Drawings of two-way speakers with a subwoofer inside. DIY active computer speaker. Didn't find what you were looking for? google it

There are many sound systems on today's market for acoustic equipment - they can be of different types, power and design; you can choose speakers to suit every taste and every need. However, purchased speakers are not always the ideal option. Many people want to try making acoustic devices with their own hands - from the realization that this is not a product from a Chinese factory, but something created on their own, the speakers will even begin to subjectively sound better.

Of course, buying speakers is much easier and probably cheaper. But building your own speakers isn't that difficult. The complexity of the process depends on several factors:

• What speakers do you need? Whether you want to assemble a full-fledged multi-channel system or a simple stereo pair, they should be powerful or not, broadband or multiband. First of all, the complexity of the calculations depends on all this, and then the complexity of the assembly.
• Number of parts available. The scale of the project can be different - someone assembles only the housing and buys the electrical parts ready-made, while others even make the control chip (crossover) and amplifier themselves. The only thing that is purchased in all cases is dynamic emitters, since it is almost impossible to assemble them outside the factory.
• Experience and skills. The main thing you need to have is straight hands, capable of doing woodworking at a decent level, since in the case of assembling speakers with your own hands, the final quality of the speaker system depends on the quality of the housing.

If you are sure that you are ready to assemble the speakers yourself, you need to prepare the tools and materials, and you can get started. Let's leave aside the question of what type the final result will be. acoustic system– it doesn’t matter, the general principles of assembly are similar regardless of whether small front speakers or a huge and powerful system 5.1. In principle, only the volume of work and the number of calculations will differ.

Speaker design

Before you start making acoustic devices with your own hands, you need to figure out what they can be made of and in what form. First of all, you should find out what the speaker body can be like.

The quality of the cabinet plays a huge role in giving the sound purity and volume. If the box is assembled with gross design errors, the consequences can be very different - from a simple deterioration in sound quality (for example, it will be too muffled) to complete inoperability of the speaker. Don’t worry ahead of time - having calculated everything exactly, everything will work out in a very decent time. If there are any flaws, it is unlikely that they can be identified with the naked ear. It is also worth remembering that when working with wood, a decimeter of error is not an error, so minor errors are quite forgivable.

The first thing you need to choose is the shape of the future columns. It can be almost anything, but for independent work it is best to choose a traditional rectangular shape. If you plan to manufacture not a broadband speaker, but a subwoofer, then the shape should be cubic. Please also note that when making a low-frequency speaker, the most accurate calculations of the volume of the speaker, as well as the bass reflex, are required, otherwise the bass will not be reproduced well enough, which will defeat the purpose of the work.

Column sizes may also vary. If a large set of speakers will be used - up to three midrange speakers, one high-frequency tweeter and a low-frequency subwoofer - the speaker, of course, must be tall. At the same time, it can be narrow - the volume is quite enough for high-quality sound. In general, there is a lot to be said about calculating volume - but all the particularly accurate calculations are of little use if you do not have ears that can detect the slightest deviations in the amplitude of the sound from a perfectly straight line. So it’s enough to roughly calculate the required volume based on the diameter and power of the dynamic emitter. If the speaker is multi-way, the subwoofer is used as the basis.

One of the most important points - right choice material. The walls of the speaker housing can be made of different types of material, the main thing is that it meets three requirements:

• rigidity - so that the walls do not bend under the influence of vibration of the speakers;
• ease;
• affordable price.

Medium-density particleboard, or MDF, is best. Solid wood is not suitable because it is too flexible and creates a resonance effect. In addition, the column is not an absolutely static object - during operation, vibrations and similar movements that are invisible to the naked eye always occur in it, which is why unpressed wood dries out relatively quickly and becomes unusable. One of the few types of wood that can be used to make a DIY speaker is ebony, or ebony, which is the hardest of all types of wood and also polishes perfectly. However, ebony is very expensive, so in most cases it will not be suitable - after all, one of the goals of independent work is cost-effectiveness.

Another possible variant material – multilayer plywood. It is easy to process, and after assembling the body, it can be finished with any decor - for example, natural veneer. Its only drawback is that it is not the highest rigidity, so for greater structural strength, you will have to additionally cut out ribs that will be placed inside the box.

In addition to the materials described, it is possible to use GVL or DSP - they themselves have good sound insulation properties, which allows you to save somewhat on protective material. However, they are heavy and very difficult to process. It is not recommended to use plastic at all - we will leave polymers to factory manufacturers. Thus, it is best to opt for chipboard, especially laminated chipboard - it has better properties and looks good, imitating almost any material - for example, ebony.

As a result, the column should have the following qualities:

• Smooth amplitude-frequency response - this parameter reflects the sound quality, since it represents the difference between the received electrical signal and the sound waves produced. It is to obtain an ideal frequency response that all efforts should be directed when making a homemade speaker. The quality of the frequency response is influenced by many factors - the correct location of the speaker parts inside the housing, the quality of the materials used, and even the environment.
• Decent efficiency. Since in dynamics the electrical signal is converted into mechanical movements of the diffuser - vibrations of its membrane, which create sound - coefficient useful action always turns out to be quite low. You need to try to raise it as high as possible. The correct selection of parts can help with this.
• Subjective sound quality - the speaker should be pleasant to listen to, because it will not be a device for measuring sound characteristics that will be used, but you yourself.
• Nice design - the more attractive the speaker looks, the more pleasant it will be to use.

Having fully prepared for work and having drawn up an approximate design of the column, you can begin making the column with your own hands.

Acoustic device technology

One of the main principles to be followed when working is accuracy. You need to take all measurements as carefully as possible before you start cutting out the parts, and before attaching them you need to try everything on to each other.

The stages of column manufacturing are as follows:

1. The walls of the future building are drawn on prepared chipboard sheets. On the walls you need to mark places for installing speakers - the holes should be round and ideally fit the size of the emitters, so that in the end there are no gaps.
2. The details are cut out. If the board is varnished, it is better to saw it with the finished side up so as not to damage the decorative coating.
3. How to fasten the walls of the column? You can use two methods: either use glue or epoxy resin, or simply screw it together with screws. In the first case, you need to do everything very carefully so that the column does not become warped. To press the glued parts together, you can use a vice system. You also need to carefully fasten the walls with thin screws so that they fit in at a perfectly right angle.
4. The case must be sealed, therefore, if the joints of the walls are not tight enough, the cracks must be filled with felt soaked in glue. If the back panel is removable, you need to stick a polymer or rubber seal along its edge.
5. If the box is closed, instead of upholstering the walls with sound insulation, cotton wool or foam rubber can be filled directly, filling the entire volume of the speaker. The main thing is that it does not come into contact with the rear surface of the diffuser. In addition, a channel must be formed from the emitter to the bass reflex.
6. It is not necessary to calculate the length of the bass reflex - it is perfectly selected experimentally. The diameter is easy to calculate - for example, for a speaker with a diameter of more than 100 mm, a pipe 5 cm wide is perfect. The length is determined as follows - two homemade cardboard tubes are taken and inserted into each other, and then placed in the hole intended for the bass reflex. Then the column must be turned on and the tubes must be moved relative to each other until the air flow from the hole becomes most active.
7. Once the case is assembled, all that remains is to place the speakers and amplifier in it. The emitters are connected either in series or in parallel, depending on the required characteristics of the speaker.

If you follow the technology, you will undoubtedly get a very high-quality speaker.

Making your own speakers: video

High-quality sound speakers for home sound reinforcement equipment reproduce low-frequency signals with a frequency of 30-50 Hz, which corresponds to a sound wavelength of 7-10 m. To effectively emit such vibrations, dynamic heads with a large diffuser diameter are needed (there are examples with a diameter of 400 mm). However, in practice, “speakers” ranging in size from 200 to 300 mm are most often used. Their natural resonant frequency is 15-30 Hz.

When a sound signal is applied to the head, its moving system oscillates, emitting in both directions sound vibrations that are equal in strength but opposite in phase, which are non-directional. The “speaker” housing is not able to isolate areas of air compression and rarefaction from one another. As a result, at the listening point the sound pressure has low level. This phenomenon is known in the art as an acoustic short circuit. This is eliminated by placing the acoustic emitter in a closed box (Fig. 1). (The symbols in the figures indicate: a - width, b - depth, c - height of the box, x - thickness of the material, (1 - thickness of the strip). Often one or even several holes are made in it, placing them in certain places in the body (Fig. 2). Such holes are called phase inverters, or bass reflectors. Their variety is a passive radiator (Fig. 3), which is an unconnected dynamic head. The location of the holes on the front panel of the speaker body is chosen so that the back radiation coincides with the front radiation, increasing thereby low-frequency sound pressure.

Important for acoustic speakers are their size, shape and materials from which they are made, internal “filling” and design of the front panel. Thus, the housing influences the technical parameters of the dynamic head installed in it and, above all, increases its own resonant frequency. An important role here is played by the diameter of the diffuser and the displacement of the housing. With an increase in its volume and a decrease in the size of the moving system, the resonant frequency changes slightly. If a head with a large diffuser is installed in a relatively small box, the resonant frequency will change noticeably - low frequencies are “cut off”, and as a result, the effective frequency range of the speaker is narrowed. In other words, an incorrectly selected housing can degrade the playback quality of even a very good dynamic head.

For effective head output at low frequencies, Bulgarian radio amateurs recommend choosing column volumes based on the data given in the table.

When using a bass reflex, certain requirements must also be met. The hole for it should be located at a distance of at least 60-80 mm from the woofer head and 40-50 mm from the rear wall of the housing. Sound-absorbing material is also placed at the same distance from the hole. It is better if the bass reflex is located under the woofer head.

Recommended sizes for bass reflex speakers depend on the volume of the speaker and the diameter of the head diffuser. So, with a head d 125 mm installed in a housing with an internal volume of B dm3, the bass reflex pipe has d 50 (46) mm and b = 60 mm. For a loudspeaker with a volume of 16 dm3, the diameter of the diffuser is 160 mm, you need a pipe d 50 mm and length 100 mm. Accordingly, for a head d 200 mm with a volume Y = 30 dm3, the pipe dimensions will be d 75 mm, b = 100 mm. The loudspeaker has d 300 mm, with N4 = 60 dm3 the pipe should have d 75 mm and b = 220 mm.

The shape of the cabinet, both internal and external, also affects the frequency response of the speaker. The most acceptable is spherical, and the most unsuitable is a cube, when the dynamic head is located in the geometric center of one of its sides. In a cylindrical body, the most favorable location of the head is transverse (Fig. 4a), rather than longitudinal (Fig. 46), although attaching it in the latter case is much simpler.

If the housing has the most common parallelepiped shape, it is best to install the low-frequency “speaker” asymmetrically relative to the sides of the reflective board (Fig. 1).

A type of parallelepiped-shaped column is shown in Figure 5.

A loudspeaker with a housing in the form of a triangular prism (Fig. 6) or a truncated pyramid (Fig. 7, 8) has good acoustic data.

For a volume of 5-10 dm3 and a “speaker” power of 6-10 W, a box wall thickness of 8-10 mm is sufficient, and for V = 40-60 dm3 and a power of 40-100 W, the rest are made of plywood or chipboard. However, with large dimensions of the case and significant power of the dynamic head, unwanted vibrations may still occur in it. To avoid them, the walls of the column are tightened with wooden slats with a cross-section of 40 X 40 mm or metal rods d 6-10 mm (Fig. 10).

Bass reflexes are made of plastic or metal (for example, duralumin) pipes with a wall thickness of at least 2 mm.

Minerals are also used as a material for building columns. Marble comes first. Thanks to its layered structure, it dampens sound well and therefore does not experience resonant vibrations. Marble is easy to process, but the disadvantage is that it is heavy and fragile.

The walls of the case are connected to each other using one of the methods shown in Figure 11. It is easier to make a box with removable front and rear panels.

First, cut out the side walls. Before assembly, it is necessary to glue and then nail with small nails restrictive mounting rails measuring 15X15 or 20X20 mm and the length indicated in Figure 12.

The walls of the body are glued together with Universal or S-200 glue and thin nails are driven in every 15-20 mm for greater reliability of fastening. The box will be even stronger if additional bars are glued into its corners (Fig. 13). Free spaces are filled with epoxy. Based on the covering assembled in this way, the dimensions of the front and rear panels are determined. They are made from coniferous wood. Based on the existing dynamic heads, the location of the holes for them is outlined (Fig. 14).

Speakers are often decorated with decorative frames made of wooden slats with a cross-section of 15x15 mm. The radio fabric is stretched over a reflective board and secured with buttons or furniture nails.

The internal volume of the speaker is filled with some sound-absorbing material, for example glass wool. Its quantity is determined by measuring the resonant frequency. The filling of the body is considered normal if it has decreased by 10-12%. It has been experimentally established that this will require 30-40 g of glass wool or 10-15 g of polyester wool (yambolene) per 1 dm3. You can also use rags. Sound-absorbing material is placed in a thick fabric cover.

If the dimensions of the housing are correctly selected and it is carefully sealed, then when you gently press the diffuser of the low-frequency head, its moving system smoothly returns to its original position. The absence of such a phenomenon indicates the presence of acoustic losses, which reduce sound pressure at low frequencies by 1-2 dB.

Do-it-yourself bookshelf acoustics

DIY or Do It Yourself

One day I decided to build myself high-quality acoustics for sounding a small room, as well as for use as near-field monitors when working with sound on a computer (hobby). The main requirement is adequate sound in relation to the source. Not so that “the lower classes are wobbling” or “cymbals are ringing”, but rather adequate natural sound. So, we collect high-quality “shelf holders”.

Number of lanes

In theory, the ideal system is single-band. But, like everything ideal, such a system does not exist in nature. Yes, there are very high-quality broadband speakers from the same "Visaton", but for some reason all well-known manufacturers make two-way bookshelf systems. And when it comes to the floor option, then 3 stripes are not uncommon. There wasn’t much of a question here – the classic two-band version: low-frequency and high-frequency.

Speaker selection

The main requirement for speakers is an optimal price/quality ratio. Those. it shouldn’t be “cheap” for 500 rubles, but also not a mind-blowing “high-end” for $1000. Besides, I was in no hurry. Thought to collect with my own hands“half-timers” arrived quite a long time ago, and I cast the bait in advance to my good friend, “sick” with sound, with whom we have been constantly and fruitfully communicating on this topic for a long time.

The first to appear was the HF - Vifa XT19SD-00/04 ring-rad. These are high-quality 4-ohm tweeters, quite popular among audiophiles. They were planned for one set, but for some reason they didn’t work out and ended up in my set.

LF arrived second. They turned out to be very decent midbass from the Soundstream Exact 5.3 kit. Here you can read a little about them. It so happened that the tweeters burned out during installation, and the lone woofers themselves turned out to be unnecessary. 4-ohm 5.5" midbass mounted in a cast aluminum basket were immediately purchased.

Now that you have the speakers, you can start creating acoustics.

Active / passive?

Each option has its pros and cons. Firstly, you need to take into account the compactness of the speakers themselves and the associated difficulties in layout in limited space. There is no point in installing it outside. Secondly, individual modules as independent components can be combined in the future, and it is also easier to repair if something happens. And thirdly, active speakers are quite expensive. Because if you make a decent amplifier (and sometimes there is one in each case), then it will turn out to be more expensive than the acoustics themselves. Besides, I already had an amplifier. But in any case, I am in favor of the scheme - passive acoustics + amplifier, it is more universal.

Calculation of housing dimensions

We have decided on the speakers, now we need to understand which housing is optimal for them. Dimensions are calculated based on the sound characteristics of the woofer. There are no recommendations on the manufacturer's website, because... The speaker was intended primarily for car audio. There is no point in keeping special equipment for these purposes unless it is your job. Therefore, a smart guy with a special stand comes to the rescue. As a result of laboratory tests, we obtain a calculated case size of 310 x 210 x 270 mm. During the measurement process, the bass reflex parameters were also calculated.

By the way, many manufacturers publish recommended housing sizes for speakers on their websites. When such information is available, it is logical to use it, but in this case I did not have such data, so I had to do laboratory research.

Housing material

In my opinion, the most optimal material for the case is MDF. It is acoustically neutral and also performs slightly better than chipboard. Plywood is also good, but quality plywood is not easy to find and is more expensive and difficult to process. 22mm MDF sheet was chosen as the source material for the body. In principle, standard 18-20mm is quite enough, but I decided to make a little extra. There is no such thing as too much rigidity.

Housing construction and design

One of the most important stages. Before going for MDF, I advise you to decide on the design so that you can immediately ask the seller to cut the sheet in parts, and at a normal point of sale there are always good machines with accurate and even cuts. It is difficult to obtain such a cut at home.

So, design. The speakers should look at least as good as “industrial” ones, so that there is no feeling of a club of crazy hands. We make not only high-quality, but also beautiful acoustics. In general, there are practically no beautiful, interesting and at the same time structurally simple acoustic systems. Beautiful acoustics are made by the Italian Sonus Faber, stunning in beauty - Magico Mini. But they are all made using precision machines, which, by definition, are not available at home. As an option, you can order the cases from a good “cabinet maker” with hands and CNC. Depending on where and what you order, such work will cost from 10,000 rubles. up to 30,000 rub. along with materials. If the specialist is good, then the speakers will look no worse, or even better, than store-bought ones. In this case, I decided that I would do everything completely myself. Therefore, we look at things realistically and make a design without any bevels, curly cuts, etc. Those. it will be a parallelepiped. The calculated dimensions give a fairly pleasant proportion, and proportion in the design is already half the battle.

What to design in? Although I am related to design by line of work, my knowledge of 3D packages is, to put it mildly, superficial. In this case, the program should be more engineering than rendering. Specialized "Kads" for this purpose are heavy and unnecessary. A solution was found quickly enough - frivolous SketchUp is more than suitable for this purpose. It is so simple and intuitive that I was completely mastered in about an hour. The main thing he can do is quickly create any shapes, set dimensions, use simple textures. I believe that such a program is ideal for “home” purposes. You can easily use it, for example, to design a kitchen or even a small house.

Here is the body design:

Based on the drawing, a diagram of cutting the sheet emerges:

In general, the options are not bad in appearance, but purely structurally they cause difficulties. As a result, it was decided to trim the side walls with ash veneer, and cover the remaining 4 walls around the circumference with leather, or rather with high-quality automotive leatherette. The arquebus is beautiful in itself, but the woofer has a structural overlay on the front side of the housing that will not look very nice. Therefore, it was decided to make an additional decorative overlay (ring) for it, which will press it to the body, and at the same time add beauty to the speaker itself. The construction and design have been decided.

Tools

Before moving on to the next stage, I’ll outline what basic tools are needed for the job:

Circular.

Jigsaw.

Sanding machine.

Straight arms.

Without this kit, it is better to order the cases from a good craftsman.

Sawing

So, we cut the budget MDF sheet. I have already written that it is better to saw on special machines - it is inexpensive, but the results are accurate. But because I decided to make the body myself inside and out, then for the purity of the experiment I sawed it myself with a manual circular saw, and small pieces with a jigsaw with a guide. As expected, the perfect cut did not work out. After the cut, pairs of walls (left-right, front-back, etc.) are installed in pairs, adjusted with a grinder and/or electric planer and checked for perpendicularity with a square. And later during assembly they are finally adjusted after gluing. A loss of 2-3 mm is insignificant. But I still recommend sawing right away “at the base”, you will save a lot of time.

Housing assembly

The walls are glued together with PVA and tightened with screws. First we glue the body without the front wall.

Now there is a hole for the terminal block, as well as a chamfer in order to “sink” it. Initially, according to the design, the terminal block was supposed to be placed at the bottom. But during the process, it became clear that mounting the crossover in the center through the hole for the woofer would not be very convenient, so I moved the hole for the terminal block higher, and the place for the crossover lower.

You can close the box.

Now one of the very important stages is cutting out the holes for the speakers on the front panel. I have already said that the ideal speaker system is a single-way one. Why? Because sound propagates from one source to the listener without a time mismatch due to the (tiny) difference in distance that occurs when using a multi-band system. Therefore, it is best to place the speakers as close to each other as possible. This makes the sound image “dense.” We calculate the holes so that the distance between the edges of the speakers will be approximately 1 cm. The holes are cut with a jigsaw with a circular guide.

After the chamfers are removed, we attach the terminal block and speakers, and then drill holes for future self-tapping screws with a thin drill. Without them, firstly, the MDF itself may “spread open” when screwing in the screws, and secondly, during the final installation the speakers will be more difficult to position evenly. I thought for a very long time about how to position the speakers relative to each other, and came up with the following scheme:

Screw holes on external surfaces must be repaired before final finishing. I used epoxy. In order not to wait for one surface to harden, I sealed each surface with tape and moved on to the next one. When the epoxy had dried, I sanded it with a sander.

The veneer needs to be protected. I coated it with clear yacht varnish.

Now you need to cover the body with leatherette. There are many options for how to do this. I decided to do it as follows. A strip is cut 20 mm larger than the width of the case and slightly longer than the circumference of the case. On each side it is folded by 10 mm, the hem is glued with “special glue 88”. Then, using the same glue, the strip is glued around the circumference to the body. First the bottom (partially), then the back wall, then the top, then the front and the bottom again. At the last stage before gluing, the strip is cut in place and glued end-to-end. I glued all sides at once, i.e. didn't wait for each side to dry. After each side I took a short break (the glue sets quite quickly) and started on the next one.

If you really want to, then the phasic can be somehow refined.

Then holes are cut on the terminal block, “woofer” and “tweeter”. The skin on the terminal block and RF will be recessed downwards, so the diameter of the cutout can be left 5-10 mm smaller. The skin on the woofer will be pressed against the decorative ring, so you need to trim it so that it is not visible.

Final editing

First of all, we mount the crossover. Cross - homemade, on good element base. Air-core coils, tweeter film capacitors and MOX resistors are used. I didn’t solder it myself, but ordered it from smart guys.

Now we solder the required pair of wires to the terminal block and fix it on the body. The terminal block and speakers are screwed on with decorative black self-tapping screws with an asterisk head. The cover on the “squeaks” is screwed with similar screws, so it would be logical to use the same ones for the rest. The back wall is ready.

The midbass needs to be slipped under the skin, and pressed down on top with a decorative ring. Solder the remaining couple of wires and mount the speaker.

All? All. We screw the acoustic cable to the terminal block and begin testing.

Tests

The system was tested in the following configurations:

1. Receiver Sherwood VR-758R + acoustics.

2. Computer + Unicorn (USB-DAC) + Homemade stereo amplifier + acoustics.

3. Computer + E-mu 0204 (USB-DAC) + Sherwood VR-758R + acoustics.

A little about the configurations themselves. I personally think that on this moment The ideal option for a home music center is: computer + USB DAC + amplifier + acoustics. Digital sound without distortion is captured via USB and sent to a high-quality DAC, from which it is transmitted to a high-quality amplifier and then to the acoustics. In such a chain the amount of distortion is minimal. In addition, you can use completely different soundtracks: 44000/16, 48000/24, 96000/24, etc. Everything is limited by the capabilities of the driver and DAC. Receivers in this regard are a less flexible and obsolete option. The size of modern hard drives allows you to store almost your entire media library on them. And trends towards subscription to Internet content may eliminate this option, although this is not in the near future and is not suitable for everyone.

I will say right away that in all three configurations the acoustics sounded great. To be honest, I didn't even expect it. Here are some subjective aspects.

1. Adequate and natural sound. What is recorded is what is played back. There are no distortions in any direction. Just as I wanted.

2. Greater sensitivity to the source material. All recording flaws, if any, are clearly audible. High-quality mixed tracks are listened to perfectly.

3. Well-readable bass for such sizes. Of course, you can’t fully appreciate organ music on bookshelf speakers (it’s generally difficult to appreciate it on acoustics), but most of the material can be “digested” without problems. It's hard to expect more from such babies.

4. Very good attention to detail. You can hear every instrument. Even with a rich sound image and decent volume, the sound does not turn into a mess (the amplifier plays an important role here).

5. I would like to make it louder;) That is. The acoustics do not scream, but play smoothly. Although this is also not a small merit of the amplifier itself, because with increasing load good amplifier maintains linearity.

6. Long listening does not give you a headache. Personally, this often happens to me, but here it plays all day and nothing happens.

7. Concerns about incorrect panorama and strong dependence of the sound on the position of the listener were not confirmed. As far as I know, car acoustics have a specific sound phasing due to the location of the speakers in the cabin. Namely, I read about this set that its midbass is more universal in this regard. Which was actually confirmed. You can sit in the center in front of the speakers, or stand next to them sideways - the sound is excellent. There is a dependence, but it is very small.

As for the configurations themselves, the highest quality sound was achieved with the second configuration.

Firstly, a very high quality Unicorn DAC was used.

Secondly, the “home-made amplifier” is the know-how of one smart Tolyatti “sound specialist”. Here it is in a nice little aluminum case:

In a nutshell, we were able to find a circuit solution in which the amplifier retains its characteristics when the volume changes, i.e. does not distort the sound at any (constructively permissible) volume. Many amplifiers (even very expensive ones) suffer from this. It was amazing to hear how such an amplifier brought many speakers to life, i.e. made them sound the way they should sound. By the way, some industrial amplifiers (in particular, the Xindak, which is quite good in itself), were also rebuilt according to this scheme, and they got a “second wind”.

Have you compared acoustics with something else, you ask? Yes, for example, with ProAC Studio 110 – these are quite high-quality bookshelf acoustics, here’s a little about them. We compared them and realized that they definitely sound no worse. The “Proaks” may have a slightly lesser dependence of the sound on the position of the listener due to the specific placement of the inverter and the “tweeter”; somehow they cleverly calculated all this. As for the rest, it’s absolutely no worse, even I personally liked my homemade products better, but we’ll chalk that up to subjectivity;) I also put on headphones (quite good Koss) and compared them by panorama, highs and lows. Absolutely identical sound. Even at the bottom. In general, complete delight.

Costing by materials

Mid/bass speakers (pair): 3,000 rub.

HF speakers (pair): 3,000 rub.

Crossover (pair): 3,000 rub.

Sintepon: 160 rub.

Terminal (terminal block): 700 rub.

Screws: 80 rub.

MDF sheet, 22mm: RUR 2,750.

Scotch tape: 30 rub.

PVA: 120 rub.

Special glue 88: 120 rub.

Vibration isolation: 200 rub.

Figured ring-onlay: 500 rub.

Cable: 500r.

Total: 14,160 rub.

Some materials were or were received free of charge and accordingly are not taken into account here.

In custody

In any more or less complex device or complete functional system absolutely everything is important. When it comes to a music system, the final result is influenced by a large number of factors:

Soundtrack quality.

A device for playing a phonogram.

Digital-to-analog converter.

Signal amplifier.

Wires.

Speakers installed in the acoustic system housing.

Correctly designed for speakers and high-quality assembled housings.

Diagram and accessories for the crossover.

This is a basic but not complete list.

It is wrong to think that the main thing is the amplifier, or the main thing is the wires, or the main thing is the speakers. A home music system is like an orchestra. And if in this orchestra some people play poorly and others play brilliantly, then overall the result will be average. Or, as they said in a very precise example: if you mix a barrel of shit with a barrel of jam, you get two barrels of shit.

There is another extreme. Good system costs fabulous money. This means that each component should cost half a million. And phonograms must be exclusively on Super Audio CDs or branded records. Like a closed society of elite audiophiles. This is all bullshit.

I came to the conclusion that building your own is relatively budget system, which is described in one word “Sounds”, is quite possible. And if, due to its features, it is better to use a real one as a DAC or amplifier existing solutions, of which there are a lot now. Then a correctly made (either independently or to order) acoustic system will sound better than a “branded” one purchased for the same money. Nowadays almost all components can be ordered online. Moreover, many manufacturers publish enclosure diagrams for their respective speakers. There are a lot software to calculate housing parameters. There are many specialized forums online, and offline there are people with hands. Of course, it is impossible to be an expert in everything. As in any field, the main thing is to know the general principles.

The article does not claim to be the ultimate truth, but I hope that my thoughts and my experience will be useful to someone else.
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Greetings to Datagor readers! I want to tell you about creating an acoustic system using 3D printing technology. Using a 3D printer, I was able to build an unusual acoustic system in the shape of a ball, as well as solve a number of additional problems that arise when making acoustics.
I would like to note that I am not at all advocating the use of plastic as the main material for building speakers.

Ever since my student days I had a dream - to make speakers in the shape of balls. But the methods available to me at that time for creating a custom-shaped case did not inspire me in any way. And now, many years later, I got a 3D printer.

Now here is my translation of Troels Gravesen’s article about “the world’s worst dome tweeter Philips AD 0160.” I think he didn’t come across Soviet, or even many modern tweeters.
Most likely, few people have this particular tweeter (tweeter, not to be confused with Twitter), but Troels’ research will be useful for home-made people to evaluate the quality and proper use of tweeters.

Best regards, Sergei

I'll show you with a real example what you can do with old speakers, namely their drivers, to get improved sound.

1. Column or speaker?
2. Acoustics and electronics
3. What is hi-fi
4. Speakers
5. Acoustics

Making sound speakers with your own hands - this is where many people begin their passion for a complex, but very interesting matter - sound reproduction technology. The initial motivation is often economic considerations: prices for branded electroacoustics are not excessively inflated, but outrageously brazen. If sworn audiophiles, who do not skimp on rare radio tubes for amplifiers and flat silver wire for winding sound transformers, complain on forums that the prices for acoustics and speakers are systematically inflated, then the problem is really serious. Would you like speakers for your home for 1 million rubles? pair? If you please, there are more expensive ones. That's why The materials in this article are designed primarily for very beginners: they need to quickly, simply and inexpensively make sure that the creation of their own hands, all of which cost tens of times less money than a “cool” brand, can “sing” no worse or at least comparable. But probably, some of the above will be a revelation for the masters of amateur electroacoustics- if it is honored with reading by them.

Column or speaker?

A sound column (KZ, sound column) is one of the types of acoustic design of electrodynamic loudspeaker heads (SG, speakers), intended for technical and informational sounding of large public spaces. In general, an acoustic system (AS) consists of a primary sound emitter (S) and its acoustic design, which provides the required sound quality. Home speakers for the most part look like speakers, which is why they are called that. Electroacoustic systems (EAS) also include an electrical part: wires, terminals, isolation filters, built-in audio frequency power amplifiers (UMPA, in active speakers), computing devices (in speakers with digital channel filtering), etc. Acoustic design of household speakers They are usually placed in the body, which is why they look like columns more or less elongated upward.

Acoustics and electronics

The acoustics of an ideal speaker are excited over the entire range of audible frequencies of 20-20,000 Hz by one broadband primary source. Electroacoustics is slowly but surely moving towards the ideal, but the best results are still shown by speakers with frequency division into channels (bands) LF (20-300 Hz, low frequencies, bass), MF (300-5000 Hz, mid) and HF (5000 -20,000 Hz, high, high) or low-midrange and high-frequency. The first, naturally, are called 3-way, and the second - 2-way. It’s best to start getting comfortable with electro-acoustics with 2-way speakers: they allow you to get sound quality up to high Hi-Fi (see below) at home without unnecessary costs and difficulties (see below). Sound signal from UMZCH or, in active speakers, low-power from the primary source (player, sound card computer, tuner, etc.) is distributed among frequency channels by separation filters; this is called channel defiltering, just like the crossover filters themselves.

The rest of the article focuses primarily on how to make columns that provide good acoustics. The electronic part of electroacoustics is the subject of a special serious discussion, and more than one. Here you only need to note that, firstly, at first you do not need to take on close to ideal, but complex and expensive digital filtering, but use passive filtering using inductive-capacitive filters. For a 2-way speaker, you only need one plug of low- and high-pass filters (LPF/HPF).

To calculate the AC separation ladder filters, there is special programs, eg. JBL Speaker Shop. However, at home, individual tuning of each plug for a specific instance of speakers, firstly, does not affect production costs in mass production. Secondly, replacing the GG in the AC is required only in exceptional cases. This means that you can approach filtering the frequency channels of speakers in an unconventional way:

1. The frequency of the LF-MF and HF section is taken to be no lower than 6 kHz, otherwise you will not get a sufficiently uniform amplitude-frequency response (AFC) of the entire speaker in the midrange region, which is very bad, see below. In addition, with a high crossover frequency, the filter is inexpensive and compact;
2. The prototypes for calculating the filter are links and half-links of type K filters, because their phase-frequency characteristics (PFC) are absolutely linear. Without this condition, the frequency response in the crossover frequency region will be significantly uneven and overtones will appear in the sound;
3. To obtain the initial data for the calculation, you need to measure the impedance (total electrical resistance) of the LF-MF and HF GG at the crossover frequency. The GG indicated in the passport are 4 or 8 Ohms - their active resistance is DC, and the impedance at the crossover frequency will be greater. The impedance is measured quite simply: the GG is connected to an audio frequency generator (AFG), tuned to the crossover frequency, with an output of no weaker than 10 V into a load of 600 Ohms through a resistor of obviously high resistance, for example. 1 kOhm. You can use low-power GZCH and high-fidelity UMZCH. Impedance is determined by the ratio of audio frequency (AF) voltages across the resistor and GG;
4. The impedance of the low-frequency-mid-frequency link (GG, head) is taken as the characteristic impedance of the low-pass filter (LPF), and the impedance of the HF head is taken as the head of the high-pass filter (HPF). The fact that they are different is a joke; the output impedance of the UMZCH, which “swings” the speaker, is negligible compared to both;
5. On the UMZCH side, low-pass filter and reflective-type high-pass filter units are installed so as not to overload the amplifier and not take power away from the associated speaker channel. On the contrary, the absorbing links are turned to the GG so that the return from the filter does not produce overtones. Thus, the low-pass filter and high-pass filter of the speaker will have at least a link with a half-link;

When getting into electroacoustics, you need to know the following about how speakers are structured and work in acoustic systems. The speaker exciter is a thin coil of wire that vibrates in the annular gap of the magnetic system under the influence of audio frequency current. The coil is rigidly connected to the actual sound emitter into space - a diffuser (at LF, MF, sometimes at HF) or a thin, very light and rigid dome diaphragm (at HF, rarely at MF). The efficiency of sound emission strongly depends on the diameter of the IZ; more precisely, from its ratio to the wavelength of the emitted frequency, but at the same time, with an increase in the diameter of the IZ, the probability of the occurrence of nonlinear distortions (ND) of sound due to the elasticity of the IZ material also increases; more precisely, not its infinite rigidity. They combat NI in IR by making radiating surfaces from sound-absorbing (anti-acoustic) materials.

The diameter of the diffuser is larger than the diameter of the coil, and in diffuser GGs it and the coil are attached to the speaker body with separate flexible suspensions. The diffuser configuration is a hollow cone with thin walls, with its apex facing the coil. The coil suspension simultaneously holds the top of the diffuser, i.e. its suspension is double. The generatrix of the cone can be rectilinear, parabolic, exponential and hyperbolic. The steeper the diffuser cone converges to the top, the higher the output and the lower the dynamics of the speaker, but at the same time its frequency range narrows and the directivity of the radiation increases (the radiation pattern narrows). Narrowing the pattern also narrows the stereo effect zone and moves it away from the frontal plane of the speaker pair. The diameter of the diaphragm is equal to the diameter of the coil and there is no separate suspension for it. This sharply reduces the TNI of the GG, because The diffuser suspension is a very noticeable source of sound, and the material for the diaphragm can be very hard. However, the diaphragm is capable of producing sound well only at fairly high frequencies.

The coil and diffuser or diaphragm together with suspensions make up the moving system (MS) of the GG. The PS has a frequency of its own mechanical resonance Fр, at which the mobility of the PS sharply increases, and a quality factor Q. If Q>1, then a speaker without correctly selected and executed acoustic design (see below) at Fр will wheeze at a power less than the rated one, not to mention peak, this is the so-called. locking the GG. Blocking does not apply to distortion, because is a design and manufacturing defect. If 0.7

The efficiency of transferring electrical signal energy to sound waves in the air is determined by the instantaneous acceleration of the diffuser/diaphragm (who is familiar with mathematical analysis - the second derivative of its displacement with respect to time), because air is an easily compressible and very fluid medium. The instantaneous acceleration of the coil pushing/pulling the diffuser/diaphragm must be somewhat greater, otherwise it will not “swing” the IZ. A few, but not by much. Otherwise, the coil will bend and cause the emitter to vibrate, which will lead to the appearance of NI. This is the so-called membrane effect, in which longitudinal elastic waves propagate in the diffuser/diaphragm material. Simply put, the diffuser/diaphragm should “slow down” the coil a little. And here again there is a contradiction - the more the emitter “slows down”, the more powerfully it emits. In practice, the “braking” of the emitter is done in such a way that its NI in the entire range of frequencies and powers falls within the norm for a given Hi-Fi class.

Note, output: Don't try to "squeeze" out of the speakers what they can't do. For example, a speaker on a 10GDSH-1 can be built with an uneven frequency response in the midrange of 2 dB, but in terms of SOI and dynamics it still reaches Hi-Fi no higher than the initial one.

At frequencies up to Fp, the membrane effect never appears; this is the so-called. piston mode of operation of the GG - the diffuser/diaphragm simply moves back and forth. Higher in frequency, the heavy diffuser can no longer keep up with the coil, membrane radiation begins and intensifies. At a certain frequency, the speaker begins to radiate only like a flexible membrane: at the junction with the suspension, its diffuser is already motionless. At 0.7

The membrane effect dramatically improves the efficiency of the GG, because the instantaneous accelerations of vibrating sections of the IZ surface turn out to be very large. This circumstance is widely used by designers of high-frequency and partly mid-range generators, the distortion spectrum of which immediately goes into ultrasound, as well as when designing generators not for Hi-Fi. SOI GG with a membrane effect and the evenness of the frequency response of speakers with them strongly depend on the mode of the membrane. At zero mode, when the entire surface of the IZ trembles as if to its own rhythm, Hi-Fi up to medium inclusive can be achieved at low frequencies, see below.

Note: the frequency at which the GG switches from the “piston to the membrane”, as well as the change in the membrane mode (not growth, it is always an integer) significantly depend on the diameter of the diffuser. The larger it is, the lower in frequency and the stronger the speaker begins to “membrane”.

Woofers

High-quality piston LF GGs (simply “pistons”; in English woofers, barking) are made with a relatively small, thick, heavy and rigid anti-acoustic diffuser on a very soft latex suspension, see position 1 in Fig. Then Fр turns out to be below 40 Hz or even below 30-20 Hz, and Q

The periods of LF waves are long, all this time the diffuser in piston mode must move with acceleration, therefore the diffuser stroke is long. Low frequencies without acoustic design are not reproduced, but it is always closed to one degree or another, isolated from free space. Therefore, the diffuser has to work with a large mass of so-called. attached air, the “swing” of which requires significant force (which is why piston GGs are sometimes called compression), as well as for the accelerated movement of a heavy diffuser with a low quality factor. For these reasons, the magnetic system of the piston GG has to be made very powerful.



Despite all the tricks, the recoil of piston engines is small, because It is impossible for a low-frequency diffuser to develop high acceleration at long waves: the elasticity of the air is not enough to absorb the energy given off. It will spread to the sides, and the speaker will go into locking. To increase the efficiency and smoothness of the moving system (to reduce the SOI at high power levels), designers go to great lengths - they use differential magnetic systems, with half-scattering and other exotic ones. SOI is further reduced by filling the magnetic gap with a non-drying rheological fluid. As a result, the best modern “pistons” achieve a dynamic range of 92-95 dB, and the THD at nominal power does not exceed 0.25%, and at peak power – 1%. All this is very good, but the prices - mom, don't worry! $1000 per pair with differential magnets and rheofill for home acoustics selected for impact, resonant frequency and flexibility of the moving system is not the limit.

Note: LF GG with rheological filling of the magnetic gap are suitable only for LF links of 3-way speakers, because completely unable to operate in membrane mode.

Piston GGs have one more serious flaw: without strong acoustic damping, they can be mechanically destroyed. Again, simply: behind the piston speaker there must be some kind of air cushion loosely connected to the free space. Otherwise, the diffuser at the peak will be torn off the suspension and it will fly out along with the coil. Therefore, “pistons” cannot be installed in every acoustic design, see below. In addition, piston GGs do not tolerate forced braking of the PS: the coil burns out immediately. But this is already a rare case; speaker cones are usually not held by hand and matches are not inserted into the magnetic gap.

Note to craftsmen

There is a well-known “folk” way to increase the efficiency of piston engines: an additional ring magnet is firmly attached with the repelling side to the standard magnetic system from the rear, without changing anything in the dynamics. It is repelling, otherwise, when a signal is given, the coil will immediately be torn off from the diffuser. In principle, it is possible to rewind the speaker, but it is very difficult. And never before has a single speaker gotten better from rewinding, or at least remained the same.

But that’s not really what we’re talking about. Enthusiasts of this modification claim that the field of the external magnet concentrates the field of the standard one near the coil, which causes the acceleration of the PS and recoil to increase. This is true, but Hi-Fi GG is a very precisely balanced system. The returns actually increase a little. But at its peak, SOI immediately “jumps” so that sound distortions become clearly audible even to inexperienced listeners. At nominal, the sound may become even cleaner, but without Hi-Fi speakers it’s already high-fi.

Presenters

So in English (managers) they are called SCH GG, because. It is the midrange that accounts for the overwhelming majority of the semantic load of the musical opus. The requirements for the midrange of the GG for Hi-Fi are much softer, so most of them are made of a traditional design with a large diffuser cast from cellulose pulp along with the suspension, pos. 2. Reviews about midrange GG dome and with metal diffusers are contradictory. The tone prevails, they say, the sound is harsh. Classical lovers complain that bowed speakers squeal from “non-paper” speakers. Almost everyone recognizes the sound of the midrange GG with plastic diffusers as dull and at the same time harsh.

The stroke of the MF GG diffuser is made short, because its diameter is comparable to the wavelengths of the midrange and the transfer of energy into the air is not difficult. To increase the attenuation of elastic waves in the diffuser and, accordingly, reduce the NI together with the expansion of the dynamic range, finely chopped silk fibers are added to the mass for casting the Hi-Fi midrange GG diffuser, then the speaker operates in piston mode in almost the entire midrange range. As a result of applying these measures, the dynamics of modern midrange GGs of the average price level turns out to be no worse than 70 dB, and the THD at the nominal value is no higher than 1.5%, which is quite enough for high Hi-Fi in a city apartment.

Note: silk is added to the diffuser material of almost all good speakers, this universal method reduce the THD.

Tweets

In our opinion - tweeters. As you may have guessed, these are tweeters, HF GG. Spelled with one t, this is not the name of a social network for gossip. Making a good “tweeter” from modern materials would be generally simple (the LR spectrum immediately goes into ultrasound), if not for one circumstance - the diameter of the emitter in almost the entire HF range turns out to be of the same order of magnitude or less than the wavelength. Because of this, interference is possible at the emitter itself due to the propagation of elastic waves in it. In order not to give them a “hook” for radiation into the air at random, the diffuser/dome of the HF GG should be as smooth as possible; for this purpose, the domes are made of metallized plastic (it absorbs elastic waves better), and the metal domes are polished.

The criterion for choosing high-frequency GGs is indicated above: dome ones are universal, and for fans of the classics who definitely require “singing” soft tops, diffuser ones are more suitable. It is better to take these elliptical ones and place them in the speakers, orienting their long axis vertically. Then the speaker pattern in the horizontal plane will be wider, and the stereo area will be larger. There is also an HF GG with a built-in horn on sale. Their power can be taken at 0.15-0.2 of the power of the low-frequency section. As for the technical quality indicators, any HF GG is suitable for Hi-Fi of any level, as long as it is suitable in terms of power.

Shiriki

This is a colloquial nickname for broadband GG (GGSH), which does not require filtering of speaker frequency channels. A simple GGSH emitter with general excitation consists of a LF-MF diffuser and a HF cone rigidly connected to it, pos. 3. This is the so-called. coaxial emitter, which is why GGSH are also called coaxial speakers or simply coaxials.

The idea of ​​the GGSH is to give the membrane mode to the HF cone, where it will not do much harm, and let the diffuser at the LF and at the bottom of the midrange work “on a piston”, for which purpose the LF-MF diffuser is corrugated across. This is how broadband GGs are made for initial, sometimes mid-range Hi-Fi, for example. the mentioned 10GD-36K (10GDSH-1).

The first HF cone GGSH went on sale in the early 50s, but never achieved a dominant position in the market. The reason is a tendency to transient distortion and a delay in the attack of sound because the cone dangles and wobbles from the shocks of the diffuser. Listening to Miguel Ramos play a Hammond electric organ through a coaxial cone is unbearably painful.

Coaxial GGSH with separate excitation of LF-MF and HF emitters, pos. 4 do not have this drawback. In them, the HF section is driven by a separate coil from its own magnetic system. The HF coil sleeve passes through the LF-MF coil. The PS and magnetic systems are located coaxially, i.e. along one axis.

GGSH with separate excitation at LF are not inferior to piston GG in all technical parameters and subjective assessments of sound. Modern coaxial speakers can be used to build very compact speakers. The disadvantage is the price. A coaxial for high-end Hi-Fi is usually more expensive than a LF-MF + HF set, although it is cheaper than a LF, MF and HF GG for a 3-way speaker.

Auto

Car speakers are formally also classified as coaxial, but in reality they are 2-3 separate speakers in one housing. HF (sometimes also midrange) GG are suspended in front of the LF GG diffuser on a bracket, see on the right in Fig. at first. Filtering is always built-in, i.e. There are only 2 terminals on the body for connecting wires.

Car speakers have a specific task: first of all, to “shout out” the noise in the car’s interior, so their designers don’t particularly struggle with the membrane effect. But for the same reason, car speakers need a wide dynamic range, at least 70 dB, and their diffusers are necessarily made with silk or other measures are used to suppress higher membrane modes - the speaker should not wheeze even in a car while driving.

As a result, car speakers are, in principle, suitable for Hi-Fi up to medium, inclusive, if you choose a suitable acoustic design for them. In all the speakers described below, you can install auto speakers of a suitable size and power, then there will be no need for a cutout for the HF GG and filtering. One condition: the standard terminals with clamps must be very carefully removed and replaced with lamellas for unsoldering. Modern car speaker speakers allow you to listen to good jazz, rock, even individual works of symphonic music and many chamber music. Of course, they won’t be able to handle Mozart’s violin quartets, but very few people listen to such dynamic and meaningful opuses. A pair of car speakers will cost several times, up to 5 times, less than 2 sets of GG with filter components for a 2-way speaker.

Frisky

Friskers, from frisky, is how American radio amateurs nicknamed small-sized low-power GGs with a very thin and light diffuser, firstly, for their high output - a pair of “frisky” 2-3 W each sound a room of 20 square meters. m. Secondly – ​​for the hard sound: “fast” ones work only in membrane mode.

Manufacturers and sellers do not classify “frisky” people as a special class, because they are not supposed to be hi-fi. The speaker is like a speaker, like any Chinese radio or cheap computer speakers. However, for the “frisky” ones, you can make good speakers for your computer, providing Hi-Fi up to and including average in the vicinity of your desktop.

The fact is that the “fast” ones are capable of reproducing the entire audio range; you just need to reduce their SOI and smooth out the frequency response. The first is achieved by adding silk to the diffuser; here you need to be guided by the manufacturer and its (not trade!) specifications. For example, all GG of the Canadian company Edifier with silk. By the way, Edifier is a French word and is read “ediffier”, and not “idifier” in the English manner.

The frequency response of “fast” ones is equalized in two ways. Small splashes/dips are already removed by silk, and larger bumps and depressions are eliminated by acoustic design with free access to the atmosphere and a damping pre-chamber, see fig; For an example of such an AS, see below.



Acoustics

Why do you need acoustic design at all? At low frequencies, the dimensions of the sound emitter are very small compared to the length of the sound wave. If you simply place the speaker on the table, the waves from the front and rear surfaces of the diffuser will immediately converge in antiphase, cancel each other out, and no bass will be heard at all. This is called an acoustic short circuit. You cannot simply mute the speaker from the rear to the bass: the diffuser will have to strongly compress a small volume of air, which will cause the resonance frequency of the PS to “jump” so high that the speaker simply will not be able to reproduce bass. This implies the main task of any acoustic design: either to extinguish the radiation from the back side of the GG, or to turn it 180 degrees and re-radiate it in phase from the front of the speaker, while at the same time preventing the energy of the diffuser movement from being spent on thermodynamics, i.e. on the compression-expansion of air in the speaker housing. Additional task– if possible, form a spherical sound wave at the speaker output, because in this case, the stereo effect zone is widest and deepest, and the influence of room acoustics on the sound of the speakers is the least.

Note, important consequence: For each speaker enclosure of a specific volume with a specific acoustic design, there is an optimal range of excitation powers. If the power of the IZ is low, it will not pump up the acoustics; the sound will be dull and distorted, especially at low frequencies. An excessively powerful GG will go into thermodynamics, causing blocking to begin.

The purpose of the speaker cabinet with acoustic design is to ensure the best reproduction of low frequencies. Strength, stability, appearance- by itself. Acoustically, home speakers are designed in the form of a shield (speakers built into furniture and building structures), an open box, an open box with a panel acoustic impedance(PAS), closed box of normal or reduced volume (small-sized acoustic systems, MAS), bass reflex (FI), passive radiator(PI), direct and reverse horns, quarter-wave (QW) and half-wave (SW) labyrinths.

Built-in acoustics are a subject of special discussion. Open boxes from the era of tube radios; it is impossible to get acceptable stereo from them in an apartment. Among others, it is best for a beginner to choose the PV labyrinth for his first AS:

• Unlike others, except FI and PI, the PV labyrinth allows you to improve the bass at frequencies below the natural resonant frequency of the woofer speaker.
• Compared to FI PV, the labyrinth is structurally and simple to set up.
• Compared to PI PV, the labyrinth does not require expensive purchased additional components.
• The elbowed PV labyrinth (see below) creates a sufficient acoustic load for the GG, while at the same time having a free connection with the atmosphere, which makes it possible to use LF GG with both long and short diffuser strokes. Up to replacement in already built speakers. Of course, only a couple. The emitted wave in this case will be practically spherical.
• Unlike everything except a closed box and a HF labyrinth, an acoustic speaker with a MF labyrinth is capable of smoothing out the frequency response of the LF GG.
• Speakers with a PV labyrinth are structurally easily stretched into a tall, thin column, which makes them easier to place in small rooms.

Regarding the penultimate point - are you surprised if you are experienced? Consider this one of the promised revelations. And see below.

PV labyrinth

Acoustic design such as a deep slot (Deep Slot, a type of HF labyrinth), pos. 1 in Fig., and a convolutional inverse horn (item 2). We will touch on the horns later, but as for the deep slot, it is actually a PAS, an acoustic shutter that provides free communication with the atmosphere, but does not release sound: the depth of the slot is a quarter of the wavelength of its tuning frequency. This can be easily verified by using a highly directional microphone to measure the sound levels in front of the speaker and in the opening of the slit. Resonance at multiple frequencies is suppressed by lining the slot with a sound absorber. A speaker with a deep slot also dampens any speaker, but increases its resonant frequency, although less than a closed box.



The initial element of the PV labyrinth is an open half-wave tube, pos. 3. It is unsuitable as an acoustic design: while the wave from the rear reaches the front, its phase will flip another 180 degrees, and the same acoustic short circuit will result. In the frequency response of the PV pipe, it gives a high sharp peak, causing blocking of the GG at the tuning frequency Fn. But what is already important is that Fn and the frequency of the GG’s own resonance f (which is higher – Fр) are theoretically in no way related to each other, i.e. You can count on improved bass below f (Fр).

The simplest way to turn a pipe into a labyrinth is to bend it in half, pos. 4. This will not only phase the front with the rear, but also smooth out the resonant peak, because The wave paths in the pipe will now be of different lengths. In this way, in principle, you can smooth out the frequency response to any predetermined degree of evenness, increasing the number of bends (it should be odd), but in reality it is very rare to use more than 3 bends - wave attenuation in the pipe interferes.

In the chamber PV labyrinth (position 5), the knees are divided into the so-called. Helmholtz resonators - tapering towards the rear end of the cavity. This also improves the damping of the GG, smoothes the frequency response, reduces losses in the labyrinth and increases the radiation efficiency, because the rear exit window (port) of the labyrinth always works with “support” from the side of the last chamber. Having separated the chambers into intermediate resonators, pos. 6, it is possible with a diffuser GG to achieve an frequency response that almost satisfies the requirements of absolute Hi-Fi, but setting up each of a pair of such speakers requires about six months (!) of the work of an experienced specialist. Once upon a time, in a certain narrow circle, a labyrinth-chamber speaker with a separation of chambers was nicknamed Cremona, with a hint of the unique violins of Italian masters.

In fact, to obtain the frequency response for high Hi-Fi, just a couple of cameras per knee is enough. Drawings of speakers of this design are shown in Fig; on the left - Russian design, on the right - Spanish. Both are very good floor-standing acoustics. “For complete happiness,” it would not hurt the Russian woman to borrow the Spanish rigidity connections that support the partition (beech sticks with a diameter of 10 mm), and in return, smooth out the bend of the pipe.



In both of these speakers, another useful property of the chamber labyrinth is manifested: its acoustic length is greater than the geometric one, because the sound lingers somewhat in each chamber before passing on. Geometrically, these labyrinths are tuned to somewhere around 85 Hz, but measurements show 63 Hz. Realistic lower limit frequency range turns out to be 37-45 Hz depending on the type of low-frequency GG. If the filtered speakers from the S-30B are moved into such enclosures, the sound changes amazingly. For the better.



The excitation power range for these speakers is 20-80 W peak. Sound-absorbing lining here and there - padding polyester 5-10 mm. Tuning is not always necessary and is not difficult: if the bass is a bit muffled, cover the port symmetrically on both sides with pieces of foam until optimal sound is obtained. This should be done slowly, listening to the same section of the soundtrack each time for 10-15 minutes. It must have strong midranges with a steep attack (control of the midrange!), for example, a violin.

Jet Flow

The chamber labyrinth is successfully combined with the usual convoluted labyrinth. An example is the desktop acoustic system Jet Flow (jet flow) developed by American radio amateurs, which created a real sensation in the 70s, see fig. on right. The inside width of the case is 150-250 mm for speakers 120-220 mm, incl. “fast” and autodynamics. Body material – pine, spruce, MDF. No sound-absorbing lining or adjustment is required. The excitation power range is 5-30 W peak.

Note: There is now confusion with Jet Flow - inkjet sound emitters are sold under the same brand.

For the frisky and the computer

It is possible to smooth out the frequency response of car speakers and “fast” ones in an ordinary convoluted labyrinth by installing a compression damping (non-resonating!) pre-chamber in front of the entrance to it, designated K in Fig. below.



This mini-acoustic system is designed for PCs to replace the old cheap ones. The speakers used are the same, but the way they start to sound is simply amazing. If the diffuser is made of silk, otherwise there is no point in fencing the garden. An additional advantage is the cylindrical body, on which the midrange interference is close to minimal; it is less only on the spherical body. Working position – tilted forward and upward (AC – sound spotlight). Excitation power – 0.6-3 W nominal. Assembly is carried out as follows. order (glue - PVA):

• For children 9 glue the dust filter (you can use scraps of nylon tights);
• Det. 8 and 9 are covered with padding polyester (indicated in yellow in the figure);
• Assemble the package of partitions using screeds and spacers;
• Glue in padding polyester rings, marked in green;
• The package is wrapped, gluing, with whatman paper until the wall thickness is 8 mm;
• The body is cut to size and the antechamber is pasted over (highlighted in red);
• They glue the children. 3;
• After complete drying, they sand, paint, attach a stand, and mount the speaker. The wires to it run along the bends of the labyrinth.

About horns

Horn speakers have high output (remember why they have a horn in the first place). The old 10GDSH-1 screams through its horn so loudly that your ears wither, and the neighbors “can’t be happier,” which is why many people get carried away with horns. In home speakers, curled horns are used as they are less bulky. The reverse horn is excited by the back radiation of the GG and is similar to the PV labyrinth in that it rotates the phase of the wave by 180 degrees. But otherwise:

1. Structurally and technologically it is much more complicated, see fig. below.
2. It does not improve, but on the contrary, it spoils the frequency response of the speakers, because The frequency response of any horn is uneven and the horn is not a resonating system, i.e. It is impossible in principle to correct its frequency response.
3. The radiation from the horn port is significantly directional, and its waveform is more flat than spherical, so one cannot expect a good stereo effect.
4. It does not create a significant acoustic load on the GG and at the same time requires significant power for excitation (let’s also remember whether they whisper into a speaking speaker). Dynamic range horn speakers can be stretched, at best, to basic Hi-Fi, and in piston speakers with a very soft suspension (which means good and expensive ones), the diffuser breaks out very often when the GG is installed in the horn.
5. Gives more overtones than any other type of acoustic design.



Frame

The housing for the speakers is best assembled using beech dowels and PVA glue; its film retains its damping properties for many years. To assemble, one of the side panels is placed on the floor, the bottom, lid, front and back walls, partitions are placed, see fig. on the right, and cover with the other side. If the external surfaces are subject to final finishing, you can use steel fasteners, but always with gluing and sealing (plasticine, silicone) of non-adhesive seams.



The choice of housing material is much more important for sound quality. The ideal option is a musical spruce without knots (they are a source of overtones), but finding large boards of it for speakers is unrealistic, since spruce trees are very knotty trees. As for the plastic speaker enclosures, they only sound good if they are manufactured in one piece, while amateur home-made ones made of transparent polycarbonate, etc. are a means of self-expression, not acoustics. They will tell you that this sounds good - ask to turn it on, listen and believe your ears.

In general, natural wood materials for speakers are difficult: completely straight-grained pine without defects is expensive, and other available building and furniture species produce overtones. It is best to use MDF. The above-mentioned Edifier has long since completely switched to it. The suitability of any other tree for AS can be determined by following. way:

1. The test is carried out in a quiet room, in which you yourself need to first stay in silence for half an hour;
2. A piece of board approx. long. 0.5 m is placed on prisms made from sections of steel angles, laid at a distance of 40-45 cm from each other;
3. The knuckle of a bent finger is used to knock approx. 10 cm from any of the prisms;
4. Repeat tapping exactly in the center of the board.

If in both cases the slightest ringing is not heard, the material is suitable. The softer, duller and shorter the sound, the better. Based on the results of such a test, you can make good speakers even from chipboard or laminate, see the video below:

Video: a simple do-it-yourself laminate speaker for your phone

Spikes

Floor-standing and tabletop speakers are installed on special legs - acoustic spikes - which prevent the exchange of vibrations between the speakers and the floor or tabletop. Acoustic spikes are available for sale, but the prices are, you know, a special product. So, weights for construction and carpentry plumb lines have exactly the same configuration (a cylinder turning into a cone with a rounded nose) and material properties. Price - you understand. Feel free to place any speakers on spikes made of plumb weights; they will cope with an unusual task for them perfectly.