upon a time, in distant times, when Van Den Hul's foot had not yet set foot on the ground, people built together one set of home stereos. Large, large speakers, an equally large amplifier, and thick, thick cables stretched to them. Someone from above saw this and was horrified - what a joke, if only they had read some books... Severe punishment befell the unlucky audiophiles, since then they have been arguing until they are hoarse, but they still cannot agree on how to make amplifier speakers, so everyone makes their own , how can.
Do you have old unnecessary speakers or an acoustic system and you don’t know what you can do with them?
I’ll give you an idea for making an original portable audio system in a plywood case.
The design is quite simple and can be manufactured even by a schoolchild.
If desired, a bluetooth module, a charging module and a battery can be additionally installed, and then the acoustics become truly portable.
Materials and tools
Materials- plywood;
- modular amplifier tda2030;
- speakers from an old sound system;
- wood glue;
- power connector;
- switch with power indication (optional).
- jigsaw;
- clamps;
- drill;
- drills and crowns;
- soldering iron
Making speakers
The first step is to make the speaker housing.To do this, 7 blanks with a slot inside are cut out of plywood 15 mm thick.
You can cut the workpiece with an ordinary electric jigsaw.
After the blanks are ready, we begin gluing the body. Apply wood glue to the workpieces, press them tightly against each other and secure with clamps.
We also cut out the side front and back covers.
We drill holes for installing speakers and amplifier switches. Glue together with previously glued blanks.
We sand the workpieces by machine and by hand.
A ready-made tda2030 2x18 W + subwoofer module was used as an amplifier.
The speakers were taken from an old computer speaker system.
We prepare the back cover, connect it to the power socket, and also drill holes for RCA audio. We install the speakers into the housing, bring the module's knobs to the front panel, and install decorative covers.
Additionally, a small mini panel for the twisters was also prepared; we also cut it out of plywood and glued it using wood glue.
The body can be additionally treated with varnish or other impregnating and decorative compositions optional.
The plywood speakers are ready.
Additionally, you can display the power indicator with the on and off key on the front panel.
Although there are now many models of Bluetooth speakers on store shelves, any radio amateur is always ready to make his own portable Bluetooth speaker with his own hands and at the same time it will not be inferior in both quality and appearance to industrial ones, and the shape of the speaker can be chosen absolutely to suit every taste, surprising your friends with our creation, and the cost will be even cheaper than buying a ready-made one, since the parts and materials used are not expensive, in this article we will make a portable wireless Bluetooth speaker from plywood.
What you will need to create a Bluetooth speaker:
- 5 Watt speakers;
- Passive woofer;
- Ready-made inexpensive D-class amplifier module;
- Bluetooth module;
- Radiator;
- Charge module with battery protection;
- 18650 size battery;
- DC-DC boost converter 5V;
- 19 mm switch with built-in LED;
- Resistors 1 kOhm;
- LEDs 2mm;
- USB magnetic adapter;
- Charging at 5V 3A;
- Rubber sticker feet;
- Small screws M2.3 x 12 mm;
- Foam-based double-sided tape;
- Plywood;
- Glue gun;
- Epoxy adhesive;
- PVA glue;
- Sandpaper;
- Jigsaw;
- Drill;
- Forstner drills;
- Soldering iron.
How to make a Bluetooth speaker, step by step instructions:
So, I was originally going to cut out the front and back parts of the Bluetooth speaker housing with laser engraving, then I created a project on the computer that you can download (the names of the inputs and outputs will be engraved), but they can also be cut out manually with a jigsaw, although this is more difficult, but the result should also be turn out good.
The column uses only one material for the body - plywood, I used plywood from two different sizes thickness, for the front and back sides are 4 mm thick, and for the inside of the case, which consists of 3 layers - 12 mm. It is better to use plywood yourself best quality, so the fibers in it will be better processed and there will be fewer chips, flaws, and the Bluetooth speaker will ultimately look better.
The body consists of 3 layers of 12 mm plywood glued together. To do this, I took a ready-made front panel (you can take the back one), laid it on a sheet of plywood and traced it with a pencil 3 times to make 3 pieces. Then, using a jigsaw, I cut out three identical pieces along the contour (leaving a small gap for grinding). I strongly recommend using a plywood blade for a jigsaw, this way the edges of the plywood will be cut more efficiently, without unnecessary chips.
Now you need to sand each of the 3 parts with sandpaper, bringing the edges to the marking line. After this you need to draw internal lines departing from the edge about 6-10 mm, this will be enough to ensure that the body of the Bluetooth speaker is strong enough.
Next, I used a Forstner drill to drill holes in the corners near the frame outline. I did not drill all the way through, but to half the depth on each side of the plywood to avoid unnecessary chips. Then I took the jigsaw again and cut out the inside, moving along the contour from hole to hole. I did the same with the other two frames for the case.
After sanding the inside of the frames, it was time to glue them together. To do this, I applied a generous amount of glue to both sides of each of the pieces and pressed them together, aligning them and then waiting a few minutes to remove any excess glue that had leaked out. Then I glued the front panel to the body and clamped it with clamps between two sheets of plywood for an even gluing and let the glue dry.
After the glue has completely dried, we remove the clamps and can already see what our future wireless speaker looks like. Now I attached the back panel, aligned it, and pressed it with two clamps. I marked holes for small screws on the back wall and started drilling, I couldn’t drill them all at once, since the clamps were in the way, I drilled several holes and screwed the screws into them, and then, removing the clamps, I drilled the remaining holes. We tighten all the screws for the next operation.
When we have screwed the back panel in place, we begin sanding the back panel flush with the body and front panel. We use several types of grinding sandpaper, from largest to smallest.
When the body of the Bluetooth speaker is smooth, we drill holes in the top part for the switch with a forstner drill, I use a 20 mm diameter bit. Be sure to drill the hole away from the subwoofer passive speaker hole so that the switch does not interfere with that speaker once it is installed.
After sanding, remove the back cover. We cover the surface of the portable speaker body with varnish. I used matte clear nail polish from an aerosol can and was amazed by the result, the body looks amazing.
We install the wideband speakers at the edges and the passive low-frequency speaker in the center, attach them with hot glue from a glue gun, before soldering the wires to the speakers.
According to this diagram, we solder together all the modules, connectors and LEDs with wires:
I soldered two 1K resistors for the right and left channels of the amplifier to turn the stereo signal into mono, since we will be connecting speakers in the same cabinet, so the signal should be the same for both speakers.
I soldered the SMD LEDs on the battery charging board and soldered the wiring for the external LEDs instead. I did the same on the Bluetooth module.
On the back wall we see a list of all the connectors and places for the LEDs of the Bluetooth module, we place all the connectors and LEDs on the back panel and glue them with hot glue, and in the same way we attach the modules to the back wall. We also glue the battery with hot glue to the bottom of the Bluetooth speaker. To fix the modules, you can also use double-sided foam-based tape; it holds such components well in place and you can additionally add hot-melt adhesive on the sides. Make sure that no wires touch the woofer, otherwise it will produce an unpleasant rattling sound when playing music.
Once all the components are in place, before screwing the back panel of the portable speaker in place, I glue a thin foam rubber strip along the side of the back wall case to make the speaker case as airtight as possible and now we can screw the back panel into place. Be sure to tighten the screws well so that the foam strip is pressed down well.
Plywood is considered one of the leading materials in the production of acoustic systems. The popularity of this lumber is due to the fact that its use guarantees sound-reproducing equipment:
- high sound quality;
- lightness and aesthetics;
- strength and durability;
- resistance to factors environment;
- Possibility of installation in any type of premises.
The plate is suitable for the manufacture of both professional and household sound-reproducing equipment.
In the production of speakers, multi-layer or more is used, in the creation of which birch veneer is used, which differs smooth surface. Front side the slabs are subjected additional processing: After sanding, it is varnished or laminated.
Due to the possibility of coating and the natural texture of lumber, acoustic equipment made using plywood can be an addition to any interior.
Such speakers, if necessary, can be easily mounted in walls or acoustic shelves using special fasteners, without the risk of damage, delamination or crumbling of the material.
The use of a stove increases the cost of equipment, but these expenses are completely justified. After all, professionals and lovers of high-quality sound have long appreciated plywood products and their acoustic capabilities.
Acoustics made of high quality plywood
In addition to plywood, plastic, metal, solid wood, chipboard, and MDF are used to make speakers. However, as a result of testing carried out by the world's largest speaker manufacturers, optimal material Birch plywood has been recognized for the production of high-quality sound-reproducing equipment. The remaining samples of structural materials showed lower indicators of sound quality, reliability and wear resistance.
The use of this lumber improves the quality of the acoustic system and gives it the following advantages:
- Absorption of vibration wave.
- High level isolation.
- Resonance smoothing.
- Clean playback.
- Directionality of acoustic energy.
To create a series of budget equipment, manufacturers make a compromise and combine two types of materials: they make a case from a 16mm thick fiberboard sheet with a lining made of, which helps to reduce and sometimes completely eliminate resonance.
It is important to know: in order to obtain acoustic equipment with a high-quality plywood body, it is worth taking into account the specific features of the use of this lumber. So, when making a body, it is worth dividing the box with stiffening partitions and gluing its inner surface with a material that absorbs noise and vibration. This allows us to provide excellent clarity of sound and offer the buyer high-quality acoustics at an affordable price.