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, excess air pressure is formed on one side, and the air is discharged on the other. For sound to occur, it is necessary that air vibrations propagate into space and reach the listener, and 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.
The main options for acoustic rupture short circuit some. 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 slightly more complex method is an 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 is paid to the tightness of the box - any gap in the box will produce overtones, since both a sufficiently large pressure arises in the box (when the diffuser goes inside the box) and a fairly large vacuum (when the diffuser moves outward):
The next option for acoustic design is a box with a bass reflex:
In this case, this is a 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.
More difficult option acoustic design - 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. Towards calculation and manufacturing accuracy similar 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 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 the AS, some should be taken into account technological features- if the front panel on which the speaker is installed is recessed into the housing, then it will be necessary 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 you can get flat surface quite difficult. 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 speakers of medium and high price categories, 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. For this, material with a thickness of 18 mm is suitable, but you will have to use additional bars to ensure a greater connection between the speaker parts:
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. It would not be superfluous to install a “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” part of the internal volume and it is necessary to make an adjustment for it 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 inside the speakers, and the unevenness of the frozen foam only enhances 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 it reaches the consistency of butter at 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 work is already being done to move the diffuser and the air is actively “resisting”. 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 foam and laying a couple of bricks in it, covering them on top with the same foam. 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 inside the speaker 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 obtained 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 valuable species trees and cover the AC 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 described.
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A speaker is an acoustic system of very modest size, containing one or more loudspeakers with a built-in amplifier. Speakers are used to increase the volume of sound, and the sound is amplified by speakers. Speakers consist of two magnets: usually a ceramic permanent magnet and an electric magnet, which is controlled by an audio amplifier. Thanks to these magnets, sound is produced when they interact. Speakers are divided into two more categories: passive - that is, in which there is no built-in audio amplifier, for example, headphones; and active - respectively, speakers that have their own built-in audio amplifier. The active speaker system has its own power supply. In this article you will see how to make a homemade active speaker system with your own hands. This speaker can be connected to a computer, a phone, a player, and so on. To make this homemade product I needed:
Materials:
1) Two speakers with a power of 3 watts each (they will serve as a sound source);
2) Three and a half millimeter plug for connecting the speaker to different devices;
3) (the amplifier will receive sound signals from some device and transmit them to the speakers, amplifying these signals);
4) Switch to turn off the speaker power;
5) Wires for connecting contacts;
6) Insulating tape for insulating wires and other needs;
7) USB plug for connecting to power;
8) Heat-shrinkable tubes for insulating exposed contacts;
9) Plywood (the body will be made from plywood, since this is the most affordable material);
10) Self-tapping screws for assembling the housing.
Tools:
1) Electric soldering iron for soldering wires;
2) Glue gun and hot melt adhesive for gluing some parts and for insulating contacts;
3) Stationery knife for cleaning wires from insulation and for other needs;
4) Lighter for heat shrink tubes;
5) Hacksaw for sawing plywood;
6) A jigsaw for cutting round and other holes on plywood;
7) Electric drill for drilling holes;
8) Screwdriver for tightening screws;
9) Ruler and pencil for drawing marks on plywood for the speaker body;
10) Sandpaper for sanding the body;
11) Wire cutters for cutting wires and unnecessary contacts;
12) Compass for drawing circles.
The process of making a homemade active speaker.
Let's prepare two three-watt loudspeakers, a 3.5 mm jack and a PAM 8403 audio amplifier and connect their contacts using connecting wires.
The characteristics of the speakers are written down on the back side, and here they are:
The 3.5 mm connector has three contacts: left channel, right channel and common. There are also four contact plugs: left and right channels, general and microphone; but this speaker doesn’t have a microphone, and why would it, so you don’t have to use a four-pin plug. The values of the plug contacts are shown in the photograph.
We will use an audio amplifier ordered from AliExpress of very good quality, as mentioned earlier. This amplifier is powered by a voltage of five volts, so the future speaker can be connected to both a laptop and a phone charger...
We will also use the power button to turn off the speaker.
We take the wires and strip their ends of insulation using a craft pressure for future soldering.
We solder these wires to the audio amplifier using an electric soldering iron, but very carefully so as not to spoil or damage the amplifier.
In my case, the blue wire is positive and the brown wire is negative.
We cut off the excess protruding contacts using wire cutters to make it look neater.
We secure the wires together using insulating tape.
It should look like this, as shown in the photo.
Now we solder the power wire to the amplifier with a USB plug. Yes, there will be a wire at the end of the article white, since I resoldered it due to insufficient length, so don’t judge too much.
We strip the USB wires and solder one of the wires using an electric soldering iron to the speaker power switch.
We insulate the wiring using heat shrink.
Now we solder the resulting two wires to the audio amplifier, being sure to observe the polarity: in my case, brown is minus, blue is plus.
Again we bite off the excess on the board with wire cutters.
Here's what I got:
Now we solder a wire with a 3.5 mm plug to the audio amplifier.
The wire must have at least three contacts, but exactly three is better.
We strip the wires and solder them to a 3.5 mm plug.
Now we solder the wires to the audio amplifier, but each wire is in its own place.
According to the colors of the wire, we solder them to the board, namely the black wire is the left channel, which is marked on the board with the letter L; the red wire is the right channel, which is marked on the amplifier with the Latin letter R; and the green wire is the common channel, which is marked on the amplifier accordingly with the Latin letter G.
Now we insulate the 3.5 mm plug with heat shrink and hot glue.
In general, I got it like in the photo.
Now it starts over difficult process, namely the body blank.
Drawing a rectangle on plywood, when dividing it in half we get two identical squares, in each of which, in the center of the squares, using a compass, we draw circles of equal diameter for future seats speakers.
By using electric drill drill a hole to thread the jigsaw into this hole.
Cut out a rectangle using a hacksaw.
Using a hand jigsaw, cut circles from the rectangular part of the speaker housing.
Three-watt speakers can be easily inserted into the resulting two holes.
And two more rectangular parts of the same size.
For now, we are assembling the body from everything received.
Now you need to attach the audio amplifier to the front of the case.
To do this, we drill a hole using an electric drill, so that the amplifier can be installed freely and securely in this hole.
From the inside of the part near the drilled hole, using a utility knife, we dig out a recess for the amplifier board.
At first glance, making your own speakers is quite simple. However, this is misleading. First of all, it should be noted that the models are manufactured with various elements. Depending on them, the device parameters and sound quality will be different.
There are special requirements for computer speakers. You can also make a model for your car or studio yourself. In this case, it is very important to follow the instructions. First of all, for assembling speakers you should consider standard scheme models.
Speaker layout
The speaker circuit includes drivers, pads, diffuser and crossover. Powerful models use a special bass reflex. Amplifiers can be installed with field-effect or switching transistors. To improve sound quality, capacitors are used. The woofer is matched with the amplifier. The dynamic head must be attached to the seal.
Single speaker models
Single speaker speakers are very common. To assemble the model, you will first have to deal with the body. Plywood is often used for this purpose. At the end of the work it will have to be sheathed. However, the first step is to make the side posts. For this purpose you will have to use a jigsaw. you can choose a small power.
The inside of the plywood is necessarily stitched with vibration-proof tape. After fixing the speaker, the seal is fixed. Glue is used for this purpose. Next, all that remains is to attach the diffuser. Some people make a separate shelf for it and fix it with stacking screws. To connect the speaker to the plug, a terminal block is installed. How to turn on speakers? For this purpose, a cable is used from the terminal block, which should lead to a power source.
Model drawing for two speakers
Speakers with two speakers can be made for home or car. If we consider the first option, then a pulse type diffuser will be required. First of all, durable plywood is selected for assembly. The next step is to cut out the bottom post. Models with legs are very rare. To cover the veneer, you can use regular varnish. There is no need to glue vibration isolation tape to the front pillar. The diffuser is mounted under the speaker. To make a hole in the panel, you need to use a jigsaw. The bass reflex is fixed at the rear wall. Some manufacture devices with horizontal speakers. In this case, the diffuser will be located at the top of the structure. Speaker wires are of the two-core type.
Devices with three speakers
Speakers (homemade) with three speakers are very rare. These devices are most suitable for the multi-channel type. To assemble the model, first of all, sheets of plywood are selected. Some also recommend using veneers. However, models from natural wood They are quite expensive on the market. The speakers should be installed horizontally. The device will also require an amplifier.
To fix it, use metal corners. To connect the plates you will need tightening screws. In some cases, the plates are secured with glue. Next, the model will have to be partially covered with leatherette. The next step The terminal block is installed. In order to fix it on the body, you will need to make a separate hole. It is also important to note with regulators. Microcircuits for them are used of the capacitor type. When the speakers produce noise, you need to change the diffuser.
Studio devices
Speaker drawings for studios assume the use of powerful speakers. The diffuser is most often used of the pulse type. Many experts recommend installing two amplifiers. For normal operation you will need a zener diode.
In order to assemble the speakers yourself, the housing is first made. On the front panel for the speakers are made round holes. You will also need a separate output for the bass reflex. The design of the columns is quite different. Some people prefer to varnish the surface of the case. However, there are models covered in leather.
Models for computers
Speakers for computers are often made with one speaker. To assemble the model, veneer sheets of small thickness are selected. A hole for the speaker is cut out on the front panel. The bass reflex must be located at the rear of the housing. If we consider low-power models, the amplifier can be used without a resistor.
To adjust the speaker volume, special crossovers are used. These elements are allowed to be installed on a bass reflex. If we consider devices with a power of more than 100 W, then amplifiers can only be used with resistors. Some people select pulse diffusers for the model. At the end of the work, the terminal block is always installed.
Automotive modifications
Available with two or three speakers. To assemble the model yourself, you will need sheets of plywood. In some cases, varnished veneer is used. To fix the speaker, you need to make a hole in the panel. The next step is to install the bass reflex. Some modifications are made with low-frequency cores. If we consider speakers (homemade) of low power, then the bass reflex can be installed without an amplifier.
In this case, a multi-channel crossover is used to control sound. Some specialists install terminal blocks behind the bass reflex. If we consider speakers with a power of more than 50 W, then the microcircuits are used for two amplifiers. The diffuser is installed as a standard pulse type. Before fastening the case together, it is important to take care of the vibration-proofing layer. For the terminal block, you need to make a separate hole on the plate. Some people believe that the body must be cleaned. The wires for the speakers are of the two-wire type.
Open-back speakers
Portable speakers with an open case are quite easy to make. Most often they are made with one speaker. Holes are made on the back panel of the device with a drill. The plates are directly connected with tightening screws. The diffuser for such devices is suitable for pulse type. Bass reflex units are often installed with one amplifier. If we consider powerful portable speakers, they use a resistor crossover. It is attached to the bass reflex. Many experts recommend installing speakers on a seal.
Devices with closed housing
Speakers (homemade) with a closed housing are considered the most common. Many experts believe that they are the best in sound quality. Bass reflex devices for devices are suitable for the operational type. The woofers are installed in the holes. For the purpose of assembling the case, ordinary sheets of plywood are suitable. It is also important to note that there are modifications with cores. If we consider high-power speakers, the terminal blocks are installed in the lower part of the housing. The design of the models is quite different.
20 W models
Assembling 20V speakers is quite simple. First of all, experts recommend preparing six sheets of veneer. They should be varnished at the end of the work. It makes more sense to start assembly by installing the speakers. The bass reflex is used as a pulse type. In some cases it is installed on pads. Experts also recommend using rubber seals.
Power supply to the speakers is provided through the terminal block. It is attached to the back panel. The bass reflex can be installed either with or without an amplifier. If we consider the first option, then the cores are selected of the phase type. In this case, the woofer does not need to be used. If we consider speakers without an amplifier, then they use a crossover. At the end of the work, it is important to clean the body and varnish it.
50 W devices
Speakers (homemade) rated at 50 W are suitable for ordinary acoustic players. In this case, the body can be made from ordinary plywood. Many experts also recommend using natural wood veneer. However, it is important to note that he is afraid of high humidity.
After choosing the material, you should work on the speakers. They must be installed next to the bass reflex. In this case, you cannot do without an amplifier. Many experts recommend selecting only low-frequency crossovers. If we consider modifications with a regulator, then they use a pulse diffuser. The terminal block in this case is installed in last resort. You can always use leatherette to decorate the speakers. More simple option is considered to be coating the surface with varnish.
Speakers with a power of 100 W
100 W speakers are suitable for powerful ones. In this case, the bass reflex is taken only of the pulse type. It is also important to note that the amplifier is installed with a crossover. Many experts recommend using veneer to assemble the case. It is better to install the woofer on a pad.
Today I will tell you, dear Durkovites, how with my own hands to do something that costs a lot of money in the store. That is, a good speaker system. I remember once posting here about the S-30, and from that moment I started making my own speaker like this from scratch.
Let me start with the fact that when I found this pair of S-30s in a barn at the dacha, I was almost stupefied - not only are they different (one is s-30B, the other is S-30A), but one of them also has a broken body. The second one did not have a filter inside; someone had already removed it before me. There was no point in doing restyling - they are too different, and I didn’t know how to restore the half-rotten body. And why, when you can remake 2 identical ones. The woofers, GDN-25, are in perfect condition, but it’s better to install new tweeters. Well, let's begin.
Part one. Columns. 
I didn’t think about the material for a long time - the walls were from some kind of Soviet sideboard (16 mm chipboard), and with holes. We fill the holes with pva dowels. Next we cut to size. Oh yes, the most important thing is the size. I took approximately the same dimensions as the original S-30, only slightly changed the shape. But the bass reflex had to be calculated in SpeakerShop. I took it with a margin of 50 mm. We twist the body with self-tapping screws, this is still a fitting. 
We disassemble, apply glue, and assemble. We glue glazing beads into the corners for added strength: 
Now we dampen everything with linoleum, the furry side inward: 
We collect completely. 
Now that everything is working for us and there is no whistling anywhere, we can putty. 
Well, now the most tedious and dusty part - sanding... 
After a couple of hours, you get something smooth and velvety. Can be pasted over. At first I wanted a black wood-look self-adhesive, but in our, sorry, muhosransk there wasn’t one. But how nice it is to have friends in other cities! In a month I will of course have it, but for now I’ll have to cover it with what I have. something like this: 
In order not to mess around with the style of the front panel, we make a black acoustic grill. (It’s better to make it from acoustic fabric, but if your budget is tight, you can get by with women’s black tights; you can’t tell them apart by appearance. The most important thing is to ask your girlfriend/friend/mother for permission to take these same tights. Sometimes they cost many times more than the acoustic fabric itself , so be careful ;)) 
It turns out no worse than purchased ones, it seems to me: 
While I was making the amplifier (more on that later), they brought me some self-adhesive tape. My joy knew no bounds! 
And now the most important thing - don’t skimp on connectors! I first bought Chinese ones for 15 rubles, and was very disappointed. They make very unpleasant sounds at low frequencies, so don’t do anything with them. Therefore, I bought some branded ones, with gold-plated contacts. Believe me, this greatly affects the sound. The extra 300 rubles are worth it. 
Now we install the tweeter. I bought car speakers, I couldn’t find normal ones from us, I picked out the speakers themselves from the case, and placed them in a hollowed-out recess using PVA-based putty. 
Well, and most importantly, because... I had to remove the domes on the woofers due to their rattling, so I made new ones with my initials :) 
Needless to say, the sound turned out to be no worse than branded speakers of famous audiophile trends. 
Part two. Amplifier.
The speakers turned out just like the original, 30 watts each - 25 watts LF and 5 watts HF (although according to the documents it is written that these tweeters are 60 watts each, but it’s more expensive for the Chinese to believe themselves. The sound is no more than 5 watts) At first I had an amplifier - I assembled a year ago from an AT power supply and a TDA1558Q mikruhi. But firstly, there are only 44 watts, and secondly, this mikruha pulls out the bass rather weakly. I didn’t think about choosing a microcircuit for a long time - TDA 8560Q. Similar to the previous one, only the output is up to 80 W, + the signal quality is higher and there is less distortion. I immediately warn beginners - it’s better not to assemble anything on the 8560, it’s very capricious. But if your hands grow from the right place, you will get a wonderful amplifier. While assembling mine, I burned two of them. And they cost about 150 rubles apiece, which is money I feel sorry for, so I have honed my stock of obscene language well. The case will be made of one-sided foil fiberglass. Convenient, lightweight, and does not conduct current where it is not needed. It is also a wonderful mass, screen and antenna (if you connect a phone with a radio receiver) 
We mark, cut with a jigsaw, drill the necessary holes:
I couldn’t resist and tried on future connectors :) 
We sand the solder joints and tin. 
We heat the tinned areas with a soldering iron and everything sets wonderfully: 
Now we putty all the cracks and joints with auto putty. A day later we safely sand and polish. 
Let's try the filling: 
Everything works, you can paint it. We paint it with glossy black paint, after which we sand down the defects. 
And now the main highlight is the aluminum inserts. A parody of expensive amplifiers, it’s like protective steel corners. We cut it out of a 3mm sheet of luminium, bend it to the shape of the front panel, add a texture with sandpaper, and screw it in with hex bolts (that’s bolts, this is also part of the design). Looks Cute: 
We remove all the props and take out the filling. We paint normally: 
The result is this small wonderful case:
Now about the filling. Microwave Tda8560 on a radiator from a 300th celeron, a transformer (which is at least 40 years old, but produces about 15A and 12V), diode bridge approximately 12A and 3 capacitors: 4700 µF, 2200 µF and 0.47 µF connected in parallel. Two condensers at the signal inputs of the mikruhi, 0.05 microfarads each (also Soviet, much better than the Chinese ones), and an input dual variable resistor of 50 kOhm. Cooler (left over from the computer power supply, at first it was this one) 2 and blue LEDs from below. That’s the whole circuit . 
And so that the 2-kilogram transformer does not warp the body, we strengthen it with two corners and a steel plate at the base, on which everything is actually attached. 
Now we make the bottom from the same PCB and the legs from a nickel-plated furniture tube:
Looks good next to my system unit, the same blue backlight (in the photo, unfortunately, the computer is turned off): 
Part three. The final.
Now everything is assembled and works great. In total it took me about three months. And I’ll say right away that here are only a third of the photographs, the rest show what went wrong with me, after all, this is my first project with such precision and such high-quality elaboration of every detail.
P.S. I’m in 10th grade, and this is supposedly my project for the regional technology Olympiad, at which, by the way, I took first place 3 days ago.
Happy modding! Sincerely yours, Viktor Sarbaev.
I dedicate this material to all do-it-yourselfers and wish them good luck in their work.
Start
Dear friends, allow me to introduce myself. My name is Yuri. He received his name in honor of Yuri Alekseevich Gagarin, like many boys during that period. It was so popular when I was born. Apparently, the energy of that time and the name of the first cosmonaut was, to some extent, passed on to me and became part of the soul, requiring activity. During school years, activity was multidirectional, but did not include studies. This did not become a hindrance in life. Graduated from Technical University with honors. I did not change my profession, chosen on the basis of the maximum complexity of the specialties offered by the university I entered, and I still earn money from it. They taught me to be a designer hydraulic machines and means of their automation.
In his free time from work, all sorts of hobbies continued. In another emotional outburst, which happened quite recently, I discovered a wonderful Audiomania store, in particular, its “Do it yourself” section. What I saw there on my first visit was a youthful dream. True, in those days it was impossible to imagine such a thing. The assortment of this store opened the door for me to the world of realizing ideas. I think, like for many other people obsessed with ideas.
In addition to my passion for audio technology, which accompanies me throughout life, I love photography, read science fiction (definitely about space travel - that same energy works out). And one more hobby - I have been making wooden furniture for almost a dozen years. Nowadays we already have serious experience as a cabinetmaker, which allows us to make furniture professionally.
Creating acoustics, which will be discussed, is one of my long-time hobbies. But the accumulated experience, today's opportunities and new desires have allowed us to set ourselves a difficult task - to create acoustics for the home that convey the dynamics, scale and emotionality of concert music performance.
To all readers - my immense affection and best wishes.
Yuri Kobzar
I'm an amateur. I will try to write only about specifics. I will share my practical experience in creating acoustic systems high level. I address this information to fellow fans who like high-quality sound, who get pleasure not from the background, but from listening to music. People who are in the world of sounds have preferences and favorite records.
In the spring of 2017, something happened to me. In the evening, on the veranda, the chirping of birds reached my ears, a real warmth wafted through, somewhere turned green, the first one flew vegetable aroma, I wanted to sip some wine and listen to music. Without analyzing (everything can be attributed to fluctuations of the soul), I felt the need, and I had the idea to acquire good sound for the home. Moreover, there is “music” in the house. But at that moment the term good sound suddenly took on a different meaning. Memories of randomly listening to music in a store (in the high-end room), a great opportunity to experience the highest quality sound from several friends, came into my head. All this happened years ago, but the need for good sound took shape in the spring of '17. Despite the fact that a reverent attitude towards “good” music has accompanied me all my life, and I almost always had the opportunity to listen to sound of decent quality, it suddenly became clear: the music sounding from acoustics should not just be clean, detailed, powerful, deep, natural, bewitching or even amazing (body at high volume is a joke). The sound reproduced by acoustics must convey the emotions of the soloists and musicians, and all those who prepare the recording for us, the listeners.
According to preliminary estimates, possibly overestimated, it turned out to be unaffordable to buy such equipment. I didn’t want to waste money on something good that was available. Thus, the task arose to build the highest class acoustics available at home. Without laboratories, high-precision measurements, but so that the breed, solidity and eliteness of the sound is undeniable. To create just such an impression from listening.
As a small digression, it should be said that the idea had a basis. I had certain skills at my disposal: in my youth I built acoustics in a “closed box”. I was happy with the sound of it. Various transistor amplifiers were soldered together, one model is extremely high quality. Now, in addition to the previous half-forgotten knowledge, skills and experience, I have added a love for making furniture from wood and a certain set of carpentry tools. Additionally, I wanted to acquire a high-quality tube amplifier. In order to shorten the implementation of the plan, I offered participation to my enthusiastic friend and homemade worker, who has the base of the radio department of UPI (Ural State Technical University). It was agreed that acoustics (selections, calculations and implementation) would be my task, and the lampmaker would be part of it.
From this position they began to “shake the old days.”
Choice
The issue of building an AS began with the study of theory and related materials. I, like many builders of their own acoustic systems, faced the question of choosing an acoustic design. Knowledge, information, opinions began to accumulate and be systematized, but the answer to the question about the type of acoustic design of the speakers remained open. At this time, three 75GDSh3-1 broadband heads became available to my partner. The local cultural center decided to throw away two stage subwoofers that had worked for more than 30 years. Each had two speakers. In one of them, the speaker failed, hence the decision to throw it away. Listening to the speakers "on the floor" confirmed the expectation of "no sound". Listening in the original subwoofer box did not change the ratings. Almost without enthusiasm, I began to dig through the Internet on the topic of using speakers of the existing type in speakers. Materials from comrades who had already built speakers based on these speakers were quickly found. I liked the option with “tekuvete” (tqwt) Voight pipe - I am attaching the material, the authorship has not been established, see link). I liked this option, among other things, because of the “open body”, for which some people already liked it. Why: No or minimal speaker damping as needed. In other words, there are no obstacles created for the dynamic head during operation, and this, as I understand it, means a minimum of conditions for creating external resistance and, as a result, distortion. Also, the resonant frequency of the speaker in the housing with the pipe does not change. This, in turn, should ensure the reproduction of a richer bass component, which is the basis of the rhythm, providing volumetric sound and enhancing the psycho-emotional perception of the musical program. With internal resistance (after listening to the speakers), with the fear of getting a weak result and, nevertheless, with hope, I bought three sheets of 12mm construction plywood to replicate the proposed design in the material. The modification consisted of using radial transitions in each corner (for the first time I bent plywood), installing a stiffening rib inside (taking into account the dimensions and thickness of the material) and installing a rigid removable rear wall for the convenience of subsequent possible damping.
I don’t give the manufacturing technology. Open it too. Considering my experience in working with wood, I believe that each craftsman who undertakes the manufacture of such a structure will have his own specific design and manufacturing work. The specifics are related to the conditions, skills and set of tools. I got used to working with glue, refusing metal fasteners (except for the removable back wall). This ensures the absence of technological racks that take away volume, giving additional geometry in the sound channel, which from my point of view - a certified hydraulics specialist - is not good for the movement of a sound wave along the channel. And the task, by the way, is to create conditions for its smooth, laminar (there is a term meaning the absence of turbulence) movement along the channel. This reduces the likelihood of overtones that are unnecessary for high-quality sound.
The sound of the built speaker surprised me right away. Powerful, bright, beautiful and different from my signature three-way bass reflex (FI) speakers of the English brand. Significantly excellent. With emphasis on the word “excellent”. The surprise was intensified by the fact that there was England, the intelligence of engineers and large-scale production, and here was a 35-year-old miracle in a plywood box. After the first surge of emotions subsided, it became clear that one speaker was not enough for this speaker. There are not enough tops and... bottoms. The bass is low, beautiful, with many shades (which is not heard on the FI) and, at the same time, weak. You can talk yourself into such a sound, but the drawback is noticeable.
Having doubts about the ability of this speaker to play bass in a wideband speaker system, I built a tapering labyrinth - a transmission wave line (TVL). According to reviews online, this is exactly what is needed. I describe without details or arguments in favor of such a decision. I do not provide recommendations and dependencies for constructing TVL. Everything is on the Internet. I made this design more technologically advanced: with legs, without roundings. It should be noted that the speaker turned out to be more compact in size. Here's her cut.
Many authors on the network mention the importance of correctly made calculations of the transmission-wave channel, the absence of fundamental errors, the complexity of the design and the need to accurately repeat it during manufacturing. At the same time, apart from geometry and rules for choosing speakers, there is actually nothing in their approach. When drawing the design of speakers with TVL, I was accompanied by a feeling of deep understanding of mechanics, but not acoustics. I did everything on faith. After all, many people have already shared practical experience, achieved results and photographs. Many were satisfied with the resulting sound. This is a weighty argument.
I took construction plywood again. This time, two sheets, taking into account the remains from the previous version. Made it quickly and accurately. It should be emphasized that the bodies of such structures are excessively rigid, even when using 12mm plywood.
So, the listening experience is very good. The disadvantages are the same. If the lack of highs is a speaker design, then the lack of bass is a matter of the cabinet. It should be said that the bass has become more expressive and emphasized. This was noted independently by all audition participants. The surprise was as follows. At first, we listened to each speaker separately. I wanted to hear its capabilities and compare it with another option. Moreover, the first experiment of repeating the design yielded only one column. Then they were connected together. The effect was amazing. Not only a panorama of sound, a stage emerged. First of all, the sound itself has changed. Its power, openness, and lightness stunned me! Yes, later, while listening to an unequal pair of speakers, I had to raise the HF and LF on the amplifier. But the sound was not just beautiful. He held, pulled to himself. My favorite tracks sounded as if I was listening to them for the first time. On many, shades of bass and mid frequencies began to be heard, the existence of which I had not even suspected before with English floorstanding speakers. A friend of the wife who is present with her in the house in next room While testing a pair of speakers at different volumes and styles: chamber music, jazz, electronics, when leaving, she said that she had been to a philharmonic society or a concert. This phrase was not delicacy towards the owners, but similar to the truth. The propagation of sound across adjacent rooms was a pleasant surprise. This will be an important point when receiving guests to create a light, unobtrusive musical accompaniment in several zones at once. He started turning on the equipment every time he passed by. And, in the end, after three days, he finally gave up and asked the future owner to take this test version of the acoustics home to listen to until the time came for the production of ceremonial-looking speakers.
The conclusion was this: if I had chosen the speakers in the store, the sound of the resulting speakers (not the plywood look, of course) would have suited me completely. The resulting sound is said modestly. The sound is great. When a pair of speakers are playing, the high frequencies are almost enough. This is not sand, the speaker cannot reproduce it. But what it reproduces already satisfied our requirements. The resulting sound was shocking, turning something inside me, causing lumps in my throat. No exaggeration. There was only one “thorn” left - the bass on the amplifier was turned up to maximum. However, the owner of the speaker also liked the sound. Later it was even decided final version made on the basis of TVL: dimensions and bass sound prevailed.
ordeals
Meanwhile, the issue of creating speakers for “own use” has become urgent. There is a high probability that after the speakers on the 75GDSh3-1 speakers, the search for good sound would have come to an end. It happened quite quickly, and it almost hit the mark. Fortunately or unfortunately, there was no second pair of 75GDSh3-1 or 3-3 heads. While crawling on the World Wide Web, collecting and analyzing information, continuing my studies, I began to closely examine the acoustics of the English company Tannoy. An ideal speaker is a device capable of linearly reproducing the entire spectrum of sound from one point. And life consists of compromises. Creating acoustics is a search for the optimum among many compromises. Each version of the speaker solves its own problems and becomes a tool in the hands of marketing: good combination speakers in an acoustic system, beautiful (correct) frequency separation, protruding bass, clicking tweeter, unique design, the use of precious wood in the case, or simply a well-known brand. All together or separately is designed to convince the buyer of the correct choice. The older Tannoy acoustics (Westminster and Canterbury) interested me in appearance, and they are built on just one speaker. Sound from one point! The ancient, well-known company, which maintains its leading position to this day, has its admirers. I soon learned that the Tannoy acoustics are still two-way, but the LF/MF and HF speakers are coaxial. From an engineering perspective, this solution turned out to be very attractive. Great solution. On the same network I read the praise of some and the disappointment of others of the owners of this acoustics after moving it from the salon to their home. I remembered that I myself appreciated the sound of Tannoy several years ago in the listening room of a store. Then I liked the Cornwall version of the American Klipsch more. And another understanding came - good acoustics do not always sound good (on different musical material and in different rooms), and this fact had to be somehow taken into account when designing your own speakers. For example, Tannoy is equipped with two controls for adjusting the midrange and treble.
Given the need to accept compromises, the intention was to create something similar to Tannoy Westminster or Canterbury. It turned out that you can order complete copies of Canterbury speakers at “affordable” prices in China. They even offer their own speakers. There were no reviews about the quality of the system and sound. I decided not to risk it. After analyzing the accumulated information, I began to search for the design of Tannoy acoustics. I found something for Westminster speakers, and in one Polish chat - 150 photos of the process of making a copy of this acoustics. The decision to repeat almost happened. Stopped planning the installation site. Still, Westminster is designed for a large space. Of course, it is possible to install them in a room in an ordinary apartment, but the discrepancy between the dimensions of the living space and the two huge speakers is striking. I have a private house and some are available free space to accommodate. However, this option (with difficulty) was rejected from implementation. Because of the size and the unavailability of native Tannoev speakers (as well as their high cost). In addition, the design will be largely guesswork (precise drawings are not available). Expect High Quality In this case, there is no sound. I wanted to have a controlled process. The study of the issue continued, but the coaxial Tannoy speaker did not give rest. Frankly, I continued to look for reasonable opportunities to purchase Tannoy heads until I came across the Spanish Beyma. This manufacturer offers a coaxial two-way speaker design that interested me. Here is a photo of a coaxially installed tweeter in the center of the woofer.
The characteristics of the reproduced frequency band were not as “chic” as those of the Tannoy. But, I remember, when in my youth my friends and I connected different heads to an audio frequency generator, we were surprised at the limited range of audible frequencies. The effect at low frequencies was especially interesting: significant movements of the speaker cone are visually observed, and at the same time there is practically no sound. Therefore, having had some doubts, I chose the 15XA38Nd speaker from the Spanish Beyma with a neodymium magnet. Of course, I was confused by the lack of traces on the Internet of using this speaker for home acoustics: both on Russian and Western resources. The power rating of the speaker was confusing: 350 W for low frequencies and plus 90 W for high frequencies. The head size was 15 inches. The lines I read from someone online remained in my head: “...transmission of the grandiose character of concert-scale sound is achieved with heads 12 inches and higher.” I agreed with this statement in my heart. And the parameters of Westminster and Canterbury confirmed the correctness of this phrase. It was also clear that the dimensions of the acoustics with these heads would be significant. But the characteristics of the speakers, their declared sensitivity of -99 dB, pushed aside the last doubts. The decision to take the risk was made. For those who are interested, you can find the characteristics of the head on the Internet or Audiomania.
I ordered the speakers and had to wait almost three months for delivery. At this time, the issue of acoustic design returned again. Without digression, I will say that the material “Rogozhin’s Labyrinth” seriously helped me confirm my choice. It can be easily found on the Internet. I do not provide a link, since the author asks for prior approval (although the material is available for free). But there, thanks to Rogozhin, both justifications and practical recommendations are given. I would venture to make a statement: this is the only material without water, to the point, with a full set of recommendations for practical results. Hence its popularity.
After this stage, the ordeal of making a decision was left behind. Ahead were the pleasant hardships of night acoustic calculations and speaker cabinet design.
A little "around the bush"
Everything stated above briefly represents the path traveled. I described it for those who are interested in creating a high-quality speaker system with their own hands and who are faced with similar questions. The process of developing the speaker from scratch is described here, and the path was completed completely until the creation of a prototype. Anyone who wishes can also walk the entire path, more consciously. It will be possible for someone to cut corners on it.
A few words about Rogozhin's labyrinth. The attractiveness of this design lies not only in the opportunity to obtain excellent acoustic sound results (I say this with understanding), but it also opens up the possibility of designing the appearance and internal architecture in the widest range. Ultimately, this technology allows you to create speakers “for yourself.” Some kind of custom tailoring. It is extremely convenient and attractive. Probably everyone understands the difference between purchased ready-made wardrobe and built-in or customized to specific requirements. The functionality and adaptability of the second option are higher. If you take into account the possibility of creating an appearance according to your requirements, connecting the appearance of the speakers, color with the interior in the placement area, the value of the option further increases.
I will not hide that the understanding of the goal during acoustic calculations according to Rogozhin’s recommendations should be clear. At the first stage, this is achieved by following the instructions given in the material and, already at the second stage, ... gained experience. In order to achieve the desired result, I had to perform many acoustic calculations to obtain the optimum and build six experimental options in order to reach the seventh - the final one. By comparing the results obtained in material and sound, you can clarify the calculations performed and make right choice option, adjusting it to your preferences, ensuring excellent sounding speakers.
For those who are not tired
Absolutely practical side. So, the choice of dynamic heads is behind us, and the choice of design (labyrinth channel) is also behind us. On Rogozhin’s recommendation, I installed the Hornresp program from an Australian developer. After following the step-by-step instructions, I got the first result. I will say this, almost blindly I had to perform at least a hundred calculations to meet all the requirements. What you need to strive for - the instructions were given by Rogozhin. Next I share my own experience.
First of all, a photo of the attempts made to find the desired sound:
Here are five housing options for one type of speaker. All options, except the last one (this is the sixth option, obtained by altering the fifth), are made in the size of 1520 mm in height (the height of the plywood sheet). The width and depth of the housings are different and depend on the design cross-section of the channel. The internal architecture is also different. The first option (the right body in the first photo) is made of 15 mm plywood. Body weight - about 70 kg (without finishing). All subsequent ones are 12 mm plywood and weigh from 35 to 55 kg. Light vibrations of minor surface areas on 12 mm thick speaker cabinets are present at a power supply of 100 W. To be honest, the developed sound pressure at such power in a limited space cannot be sustained for long. It's good that there are no neighbors behind the wall.
Thus, at a comfortable volume level, cabinet vibrations and overtones are not noted. By the way, no overtones were noted at any volume level.
Crossover debugging
The approaches and features of creating acoustic design for speakers were described above. It should be noted that the dimensions and weight of the speakers are impressive, the power of the speaker used is high. When acoustic systems were conceived, there was a belief that they needed to be listened to with an input power of 0.5 Watts. This circumstance was one of the limitations when choosing a speaker. There was doubt that a powerful speaker would provide effective work at low power input. Despite the available power reserve, the built speaker prototypes perform this function, providing excellent sound with minimal power input. Moreover, without detracting from the grandeur of the sound.
Currently, the resulting speakers are connected to a Sony amplifier, whose volume level is calibrated in decibels. Late in the evening, when there are no extraneous sounds, the acoustics sound great and bright at a volume of minus 66 dB. I would also like to note that the speaker power reserve guarantees operation of the speakers with minimal linear distortion at any volume at a comfortable level.
So, debugging the sound in the crossover.
I was initially disappointed with the set of speakers I received and the FD-2XA crossovers I ordered from the manufacturer (Beyma, Spain) for these specific speakers. The first turn on at low volume led to complete bewilderment. The sound was simply terrible. At low volumes there was almost no bass. As the volume increased, they turned into something completely absurd, emitting incredible muttering. There was no music as such.
After a 3-4 hour run at high volume (70-90 W), the speakers started working (warmed up). However, dissatisfaction with the sound did not disappear. No soulfulness, no grandeur of bass, no desired emotions. Only commendable sound detail.
As I mentioned earlier, sound development was carried out in two directions: search optimal parameters labyrinth and working with crossover. The labyrinth work is given above. The crossover also taught its lessons. His diagram was found on the Internet. It consisted of first-order filters with a matching circuit for the input complex impedance of a low-frequency loudspeaker. The crossover frequency, according to the Beyma website, is 1800 Hz.
Of course, I could describe in detail all the searches and adjustments of the resulting filters, but something tells me that such a presentation would be boring and uninformative. I will state it in the abstract.
- It turned out that after turning off the 15 microfarad capacitor, bass reproduction became more pleasant.
- Tests have shown that the acoustics produce audible distortion on some musical compositions. It was possible to establish that the distortion is caused by the high-frequency part of the speaker. Distortion disappears when the cutoff frequency of the high-pass filter is shifted to 2500 Hz and higher.
- To reduce the brightness, one might even say, the “loudness” of the speakers in the midrange, instead of a 2.2 µF capacitance, it is better to use a 0.68 µF capacitance.
After such changes, the sound became very good, but still not entirely satisfactory. An attempt to leave the woofer without inductance L1 did not further improve the sound of the speakers. However, the uneven frequency response of the speaker needs to be compensated. The manufacturer's inductance was kept in its place. Its influence is well felt.
And so, after a long period of listening to various genres, after trying to vary the values of the remaining filter elements right while listening, “on the fly,” so to speak, I turned off the RC matching circuit (8.2 Ohm and 8.25 uF - indicated in the diagram). The effect was amazing. The feeling of a loudspeaker sighing, having found freedom, previously held by some kind of noose. The previously held sound broke out, flew, became light and noble. It is impossible to convey in words the newfound lightness and virtuosity of the updated sound. Exactly that sound has appeared, from which an internal response arises, chills go through the body, and pouring music fills all the cells of the brain.
It should also be noted that the Beyma crossover inductors are not serious. They're wound up copper wire 1mm. For the woofer, the inductance parameters are 1 Ohm and 1.44 mH. At high powers, loss of bass energy is guaranteed. Taking into account the inductance parameters of the low-pass filter obtained by measurement, I ordered inductances for the low-pass and capacitances for the high-frequency sections of a higher class.
Total:
The work performed made it possible to adapt the parameters of the resonant channel to the selected speaker and ensured that the speakers sounded no lower than the expectations drawn by consciousness. I'll write about the sound below. All work took about five months (weekends and evenings, taking into account the presence of a fuse, time for listening and analysis, for the following calculations, etc.) and required certain costs. I can confidently say that the sound level corresponds to acoustics in the price range of two million rubles. Actual costs, especially taking into account existing equipment, are disproportionately lower. The path traveled was not easy. The created speaker sounded not only thanks to the accurate or successful calculation of the resonant channel, intuitively, to some extent, the chosen speaker, and its approach to modeling and manufacturing the body. Let me remind you that the built acoustic system is a two-way system, the presence of a crossover is mandatory. Working with the crossover also allowed me to contribute to the final sound and gain useful experience. Damping was not used in the speaker design. Perhaps I will make an attempt to evaluate the effect of damping in a specific case. I can say that the accumulated experience made it possible to evaluate the two options mentioned at the beginning of the manufactured speakers for the 75GDSh3-1 speakers, to see the shortcomings of the bass settings and to make adjustments.
Currently there is no ready-made front speaker option for the 15XA38Nd speaker. There is a project. A new calculation has been made for speakers with a 75GDSh3-1 speaker with increased bass output. The new variant will be equipped with a tweeter. Taking into account the existing workload and delivery of additionally ordered components, these projects will be implemented no earlier than October-November current year. The results will be presented. Part of the speaker cabinet design for the 15XA38Nd head is shown below:
Sound
It is possible that I have developed sentimentality. The achieved sound of two-way speakers on one track or another led to mental and heart trembling, to holding one's breath, and provoked repeated listening to the compositions one liked. The correct or incorrect sound is not discussed. If the sounding speaker evokes in the listener the conviction of reality from the heard music, vocals, sounds and overtones, the goal has already been achieved. If individual turns of a musical program can dry out the throat and make the eyes wet, the task has been completed to the maximum. I am inclined to believe that the built prototypes of future speakers are close to the coveted maximum.
Frankly, if I had not received such a result, I would not have allowed myself to openly share my work. Perhaps someone will say, beginners are lucky. I was doubly lucky. Two pairs of magnificent speakers based on 75GDSh3-1 speakers, released in Soviet times, which endured 35 years of stage life, and a pair of new ones, based on 15XA38Nd speakers from the Spanish Beyma. Let him be lucky, but for those who consider it possible to make such speakers, taking into account the additional recommendations provided in the material, the result is guaranteed. It is for such people that I write.
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