How to make a speaker cabinet from plywood. Making Speaker Cabinets: Review of Materials Materials and Tools

They were ordinary horn loudspeakers and did not have a housing as such. Everything changed when speakers with paper cones appeared in the 20s of the 20th century.

Manufacturers began making large cases that housed all the electronics. However, until the 50s, many audio equipment manufacturers did not completely close the speaker cabinets - the back remained open. This was due to the need for cooling electronic components of that time (lamp equipment).

Stone

The most commonly used stones are marble, granite and slate. Slate is the most suitable material for the manufacture of housings: it is quite easy to work with due to its structure and it absorbs vibrations effectively. The main disadvantage is that special tools and stone processing skills are required. To somehow simplify the work, it may make sense to make only the front panel from stone.

It is worth noting that to install stone speakers on a shelf, you may need a mini-crane, and the shelves themselves must be strong enough: the weight of a stone audio speaker reaches 54 kg (for comparison, an OSB speaker weighs about 6 kilograms). Such enclosures seriously improve sound quality, but their cost can be prohibitive.

The speakers are made from a single piece of stone by the guys from Audiomasons. The bodies are carved from limestone and weigh about 18 kilograms. According to the developers, the sound of their product will appeal to even the most sophisticated music lovers.

Plexiglass/glass

You can make a speaker housing out of transparent material - it's really cool when you can see the "insides" of the speaker. Only here it is important to remember that without proper insulation the sound will be terrible. On the other hand, if you add a layer of sound-absorbing material, the transparent case will no longer be transparent.

A good example of high-end acoustic equipment made from glass is the Crystal Cable Arabesque. Cases of Crystal Cable equipment are made in Germany from strips of glass 19 mm thick with polished edges. The parts are fastened together with invisible glue in a vacuum installation to avoid the appearance of air bubbles.

At CES 2010, held in Las Vegas, the updated Arabesque won all three awards in the field of Innovation. “Until now, no equipment manufacturer has been able to achieve true hi-end sound from acoustics made from such a complex material. – wrote the critics. “Crystal Cable has proven that it can be done.”

Laminated timber/wood

Wood makes good cases, but there are some things to consider here: important point: wood has the property of “breathing”, that is, it expands if the air is humid and contracts if the air is dry.

Because wooden block glued on all sides, tension is created in it, which can lead to cracking of the wood. In this case, the housing will lose its acoustic properties.

Metal

Most often, aluminum is used for these purposes, or more precisely, its alloys. They are light and tough. According to a number of experts, aluminum can reduce resonance and improve the transmission of high frequencies in the sound spectrum. All these qualities contribute to the growing interest in aluminum from audio equipment manufacturers, and it is used for the manufacture of all-weather speaker systems.

There is an opinion that manufacturing an all-metal case is not the most good idea. However, it is worth trying to make the top and bottom panels, as well as the stiffening partitions, from aluminum.

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

Column or speaker?

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

Acoustics and electronics

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

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

There are special programs for calculating AC staircase separating filters, for example. JBL Speaker Shop. However, at home, individual tuning of each plug for a specific instance of speakers, firstly, does not affect production costs in serial production. Secondly, replacing the GG in the AC is required only in exceptional cases. This means that you can approach filtering the frequency channels of speakers in an unconventional way:

The frequency of the LF-MF and HF section is taken to be no lower than 6 kHz, otherwise you will not get a sufficiently uniform amplitude-frequency response (AFC) of the entire speaker in the midrange region, which is very bad, see below. In addition, with a high crossover frequency, the filter is inexpensive and compact;
The prototypes for calculating the filter are links and half-links of type K filters, because their phase-frequency characteristics (PFC) are absolutely linear. Without this condition, the frequency response in the crossover frequency region will be significantly uneven and overtones will appear in the sound;
To obtain the initial data for the calculation, you need to measure the impedance (total electrical resistance) of the LF-MF and HF GG at the crossover frequency. The GG indicated in the passport are 4 or 8 Ohms - their active resistance is DC, and the impedance at the crossover frequency will be greater. The impedance is measured quite simply: the GG is connected to an audio frequency generator (AFG), tuned to the crossover frequency, with an output of no weaker than 10 V into a load of 600 Ohms through a resistor of obviously high resistance, for example. 1 kOhm. You can use low-power GZCH and high-fidelity UMZCH. Impedance is determined by the ratio of audio frequency (AF) voltages across the resistor and GG;
The impedance of the low-frequency-mid-frequency link (GG, head) is taken as the characteristic resistance ρн of the low-pass filter (LPF), and the impedance of the HF head is taken as ρв of the high-pass filter (HPF). The fact that they are different is a joke; the output impedance of the UMZCH, which “swings” the speaker, is negligible compared to both;
On the UMZCH side, low-pass filter and reflective-type high-pass filter units are installed so as not to overload the amplifier and not take power away from the associated speaker channel. On the contrary, the absorbing links are turned to the GG so that the return from the filter does not produce overtones. Thus, the low-pass filter and high-pass filter of the speaker will have at least a link with a half-link;
The attenuation of the low-pass filter and high-pass filter at the crossover frequency is taken equal to 3 dB (1.41 times), because The slope of the K-filters is small and uniform. Not 6 dB, as it might seem, because... filters are calculated based on voltage, and the power supplied to the GG depends on the square of it;
Adjusting the filter comes down to “muting” a channel that is too loud. The channel volumes are measured at the crossover frequency using a computer microphone, turning off the HF and LF-MF in turn. The degree of “jamming” is determined as the square root of the channel volume ratio;
Excessive volume of the channel is removed with a pair of resistors: a damping one of fractions or units of Ohm is connected in series with the GG, and in parallel with both of them - a leveling one of greater resistance, so that the impedance of the GG with the resistors remains unchanged.

Explanations for the method

A technically knowledgeable reader may have a question: does your filter work for a complex load? Yes, and in in this case- It's OK. The phase response of K-filters is linear, as stated, and the Hi-Fi UMZCH is an almost ideal voltage source: its output resistance Rout is units and tens of mOhms. Under such conditions, the “reflection” from the GG reactance will partially attenuate in the output absorbing unit/half-unit of the filter, but for the most part it will leak 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 here: if the impedances of the GG and ρ are different, then power circulation will begin in the filter output – GG circuit, causing the bass to become dull, “flat”, the attacks on the midrange to be drawn out, and the highs to become sharp and whistling. Therefore, the impedance of the GG and ρ must be adjusted precisely, and if the GG is replaced, the channel will have to be adjusted again.

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, which is why, for example, analog active filters have never really taken root in telecommunications technology.

What is hi-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 an informal division into classes gradually developed; The numbers in the list indicate, respectively, the range of reproduced frequencies (operating range), the maximum permissible coefficient of nonlinear distortion (THD) at rated power (see below), the minimum permissible dynamic range relative to the room’s own noise (dynamics, the ratio of maximum to minimum volume), maximum permissible unevenness of the frequency response in the midrange and its collapse (decline) at the edges of the operating range:

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

It is curious that high, basic and initial Hi-Fi roughly 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 high-end Hi-Fi “Heavy” because High High Fidelity in English is like butter.

What kind of hi-fi do you need?

Home acoustics for modern apartment or a house with good sound insulation should satisfy the conditions for basic Hi-Fi. A high one there, of course, won’t sound worse, but it will cost a lot more. In block Khrushchev or Brezhnevka, no matter how you isolate them, only professional experts distinguish between initial and basic Hi-Fi. The reasons for such roughening of the requirements for home acoustics are as follows.

Firstly, the full range of sound frequencies is heard by literally a few people in all of humanity. 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 confidently perceive basic Hi-Fi, but 98% of ordinary listeners in a sound-measuring chamber almost never distinguish between initial and basic Hi-Fi.

Secondly, in the most audible region of the midrange, a person dynamically distinguishes sounds in the range of 140 dB, counting from an audibility threshold of 0 dB, equal to the intensity of the sound flux of 1 pW per square meter. m, see fig. on the right are curves of equal loudness. A sound louder than 140 dB is already pain, and then damage to the hearing organs and contusion. An expanded symphony orchestra at the most 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 is capable of “accelerating” to 110 dB; so is the dynamic range of leading jazz bands with symphonic accompaniment. This is the limit of perception, louder than which the sound turns into still tolerable, but already meaningless noise.

Note: rock bands can play louder than 140 dB, which was what Elton John, Freddie Mercury and the Rolling Stones were fond of in their youth. But the dynamics of rock do not exceed 85 dB, because... Rock musicians cannot play the most delicate pianissimo even if they want to - the equipment does not allow it, and there is no rock “in the spirit”. 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 country house on the outskirts of civilization – 20-26 dB. Sanitary standard noise in the library reading room is 32 dB, and the rustling of leaves is fresh wind– 40-45 dB. It is clear from this that the 75dB high hi-fi speakers are more than enough for meaningful listening in a domestic environment; The dynamics of modern mid-level UMZCHs, as a rule, are no worse than 80 dB. In a city apartment, it is almost impossible to distinguish between basic and high Hi-Fi by dynamics.

Note: in a room noisy by more than 26 dB, the frequency range of the selected Hi-Fi can be narrowed to the limit. class, because the masking effect affects the background of indistinct noises, the frequency sensitivity of the ear decreases.

But in order for Hi-Fi to be high-fi, and not “happiness” for “beloved” neighbors and harmful to the owner’s health, it is necessary to ensure the least possible sound distortion, correct reproduction of low frequencies, smooth frequency response in the midrange, and determine what is necessary for sounding a given room AC electrical power. As a rule, there are no problems with HF, because their SOI “go” into the inaudible ultrasonic region; You just need to put a good HF head into the speaker. Here it is enough to note that if you prefer classics and jazz, it is better to take the HF GG with a diffuser with a power of 0.2-0.3 of that of the LF channel, for example. 3GDV-1-8 (2GD-36 in the old way) and the like. If you are “rushed” by hard tops, then the optimal option would be a high-frequency generator with a dome emitter (see below) with a power of 0.3-0.5 of the power of the low-frequency unit; Drumming with brushes is naturally reproduced only by dome tweeters. However, a good dome HF GG is suitable for any music.

Distortions

Sound distortion is possible linear (LI) and nonlinear (NI). Linear distortion is simply a discrepancy between the average volume level and the listening conditions, which is why any UMZCH has a volume control. Expensive 3-way speakers for high Hi-Fi (for example, Soviet AC-30, also known as S-90) often include power attenuators for the midrange and high frequencies in order to more accurately match the frequency response of the speakers to the acoustics of the room.

As for NI, as they say, they are countless 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 sound already in the air) is not completely identical to the shape of the original signal from the primary source. Most of all, the purity, “transparency” and “richness” of the sound are spoiled. NI:

Harmonic – overtones (harmonics) that are multiples of the fundamental frequency of the reproduced sound. They manifest themselves as excessively rumbling bass, sharp and harsh midrange and treble;
Intermodulation (combination) - sums and differences in the frequencies of the components of the spectrum of the original signal. Strong combinational NIs are heard as wheezing, while weak ones that spoil the sound can only be recognized in the laboratory using multi-signal or statistical methods on test phonograms. To the ear, the sound seems clear, but somehow not so;
Transient – “jitter” of the output signal shape during sharp increases/declines of the original signal. They manifest themselves with short wheezing and sobbing, but irregularly, with fluctuations in volume;
Resonant (overtones) - ringing, rattling, muttering;
Frontal (distortion of sound attack) – delaying or, conversely, forcing sudden changes in overall volume. Almost always occur together with transitional ones;
Noise - hum, rustle, hiss;
Irregular (sporadic) – clicks, crackles;
Interference (AI or IFI, so as not to be confused with intermodulation). Characteristic specifically for AS, IFIs do not occur in UMZCH. Very harmful, because are perfectly audible and cannot be eliminated without major alteration of the speakers. See below for more information about FFIs.

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

In addition to interference, AS can produce predominantly NI according to claims. 1, 3, 4 and 5; Clicks and crackles are possible here as a result of poor quality manufacturing. They struggle with transitional and frontal NI in speakers by selecting suitable GGs (see below) and acoustic design for them. Ways to avoid overtones are the rational design of the speaker cabinet and the correct choice of material for it, also see below.

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

The only way to cope with all this disgrace is to hide the NI deeper under the amplifier’s own noise, which, in turn, should be many times lower than the natural noise of the room. It must be said that modern circuitry copes with this task quite successfully: according to current concepts, a UMZCH with 1% THD and –66 dB of noise is “no”, and with 0.06% THD and –80 dB of noise it is quite mediocre.

With harmonic NI speakers, the situation is different. Their spectrum, firstly, like that of tube ULFs, is pure - only overtones without a noticeable admixture of combination frequencies. Secondly, the harmonics of the speakers can be traced, just like those of lamps, no higher than the 4th. Such a spectrum of NI does not noticeably spoil the sound even at a SOI of 0.5-1%, which is confirmed by expert estimates, and the reason for the “dirty” and “sluggish” sound of homemade speakers most often lies in the poor frequency response in the midrange. For your information, if a trumpet player has not properly cleaned the instrument before a concert and during playing does not splash out saliva from the embouchure in a timely manner, then the THD of, say, a trombone, can increase to 2-3%. And that’s okay, they play and the audience likes it.

The conclusion from here is very important and favorable: the range of reproduced frequencies and the intrinsic harmonics of a NI speaker are not parameters that are critical for the quality of the sound it creates. Experts can classify the sound of speakers with 1% or even 1.5% harmonic NI as basic, or even high Hi-Fi, if the appropriate conditions are met. conditions for the dynamics and smoothness of the frequency response.

Interference

IFI is the result of the convergence of sound waves from nearby sources in phase or in antiphase. The result is surges, even to the point of pain in the ears, or dips of almost zero volume at certain frequencies. At one time, the first-born of the Soviet Hi-Fi 10MAS-1 (not 1M!) was urgently discontinued after musicians discovered that this speaker did not reproduce the A of the second octave at all (as far as I remember). At the factory, the prototype was “driven” in a sound meter using a three-signal method, antediluvian even then, and the position of an expert with an ear for music was not on the staffing table. One of the paradoxes of developed socialism.

The probability of IFI occurrence increases sharply with increasing frequency and, accordingly, decreasing sound wavelength, because To do this, the distance between the centers of the emitters must be a multiple of half the wavelength of the reproduced frequency. At midrange and high frequency, the latter varies from a few decimeters to millimeters, so there is no way to install two or several midrange and high frequency generators in the speakers - then IFI cannot be avoided, because the distances between the centers of the GG 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 greater not only than the distance between the GGs, but also the size of the speakers. Therefore, manufacturers and experienced amateurs often increase the power of the speakers and improve the bass by pairing or quadruplet (putting in a quadruplet) the LF GG. However, a beginner should not do this: internal interference of reflected waves “walking” with the speaker itself may occur. To the ear, it manifests itself as resonant NI: it booms, hums, rattles, it is not clear why. So follow the precious rules so as not to go through the entire speaker over and over again to no avail.

Note: You cannot place an odd number of identical GGs in the AS under any circumstances - the IFIs are then 100% guaranteed

midrange

Novice amateurs pay little attention to the reproduction of mid frequencies - they say, any speaker will “sing” them - but in vain. The midrange is heard best; it also contains the original (“correct”) harmonics of the basis of everything – the bass. The unevenness of the frequency response of speakers in the midrange can give very strong combinational NIs that spoil the sound, because the spectrum of any phonogram “floats” across the frequency range. Especially if the speakers use efficient and inexpensive speakers with a short diffuser stroke, see below. Subjectively, when listening, experts clearly prefer speakers with a frequency response in the midrange, smoothly varying across the frequency range within 10 dB over one that has 3 dips or “bumps” of 6 dB each. Therefore, when designing and making speakers, you need to carefully check at every step: will the frequency response on the midrange “bump” from this?

Note, speaking of bass: rocker joke. So, a young promising group broke through to the prestigious festival. Half an hour later they had to go out, and they were already backstage, worried, waiting, but the bassist was on a spree somewhere. 10 minutes before the exit - he’s not there, 5 minutes - he’s not there either. They wave at the exit, but still no bass player. What to do? Well, we'll play without bass. Failure to do so means instant career ruin forever. They played without bass, it’s clear how. They wander towards the service exit, spitting and swearing. Lo and behold, there’s a bass player, a tough guy, with two chicks. They come to him - oh, you goat, do you even understand how you cheated us?!! Where have you been?! - Yes, I decided to listen in the hall. – And what did you hear there? - Dudes, without bass it sucks!

LF

Bass in music is like the foundation for a house. And in the same way, the “zero cycle” of electroacoustics is the most difficult, complex and responsible. The audibility of a sound depends on the energy flow of the sound wave, which depends on the square of the frequency. Therefore, the bass is heard the worst, see fig. with curves of equal volume. To “pump” energy into the low frequencies, powerful speakers and UMZCH are needed; In reality, more than half of the amplifier's power is spent on bass. But at high powers, the probability of the occurrence of NI increases, the strongest and, of course, audible components of the spectrum of which from the bass will fall precisely on the best audible midrange.

“Pumping” NPs is further complicated by the fact that the dimensions of the GG and the entire AS are small compared to the wavelengths of the NPs. Any sound source transfers energy to it the better, the larger its size relative to the sound wavelength. The acoustic efficiency of low-frequency speakers is units and fractions of a percent. Therefore, most of the work and hassle in creating a speaker system comes down to making it reproduce bass frequencies better. But let us remind you once again: do not forget to monitor the purity of the midrange as often as possible! Actually, the creation of a low-frequency speaker path comes down to:

Determination of the required electrical power of the LF GG.
Selecting a low-frequency GG suitable for the given listening conditions.
Selecting the optimal acoustic design (casing design) for the selected low-frequency GG.
Its correct manufacture in a suitable material.

Power

The sound output in dB (characteristic sensitivity) is indicated in the speaker 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-measuring shield (standard acoustic screen, see figure on the right) and electrical power of 1 W is supplied (0.1 W for GG with a power of less than 3 W) at a frequency of 1000 Hz (200 Hz, 5000 Hz). Theoretically, based on 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 generator. But in fact, taking into account local acoustics is so complex and ambiguous that even experts rarely bother with it.

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

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

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

Further, since we need hi-fi, and not just speech intelligibility, we need to move from nominal power to peak (musical) power. The “juice” of a sound depends primarily on the dynamics of its volume. THD GG at loudness peaks should not exceed its value for Hi-Fi in a class below the chosen one; for initial Hi-Fi we take 3% THD at the peak. In trade specifications for Hi-Fi speakers, it is the peak power that is indicated as more significant. According to the Soviet-Russian method, peak power is equal to 3.33 long-term; according to the methods of Western companies, “music” is equal to 5-8 denominations, but - stop for now!

Note: Chinese, Taiwanese, Indian and Korean methods are ignored. For basic (!) Hi-Fi, at their peak they accept a telephone SOI of 6%. But the Philippines, Indonesia and Australia measure their speakers correctly.

The fact is that all Western manufacturers of Hi-Fi GG, without exception, shamelessly overestimate the peak power of their products. It would be better if they promoted their SOI and frequency response flatness, they really have something to be proud of. But the average foreigner will not understand such complexities, but if “180W”, “250W”, “320W” is written on the speaker, that’s really cool. In reality, running the speakers “from there” in a sound meter gives their peaks at 3.2-3.7 nominal values. Which is understandable, because... This ratio is justified physiologically, i.e. the structure of our ears. Conclusion - when targeting Western GGs, go to the company website, look for the rated power there and multiply by 3.33.

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

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

You can do it even simpler by focusing on proven prototypes. For initial Hi-Fi in a room up to 20 sq. m is suitable GG 10GD-36K (10GDSh-1 in the old way), for a tall one - 100GDSh-47-16. They don’t need filtering, these are broadband GGs. With basic Hi-Fi it is more difficult; a suitable broadband speaker cannot be found for it; you need to make a 2-way speaker. Here, at first, the optimal solution is to repeat the electrical part of the old Soviet S-30B speaker. These speakers have been “singing” regularly and very well for decades in apartments, cafes and just on the street. They are extremely shabby, but they keep the sound.

The S-30B filtering diagram (without overload indication) is shown in Fig. left. Minor modifications have been made to reduce losses in the coils and allow adjustment to various low-frequency generators; if desired, taps from L1 can be made more often, within 1/3 of the total number of turns w, counting from the right end of L1 according to the diagram, the fit will be more accurate. On the right are instructions and formulas for independently calculating and manufacturing filter coils. Precision parts are not required for this filtering; deviations in coil inductance by +/–10% also do not noticeably affect the sound. It is advisable to place the R2 engine on the rear wall to quickly adjust the frequency response to the room. The circuit is not very sensitive to the impedance of the speakers (unlike filtering using K-filters), so instead of the ones indicated, you can use other GGs that are suitable in power and resistance. One condition: the highest reproducible frequency (HRF) of the LF GG at the level of –20 dB must be no lower than 7 kHz, and the lowest reproducible frequency (LRF) of the HF GG at the same level - no higher than 3 kHz. By moving and moving L1 and L2, you can slightly correct the frequency response in the crossover frequency region (5 kHz), without resorting to such complexities as a Zobel filter, which can also increase transient distortion. Capacitors – film with insulation made of PET or fluoroplastic and sprayed plates (MKP) K78 or K73-16; as a last resort - K73-11. Resistors are metal film (MOX). Wires – audio from oxygen-free copper with a cross-section of 2.5 square meters. mm. Installation - soldering only. In Fig. on the right is shown what the original filtering of the S-30B looks like (with an overload indication circuit), and in 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 there, just in case, is a 3-way filtering of the Soviet S-90 speaker (35AC-212).

About wires

Special audio cables are not a product of mass psychosis and not a marketing gimmick. The effect, discovered by radio amateurs, has now been confirmed by research and recognized by experts: if there is an admixture of oxygen in the copper of the wire, a thin, literally molecule-sized film of oxide is formed on the crystallites of the metal, from which the sound signal can do anything but improve. This effect is not found in silver, which is why sophisticated audio connoisseurs do not skimp on silver wire: traders shamelessly cheat with copper wires, because... It is possible to distinguish oxygen-free copper from ordinary electrical copper only in a specially equipped laboratory.

Speakers

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

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

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

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

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

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

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

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

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

Woofers

High-quality piston LF GGs (simply “pistons”; in English woofers, barking) are made with a relatively small, thick, heavy and rigid anti-acoustic diffuser on a very soft latex suspension, see position 1 in Fig. Then Fр turns out to be below 40 Hz or even below 30-20 Hz, and Q<0,7. В мембранном режиме поршневые ГГ способны работать до частот 7-8 кГц на нулевой-первой модах.

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

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

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

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

Note to craftsmen

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

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

Presenters

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

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

Note: Silk is added to the cone material of almost all good speakers; it is a universal way to reduce the SOI.

Tweets

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

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

Shiriki

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

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

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

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

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

Auto

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

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

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

Frisky

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

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

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

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

Acoustics

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

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

The purpose of the speaker cabinet with acoustic design is to ensure the best reproduction of low frequencies. Strength, stability, appearance – 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, MAS), a bass reflex (FI), passive radiator (PI), direct and reverse horns, quarter-wave (QW) and half-wave (HF) labyrinths.

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

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

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

PV labyrinth

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

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

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

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

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

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

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

Jet Flow

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

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

For the frisky and the computer

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

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

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

About horns

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

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

Frame

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

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

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

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

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

Acoustic design does not mean decorating the speakers with carvings in an antique style, although this will give the speakers uniqueness, but solving the problems of acoustic short circuit.
The fact is that when the diffuser moves, excess air pressure is formed on one side, and the air is discharged on the other. For sound to occur, it is necessary that air vibrations propagate into space and reach the listener, and in this case the air vibrates around the dynamic head basket and the sound pressure it creates is not very high, especially in the low frequency region:

More details about the principle of operation of the dynamic head HERE.
Methods of breaking the acoustic circuit are called acoustic design, and each of them is designed to make it difficult for air to penetrate from one side of the diffuser to the other.
There are several main options for breaking an acoustic short circuit. The simplest is to use sheet material in the middle of which a hole is cut for the dynamic head. This is called an acoustic screen:

A slightly more complex method is an open box, i.e. drawer without back wall:

Both of the above methods have too little efficiency, so they are practically not used only in cases where “there is no fish and no cancer.”
It is much more effective to use a closed box, and in such speakers special attention is paid to the tightness of the box - any gap in the box will produce overtones, since quite a lot of pressure arises in the box (when the diffuser goes inside the box) and a fairly large vacuum (when the diffuser moves out) :

The next option for acoustic design is a box with a bass reflex:

In this case, this is a rectangular hole located in a strictly calculated location on the front panel of the speaker system. However, this option can also be done using a pipe:

The advantages of these options include increased output at the frequency at which the bass reflex is designed, the main purpose of which is to invert, i.e. change the phase to the opposite. As a result, sound is emitted into space not only by the front part of the diffuser, but also by the rear part, the phase of which is changed by the bass reflex.
A more complex version of acoustic design is an acoustic labyrinth. The essence of this option is that the passages inside the speakers are located in such a way that resonance occurs at a certain frequency and, as a result, a large increase in output at this frequency. The calculations and manufacturing accuracy of such systems should be taken VERY seriously, since there is a high probability of “standing” waves occurring in the labyrinth. In this case, the sound quality will be even worse than that of the option with an acoustic screen:

The horn version allows you to get even greater output at the resonant frequency:

The difference between a horn speaker and a labyrinth speaker is that the direction of sound waves varies according to different laws - the horn either expands conically along its entire length, or exponentially. The labyrinth can have the same window along its entire length, it can expand or, on the contrary, narrow, but always linearly. In addition, for speakers with a labyrinth, both the front and rear parts of the diffuser take part in the work, while for horn speakers, both one and both sides can radiate.
The next acoustic design option is a bandpass or bandpass resonator:

This option differs from all previous ones primarily in that it emits only at the resonance frequency and requires strict adherence to the design dimensions.
The last three options are mainly designed for using a low-frequency dynamic head, while the previous ones are quite suitable for wideband speakers. Therefore, if the acoustic system has, in addition to woofers, others, for example, midrange and HF, then it is not recommended to embed them into the housing with the woofer.
In any case, to calculate the speaker sizes, you will need the characteristics of the dynamic head, in particular the Thiel-Small parameters. If this data is not available, it is necessary to obtain it before calculating the dimensions of the speaker housing. There are quite a lot of descriptions of methods for obtaining these parameters - just use any search engine.
Of course, these are not all types of acoustic design - these are the most popular.
The enclosure dimensions are calculated using special programs for calculating speaker enclosures. Finding them on the Internet, as well as instructions on how to use them, is also not problematic.
When designing speakers, you should take into account some technological features - if the front panel on which the speaker is installed is recessed into the housing, then you will need to make additional ribs into which the front panel will actually rest:

If you don’t want to mess around with the ribs, you can make the front panel so that it rests against the sides of the case, which also strengthens the connection between the front panel and the sides:

All this will give the front panel an additional, more rigid connection with the body.
You should also not forget about the methods of attaching the dynamic head to the front panel and the pitfalls that you may encounter. Mounting the speaker from the outside is most preferable, since it does not mechanically weaken the structure, but this method involves chamfering along the diameter of the dynamic head and sinking the speaker inside the housing so that ALL emitters, bass, midrange, and treble are in the same line. chamfering reduces the mechanical strength of the front panel and its restoration will require an additional ring secured from the inside. The relevance of this ring is the higher, the greater the power expected to be obtained from the speaker being manufactured, and at powers above 150 W it is already 100% necessary:

If necessary, you will need to remove the side chamfers on the ring so that it does not interfere with the front panel of installation into the case itself.
When installing the dynamic head, it is necessary to ensure that there are no gaps. If the chamfer is removed by a machine, the surface turns out to be relatively smooth; all that remains is to sand it. However, at home it is quite difficult to obtain a flat surface. It is not entirely clear what the manufacturers are doing here - it is strongly recommended to install the speaker from the outside, but the sealing rubber on almost all dynamic heads is located for installation from the inside:

To solve sealing problems, you can use door seals - self-adhesive strips of porous rubber, sold in all hardware stores. The sealant is glued along the perimeter of the chamfer and when installing the speaker, it completely fills all the cracks:

If the dynamic head is installed from the inside, then the hole will need to be chamfered to prevent the appearance of standing waves. However, such a chamfer weakens the rigidity at the point where the speaker is attached to the panel (the material is too thin) and this method of fastening is not acceptable for powers above 50 W without additional reinforcement of the structure:

It is advisable to use natural material for the manufacture of speaker cabinets, optimally plywood, but this material is too expensive. Therefore, it is better to use plywood to build speakers of medium and high price categories, using dynamic heads of VERY good quality and power above 100 W.
For the average price category and low powers (up to 50W), you can use fiberboard or MDF (the same as fiberboard, only the thickness and density is greater), but it must be processed and modified, or chipboard.

For powers up to 10 W, plastic is also quite suitable, but also using technological tricks.
The first problem when making speakers from plastic arises when eliminating the chatter of the plastic itself, especially manifested in the centers of the sidewalls. You can get rid of this unpleasant sound by using thicker plastic, or you can glue additional stiffeners. If the plastic is dissolved with dichloritane, then dichloritane with plastic chips dissolved in it can be used to attach the ribs. If the plastic is not dissolved by dichloroethane, then it is better to use epoxy glue, preferably made in Dzerzhinsk. Before gluing, carefully sand the contact areas with coarse sandpaper and do not be afraid that the glue forms beads at the point of contact of the parts to be glued:

For greater efficiency in suppressing overtones of the body, you can “paint” the resulting “baths” in 2-3 layers with anti-gravel - a coating used to cover the underbody of cars to protect against small gravel.

After drying, anti-gravel acquires the properties of rubber and absorbs sound quite well.
When using fiberboard as a material for the manufacture of speakers, it is necessary to determine the required thickness. If the speaker power does not exceed 5 W, then fiberboard can be used in one layer. Before cutting the fiberboard, it is coated on one side with epoxy glue and heated with a hairdryer. Under the influence of temperature, the glue becomes more liquid and impregnates the fiberboard to almost half the thickness. Once the glue has hardened, the resulting material is quite strong, essentially getinax, but on the one hand retains the sound-absorbing properties of fiberboard. You can cut DPV with a jigsaw, and you can glue the workpieces with epoxy glue reinforced with material. To do this, the blanks are folded into the desired structure and secured with any SUPERGLUE. Then strips of strong fabric are cut, in our case it is red silk. The width of the strips should be approximately 3...4 cm. The strips are laid at the joints of the workpieces, covered with epoxy on top, and then “ironed” with a 40...60 W soldering iron. High temperature allows the glue to completely saturate the fabric, and also significantly accelerates the polymerization of the glue. True, during operation a certain amount of smoke is released, so work must be done either outside or under a hood:

If the speaker power is higher than 10 W, but less than 20, then it is better to glue the fiberboard in half - first the sheets are glued together, and then the finished case is assembled:

For powers up to 30...35 W, you will need to fold the fiberboard in three or use 18 mm thick chipboard (unfortunately, 22 mm thick chipboard can only be found in old grannies in the form of old wardrobes made before the 80s). To stiffen the sidewalls, you can use spacers of the "CROSS" type:

For powers up to 50 W, the relevance of using fiberboard is already debatable - it is much easier to work with chipboard, MDF or plywood than to fold fiberboard from 4-5 layers. For this, material with a thickness of 18 mm is suitable, but you will have to use additional bars to ensure a greater connection between the speaker parts:

The speaker can be assembled using self-tapping screws, but since the power is not greater, it can be glued with epoxy glue or PVA, but it is better to buy it not at an office supply store, but at a hardware or construction store. This PVA will be called MOMENT-STOLYAR, water-dispersion glue. Buy on the market Recommended only in summer - after freezing the glue seriously loses its quality. However, to ease your conscience, it is better to screw at least a couple of screws into each block.
When manufacturing speakers, sometimes they make a serious mistake - the mid-HF link is not acoustically protected in any way from the impact of the back side of the woofer cone, which leads to a decrease in the efficiency of the speaker itself, and often the failure of the midrange link - too strong air impacts from the back side of the woofer diffuser lead to the midrange speaker coil being pushed out of the magnetic gap and the coil jamming.
Much more often they forget to subtract the volume of the protective casing of the midrange-high-frequency speakers from the total volume of the speaker; as a result, the internal volume of the speaker is less than necessary and the final characteristics are greatly blurred - the resonant frequency of the phase interferors increases noticeably, which results in unwanted overtones.
When assembling speakers with a power of up to 100 W, you can also use either chipboard or plywood 18 mm thick, although of course it is better to look for material 22 mm thick. To eliminate the occurrence of resonances in the sidewalls of the speaker body, additional support bars are also used through which parts of the speaker are attached. It would not be superfluous to install a “cross” and an additional washer for attaching the woofer dynamic head, as well as treating the speakers from the inside with sound-absorbing materials, for example, pasting with paralon or foam plastic 5-10 mm thick, just do not forget that the pasting will “eat” part of the internal volume and it is necessary to make an adjustment for it when calculating the dimensions of the body.

The best results are obtained with polyurethane foam, since the thickness of the applied layer can be adjusted by the speed at which the foam is released from the can. If the foam is released VERY slowly, then it turns out to be very dense and the increase in volume is not very large. If the foam is released VERY quickly, then it turns out to be much looser, and when it hardens, it greatly increases in volume. If foam is applied to the sides of the case from the front panel, increasing the foam output as it approaches the rear wall, and ensuring a minimum rate of foam output at the front panel, the internal volume of the speaker will take the shape of a pyramid lying on its side. Such tricks make it possible to completely solve the problems of standing waves, since there are no parallel planes inside the speakers, and the unevenness of the frozen foam only enhances the pyramid effect. When using this technology, you should be more careful when calculating the dimensions of the workpieces - the internal volume decreases VERY significantly and this requires a serious increase in the speaker body.

It is recommended to glue the ribs for fastening the sidewalls, in addition to the screed with self-tapping screws, as in the previous version, but there are several more options for adhesive masses:
- epoxy glue mixed with fine sawdust, or, better yet, wood dust;
- MOMENT-JOINER, but before screeding, the applied glue must be allowed to dry a little until it reaches the consistency of butter at room temperature. This will allow you to more completely fill with glue all the irregularities between the speaker parts;
- polyurethane glue, for example MOMENT-CRYSTAL, which also needs to be allowed to dry a little. After assembly, the gluing area must be thoroughly heated with a hairdryer, which will lead to the formation of small bubbles in the adhesive mass, and the mass itself will more tightly fill the unevenness between the contacting parts of the body;
- automotive sealant of domestic production, precisely domestic, since after hardening it is much tougher than imported sealants;
- mounting, polyurethane foam. Before applying it to the parts to be glued, the foam is “released” onto an unnecessary piece of plywood or fiberboard, and then thoroughly mixed with a metal spatula until it “shrinks,” i.e. until you obtain a mass similar in thickness to thick sour cream. After application and screeding, the foam will still expand slightly and completely fill all the irregularities at the point of contact between the speaker parts.
After gluing, the parts should be allowed to dry thoroughly for 20...26 hours.
To increase the volume at the same output power, you can use “double” dynamic heads - parallel or series connections of two identical speakers are used for the low-frequency section. In this case, the total area of the diffusers increases, therefore the speaker can interact with a much larger amount of air, i.e. create greater sound pressure and this makes the subjective loudness much higher:

It should be noted here that the use of a large number of speakers, including for dividing the audio range, begins to introduce some troubles - it is quite difficult to achieve signal phasing in those places where the frequency response of speakers neighboring in the range intersects. Therefore, you should not chase a large number of bands for a homemade speaker - this mess can be very spoiled with such oil.
It is better to make speakers with a power from 100 to 300 W from plywood, and you will have to look for plywood with a thickness of 22 mm. The speaker is also assembled using stiffening bars that are glued. It is better to give the bars the shape of equilateral triangles, where the legs will be attached to the sides, and the hypotenuse will be directed inside the body.
If you cannot find plywood of this thickness, then you can use 8 mm thick plywood glued in three - the final thickness of the material is 24...25 mm. The adhesives are listed above.
As technological advice, we can only recommend first cutting the necessary blanks and only then gluing them, and immediately tightening them with self-tapping screws.
When installing a “cross” inside the AC, which would not be amiss, it is better to round the corners of the tie bars - quite large volumes of air are already moving and turbulence may occur around the right corners of the screeds. It is also recommended to “round” all internal corners using plasticine or applying several layers of thick anti-gravel.
Another type of acoustic design is separate housings for each speaker. These speakers do not use passive filters, and the signal is divided into ranges immediately after the amplifier's volume control. The split signal is then fed to three separate power amplifiers, which each drive their own speakers:

It would be unfair not to mention the “fillers” often used in speakers - small rollers of sound-absorbing material lying inside the speaker. Such rollers make it possible to slightly increase the calculated internal volume of the body, however, in order to correctly manufacture such a “filler” it is necessary to know its acoustic properties. Obtaining the characteristics of the “filler” in a home-made environment is quite problematic, so the only thing left to do is either refuse to use the “filler” or experimentally find out the required volume and the material used (usually fluff wool, batting, sentipon).
At powers above 100 W, it also becomes important to ensure the stability of the speaker cabinet, since quite a lot of work is already being done to move the diffuser and the air is actively “resisting”. It is also advisable to break the mechanical connection between the bottom of the speaker and the floor on which the speaker is installed. For these purposes, they usually use either tripods, which are problematic to make at home, or they use steel spikes screwed into the bottom of the speaker:

At powers above 200 W, it is desirable to strengthen the front panel of the speaker and it is desirable to use materials of different structures, for example, if the front panel is made of plywood, then a sheet of chipboard is glued to the inside, the thickness of which is 1.5-2 times less than the thickness of the panel. This combination of materials ensures the absorption of vibrations in a larger audio range precisely due to the heterogeneity of the materials.
For greater stability of the speaker, its mass can be increased by coating the bottom with polyurethane foam and laying a couple of bricks in it, covering them on top with the same foam. After the foam has hardened, it is better to cut off the irregularities with a stationery cutter. The “stolen” internal volume must be taken into account when calculating the size of the future speaker.
For powers above 200 W, it is better to use combination materials - all speaker parts are glued together from 18 mm chipboard and 18 mm plywood. Plywood is used as the outer layer and chipboard as the inner layer. This trick allows you to save a little - chipboard is much cheaper than plywood. It is advisable to glue the inside of the speaker with sound-absorbing material, for example, triple-sewn batting, double-stitched with quadruple padding (the padding can be double and quadruple), 5...10 mm polystyrene foam. The different structure of tightly glued materials of different structures eliminates the problem of resonance of the body itself.
It is better to additionally tighten the corners with metal corners - this will add rigidity to the structure and protect the corners of the speakers from damage - the speakers are already quite heavy and during transportation various impacts are possible from which the corners most often suffer.

For powers closer to 1000 W, the thickness of the material should already be quite large, for example, two layers of 18 mm plywood plus a layer of 18 mm DPS for a total of 54 mm, and the DPS is glued between the layers of plywood, however, the speakers already move into the category “for sound”, therefore quality can be sacrificed in favor of mobility. Based on this, you can use double 18 mm plywood, installing a “cross” inside.
It is not difficult to notice that with increasing power, the thickness of the speaker walls increases. This is primarily due to the fact that it is necessary to isolate the air moving inside the speaker from the listener. However, we should not forget that the speaker cabinet can also resonate. It is to eliminate this nuisance that it is better to use internal pasting of the housings and minimize the overtones obtained from resonance. It is not difficult to check the resonant frequency of the housing yourself. To do this, you need to tilt the speaker 20...25 degrees and throw a rubber mallet on top of it, from which you first pull out the handle. The tilt of the AC is necessary so that the blow is single and the mallet bounces far to the side.
A microphone attached to the speaker (the membrane hole to the body) and connected to any linear amplifier on the oscilloscope screen will draw both the moment of impact and the aftersound that the body itself gives. The test is, of course, quite crude, since in reality the “shock wave” comes from the inside, and during the experiment from the outside, however, based on the results of this test, one can judge at what frequency the body itself resonates and how quickly attenuation occurs:

An ideal speaker does not cut and the moment of impact fades immediately, almost instantly, but the walls of an ideal speaker consist of concrete 1 cm thick for every watt of power and such a speaker is more suitable for ridicule than for use:

The finishing of the speakers can be very different, there are no strict requirements here. If the body is made of plywood and the pattern is quite attractive, then the body can be sanded and then coated several times with colorless varnish:

You can buy veneer from valuable wood species and cover the speakers with veneer to match the color of the furniture in the room:

Car audio stores sell so-called acoustic fabric, which is synthetic felt. The material adheres well and stretches, which will allow you to finish the speakers at a fairly high level:

Having sanded the body, you can paint it with car paint, just make allowance for the fact that car enamels need to be dried at high temperatures. Therefore, you will have to use a special hardener "IZUR", the mixing proportions are written on the packaging of the hardener, although it is better to add 10-15% more than the suggested proportion:

If the body is carefully sanded and sanded, then it can be covered with a self-adhesive film sold in BOI stores, but this material is quite delicate and should be used if you are sure that the speakers will stand in their place for ten years:

If you plan to frequently transport the speaker system, it will be very useful to provide appropriate handles. This is especially true for small speakers, which you want to take two at once, and for large ones, which simply have a lot of weight.

How to independently assemble an active speaker with increased efficiency at low frequencies is described.

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They were ordinary horn loudspeakers and did not have a housing as such. Everything changed when speakers with paper cones appeared in the 20s of the 20th century.

Manufacturers began making large cases that housed all the electronics. However, until the 50s, many audio equipment manufacturers did not completely close the speaker cabinets - the back remained open. This was due to the need to cool the electronic components of that time (tube equipment).

Stone

The most commonly used stones are marble, granite and slate. Slate is the most suitable material for making cabinets: it is easy to work with due to its structure and it absorbs vibrations effectively. The main disadvantage is that special tools and stone processing skills are required. To somehow simplify the work, it may make sense to make only the front panel from stone.

Plexiglass/glass

Laminated timber/wood

Wood makes good cabinets, but there is an important point to consider here: wood has the ability to “breathe”, that is, it expands if the air is humid and contracts if the air is dry.

Since the wooden block is glued on all sides, tension is created in it, which can lead to cracking of the wood. In this case, the housing will lose its acoustic properties.

Metal

There is an opinion that making an all-metal case is not a good idea. However, it is worth trying to make the top and bottom panels, as well as the stiffening partitions, from aluminum.

Dedicated to those who have free time

We open a popular magazine about good sound and look with pleasure at the elegant images (if not the image) of acoustic systems, and there is something to look at. Powerful towers bristle with speakers in all directions, shine with their varnished sides, crush the parquet with sharp spikes and generally evoke a feeling of deep respect. The only downside they seem to have is, of course, the price. A completely logical question arises: what if you make a copy of a monster yourself? Buying a speaker is not difficult, assembling the housing, even if it is not so beautiful, also, the coils and capacitors can be domestic, carefully soldering 3 parts is a task for a 10th grade school student.

Considering the number of ready-made modules that Ebay offers, making a good amplifier is not much more difficult. What’s not there: switching, speaker protection, A-AB-D class boards, volume controls for every taste, beautiful cases made specifically for audio, handles, legs and transformers - just know, connect. In the next article we will definitely tell you how to assemble your own amplifier, which will not be inferior to most “branded” samples costing up to 60-70 thousand rubles.

You may come across unfamiliar words later in the text. Fortunately, an unknown audiophile came to our aid and left link to your personal archive of information on acoustics and amplifiers, there really is ALL and even more, we strongly recommend that you read it.

What to make it from? Plywood, MDF, chipboard, plastic, solid wood.

The world has seen many strange acoustic structures, for example, made of concrete or cinder block. Still, the above-mentioned wood-based lumber remains the most “in demand”. Let's try to understand which one is “more correct”. The basic rule is - regardless of the material chosen, do not skimp on its quality, that is, price.

First comes the king of modern Hi-Fi and Hi-End industry - MDF, The vast majority of speakers, both expensive and cheap, are made from it. The reason is simple - low cost, ease of processing and finishing, including options with ready-made veneer, and the absence of bright resonances. With proper design, optimal results are guaranteed. We recommend it for use, nothing more to say.

Plastic - the concept is very loose, its “authority” is significantly undermined by cheap Chinese counterfeits, although it has no fewer advantages than any other material. We are passing by the problem of the inaccessible opportunity for an amateur to cast his own blanks from the desired material.

A good material for making an acoustic system enclosure can be Chipboard. Perhaps its main drawback is the many problems with finishing, no matter what you decide: paint, veneer or upholstery. Chipboard has a huge advantage: if you need to do it quickly and very cheaply, you can use a factory-made laminated chipboard (LDSP). In this case, it is unlikely that it will be possible to achieve high aesthetics, but the price and speed will leave all other contenders far behind. If we compare the resonant properties of materials in terms of suitability for speakers, chipboard takes first place, although the difference compared to MDF is small.

Capricious, but invariably desired by “seasoned audiophiles” madam plywood. There are several types of plywood - birch, coniferous, alder, laminated. Why capricious? Any plywood “leads”, that is, when the sheet dries, it changes its geometry, and chips often appear when sawing. It is also not the easiest material to finish if you want to get a “dull” matte color without visible edges, texture, or edges. The reason for enduring this torment is quite controversial: according to “experienced” people, only plywood gives that very living breath that chipboard and MDF “kill”. What I most incomprehensible is the desire to make a body out of “living” plywood and “kill” it with layers of putty, primer, paint, varnish in an attempt to hide the “terrible” joints with veins (layers of plywood), which look at their owner with silent reproach day and night . Options for special impregnation, at least with the same “Danish oil”, are much preferable; these dark “stripes” on the edges of the body are not so scary...

What kind of poverty is this chipboard-MDF? Maybe straight from solid oak, but thicker!? Don't rush to insert the speaker into the first hollow you see. Contrary to expectations array valuable wood does not enrich the sound in proportion to the money invested; moreover, it even requires additional damping compared to cheaper materials. Although its undoubted advantages are the ease of finishing: if the acoustics are assembled carefully, bringing it to a nice eco-look will not be difficult. Instead of increasing the thickness, it is recommended to add (glue) another sheet of less resonant material on the back side, for example, the same MDF, to make a “sandwich”. The most successful option for using the array is in shield-type acoustics, where a beautiful and heavy front panel is required.

Exotic. Often the choice is determined by what is at hand. Just as a bird can masterfully weave all kinds of garbage into its nest, so a music lover drags everything that is in bad shape. You can find on the Internet ideas embodied in plumbing pipes, artificial stone, papier-mâché, cases and cases for musical instruments, primitive building materials, IKEA products, etc., etc.

Where should I put the speaker?

The main task of acoustic design can be formulated in simple language approximately like this: to maximally separate the vibrations emitted by the front side of the speaker diffuser from the same anti-phase vibrations emitted by the rear side of the diffuser. From the point of view of the textbook, the ideal acoustic design is considered to be an infinite screen, such an incredibly huge shield in which the speaker is installed. It’s clear that the words “incredibly huge” do not apply to our home or our salary, so engineers began to look for a way to “minimize” this screen with minimal negative consequences for the sound. This is how all the variety of options turned out, some have gained the most widespread fame on the Internet, and we will consider them in this article.

Just a speaker or housing without housing

It’s hard to imagine that there is such a type of “acoustics”, but, scrolling through the feed of photos on Pinterest on the topic of audio, I increasingly come across clusters of 12-inch speakers that are assembled together without any design and clearly represent a complete unit. Probably, the author’s intention is permeated by the following logic: any housing spoils the sound, an acoustic short circuit is better than wooden shackles, but in order to have at least some “low”, you need to take speakers with the maximum cone area for which you can only afford enough money. If this is your path - no comments.

Shield and “broadband”

They say that those who have tried the tube, full-range speaker and open design will never return to the traditional, transistor-rubber lifestyle. Describing the properties of a shield is not a rewarding task; all the necessary information is in the archive, and for the laziest - on YouTube, where they explain in detail what kind of animal it is and what it is eaten with, for example: .

The biggest advantage of this design is its ease of manufacture. You need a sheet of your favorite material and a jigsaw. The most important criterion that will influence the final sound quality is the cost of the installed dynamic head. The 4a32 speaker has gained unabated popular fame, even such grandees as fostex, sonido, supravox, sica or the visaton B200 itself are left far behind. The saying “size matters” is the best mathematical formula for a shield (the bigger the better). Next come variations of the shield, for example, a shield with folded side walls, a shield in which the low-frequency module is made in the form of a box with a bass reflex, etc. The signature feature of the sound is an “airy” sound with a minimum of resonances, and at the same time a relatively high sound pressure.

PAS – acoustic resistance panel

What if you try to cross a shield and a closed box? You will get a box with a back wall in which many holes are made. The number of holes, their total area in combination with the volume of the box will determine the degree of damping (resistance), the level of low frequencies (the fewer “holes” - the more bass, but also the more “mumbling”). The quantity is selected experimentally, according to taste.

Linear array of emitters, group emitter (GI)

In fact, this subtype of acoustics concerns more the speakers than the design of the cabinet itself. I think you’ve already seen speakers, each of which consists of a large number of identical small, small speakers, or not very small ones, as your budget and living space allow.

According to the electrical diagram, the heads are connected in series, that is, the “plus” of the previous one is connected to the “minus” of the next one, it is possible to combine a series-parallel connection. The number of speakers, in fact, is also limited only by money; common sense, as a rule, by this moment disappears without a trace. Don’t think anything bad about me, I tried such a perversion, I even liked it, if possible, I strongly recommend assembling a similar structure for yourself, at least for the sake of interest. Again, the budget for this outrage is not very large; as a rule, domestic speakers in good condition are used, 5gdsh, 8gdsh, 4gd-8e, etc.

Acoustic design - the same shield or closed box, preferably of a tricky shape, for example triangular. One of the problems to be faced is the high total resistance; not every amplifier will reveal the potential of the “array”. Serial samples produced at the factory have more complex solutions; speakers are often assembled into clever modules, and filters are added.

Bass reflex, bass reflex port, Helmholtz resonator, aka a box with a “pipe”

Here it is - the most popular acoustic design option. The most favorable price/result ratio becomes widespread; our case is no exception to this rule. For those who haven’t downloaded the archive of an unknown audiophile, we’ll explain it in layman’s terms. There is a certain volume of air in the bass reflex pipe, which depends on its length; it is also “connected” with the air contained inside the speaker. With successful adjustment of the pipe length (let's not dive into theory right away), it is possible to achieve more confident reproduction of low frequencies than just in a closed box. To put it even simpler, with a bass reflex you get deep bass. For a more in-depth understanding, here is a video from a channel we already love:

Although this type of acoustics is popular, it is far from easy to manufacture; one thing leads to another. Speakers that are suitable for this design are called “compression”, most often have a rubber surround and a frequency band that requires the installation of a high-frequency link, tweeter or tweeter, that is, an electric filter is added. The choice of the optimal housing volume, its geometry, and precise adjustment of the pipe length are of great importance and do not always correspond to the calculated values. The situation is made easier by the presence of a mass of projects on the Internet, where the authors have already gone through the thorny path and offer step-by-step instructions with a detailed description of what, how, and what to do. However, there are always enthusiasts who are not satisfied with what is “ready-made” and have the tenacity to go their own way. The disadvantages of the bass reflex are “mumbling” and “crushed middle”. The first is solved by careful selection of the shape, diameter, material and length of the pipe; the second is by adding a separate mid-frequency section. The right path to three-way acoustics.

TQWP Reverse Horn and Other Labyrinths of Fate

What people haven’t come up with to complicate the path of vibrations coming from the back of the speaker... Perhaps the company that distinguished itself most of all was B&W with its Nautilus, at least erect a monument to this mutant sea shell. But these are grandees, and all we, ordinary audiophiles, can do is remember our nightmares and place boards with nails inside the rectangular box so that this vile sound doesn’t seem enough. Seriously though, there are speakers for which the “bass reflex” type design does not suit, and the shield does not provide the desired amount of bass, and the sight of the subwoofer makes something clench in your stomach. Then a reverse horn or a more complex option - a labyrinth - comes to the rescue. For those who are interested in how it works, we wish you pleasant viewing.

Someone may object: a reverse horn is not exactly a labyrinth, we can partly agree, but what is more reliable is that it is closer to labyrinths than a classic horn

reminiscent of an old gramophone. As you can guess from the name, a reverse horn or labyrinth is far from the simplest type of acoustic design; it requires a good understanding of the theory, accurate calculations, or at least compliance with factory recommendations. For example, large manufacturers of wideband speakers, as a rule, provide a couple of variants of housing drawings in the documentation for their speakers.

Onken, closed box (CB), horn, passive radiator and others

Our narrative follows in the footsteps of popular popularity, and this is a rather narrow list. A closed box almost always mumbles, it’s difficult to find a speaker for the onken, the horn is large in size, difficult to manufacture and calculate, the passive radiator works well, but for some reason it has not taken root in amateur designs. You can probably find several more rare types or subtypes of design that are not mentioned here, but what can you do, you can’t cover everything.

Damping, "stuffing", "plug"

The cases are ready, what to do with them next? That's right, damping. Damping can be divided into two types: vibration absorption and sound absorption. Automotive materials, mastics and special sheets with an adhesive layer are well suited for vibration absorption, the latter being preferable. With sound absorption there is confusion and swaying, some people like felt, others like wool, batting, padding polyester, etc. The answer is quite simple - for different effects, depending on the type of housing and the frequency that you want to suppress, the choice of material will depend. Filling the case with sound-absorbing material increases its virtual volume, however, in my opinion, it is impossible to determine a universal norm.

Setting up a crossover (crossover filter)

You decided to make multi-band acoustics. Is a measuring microphone necessary? If this is a one-time project, then no, it is not necessary, it is enough to have a test selection of tracks and some experience to understand which sound can be called more correct. You’ll just have to go through the details of the passive filter longer, listen and compare, but in the end the result will be exactly what your ears and the room need. The situation is a little easier with active crossovers. Previously, you had to make them yourself, etching and routing boards, soldering, a very tedious process, especially if the circuit has a decent slope of cut and adjustment, for three-way acoustics it’s just a wild thing. Fortunately, today you just need to go to ebay and choose an option that suits your budget, whether you want it on op-amps or on DSP. You can smoothly adjust the frequency, and sometimes the slope of the cutoff (in especially rare cases, the phase), even every day.

The final

Sometimes it seems to me that the situation in the audio world is reminiscent of the legend of the Tower of Babel. Once upon a time, in distant times, when Van Den Hul's foot had not yet set foot on the ground, people built together one set of home stereos. Large, large speakers, an equally large amplifier, and thick, thick cables stretched to them. Someone from above saw this and was horrified - what a joke, if only they had read some books... Severe punishment befell the unlucky audiophiles, since then they have been arguing until they are hoarse, but they still cannot agree on how to make amplifier speakers, so everyone makes their own , how can.