Making your own speaker systems

Before detailed consideration of the problem, we will outline the range of tasks, knowing the final goal, it will be easier to choose the right direction. Making your own speaker systems is an infrequent case. Practiced by pros, novice musicians, when shopping options are not satisfied. There is a problem of embedding in furniture or high-quality listening to the already existing media. These are typical examples that are solved by a set of generally accepted methods. Consideration we will do. We do not recommend flipping diagonally across the speaker system, get into it!

Speaker Design

There is no chance of making the speaker yourself without an understanding of the theory. Music lovers should be aware that the biological species of Homo Sapiens can hear the sound of the frequencies 16-20000 Hz in the inner ear. When it comes to classic masterpieces, the spread is high. The lower edge is 40 Hz, the upper edge is 20 000 Hz( 20 kHz).The physical meaning of this fact is that not all speakers can reproduce the full spectrum at once. Relatively slow frequencies are better managed by massive subwoofers, and squealing on the lower border reproduces less overall loudspeakers. It is clear that for most people it means nothing. And even if part of the signal disappears, it will not be reproduced, no one will notice.

We believe that those who have set as their goal the independent production of a speaker system should critically evaluate 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 an extensive band from the audible spectrum. But the subwoofer, even in complex systems one. This is due to the fact that low frequencies make the environment vibrate, penetrating even through walls. It becomes incomprehensible exactly where the bass is coming from. Consequently, the woofer column alone - a subwoofer. But as for the rest, 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 conduct the division of acoustic systems:

1. The sound in the Mono format is unpopular, so we avoid touching on historical excursions.
2. Stereo sound is provided by two channels. Both contain low and high frequencies. Equivalent speakers fitted with a pair of speakers( bass and squeak) are better suited.
3. Sound Around 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 columns plus a subwoofer convey a range of music lovers. The design is diverse. Researches are still being conducted with the aim of improving the quality of acoustic transmission. The traditional arrangement is as follows: in the four corners of the room( roughly speaking) along the column, the subwoofer stands on the floor to the left or in the center, and the front speaker is placed under the TV.The latter, in any case, is supplied with two or more speakers.

It is important to create the correct 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 radiators. You will find a video demonstrating the overall dimensions corresponding to the wavelengths of low frequencies according to science, practically remains to copy ready-made structures, and no specific literature is available.

The circle of tasks is outlined, the readers understand that the self-made speaker system is built with the following elements:

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

Designing Acoustics

Initially, select the number of speakers, type, location. Obviously, to make in more than the channels has a home theater, an unwise tactical move. The cassette tape recorder will have two speakers. At least six buildings will be released to the home theater( there will be more speakers).According to the needs of accessories are embedded in the furniture, the quality of low frequency reproduction is lame. Now the question of the choice of speakers: in the publication of the authorship of Naidenko, Karpov, the nomenclature is given:

1. Low frequencies - head CA21RE( H397) landing on 8 inches.
2. Mid Range - MP14RCY / P( H522) head by 5 inches.
3. The upper frequencies - a head 27TDC( H1149) on 27 mm.

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

The next question is the filter. We believe National Semiconductor will not be offended if we open the drawing of the Ridico translation amplifier. The figure shows an active filter with power +15, -15 volts, 5 of the same type of chips( operational amplifiers), the limiting frequency of the subranges is calculated by the formula shown in the image( duplicate text):

f = 1 / 2П RC;

P - Pi number, known to schoolchildren( 3.14);R, C - resistor ratings, capacitance. In the figure, R = 24 kΩ, C is silenced.

Considering the capabilities of the selected speakers, the reader will be able to choose a parameter. The characteristics of the loudspeaker's playback band are taken, the overlap junction between them is located, the cut-off frequency is placed there. Thanks to the formula, we calculate the capacity value. Avoid the nominal resistance touch, the reason: it can( controversial fact) set the operating point of the amplifier, the transfer coefficient. On the frequency response, given in translation, which we omit, the limit is 1 kHz. Let's calculate the capacity of this case:

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

Not so hot as a large capacity, is selected from the condition of the maximum allowable voltage. In the circuit with sources of +15 and -15 V, there is hardly a nominal value exceeding the total level( 30 volts), take breakdown voltage( reference book will help) at least 50 volts. Do not try to put electrolytic DC capacitors, the circuit gets a chance to fly up into the air. It makes no sense to search for the original LM833 chip scheme due to Sisyphean labor. Some readers will find a replacement chip, different. .. hope for understanding.

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

Passive filters will assemble with their own hands each ration-trained school physics course. In the extreme case, with the help of Gonorovsky, it’s best to have the details of signal transmission through radio-electronic lines with non-linear properties. The material cited interested authors with low and high frequency filters. Those who wish to divide the signal into three parts should be read in the works, revealing the basis of band-pass filters. The maximum allowable( or breakdown) voltage will be scanty, the nominal will be significant. In addition to the above mentioned electrolytic capacitors of capacitance of tens of microfarads( three orders of magnitude higher than those used by the active filter).

Beginners are concerned with the issue of receiving voltage of +15, -15 V power supply for acoustic systems. Wind up the transformer( an example was cited, the 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 match the ranges with the filter parameters.

For passive speaker crossovers you will find a lot of calculators on the Internet( http: //ccs.exl.info/ calc_cr.html).The initial calculation program takes the input impedance of the speakers, the frequency of division. Enter the data, the robot program will quickly provide the values ​​of capacitances and inductances. On the given page, specify the type of filter( Bessel, Butterworth, Linkwitz-Riley).In our opinion, the problem for the pros. The above active cascade is formed by Butterworth 2nd order filters( 12 dB per octave frequency response).Concerning the frequency( AFC) characteristics of the system, it is clear only to professionals. If in doubt, choose the golden middle. In the literal sense, put a daw on the third circle( Bessel).

Computer Speakers

I had a chance to look at YouTube video: the young man announced that he would do the speaker system with his own hands. The boy is talented: he has broken the columns of a personal computer — well, absolutely none — God’s amplifier with a regulator has been brought to light, placed it in a matchbox( speaker box).Computer speakers are known for poor bass reproduction. The devices themselves are small, light, and secondly, bourgeois save materials. Where in the speaker system to take the bass. The young man took. .. read on!

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

A low-frequency amplifier of the speaker system will be assembled by an advanced radio amateur; no Kulibins are needed. A volume control knob sticks out of a matchbox, input from one side, output from the other. The speakers of the old speaker system are small. The young man got an old loudspeaker not fabulous size, but solid. From the column of Soviet times speaker system.

To prevent the sound from disturbing the air by squeaking, the clever lad made inch-sized boards with a box. The speaker of an old acoustic system placed in the size of a mailbox, shifted, as is done by manufacturers of modern subwoofers home cinema. From the inside, the speaker was too lazy to decorate with a sound insulator. One can use a wadding for the speaker system, another similar material. Small speakers are placed inside the elongated boxes, just holding the end of the loudspeaker. The proud boy connected one speaker channel to two small speakers, the second to one big one. Works.

The young man is a fabulous young man, does not drink in the gateway, being like his peers, does not spoil the future brides in his spare time, is busy. As one friend said: "The young generation is forgiven for the lack of knowledge and experience, not an excess of arrogance, strengthened by indifference."

Improvements

We decided to improve the technique, frankly, the addition will help to make the speaker system independently somewhat better. Problem? The concept is invented by radio engineers, the makers of acoustic systems - frequency. The vibration of the universe has a frequency. They say that even the aura of man is inherent. Each good-quality speaker not without reason accommodates several speakers. Large designed for low frequencies, bass;other - for medium and high. Not only the size, but also their device is different. We have already discussed this issue and refer those interested in written reviews, where the classification of acoustic systems is given, and the principles of the most popular are described.

The geek is aware of a BIOS interrupt system buzzer, which seems to be capable of producing one sound, but talented programmers wrote fancy melodies on it, even with an attempt at digital synthesis and voice playback. However, if desired, the bass can not produce such a squeaker.

What this conversation is for. .. A big speaker should not just be adapted to one of the channels, but be awarded a bass specialization. As you know, most modern compositions( Sound Around We Do Not Take) are designed for two channels( stereo playback).It turns out that two identical dynamics( small) play the same notes, the meaning is small. At the same time, the bass is lost from the same channel, and the high frequencies die on a large speaker. How to be? We propose to introduce into the scheme passive bandpass filters, which will help to divide the flow into two parts. Scheme take a foreign edition for the simple reason that she first caught my eye. Here is a link to the original site chegdomyn.narod.ru. The radio amateur was recaptured from the book, we apologize to the author that we do not indicate the original source. This happens for the simple reason that he is not known to us.

So, the picture. The words Woofer and Tweeter are immediately apparent. As it is not difficult to guess, this, respectively, is a subwoofer for low frequencies, and a speaker for high frequencies. The range of musical works is 50-20000 Hz, and the subwoofer has a low frequency band. Radio amateurs themselves can calculate the bandwidth using known formulas, for comparison, for the first octave, as is known, is 440 Hz. We believe that in our case such a division will do. But I would like to find two large speakers, one for each channel. See the scheme. ..

Not quite a musical scheme. In the position occupied by the system, the voice is filtered. The range is 300-3000 Hz. The switch is signed Narrow, translated as a strip. To get wide( wide) playback, lower the terminals. Fans of music can throw out the Narrow bandpass filter, for fans of browsing Skype, we recommend to avoid a hasty decision. The scheme will completely eliminate the loopback effect of the microphone, known everywhere: a shrill buzz due to over-amplification( positive feedback).A valuable effect, even a military man knows the difficulty of using a speakerphone. The laptop owner is aware. ..

To eliminate the feedback effect, study the question, find out what frequency the system resonates at, cut off the excess with a filter. Very comfortably. Regarding popular music, we turn off the microphone, carry it away from the speakers( a karaoke event), start singing. Filters of the upper and lower frequencies will remain unchanged, the products are calculated by unknown Western friends. Difficult, reading foreign drawings, we explain the diagram depicts( Narrow band-pass filter is rejected):

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

Speakers must match. Tips from this site. The MSM 1853 will go as a subwoofer, the PE 270-175 will serve as a beeper( the word is not written off).Bandwidth count independently. The big letter Ω means kOma - there is nothing wrong, change the value. We remind you that capacitors of parallel-connected capacitors are added up like series-connected resistors. In case it is difficult to get the appropriate denominations. It is unlikely that it will be possible to make the speakers with your own hands, to dial small resistance values ​​really. Do not use coils, cut out plates of nichrome, like alloys. After manufacturing, the resistor is varnished, no large current is planned, the element should not be protected.

inductance is easier to wind independently. It is logical to use an online calculator, setting the capacity, we obtain the parameters: the number of turns, diameter, core material, core thickness. Let us give an example, avoiding being unfounded. We visit Yandex, we type something like “online inductance calculator”.We get a series of answers to the issue. Choose the site you like, we start to think 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 start work.

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

Immediately a question arises, seeing a calculator, where to get the nominal diameter of the insulated wire. .. We took the trouble, found a table on the site servomotors.ru, taken from the reference book, which we present in the review, consider health. The copper diameter is 0.2 mm, the insulated core is 0.225 mm. We boldly feed the values ​​to the calculator, calculating the required values.

A two-layer coil turned out, the number of turns 226. The length of the wire was 10.88 meters with a resistance of about 6 Ohms. The main parameters are found, we start to wind. The self-made speaker system is made in a hand-made case, there is a place for the filter. We connect a squeaker to one output, a subwoofer to another. A few words about gain. It may be that the amplifier cascade does not pull four speakers. Each scheme is characterized by a certain load capacity, it is impossible to jump above. The speaker system is designed, taking into account a fixed margin, in order to accommodate the load, an emitter follower is often used. Cascade, forcing the scheme to work, full impact on any speaker.

Parting words for beginner designers

We believe that they helped readers understand how to design a sound system correctly. Passive elements( capacitors, resistors, inductors) can get, make each. It remains to assemble the speaker case yourself. And behind this, we believe, it will not be. It is important to understand that the music is formed by a range of frequencies cut off by improper manufacture of the device. If you are going to make a speaker system, think about it, look for components. It is important to convey the magnificence of the melody, there will be a firm confidence: the work was not in vain. The speaker system will last a long time, the joy will give.

We believe that making acoustic systems with our own hands will be a pleasure for readers. The coming time is unique. Believe me, at the beginning of the 20th century it was impossible to scoop information in tons daily. The training poured heavy hard work. I had to search the dusty shelves of libraries. Rejoice in the internet. Stradivarius infused wood violins with a unique composition. Modern violinists continue to choose Italian copies. Think about it, 30 years have passed, the cart is left behind.

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