Making a mini speaker with an amplifier. Creation of columns in the text editor Microsoft Word Acoustic device creation technology

I want to submit my project, so to speak home audio system. At the beginning of my knowledge of acoustics, there was generally zero, I didn’t even know how to assemble ordinary class A amplifiers, let alone amplifiers for a subwoofer. Interest arose after an even more “green” radio electronics engineer came to me and offered to make a subwoofer. I didn’t want to seem like a layman and climbed into Googledia to find something there on this topic, but either I googled badly, or it’s real useful information I didn’t, in general I didn’t dig up anything sensible, I climbed to smoke forums, scooped up information there and got down to business. First of all, we need a low-frequency speaker, I immediately warn you, our subwoofer is low-budget and not very powerful, I found only 35gdn-1m-4 in my store, it looks like this:

Also known under the secret Soviet code name 25gdn-1-4. Why two identical speakers are called differently, I don’t know, you need to ask the scoops, because I don’t know what was going on in their heads when they came up with it. Its characteristics are as follows:

• Main resonance frequency: 80 (100) Hz;
• Frequency band: 63-5000Hz;
• Frequency response flatness: 14 dB;
• Intrinsic Sensitivity Level: 83 dB/m W;
• Dimensions (in plan): 125x125 mm;
• Height: 75.5mm;
• Equivalent volume: 11 dm;
• Full quality factor: 0.55;
• Weight: 1.3 kg.

He has a passport power of 25 watts, but the scoops generally had their own concept of power, because he yells at all 60. Now let's deal with the box for him. There were many ideas and proposals about which I knew nothing at all, well, for example, who knew what close box is it just a speaker in a sealed box?

1. closed box(ZYa, closed box). The simplest case in design and manufacture. Widely used acoustic design. It is a sealed box. The radiation from the back of the speaker cone is closed in the housing and, in fact, is not used. All energy is then converted into heat. Often, in order to combat this, padding is used in SL various materials synthetic winterizer, wool, mineral wool etc. A significant disadvantage is the extremely low efficiency, since only one side of the speaker emits sound. To get a big sound pressure this case requires powerful speakers. The main advantage this design is an best quality sound. The bass of the subwoofer in a closed cabinet is soft, clear and fast. EBP 40-60

2. The main principles of the operation of the phase inverter housing- to make the radiation of the rear part of the diffuser work to the benefit. To do this, the internal volume of the body is connected to the atmosphere using pipes or slots. A port (pipe or slot), contrary to popular belief, does not create a "draft" or "blowing".

The principle of operation is somewhat different. The port contains a certain amount of air. Together with the air contained in the box, as well as the movable speaker system, this creates an oscillatory system, the oscillations of which coincide in phase with the oscillations of the cone. In other words, we make the radiation from the back of the diffuser work for our benefit, adding up with the radiation from the front.

Thus, the efficiency of the system, in fact, doubles. Setting up a bass-reflex housing, both by selecting the volume, and by using the area and length of the port. The downside of this design is the lower sound quality compared to the SL. The bass is more smeared and booming. To increase the sound quality, many tricks are used in the design, such as the use of a port without turns, a port design in the form of a prism, rounded ends of the port, and so on. EBP > 50

3. Passive radiator(passive radiator, passive radiator). The principle of operation of this design is the same as that of a phase inverter. The difference is that instead of the volume of air in the phase inverter port, a passive radiator is used, which is a speaker without a magnet and a voice coil. The advantage of this design is a better sound, since the passive radiator does not introduce distortion, unlike a phase inverter. from EBP > 50

4. Bandpass(bandpass, bandpass) 4 orders - Body divided into two parts internal partition. One part is a closed volume of air like in a closed box. The second part communicates with the atmosphere through the port. Due to the concentration of radiation in a narrow frequency band, it has a higher efficiency than a phase inverter, with a higher sound quality. EBP 40-60

As you have already noticed, the complexity in the manufacture of the case is growing according to the principle: further more. Since a carpenter from me, frankly, a bad one, I chose the simplest option - a closed box, for which I received a lyuley from my father, who said that, they say, phase inverters rule and sent for it.

Basically a phase inverter the best way for this, the dynamics, as I later realized because of the resonant structures and other incomprehensible riff-raff, didn’t go into details, and I don’t advise you either, because the forest is impenetrable there, and I can get lost in three pines anyway. Then there was a problem with the dimensions of the case, I went back to Google and again I didn’t find anything, then I read somewhere that the larger the case, the better, and climbed into the workshop to make a miracle out of plywood. Why plywood and not chipboard? Chipboard, after all, is sawn better. I was really too lazy to stomp 200 meters behind her, and, to be honest, I squeezed the money. The dimensions of the box are as follows:

Drawn in Paint, the dimensions are taken from heaven, but it turned out to be about 40-50 liters, which is generally the salt for this speaker. The phase inverter is sewage pipe glued on mounting glue and reinforced with two planks. Its diameter is 5 cm and its length is 15 cm.

As soon as the box was put together, not literally put together, it is better to fasten it through the aluminum corners, otherwise there will be many cracks and the bass will be bad. Then we buy a sealant, not a silicone one, we don’t smear a bath, but an ordinary mounting one, white color. And in places of joints and cracks we seal everything. On the sealant, they usually write how much it dries, but who knows how it gets. Next, we take the back wall of the box and fit the dimensions of the terminal block that you buy, by the way it looks like this:

We cut a hole, insert the terminal block, fix it with self-tapping screws, seal it. After everything is dry, you need to insert the speaker and fix it on the screws, then seal it in the same way, and wait until it dries. Then we connect the terminal block and the speaker with wires, preferably with solder. So that later it was not torn off. In the front wall below the speaker, we cut a hole along the phase inverter (pipe). We insert, fasten with glue, and two planks across them are also glued:

Again, we seal everything and everything so that it does not blow through. We are waiting for it to dry. Having finished torturing the plywood, I propose to close the back cover with a pair, another with self-tapping screws, and go through the joints with plenty of sealant, because remember: cracks = garbage, not a subwoofer. Finally, we can proceed to the amplifier. I propose to assemble it on tda2051, it gives good power, and for state employees it has a unipolar switching on of the circuit in order to use a conventional power supply. Here is the circuit itself, do not pay attention to what is written on the tda2050 circuit at all, the circuits for switching on amplifiers like tda20xx are all the same and differ only in output power. It's just that tda2051 yells more powerfully.

I just want to warn you right away, put the microcircuit on the radiator, and the larger it is, the better and safer, the legs of the microcircuits - amplifiers are kept on an honest Chinese word and it is not recommended to pull them, they will fall off - do not insert back, but it costs 150r plus you will have to follow it also go, you buy them at once 2 pieces, so, just in case a fireman. Electrolytes use 36 volts, also for safety. Replace C1 with 100 nF, 2.2 microfarads seemed a bit too much to me. There is nothing to force the entrance, for nutrition I advise you to put electrolytes of a larger capacity and larger sizes, otherwise there may be a background from the block.

In general, the P-filter would be very good here in order to reduce all the hums. The case for the amplifier was taken from an old CD drive, which bears the proud name of Pioneer. Holes are cut at the back for the audio input, power supply and two wires leading to the terminal block.

By the way, for aesthetics, you can upholster the subwoofer with a drape, as I actually did. Drap additionally muffles the sound, which increases the quality factor. The whole thing is powered by a power supply from a charger for a screwdriver and has a voltage of 21.7 volts, of course it’s not so hot, give it free rein they will eat 35 and won’t choke, it will work even better, but don’t get carried away, remember that amplifier chips are capricious guys , and they can make broads, well, or just burn out.

I don’t advise you to paint the speaker with bologna paint, I personally started eating a rubber suspension, which became thinner and ate it, I had to change the suspension, thanks to the narrow-eyed brothers for the paint, which included at least half of the periodic table. I wish you success in the assembly, your S9018.

Word text editor allows you to format text with the most different ways. Latest Versions this program has become so overgrown with various functions that now there is practically nothing that this program cannot do. text editor. In this article, we will talk about how to make text in two columns in Word.

Correct way to make text in two columns in Word

In order to make text in two columns in Word, you need to go to the tab " Page layout"and click on the" Speakers". After that, a drop-down menu will appear where you can select the number of columns you want to place on this page.

The following options are available in this drop-down menu:

• one - one column, the usual page format in Word;
• two - two identical columns, a page with two columns;
• three - three identical columns, a page with three columns;
• on the left - a narrow additional column on the left side of the page;
• on the right - a narrow additional column on the right side of the page;

In addition, in the drop-down menu there is an item " Other columns". This item opens additional window, in which you can adjust the width of the columns and the spacing between them.

Also, the size of the columns can be set using the ruler, which is located above the page.

Wrong way to make text in two columns in Word

The second way to create columns in Word can be considered wrong, but it is often more convenient. For this method, tables with invisible borders are used. Go to the Insert tab and use the Table button to create a table with two columns.

After the table is created, place the cursor inside the table and go to the tab " Working with tables - Constructor". Here you need to change the type of line that is used to draw the borders of the table. To do this, open the drop-down menu and select " Without border".

Such a line is visible while editing the document, but does not appear when it is printed.

How to make text two columns in Word 2003

If you are using Word 2003, then in order to make the text in two columns you need to open the menu " Format - Columns". After that, the "Columns" window will appear.

In this window, you need to select the number of columns and click on the " OK». If necessary, you can adjust the width of the columns, the spaces between them, as well as other parameters.

The Word text editor from Microsoft, which is included in the Office software package, has long become the unspoken standard for users for everything related to typing, layout and printing of text information. This program contains almost everything that may be needed in the process of creating text documents. Such rich functionality often turns into the fact that many users do not know or forget how to use this or that function.

Very often there are difficulties with such a simple action as dividing text in Word into 2 or more columns. Therefore, this article will remind or tell you how to split text in Word into 2 columns in different versions of the program.

In order to split text into 2 columns in Word, follow these steps.
In some cases, when you are not satisfied with the automatic division of text into columns, it is more convenient to use tables to divide the page into columns. To do this, create a table by selecting Insert –> Table in the menu and setting the table format as 2x1(two columns with one row).

After that, spread the text across the table cells that will become your columns, and make the table borders invisible by placing the cursor inside any cell and selecting the setting Borders –> no border in table editing mode.

In today's acoustics market, there are many sound systems- they can be of different types, power and design, you can choose speakers for every taste and for any needs. However, purchased columns are not always 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 your own, the speakers will even sound subjectively better.

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

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

If you are sure that you are ready to assemble the speakers yourself, you need to prepare the tools and materials, and you can proceed. Leaving aside the question of what type of final acoustic system- it does not matter, general principles the builds are the same whether you build small front speakers or a huge and powerful 5.1 system. In principle, only the scope 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 and in what form they can be made of. First of all, you should find out what the column body can be.

The quality of the cabinet plays a huge role in giving the sound clarity 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 deaf) to the complete inoperability of the speaker. Do not worry ahead of time - just having calculated everything, everything will turn out at 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 in working with a tree, a decimeter of error is not an error, so minor errors are quite forgivable.

The first thing to choose is the shape of future columns. It can be almost anything, but for independent work it is best to choose the traditional rectangular shape. If it is planned to manufacture not a broadband speaker, but a subwoofer, then the shape should be cubic. Please also note that the manufacture of a subwoofer requires maximum accurate calculations the volume of the column, as well as the phase inverter, otherwise the bass will not be reproduced with sufficient quality, which will nullify the meaning of the work.

Column sizes can also be different. If a large set of speakers is to be used - up to three mid-ranges, one high-frequency tweeter and a low-frequency subwoofer - the speaker should, of course, be high. 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 very precise calculations do not make much sense if you do not have ears capable of picking up the slightest deviations in the amplitude of the sound from a perfectly straight line. So it is enough to roughly calculate the required volume, based on the diameter and power of the dynamic emitter. If the speaker is multi-band, the subwoofer is taken as the basis.

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

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

Medium density particle board, or MDF, works best. Solid wood is not suitable for the reason that 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 imperceptible to the naked eye always occur in it, due to which unpressed wood dries out relatively quickly and becomes unusable. One of the few types of wood that can be used to make a DIY column is ebony, or ebony, which is the hardest of all woods and also polishes perfectly. However, ebony is very expensive, so in most cases it will not work - after all, one of the goals of independent work is profitability.

Another possible variant material - multilayer plywood. It is easy to process, and after assembling the case, it can be finished with any decor - for example, natural veneer. Its only drawback is not the highest rigidity, so for greater structural strength, you will have to additionally cut out the 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 performance, which allows you to save some money on protective material. However, they have a high mass and are 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 - it is better in terms of properties and looks good, imitating almost any material - for example, the same ebony.

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

• Flat frequency response - this parameter reflects the sound quality, since it represents the difference between the received electrical signal and the output sound waves. It is to obtain the ideal frequency response that all efforts should be directed in the manufacture of a home-made column. The quality of the frequency response is influenced by many factors - this is the correct location of the speaker parts inside the case, and the quality of the materials used, and even the environment.
• Decent efficiency. Since in dynamics the electrical signal is converted into mechanical movements diffuser - vibrations of its membrane, which create sound - the efficiency is always very low. We must try to raise it as high as possible. Can help with this correct selection details.
• Subjective sound quality - the speaker should be pleasant to listen to, because it will not be used by a device for measuring sound characteristics, but by 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 an approximate design of the column, you can begin to manufacture the column with your own hands.

Technology for creating an acoustic device

One of the main principles that must be followed when working is accuracy. It is necessary to make all measurements as carefully as possible before proceeding with cutting out the parts, and before fastening them, everything must be tried on to each other.

The steps for making a column are:

1. On harvested chipboard sheets the walls of the future building are drawn. On the walls, you need to mark the places for installing the speakers - the holes should be round and ideally fit the size of the emitters, so that in the end there are no gaps.
2. 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 just twist with screws. In the first case, you need to do everything very carefully so that the column does not warp. To press the parts smeared with glue to each other, you can use the vise system. It is also necessary to fasten the walls with thin screws carefully so that they enter at a perfectly right angle.
4. The case must be airtight, therefore, if the wall joints are not tight enough, the gaps must be filled with felt impregnated with glue. If the back panel is removable, a polymer or rubber seal must be glued along its edge.
5. If the box is closed, instead of upholstering the walls with soundproofing, cotton wool or foam rubber can be filled right up, filling the entire volume of the column with it. The main thing is that it does not come into contact with rear surface diffuser. In addition, a channel must be formed from the emitter to the phase inverter.
6. It is not necessary to calculate the length of the phase inverter - it is perfectly selected empirically. The diameter is easy to calculate - for example, a pipe 5 cm wide is perfect for a speaker with a diameter of more than 100 mm. The length is determined as follows - two home-made cardboard tubes are taken and inserted into each other, and then placed in a hole designed for a phase inverter. 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 the most active.
7. When the case is assembled, all that remains is to place the speakers and amplifier in it. Emitters are connected either in series or in parallel, depending on the required characteristics of the column.

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

Creating columns with your own hands: video

To make sound speakers with your own hands - with this, for many, the hobby begins to be difficult, but very interesting business- sound reproduction technique. Economic considerations often become the initial motivation: the prices for branded electro-acoustics are overstated, not excessively - ugly arrogantly. If the sworn audiophiles, who do not skimp on rare tubes for amplifiers and flat silver wire for winding audio transformers, complain on the forums that the prices for acoustics and speakers for it are systematically inflated, then the problem is really serious. Do you want speakers for the house for 1 million rubles. pair? Please, there are more expensive ones. So The materials in this article are designed primarily for the very, very beginners: they need to quickly, simply and inexpensively make sure that the creation of their own hands, for which everything took dozens of times less money than for a “cool” brand, can “sing” no worse, or at least comparable. But probably, some of the foregoing will be a revelation for the masters of amateur electroacoustics- if it is honored by reading them.

Speaker or speaker?

Sound column (KZ, sound column) is one of the types of acoustic design of electrodynamic loudspeaker heads (GG, speakers), designed for technical and information sounding of large public spaces. In general, the acoustic system (AS) consists of a primary sound emitter (FROM) and its acoustic design, which provides the required sound quality. Home speakers are for the most part similar in appearance to loudspeakers, which is why they are nicknamed. Electroacoustic systems (EAS) also include an electrical part: wires, terminals, crossover filters, built-in audio frequency power amplifiers (UMZCH, in active speakers), computing devices (in speakers with digital channel filtering), etc. Acoustic design of household speakers is usually located in the body, which is why they look like more or less elongated columns.

Acoustics and electronics

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

The remainder of the article focuses primarily on how to make speakers that provide good acoustics. The electronic part of electroacoustics is a subject of special serious discussion, and not just one. Here it should only be noted that, firstly, at first it is not necessary to take on digital filtering that is close to ideal, but complex and expensive, but to apply passive filtering on inductive-capacitive filters. For a 2-way speaker, you need only one plug of low-pass/high-pass crossover filters (LPF/HPF).

For the calculation of separation ladder AC filters, there is special programs, eg. JBL Speaker Shop. However, at home, the individual tuning of each plug for a specific instance of the speakers, firstly, does not hit production costs in mass production. Secondly, the replacement of the GG in the AU is required only in exceptional cases. This means that the filtering of the AC frequency channels can be approached unconventionally:

1. The frequency of the section LF-MF m HF is taken not lower than 6 kHz, otherwise you will not get a sufficiently uniform amplitude-frequency characteristic (AFC) of the entire speaker in the midrange region, which is very bad, see below. In addition, at a high crossover frequency, the filter is inexpensive and compact;
2. The prototypes for calculating the filter are links and half links of filters of type K, because their phase-frequency characteristics (PFC) are absolutely linear. Without observing this condition, the frequency response in the region of the crossover frequency will turn out to be significantly uneven and overtones will appear in the sound;
3. To obtain the initial data for the calculation, it is necessary to measure the impedance (impedance) of the LF-MF and HF GG at the crossover frequency. The GG 4 or 8 Ohms indicated in the passport are their active resistance to DC, and the impedance at the crossover frequency will be larger. The impedance is measured quite simply: the GG is connected to an audio frequency generator (GZCH), tuned to the crossover frequency, with an output of at least 10 V to a load of 600 Ohms through a resistor of obviously high resistance, for example. 1 kOhm You can use low-power GZCH and UMZCH high fidelity. The impedance is determined by the ratio of the audio frequency (AF) voltages across the resistor and GG;
4. The impedance of the LF-MF link (GG, heads) is taken as the characteristic impedance ρn of the low-pass filter (LPF), and the impedance of the HF head is taken as ρv of the high-pass filter (HPF). The fact that they are different - well, the fool is with them, the output impedance of the UMZCH, "rocking" the speakers, is negligible compared to this and that;
5. From the side of the UMZCH, reflective-type low-pass and high-pass filters are installed so as not to overload the amplifier and not take power from the associated speaker channel. To GG, on the contrary, they turn to absorbing links, that the return from the filter did not give overtones. Thus, low-pass and high-pass speakers will have at least a link with a half link;
6. The attenuation of the LPF and HPF at the crossover frequency is taken equal to 3 dB (1.41 times), because the steepness of the slopes of K-filters is small and uniform. Not 6 dB, as it may seem, because. filters are calculated by voltage, and the power supplied to the GG depends on it squarely;
7. Adjusting the filter comes down to "muting" a too loud channel. The loudness of the channels at the crossover frequency is measured using a computer microphone, turning off HF and LF-MF in turn. The degree of "muting" is defined as the square root of the ratio of the loudness of the channels;
8. The excessive volume of the channel is removed with a pair of resistors: quenching by fractions or units of ohms is connected in series with the GG, and in parallel with both of them - an equalizing greater resistance so that the impedance of the GG with the resistors remains unchanged.

Explanations to the methodology

A technically knowledgeable reader may have a question: does the filter for the complex load work for you? Yes, and in this case- that's all right. The phase response of K-filters is linear, as mentioned, and Hi-Fi UMZCH is almost an ideal voltage source: its output impedance Rout is units and tens of mΩ. Under such conditions, the “reflection” from the HG reactance will partially attenuate in the output absorbing link/filter half link, but for the most part will seep back to the UMZCH exit, where it will disappear without a trace. In fact, nothing will pass into the associated channel, because ρ of its filter is many times greater than Rout. There is one danger here: if the impedance of the GG and ρ are different, then power circulation will begin in the filter output - GG circuit, which will make the bass become dull, “flat”, attacks on the midrange will be prolonged, and the top will be sharp, with a whistle. Therefore, the impedance of the GG and ρ must be adjusted exactly, and in the event of a replacement of the GG, the channel will have to be tuned again.

Note: do not try to filter active speakers with analog active filters on operational amplifiers (op-amps). It is impossible to achieve the linearity of their phase characteristics in a wide frequency range, therefore, for example, analog active filters have not really taken root in telecommunication technology.

What is hifi

Hi-Fi, as you know, is short for High Fidelity - high fidelity (sound reproduction). The concept of Hi-Fi was initially accepted as vague and not subject to standardization, but its informal division into classes gradually developed; the numbers in the list indicate, respectively, the range of reproducible frequencies (operating range), the maximum allowable coefficient of non-linear distortion (THD) at rated power (see below), the minimum allowable dynamic range relative to the room's own noise (dynamics, the ratio of the maximum volume to the minimum), the maximum allowable frequency response unevenness in the midrange and its blockage (decline) at the edges of the operating range:

• Absolute or full - 20-20,000 Hz, 0.03% (-70 dB), 90 dB (31,600 times), 1 dB (1.12 times), 2 dB (1.25 times).
• High or heavy - 31.5-18,000 Hz, 0.1% (-60 dB), 75 dB (5600 times), 2 dB, 3 dB (1.41 times).
• Medium or basic - 40-16,000 Hz, 0.3% (-50 dB), 66 dB (2000 times), 3 dB, 6 dB (2 times).
• Initial - 63-12500 Hz, 1% (-40 dB), 60 dB (1000 times), 6 dB, 12 dB (4 times).

It is curious that high, basic and initial Hi-Fi approximately correspond to the highest, first and second classes of household electroacoustics according to the USSR system. The concept of absolute Hi-Fi arose with the advent of condenser, film-panel (isodynamic and electrostatic), jet and plasma sound emitters. Heavy (Heavy) high Hi-Fi called the Anglo-Saxons, because. High High Fidelity in English is like butter.

What kind of hi-fi do you need?

Home acoustics for modern apartment or houses with good soundproofing must satisfy the conditions for basic Hi-Fi. High there, of course, will not sound worse, but it will cost a lot more. In block Khrushchev or Brezhnevka, no matter how you isolate them, only professional experts distinguish between initial and basic Hi-Fi. The grounds for such a coarsening of the requirements for home acoustics are as follows.

Firstly, the full range of sound frequencies is heard by literally a few people from all over humanity. People gifted with a particularly delicate ear for music, such as Mozart, Tchaikovsky, J. Gershwin, hear high Hi-Fi. Experienced professional musicians in a concert hall confidently perceive basic Hi-Fi, and 98% of ordinary listeners in a sound chamber almost never distinguish between initial and basic in frequency.

Secondly, in the most audible region of the midrange, a person in terms of dynamics distinguishes sounds in the range of 140 dB, counting from the audibility threshold of 0 dB, equal to the intensity of the sound flux of 1 pW per square meter. m, see fig. curves of equal loudness on the right. A sound louder than 140 dB is already pain, and then - damage to the hearing organs and concussion. An expanded symphony orchestra on the most powerful fortissimo produces sound dynamics up to 90 dB, and in the halls of the Grand Opera, Milan, Paris, Vienna Opera Houses and the Metropolitan Opera in New York, it is able to “accelerate” up to 110 dB; such is the dynamic range of leading jazz bands with symphonic accompaniment. This is the limit of perception, louder than which the sound turns into still tolerable, but already meaningless noise.

Note: rock bands can play louder than 140 dB, which Elton John, Freddie Mercury and the Rolling Stones were fond of when they were young. But the dynamics of rock does not exceed 85 dB, because rock musicians cannot play the most delicate pianissimo with all their desire - the equipment does not allow, and there is no rock "in spirit". As for pop music of any kind and movie soundtracks, this is not a topic at all - their dynamic range is already compressed to 66, 60 and even 44 dB during recording, so that you can listen to anything.

Thirdly, natural noises in the quietest living room country house behind the backyards of civilization - 20-26 dB. Sanitary noise standard in reading room libraries - 32 dB, and the rustle of leaves in the fresh wind - 40-45 dB. From this it is clear that the high Hi-Fi speakers of 75 dB are more than enough for meaningful listening in living conditions; the dynamics of modern UMZCH of the average level, as a rule, is not worse than 80 dB. In a city apartment, it is almost impossible to recognize basic and high Hi-Fi by the dynamics.

Note: in a room noisier than 26 dB, the frequency range of your favorite Hi-Fi can be narrowed down to the limit. class, because the effect of masking affects - against the background of indistinct noises, the sensitivity of the ear in frequency decreases.

But in order for Hi-Fi to be high-fi, and not “happiness” for “beloved” neighbors and harm to the health of the owner, it is necessary to ensure even the smallest possible sound distortion, correct reproduction of low frequencies, smooth frequency response in the midrange region, and determine what is necessary for scoring this room AC electric power. As a rule, there are no problems with HF, because. their SOI "leave" in the inaudible ultrasonic region; you just need to put a good HF head in the speakers. It is enough to note here that if you prefer classics and jazz, it is better to take the HF GG with a cone for a power of 0.2-0.3 from that of the low-frequency channel, for example. 3GDV-1-8 (2GD-36 in the old way) and the like. If you are “rushing” from hard tops, then the HF GG with a dome emitter (see below) with a power of 0.3-0.5 of the power of the low-frequency link will be optimal; drumming with brushes is naturally reproduced only by dome tweeters. However, a good dome tweeter is suitable for any kind of music.

distortion

Sound distortions are possible linear (LI) and non-linear (NI). Linear distortion is, simply, a discrepancy between the average volume level and the listening conditions, for which any UMZCH has a volume control. In expensive 3-way speakers for high Hi-Fi (for example, the Soviet AC-30, aka S-90), power attenuators for midrange and treble are often introduced in order to more accurately adjust the frequency response of the speaker to the acoustics of the room.

As for NI, they, as they say, are innumerable and new ones are constantly being discovered. The presence of NI in the audio path is expressed in the fact that the shape of the output signal (which the sound is already in the air) is not completely identical to the shape of the original signal from the primary source. Most of all they spoil the purity, "transparency" and "juiciness" of the sound of the trace. NI:

1. Harmonic - overtones (harmonics) that are multiples of the fundamental frequency of the reproduced sound. Manifested as excessively roaring bass, sharp and hard midrange and treble;
2. Intermodulation (combination) - the sums and differences of the frequencies of the components of the spectrum of the original signal. Strong combinational NIs are heard as wheezing, and weak, but spoiling the sound, can only be recognized in the laboratory by multi-signal or statistical methods on test phonograms. By ear, the sound seems to be clear, but somehow not so;
3. Transient - "jitter" of the output signal form with sharp rises / falls of the original. They manifest themselves with short wheezing and sobbing, but irregularly, at volume jumps;
4. Resonant (overtones) - ringing, rattling, mumbling;
5. Frontal (distortion of the sound attack) - delaying or, conversely, forcing sharp changes in the overall volume. Almost always occur together with transitional;
6. Noise - hum, rustle, hiss;
7. Irregular (sporadic) - clicks, cods;
8. Interference (AI or IFI, not to be confused with intermodulation). They are characteristic specifically for the AU, in the UMZCH IFI do not occur. Very harmful, because. perfectly audible and unremovable without a major alteration of the speakers. See below for more information on FFI.

Note:"wheezing" and other figurative descriptions of distortion hereinafter are given from the point of view of Hi-Fi, i.e. as already heard by sophisticated listeners. And, for example, speech speakers are designed for SOI at a nominal power of 6% (in China - by 10%) and 1

In addition to interference, speakers can give predominantly NI according to paragraphs. 1, 3, 4 and 5; clicks and cods are possible here as a result of poor-quality workmanship. They fight with transient and frontal NIs in speakers by selecting suitable HGs (see below) and acoustic design for them. Ways to avoid overtones - the rational design of the speaker cabinet and the right choice of material for it, also see below.

It is necessary to linger on harmonic NI in the AC, because they are fundamentally different from those in semiconductor UMZCH and are similar to the harmonic NI tube ULF (low-frequency amplifiers, the old name is UMZCH). A transistor is a quantum device, and its transfer characteristics are not fundamentally expressed by analytical functions. The consequence is that it is impossible to accurately calculate all the harmonics of the transistor UMZCH, and their spectrum stretches to the 15th and higher components. Also, in the spectrum of transistor UMZCH, the proportion of combinational components is large.

The only way to deal with all this mess is to hide the NI deeper under the amplifier's own noise, which, in turn, should be many times lower than the natural noise of the room. I must say that modern circuitry copes with this task quite successfully: according to the current ideas, UMZCH with 1% THD and -66 dB of noise is “no”, and with 0.06% THD and -80 dB of noise is pretty mediocre.

With harmonic NI speaker speakers, the situation is different. Their spectrum, firstly, like that of tube ULFs, is pure - only overtones without a noticeable admixture of combination frequencies. Secondly, the AC harmonics can be traced, just like in lamps, not higher than the 4th. Such an NI spectrum does not noticeably spoil the sound even with a SOI of 0.5-1%, which is confirmed by expert estimates, and the reason for the “dirty” and “sluggish” sound of home-made speakers lies most often in the poor frequency response in the midrange. For your information, if the trumpeter did not properly clean the instrument before the concert and during the game does not splash saliva out of the embouchure in a timely manner, then the THD of, say, a trombone can grow up to 2-3%. And nothing, they play, the audience likes it.

The conclusion from here follows a very important and favorable one: the frequency range and intrinsic harmonics of the NI speakers are not parameters that are critical for the quality of the sound it creates. The sound of speakers with 1% and even 1.5% harmonic NI experts can be attributed to the basic, and even high Hi-Fi, if appropriate. conditions for the dynamics and smoothness of the frequency response.

Interference

IFI is the result of the convergence of sound waves from nearby sources in phase or in antiphase. The result is bursts, up to pain in the ears, or dips of almost zero volume at certain frequencies. At one time, the first-born of the Soviet Hi-Fi 10MAC-1 (not 1M!) Was urgently discontinued after the musicians discovered that this speaker did not reproduce the second octave at all (as far as I remember). At the factory, the prototype was “chased” in a sound meter using the three-signal method, antediluvian even then, and there was no position of an expert with an ear for music in the staffing table. One of the paradoxes of developed socialism.

The probability of occurrence of IFI increases sharply with an increase in frequency and, accordingly, a decrease in the wavelength of sound, since for this, the distance between the centers of the emitters must be a multiple of half the wavelength of the reproducible frequency. On MF and HF, the latter changes from units of decimeters to millimeters, therefore, it is impossible to put two or several MF and HF GGs in the AU - then you cannot avoid IFI, because. the distances between the HG centers will be of the same order. In general, the golden rule of electroacoustics is one transducer per band, and the brilliant one is one broadband GG for the entire frequency range.

The wavelength of the LF is meters, which is much larger than not only the distance between the GG, but also the size of the speakers. Therefore, manufacturers and experienced amateurs often increase the power of the speakers and improve the bass by pairing or quadrupling (quadruplet) LF GH. However, a beginner should not do this: internal interference of reflected waves “walking” with the speaker itself may occur. To the ear, it manifests itself as resonant NI: it bubbling, gundosing, rattling, why is not clear. So follow the precious rules so as not to sort through the whole speaker over and over again to no avail.

Note: it is impossible to put an odd number of identical GGs in the AS in any case - the FFI is then guaranteed 100%

MF

Novice amateurs pay little attention to the reproduction of medium frequencies - they, they say, any speaker will “sing” - but in vain. MFs are heard best of all, they also account for the original ("correct") harmonics of the basis of everything - basses. The uneven frequency response of the speakers in the midrange is capable of giving combination NI that spoil the sound very much, tk. the spectrum of any phonogram "floats" over the frequency range. Especially - if the speakers use efficient and inexpensive speakers with a short cone stroke, see below. Subjectively, when listening, experts unambiguously prefer speakers with a frequency response to a midrange that smoothly changes over the frequency range within 10 dB over one that has 3 dips or "bumps" of 6 dB each. Therefore, when designing and making speakers, you need to carefully check at every step: will this frequency response not “hunchback” on the midrange?

Note, speaking of bass: rock joke. So, a young promising group broke through to a prestigious festival. In half an hour they will go out, and they are already backstage, worrying, waiting, but the bassist went on a spree somewhere. 10 minutes before the exit - it is not there, 5 minutes - also not. The exit is waving, but the bassist is still missing. What to do? Well, let's play without bass. Absence is an instant collapse of a career forever. They played without bass, it's clear how. They wander to the service exit, spit, swear. Look - a bassist, drunk, with two heifers. They to him - oh you, goat, do you even understand how you threw us?! Where have you been?! - Yes, I decided to listen in the hall. - And what did you hear there? “Dudes, no bass—sucks!”

LF

Bass in music is like the foundation of a house. And in the same way, the "zero cycle" of electroacoustics is the most difficult, complex and responsible. The audibility of sound depends on the energy flux of the sound wave, which depends on the frequency squared. Therefore, the bass is the worst heard, see fig. with curves of equal loudness. To "pump" energy into the bass, you need powerful speakers and UMZCH; in reality, more than half of the power of the amplifier is spent on bass. But at high powers, the probability of the occurrence of NI increases, the strongest and, of course, the audible components of the spectrum of which from the bass will fall just on the best audible mids.

"Pumping" of LFs is further complicated by the fact that the dimensions of the GG and the entire AS are small compared to the wavelengths of LFs. Any source of sound gives it energy the better, the larger its size relative to the wavelength of the sound wave. The acoustic efficiency of the speakers at low frequencies is units and fractions of a percent. Therefore, most of the work and troubles in creating an AU comes down to making it better reproduce low frequencies. But let us remind you once again: do not forget to control the purity of the midrange as often as possible! Actually, the creation of the low-frequency tract of the speaker is reduced to:

• Determination of the required electrical power of LF GG.
• Selecting a LF GH suitable for the given listening conditions.
• The choice of the optimal acoustic design for the selected LF GG (hull design).
• Its correct manufacture in a suitable material.

Power

The sound return in dB (characteristic sensitivity) is indicated in the speaker's passport. It is measured in a sound chamber 1 m from the center of the GG with a measuring microphone located strictly along its axis. The GG is placed on a sound-measuring shield (standard acoustic screen, see the figure on the right) and an electric power of 1 W is supplied (0.1 W for a GG with a power of less than 3 W) at a frequency of 1000 Hz (200 Hz, 5000 Hz). Theoretically, according to these data, the class of the desired Hi-Fi and the parameters of the room / listening area (local acoustics), it is possible to calculate the required electrical power of the GG. But in fact, accounting for local acoustics is so complicated and ambiguous that experts rarely fool around with it.

Note: The GG for measurements is shifted from the center of the screen in order to avoid the interference of sound waves from the front and rear radiating surfaces. The screen material is usually a cake of 5 layers of non-skinned 3-layer pine plywood on casein glue 3 mm thick and 4 gaskets between them made of natural felt 2 mm thick. Everything is glued together with casein or PVA.

It is much easier to go from the existing conditions to the technical sounding of low-noise rooms, corrected for the dynamics and frequency range of Hi-Fi, especially since the results obtained in this case are in better agreement with known empirical data and expert estimates. Then for the initial Hi-Fi it is necessary, with a ceiling height of up to 3.5 m, 0.25 W of the nominal (long-term) electric power of the GG per 1 sq. m floor area, for basic Hi-Fi - 0.4 W/sq. m, and for high - 1.15 W / sq. m.

The next step is to take into account real listening conditions. Hundred-watt speakers capable of operating at microwatt levels are outrageously expensive, on the one hand. On the other hand, if a separate room, equipped as a sound-measuring chamber, is not allocated for listening, then their “microwhispers” on the quietest pianissimo in any living room will not be heard (see above about natural noise levels). Therefore, we increase the obtained values ​​​​by a factor of two or three in order to “tear off” what is being heard from the noise background. We get for the initial Hi-Fi from 0.5 W / sq. m, base from 0.8 W/sq. m and for high from 2.25 W / sq. m.

Further, since we need high-fi, and not just speech intelligibility, we need to move from nominal power to peak (musical) power. The "juice" of the sound depends primarily on the dynamics of its volume. SOI GG at loudness peaks should not exceed its values ​​for Hi-Fi by a class below the chosen one; for the initial Hi-Fi, we take 3% SOI at the peak. In sales specifications for Hi-Fi speakers, peak power is indicated as more significant. According to the Soviet-Russian methodology, the peak power is 3.33 long-term; according to the methods of Western firms, "music" is equal to 5-8 denominations, but - stop for now!

Note: Chinese, Taiwanese, Indian and Korean methods are ignored. They for basic (!) Hi-Fi at the peak take a telephone THD of 6%. But the Philippines, Indonesia and Australia measure their dynamics correctly.

The fact is that without exception, all Western manufacturers of Hi-Fi GG shamelessly overestimate the peak power of their products. It would be better if they promoted their SOI and the evenness of the frequency response, here they really have something to be proud of. Yes, but an ordinary foreign inhabitant will not understand such difficulties, and if “180W”, “250W”, “320W” are smeared on the speaker, this is really cool. In reality, running the speakers "from there" in the sound meter gives them peaks of 3.2-3.7 ratings. Which is quite understandable, because. this ratio is justified physiologically, i.e. structure of our ears. Conclusion - aiming at the Western GG, go to the company website, look for the rated power there and multiply by 3.33.

Note 9, about the designations of the peak and the nominal value: in Russia, according to the old system, the numbers in front of the letters in the designation of the speaker indicated its rated power, and now they give the peak power. But at the same time, the root with the designation suffix was also changed. Therefore, the same speaker can be designated in completely different ways, see examples below. Look for the truth from reference sources or on Yandex. There, no matter what designation you enter, the results will contain a new one, and the old one next to it in brackets.

In the end, we get for a room up to 12 square meters. m peak for the initial Hi-Fi at 15 W, the base at 30 W and the high at 55 W. These are the smallest allowed values; take GG twice or three times more powerful, it will be better, unless you listen to symphonic classics and very serious jazz. For them, it is desirable to limit the power to 1.2-1.5 of the minimum, otherwise wheezing is possible at the peaks of volume.

You can get by even easier by focusing on proven prototypes. For initial Hi-Fi in a room up to 20 sq. m suitable GG 10GD-36K (10GDSH-1 in the old way), for high - 100GDSH-47-16. They do not need filtering, these are broadband GGs. With basic Hi-Fi it is more difficult, a suitable broadband for it is not found, you need to make a 2-way speaker. Here, at first, the optimal solution is to repeat the electrical part of the old Soviet AS S-30B. These speakers have been working properly and very well for decades in apartments, cafes and just on the street. Shabby utterly, but the sound is kept.

S-30B filtering scheme (without overload indication) is shown in fig. left. Minor refinement was made to reduce losses in the coils and the possibility of fitting to various LF GG; if desired, taps from L1 can be made more often, within 1/3 of the total number of turns w, counting from the right end of L1 according to the scheme, the fit will be more accurate. On the right - instructions and formulas for self-calculation and manufacture of filter coils. Precision precision details are not required for this filtering; +/-10% deviations in the inductance of the coils also do not noticeably affect the sound. It is advisable to bring the R2 engine to the back wall for quick adjustment of the frequency response to the room. The circuit is not very sensitive to the impedance of the speakers (in contrast to the filtering on K-filters), therefore, instead of the indicated ones, other HGs can be used that are suitable in terms of power and resistance. One condition: the highest reproducible frequency (HF) of the LF GH at the level of -20 dB must not be lower than 7 kHz, and the lowest reproducible frequency (LF) of the HF GH at the same level must not be higher than 3 kHz. By shifting-pushing L1 and L2, you can somewhat correct the frequency response in the region of the crossover frequency (5 kHz), without resorting to such complexities as the Zobel filter, which can also increase transient distortion. Capacitors - film with PET or fluoroplastic insulation and sprayed plates (MKP) K78 or K73-16; in extreme cases - K73-11. Resistors - metal film (MOX). Wires - audio from oxygen-free copper with a cross section of 2.5 square meters. mm. Mounting - soldering only. On fig. the right side shows what the original S-30B filtering looks like (with the overload indication circuit), and in fig. below on the left is a 2-way filtering scheme popular abroad without magnetic coupling between the coils (why their polarity is not indicated). On the right there, just in case, is a 3-way filtering of the Soviet AC S-90 (35AC-212).

About wires

Special audio wires are not a product of mass psychosis and not a marketing gimmick. The effect discovered by radio amateurs is now confirmed by research and recognized by experts: if there is an admixture of oxygen in the copper of the wire, the thinnest, literally in a molecule, oxide film is formed on the metal crystallites, from which the sound signal can be anything but an improvement. In silver, this effect is not found, which is why sophisticated audio gourmets do not skimp on silver wire: merchants shamelessly cheat with copper wires, because. it is possible to distinguish oxygen-free copper from ordinary electrical engineering only in a specially equipped laboratory.

Speakers

The quality of the primary sound emitter (FROM) on the bass determines the sound of the speakers approx. by 2/3; in the midrange and highs - almost completely. In amateur speakers, almost always IZs are electrodynamic GGs (speakers). Isodynamic systems are quite widely used in high-end headphones (for example, TDS-7 and TDS-15, which are readily used by pros to control sound recording), but the creation of powerful isodynamic IS faces technical difficulties that are still insurmountable. As for the other primary ISs (see the list at the beginning), they are still far from “brought to mind”. This is especially true for prices, reliability, durability and stability of characteristics during operation.

When joining electroacoustics, you need to know the following about how speakers are arranged and work in acoustic systems. The exciter of the speaker is a thin coil of wire oscillating in the annular gap of the magnetic system under the influence of an audio frequency current. The coil is rigidly connected to the sound emitter itself into space - a diffuser (for bass, midrange, sometimes for high frequencies) or a thin, very light and rigid dome diaphragm (for high frequencies, rarely - for midrange). The efficiency of sound emission strongly depends on the diameter of the IZ; more precisely, it depends on its relation to the wavelength of the emitted frequency, but at the same time, with an increase in the diameter of the IZ, the probability of occurrence of non-linear distortions (NI) of the sound due to the elasticity of the IZ material also increases; more precisely - not its infinite rigidity. They fight against NI in IZ by making radiating surfaces from sound-absorbing (anti-acoustic) materials.

The diameter of the cone is larger than the diameter of the coil, and in diffuser GGs, it and the coil are attached to the speaker housing with separate flexible suspensions. The diffuser configuration is a thin-walled hollow cone with its apex facing the coil. The suspension of the coil simultaneously holds the top of the diffuser, i.e. its suspension is double. The generatrix of a cone can be rectilinear, parabolic, exponential and hyperbolic. The steeper the cone of the diffuser converges to the top, the higher the return and the lower the NI dynamics, but at the same time its frequency range narrows and the radiation directivity increases (the radiation pattern narrows). The narrowing of the DN also narrows the area of ​​the stereo effect 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 drastically reduces the SOI GG, because. the diffuser suspension is a very noticeable source of NI sound, and the material for the diaphragm can be taken very hard. However, the diaphragm is capable of emitting sound well only at sufficiently high frequencies.

The coil and the diffuser or diaphragm, together with the suspensions, make up the mobile system (PS) of the GG. The PS has a frequency of its own mechanical resonance Fp, at which the mobility of the PS increases sharply, and a quality factor Q. If Q> 1, then the speaker without a properly selected and executed acoustic design (see below) at Fp will wheeze at a power less than the nominal one, not that peak, this is the so-called. blocking GG. Locking does not apply to distortions, because is a design and manufacturing defect. If 0.7

The efficiency of transferring the energy of an electrical signal from the 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), since air is highly compressible and highly fluid. The instantaneous acceleration of the coil pushing/pulling the diffuser/diaphragm must be somewhat greater, otherwise it will not "shake" the OUT. A few, but not 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 stronger the emitter “slows down”, the stronger it radiates. In practice, the "braking" of the emitter is done in such a way that its NI in the entire frequency and power range fit into the norm for a given Hi-Fi class.

Note, output: do not try to "squeeze" out of the speakers what they cannot. For example, speakers on 10GDSh-1 can be built with a frequency response unevenness at the midrange of 2 dB, but in terms of SOI and dynamics, it still pulls on Hi-Fi no higher than the initial one.

At frequencies up to Fp, the membrane effect never manifests itself, this is the so-called. piston mode of operation of the GG - the diffuser / diaphragm just go back and forth. Higher in frequency, the heavy diffuser is no longer able to keep up with the coil, the membrane radiation starts and gets stronger. At a certain frequency, the speaker begins to radiate only as a flexible membrane: at the junction with the suspension, its diffuser is already motionless. At 0.7

The membrane effect dramatically improves the return of GG, tk. the instantaneous accelerations of the vibrating sections of the IZ surface turn out to be very large. This circumstance is widely used by designers of HF and partially MF GG, the distortion spectrum of which immediately goes into ultrasound, as well as when designing GG 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. In the zero mode, when the entire surface of the FM trembles as if in time with itself, Hi-Fi up to the middle inclusive can be achieved at low frequencies, see below.

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

Woofers

High-quality piston woofers GG (simply - “piston”; in English woofers, barking) are made with a relatively small, thick, heavy and hard anti-acoustic cone on a very soft latex suspension, see pos. 1 in fig. Then Fr is below 40 Hz or even below 30-20 Hz, and Q<0,7. В мембранном режиме поршневые ГГ способны работать до частот 7-8 кГц на нулевой-первой модах.

The periods of low-frequency waves are long, all this time the diffuser in the piston mode must move with acceleration, and therefore the diffuser stroke becomes 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. of the attached air, for the “buildup” of which a significant effort is required (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 return of the piston GG is small, because. it is impossible for a low-frequency diffuser to develop a large acceleration at long waves: the elasticity of the air is not enough to accept the energy given off. It will spread to the sides, and the speaker will go into locking. In order to increase the return and smoothness of the motion of the moving system (to reduce SOI at high power levels), designers go all out - they use differential magnetic systems, with half-scattering, and other exotics. THD is further reduced by filling the magnetic gap with a non-drying rheological fluid. As a result, the best modern pistons reach 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 for a pair with differential magnets and refilling for home acoustics, matched in terms of output, 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 incapable of working in the membrane mode.

Piston GGs have another serious flaw: without strong acoustic damping, they can mechanically collapse. Again, simply: behind the piston speaker there should be a kind of air cushion loosely connected to the free space. Otherwise, the diffuser at the peak will break off the suspension and it will fly out along with the coil. Therefore, you can not put the "piston" in any 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, the speaker cones are usually not held by hand and matches are not inserted into the magnetic gap.

Craftsmen take note

There is a known “folk” way to increase the return of piston GGs: from the rear, without altering anything in dynamics, an additional annular magnet is firmly attached to the standard magnetic system with the repelling side. It is repulsive, otherwise, when a signal is applied, 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 nowhere else has a rewinding speaker become better or at least remain the same as it was.

But it's not really about that. Enthusiasts of this refinement claim that the field of the external magnet concentrates the field of the standard one near the coil, which increases the acceleration of the PS and the return. This is true, but Hi-Fi GG is a very finely balanced system. Recoil is actually a little higher. But here the SOI at its peak immediately "jumps" so that sound distortions become well audible even to inexperienced listeners. At nominal, the sound can become even cleaner, but without Hi-Fi speakers it’s already high-fi.

Leading

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

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

Note: silk is added to the cone material of almost all good speakers, it is a universal way to reduce THD.

Tweeters

In our opinion - squeakers. As you may have guessed, these are tweeters, HF YY. Spelled with a single t, it's not a gossip social media name. It would be generally easy to make a good “tweeter” from modern materials (the NI 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 or less than the wavelength. Because of this, interference is possible on 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 selection criterion for the HF GG is indicated above: dome ones are universal, and for fans of the classics who require necessarily “singing” soft tops, diffuser ones are more suitable. It is better to take these elliptical ones and put them in the speakers, orienting their long axis vertically. Then the dynamics of the speaker in the horizontal plane will be wider, and the stereo zone will be larger. Still on sale there is a HF GG with a built-in horn. Their power can be taken as 0.15-0.2 of the power of the low-frequency link. As for technical quality indicators, any HF GG is suitable for Hi-Fi of any level, as long as it is suitable in terms of power.

Widths

This is a colloquial nickname for broadband GGs (GGSh) that do not require defiltering of AC frequency channels. The emitter of a simple GGSh with a common excitation consists of an LF-MF diffuser and a HF cone rigidly connected to it, pos. 3. This is the so-called. a coaxial radiator, which is why the GGSh is also called coaxial speakers or simply coaxes.

The idea of ​​​​GGSh is to give the membrane mode to the HF cone, where it does not particularly harm, and let the diffuser on the bass and at the bottom of the midrange work “on the piston”, for which the bass-midrange cone is corrugated across. This is how broadband GGs are made for initial, sometimes average Hi-Fi, for example. mentioned 10GD-36K (10GDSH-1).

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

Coaxial GGSh with separate excitation of LF-MF and HF emitters, pos. 4, this shortcoming is devoid of. In them, the RF link is driven by a separate coil from its own magnetic system. The sleeve of the HF coil passes through the LF-MF coil. PS and magnetic systems are located coaxially, i.e. along one axis.

GGSh with separate excitation at low frequencies in all technical parameters and subjective sound assessments are not inferior to piston GGs. On modern coaxial speakers, you can build very compact speakers. The disadvantage is the price. A coaxial for high Hi-Fi is usually more expensive than a LF-MF + HF set, although it is cheaper than LF, MF and HF for a 3-way speaker.

Auto

Car speakers formally also belong to coaxial speakers, but in reality they are 2-3 separate speakers in one case. HF (sometimes midrange) GG are suspended in front of the diffuser LF GG on the bracket, see on the right in fig. at the beginning. Filtering is always built-in, i.e. There are only 2 terminals on the case for connecting wires.

The task of auto speakers is specific: first of all, to “shout out” the noise in the car, so their designers don’t really struggle with the membrane effect. But for the same reason, auto-speakers need a wide dynamic range, at least 70 dB, and their diffusers are necessarily made with silk or use other measures to suppress higher membrane modes - the speaker should not wheeze even in a car on the move.

As a result, auto speakers are in principle suitable for Hi-Fi up to medium inclusive, if you choose the right acoustic design for them. In all the speakers described below, you can put auto-speakers of a suitable size and power, then you will not need 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 wiring. Speakers made from modern car speakers allow you to listen to good jazz, rock, even individual pieces of symphonic music and many chamber music. Of course, they won't pull Mozart's violin quartets, but very few people listen to such dynamic and meaningful opuses. A pair of auto speakers will cost several times, up to 5 times, cheaper than 2 sets of GG with filter components for a 2-way speaker.

frisky

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

Manufacturers and sellers do not single out “frisky” in a special class, because. they are, in theory, not Hi-Fi. The speaker is like a speaker in any Chinese radio or cheap computer speakers like that. However, on the "frisky" one can make good speakers for the computer, providing Hi-Fi up to and including the average in the vicinity of the desktop.

The fact is that the "frisky" ones are able to reproduce the entire sound range, you only 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 navigate by the manufacturer and his (not trade!) Specifications. For example, all GGs of the Canadian company Edifier with silk. By the way, Edifier is a French word and is read "edifier" and not "idifier" in the English manner.

The frequency response of the "frisky" is leveled in two ways. Small bursts / dips are already removed by silk, and larger bumps and troughs are eliminated by acoustic design with free exit to the atmosphere and a damping prechamber, see Fig. see an example of such an AS 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 just put 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 you won’t hear bass at all. This is called an acoustic short circuit. You can’t just muffle the speaker from the rear to the bass: the cone will have to strongly compress a small volume of air, which is why the resonance frequency of the PS will “jump” so high that the speaker simply cannot reproduce the bass. From here follows the main task of any acoustic design: either to extinguish the radiation from the rear side of the GG, or to turn it over by 180 degrees and re-emit it in phase from the front of the speaker, while at the same time preventing the expenditure of the energy of the diffuser movement on thermodynamics, i.e. on compression-expansion of air in the AC case. An additional task is, if possible, to form a spherical sound wave at the output of the speaker, because in this case, the stereo effect zone is the widest and deepest, and the effect of room acoustics on the sound of the speakers is the least.

Note, an important corollary: for each speaker cabinet of a specific volume with a specific acoustic design, there is an optimal excitation power range. If the output power is low, it will not swing the acoustics, the sound will be dull, distorted, especially at low frequencies. An excessively powerful GG will go into thermodynamics, which will cause blocking.

The purpose of the speaker cabinet with acoustic design is to provide the best reproduction of low frequencies. Durability, 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 an acoustic impedance panel (PAS), a closed box of normal or reduced volume (small-sized acoustic systems, MAC), a phase inverter (FI), passive radiator (PI), direct and reverse horns, quarter-wave (HF) and half-wave (HF) labyrinths.

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

• Unlike others, except FI and PI, PV labyrinth allows you to improve bass at frequencies below the natural resonant frequency of the woofer.
• Compared to the FI PV, the labyrinth is structurally and easy to set up.
• Compared to PI PV, the labyrinth does not require expensive purchased additional components.
• The cranked 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 low-frequency GG with both long and short diffuser strokes. Up to replacement in already built speakers. Of course, only a couple. The radiated wave in this case will be almost spherical.
• Unlike all, except for the closed box and the HF labyrinth, the acoustic column with the PV labyrinth is able to smooth out the frequency response of the LF GG.
• Speakers with a PV labyrinth are structurally easily pulled into a tall thin column, which facilitates their placement in small rooms.

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

PV maze

Labyrinths are often considered acoustic design such as a deep slot (Deep Slot, a type of HF labyrinth), pos. 1 in Fig., and convolutional reverse horn (pos. 2). We will touch on the horns, but as for the deep slot, this is actually a PAS, an acoustic shutter that provides free communication with the atmosphere, but does not let sound out: the depth of the slot is a quarter of the wavelength of its tuning frequency. It is easy to verify this by measuring the sound levels in front of the front of the speaker and in the opening of the slot using a highly directional microphone. Resonance at multiple frequencies is suppressed by lining the gap with a sound absorber. A deep slot speaker also dampens any speakers, but raises their resonant frequency, albeit less than a closed box.

The initial element of the PV labyrinth is an open half-wave pipe, pos. 3. As an acoustic design, it is unsuitable: while the wave from the rear reaches the front, its phase will be reversed by another 180 degrees, and the same acoustic short circuit will turn out. On the frequency response of the PV, the pipe gives a high sharp peak, causing the GG to lock at the tuning frequency Fn. But what is already important - Fn and the natural resonance frequency of the GG f (which is higher - Fp) are theoretically not related to each other, i.e. bass can be expected to improve below f (Fp).

The easiest way to turn a pipe into a maze 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 paths of the waves in the pipe will now be different in length. In this way, in principle, it is possible to smooth the frequency response to any predetermined degree of evenness by increasing the number of knees (it should be odd), but in reality it is very rare to use more than 3 knees - the damping of the wave in the pipe interferes.

In the chamber PV labyrinth (pos. 5), the knees are divided into the so-called. Helmholtz resonators - cavity tapering towards the rear end. This further improves the damping of the HG, 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 "backwater" from the last chamber. Having partitioned the chambers on intermediate resonators, pos. 6, it is possible to achieve a frequency response with a diffuser GG that almost satisfies the requirements of absolute Hi-Fi, but setting up each of a pair of such speakers requires somewhere from six months (!) of the work of an experienced specialist. Once upon a time, in a certain narrow circle, the labyrinth-chamber speaker with chamber separation was called Cremona, with a hint of the unique violins of Italian masters.

In fact, to obtain a frequency response for high Hi-Fi, it turns out that just a pair of cameras on the knee is enough. Drawings of speakers of this design are given in Fig; on the left - Russian development, on the right - Spanish. Both are very good outdoor acoustics. “For complete happiness”, it would not hurt the Russian woman to borrow the Spanish stiffness ties that support the partition (beech sticks with a diameter of 10 mm), and in return to give a smoothing of the pipe bend.

In both of these speakers, one more 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. In reality, the lower limit of the frequency range is 37-45 Hz, depending on the type of LF GG. When the S-30B's filtered speakers are rearranged 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 - synthetic winterizer 5-10 mm. Tuning is not always necessary and easy: if the bass is deaf, the port is covered symmetrically on both sides with pieces of foam until the optimal sound is obtained. This should be done slowly, each time listening to the same segment of the phonogram for 10-15 minutes. It must have strong mids with a sharp attack (mids control!), For example, a violin.

jet flow

The chamber labyrinth is successfully combined with the usual tortuous one. An example is the desktop acoustic system Jet Flow (jet stream) developed by American radio amateurs, which made a splash in the 70s, see fig. on right. Case width on the inside - 150-250 mm for speakers 120-220 mm, incl. "frisky" and autodynamics. Body material - pine, spruce, MDF. Sound-absorbing lining and adjustment are not required. Excitation power range - 5-30 W peak.

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

For high-spirited and computer

It is also possible to smooth out the frequency response of auto-speakers and “frisky” ones in an ordinary convoluted labyrinth by arranging a compression damping (not resonating!) prechamber in front of its entrance, indicated by K in fig. below.

This mini speaker is designed for PC instead of the old cheap one. The speakers used are the same, but how they start to sound is simply amazing. If the diffuser is with silk, otherwise it makes no sense to fence the garden. An additional advantage is a cylindrical body, on which the midrange interference is close to the minimum, it is less only on a spherical body. Working position - with an inclination forward-up (AC - sound projector). Excitation power - 0.6-3 W nominal. Assembly is carried out in the following. order (glue - PVA):

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

About horns

Horn speakers have a high return (remember why he just does it, a mouthpiece). The old 10GDSH-1 yells through a horn so that the ears wither, and the neighbors “I can’t be happy at all”, which is why many are addicted to horns. In home speakers, convoluted horns are used as less bulky. The reverse horn is excited by the rear 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 much more complicated, see fig. below.
2. It does not improve, but on the contrary, 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 to correct its frequency response in principle.
3. The radiation from the horn port is significantly directed, and its wave is rather flat than spherical, so a good stereo effect cannot be expected.
4. It does not create a significant acoustic load of the GG and at the same time requires significant power for excitation (we also remember whether they whisper into a speakerphone). The dynamic range of horn speakers can be extended at best to basic Hi-Fi, and for piston speakers with a very soft suspension (and therefore good and expensive ones), the cone breaks out very often when the GG is installed in the horn.
5. Gives overtones more than any other type of acoustic design.

Frame

The speaker cabinet is best assembled on beech dowels and PVA glue, its film retains its damping properties for many years. For assembly, one of the sidewalls is placed on the floor, the bottom, lid, front and rear walls, partitions are placed, see fig. on the right, and cover with the other sidewall. If the outer surfaces are to be finished, steel fasteners can be used, but always with gluing and sealing (plasticine, silicone) of non-glue seams.

Much more important for sound quality is the choice of body material. The ideal option is a musical spruce without knots (they are a source of overtones), but it is unrealistic to find its large boards for speakers, because Christmas trees are very knotty trees. As for the plastic cases of the speakers, they sound good only in industrial production, solid-cast, and amateur home-made products 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, it is difficult with natural wood materials for speakers: completely straight-grained pine without defects is expensive, and other available building and furniture species give overtones. It is best to use MDF. The Edifier mentioned above has long since completely switched to it. The suitability of any other tree for AS can be determined as follows. way:

1. The test is carried out in a quiet room, in which you yourself must first stay in silence for half an hour;
2. Piece of board approx. 0.5 m is placed on prisms from segments of a steel corner, laid at a distance of 40-45 cm from each other;
3. The knuckle of a bent finger knocks 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 better, the softer, duller and shorter the sound. According to the results of such a test, you can make good speakers even from chipboard or laminate, see the video below.