Today it is very difficult to find the right amplifier in retail trade that satisfies all your requirements, and its cost will be decent. It will be much cheaper to make a headphone amplifier with your own hands, and we will try to tell you in detail about all the necessary stages of work.

You can find many different proposals on the Internet, but we settled on the simplest and most effective amplifier circuit based on TDA 2003.

Assembled portable headphone amplifier works in classA, and its gain is about 18 units - this power will satisfy the most fastidious music lover. On some forums on the Internet, advanced radio amateurs speak very positively about this chip and the presented circuit, therefore, after assembly, you will have a very high-quality headphone amplifier in your asset. The sound row, according to the assurance of those who have already made a similar product for themselves personally, is worthy of praise: even low timbres transmitted in full without distortion - there is no need to separately assemble the ULF (low frequency amplifier).

On transistors

Such a scheme looks simple, but in operation, according to experts, it is very finicky - it all depends on the main parameters of the resistors and capacitors you choose. Its dimensions are also cumbersome - as a rule, all radio amateurs use a simple two-stage design on two transistors. Frequently used ones are KT 315 or the like, you can do anything from such devices, including a sound amplifier for headphones.

Flaws:

• a selection of the exact supply voltage for the collector, base and emitter is required:
• two types of voltages must be suitable for the base: negative and positive on separate lines with the installation of resistance;
• to ensure the rated voltage, you need to specially select resistors.

This design is picky about power supply - at least 5 V is needed for its stable operation.

Two-stage design on two transistors

We use microcircuits

When using similar products, you can get the following characteristics: the supply voltage will be in the range of 1.8-15 volts, while the output power will be up to 1.5 watts. The whole structure fits freely on a relatively small board with dimensions of 100x150 mm.

After completing all the work on assembling the headphone amplifier, if desired, some users connect small speakers from a stationary computer.

Before making a headphone amplifier, you need to go around several stores that sell radio components and purchase:

• main microcircuit - tda 2822;
• resistor variable type: with a constant nominal value of 4.7 kΩ - 2 units. and one for 10 rooms;
• capacitors 10 μF - 2 pcs.;
• non-polar film-type capacitors with a capacity of 100nf - 3 pcs .;
• two jacks for connection - 3.5 mm diameter;
• batteries;
• foil-clad material of a certain size;
• body suitable in size.

We mark the future position of the parts on the board, having previously printed a drawing on a printer using a special technology, which we will talk about below.

Position of parts on the board

We make a board

The printed product is essential if you want to make a high quality amplifier. Only if it is available will your product work stably. You can make it at home without problems if you know the subtleties LUT technology- this is the transfer of a picture of a standard board using a laser printer and an ordinary iron.

To implement our plan, we will use Sprint-Layout 6.0- Russian version, it has about 4.6 thousand macros in its assets. Its distinctive features:

• all reference data in Russian;
• the inscriptions on the board can be made in Cyrillic;
• ideal for windows 7 operating system;
• the program interface has been changed for novice users;
• You can work from any computer device, it is saved on a USB flash drive, leaves no traces on any system.

The image is printed only on glossy paper; you can use various booklets that are distributed in metro crossings and shopping malls.

Some radio amateurs use thin, glossy photographic paper - in this case, the print is better.

It is necessary to print at the maximum, then the copy will be of high quality - the entire drawing should be clearly visible. After that, we put it on a fat-free board and iron it with an iron set to the third power position for several minutes. For photographic paper, half a minute is enough.

Then it is necessary etch- for this we use a solution of ferric chloride, which is considered by experts to be the best option. With the help of acetone, we clean the copper paths from the remaining paint and start tinning them. For everything to work out well, it is better to use the Rose alloy, which was invented by a German chemist - which is why he is named by his last name.

The composition of the alloy: tin and lead, 25% each, and the rest of the volume is occupied by bismuth - its vapors are extremely toxic, so the whole process must be carried out in a well-ventilated area.

We lower several granules of this alloy into a prepared container with water (always with a flat and even bottom) and wait for them to completely melt. Then we put the plate with the pattern down and drive it along the bottom with the melted granules. With a soft sponge, remove stains and excess nodules on the tracks.

Amplifier installation

In order not to confuse anything, we apply on the reverse side using the same technology. wiring diagram... After drilling the necessary holes in the board, we begin the installation of all parts. In the photo, the finished board with parts is installed in a prepared case.

Before attaching them to the case, it is necessary to apply markings on the end panels - for this you can use the Photoshop program, where it is easy to draw any composition where the names of the nests and all the necessary designations will be. Then we make a printout of the drawings using a printer on a thin, glossy photo paper, which we glue on panels with already made technological holes and treated with acetone for degreasing. We use joiner's glue.

The panels must be placed under powerful press weighing about 20 kg for 24 hours so that the gluing quality is perfect. Then we laminate the surface of the panels with a special thermal film using a home iron and a sheet of clean paper.

It remains only to install the cover and side panels on the case - and the amplifier is ready for use. Testing the product showed that the amplification of the sound is excellent: the sound is quite clear, and if you listen to high-quality recordings, then it can even be described as crystal, which is very good for a homemade device. All instruments are heard, the bass is excellent without rattling, and the volume is such that you can go deaf.

Now, in terms of cost: all the costs for the purchase of parts and materials when calculating turned out to be no more than one thousand rubles, and the cheapest factory-made amplifier costs from 2.5 thousand rubles, not to mention the excellent quality of products, whose cost is estimated at several tens of thousands rubles.

We all love to listen to music on headphones, since it is not always possible to turn it on in the speakers, especially at late hours of the day or on public transport. But the sound quality itself is not always good enough, one of the signs of this is the built-in amplifier in the playback device, be it a phone or a computer, laptop. In this article I will tell you how to make a headphone amplifier with your own hands, in the assembly of which a kit kit will help, you can order it using the link at the end of the article.

In order to make a headphone amplifier with your own hands, you will need:
* Soldering iron, flux, solder
* Third hand soldering attachment
* Side cutters
* Thinner 646 or gasoline "galosh"
* Power supply with output voltage 12V
* Headphones, phone or other playback device

Step one.
This kit comes with a double-sided PCB, the quality is very good and has plated holes. Also, for ease of assembly, an instruction is provided, which shows the amplifier circuit and component ratings for correct installation on the board.

First of all, we install resistors on the board, their values ​​do not need to be determined, since they are signed on a piece of paper glued to them. Then we insert non-polar ceramic capacitors, and then polar electrolytic capacitors, observing the rating and polarity, the plus is the long lead, and the minus is the contact opposite the white strip on the case, on the board the minus contact is indicated by a shaded semicircle. To indicate the operation of the amplifier on the board, there is a place for a red LED, install the long leg in the place indicated by the triangle, and the minus-short leg in the hole with the strip next to it.

Step two.
In order to prevent radio components from falling out during soldering, we bend their leads on the back of the board. Next, we fix the board in the "third hand" soldering device and apply flux to the contacts, after which we solder the leads using a soldering iron and solder. We remove excess leads using side cutters. Be careful when removing pins with side cutters, as you may inadvertently remove a track from the board.

Then we install the rest of the components, namely a variable resistor, a power connection socket, two sockets for microcircuits, guided by the key on the case and the board in the form of a notch, as well as a socket for connecting the input and output of sound.

We solder the components, apply flux for better soldering. We also remove the excess part of the pins with side cutters.

After soldering, such a board is obtained.

We remove the remnants of the flux from the board using a brush and solvent 646 or gasoline "galosh". This is what the net board looks like.

Step three.
Now we install microcircuits in special sockets according to the key on the case and the board.

Next, we proceed to the assembly of the case, first we try it on the board and remove the protective films from the parts of the case. We fasten the four-hole threaded racks to the bottom using a Phillips screwdriver.

Next, we install a board with a side panel with holes for connection jacks on the racks.

After that, we collect the rest of the parts and fasten the top cover with screws.

On this, the headphone amplifier can be considered ready, it remains to test it.

Step four.
For full operation of the amplifier, a 12 V power supply is required.In the socket we connect the power supply through the plug and insert the 3.5 mm Jack plug from both sides, one goes into the phone, the other into the amplifier, we plug the headphone plug into the jack labeled OUT and enjoy high-quality sound. Volume control is carried out by turning the variable resistor knob.

That's all for me, this kit-set will be useful for those who want to amplify the sound in their headphones, if the device's native preamplifier is not enough, and will also give a little experience in assembling radio constructors.

Thank you all for your attention and creative success.

Buy Kit-set on Aliexpress

It happens that by connecting our favorite headphones that produce high-quality sound to an MP3 player or computer, we find that the sound in them is very quiet, which means that your player or other device does not have enough power to provide the headphones with the required volume and clarity of sound. What then is to be done? To do this, you can assemble a headphone amplifier, we suggest assembling a simple but high-quality and very beautiful headphone amplifier in a transparent case with your own hands.

When creating this amplifier, I wanted to make it unusual, I wanted to move away from the classic plastic case. Remembering that fans of modding computers often make transparent cases for their PCs, I also decided to make the case of my amplifier transparent. And as a highlight - to abandon the printed circuit board and do everything with surface mounting.

The development of the circuit was carried out in the Eagle program. This is a classic amplifier based on the OPA2107 dual opamp.

Below is a diagram of a DIY headphone amplifier:

List of required parts for the amplifier power supply:

• Power connector;
• 5mm LED (any color);
• R1LED - resistor rated from 1K to 10K (1 W);
• CP1, CP2 - electrolytes 470 μF (for a voltage of 35 or 50 volts);
• RP1, RP2 - 4.7K (1W);

Amplifier Parts List:

• IC1 - OPA2107 dual operational amplifier; (note - on the schematic diagram, the operational amplifier is designated as OPA2132, the fact is that at first I planned to use it);
• C1L, C1R - 0.68 uF 63 V (for input audio signal);
• C2, C3 - 0.1 μF (film, to stabilize the operational amplifier);
• R2L, R2R - 100K (0.5 W);
• R3L, R3R - 1K (0.5 W);
• R4L, R4R - 10K (0.5 W);
• R5L, R5R - jumper (optional);
• Stereo jack - 2 pcs;

Since I decided to do everything by hanging installation, I started making the frame. Here you need to be careful and attentive, because the case will be transparent and any imperfections will be immediately visible.

For the power rail, I used 1mm thick solid copper wire, taken from cable cuttings used for household wiring.

Any transformer power supply with a voltage of 12 volts and an output current of 300 mA or more is perfect as a power supply. It is advisable to use a transformer PSU, since the use of impulse power supplies can lead to interference (a constant hum in the headphones will be heard).

For the power connector, I used the following connector: (the center pin is the power plus).

In order to form the same leads of resistors and wires, I used a regular screwdriver. You can use different diameters for larger or smaller radii.

Below you can see the layout of the power supply. At the input of the power supply 12 Volts, which are then converted into +6 Volts and -6 Volts using a voltage divider (resistors RP1 and RP2, 4.7 kΩ each). The point is that the op-amp requires a bipolar power supply. The wire in the center is the so-called "virtual ground" and should never be connected to real ground (at the power connector).

Two large capacitors of 470 μF 50 Volts paired with capacitors of 0.1 μF are necessary in order to reduce pickup on the op-amp and increase the stability of its operation. To do this, you need to try to arrange them as close as possible to the outputs of the op-amp.

Here are a few more photos from different angles, which show how I performed the editing.

After you have finished the soldering, you can start checking the amplifier. A small tip, you don't need to use your coolest headphones for testing, some simple ones are enough. The fact is that if you get confused somewhere and soldered the parts not according to the scheme, then such an option is quite possible in which you ruin your headphones. But I hope that when you check it, you will be fine.

Before filling this circuit with epoxy, you need to close all the slots of the connectors from getting it inside. I took the audio jacks from an old Sound Blaster Live sound card, these jacks do not contain unnecessary holes and therefore they are easy to protect from resin penetration. For a start, from the side of the contacts, I smeared the junction of the contacts with the case with a small amount of epoxy resin.

I covered the holes for the jack with the special BLU TACK plasticine and additionally sealed it with tape.

Since the amplifier will be filled with epoxy in the future, I decided to raise it a little so that when pouring it would be exactly in the center of the case. To do this, I soldered small pins from the bottom.

I thought it would be nice to refine the design of the amplifier a little more, so I decided to print stickers for the audio connectors. I prepared them in Adobe Photoshop, then printed them on thin photo paper and glued them to the connectors with double-sided tape.

For some time I have been thinking about the design of the body and the material from which the fill mold will be made. I opted for 1.5 mm plastic, it is perfectly cut with an ordinary stationery knife, while leaving a very smooth edge.

Then I designed a fill shape using the same Eagle. Having cut out all the parts, I proceeded to the assembly. In order to facilitate this procedure, I first grabbed all the corners with super glue, then glued each seam 2 times, which ensured complete tightness.

The easiest way to find out the volume of epoxy to pour is to fill the mold with water, and then pour the contents into a cup and find out the resulting volume and weight. Of course, you can measure the volume with a ruler - but the method with water seemed easier to me.

For pouring, I used a transparent epoxy resin "Polycraft DSM Synolite" + MEKP hardener (from 1 to 2%). For this particular resin, the ratio of hardener to resin should be 1:50. It was quite difficult to measure out such a small amount of hardener, a jewelery scale came in handy for this. In general, for different brands of epoxy resins, the ratio of hardener and resin is different, see the instructions.

The mixed resin must be poured slowly down the side of the mold to avoid bubbles. In the picture below, you can see that when pouring the resin, I poured a little more than required, the resin does not pour out at the same time due to the surface tension. This is because the epoxy resin hardens slightly in size.

When the epoxy hardens, there is an abundant release of heat (in my case, the temperature was 62 degrees). The mold is then covered to prevent dust and debris from entering the surface.

I left the epoxy to harden for a day. After this time, it dried up and I proceeded to remove the form. For this I used a belt sander.

Then, using a router, I grinded off the chamfers and all sharp corners.

To polish the case, I first used 600-grit sandpaper, and the final polishing was carried out "on wet" with 1200-grit fine-grained sandpaper.

And finally, here are a few more photos of the finished do-it-yourself headphone amplifier:

Now you know how to make a headphone amplifier with your own hands.

March 5, 2012 at 09:09 AM

Headphone amplifier, slightly more complicated

• DIY or do it yourself

High-tech housing made of electrical tape. Initially, the board was made for a heat shrink tube - but literally a millimeter was not enough, it did not fit. Well, nevertheless, I like it.

The price of the issue

Piece of one-sided PCB: 2 rubles
MAX9724 - 7.78 rubles
4 resistors - 0.07 * 4 = 0.28 rubles
Capacitors - 0 (even if you buy, ~ 30 rubles max.)
Connectors - 0 (if you buy, ~ 20-30 rubles)
Insulating tape for high-tech housing - 1 ruble

Total - this is exactly 11.06 rubles for me, and about 61.06 rubles if you buy everything :-)

results

Of course, I immediately stumbled upon a known problem: when working with audio, you cannot connect to the same ground in two places (USB ground and audio jack ground). In this case, noise will creep along the ground, which cannot be filtered out, and no power stabilizer will help here. (The problem is that USB has its own ground level, sound has its own, and our board has its own. Depending on the current consumed, the ground rises everywhere in different ways and this gives an irreparable interference).

You can solve this problem either by getting rid of the audio connection (USB DAC) or power supply (battery or other power supply). I was completely satisfied with the use of a power supply with a USB output due to the fact that they are everywhere and are standard.

The end result is beyond expectations. No complaints about the quality, absolute 0 noise, comfortable volume level - from 22 to 40%, and a margin for "pulling" quiet recordings. The sound is tastier (the main thing to remember is that the bass is from 0Hz) and all that, and in general - do-it-yourself audio devices always sound especially good :-)

From ready-made Chinese devices (like the same FiiO E3), they are distinguished by a lower price (sic!), Assembly with components "with a margin", the absence of capacitors in the audio path, high power when working with high-impedance headphones (300 Ohm) due to the higher supply voltage and the sound quality in theory promises to be higher (in practice, I probably would not have heard the difference).

PS. As I mentioned above, an amplifier is needed not to spoil your hearing with ultra-high volume (not to mention torn headphones), but to pump “heavy” headphones with low sensitivity if the sound card output is too dead. Well, to pull out quiet records / films without software ...

PS2. The gap between pluses and "added to favorites" is 4 times, a record :-)

Not all sound cards can provide loud and high-quality sound, and then a headphone amplifier will come to your rescue. The reason for assembling the headphone amplifier may be insufficient volume (the main reason), or poor sound quality (large distortions in sound / music). To increase the volume and sound quality, it is enough to simply connect an additional output stage in series with the sound card, which we see in the diagram below:

The harmonic coefficient with a linear frequency response from 20 Hertz to 20 kHz of such an amplifier is only 0.1% and such an amplifier can be used not only for the sound card of a computer, but also for low-power devices such as radio, mobile phone, mp3 players, laptops and netbooks ...

Let's go through the diagram now. In such a 2-stage ULF transistors with a lower level of intrinsic noise are used, which affects the quality of the amplifier. Any transistors can be used, the main thing is that the p-n-p or n-p-n transitions coincide and the powers of the transistors are the same and the T2 transistor must be installed on a radiator with an area of ​​5-8 cm2, because at rest, a current of 120 mA passes and will heat transistor T2, which can lead to overheating or even burn out. (for example, T1 can be put on KT361, KT3107, and T2 can be put on KT805, KT815). As a heat sink, screw on any aluminum or copper plate to ensure good heat dissipation. For more powerful amplifiers, you can use a cooler that will cool the radiator. The feedback circuit consists of elements R6, R7, C5. Transistor T2 operates in a class A mode. Resistors R1 and R2 must be at least 2 watts, the rest of the resistors are 0.25 watts.

Now let's look at the power supply to power the amplifier. If you are going to power from the mains, then you will definitely need to assemble a power supply unit (power supply). A transformer with any small secondary current of at least 250 mA and a secondary voltage of 16-24 volts. Next, we assemble a voltage rectifier, which can be assembled from any 4 diodes that are designed for currents of at least 250 mA and a voltage of 25 volts (but is it always better to take with a margin?). And you can buy a ready-made diode bridge on the radio market. Next, after the diode bridge, we assemble the voltage regulator. A voltage stabilizer is needed so that during bass the sound in the headphones does not sink, i.e. so that the voltage does not jump and the sound is not distorted. Transistors set any average power, for example: KT805, Kt817, KT815, KT803. We must attach the transistor to the radiator. Further, capacitors C4, C5, C6 serve as a filter that removes noise. Resistors R4 and R5 play the role of limiting the current to the base of the transistor, thereby setting a certain gain. To the base of the transistor, we see zener diodes. If we need a voltage of 15 volts at the output, then we put the zener diode at 15 volts, if at 20 volts, then we set it at 20 volts, but in this case at 15 volts. We see 2 zener diodes of the D814A brand, which are connected in series and each of which is designed for a voltage of 7.5 volts (that is, in total we get 15 volts (7.5 + 7.5 = 15)). Also note that the voltage supplied to the zener diodes must exceed 1-1.5 volts for their normal operation. The power supply diagram is below:

If you want even better sound quality, then I advise you to put together another small, very simple circuit, which is called the tone control. The tone control will help you adjust the music / sound when listening (for example, you can add more bass or, on the contrary, remove them altogether, and so you can do it with any frequency). The frequency control depth of such a circuit is 20 decibels. An additional transistor stage (transistors KT315, KT342) is introduced into this circuit, which compensates for the voltage loss for the normal operation of the amplifier. This circuit will be powered by a stabilizer that powers the amplifier. You just need to connect the power wires of our circuit in parallel to the power supply wires of the amplifier. Resistors of 47 kOhm, if for stereo, then double. An additional resistance will need to be installed at the output, since the output is very sensitive and we must extinguish this sensitivity. We select the resistor in the range of 10 ... 150 kOhm to the highest quality sound. Timbre block schematic diagram:

Now we connect the timbre regulator in the sound card, after the timbre regulator we connect the amplifier and from the amplifier we go to the headphones)) The amplifier does not require any adjustment - everything works at once! And most importantly, the wire that goes from the sound card to the amplifier / tone control, this wire must be shielded to reduce background sound. Shielding is a wire that is surrounded by a metal mesh. We put the positive wire inside, and screen the plus with a minus, i.e. minutes we solder to this grid.