Do-it-yourself two-way speaker on alfard speakers. Homemade speaker system. What to make of? Plywood, MDF, chipboard, plastic, solid wood

Acoustic speakers

The sound quality in the car depends on the location of the speakers. In addition, the resonance of the enclosures is also important in this matter.
Therefore, the case of the speaker used in this case must be made of a material that has sufficient resonance. As a result of this, the most suitable option would be to create columns with your own hands.
How to do it yourself acoustic speakers, you can find out from our article. The information will help you learn not only how to make speakers yourself, but also how to assemble a real speaker system.

Creating conditions for a column

First of all, you need to find out what size the column will be. To do this, you should decide on its location.
Most often, the speaker is installed in the trunk, since there is enough space for it to have enough space. In addition, a kind of resonance is also created in the luggage compartment, so the music sounds a little different here.
The speakers can be installed near the rear window, but here they will have to be more compact, since massive speakers may not fit here.

Note. However, this again depends on the position of the column: standing or lying down.

Measuring dimensions

To find out the size of the box for the column, you should:

Decide on its location.
Determine how much space you can set aside.
Measure the size of the allotted area.

Note: For a speaker in the luggage compartment, a 30 cm length is enough. But the speakers installed behind the rear seat should not have more than 15 cm.

Material selection

To create a column, the following materials are quite suitable:

Chipboard. By the way, finding this material can be much easier than the others, since it is often found on sale. Moreover, its price is quite affordable.
Advantage of this material is that it has a fairly large impact, so the sound of the speakers will not be distorted. Also, this material is the lightest, so the structure will not be too heavy.
Hard rubber (ebonite). The products are pretty good, but the sound will be a little muffled. And it is not so easy to find rectangular pieces of ebonite on sale.
In addition, the product may have an unpleasant odor. The most important advantage: ebonite is difficult to ignite, so if a short circuit occurs, the column case will not burn out.

Wood. Any wood will do.
In this case, it is better to give preference to oak or pine, since with their help you can create a good resonance. Also, the advantage of the material is its attractive appearance.

Note: such a product can even be dyed, so it will turn out to be very beautiful.

Corpus creation

You can make the body in any convenient way.
The most suitable option is the following:

Use a hacksaw to cut parts out of the material.
Select the parts to which the speakers will be attached. Round holes should be made in their central part.

Note: The hole diameter must match the diameter of the bottom of the speaker.

It is also necessary to cut out small rings that will be attached to the bottom of the holes made (so that the speaker is securely fixed). The shape of these rings should resemble a plate without a bottom.
Glue rings to parts.
Around the rings in the details, make more holes in the shape of a triangle with rounded corners.

Note: this is necessary in order for the sound to penetrate into the case, and not only come out.

For the inner part of the case, small partitions should also be made (their length should correspond to the length of the case itself). With their help, the bass reflex will be held.
Make small ports through which the terminals will be fixed.

Column assembly

To collect all the parts into one whole, you should:

Connect the body parts using glue or self-tapping screws: rectangular parts on the sides, the bottom part, and the part with a hole on the top.
Fill the inside of the column with synthetic down.
Place the speaker in the intended place.

Note: The speaker wiring can be removed through any hole that you can conveniently create.

Paint the frame with varnish. Thus, he will have a finished appearance.

Note: It is not necessary to use varnish for painting. Black paint can come in handy for this. And some details can be done in a different color altogether.

Building a speaker system

The speaker system does not always indicate the presence of speakers.
You can work on creating a speaker system in a car like this:

Make foam podiums. For this:
Make a template out of cardboard. Attach it to the place where the podium should be.
Using the template, cut out the base for the podium. For this purpose, ordinary plywood and fittings can be useful.
The base consists of two rings. In this case, the diameter of the first ring must correspond to the diameter of the protective mesh. But the diameter of the second is the diameter of the column.
The rings must be connected to each other using self-tapping screws.
Cut six sticks to create a slope. Glue all the details together.
Pour polyurethane foam into the frame and leave it there until it dries.
You get a more interesting option if you use small pieces of different types of trees instead of plywood. In this case, you should pick up dry pieces of wood that do not have cracks. From above, everything should be carefully varnished to make the design more reliable. For greater efficiency, everything can be secured with two rails.
Mount speakers in jacks and install podiums.

Thus, you can create acoustic speakers (see) right at home and with your own hands. The price of such a pleasure will not be high, since it will only be necessary to spend money on the purchase of material.
Anyway, you can use any old speakers. The main thing is that they work and be in good condition.
Of course, before starting this process, it is worth reviewing various photos and videos with this topic. The instruction will also come in handy.

To make speakers with your own hands - this is how many people begin their passion for a complex, but very interesting business - the technique of sound reproduction. The initial impulse is often economic considerations: prices for branded electroacoustics are not overstated, not excessively - ugly brazenly. If the sworn audiophiles, who do not skimp on rare radio tubes for amplifiers and flat silver wire for winding sound transformers, complain on the forums that the prices for acoustics and speakers are systematically inflating for it, then the problem is really serious. Do you want speakers for the home for 1 million rubles. pair? Excuse me, there are more expensive ones. That's why the materials of this article are designed primarily for the very beginners: they need to quickly, simply and inexpensively make sure that the creation of their own hands, for which everything was spent tens of times less than the “cool” brand, can “sing” as well, or at least be comparable. But probably, some of the above will be a revelation for the masters of amateur electroacoustics- if honored with reading these.

Column or speaker?

Sound column (KZ, sound column) is one of the types of acoustic design of electrodynamic loudspeaker heads (GG, speakers), intended for technical and informational sounding of large public spaces. In general acoustic system(AC) consists of a primary sound emitter (IZ) and its acoustic design, providing 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, crossover filters, built-in audio frequency power amplifiers (UMZCH, in active speakers), computing devices (in speakers with digital channel filtering), etc. is usually placed in the body, which is why they look more or less elongated upward columns.

Acoustics and electronics

The acoustics of an ideal speaker system is excited in the entire range of audible frequencies of 20-20,000 Hz by one broadband primary IZ. Electroacoustics is slowly but surely moving towards the ideal, however, 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, medium) and HF (5000 -20,000 Hz, high, high) 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) at home without unnecessary costs and difficulties. Sound signal from UMZCH or, in active speakers, low-power from a primary source (player, sound card computer, tuner, etc.) is distributed among the frequency channels by crossover filters; this is called channel de-filtering, just like the crossover filters themselves.

The rest 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. It should only be noted here that, firstly, at first, you do not need to tackle a close to ideal, but complex and expensive digital filtering, but apply a passive one on inductive-capacitive filters. A 2-way speaker requires only one LPF / HPF crossover plug.

For the calculation of AC ladder separation filters there is special programs e.g. JBL Speaker Shop. However, at home, the individual tuning of each plug for a specific specimen of speakers, firstly, does not hit on production costs in mass production. Secondly, the replacement of the GG in the AU is required only in exceptional cases. This means that you can approach the filtering of the frequency channels of the speaker in an unconventional way:

The frequency of the LF-MF and HF section is taken at least 6 kHz, otherwise a sufficiently uniform amplitude-frequency characteristic (AFC) of the entire speaker in the MF region will not turn out, which is very bad, see below. In addition, at a high crossover frequency, the filter is inexpensive and compact;
The prototypes for calculating the filter are the links and half-links of the K-type filters, since their phase-frequency characteristics (PFC) are absolutely linear. Without this condition, the frequency response in the section frequency area will turn out to be significantly uneven and overtones will appear in the sound;
To obtain the initial data for the calculation, it is necessary to measure the impedance (total electrical resistance) of the LF-MF and HF GG at the crossover frequency. The 4 or 8 ohms indicated in the GG passport are their active resistance at direct current, 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 (GZCH), tuned to the crossover frequency, with an output of at least 10 V to a load of 600 Ohm through a resistor of obviously high resistance, for example. 1 kΩ. You can use a low-power GZCH and UMZCH of high fidelity. The impedance is determined by the ratio of the audio frequency (AF) voltages across the resistor and GG;
The impedance of the LF-MF link (GG, head) is taken as the characteristic impedance ρн of the filter low frequencies(Low-pass filter), and the impedance of the high-frequency head - for ρ in the high-pass filter (high-pass filter). The fact that they are different - well, a joke with them, the output resistance of the UMZCH, "swinging" the speaker, is negligible in comparison with that and that;
From the side of the UMZCH, LPF and HPF of the reflecting type are installed so as not to overload the amplifier and not take power from the paired AC channel. On the contrary, the absorbing links are drawn to the GG, so that the recoil from the filter did not give overtones. Thus, the low-pass filter and the high-pass filter of the AC will have at least a link with a half-link;
The attenuation of the LPF and HPF at the crossover frequency is taken equal to 3 dB (1.41 times), since the slope of the slopes of the K-filters is small and uniform. Not 6 dB, as it might seem, because filters are calculated by voltage, and the power supplied to the GG depends on it in a square;
Adjusting the filter is reduced to "muffling" a channel that is too loud. The channel loudness is measured at the crossover frequency using a computer microphone, turning off the HF and LF-MF in turn. The degree of "jamming" is defined as the square root of the ratio of the loudness of the channels;
The excess volume of the channel is removed by a pair of resistors: the one that quenches by fractions or units of Ohm is connected in series with the GG, and in parallel to both of them - equalizing the greater resistance so that the impedance of the GG with resistors remains unchanged.

Explanation of the method

A technically savvy reader may have a question: do you have a complex load filter working? Yes, and in this case, it's okay. The phase response of the K-filters is linear, as mentioned, and the Hi-Fi UMZCH is an almost ideal voltage source: its output resistance Rout is units and tens of mΩ. Under such conditions, the "reflection" from the reactance of the GG will partially damp in the output absorbing link / half-link of the filter, but for the most part it will seep back to the output of the UMZCH, where it will disappear without a trace. In fact, nothing will pass into the conjugate channel, because ρ of its filter is many times greater than Rout. There is one danger: if the impedance of the GG and ρ are different, then the power circulation will begin in the filter output - GG circuit, which will cause the bass to become dull, "flat", the attacks on the midrange will be prolonged, and the top will be sharp, with a whistle. Therefore, it is necessary to adjust the impedance of the GG and ρ exactly, and in the case of replacing the GG, the channel will have to be re-tuned.

Note: do not try to filter active speakers with analog active filters on operational amplifiers (op amps). It is impossible to achieve 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 high-fi

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 gradually developed an informal division of it into classes; the numbers in the list indicate, respectively, the reproducible frequency range (operating range), the maximum permissible harmonic distortion (THD) at rated power (see below), the minimum permissible dynamic range relative to the internal noise of the room (dynamics, the ratio of maximum volume to minimum), the maximum permissible unevenness of the frequency response at the midrange and its blockage (decline) at the edges of the working 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 - 31.5-18000 Hz, 0.1% (–60 dB), 75 dB (5600 times), 2 dB, 3 dB (1.41 times).
Medium or basic - 40-16000 Hz, 0.3% (–50 dB), 66 dB (2000 times), 3 dB, 6 dB (2 times).
Initial - 63-12 500 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. The Anglo-Saxons called the Heavy high Hi-Fi, because High High Fidelity in English is like butter.

What kind of high-fi do you need?

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

Firstly, literally a few people from all of humanity hear the full range of audio frequencies. People gifted with a particularly fine ear for music, such as Mozart, Tchaikovsky, J. Gershwin, hear high Hi-Fi. Experienced professional musicians in a concert hall, basic Hi-Fi is confidently perceived, 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 distinguishes sounds in the range of 140 dB by dynamics, counting from the hearing threshold of 0 dB, which is equal to the intensity of the sound flow of 1 pW per sq. m, see fig. on the right are curves of equal loudness. A sound louder than 140 dB is already pain, and then hearing damage and contusion. An expanded symphony orchestra on a powerful fortissimo produces sound dynamics of up to 90 dB, and in the halls of the Bolshoi Opera, Milan, Paris, Vienna opera houses and the Metropolitan Opera in New York, it can “accelerate” up to 110 dB; so is the dynamic range of the leading jazz bands with symphonic accompaniment. This is the limit of perception, louder than which the sound turns into a still bearable, but already meaningless noise.

Note: rock bands can play even louder than 140 dB than 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 tender pianissimo with all their desire - the equipment does not allow it, and there is no such thing as rock. As for pop music of any kind and movie soundtracks, this is not a topic at all - their dynamic range is already compressed during recording to 66, 60 and even 44 dB, so that you can listen to anything.

Thirdly, natural noises in the quietest living room of a country house behind the backyards of civilization are 20-26 dB. The sanitary standard for noise in the reading room of the library is 32 dB, and the rustle of leaves in the fresh wind is 40-45 dB. Hence, it is clear that 75dB high hi-fi speakers are more than enough for meaningful listening in a domestic environment; the dynamics of modern UMZCH 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 with more than 26 dB of noise, the frequency range of the selected Hi-Fi can be narrowed down to pre. class, because the masking effect affects - against the background of indistinct noise, the frequency sensitivity of the ear 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 less distortion of sound, correct reproduction of low frequencies, smooth frequency response in the midrange area, and determine the required sound for this room electrical power AC. As a rule, there are no problems with HF, tk. their SOI "go" into the inaudible ultrasound area; you just need to put a good tweeter in the speaker. It is enough to note here that if you prefer classical and jazz, it is better to take the HF GG with a diffuser for a power of 0.2-0.3 from that of the LF 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 LF link will be optimal; only domed "tweeters" naturally reproduce the drumming with brushes. However, a good HF dome HG is suitable for any kind of music.

Distortion

Distortions of sound are possible linear (LI) and non-linear (LI). Linear distortion is simply a mismatch of the average volume level for listening conditions, for which there is a volume control in any UMZCH. In expensive 3-way speakers for high Hi-Fi (for example, the Soviet AC-30, they are also S-90), power attenuators for the midrange and high frequency are often introduced in order to match the frequency response of the speakers to the acoustics of the room as accurately as possible.

As for NI, they, as they say, are innumerable and new ones are constantly being discovered. The presence of NI in the sound path is expressed in the fact that the shape of the output signal (which is already in the air) is not completely identical to the shape of the original signal from the primary source. Most of all spoil the purity, "transparency" and "juiciness" of the sound of the trace. NOR:

Harmonic - overtones (harmonics), multiples of the fundamental frequency of the reproduced sound. They appear as excessively booming bass, sharp and hard midrange and treble;
Intermodulation (combinational) - the sum and difference 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 be recognized only in the laboratory using multi-signal or statistical methods on test phonograms. By ear, the sound seems to be clear, but somehow not so;
Transient - "jitter" of the output signal with sharp rises / falls of the original. They manifest themselves with short wheezing and sobbing, but irregularly, at volume jumps;
Resonant (overtones) - ringing, bouncing, bubbling;
Frontal (distortion of sound attack) - delaying or, conversely, forcing sharp changes in the overall volume. Almost always occur in conjunction with transitional;
Noisy - hum, rustle, hiss;
Irregular (sporadic) - clicks, cod;
Interference (AI or IFI, so as not to be confused with intermodulation). They are characteristic precisely for the AU, they do not appear in the UMZCH. They are very harmful because perfectly audible and irreparable without major alteration of the speaker. For more information on the IFI, see below.

Note:"Wheezing" and other figurative descriptions of distortion are hereinafter 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 rated power of 6% (in China - by 10%) and 1

In addition to interference, AS can give predominantly NI according to PP. 1, 3, 4 and 5; clicks and pops are possible here as a result of poor-quality workmanship. They struggle with transitional and frontal NIs in the AU, selecting suitable GGs (see below) and acoustic design for them. Ways to avoid overtones - a rational design of the speaker cabinet and the correct choice of material for it, also see below.

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

The only way to cope with all this disgrace is to hide the NI deeper under the amplifier's own noises, 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 present ideas, UMZCH with 1% THD and -66 dB noise is "no", and with 0.06% THD and -80 dB noise is pretty average.

This is not the case with harmonic NI speaker speakers. 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, also like lamps, no higher than the 4th. Such a spectrum of NI does not noticeably spoil the sound even with a THD 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 at the midrange. For your information, if the trumpeter has not properly cleaned the instrument before the concert and does not spill saliva out of the ear cushion in time while playing, then the THD of, say, a trombone can grow to 2-3%. And nothing, they play, the listeners like it.

The conclusion from this is very important and favorable: the range of reproducible frequencies and natural harmonic NI speakers are not parameters that are critically important for the quality of the sound it creates. Experts can attribute the sound of speakers with 1% and even 1.5% harmonic NI to basic, and even high Hi-Fi, if they are fulfilled accordingly. conditions for the dynamics and smoothness of the frequency response.

Interference

IFI is the result of convergence of sound waves from nearby sources in phase or in antiphase. The result is bursts, up to rubbing in the ears, or dips of almost zero, loudness 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 at all for the second octave (as far as I remember). At the plant, the prototype was "driven" in a sound scale using a three-signal method, antediluvian even then, and the position of an expert with an ear for music was not on the staff list. One of the paradoxes of developed socialism.

The likelihood of the occurrence of IFI increases sharply with increasing frequency and, accordingly, decreasing the wavelength of sound, because for this, the distance between the centers of the emitters must be a multiple of half the wavelength of the reproduced frequency. On the MF and HF, the latter varies from units of decimeters to millimeters, therefore, it is impossible to put two or several MF and HF GG in the speaker in any way - then IFI cannot be avoided, because the distances between the centers of the HH will be of the same order. In general, the golden rule of electroacoustics is one emitter per band, and the brilliant rule is one broadband GG for the entire frequency range.

The LF wavelength is meters, which is much larger than not only the distance between the GG, but also the size of the speaker. Therefore, manufacturers and experienced amateurs often increase the power of the speakers and improve the bass by pairing or quadruplet (quadruplet) the low frequency of the GG. However, a beginner should not do this: internal interference of reflected waves, "walking" from the speaker itself, may occur. To the ear, it manifests itself as a resonant NI: cocks, gundosit, rattles, why is not clear. So follow these precious rules so that you don't go over and over all the speakers to no avail.

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

Midrange

Beginning amateurs pay little attention to the reproduction of middle frequencies - they, they say, any speaker will "sing" - but in vain. The midrange is heard best of all, they also account for the original ("correct") harmonics of the basis of everything - the bass. The unevenness of the frequency response of the speakers at the midrange is capable of giving very strong combinational NIs that spoil the sound, tk. the spectrum of any phonogram "floats" in the frequency range. Especially if loudspeakers use efficient and inexpensive short-throw speakers, see below. Subjectively, when listening, experts unequivocally give preference to speakers with frequency response at midrange, smoothly changing over the frequency range within 10 dB in front of one that has 3 dips or "bumps" of 6 dB. Therefore, when designing and making an AU, you need to carefully check at every step: will the frequency response on the midrange not "zagorbat" from this?

A note, speaking of bass: rocker anecdote. So, a young promising group broke through to the prestigious festival. In half an hour they will go out, and they are already backstage, worried, waiting, but the bassist went on a spree somewhere. 10 minutes before the exit - he is not, 5 minutes - also not. They wave at the exit, but still there is no bass player. What to do? Well, let's play without bass. Absenteeism is an instant career ruin forever. We played without bass, it’s clear how. They wander to the service exit, spit, swear. Lo and behold - a bass player, screwy, with two chicks. They are to him - oh you, goat, do you at least understand how you threw us ?! Where were you?! - Yes, I decided to listen in the hall. - And what did you hear there? - Dude, no bass - sucks!

LF

In music, bass is like a foundation for a home. And in exactly the same way, the "zero cycle" of electroacoustics is the most difficult, complex and responsible one. The audibility of sound depends on the energy flux of the sound wave, which depends on the square frequency. Therefore, the bass is heard worst of all, see fig. with curves of equal loudness. To "pump" energy into the woofer, powerful speakers and UMZCH are needed; in fact, more than half of the amplifier's power is spent on bass. But at high powers, the likelihood of the occurrence of NI increases, the strongest and, of course, the audible components of the spectrum of which from the bass will fall exactly on the best audible midrange.

LF “pumping” is further complicated by the fact that the dimensions of the HH and the entire AS are small compared to the LF wavelengths. Any sound source gives it energy the better, the larger its size relative to the length of the sound wave. Acoustic efficiency of the woofer speakers - units and fractions of a percent. Therefore, most of the work and hassle of creating a speaker boils down to making it reproduce bass better. But let us remind you again: do not forget to control the purity of the midrange as much as possible! Actually, the creation of the LF path of the speaker boils down to:

Determination of the required electrical power of the LF GG.
Selecting the LF HG suitable for the listening environment.
Selection of the acoustic design (body structure) optimal for the selected LF GG.
Proper manufacturing in suitable material.

Power

Sound recoil in dB (characteristic sensitivity) is indicated in the speaker's passport. It is measured in a sound-measuring 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 metering board (standard acoustic screen, see the figure on the right) and an electric power of 1 W is supplied (0.1 W for GG with a power less than 3 W) at a frequency of 1000 Hz (200 Hz, 5000 Hz). Theoretically, from 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 HG. But in fact, accounting for local acoustics is so complicated and ambiguous that specialists rarely fool with it.

Note: The HG for measurements is displaced from the center of the screen in order to avoid the interference of sound waves from the front and rear radiating surfaces. The material of the screen is usually a cake of 5 layers of 3-ply pine plywood without sanding on casein glue, 3 mm thick and 4 spacers between them made of natural felt 2 mm thick. All is glued together also with casein or PVA.

It is much easier to go from the existing conditions for the technical sounding of slightly noisy premises, with corrections for the dynamics and frequency range of Hi-Fi, especially since the results obtained in this case are in better agreement with the known empirical data and expert estimates. Then for the initial Hi-Fi you need, 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 consider the actual listening environment. Hundred watt speakers, capable of operating at microwatt levels, are monstrously 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 "micro-whispers" on the quietest pianissimo in any living room will not be heard (see above about the levels of natural noise). Therefore, we increase the obtained values by two or three times in order to "tear off" what is being listened to from the background noise. 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 go from nominal power to peak (musical) power. The "juice" of a sound depends primarily on the dynamics of its volume. THD HG at loudness peaks should not exceed its value for Hi-Fi by a class lower than the chosen one; for the initial Hi-Fi, we take 3% at the peak of THD. In the trade specifications for Hi-Fi speakers, it is the peak power that is indicated as more significant. According to the Soviet-Russian method, 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 their peak receive 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 to promote their THD and evenness of the frequency response, here they really have something to be proud of. Yes, that's just an ordinary foreign citizen will not understand such difficulties, and if the speaker is covered with "180W", "250W", "320W", it's really cool. In reality, the speaker runs "from there" in the sound meter give their peaks in 3.2-3.7 denominations. Which is understandable, since this ratio is justified physiologically, i.e. the structure of our ears with you. Conclusion - aiming at the western GG, go to the corporate website, look for the rated power there and multiply by 3.33.

Note 9, about the designation of the peak and the nominal: in Russia, according to the old system, the numbers in front of the letters in the designation of the speaker indicated its nominal power, and now they give the peak. But at the same time the root with the designation suffix was changed. Therefore, one and the same speaker can be designated in completely different ways, see examples below. Look for the truth from reference sources or on Yandex. There, whatever designation you enter, the results will contain a new one, and next to it in parentheses the old one.

In the end, we get for a room up to 12 sq. m peak for an initial hi-fi at 15W, a basic one at 30W and a high one at 55W. These are the smallest acceptable values; to take GG two or three times more powerful, it will be better, if only symphonic classics and very serious jazz are not listened to. For them, it is advisable to limit the power to 1.2-1.5 from the minimum, otherwise wheezing is possible at loudness peaks.

You can get around even easier by focusing on proven prototypes. For initial Hi-Fi in a room up to 20 sq. m fit 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 speaker S-30B. For decades, these speakers have been regularly and very well "singing" in apartments, cafes and just on the street. Shabby utterly, but they keep the sound.

The S-30B filtering circuit (without overload indication) is shown in Fig. left. Minor revision was made to reduce losses in the coils and the ability to fit different LF GG; if desired, the 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 manufacturing of filter coils. No precision parts are required for this defiltration; +/– 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 rear 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, you can use other GGs that are suitable in power and resistance. One condition: the highest reproducible frequency (UHF) of the LF GG at a level of –20 dB should be at least 7 kHz, and the lowest reproducible frequency (LHF) of the HF GG at the same level - not higher than 3 kHz. By shifting and pushing L1 and L2, it is possible to slightly correct the frequency response in the crossover frequency region (5 kHz), without resorting to such complexities as the Zobel filter, which can also increase transient distortions. Capacitors - film capacitors with PET or fluoroplastic insulation and coated plates (MKP) К78 or К73-16; in extreme cases - K73-11. Resistors - metal film (MOX). Wires - audio from oxygen-free copper with a cross-section of 2.5 sq. mm. Installation - soldered only. In fig. the right shows what the original S-30B filtering looks like (with an overload indication circuit), and Fig. below on the left is a 2-way filtering scheme popular abroad without magnetic coupling between the coils (which is why their polarity is not indicated). On the right in the same place, just in case, there is a 3-way filtering of the Soviet AS S-90 (35AS-212).

About wires

Special audio lines are not a product of mass psychosis or 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 oxide film forms on the metal crystallites, literally into a molecule, 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 copper only in a specially equipped laboratory.

Loudspeakers

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

Getting acquainted with electroacoustics, to know how the speakers are arranged and work in acoustic systems, you need the following. The driver of the speaker is a thin coil of wire that vibrates in the annular gap of the magnetic system under the influence of an audio frequency current. The coil is rigidly connected to the actual sound emitter into space - a diffuser (for LF, MF, sometimes HF) or a thin, very light and rigid dome diaphragm (for HF, rarely - for MF). The efficiency of sound radiation strongly depends on the diameter of the IZ; more precisely - from its relation to the wavelength of the emitted frequency, but at the same time, with an increase in the diameter of the IZ, the likelihood of the occurrence of nonlinear distortions (NI) of sound due to the elasticity of the IZ material also increases; more precisely - not of its infinite rigidity. They struggle with NI in IZ, performing 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 case by separate flexible suspensions. The cone configuration is a thin-walled hollow cone with apex facing the coil. The coil suspension holds the top of the diffuser at the same time, i.e. its suspension is double. The generatrix of the cone can be rectilinear, parabolic, exponential and hyperbolic. The steeper the cone of the diffuser converges to the apex, the higher the recoil and less IR of the speaker, but at the same time its frequency range narrows and the radiation directivity increases (the directional pattern of the antenna pattern narrows). Narrowing the DN 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 dramatically reduces the SOI GG, tk. the cone suspension is a very noticeable source of NO sound, and the material for the diaphragm can be 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 moving system (PS) of the GG. The PS has a frequency of its own mechanical resonance Fr, at which the mobility of the PS increases sharply, and the quality factor Q. If Q> 1, then the speaker without a properly selected and performed acoustic design (see below) on Fr will wheeze at a power less than the nominal, not that peak, this is the so-called. locking the GG. Locking does not apply to distortions, since is a design and production defect. If 0.7

The efficiency of the transfer from the energy of an electric signal to sound waves in air is determined by the instantaneous acceleration of the diffuser / diaphragm (who is familiar with calculus - the second derivative of its time displacement), since air is easily compressible and very fluid. The instantaneous acceleration of the coil pushing / pulling the diffuser / diaphragm should be slightly higher, otherwise it will not "swing" the IZ. Several, but not much. Otherwise, the coil will bend and vibrate the emitter, which will lead to the appearance of NI. This is the so-called membrane effect, in which longitudinal elastic waves propagate in the material of the diffuser / diaphragm. 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 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 fits within the norm for a given Hi-Fi class.

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

At frequencies up to Fр, the membrane effect is never manifested, this is the so-called. piston mode of operation of the GG - the diffuser / diaphragm simply go back and forth. Higher in frequency, the heavy diffuser no longer keeps up with the coil, membrane radiation begins and everything is amplified. At a certain frequency, the speaker begins to emit only as a flexible membrane: at the junction with the suspension, its diffuser is already stationary. At 0.7

The membrane effect dramatically improves the yield of HG, because the instantaneous accelerations of the vibrating sections of the IZ surface are very large. This circumstance is widely used by HF and partly MF HG designers, whose distortion spectrum immediately goes into ultrasound, as well as when designing HF not for Hi-Fi. SOI HG with a membrane effect and the evenness of the frequency response of AC with them strongly depend on the mode of the membrane. At the zero mode, when the entire IZ surface trembles as if to itself in time, Hi-Fi up to the middle inclusive can be achieved at low frequencies, see below.

Note: the frequency at which the HH passes 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 GG (simply - "piston"; in English woofers, barking) are made with a relatively small, thick, heavy and hard anti-acoustics diffuser on a very soft latex suspension, see item 1 in Fig. Then Fр turns out to be 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 the LF waves are long, all this time the diffuser in the piston mode must move with acceleration, and therefore the diffuser travel becomes long. Low frequencies are not reproduced without acoustic design, 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 the so-called. connected air, for "swinging" which requires a significant effort (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 HG has to be made very powerful.

Despite all the tricks, the recoil of piston GGs is small, tk. it is impossible for the diffuser to develop high acceleration at long low-frequency waves: the elasticity of the air is not enough to receive the given energy. It will spread to the sides, and the speaker will go into locking. To increase the recoil and smoothness of the moving system (to reduce THD at high power levels), the designers go all out - they use differential magnetic systems, with half-scattering, and other exotic things. SOI 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 rated power does not exceed 0.25%, and at peak power - 1%. All this is very good, but the prices are mom, do not worry! $ 1000 for a pair with diffmagnets and re-fill for home acoustics, selected for recoil, resonance frequency and flexibility of the moving system is not the limit.

Note: LF GG with a rheological filling of the magnetic gap are suitable only in the LF links of 3-way speakers, because completely incapable of working in a membrane mode.

Piston gas generators have another serious defect: 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 its peak will rip from the suspension and it will fly out along with the coil. Therefore, it is not possible to 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, speaker cones are usually not held by hand and matches are not inserted into the magnetic gap.

For craftsmen on a note

There is a known "popular" way to increase the recoil of piston GG: to the standard magnetic system from the rear, without altering anything in the dynamics, an additional ring magnet is firmly attached with the repulsive side. It is repulsive, otherwise, when a signal is applied, the coil will immediately be torn off the diffuser. In principle, rewinding the speaker is possible, but very difficult. And never before has a single rewind speaker improved, or at least remained the same.

But this is not actually about that. Enthusiasts of this refinement argue 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 recoil. That's right, but Hi-Fi GG is a very finely balanced system. The recoil actually increases slightly. But here the THD at the peak immediately "jumps" so that the distortions of the sound become clearly audible even to inexperienced listeners. At face value, the sound may even become clearer, but without the Hi-Fi speaker, it's already high-quality.

Leading

So in English (managers) are called MCH GG, tk. it is the midrange that accounts for the overwhelming part of the semantic load of a musical opus. The requirements for the midrange GG for Hi-Fi are much softer, so most of them are made in a traditional design with a large diffuser cast from cellulose pulp together with the suspension, pos. 2. Reviews about midrange GG domed and with metal diffusers are contradictory. Mainly the tone prevails, they say, the sound is harsh. Lovers of the classics complain that the bowed ones squeal from the non-paper speakers. The sound of the midrange GG with plastic cones is recognized by almost everyone as dull and at the same time harsh.

The diffuser stroke of the MF GG is made short, because its diameter is comparable to the MF wavelengths and the transfer of energy into the air is not difficult. To increase the attenuation of elastic waves in the diffuser and, accordingly, to reduce the NI along with the expansion of the dynamic range, finely chopped silk fibers are added to the mass for casting the Hi-Fi midrange diffuser, 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 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 cone material of almost all good speakers, and is a versatile way to reduce THD.

Tweets

In our opinion - tweeters. As you may have guessed, these are tweeters, HF GG. It is written with one t, this is not the name of a social network for gossip. It would be generally simple to make a good "buzzer" 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 of magnitude 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 "clue" 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: domed ones are universal, and for fans of the classics, who require necessarily "singing" soft tops, diffusers are more suitable. It is better to take these ellipticals and put them in the AU, orienting their long axis vertically. Then the speaker's DN in the horizontal plane will be wider, and the stereo zone will be larger. There is also an HF GG with a built-in horn on sale. Their power can be taken in 0.15-0.2 of the power of the low-frequency link. 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 the colloquial nickname for broadband GG (GGS), which does not require filtering of the 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 the GGS is also called coaxial speakers or simply coaxials.

The idea of the GGSh is to give the HF membrane mode to the cone, where it will not do much harm, and let the diffuser on the bass and at the bottom of the midrange work "on the piston", for which the woofer-midrange diffuser is corrugated across. This is how broadband GGs are made for initial, sometimes intermediate Hi-Fi, for example. the mentioned 10GD-36K (10GDSh-1).

The first GGS with an HF cone went on sale in the early 50s, but did not achieve a dominant position in the market. The reason is a tendency to transient distortions and a delay in the attack of sound because the cone dangles and slips from the jolts of the diffuser. Listening to Miguel Ramos playing the Hammond organ through coaxial with a cone is unbearably painful.

Coaxial GGSH with separate excitation of LF-MF and HF emitters, pos. 4, this drawback is deprived. In them, the HF link is driven by a separate coil from its own magnetic system. The HF coil sleeve goes through the LF-MF coil. SS and magnetic systems are located coaxially, i.e. along one axis.

GGS with separate excitation at low frequencies are not inferior to piston GGs 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. Coaxial for high hi-fi costs, as a rule, more expensive than a set of LF-MF + HF, although it is cheaper than LF, MF and HF HG for a 3-way speaker.

Auto

Car speakers formally also belong to coaxial ones, but in reality they are 2-3 separate GGs 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. De-filtering is always built-in, i.e. on the case there are only 2 terminals for connecting wires.

The task of autodynamics is specific: first of all, to "shout out" the noises in the car, so their designers do not particularly struggle with the membrane effect. But the dynamic range of autodynamics for the same reason needs a wide, not less than 70 dB, and their diffusers are made necessarily with silk or other measures to suppress higher membrane modes are used - the speaker should not wheeze even in the car on the go.

As a result, car speakers are, in principle, suitable for Hi-Fi up to average, if you choose a suitable acoustic design for them. In all the speakers described below, you can install autodynamic speakers of a suitable size and power, then you will not need a cutout for HF HG and filtering. One condition: the standard terminals with clamps must be very carefully removed and replaced with lamellas for soldering. Loudspeakers made of modern car loudspeakers allow you to listen to good jazz, rock, even individual works of symphonic music and many chamber ones. Mozart's violin quartets, of course, will not be enough, but very few listen to such dynamic and meaningful opuses. A pair of car 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, is how American radio amateurs have nicknamed small-sized low-power HGs with a very thin and light diffuser, firstly, for the high output - a pair of "frisky" 2-3 W each sounds a room of 20 square meters. m. Secondly - for a hard sound: "high-spirited" work only in the membrane mode.

Producers and sellers do not distinguish "high-spirited" into a special class. they are, in theory, not hi-fi. A speaker is like a speaker in any Chinese radio or cheap computer speakers. However, on "high-spirited" you can make good speakers for a computer, providing Hi-Fi up to average inclusive in the vicinity of the desktop.

The fact is that "frisky" ones are capable of reproducing the entire sound range, you just need to reduce their THD 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 GGs from the Canadian company Edifier with silk. By the way, Edifier is a French word and reads "edifier", not "edifier" in the English manner.

The frequency response of the "frisky" ones is equalized in two ways. Silk removes small bursts / dips, and more hillocks and depressions are eliminated by acoustic design with a free outlet to the atmosphere and a damping antechamber, see fig. See below for an example of such a speaker.

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 back surfaces of the diffuser will immediately converge in antiphase, extinguish each other, and you won't hear bass at all. This is called an acoustic short circuit. It is impossible to simply drown out the speaker from the rear to the woofer: the diffuser will have to strongly compress a small volume of air, which makes the resonance frequency of the PS “jump” so high that the speaker simply cannot reproduce the bass. Hence follows the main task of any acoustic design: either to extinguish the radiation from the rear side of the HG, or to turn it over 180 degrees and in phase to re-emit from the front of the speaker system, at the same time preventing the energy of the diffuser movement from being expended on thermodynamics, i.e. for compression-expansion of air in the speaker cabinet. An additional task is, if possible, to form a spherical sound wave at the output of the speaker, since in this case, the area of the stereo effect is the widest and deepest, and the influence of the room acoustics on the sound of the speakers is the least.

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

The purpose of the acoustic enclosure is to provide the best possible bass reproduction. Strength, stability, appearance - of course. 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 speaker systems, MAC), a phase inverter (FI), passive radiator (PI), horns of forward and backward, quarter-wave (FW) and half-wave (PW) labyrinths.

Built-in acoustics are 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, for a beginner for his first speaker, it is best to opt for the PV maze:

Unlike others, except for PI and PI, the MOV labyrinth allows you to improve bass at frequencies below the natural resonance frequency of the woofer.
Compared to the PI PV, the labyrinth is constructive and easy to set up.
Compared to PI PV, the labyrinth does not require expensive commercially available additional components.
An elbow MW labyrinth (see below) creates a HG sufficient acoustic load, while having a free connection with the atmosphere, which makes it possible to use LF HG with both long and short diffuser travel. Up to replacement in already built speakers. Of course, only a couple. In this case, the emitted wave will be practically spherical.
Unlike all, except for the closed box and the MF labyrinth, the loudspeaker with MF labyrinth is able to smooth the frequency response of the LF GG.
Speakers with a PV labyrinth are structurally easy to stretch into a tall thin column, which makes it easier to place them in small rooms.

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

PV maze

Labyrinth is often considered an acoustic design such as a deep slot (Deep Slot, a type of CV labyrinth), pos. 1 in the figure, and a convolutional return horn (item 2). We will touch upon the horns, and as for the deep slit, it is actually a PAS, an acoustic shutter that provides free communication with the atmosphere, but does not release sound out: the depth of the slit is a quarter of the wavelength of the frequency of its tuning. This can be easily verified by measuring the sound levels ahead of the front of the speaker and in the opening of the slit with the help of a highly directional microphone. Resonance at multiple frequencies is suppressed by lining the slot with a sound absorber. A speaker with a deep slot also dampens any speakers, but increases their resonant frequency, although less than a closed box.

The initial element of the PT of the labyrinth is an open half-wave tube, 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 result. At the frequency response of the PV, the pipe gives a high sharp peak, causing the HG to be locked at the frequency of the Fn tuning. But what is already important - Fn and the frequency of the natural resonance of the ГГ f (which is higher - Fр) are theoretically in no way related to each other, i.e. you can expect to improve bass below f (Fp).

The easiest way to turn a pipe into a labyrinth is to bend it in half, pos. 4. This will not only phase the front to the rear, but also smooth out the resonance peak, since 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, increasing the number of knees (it must be odd), but in fact, using more than 3 knees is very rare - the wave attenuation in the pipe interferes.

In the chamber PV labyrinth (pos. 5), the knees are divided into the so-called. Helmholtz resonators - tapering towards the posterior end of the cavity. This further improves the damping of the HG, smoothes the frequency response, reduces the loss in the labyrinth and increases the radiation efficiency, since the rear exit window (port) of the labyrinth always works with a "back up" from the side of the last chamber. Having partitioned the chambers into intermediate resonators, pos. 6, it is possible to achieve an AFC 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 work of an experienced specialist. Once, 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 get the frequency response under high Hi-Fi, just a couple of cameras on your knee are enough. Drawings of an AU of such a design are given in Fig; on the left - Russian design, on the right - Spanish. Both are very good floor acoustics. “For complete happiness,” it would not hurt the Russian woman to borrow the Spanish stiffness ties supporting the partition (beech sticks with a diameter of 10 mm), and instead give smoothing of the pipe bend.

In both of these speakers, another useful property of the chamber labyrinth manifests itself: its acoustic length is greater than the geometric one, since the sound lingers a little 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 turns out to be 37-45 Hz, depending on the type of LF GG. If the S-30B's filtered speakers are rearranged into such enclosures, the sound changes dramatically. For the better.

The range of excitation power for these speakers is 20-80 W peak. Sound-absorbing lining here and there - sintepon 5-10 mm. Tuning is not always necessary and not difficult: if the bass is muffled, the port is symmetrically covered on both sides with pieces of foam until 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 midrange with a steep attack (midrange control!), For example, a violin.

Jet flow

The chamber labyrinth is successfully combined with the usual twisted one. An example is the Jet Flow desktop speaker system developed by American radio amateurs, which made a splash in the 70s, see Fig. on right. Cabinet width inside - 150-250 mm for speakers 120-220 mm, incl. "Frisky" and autodynamics. Body material - pine, spruce, MDF. No sound absorbing lining or adjustment required. The excitation power range is 5-30 W peak.

Note: there is now confusion with Jet Flow - jet sound transducers are on sale under the same brand.

For high-spirited and computer

It is possible to smooth out the frequency response of autodynamics and "frisky" ones in an ordinary twisted labyrinth by arranging a compression damping (not resonating!) Pre-chamber in front of the entrance to it, indicated by K in Fig. below.

This mini-speaker is intended for the PC to replace the old cheap one. The speakers are the same, but the way they start to sound is amazing. If the diffuser is with silk, otherwise it makes no sense to fence the garden. An additional advantage is the cylindrical body, on which the midrange interference is close to the minimum, it is less only on the spherical body. Working position - with a forward-upward tilt (АС - sound projector). Excitation power - 0.6-3 W nominal. The assembly is carried out in the next. order (glue - PVA):

For children. 9 glue the dust filter (you can use scraps of nylon tights);
Det. 8 and 9 are pasted over with padding polyester (marked in yellow in the figure);
Collect a package of partitions on a screed and spacers;
Sintepon rings are glued in, marked in green;
The package is wrapped, gluing, with Whatman paper to a wall thickness of 8 mm;
Cut the body to size and paste over the pre-chamber (highlighted in red);
Paste children. 3;
After complete drying, they skin, paint, attach a stand, mount the speaker. The wires to it run along the bends of the labyrinth.

About horns

Horn loudspeakers have high output (remember why it is just a horn). The old 10GDSH-1 yells through the horn so that the ears faint, and the neighbors “are happy at the most I can’t,” which is why many people are carried away with horns. Home speakers use convoluted horns as they are less bulky. The return horn is excited by the back radiation of the GG and is similar to the MW labyrinth in that it rotates the phase of the wave by 180 degrees. But otherwise:

Structurally and technologically it is much more complicated, see fig. below.
It does not improve, but on the contrary, spoils the frequency response of the speaker, 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.
Radiation from the horn port is essentially directional, and its wave is rather flat than spherical, so one cannot expect a good stereo effect.
It does not create a significant acoustic load of the HH and at the same time requires significant power for excitation (let us also remember - are they whispering into the negotiating horn). The dynamic range of horn speakers can be extended, at best, to basic Hi-Fi, and piston speakers with a very soft suspension (therefore, good and expensive) have a diffuser that breaks out very often when the HG is installed into the horn.
It gives more overtones than any other type of acoustic design.

Frame

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

Much more important to sound quality is the choice of cabinet material. The ideal option is a musical spruce without knots (they are a source of overtones), but finding its large boards for speakers is unrealistic, because Christmas trees are very knotty trees. As for the plastic speaker enclosures, they sound good only industrial-made solid-cast ones, and amateur homemade products made of transparent polycarbonate, etc., are 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 tight for speakers with natural wood materials: perfectly straight-grained pine without defects is expensive, and other available building and furniture species give overtones. It is best to use MDF. The aforementioned Edifier has long since completely switched to it. The suitability of any other tree for the AU can be determined by the trace. way:

The test is carried out in a quiet room, in which you yourself must first stay in silence for half an hour;
A piece of board approx. 0.5 m is placed on prisms made of steel angle pieces, laid at a distance of 40-45 cm from each other;
The bent knuckle knocks for approx. 10 cm from any of the prisms;
Repeat tapping exactly in the center of the board.

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

DIY shelf acoustics

DIY or do it yourself

Once I decided to put together a high-quality acoustics for sounding a small room, as well as for use as near-field monitors when working with sound on a computer (a hobby). The main requirement is adequate sound in relation to the source. Not that the "lows sausage" or "cymbals rang", but an adequate natural sound. So, we collect high-quality "shelf books".

Number of stripes

In theory, the ideal system is single-lane. But, like everything ideal, such a system does not exist in nature. Yes, there are very high-quality broadband speakers for the same Visaton, but for some reason all well-known manufacturers make two-way shelf systems. And when it comes to the floor version, then 3 stripes are not uncommon. There was no particular question here - the classic two-way version: LF and HF.

Speaker selection

The main requirement for the speakers is the optimal price / quality ratio. Those. it doesn't have to be "cheap" for 500 rubles, but also not a mind-blowing "high-end" for $ 1000. Besides, I was in no hurry. The idea to put together "polochniki" with my own hands came a long time ago, and in advance I threw the bait to my good friend, the "sick" sound, with whom we have been constantly and fruitfully communicating on this topic for a long time.

The first to appear were HF - Vifa XT19SD-00/04 ring-rad. These are high quality 4-ohm "squeaks" that are quite popular among audiophiles. It was planned for one set, but for some reason did not go and ended up in my set.

The LFs were the second to arrive. 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 editing, and lonely woofers were not needed by themselves. The 4-ohm 5.5 "midbass housed in a die-cast aluminum basket were purchased immediately.

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

Active / passive?

Each option has its own pros and cons. First, you need to take into account the compactness of the speakers themselves and the associated difficulties in layout in a limited space. And it makes no sense to mount 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 one in each case), then it will turn out to be more expensive than the acoustics itself. Plus, I already had an amplifier. But in any case, I am for the scheme - passive acoustics + amplifier, it is more universal.

Calculation of the dimensions of the case

We have decided on the speakers, now it is necessary to understand which case is optimal for them. Dimensions are based on the sound characteristics of the woofer. There are no recommendations on the manufacturer's website, tk. 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 dude comes to the rescue with a special stand. As a result of laboratory tests, we obtain the calculated size of the case 310 x 210 x 270 mm. In the course of measurements, the parameters of the phase inverter were also calculated.

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

Body material

In my opinion, the most optimal material for the case is MDF. It is acoustically neutral, and also slightly better in performance than particle board. Plywood is also good, but quality plywood is not easy to find and is more expensive and more difficult to process. A 22mm MDF sheet was chosen as the starting material for the body. In principle, the standard 18-20mm is quite enough, but I decided to do a little with a margin. Rigidity is never superfluous.

Body construction and design

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

So design. The speakers should look at least no worse than the "industrial" ones, so that there is no feeling of a club of crazy pens. After all, we do not only high-quality, but also beautiful acoustics. In general, there are practically no beautiful, interesting and at the same time structurally uncomplicated speaker systems. Beautiful acoustics are made by the Italian Sonus Faber, amazingly beautiful - Magico Mini. But all of them are made using precision machines, which by definition do not exist at home. Alternatively, you can order the cases to a good "cabinetmaker" with hands and CNC. Such work will cost, depending on where and what you order, from 10,000 rubles. up to 30 000 rub. together with materials. If the specialist is good, then the speakers will look no worse, if not better than the "store" ones. In this case, I decided that I would completely do everything myself. Therefore, we look at things realistically and make a design without any bevels, curly cuttings, etc. Those. it will be a parallelepiped. Estimated dimensions give a rather pleasant proportion, and proportion in design is already half the battle.

How to design? Although I am connected with design by occupation, I know 3D packages, to put it mildly, superficially. In this case, the program should be more engineering than rendering. Specialized "Kady" for this purpose are heavy and unnecessary. The solution was found quickly enough - freeware SketchUp is more than suitable for this purpose. It is so simple and intuitive that it was fully mastered in about an hour. He can do the main thing: quickly create any shapes, size, use simple textures. I believe that such a program is ideal for "home" purposes. In it, you can easily, for example, design a kitchen or even a small house.

Here is the structure of the case:

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

In general, the options are not bad in appearance, but purely constructively 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 high-quality automotive leatherette. The horn is beautiful in itself, but the woofer has a constructive overlay on the front side of the case, which 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 column itself. We decided on the construction and design.

Instruments

Before moving on to the next stage, I will outline what basic tools are needed to work:

Circular.

Jigsaw.

Grinding machine.

Straight arms.

Without this set, it is better to order cases from a good master.

Saw cut

So, we cut the budget of the MDF sheet. I already wrote that it is better to saw on special machines - it is inexpensive, but it turns out for sure. But since I decided to make the body myself inside and out, then for the purity of the experiment I sawed myself with a manual circular, and small pieces with a jigsaw with a guide. As expected, the perfect cut did not work out. After the cut, the pairs of walls (left-right, front-back, etc.) are installed in pairs, fitted with a grinder and / or electric plane and checked for perpendicularity with a square. And later, during assembly, they are finally adjusted after gluing. Loss of 2-3 mm is insignificant. But all the same, I recommend to cut immediately "on the base", save a lot of time.

Assembling the case

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

Now the hole for the terminal block, as well as a chamfer in order to "sink" it. Initially, according to the project, the terminal block was supposed to be placed at the bottom. But in the process, it became clear that it would not be very convenient to mount the crossover in the center through the woofer hole, so I moved the hole under the terminal block higher, and the place for the crossover - lower.

You can close the box.

Now one of the very crucial 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 system. Why? Because the propagation of sound goes from one source to the listener without time mismatch due to the difference (minuscule) in distance, which is 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 picture "denser". We calculate the holes so that the distance between the edges of the speakers will be about 1 cm. The holes are sawn with a jigsaw with a circular guide.

After the chamfers are removed, we apply the terminal block and the speakers, and then drill the holes for the future screws with a thin drill. Without them, firstly, it can "spread" the MDF itself when screwing in the screws, and secondly, during the final installation, the dynamics will be more difficult to place exactly. I thought for a very long time how to set the dynamics relative to each other, I came to the following scheme:

Screw holes on external surfaces must be repaired before final finishing. I used epoxy. In order not to wait until one surface hardens, I glued each surface with tape and started on the next. When the epoxy is dry, sand it through.

The veneer needs to be protected. I covered 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 in the following way. A strip is cut 20 mm wider than the width of the body and slightly longer than the circumference of the body. It is folded 10 mm on each side, the hem is glued on "special glue 88". Then the strip is glued on the same glue along the circumference to the body. First the bottom (partially), then the back wall, then the top, then the front and again the bottom. In the last step, before gluing, the strip is cut in place and glued end-to-end. I glued all sides at a time, i.e. didn't wait for each side to dry. After each side, I made a short pause (the glue sticks fast enough), and started on the next one.

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

Then holes are cut on the terminal block, "woofer" and "buzzer". The skin on the terminal block and HF will sink down, so the diameter of the cutout can be left 5-10 mm less. The leather on the woofer will be pressed with a decorative ring, so you need to trim it so that it is not visible.

Final assembly

The first step is to mount the crossover. Cross - self-made, on a good element base. Air-core coils, buzzer film capacitors and MOX resistors are used. I myself did not solder it, but ordered smart guys.

Now we solder the required pair of wires to the terminal block and fix it on the case. The terminal block and speakers are screwed in with decorative black self-tapping screws with an asterisk head. Similar self-tapping screws are used to screw on the overlay on the "squeaky", so it would be logical to use the same for the rest. The back wall is ready.

Midbass must be slipped under the skin, and pressed on top with a decorative ring. We solder the remaining pair of wires and mount the speaker.

Everything? Everything. We fasten the acoustic cable to the terminal block and start testing.

Testing

The system was tested in the following configurations:

1. Receiver Sherwood VR-758R + acoustics.

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

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

A little about the configurations themselves. I personally think that at the moment the ideal home music center is: computer + USB-DAC + amplifier + acoustics. Sound in digital without distortion is removed via USB and fed to a high-quality DAC, from which it is transmitted to a high-quality amplifier and then to acoustics. In such a chain, the amount of distortion is minimal. In addition, you can use completely different phonograms: 44000/16, 48000/24, 96000/24, etc. Everything is limited by the capabilities of the driver and DAC. Receivers in this regard are less flexible and outdated in advance. The size of modern hard drives allows you to store almost the entire media library on them. And the tendency to subscribe to Internet content can be abolished, too, although this is not the near future and is far from suitable for everyone.

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

1. Adequate and natural sound. What is recorded is reproduced. There are no distortions in any direction. As I wanted.

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

3. Well-readable bass for this size. Of course, you cannot fully appreciate organ music on bookshelf speakers (it is generally difficult to evaluate it on acoustics), but most of the material “digests” without problems. It is difficult to expect more from such babies.

4. Very good elaboration of details. Every instrument is heard. Even with a rich sound picture and a decent volume, the sound does not go into a mess (the amplifier plays an important role here).

5. I want to make it louder;) Ie. acoustics does not yell, but plays smoothly. Although here, too, is not a small merit of the amplifier itself, tk. as the load increases, a good amplifier remains linear.

6. Long listening does not hurt your head. For me personally, this often happens, but here he plays all day and at least that.

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 peculiarities of the location of the speakers in the cabin. Namely, I read about this kit that its midbasses are more universal in this regard. Which actually proved to be true. You can sit in the center in front of the speakers, you can stand side by side to them - the sound is excellent. There is dependence, but very small.

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

First, a very high quality Unicorn DAC was used.

Secondly, the “self-made amplifier” is the know-how of one sensible Togliatti “sound engineer”. Here it is in a nice little aluminum case:

In a nutshell, we managed to find a circuit solution in which the amplifier retains its characteristics when the volume changes, i.e. does not distort 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 loudspeakers to life, i.e. made them sound like they should sound. By the way, some industrial amplifiers (in particular, the rather good Xindak itself) were reworked according to this scheme, and they had a "second wind".

Have you compared acoustics to something else, you ask? Yes, for example with ProAC Studio 110 - this is a fairly high-quality shelf acoustics, here's a little about them. We compared, realized that they sound exactly no worse. Proaks may have a slightly less dependence of sound on the position of the listener due to the specific placement of the inverter and the "buzzer", there they somehow cleverly calculated all this. And the rest is absolutely no worse, even I personally liked my homemade products more, but we will write it off as subjectivity;) I also wore headphones (quite good Koss) and compared them in panorama, tops and bottoms. Absolutely identical sound. Even at the bottom. In general, the delight is complete.

Costing by materials

MF / LF speakers (pair): 3,000 rubles.

HF speakers (pair): 3,000 rubles.

Crossover (pair): 3,000r.

Sintepon: 160r.

Terminal (terminal block): 700r.

Screws: 80r.

MDF sheet, 22mm: 2 750 rub.

Scotch tape: 30 rub.

PVA: 120r.

Special glue 88: 120 rub.

Vibration isolation: 200r.

Figured overlay ring: 500r.

Cable: 500r.

Total: 14 160r.

Some materials were or got free of charge, and are not taken into account here, respectively.

In custody

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

The quality of the soundtrack.

A device for playing a phonogram.

Digital-to-analog converter.

Signal amplifier.

Wires.

Speakers installed in the speaker cabinet.

Correctly designed for speakers and well-assembled enclosures.

Diagram and kit for the crossover.

This is a basic list, but not a complete one.

It is wrong to think that the main thing is the amplifier, or the main thing - the wires, or the main thing - the speakers. A home music system is like an orchestra. And if in this orchestra someone is bad, and someone is brilliant to play, then on the whole it will turn out to be average. Or, as stated in a very accurate example: if you mix a barrel of shit with a barrel of jam, you get two barrels of shit.

There is also another extreme. A good system costs fabulous money. This means that each component should cost half a million. And phonograms should be exclusively in Super Audio CD or on branded records. Like a closed society of elite audiophiles. It's all bullshit.

I came to the conclusion that it is quite possible to assemble your own relatively budgetary system, which is described in one word "Sounds". And if, due to the peculiarities, it is better to use real-life solutions as a DAC or amplifier, of which there are a lot now. A properly made (independently or to order) speaker system will sound better than a “branded” one purchased for the same money. Almost all components can now be ordered online. Moreover, many manufacturers publish cabinet diagrams for their respective speakers. There is a lot of software for calculating the parameters of the enclosures. There are many specialized forums online, and offline there are people with hands. Of course, it is impossible to be a specialist 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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I want to tell you about the Sony neodymium dynamic heads I purchased, made in Vietnam. The Vietnamese are generally great - they do very high-quality things, I always give them preference when shopping. Who does not know, neodymium is such a magnet that is distinguished by its low weight and high power, which is especially important for manufacturers of home acoustics. In voice coils, neodymium is responsible for the transmission of the frequency range, and therefore for the purity of the sound and its saturation. All these qualities are present in my speakers, which cost me only 750 rubles. - true for the promotion, as the last product. The declared peak power of these 3.5 inch loudspeakers is up to 200 watts :-) In Russia, as far as I know, the power differs from both China and Western manufacturers. However, they work perfectly with a 2 x 50 watt amplifier.

Speaker design

So, the goal was to make a home-made case for them, which would provide maximum bass transmission and had a minimum size, so all these abstruse Internet programs would not suit me for calculating the speaker case.

I designed the speaker cabinet so that the sound bounces off the cabinet wall and then off the magnet and exits through a fairly large phase inverter.

Believe it or not, the bass turned out to be quite impressive at this size (h, w, d - 115 x 115 x 130 mm.). So that there was no unnecessary "knocking on a piece of wood" effect, I pasted over the inner walls of the case with mineral wool.

After everything was done, it remained to attach the legs to the new columns, and since they are homemade, I also decided to make the legs myself, and not buy.

I made oval-shaped depressions in the plasticine, filled it with epoxy glue and, after hardening, leveled it with a file in height. I thought to put an LED in each leg - it would be very unusual, but this is an extra pair of wires, in general I did not.

These speakers play the role of computer speakers for me, but you can use them as rear speakers in a cinema, or if you put them together (they fit perfectly in size), you get a front speaker. That's all, see what happened in the photo. Especially for - Valery K.

Discuss the article SIMPLE DIY ACOUSTIC SPEAKERS

Before a detailed consideration of the problem, we outline the range of tasks, knowing the ultimate goal, it will be easier to choose the right direction. Making speaker systems with your own hands is an infrequent case. It is practiced by pros, novice musicians, when store options do not suit. The problem arises of embedding into furniture or high-quality listening to existing media. These are typical examples, which are solved by a set of generally accepted methods. We will deal with the consideration. We do not recommend flipping the speaker device diagonally, delve into it!

The device of acoustic systems

There is no chance of making a speaker system yourself without understanding the theory. Music lovers should be aware that the biological species Homo Sapiens hears sound vibrations of frequencies from 16 to 20,000 Hz with the inner ear. When it comes to classic masterpieces, the range is high. The lower edge is 40 Hz, the upper edge is 20,000 Hz (20 kHz). The physical meaning of this fact is that not all speakers are able to reproduce the full spectrum at once. Relatively slow frequencies are better suited for massive subwoofers, and squealing at the lower boundary is reproduced by smaller loudspeakers. It is clear that for most people this does not mean anything. And even if part of the signal is lost, it will not be reproduced, no one will notice it.

We believe that those who set the goal of making an independent speaker system should critically evaluate the sound. It will be useful to know that a good speaker has two or more speakers in order to be able to reflect the sound of a wide band from the audible spectrum. But the subwoofer, even in complex systems, is one. This is due to the fact that low frequencies make the environment vibrate, penetrating even through walls. It becomes unclear where the bass is coming from. Consequently, there is one low-frequency speaker - a subwoofer. But as for other things, the person will confidently say from which direction this or that special effect came (the ultrasound beam is blocked by the palm).

In connection with the above, we will carry out the division of the acoustic systems:

Sound in Mono format is unpopular, so we avoid touching on historical excursions.
Stereo sound is provided by two channels. Both contain low and high frequencies. Equivalent speakers with a pair of speakers (bass and squeak) are better suited.
Sound Around is distinguished by the presence of more channels that create a surround sound effect. We avoid getting carried away with subtleties, traditionally 5 speakers plus a subwoofer convey the range to music lovers. The design is diverse. Research is ongoing to improve the transmission quality of acoustics. The traditional arrangement is as follows: in the four corners of the room (roughly speaking) along the column, the subwoofer is on the floor to the left or in the center, the front speaker is placed under the TV. The latter, in any case, is supplied with two or more speakers.

It is important to create the right enclosure for each speaker. Low frequencies will require a wooden resonator, for the upper end of the range it does not matter. In the first case, the sides of the box serve as additional emitters. You will find a video that demonstrates the overall dimensions corresponding to the wavelengths of low frequencies in science, it practically remains to copy ready-made structures, the topic is devoid of useful literature.

The circle of tasks is outlined, readers understand - a homemade acoustic system is built with the following elements:

a set of speakers of frequencies according to the number of channels;
plywood, veneer, body boards;
decorative elements, paint, varnish, stain.

Acoustics design

Initially, we select the number of columns, type, location. Obviously, to manufacture in a larger number than a home theater has channels is an unreasonable tactical move. Two speakers are enough for a cassette recorder. There will be at least six cases for the home theater (there will be more speakers). According to the needs, accessories are built into furniture, the quality of low frequency reproduction is lame. Now the question of the choice of speakers: in the publication by Naidenko, Karpov, the nomenclature is given:

Low frequencies - head CA21RE (H397) 8 inches landing.
Mid range - 5 "MP14RCY / P (H522) head.
Treble - 27TDC (H1149) head 27mm.

They gave the basic principles of designing acoustic systems, proposed an electrical circuit for a filter that splits the flow into two parts (the above is a list of three subbands), gave the name of purchased speakers that solve the problem of creating two stereo speakers. We avoid repeating ourselves, readers can take the trouble to look through the section, find specific titles.

The next question will be the filter. We believe National Semiconductor will not be offended if we screen a drawing of Ridiko's translation amplifier. The figure shows an active filter with a power supply of +15, -15 volts, 5 microcircuits of the same type (operational amplifiers), the cutoff frequency of the subbands is calculated by the formula shown in the image (duplicated in text):

P is the number Pi known to schoolchildren (3.14); R, C - resistor and capacitance values. In the figure, R = 24 kOhm, C is hushed up.

Active filter powered by electrical current

Taking into account the capabilities of the selected speakers, the reader will be able to choose the parameter. The characteristics of the column's playback strip are taken, the overlap joint between them is located, the cutoff frequency is placed there. Thanks to the formula, we calculate the value of the capacity. Avoid touching the resistance rating, the reason: it can (controversial fact) set the operating point of the amplifier, the transmission coefficient. On the frequency response given in the translation, which we omit, the boundary is 1 kHz. Let's calculate the capacity of the specified case:

C = 1 / 2P Rf = 1/2 x 3.14 x 24000 x 1000 = 6.6 pF.

Not so hot what a large capacity, it is selected from the condition of the maximum allowable voltage. In a circuit with +15 and -15 V sources, there is hardly a nominal value that exceeds the total level (30 volts), take a breakdown voltage (the reference book will help) at least 50 volts. Do not try to put in DC electrolytic capacitors, the circuit takes a chance to fly into the air. There is no point in looking for the original circuit of the LM833 chip due to Sisyphean labor. Some readers will find a different chip replacement ... hope for your understanding.

As for the relatively small capacitance of the capacitors (retail and total), the description of the filter says: due to the low impedance of the heads without active components, the ratings would have to be increased. Naturally causing the appearance of distortions due to the presence of electrolytic capacitors, coils with a ferromagnetic core. Feel free to move the scaling limit, the overall bandwidth remains the same.

Passive filters will be assembled with their own hands by each trained in soldering, school physics course. In extreme cases, enlist the help of Gonorovsky, the subtleties of signal transmission through radio-electronic lines with nonlinear properties are nowhere better described. The above material interested the authors with low and high frequency filters. Those who wish to divide the signal into three parts should read the works that reveal the basis of bandpass filters. The maximum allowable (or breakdown) voltage will be negligible, the rating will become significant. To match the mentioned electrolytic capacitors with a capacity of tens of microfarads (three orders of magnitude higher than those used by an active filter).

Beginners are worried about the issue of obtaining a voltage of +15, -15 V to power the speaker systems. Wind up the transformer (example was given, PC program Trans50Hz), supply a full-wave rectifier (diode bridge), filter, enjoy. Finally, buy an active or passive filter. This little thing is called a crossover, carefully select the speakers, correlate the ranges more precisely with the filter parameters.

There are many calculators on the internet for passive speaker crossovers (http://ccs.exl.info/calc_cr.html). The calculation program accepts the input impedances of the speakers, the division frequency as the initial numbers. Enter the data, the robot will quickly supply capacitance and inductance values. On the given page, set the filter type (Bessel, Butterworth, Linkwitz-Riley). In our opinion, a task for the pros. The above active stage is formed by 2nd order Butterworth filters (frequency response rate of 12 dB per octave). Regarding the frequency (AFC) characteristics of the system, it is understandable only for professionals. When in doubt, choose the middle ground. In the literal sense, put a daw on the third circle (Bessel).

Acoustics of computer speakers

I had a chance to watch a video on YouTube: the young man announced that he would make a speaker system with his own hands. The lad is talented: he rasprochil the speakers of a personal computer - well, none at all - he brought out God's amplifier with a regulator, put it in a matchbox (the case of the speaker system). Computer speakers are known for poor bass reproduction. The devices themselves are small, lightweight, and secondly, the bourgeois save materials. Where does the bass come from in the speaker system? The young man took ... read on!

Most expensive component of a music center. High-end acoustics cost bypasses a cheap apartment. Repair, assembly of speakers is a good business.

The low-frequency amplifier of the acoustic system will be assembled by an advanced radio amateur, no kulibins are needed. The volume control knob sticks out of the matchbox, the input is on one side, the output is on the other. The speakers of the old speaker system are small. The young man got hold of an old loudspeaker, not fabulous, but solid. From the column of the Soviet era of the acoustic system.

So that the sound does not disturb the air with a squeak, the clever youth put together one inch boards with a box. The speaker of an old speaker system was placed in the size of a mailbox, displaced, as is done by manufacturers of modern home theater subwoofers. It was too lazy to finish the column from the inside with a sound insulator. Anyone who wishes can use batting, another similar material, for the speaker system. Small speakers are placed inside elongated boxes that just contain the loudspeaker at the end. The proud young man connected one speaker channel to two small speakers, the other to one large one. Works.

The young man is a fabulous fellow, does not drink in the gateway, being like his peers, does not spoil future brides in his free time, is busy with business. As one friend used to say: "The younger generation is forgiven for a lack of knowledge and experience, not an excess of impudence, reinforced by indifference."

Improvements

We decided to improve the technique, frankly we hope that the addition will help make the speaker system a little better on its own. Problem? The concept was invented by radio engineers, creators of acoustic systems - frequency. The vibration of the universe has a frequency. They say that even a person's aura is inherent. It is not without reason that each solid speaker accommodates several speakers. Large ones are designed for low frequencies, bass; others are for medium and high. Not only the size, but also the device they have is different. We have already discussed this issue and refer those interested to the written reviews, where the classification of acoustic systems is given, the principles of operation of the most popular ones are revealed.

Computer scientists know a system buzzer that works by interrupting the BIOS, which seems to be capable of producing one sound, but talented programmers wrote elaborate melodies on it, even with an attempt at digital synthesis and voice reproduction. However, if desired, such a tweeter cannot give out a bass.

Why this conversation ... A large speaker should not just be adapted to one of the channels, but a specialization of bass should be awarded. As you know, most modern compositions (we don't take Sound Around) are designed for two channels (stereo playback). It turns out that two identical dynamics (small) play the same notes, the meaning is small. At the same time, bass is lost from the same channel, and high frequencies are lost on a large speaker. How to be? We propose to introduce passive bandpass filters into the circuit, which will help to split the stream into two parts. We take the scheme of a foreign publication for the simple reason that it first caught my eye. Here is a link to the original site chegdomyn.narod.ru. The radio amateur copied it from the book, we apologize to the author for not specifying the source. This is for the simple reason that we do not know it.

So, the picture. The words Woofer and Tweeter are striking at once. As you might guess, this is, respectively, a subwoofer for low frequencies, and a speaker for high frequencies. The music range covers 50-20000 Hz, with the subwoofer having a low frequency band. Radio amateurs can calculate the bandwidth themselves according to well-known formulas; for comparison, the first octave is, as you know, 440 Hz. We believe that for our case, such a division is suitable. I just would like to find two large speakers, one for each channel. We look at the diagram ...

Not exactly a musical scheme. In the position occupied by the system, the voice is filtered. Range 300-3000 Hz. The switch is signed by Narrow, which translates to stripe. To get Wide playback, omit the terminals. Music fans can throw out the Narrow bandpass filter, we recommend that those who surf Skype should avoid a hasty decision. The circuit will completely eliminate the microphone's looping effect, known everywhere: the high-pitched hum due to over-amplification (positive feedback). A valuable effect, even a military man knows the complexities of using a speakerphone. The laptop owner is aware ...

To eliminate the feedback effect, study the question, find at what frequency the system resonates, cut off the excess with a filter. Very comfortably. With regard to popular music, turn off the microphone, take it away from the speakers (in the case of karaoke), and start singing. Let's leave the high and low pass filters unchanged, the products were calculated by unknown Western friends. For those having difficulty reading foreign drawings, we explain, the diagram shows (the Narrow bandpass filter is discarded):

Capacity 4 μF.
Non-inductive resistances R1, R2 with a nominal value of 2.4 ohms, 20 ohms.
Inductance (coil) 0.27 mH.
Resistance R3 8 Ohm.
Capacitor C4 17 uF.

The speakers must match. Tips of the specified site. The subwoofer will be MSM 1853, the squeaker (the word has not been written off) will be PE 270-175. Calculate the bandwidth yourself. The large letter Ω means kΩ - no big deal, change the denomination. As a reminder, capacitors connected in parallel add up like resistors connected in series. In case it is difficult to get suitable denominations. It is unlikely that it will be possible to make the speakers with your own hands, to gain small resistance values in reality. Do not use coils, we cut out plates of nichrome, similar alloys. After manufacturing, the resistor is varnished, no large current is planned, the element should not be protected.

Inductors are easier to wind on your own. It is logical to use an online calculator, after setting the capacity, we get the parameters: the number of turns, diameter, core material, core thickness. Let's give an example, avoiding being unfounded. We visit Yandex, type something like an "online inductance calculator". We get a number of search results. We choose the site we like, we begin to think how to wind the inductance of the speaker system with a nominal value of 0.27 mH. We liked the site coil32.narod.ru, let's get started.

Initial information: inductance 0.27 mH, frame diameter 15 mm, PEL wire 0.2, winding length 40 mm.

The question immediately arises, seeing the calculator where to get the nominal diameter of the insulated wire ... We worked hard, found on the website servomotors.ru a table taken from the reference book, which is given in the review, consider it to your health. The diameter of the copper is 0.2 mm, the insulated conductor is 0.225 mm. We boldly feed the values to the calculator, calculating the required values.

The result is a two-layer coil, the number of turns is 226. The length of the wire was 10.88 meters with a resistance of about 6 ohms. The main parameters have been found, we are starting to wind. A homemade speaker system is made in a handmade case, there is a place to attach a filter. We connect a buzzer to one output, and a subwoofer to the other. A few words about amplification. It may be that the amplifier stage will not pull four speakers. Each circuit is characterized by a certain load capacity, you cannot jump higher. The design of the loudspeaker system is designed with a fixed margin, often an emitter follower is used to match the load. A stage that makes the circuit work, full return to any speaker.

Parting words for novice designers

We believe we have helped readers understand how to properly design a speaker system. Passive elements (capacitors, resistors, inductors) can be obtained and manufactured by everyone. It remains to assemble the speaker case with your own hands. And this, we believe, will not be the case. It is important to understand that music is shaped by a gamut of frequencies cut off by an improperly manufactured device. When you are going to make a speaker system, think about it, look for components. It is important to convey the magnificence of the melody, there will be firm confidence: the work was not in vain. The speaker system will last a long time and will give you joy.

We believe readers will enjoy making speaker systems with their own hands. The time to come is unique. Believe me, at the beginning of the 20th century it was impossible to scoop up tons of information every day. The training took the form of hard painstaking work. I had to rummage through the dusty shelves of libraries. Enjoy the internet. Stradivari impregnated the wood of violins with a unique composition. Violinists of our time continue to choose Italian specimens. Think about it, 30 years have passed, the cart is left behind.

The current generation knows brands of adhesives, names of materials. The necessary items are sold by shops. The USSR deprived people of abundance by providing them with relative stability. Today, the advantage is described by the possibility of inventing unique ways of earning money. A self-taught professional will cut down cabbages everywhere.