Acoustic system with your own hands. Homemade speaker system Drawings of the best homemade home speaker systems

Today I will tell you, dear Durkovites, how to make with your own hands something that costs a lot of money in a store. That is, a good speaker system. I remember how I posted here about the S-30, and from that moment I started making my own speaker system from scratch.

To begin with, when I found this pair of S-30s in a shed at the dacha, I was almost stunned - not only were they different (one s-30B and the other S-30A), but another one had a broken body. The second one was not inside the filter, someone had already removed it before me. There was no point in doing restyling - they are too different, and I didn’t know how to restore the half-rotten body. And why, when you can re-make 2 identical ones. The woofers, GDN-25, are in perfect condition, but it is better to install new tweeters. Well, let's start.
Part one. Columns.

I didn’t think about the material for a long time - there were walls from some sort of soviet sideboard (chipboard 16 mm), and with holes. We hammer holes with dowels on pva. Next, cut to size. Oh yes, the most important thing is the size. I took approximately the same dimensions as the original S-30, only slightly changed the shape. But the phase inverter had to be calculated in SpeakerShop "e. I took it with a margin of 50 mm. We twist the case with self-tapping screws, this is still a fitting.

We disassemble, smear with glue, collect. We glue the glazing beads into the corners for greater strength:

Now we dampen everything with linoleum, the shaggy side inward:

We collect completely.

Now that everything is working for us and it doesn’t whistle anywhere, we can putty.

Well, now the most dreary and dusty sanding ...

After a couple of hours, something even and velvety is obtained. Can be glued. At first I wanted a black self-adhesive under a tree, but in our, sorry, Muhosransk, it didn’t turn out. But how nice it is to have friends in other cities! A month later, of course, I will have it, but for now I will have to paste over it with what I have. roughly like this:

In order not to mess with the style of the front panel, we make a black acoustic grill. (It’s better to make it from acoustic fabric, but if the budget is tight, you can get by with women’s black tights, you can’t distinguish them by appearance. The most important thing is to ask your girlfriend / girlfriend / mother for permission to take these very tights. Sometimes they cost many times more than the acoustic fabric itself so be careful ;)

It turns out no worse than bought, it seems to me:

While I was making the amp (more on that later), they brought me a self-adhesive. My joy knew no bounds!

And now the most important thing - do not save on connectors! I first bought Chinese for 15 rubles, and was very disappointed. They make very unpleasant sounds at low frequencies, don’t do anything with them. Therefore, I bought some branded ones, with gold-plated contacts. Believe me, this greatly affects the sound. The extra $300 is worth it.

Now we put the tweeter. I bought automobiles, I didn’t find normal ones with us, dug out the speakers themselves from the case, put them in a hollowed-out recess on a pva-based putty.

Well, and most importantly, because. the domes on the woofers had to be removed because of their rattle, I made new ones, with their initials :)

Needless to say, the sound turned out no worse than the branded speakers of the famous audiophile trends.

Part two. Amplifier.
The speakers turned out like the original, 30 watts each - 25 watts of LF and 5 watts of HF, (although according to the documents it is written that these tweeters are 60 watts each, it’s more expensive for the Chinese to believe in themselves. The sound is no more than 5 watts) At first I had an amplifier-collected a year ago from the AT power supply and mikruhi TDA1558Q. But firstly, there are only 44 watts, and secondly, this mikruha draws basses rather weakly. I did not think about the choice of the Microcircuit for a long time - TDA 8560Q. Similar to the previous one, only the output is up to 80 watts, + the signal quality is higher and there is less distortion. I immediately warn beginners - it’s better not to collect anything on 8560, it’s very capricious. But if the hands grow from where they need to, then you get a wonderful amplifier. While I was collecting my own, I burned two pieces. And they cost about 150 rubles a piece, which money I feel sorry for, so I honed my stock of obscene language well. The body will be made of one-sided foil fiberglass. Convenient, lightweight, and does not conduct current where it is not needed. And it is also a wonderful mass, screen and antenna (if you connect a phone with a radio)

We mark, cut with a jigsaw, drill the necessary holes:

I could not resist and tried on future connectors :)

We skin the places of soldering, we play.

We heat the tinned places with a soldering iron - and everything seizes wonderfully:

Now we putty all the cracks and joints with auto-putty. After a day, we boldly skin and polish.

Let's try the stuffing:

Everything works, you can paint. We paint with glossy black paint, after which we skin the defects.

And now the main highlight is aluminum inserts. A parody of expensive amplifiers, similar to protective steel corners. We cut out a 3mm aluminum sheet, bend it to the shape of the front panel, give it a texture with sandpaper, and screw it with hex bolts (namely, bolts, this is also part of the design). Looks cute:

We remove all props and take out the filling. We paint normally:

It turned out here is such a small wonderful case:

Now about the stuffing. Mikruha Tda8560 on a radiator from the 300th Celeron, a transformer (which is 40 years old, no less, but gives out about 15A and 12V), a diode bridge of about 12A and 3 capacitors: 4700uF, 2200uF and 0.47uF connected in parallel. Two conders at the signal inputs of the mikruha, 0.05 microfarad each (also Soviet, much better than the Chinese ones), and an input dual variable resistor of 50 kOhm. .

And so that the 2-kilogram transformer does not warp the case, we strengthen it with two corners and a steel plate at the base, on which everything is actually attached.

Now we make the bottom from the same textolite and legs from a nickel-plated furniture tube:

It looks good next to my system unit, the same blue backlight (unfortunately, the computer is turned off in the photo):

Part three. The final.

Here everything is assembled and works great. In total, it took me about three months. And I’ll say right away that there are only a third of the photos here, the rest show what went wrong with me, after all, this is my first project with such accuracy and such a high-quality study of every little thing.

P.S. I'm in the 10th grade, and this is supposedly my project for a regional technology olympiad, where, by the way, I took first place 3 days ago.

Happy modding! Sincerely yours, Viktor Sarbaev.

Recently, an article about a home-made tube amplifier was published in the World of Homemade Products, today it's the turn to tell you how to make acoustics for a tube amplifier with your own hands.

Want great acoustics? Not prestigious, from well-known companies, namely, a classy one that gives out a detailed, deep, atmospheric and quite energetic sound? If you don't live in a castle and don't plan on sounding the stadium or trying to impress your neighbors three floors down, but want to enjoy the music, maybe my acoustic recipe is for you.

There are things that you really want to do, but the lack of funds, materials, equipment, etc. stops you. But I really want to ... I gave myself a pendel, and it took off ... According to the principle: “I want it, because I like it!” and because we must finally make acoustics for my . I wanted to assemble a speaker that sounds good in both a large and a small room, and at the same time elegant, not cabinet-like. Still - an element of the interior. In any case, it should be a floor speaker, since the “shelf speakers” still need to be placed on racks.

creation

For the tube single-cycle speakers, I also chose "tube" ones: 4GD-35 (4GD-36) and 3GDV-1 (2GD-36), widely known from Soviet radios.

3GDV-1(passport data):

Frequency range: 3150-20000 Hz;
Frequency response flatness: 14 dB;
Sensitivity: 90 dB;
Working power: 2W;
Harmonic coefficient in the frequency range 4000 - 10000 Hz: 3%;
Resistance: 8 ohm;
Nameplate power: 3 W;
Long-term power: 3W;
Short-term power: 6W;
Main resonance frequency: 1200 - 2000 Hz;
Weight: 0.11 kg.

4GD-35 (4GD-36)(passport data):

Frequency range: 63 - 12500 Hz;
Frequency response flatness: 16 dB;
Sensitivity: 92 dB;
Working power: 0.8W;
Harmonic factor at operating power: 125 Hz: 7%, 200 - 300 Hz: 5%, 1000 - 8000 Hz: 3%;
Resistance: 4 ohm;
Passport and long-term power: 8 W;
Short-term power: 15W;
Total quality factor: 1.4 (±0.3);
Main resonance frequency: 65 Hz (+20, -15);
Dimensions: Ø 200 x 75.6 mm;
Weight: 0.88 kg.

According to my comparative measurements, it turned out that 4GD-36 and 4GD-35 have the same frequency response, but 4GD-36 sounded more comfortable for hearing.

Four design options were considered:

Open box. Semi-open box.
Closed box. A box with a cat hole.
TQWP - (TaperedQuarter-WavePipe - Expanding Quarter Wave Pipe).
Quarter-wave resonator (TwinPipe) in the image of Castle Knight 5, from the British Castle Acoustics.

All options are noteworthy and have shown certain advantages and disadvantages in sound, although officially these speakers are designed for open design.

After sawing and breaking a bunch of boards, I share the results.

Open box. Classic light sound. Many may like it, but the reflections from the walls do not allow you to build a clear scene. If the body is closed at the back with a piece of felt (about 1 cm thick), then the situation is somewhat corrected. This design (called: aperiodic load) showed the best linearity, but at the same time more modest dynamic performance and sensitivity. The construction of the scene was also not impressive. Everything is very academically correct, but dry. The room is 10 sq. You can still listen to m, but in twenty meters it became boring - a weak attack.

A box with a sound port on the front. Simple and quite effective. The bottom sticks out, the rest is in the norms of decency. Sensitivity and dynamics are average. For a room of 20 meters, it may be suitable, but at 10 meters it “blows”.

Since I wanted something with a twist, I settled on the “from the knight's castle” option. In fact, the Twin Pipe showed more sensitivity and better bass control than the popular TQWP. The sound is light, aggressive and open. The bass is adequate in both small and large rooms. The scene and detail are pleasing. The linearity, however, of this "mustang" is not at all high-fidelity: 18db (relative metering in the resonant room), with a certain resonator setting, you can lower it to 14db. The only significant drawback - the sound gives a "box". The sound port on the front panel is to blame for this. You can deal with this by densely dampening the case with various materials, but the sensitivity drops and then the meaning of choosing such a design is lost.

In general, all sound ports and phase inverters serve to bring out all sorts of uterine sounds, so if you don’t want to listen to how the inside sounds, it’s better not to use them.

Ronnie Dio has a song on his album "Bad Dream" - "All the fools swam far away." This is probably about me, and now I'm proud of it.

So what am I inventing? A bicycle with square wheels… based on an open speaker… The problem is that the acoustics need a back wall for a good attack. Take I 10GDSH-1-4 and such questions would not have arisen at all. Put it in a box, or in a big box with a fuzzy, it will “sing”. But I've already gone too far. The hull for 4GD-36 is ready, and this is ZYA!

Testing and listening...???

Regardless of the style of music, the sound is aggressive and harsh, like a heavy metal concert. Drums and guitars break through walls and ears. Having enjoyed this "joy", I wanted to return to musicality.

Where to swim now? I return to the aperiodic load, but now with the addition of a padding polyester. I lay the fluffy synthetic winterizer in a wave, and close the back of the speakers with felt 5 mm thick.

Here he is! The musical sound I need is received. Light open sound that does not hurt the ear, but has sufficient dynamics. Even Le Binks' drum intro to Judas Priest's Better by you, better than me sounds convincing like a concert. Doing a “deep” audition… It’s been three months…

Conclusion

First about the bad. Acoustics and my one-beat are not "friendly" at all with modern compressed music and with musical styles of increased density and assertiveness, whether it's electronics or trash metal and the like. At the exit, creaking porridge.

About good. Classic heavy metal plays well (but not stunning). Hard rock is good. Led Zeppelin and early rock in general, before 1976, sound very organically (apparently old recording technologies let you know). Electronics: Kraftwerk, Yello, Enigma, Era, B-Tribe.

About magnificent. Antonio Vivaldi and violin classics in general. Chamber jazz, such as Diana Krol and the like. All vocal parts of all singers are perfectly reproduced by a bunch of Magnifique Evolution & Magnifique Accustic. With a claim to luxury!

Recipe and Ingredients

Body made of 16mm thick laminated chipboard. Fastening internal: slats, screws, glue. I did not thicken the walls additionally (except for the lower part of the front panel), arguing that the acoustics are low-power.

Internal damping of the case: felt, synthetic winterizer.

Under the speakers, you need to put a sealant or “plant” them on plasticine.

Base: chipboard with a decorative aluminum corner around the perimeter.

Legs adjustable, on the basis of furniture nuts "crab".

Filter - capacitor MBGShch-2 4mkf 160v.

The speaker connection is in-phase.

Internal copper wires 1.5 mm "Odeskabel".

Soviet instrument connectors for "banana" (turned bronze contact in a carbolite case).

Cable "amplifier-AC": Odeskabel 2X4mm; Profigold banana connectors.

Total: $72.

After assembling the case, fixing and connecting the speakers, place the speakers in the position you need in the room. Listen to your favorite music at the volume you want. Add felt and synthetic winterizer "to taste", achieving the shade and sound you need.

Thank you for your attention and I wish you success.

Application

Reasoning about

It is widely believed on the net that it is possible to design speakers only if you have a professional measuring microphone in your arsenal, or even better, a sound level meter (for example: VShV-003) and a thoroughly damped, muffled room, without resonances. Next, you need to thoroughly study the work of design and simulation programs. And already on their basis, from special audiophile materials, to make a really “correct speaker”.

All this is partly true. Partly... More precisely, not quite, really. That is, in real life, it will not be so at all.

Even if you have VSHV-003 or its analogue lying around in your closet, the measured frequency response, in a city apartment, will be replete with resonant distortions that cross out all the potential accuracy of the measuring equipment. For the same reason, you should not "hunt" for some special microphones, such as the PanasonicWM-61A.

Programs for designing speaker cabinets, of course, help you navigate, but purely virtual.

The main thing is the concept and the desire to implement it on the basis of common sense and proportionality. A live experiment will always show what is better and what sounds worse in a particular environment, for which the speaker is being created. For example: the speaker needs air - this is a fact, so you shouldn't squeeze it into a cramped closed box, but you shouldn't put it in a huge wardrobe either. Its installation dimensions already indicate the minimum proportions of the speaker cabinet in width, and in depth and height, statistically, this is twice as much. The height of the speaker from the floor affects the transparency and density of the bottoms and is determined only empirically in a specific situation, and not by sophisticated programs that are closed on themselves.

Even more creativity involves the process of damping the body with different materials (felt, linoleum, cotton wool, synthetic winterizer, etc.). Having done everything right, on the recommendation of dealing with resonances, you can completely kill the music in the sound.

The damping factor and impulse response of your amplifier will force your designed speakers to work only as they please, violating all the rules and canons. The conclusion is to experiment, listen and correlate with relative measurements. These measurements can be easily done with a simple measuring microphone assembled from a cheap Chinese microphone and any linear amplifier on the same chip. Then connect it, at least to a sound card, or in the old fashioned way, “buzz” with a generator and a millivoltmeter.

I made my measuring microphone based on a Chinese with a meaningless name JM901, and a linear amplifier based on K157UD2. I collected it about 15 years ago, just for the sake of interest and put it in the pantry. Now, all of a sudden, he came in handy and did his job perfectly.

Speaker system device

There is no chance of making a speaker system yourself without understanding the theory. Music lovers should be aware that the biological species Homo Sapiens hears sound vibrations of frequencies from 16-20000 Hz with the inner ear. When it comes to classic masterpieces, the spread is high. The bottom edge is 40 Hz, the top edge is 20,000 Hz (20 kHz). The physical meaning of this fact is that not all speakers are able to reproduce the full spectrum at once. Relatively slow frequencies work better with massive subwoofers, and beeping at the lower border is reproduced by smaller loudspeakers. It is clear that for most people this means nothing. And even if part of the signal is lost, will not be reproduced, no one will notice it.

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

In connection with the above, we will divide the acoustic systems:

The sound in Mono format is unpopular, so we avoid touching on historical digressions.
Stereo sound is provided by two channels. Both contain low and high frequencies. Equal columns equipped with a pair of speakers (bass and squeak) are better suited.
Surround Sound is distinguished by the presence of a larger number of channels, creating a surround sound effect. We avoid getting carried away with subtleties, traditionally 5 speakers plus a subwoofer convey the gamut to music lovers. The structure is varied. Research is still ongoing to improve the quality of acoustic transmission. The traditional arrangement is as follows: at the four corners of the room (roughly speaking) along the column, the subwoofer is on the floor to the left or in the center, the front speaker is placed under the TV. The latter in any case is supplied with two speakers or more.

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

The scope of tasks is outlined, readers understand that a home-made acoustic system is built with the following elements:

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

Acoustic design

Initially, we select the number of columns, type, location. Obviously, to produce in a larger number than the home theater has channels is an unreasonable tactical move. A cassette recorder needs two speakers. At least six cases will be released for the home theater (there will be more speakers). According to the needs, accessories are built into furniture, the quality of bass reproduction is lame. Now the question of choosing speakers: in the publication of the authorship of Naidenko, Karpov, the nomenclature is given:

Bass - CA21RE (H397) 8" fit.
Medium range - 5" MP14RCY/P (H522) head.
Treble - head 27TDC (H1149) 27 mm.

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

The next question is the filter. We believe that National Semiconductor will not be offended if we scan the drawing of the Ridiko translation amplifier. The figure shows an active filter powered by +15, -15 volts, 5 of the same type of microcircuits (op-amps), the cutoff frequency of the subranges is calculated by the formula shown in the image (duplicated by text):

P - Pi known to schoolchildren (3.14); R, C - ratings of the resistor, capacitance. In the figure, R \u003d 24 kOhm, C - is hushed up.

Active filter powered by electric current

Given the capabilities of the selected speakers, the reader will be able to choose a parameter. The characteristics of the column playback band are taken, the overlap junction between them is found, and the cutoff frequency is placed there. Thanks to the formula, we calculate the value of the capacitance. Avoid touching the resistance value, reason: it can (disputed fact) set the operating point of the amplifier, the transfer coefficient. On the frequency response given in the translation, which we omit, the boundary is 1 kHz. Let's calculate the capacity of the specified case:

C \u003d 1 / 2P Rf \u003d 1/2 x 3.14 x 24000 x 1000 \u003d 6.6 pF.

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

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

Passive filters will assemble with their own hands each trained in soldering, a school physics course. In an extreme case, enlist the help of Gonorovsky, there is nowhere better to describe the intricacies of the passage of signals through radio-electronic lines with nonlinear properties. The presented material interested the authors in low and high frequency filters. Those who want to divide the signal into three parts should read the works that reveal the basis of bandpass filters. The maximum allowable (or breakdown) voltage will be scanty, the value will become significant. To match the mentioned electrolytic capacitors with a nominal value of tens of microfarads (three orders of magnitude higher than those used by an active filter).

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

For passive speaker crossovers, you will find many calculators on the Internet (http://ccs.exl.info/calc_cr.html). The initial figures of the calculation program takes the input impedance of the speakers, the division frequency. Enter the data, the robot will quickly supply the capacitance and inductance values. On the given page, set the filter type (Bessel, Butterworth, Linkwitz-Riley). In our opinion, a task for the pros. The active stage shown above is formed by 2nd order Butterworth filters (frequency response reduction rate of 12 dB per octave). It concerns the frequency response (frequency response) of the system, it is clear only to professionals. When in doubt, choose the golden mean. In the literal sense, check the box on the third circle (Bessel).

Acoustics of computer speakers

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

The most expensive component of the music center. Hi-end class acoustics bypasses a cheap apartment in cost. Repair, assembly of speakers is a good business.

The low-frequency amplifier of the speaker system will assemble an advanced radio amateur, no Kulibins are needed. A volume knob sticks out of a matchbox, input on one side, output on the other. The speakers of the old speaker system are small. The young man got hold of an old loudspeaker not of fabulous size, but solid. From a Soviet-era speaker system.

So that the sound would not disturb the air with a squeak, the clever boy knocked together inch boards in a box. The speaker of an old acoustic system was placed in the size of a mailbox, shifted, as is done by manufacturers of modern home theater subwoofers. I was too lazy to finish the speaker from the inside with a sound insulator. Those who wish can use batting or other similar material for the speaker system. Small speakers are placed inside oblong boxes, just containing the end of the loudspeaker. The proud lad connected one channel of the speaker system to two small speakers, the second to one large one. Works.

The young man is a fabulous fellow, does not drink in the alley, becoming like his peers, does not spoil future brides in his free time, is busy with business. As one friend said: “The young generation is forgiven for the lack of knowledge and experience, not the excess of arrogance, reinforced by indifference.”

Improvements

We decided to improve the technique, frankly we hope that the addition will help to make the speaker system a little better on its own. Problem? The concept was invented by radio engineers, the creators of acoustic systems - frequency. The vibration of the universe has a frequency. They say that even the human aura is inherent. It is not for nothing that each good speaker can accommodate several speakers. Large ones are for low frequencies, bass; others - for medium and high. Not only the size, but also the device they have is different. We have already discussed this issue and we refer those who are interested to the written reviews, where the classification of acoustic systems is given, the principles of operation of the most popular ones are revealed.

Computer scientists know the BIOS interrupt system buzzer, which seems to be capable of producing a single sound, but talented programmers have written fanciful melodies on it, even with an attempt at digital synthesis and voice reproduction. However, if desired, such a tweeter cannot produce bass.

Why this conversation ... A large speaker should not just be adapted to one of the channels, but bass specialization should be awarded. As you know, most modern compositions (we don’t take Sound Around) are designed for two channels (stereo playback). It turns out that two identical speakers (small ones) play the same notes, there is little point in this. At the same time, bass is lost from the same channel, and high frequencies die on a large speaker. How to be? We propose to introduce passive band-pass filters into the circuit, which will help to split the stream into two parts. We take the scheme of a foreign edition for the simple reason that it was the first to catch our eye. Here is a link to the original site chegdomyn.narod.ru. The radio amateur re-shot from the book, we apologize to the author for not indicating the source. This happens for the simple reason that it is not known to us.

So, picture. The words Woofer and Tweeter are immediately evident. As you might guess, this is, respectively, a subwoofer for low frequencies, and a speaker for high frequencies. The range of musical works is covered from 50-20000 Hz, and the subwoofer accounts for the low-frequency band. Radio amateurs themselves can calculate the bandwidth using well-known formulas, for comparison, for the first octave, as you know, is 440 Hz. We believe that such a division is suitable for our case. I would just like to find two large speakers, one for each channel. Let's see the diagram...

Not quite a musical scheme. In the position occupied by the system, the voice is being filtered. Range 300-3000 Hz. The switch is signed Narrow, translated as a stripe. To get Wide (wide) playback, omit the terminals. Music fans can throw away the Narrow bandpass filter, Skype surfers are advised to avoid a hasty decision. The circuit will completely exclude the microphone loop effect, known everywhere: a shrill buzz due to overamplification (positive feedback). A valuable effect, even the military knows the difficulties of using a speakerphone. The owner of the laptop is aware...

To eliminate the feedback effect, study the question, find at what frequency the system resonates, cut off the excess with a filter. Very comfortably. Regarding popular music, we turn off the microphone, take it away from the speakers (the case of karaoke), and start singing. We will leave the high and low pass filters unchanged, the products were calculated by unknown Western friends. For those who have difficulty reading foreign drawings, we explain, the diagram depicts (the Narrow band-pass filter is discarded):

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

Speakers must match. Suggestions for this site. The subwoofer will be MSM 1853, the tweeter (the word was not written off) will be PE 270-175. You can calculate the bandwidth yourself. The capital letter Ω means ohms - there's nothing to worry about, change the denomination. Remember, the capacitances of capacitors connected in parallel add up like series-connected resistors. In case it is difficult to get suitable denominations. It is unlikely that it will be possible to make speakers with your own hands, it is realistic to dial small resistance values. Do not use coils, we cut out plates of nichrome, similar alloys. After manufacturing, the resistor is varnished, no high current is planned, the element should not be protected.

It is easier to wind inductors yourself. It is logical to use an online calculator, by setting the capacitance, we will get the parameters: number of turns, diameter, core material, core thickness. Let's give an example, avoiding being unfounded. We visit Yandex, we type something like "online inductance calculator". We get a number of issuance responses. We choose the site you like, we start thinking about how to wind the inductance of the speaker system with a nominal value of 0.27 mH. We liked the site coil32.narod.ru, let's get started.

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

The question immediately arises, seeing the calculator, where to get the nominal diameter of the insulated wire ... We worked hard, found on the site servomotors.ru a table taken from the reference book, which is given in the review, consider it to your health. The diameter of copper is 0.2 mm, the insulated core is 0.225 mm. We boldly feed the values \u200b\u200bof the calculator, calculating the required values.

It turned out a two-layer coil, the number of turns is 226. The length of the wire was 10.88 meters with a resistance of about 6 ohms. The main parameters are found, we begin to wind. A home-made speaker system is made in a hand-made case, there is a place to fit the filter. We connect a tweeter to one output, a subwoofer to the other. A few words about amplification. It may be that the amplifier stage will not pull four speakers. Each scheme is characterized by a certain load capacity, you cannot jump higher. The loudspeaker design is designed with a fixed headroom to match the load, often using an emitter follower. The cascade that makes the circuit work, full return on any speaker.

Parting words to novice designers

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

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

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

Acoustic design does not mean decorating the speakers with antique-style carvings, although this will give the speakers a uniqueness, but a solution to the problems of acoustic short circuits.
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 oscillates around the basket of the dynamic head 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.
The ways 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 the use of sheet material in the middle of which a hole is cut out for the dynamic head. This is called an acoustic screen:

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

Both of the above methods have too little efficiency, therefore, they are practically not used only in cases where "there is no fish and cancer - fish."
It is much more efficient 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 a sufficiently large pressure arises in the box (when the diffuser goes inside the box), and a sufficiently large rarefaction (when the diffuser moves out) :

The next option for acoustic design is a box with a phase inverter:

In this case, this is a rectangular hole located in a strictly calculated place 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 phase inverter is calculated, the main purpose of which is to invert, i.e. reverse phase. As a result, sound is emitted into space not only by the front of the diffuser, but also by the back, the phase of which is changed by the phase inverter.
A more complex version of acoustic design is an acoustic labyrinth. The essence of this option is that the strokes inside the speakers are located in such a way that resonance occurs at a certain frequency and, as a result, a large increase in returns at this frequency. The calculation and accuracy of manufacturing such systems should be taken VERY seriously, since there is a high probability of the occurrence of "standing" waves in the labyrinth. In this case, the sound quality will be even worse than with an acoustic screen:

An even greater return at the resonant frequency allows you to get a horn version:

The difference between a horn speaker and a labyrinth speaker is that the direction of the sound waves in them changes according to different laws - the horn one 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, and 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 the previous ones primarily in that it radiates only at the resonance frequency and requires the strictest observance of the calculated dimensions.
The last three options are mainly designed for the use of a low-frequency dynamic head, and the previous ones are quite suitable for broadband speakers. Therefore, if the speaker system has others besides woofers, such as midrange and tweeters, then it is not recommended to embed them into the case with a woofer.
In any case, to calculate the size of the speakers, the characteristics of the dynamic head, in particular the Thiel-Small parameters, will be required. If these data are not available, but before taking on the calculation of the dimensions of the speaker cabinet, they must be obtained. There are quite a few descriptions of methods for obtaining these parameters - just use any search engine.
Of course, this is 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, some technological features should be taken into account - if the front panel on which the speaker is installed is recessed into the case, then additional ribs will need to be made, into which the front panel will actually rest:

If you don’t want to mess with the ribs, then you can make the front panel so that it rests on 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 case.
Also, you should not forget about the ways of fastening 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, however, this method involves chamfering the diameter of the dynamic head and sinking the speaker into the case so that ALL emitters, and bass, and midrange, and treble are on the same line. chamfering reduces the mechanical strength of the front panel and its restoration will require an additional ring fixed from the inside. The relevance of this ring is the higher, the more power is expected to be obtained from the manufactured speaker, and at powers above 150 W it is already 100% necessary:

On the ring, if necessary, it will be necessary to remove the side chamfers so that it does not interfere with the front panel of the installation in the case itself.
When installing the dynamic head, it is necessary to ensure that there are no gaps. If the chamfer is removed by the machine, then the surface is relatively even, it remains only to sand it. However, at home, getting a flat surface is quite difficult. Here, the action of the manufacturers is not entirely clear - it is highly 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 a door seal - self-adhesive strips of porous rubber, sold in all hardware stores. The sealant is glued around the perimeter of the chamfer and, when mounting the speaker, completely fills all the cracks:

If the driver is installed from the inside, the hole will need to be chamfered to prevent standing waves. However, such a chamfer weakens the rigidity at the point of attachment of the speaker to the panel (the material turns out to be too thin) and this method of attachment is not acceptable for powers above 50 W without additional structural reinforcement:

It is desirable to use natural material for the manufacture of speaker cabinets, plywood is optimal, but this material is painfully expensive. Therefore it is better to use plywood for building medium to high priced speakers using VERY good quality drivers above 100W.
For the middle price category and low power (up to 50W), you can use fiberboard or MDF (the same as fiberboard, only the thickness and density are greater), but it needs to be processed and finalized, or chipboard.

For powers up to 10 W, plastic is also quite suitable, but also using technological tricks.
The first problem, in the manufacture of speakers from plastic, arises when the rattle of the plastic itself is eliminated, especially manifested in the centers of the sidewalls. You can get rid of this unpleasant sub-sounding using thicker plastic, or you can glue additional stiffeners. If the plastic is dissolved by dichloritan, then dichloritan with plastic chips dissolved in it can be used to fasten the ribs. If the plastic does not dissolve with dichloroethane, then it is better to use epoxy glue, preferably Dzerzhinsky production. Before gluing, carefully treat the contact points with coarse sandpaper and do not be afraid that the glue forms rollers at the point of contact of the parts to be glued:

For greater efficiency in suppressing overtones of the body, it is possible to "paint over" the resulting "baths" in 2-3 layers with anti-gravel - a coating used to cover the bottom of cars to protect against fine gravel.

After drying, the anti-gravel acquires the properties of rubber and absorbs sound quite well.
When used as a material for the manufacture of AS fiberboard, it is required to determine the required thickness. If the speaker power does not exceed 5 W, then fiberboard can be used in one layer. Before cutting fiberboard, it is coated with epoxy glue on one side and heated with a hairdryer. Under the influence of temperature, the glue becomes more liquid and impregnates fiberboard to almost half the thickness. After the glue hardens, a rather strong material is obtained, essentially a getinaks, but on the one hand, it retains the sound-absorbing properties of fiberboard. You can cut the WPV with an electric jigsaw, you can glue the workpieces with epoxy glue reinforced with material. To do this, the blanks are folded into the desired design, and grabbed with any SUPER GLUE. 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 soldering iron at 40 ... 60 W. High temperature allows the glue to completely saturate the weave, and also significantly accelerates the polymerization of the glue. True, a certain amount of smoke is emitted during operation, so work must be done either on the street or under the hood:

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

For powers up to 30 ... 35 W, it will already be necessary to fold the fiberboard three times or use 18 mm thick chipboard (unfortunately, 22 mm thick chipboard can only be found in old grandmothers in the form of old, until the 80s of production, chiffoniers). To stiffen the sidewalls, you can use struts 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 folding fiberboard from 4-5 layers. For this, a material with a thickness of 18 mm is suitable, however, you will have to use additional bars that provide a greater bundle of speaker parts among themselves:

Speakers can be assembled using self-tapping screws, but since there is no more power, you can also glue them with epoxy glue or PVA, but it’s better to buy it not in a stationery store, but in a household or building one. This PVA will be called MOMENT-JOINER, water-dispersion glue. Buy on the market recommended only in summer - after freezing, the glue seriously loses its qualities. However, to calm the conscience, it is better to tighten at least a couple of self-tapping screws into each bar.
In the manufacture of speakers, sometimes they make a gross mistake - the midrange-high-frequency link is not acoustically protected 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 to failure of the midrange link - too strong air shocks from the back side of the woofer cone lead to the expulsion of the midrange speaker coil from the magnetic gap and jamming, the coil is jammed.
Much more often, they forget to subtract the volume of the protective casing of the midrange-tweeters 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 intertors rises noticeably, which leads to undesirable overtones.
When assembling speakers with a power of up to 100 W, you can also use either chipboard or 18 mm thick plywood, although of course it is better to look for material 22 mm thick. To exclude the occurrence of resonances of the sidewalls of the speaker cabinet, additional bars are also used through which parts of the speaker are fastened. It will not be superfluous to install a "cross" and an additional washer for fastening the woofer of the dynamic head, as well as processing the speakers from the inside with sound-absorbing materials, for example, pasting with foam or foam plastic 5-10 mm thick, just do not forget that pasting will "eat" part of the internal volume and it must be corrected for when calculating the dimensions of the case.

Mounting foam gives the best results, since the thickness of the applied layer can be controlled by the speed at which the foam is released from the can. If the foam is released VERY slowly, it is 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 solidified, it greatly increases in volume. If foam is applied to the sides of the case from the front panel, increasing the foam output when approaching the rear wall, and at the front panel providing a minimum foam output rate, the internal volume of the speaker will take the form of a pyramid lying on its side. Such tricks can completely solve the problem 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 with the calculations of the dimensions of the workpieces - the internal volume decreases VERY strongly and this requires a serious increase in the speaker cabinet.

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

Here it should already be noted that the use of a large number of speakers, including for dividing the sound range, begins to introduce some troubles - it is rather difficult to achieve signal phasing in those places where the frequency response of speakers adjacent in range intersects. Therefore, one should not chase after a large number of bands for a home-made speaker - this porridge can be very spoiled with such oil.
It is better to make speakers with a power of 100 to 300 W from plywood, and you will have to look for plywood 22 mm thick. AC is also assembled using stiffening bars, which are glued. It is better to give the bars the shape of equilateral triangles, where the legs will be attached to the sidewalls, and the hypotenuse will be directed inside the body.
If you cannot find plywood of this thickness, then you can use plywood 8 mm thick glued three times - the final thickness of the material is 24 ... 25 mm. Adhesive masses are listed above.
As a technological advice, we can only recommend that you first cut the necessary blanks and only then glue them, and immediately tighten them with self-tapping screws.
When installing a "cross" inside the AC, which will not be superfluous, it is better to round off the corners of the stacking bars - already quite large volumes of air are already moving and turbulence may occur around the right corners of the couplers. It is also recommended to "round" all internal corners, using plasticine or applying several layers of thick anti-gravity.
Another type of acoustic design is the separate execution of cases for each speaker. In such speakers, passive filters are not used, and the signal is divided into ranges immediately after the amplifier volume control. Then the divided signal is fed to three separate power amplifiers, which actually work each on their own speaker:

It would be unfair not to mention the "fillers" often used in speakers - small rinks of sound-absorbing material lying inside the speaker. Such rollers make it possible to slightly increase the calculated internal volume of the hull, however, in order to properly manufacture such a "filler", it is necessary to know its acoustic properties. It is rather problematic to get the characteristics of the "filler" in a home environment, so it remains either to refuse to use the "filler", or to find out by experience the required volume and the material used (usually fluffed cotton wool, batting, sentipon).
With powers from 100 W, it also becomes relevant 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 desirable to break the mechanical connection between the bottom of the speaker and the floor on which the speaker is installed. For these purposes, they usually use either tripods, which are problematic to make at home, or they use steel spikes screwed into the bottom of the speaker:

At powers above 200 W, it is desirable to strengthen the front panel of the speakers and it is desirable to use materials of different structure, for example, if the front panel is made of plywood, then a chipboard sheet is glued on the inside, the thickness of which is 1.5-2 times less than the thickness of the panel. Such a combination of materials ensures the absorption of vibrations in a larger sound range just due to the heterogeneity of materials.
For greater stability of the speaker, its mass can be increased by smearing the bottom with polyurethane mounting foam and laying a couple of bricks into it, covering them with the same foam on top. After the foam has hardened, it is better to cut off the irregularities with a clerical cutter. The "stolen" internal volume must be taken into account when calculating the dimensions of the future nuclear power plant.
For powers over 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, while chipboard is used as the inner layer. Such a trick allows you to save a little - chipboard is much cheaper than plywood. Inside the speakers, it is desirable to glue with sound-absorbing material, for example, triple-stitched batting, double-stitched quadruple sentpon (sentipon can be double and quadruple), 5 ... 10 mm foam. The different structure of tightly glued materials of different structure eliminates the problem of resonance of the cabinet itself.
It is better to additionally tighten the corners with metal corners - this will add rigidity to the structure and protect the speaker corners from damage - the speakers are already quite heavy and during transportation various blows are possible from which it is the corners that most often suffer.

For powers closer to 1000 W, the thickness of the material should already be quite large, for example, two layers of plywood 18 mm plus a layer of 18 mm DPS, the total is already 54 mm, and the DPS is glued between the plywood layers, however, similarly, the speakers are already moving into the category "for scoring", 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 see that with increasing power, the thickness of the AS walls increases. This is due primarily 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 trouble that it is better to use internal pasting of the cases and minimize the overtones obtained from resonance. It is not difficult to check the resonant frequency of the case yourself. To do this, it is necessary to tilt the speaker at 20 ... 25 degrees and throw a rubber mallet on top of it from which you first pull out the handle. The slope of the AC is necessary so that the blow is single and the mallet bounces far to the side.
A microphone fixed to the speakers (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, rather rough, since in reality the "shock wave" comes from the inside, and during the experiment from the outside, nevertheless, based on the results of this test, one can judge at what frequency the body itself resonates and how quickly the damping occurs:

An ideal speaker does not cut and the moment of impact attenuates immediately, almost instantly, but the walls of an ideal speaker are made of concrete 1 cm thick for every W of power and such an speaker is more suitable for ridicule than for exploitation:

The finish of the speakers can be very different, there are no strict requirements here. If the case is made of plywood and the pattern is rather sympathetic, then the case can be sanded, and then covered several times with a colorless varnish:

You can buy valuable wood veneer and paste over the speakers with veneer to match the color of the furniture in the room:

In car audio salons, the so-called acoustic fabric, which is a synthetic felt, is sold. The material sticks well and stretches, which will allow you to finish the speakers at a fairly high level:

After sanding the body, you can paint it with car paint, just let's make an amendment for the fact that car enamels dry at high temperatures. Therefore, you will have to use the special IZUR hardener, the mixing proportions are written on the hardener packaging, although it is better to add it 10-15% more than the proposed proportion:

If the case is carefully sanded and sanded, then it can be pasted over with a self-adhesive film sold in OBOI stores, but this material is rather delicate and it is worth using it if there is confidence that the speakers will stand in their place for ten years:

If you plan to transport your loudspeaker frequently, 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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Having on hand a number of old and most ordinary Soviet speakers, I wanted to assemble speakers on them (MAS - small speakers) and see what can be obtained from this undertaking.
I think that the design is suitable for repetition, the cost of components is low. If I used rare imported speakers, the possibility of exact repetition would be minimal. The frequency range of the finished speaker is 40 ... 20000 Hz.

Speaker type selection

With the passage of time and the accumulation of certain experience, I gradually came to the conclusion that two-way is good, but for it it is difficult to find suitable speakers that sound good in a sufficiently wide frequency band.

There are 6GD-2 speakers and some others, but they are in short supply and small speakers cannot be made on them, 6GD-2 require boxes the size of a small refrigerator.

To get a more or less low frequency on the shield, it must be very large, this is also not a MAC. For MAS, only FI remains, because, in my opinion, there are no Soviet speakers capable of providing bass in a small SL.

All woofers known to me have a rubber suspension (they were with foam rubber, but at the moment they need a mandatory replacement of suspensions, and the volume of the box will be too big for a MAC) and sound bad at midrange, and these frequencies are very important for me because I think that they determine the overall sound quality.

All Soviet MACs are made according to a two-way scheme, they have a high crossover frequency, about 5 kHz, so they sound inexpressive due to the fact that the “rubber” woofer sounds above 1 ... 2 kHz is far from the best.

Most industrial speakers, even those assembled according to a three-way scheme, also sound muddy in the midrange. they usually have a "rubber" 15GD-11. This circumstance caused a huge number of articles on the alteration of 25AC, 35AC and their clones. Therefore, a three-way version with a paper midrange speaker was chosen for the project.
In addition, I believe that for a midrange speaker, the best design is a shield or a shallow OR. The shield is preferable in terms of sound, but inconvenient in terms of design.

Therefore, the choice of column type is as follows: three-strip, woofer in a small box with FI, midrange speaker in a small shallow OJ, tweeter on a tiny shield.

It is also necessary to refine the midrange speakers. The corrugation (the entire diffuser cannot be impregnated) is impregnated with a liquid solution of Guerlain. The process is described in detail by Shorov and his followers.
But this was not enough. When listening to the assembled and tuned speakers, the sound was somewhat harsh. The reason turned out to be the high acoustic quality factor of the speakers. I had to apply PAS, it gave a noticeable positive result.

Attempts to refine 2GD-36 according to the methodology for improving 3GD-31 did not give a positive result.

AC crossover filter

I was interested in trying the trendy sequential filters and gaining experience with them. Impressions were ambiguous.
I can say for sure that this is not a panacea. These filters require loudspeakers with flat frequency response in the operating range and without significant overshoot even outside the operating range.

I was not able to evenly reduce the midrange-tweeters at a frequency of about 5 kHz, I had to get it only at a frequency of 8 ... 9 kHz, which has its drawbacks. LF-MF section at 500 Hz.

Unlike parallel filters, where the filter for each speaker can be adjusted separately and independently, there is an undesirable interdependence here, which makes tuning more difficult.
The end result is this filter.

According to the author of this decision, the circuit has the smoothest joints, since everything that is cut off by the low-pass and high-frequency filters goes to the midrange speaker. The idea is interesting and everything would have been so if there were resistors instead of speakers. But, as I have written many times, speakers, like electromechanical devices, have their own temper and the result may not live up to expectations.

AC design

The AS consists of three buildings. The lower part is a FI with a volume of approximately 15 liters. This is more common, but I had ready-made boxes from the speakers I once bought.

I had to adapt to it. The FI pipe turned out to be very long - 27 cm, and I had to make it L-shaped. Made from a standard plumbing pipe with a diameter of about 50 mm. Since this plastic is difficult to glue, I welded it with a soldering iron, it turned out to be quite strong, the seal with the body was made with electrical tape, the seam was treated with hot glue from the inside.

The speaker front panel is removable.

The midrange speaker is in the OJ, it is desirable to make it as deep as possible. PAS is sawn from a piece of laminate, a large hole is for the magnetic system of the speaker, small ones with a diameter of 10 mm are for PAS. The number of holes is not critical, about 20 can be made.

At first I did with a margin, then sealed them with masking tape. Acoustic quality factor decreased from 11 to approximately 1. Everything was done according to Shorov's recommendations. The material is taken from an old linen sheet, stretched wet on a laminate coated with 88-Lux glue. Along the perimeter, the fabric is fixed with staples of a joiner's stapler. As the fabric dries, it stretches further.

The tweeter is mounted on a small rectangular piece of laminate.

Since three independent cases were made, it became possible to shift the speakers inward. The midrange is shifted by about 4 cm, the high frequency is also 4 cm relative to the midrange. And if the shift of the midrange speaker relative to the bass has little effect on the shape of the measuring pulse, then the shift of the tweeter is quite noticeable, the shift value is chosen optimal for listening to speakers from a distance of 2 ... 2.5 meters.

I want to note that if all the speakers are traditionally placed in one case, it will be very difficult to perform this shift. Imagine a recess of 8 cm...

One can argue about the usefulness of such a solution, but it was tried on in some columns for a very long time and I think that it was abandoned due to low technology.
However, such a solution is still used today, but not in wooden, but in cast cases - plastic or metal. To do this, the recess is made flat, some believe that this is a horn, but this is not so - this is a way to move the speakers inward.

I think music lovers will hear the difference, I did not conduct special tests on music, but tuned it with the help of computer programs and a microphone.

The height of the speaker is 73 cm, if you listen while sitting in a chair, a speaker stand is not needed. The direction of the midrange and tweeter axes is deliberately chosen.

If there are those who want to repeat my "15MAS-1", you can buy a pair of 15AC-109s in good condition (clones are not suitable) for LF boxes.
You will need to remove the tweeter and plug the hole, you can use a standard FI pipe.

Results

Thanks to the complex of the above measures, we got a good result, above expectations. The sound is not great, because. it needs higher end speakers, but a good one.

I think it's better than any Soviet small-sized speakers, which is not surprising because. they are bidirectional.
As for industrial three-strips, the situation here is ambiguous. It is clear that in terms of power (volume level), my speakers cannot compete with the 25AC and 35AC clone series.
They cannot compete in terms of the amount of bass, despite the fact that my speakers operate from about 34 Hz at a level of -3 dB, a speaker of such a small diameter is noticeably inferior in power to the woofers of the 25GD, 30GD series.

But 2GD-36 sounds softer than 10GD-35. And the main advantage is in the midrange. Rubber 15GD-11 sound clearly worse, although louder. I think the total balance is in favor of these MACs, but not for lovers of killer bass.

For home use, the volume of these speakers is quite enough, despite the low sensitivity of the 25GDN3-4. Not for disco. But you don't need quality for a disco.

The purpose of my experiments was to try out some tricks and tuning methods, to see what can be done from cheap and affordable speakers, and with a positive result, to offer Datagor readers a new article.

I think that the design is suitable for repetition, the cost of components is low. If I used rare imported speakers, the possibility of exact repetition would be minimal.
The frequency range of the speakers is at least 40 ... 20000 Hz, in fact, according to the standard method, even wider.

The speakers work well.
I do not give measurement graphs, whoever wishes - measure yourself, for example, according to the methods described by me on Datagor.

Thank you for your attention!

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