Best homemade hi fi power amplifier. Laboratory of Snow leopards - Soft steps to the heights of knowledge and skill - Lab. Dual triode tube preamplifier

This article is about how to assemble an amplifier for 3,000 rubles that combines the best qualities of these two beauties in the photo below...

Of course you recognized them...
More recently, I had two of the most prominent representatives of Soviet amplifier construction - Odyssey U-010 stereo Hi-Fi from 1987 and Brig-001 from 1983.

And two more less bright, but more common - Amfiton 202 and Electronics 50U-017, which are also presented in the pictures below.

Plus, there were Odyssey 001, Rostov MK-105S, TDA 2004, TDA2030A, TDA2050, TDA7294, all included as standard.

Now I no longer have any of this...
But there is this article in which I will tell you why. First things first, the most interesting stuff is usually at the end.

Over the course of a year in my city, I bought more or less working Soviet amplifiers, restored them and listened to them, hoping to find one that would satisfy me with sound quality, assembly, design, and I simply liked it, and I describe the results of my searches in this article.

So...
- old, manufactured in ’75, but this grandfather knocks 30GD out of the basket like it’s not 30 watts / 4 ohms according to the passport, but all 100, seriously, I was stunned by what he does with the low-frequency driver, and this is probably the only thing I care about he liked it, but no, there is something else - he is 37 years old and he works!!! The distortion factor is 1% and it is noticeable, although the sound is not soapy - there are so many highs that you can pull out the high-frequency speakers with such an amplifier, and the bass is quite unique due to germanium transistors. Paired with the S30B, it definitely plays better than budget Svens, and besides, it is truly retro in wood and with good assembly. I liked it.

Rostov MK-105 S- this is a tape recorder, the power for the S90 is just right, it was supplied with them, the sound is very good, and with these speakers, soft bass, good design, beautiful dial indicators, but even when replacing all the capacitors, hissing remains, this is due with a long path of the audio signal to the power amplifier (via the input amplifier, tone block, playback amplifier), moreover, the signal circuits are not shielded, but if you turn up the volume this drawback is no longer audible. I liked it.

Amphiton 50U-202- probably like any amphiton of a similar model range (25U, 35U) it is not suitable for high-quality sound reproduction, no matter what you do with it, there are no highs, or if you turn it up, they are distorted, instead of bass there is a hum, and if you turn on the loudness, then the active subwoofer filter is ready) ). The device is distinguished by its simplicity and reliability, even excessive, probably many users of this amplifier have ever had the thought of replacing one resistor in the protection in order to reduce sensitivity. It is of interest only as a case with good radiators for installing TDAs, for example. Didn't like it.

Electronics 50U-017. Electronics, as the flagship of Soviet electronics, loved to make watches and calculators, so they would continue to do so... I have never seen such sophisticated circuitry, it feels like they crammed everything they could into it, as if they hadn’t installed a processor yet)), but somehow the sound is positive this had no effect, noisy, incorrect due to the electronic switch and the same unshielded long signal loops as in Rostov 105, the tone controls are too sharp, with increasing power the distortion increases too much, but the loudness compensation is unusual, as if pressing, deep, and a nice indicator, however The main thing is the sound, but it’s not very good. Didn't like it.

TDA 2004- if only it were...

TDA2030A– well, so-so, but you can fry something or someone on its radiator)).

TDA2050– that’s already something, I overclocked it to 50 Watts/4 Ohms, it held up, the sound is pretty good if you don’t listen too closely, because... The detailing is typical microcircuit, i.e. soap, but I liked its soft bass tonality and reliability. In my opinion, the best choice for listening to music without bothering you at no extra cost. There was an idea to make active S30s with it, I think they would work well together. I liked it.

TDA7294– I won’t write much, everyone knows everything, the microcircuit is very popular. I liked it because of the price/quality ratio, probably only the LM3886 is better in sound, but at least in our country it is twice as expensive. The detail is higher than that of the TDA2050 and in comparison with it the sound is colder and sharper, possibly due to more pronounced high frequencies. Although, if you don’t find fault, the TDA7294 is quite suitable for the S90 as an amplifier for listening to pop music at an RMS power of up to 50 Watts, higher than that it’s no longer hi-fi... Until I bought the Odyssey-010 it seemed okay, now I can’t perceive it well.

Before moving on to the best ones, a few words about how I listened. For listening I used an HD Audio sound card, a bitrate of 320 and music of different styles, here are just some compositions:
Dj Matisse & Lounge Paradise - This Love (Maroon 5 Cover);
DJ Shah feat. Nadja Nooijen – Over and Over (Original Vesrion);
Lesopoval – Ya kuplu tebe dom;
Wicked DJs - Disco Rocker (Picker Remix);
Stas Mihaylov – Koroleva;
Tritonal Ft. Cristina Soto - Forgive Me, Forget You (Triple Mash Intro);
Eva Polna – Luby menya po francuzski (Fonzarelli Chill Out Acoustic Mix);
Dire Straits - Money For Nothing (Album Version).

The speakers are my favorite S90, which I naturally modified; the essence of the modification should probably be entered as a standard in the GOST register, but I will once again list the main treatment methods:

• Coating seams with sealant
• Treatment of the internal surface with rubber-bitumen mastic
• Pasting the inner surface with synthetic padding (ideally, of course, with felt, but I just couldn’t find it anywhere in the city, and I don’t want to cut felt boots, and I can’t get by with just one pair)
• Damping the mid-frequency speaker or replacing it with 6gdsh - by the way, I didn’t find that either, so I sealed the basket windows with 15gdsh foam
• Replaced the wires with thicker ones
• I painted the grilles with glossy black enamel and covered them with wood-effect self-adhesive
• I laid a couple of bags of cotton wool
• I want to put them on tenons, but I don’t have time to sharpen everything, and I think this will be the final point of improvement, I can’t get more out of them.

And now they really sound!!!
And now about the best.

Odyssey U-010 stereo Hi-Fi– brutal, quite a solid thing, 16 kilograms of non-ferrous metal.
In addition to its attractive appearance, it has two advantages - power and bass. If you measure root mean square power according to the RMS standard, then at 4 Ohms I squeezed out 183 Watts, at 8 Ohms 120 Watts, beast)). Probably everyone has had this feeling when you are driving our domestic car and accelerate to a hundred and then slow down, because... it seems like it’s about to fall apart, and then you get into a foreign car, you give it a little gas, and it’s already 60, a little more 100, but everything is comfortable and the speed is not noticeable, about the same here, I crank it up to full, so that the sound wave moves in the bass T-shirt, but the sound is not distorted, it is almost the same as when the volume knob is on two, although the power for the speakers is already dangerous, the music does not turn into a coherent set of sounds, well, except at the very maximum, I really like it.

By the way, by the way, you can also say about it “a bucket with nuts.” The parts are random, the wires of the power supply and output transistors are thin, there is no shielding, the soldering and PCB, to put it mildly, are not the best, while I was resoldering the capacitors, several tracks came off, I had to lay the wires.

A preamplifier for a device of this level is terrible, when all the knobs are at zero we already hear a slightly different sound and only by connecting the signal directly to the PA plug can we talk about quality, although this preamplifier is interesting with such a unique thing as “frequency response balance”, discrete controls and many functional buttons .

The power supply is great! Although the transformer is humming, I filled it with paraffin - it didn’t help, but it’s so powerful and tightly assembled. A distinctive feature of this amplifier is the presence of a voltage stabilizer, in general a unique thing in Soviet amplifiers, as well as the balance of the frequency response. The stabilizer allows you to maintain a constant voltage level on the power amplifier +/- 37 Volts even at high volumes. The voltage drop, according to my measurements, was only 0.6 Volts! This largely explains the good sound quality at high powers.

The protection allows you to work not only with an 8-ohm load, but with a 4-ohm load, however, at a volume of more than half you need to be careful, when the output is shorted, the protection does not help, AND YOU DO NOT NEED TO CHECK FOR ME!, although on the other side they fly out for some reason - then transistors like KT502 are in the stabilizer, and a couple of KT818/819 outputs in the PA remain unbroken, strange.

Despite the shortcomings of the performance, of course, it is worth noting the sound, it is good, or rather the bass - it is clear, even a little rough, but quite deep. I love progressive house, tech, electro - it’s great for such styles, which can’t be said about pop and classical, it doesn’t have enough highs by default (the initial problem is in the tone block), you have to turn them all the way up by hand, then you can hear the cymbals well, the mids so himself and in this he will clearly lose to the next one.

Brig 001– a copy of 1983, the second version of the circuit design with one op-amp in the power amplifier. I read somewhere that the first copies were installed on personal orders in the offices of officials of the CPSU Central Committee, who loved good sound and who then listened exclusively to Japanese Marants and Technixes, which were naturally not available to ordinary citizens. However, the brig was not available to everyone, since its price at that time was about 600 rubles, while the same Odyssey -010 later cost 350.

Of course, the brig is the best, the best of the Soviet ones of that time, there is a lot of controversy and discussion around it, but few improvements, this means that for some it is already not bad, but not for me. It is undoubtedly very reliable and stable, and also well assembled, I had a copy with military acceptance parts. In general, it is not particularly repairable due to the fact that all the main components are connected not using plugs and plugs, but with wires and soldering, however, unscrewing any board is not particularly difficult, but to remove it you will have to solder. The quality of PCB and soldering is excellent. The number of electrolytic capacitors is probably even smaller than in all amplifiers described earlier.

About sound. This is an amplifier for chanson. And restaurant music, which I also love, it’s a great pleasure to listen to it, in general, everything with vocals and live instruments, classics, jazz. Sparkling highs, good mids, vocals and good lows, judging from this sequence it is easy to conclude that this is the opposite of Odyssey 010, plus I would add to this statement that listening to the brig through a plug, bypassing the preamplifier, I would not say that it impressed me , rather, on the contrary, the beauty of sound emanating from the brig is largely due to its timbre block.

Many people like its soft bass, personally I don’t, because when listening to electronic or heavier music at rated power, all that soft bass becomes mush.

It turns out that each amplifier is good in its own way, there is no universal one...

Of course, after reviewing all the options, only the last two remain, but they are not alike, heaven and earth, double bass or cymbals, bottom or top, choose who you like. We are all different and the technology is different, some have hearing, some don’t, some can listen to a Chinese radio at the dacha without worrying, while others are not satisfied with a home hi-fi system for a round sum and want something more , people are starting to switch to tubes...or spend a lot of money on branded audio equipment. And probably for the average listener, happiness lies in the balance of price and quality, so as for the sound of Soviet amplifiers, it is not bad, after replacing the capacitors, correct ground wiring and shielding, adjusting the quiescent current, replacing some parts with imported ones, increasing the power of the supply transformers or replacing them toroidal...etc., so many things!

I want the bass of an odyssey and the vocals of a brig, combining the best qualities in one device. Is it really necessary to take and solder one to the other? What should a person do who wants to immerse himself in the world of good sound without much hassle and expense?

My answer is to accumulate the same collection, bring them to mind, listen to them again, make sure that there are no ideal Soviet amplifiers, just as there are no ideal women, be disappointed and sell everything!

And assemble it yourself!

And in a hardware store you always pass with a smile people who choose a beautiful Chinese stupid box with an incredible number of tulips on the back panel and a price equal to their salary... when, right at home, there is an amplifier that is awesome in sound, simplicity and cost, capable of both performance and sound make the Chinese receiver smoke! I offer an amplifier that has both high and low, in which everyone will definitely find a part of the brig and the odyssey for themselves and hear for themselves what they want, as I did!

What kind of amplifier is this?

Is this Radiotekhnika U-101?!

In general, Radio Engineering was probably simply created so that one day it would be “raped”... it is beautiful, even now its ergonomics and design excite the inquisitive minds of radio amateurs whose hands are itching and it only has 20 watts - this is too little to resist. We will take it as a very convenient platform for implementing our own ideas in the field of good sound for the home.

From many different schemes, I chose those that at the moment, in my personal opinion, are optimal in terms of price/quality ratio, I will say right away that I did not make any changes other than those described in the original schemes, everything was done as it is. I won’t talk for a long time about the blocks themselves, I’m not a radio engineer to explain where things are happening, I’m an ordinary radio amateur, so read the detailed information at the links provided. I am in no way copying circuits, nor am I encroaching on the copyrights of people - radio engineers who spent time and money creating these circuits. This is a collection, a collection that is quite enough to satisfy the average listener who does not want to pay crazy money for who knows what. This amp really plays!

So, let's begin.

When I finally got under its cover... I was horrified, the wires from the trance were charred, the parts in the power amplifier were soldered in an unclear way, some were soldered in with only one leg, when turned on, the rectifier diodes got very hot and smelled of smoked resistors)). The indicator did not light up. But outwardly it was well preserved. A wonderful example - just what I wanted for a remodel.

Complete dismantling began, as a result of which I left the transformer, tone control, indicator, and input switch.

Photo of the insides (this is not my copy, everything is still good here).

We need it so that there is no hole on the back panel and so that there is a socket for entry. The socket above which “record” is written is free and there are no tracks on the board going to it; we solder a shielded acoustic wire leading to the preamplifier to this socket. This will be the line input. We immediately connect the mass with wiring to the amplifier housing; for this purpose, there are special petals on the frame; if this is not done, there will be noise.

Also, the switch board can serve as a platform for mounting the protection board; to do this, we take out the phono preamplifier box, thereby freeing up space and install the speaker shutdown relay, which is part of the protection circuit, on liquid nails, and mount the board itself next to it.

For example, I managed to clamp the heatsink of the output transistor of the protection circuit between the blades of the fuse socket.

We change electrolytic capacitors. Let's tidy up the wires.

Because I pulled everything out and had to figure out which wire goes where.

If you look at the XP7 socket, the one that is inserted onto the display board, then contacts 10,11,12 go to the filament and are soldered to the corresponding terminals on the transformer.

Contacts 5-plus power, 6-minus power, 4-common are connected to the preamplifier power supply before the stabilizers, it will be shown below how.

Pins 2 and 3 are connected to the outputs of the right and left channel power amplifiers.

To power the power amplifier, I took a toroidal transformer with two identical secondary windings of 20 Volts each with a power of about 100 Watts and bolted it to a metal substrate at the bottom of the amplifier housing, having previously drilled a hole of the required diameter in it. Next to this trance we place the power amplifier rectifier. As a diode bridge, we take an imported KVRS 5010. We assemble a block of 6 capacitors of 4700 μF x 50V, 3 per arm, and shunt it with two 1 μF film capacitors. The scheme is standard and does not need explanation.

The preamplifier, indicator, protection and switching will work from the native trance.
On the original transformer, pin 6 is the middle point, and a voltage of 16.3 V comes out from pins 5 and 5; we connect these contacts with wires to the stabilizer circuit (pins 5-6-5).
And they also provide power for the indicator.

To power the protection circuit we make a separate rectifier, because when connected to an existing preamplifier power supply, noise and low-frequency hum arise, which I could not overcome even with a 10,000 uF capacitor. But here another problem arose - the protection circuit works with a voltage of about 24 Volts, which means that about 16 Volts must be removed from the transformer before the rectifier, however, when measuring the voltages of the remaining windings of the original transformer, the minimum that I found was 37 Volts between terminals 4 and 4', I had to and use them, because a third transformer would be too much. After the rectifier, the voltage was reduced by a chain of a 5-watt 1-kohm resistor and 3 D814 zener diodes connected in series. Of course, everything could have been done more professionally and a suitable stabilizer could have been selected, but everything works that way.

This protection circuit is quite popular, so I find it difficult to indicate the original source; a similar circuit is in the brig001 amplifier from the very first edition. One thing I can say is that before this I assembled two more similar circuits, but designed for bipolar power supply and was dissatisfied with their work, the problem was that no matter how I configured and selected the ratings of the parts, the voltage at the contacts of the relay coil did not drop to that level in which the contacts connected to the speaker would open, but here everything is simple and reliable. Turn-on delay is about 2 seconds. During the preliminary check, I connected two AA batteries between the common wire and resistor R1, thereby making sure that even at three volts of DC voltage the circuit works, clicks the relay and turns off the acoustics. Switch S1 is placed on the front panel (mine is to the right of the indicator), it can also control turning off the speakers. Any transistor VT3 that is more powerful from the KT 815, KT 940 series, etc. It gets hot, we put it on the radiator. The board was not created for.

Preamplifier

I wanted to keep my original one, I have it with a version on three microcircuits, but the SP-3 resistor with loudness wore out all my nerves with uneven regulation and rustling, although after filling it with machine oil the situation improved, you need to understand that this is still an emergency measure, but to find one a new one is probably no longer possible even at the manufacturing plant itself, as well as the plant itself...

In addition, the level of noise and distortion of the native tone block was high; I connected it, as many advise, bypassing the first microcircuit and still threw it away. Although as for the sound, I liked this pred, the bass is deep, there are highs and in general it sounds somehow pleasant. However, we are assembling real Hi-Fi and therefore we don’t need any artificially created amenities; we need a tone block that, by default, does not introduce audible changes in the sound.

I once assembled it on a TDA1524 - horror, the distortion coefficient is about 0.3%, that’s a lot, no matter how I didn’t center the resistors or select the capacitors - the microcircuit still makes changes to the sound, it will only work as an active filter for the subwoofer.

I read about Solntsev's pred, which, in addition to good characteristics, also has good reviews, but did not collect it, because... there is a need to use a resistor with loudness compensation, which cannot be found in a normal state, and besides, the preamplifier is built on the same Soviet element base, from which I have already moved away to imports.

I assembled it on LM1036 - all the same problems as with TDA, but the distortion coefficient, according to some sources, is about 0.05%, this is already better, and it sounds much better, although cheaper than TDA and still not the same, not Hi- Fi.

And then I assembled a preamplifier using three NE5532 op-amps - class, when the knobs are in the center, it’s as if there was no tone block at all - this is what I wanted and was looking for! For some reason I didn’t find a mode of linearity of the frequency response, harmonic coefficient for these datasheets in the datasheet, but there is data that is 0.007%. It’s bad that there is no loudness compensation and its implementation is possible, again, with a special resistor. This is exactly the tone block that will go into my complete amplifier. This diagram was taken from a foreign site at this link.

I don't think there's much to explain here

I couldn’t find the board online, so I had to develop it myself. The board was not created for laser-iron technology; I make boards the old fashioned way with a marker and etching in ferric chloride.

Amplifier

But here it is, the hero of the occasion, which captivated me with its sound and cost, the power amplifier

I won’t write anything here, probably no one can talk about it better than its creator, whose article you can read

On my own behalf, I’ll just add that at a voltage of +/- 27 Volts, the rms power when supplying a sinusoid with a frequency of 1 kHz at a 4-ohm load was 104 Watts and also - I haven’t heard anything better yet...

About the assembly

In the Radiotekhnika amplifier, the tone block resistors were soldered into the preamplifier board itself and fastened with nuts to the bar, which in turn was connected to the housing. To install imported resistors into the same holes in this strip, you need to drill holes for the resistor protrusion with a diameter of 3 mm as in the pictures. This will provide a guarantee against rotation, besides, this protrusion is formally the middle of the resistor horseshoe, so it is necessary to drill holes as evenly as possible horizontally. We secure the resistors with nuts on the reverse side.

Disabling the tone block in my preamplifier is done using a relay, which I powered in the same place as the protection board; the tone on/off button is located on the front panel (on my left).

After removing the main internals, I also removed the “input copy” and headphone jacks, leaving holes on the front panel, which is not very nice. In this case, I used Soviet non-polar capacitors of the K50-6 type, wrapped with adhesive tape in one layer, which fit very well into these holes, now it looks more like buttons.

The most difficult part of mounting power amplifiers was installing them on radiators. It was necessary, without bending the legs of the transistors too much, to attach them to the radiator, naturally through a layer of thermal paste and mica or thermal rubber, as in my case. To do this, drill holes between the ribs in pre-marked places. Because I didn’t hit it exactly in the middle - I had to grind down the bolt heads perpendicular to the groove for the screwdriver, which in the end was also the best option, because resting against the rib when tightening the nut from the reverse side, the bolt does not turn.

Do not connect the common wire of the power amplifier power supply to the housing frame directly as a preamplifier! A low-frequency hum appears, which is precisely why the problem with the power supply of the protection remained unresolved, because When connecting the common protection wire to the common wire of the power amplifier, a slight hum also appears. Therefore, the protection circuit currently functions only as a turn-on delay circuit; in this mode there is no unnecessary noise.

As a coil in a power amplifier, a coil from Holton, Radiotekhnika’s own powerhouse, was perfect.
When assembling, do not skimp on insulating tape, flux and solder.

Economy

• Dead radio equipment 150 RUR
• Transformer 2x18 Volt for PA, which is especially nice, produced by our TopTransform plant in Rybinsk 700 RUR
• Diode bridge and power amplifier capacitors 410 r
• Preamplifier for NE5532 530 RUR
• Protection board and relay 130 RUR
• UM stonecold 300 r one channel, i.e. stereo 600 RUR
• Manufacturing of circuit boards - textolite, solder, flux, ferric chloride, drills, felt-tip pens 165 RUR
• Buttons, wires, plugs, capacitors for indicators, etc. 125 RUR

It turns out 2810 rub.

Impression

The first thing that catches your ears is the detail of the sound! A good stereo panorama, but as described by the creator of the stonecold, not into space, but for the listener. Many people complain about the S90 because of its poor midrange, but when playing with this amplifier, this drawback is compensated by a more pronounced midrange and excellent vocal reproduction; the highs are also quite sufficient. As for the bass, everything is fine here too, it is clear, but not harsh.

Here you have Odysseus and Brig, all in Radio Engineering. The radiators of the pre-output transistors are warm, the radiators of the output transistors are cold, that’s how it should be!

The power, as I already said, is 100 watts at 4 ohms, there is no way to measure the distortion coefficient, but I think it is small and if compared with the Soviet ones, then 0.01% or even less, at least at high power it plays even cleaner than the Odyssey 010.

I am very pleased, firstly with the sound, secondly with what I did myself, and thirdly with the price-quality ratio.

To finalize everything written above, I will say that with great enthusiasm throughout the year I have been buying Soviet equipment in search of something that will stand on my windowsill and delight me with its sound, but time does not stand still and if once these things cost decent prices by the standards of the money and were quite satisfied with their quality, now we must admit that our civilian electronics remained somewhere there in 91 and it looks like it’s not sad that it remained there forever... We must pay tribute to all Soviet things, we still use and steal them! Now, when you go to a radio parts store, you can buy a KT3102 from 1987 (there is simply no newer one) or an analogue of the BC546, which is newer, cheaper and of better quality, naturally I will choose the second. And I’ll be honest, I didn’t want to sell the brig, I liked it, it had military-grade details, the build quality and sound were quite high, but when I assembled the stonecold I was finally convinced that the obsolescence of the equipment was not just empty words. I listen to it with the preamp turned off, I don’t need to turn up the bass until the glass rattles, everything is enough for me as is. And what is most important is the presence of a strange feeling that any song probably sounds exactly the way it should sound, perhaps this is High Fidelity!

List of radioelements

Designation	Type	Denomination	Quantity	Note	Shop	My notepad
	Preamplifier
OP1-OP3	Operational amplifier	NE5532	3			To notepad
C101, C201	Capacitor	47nF	2			To notepad
C102, C202	Capacitor	1 nF	2			To notepad
C103, C203	Capacitor	2.2 µF	2			To notepad
R101, R201, R116, R216, R119, R219	Resistor	100 kOhm	6			To notepad
R102, R202, R112, R212	Resistor	1 kOhm	4			To notepad
R103, R203, R104, R204, R107-R109, R207-R209	Resistor	10 kOhm	10			To notepad
R105, R205, R106, R206	Resistor	22 kOhm	4			To notepad
R110, R210, R115, R215	Resistor	100 Ohm	4			To notepad
R111, R211	Resistor	10 ohm	2			To notepad
R113, R213	Resistor	15 kOhm	2			To notepad
R114, R214	Resistor	33 kOhm	2			To notepad
R117, R217, R118, R218	Resistor	4.7 kOhm	4			To notepad
VR1A, VR1B, VR2A, VR2B, VR4A, VR4B	Trimmer resistor	100 kOhm	6			To notepad
VR3	Trimmer resistor	50 kOhm	1			To notepad
	Power amplifier 1 channel
OP1	Operational amplifier	TL071	1			To notepad
VT1	Bipolar transistor	BC546	1			To notepad
VT2	Bipolar transistor	BC556	1			To notepad
VT3	Bipolar transistor	TIP32C	1			To notepad
VT4	Bipolar transistor	TIP31C	1			To notepad
VT5	Bipolar transistor	TIP142	1			To notepad
VT6	Bipolar transistor	TIP147	1			To notepad
VD1, VD2	Rectifier diode	1N4148	2			To notepad
VD3, VD4, VD6, VD7	Rectifier diode	1N4007	4			To notepad
VD11, VD12	Zener diode	1N4742	2			To notepad
L1	Inductor	2 µH	1			To notepad
C1, C4, C6	Capacitor	1 µF	3			To notepad
C2	Capacitor	500...5600 pF	1			To notepad
C3	Capacitor	24 pF	1			To notepad
C5, C7		100 µF	2			To notepad
C8, C10	Capacitor	0.33 µF	2			To notepad
C9, C11	Electrolytic capacitor	220 µF	2			To notepad
C12	Capacitor	150 pF	1			To notepad
R1	Resistor	47 kOhm	1			To notepad
R3	Resistor	200 Ohm	1			To notepad
R5, R6	Resistor	2 kOhm	2			To notepad
R7, R8	Resistor	180 Ohm	2			To notepad
R9	Resistor	39 Ohm	1			To notepad
R10	Resistor	22 Ohm	1			To notepad
R11	Resistor	3.9 kOhm	1			To notepad
R14	Resistor	4.7 kOhm	1

Today we have a useful homemade product for connoisseurs of good sound: a high-quality tube amplifier made by yourself

Hello!

I decided to assemble a push-pull tube amplifier (my hands were really itching) from the parts I had accumulated over a long time: housing, lamps, sockets for them, transformers, etc.

I must say that I got all this stuff for free (you mean free of charge) and the cost of my new project will be 0.00 hryvnia, and if I need to buy something in addition, I’ll buy it for rubles (since I started my project in Ukraine, and I’ll finish already in Russia).

I'll start the description with the body.

Once upon a time it was, apparently, a good amplifier from SANYO model DCA 411.

But I didn’t have a chance to listen to it because I got it in a terribly dirty and non-working state, it was dug up beyond repair and the burnt 110 V power supply (Japanese, probably) smoked all the insides. Instead of the original final stage microcircuits, there are some snot from Soviet transistors (this is a photo from the Internet of a good example). In short, I gutted it all out and began to think. So, I couldn’t think of anything better than stuffing a lamp there (there’s quite a lot of space there).

Decision is made. Now we need to decide on the scheme and details. I have a sufficient number of 6p3s and 6n9s lamps.

Due to the fact that I had already assembled a single-cycle amplifier for 6p3s, I wanted more power and, having rummaged through the Internet, I chose this push-pull amplifier circuit for 6p3s.

Circuit of a homemade tube amplifier (ULF)

The diagram is taken from the website heavil.ru

I must say that the scheme is probably not the best, but due to its relative simplicity and availability of parts, I decided to stick with it. Output transformer (an important figure in the plot).

It was decided to use the “legendary” TS-180 as output transformers. Don’t throw stones right away (save them for the end of the article :)) I myself have deep doubts about this decision, but given my desire not to spend a penny on this project, I will continue.

I connected the trance outputs for my case like this.

(8)—(7)(6)—(5)(2)—(1)(1′)—(2′)(5′)—(6′)(7′)—(8′) primary

(10)—(9)(9′)—(10′) secondary

anode voltage is applied to the connection of pins 1 and 1′, 8 and 8′ to the anodes of the lamps.

10 and 10′ per speaker. (I didn’t come up with this myself, I found it on the Internet). To dispel the fog of pessimism, I decided to check the frequency response of the transformer by eye. To do this, I quickly assembled such a stand.

In the photo there is a GZ-102 generator, a BEAG APT-100 amplifier (100V-100W), an S1-65 oscilloscope, a 4 Ohm load equivalent (100W), and the transformer itself. By the way, there is a .

I set it to 1000 Hz with a swing of 80 (approximately) volts and record the voltage on the oscilloscope screen (about 2 V). Next, I increase the frequency and wait until the voltage on the trance secondary starts to drop. I do the same thing in the direction of decreasing the frequency.

The result, I must say, pleased me: the frequency response is almost linear in the range from 30 Hz to 16 kHz, well, I thought it would be much worse. By the way, the BEAG APT-100 amplifier has a step-up transformer at the output and its frequency response may also not be ideal.

Now you can collect everything in a heap into a case with a clear conscience. There is an idea to do the installation and layout inside in the best traditions of so-called modding (minimum wires in sight) and it would also be nice to have LED backlighting like in industrial copies.

Power supply for a homemade tube amplifier.

I'll start the assembly and at the same time describe it. The heart of the power supply (and of the entire amplifier, probably) will be the TST-143 toroidal transformer, which I once (4 years ago) tore out of some tube generator right as it was being taken to a landfill. Unfortunately, I didn’t manage to do anything else. It’s a pity for such a generator, but maybe it was still working or could have been repaired... Okay, I digress. Here he is my security officer.

Of course, I found a diagram for it on the Internet.

The rectifier will be on a diode bridge with a filter on the inductor for anode power. And 12 volts to power the backlight and anode voltage. This is the throttle I have.

Its inductance was 5 henry (according to the device), which is quite enough for good filtration. And the diode bridge was found like this.

Its name is BR1010. (10 amps 1000 volts). I'm starting to cut out the amplifier. I think it will be something like this.

I mark and cut holes in the PCB for the sockets for the light bulbs.

It turns out well :) I like everything so far.

This way and that way. drill and saw :)

Something began to emerge.

I found a fluoroplastic wire in old supplies and immediately all the alternatives and compromises regarding the wire for installation disappeared without a trace :) .

This is how the installation turned out. Everything seems to be “kosher”, the incandescence is intertwined, the ground is practically at one point. Should work.

It's time to fence in food. After checking and testing all the output windings of the trans, I soldered all the necessary wires to it and began installing it according to the accepted plan.

As you know, in our life it’s not easy to go anywhere without improvised materials: this is how the Kinder Surprise container came in handy.

And a Nescafe lid and an old CD

I tore out the circuit boards of TVs and monitors. All containers are at least 400 volts (I know that I should have more, but I don’t want to buy them).

I bridge the bridge with containers (whatever were on hand, I’ll probably change them later)

It’s a bit much, but oh well, it will sag under load :)

I use the standard power switch from the amplifier (clear and soft).

We're done with that. It turned out well :)

Backlight for tube amplifier housing.

To implement the backlight, an LED strip was purchased.

And installed in the housing as follows.

Now the glow of the amplifier will be visible during the daytime. To power the backlight, I will make a separate rectifier with a stabilizer on some KRKEN-like microcircuit (which I can find in the trash), from which I plan to power the anode voltage supply delay circuit.

Delay relay.

Having rummaged through the bins of my homeland, I found this completely untouched thing.

This is a radio time relay designer for a photo enlarger.

We collect, check, try on.

I set the response time to about 40 seconds, and replaced the variable resistor with a constant one. The matter is coming to an end. All that remains is to put everything together, install the face, indicators and regulators.

Regulators (input variables)

They say the sound quality can greatly depend on them. In short, I installed these

Dual 100 kOhm. Since I have two of them, I decided to parallel the pins, thereby obtaining 50 kOhm and increased resistance to wheezing :)

Indicators.

I used standard indicators, with standard backlighting

I mercilessly copied the connection diagram from the original board and used it as well.

This is what I ended up with.

When checking the power, the amplifier demonstrated an output voltage of 10 volts of an undistorted sine wave with a frequency of 1000 Hz into a 4 ohm load (25 watts) equally across channels, which was pleasing :)

When listening, the sound was crystal clear without background and dust, as they say, but too monitory, or what? beautiful, but flat.

I naively believed that he would play without timbres, but...

Using a software equalizer, we managed to get a very beautiful sound that everyone liked. Thank you all very much!!!

Let's consider an example of the construction and calculation of one of the circuits of audio frequency power amplifiers (abbreviated as UMZCH)

Operational amplifiers are a good thing! The range is extensive, the characteristics are excellent, the price is comparable to transistors, but the problem is that the supply voltage in most cases is ±15 V, which limits the output voltage to approximately ±10 V, the output resistance is also quite high - on the order of several kOhms. This does not allow the op amp to be used directly to drive loudspeakers. But we also have the “High Command Reserve” - powerful transistors! Only to obtain high power at the output of the UMZCH they require a fairly high supply voltage. So what? We make a preliminary stage using an op-amp with a stabilized power supply of ±15 V, and a transistor output with a power supply with an unstabilized voltage of the magnitude that only the output transistors will allow us. Why with unstabilized? There are several reasons: the difficulty of implementing a high-voltage stabilizer of sufficient power with acceptable characteristics of efficiency and quality; also because the noise and distortion introduced by the power supply in powerful stages is practically much less significant than in the preliminary stages due to the difference in the signal/noise ratio.
Let's go directly to the diagram. The UMZCH circuit is chosen to be two-way, which allows the use of op-amps with fairly low frequency characteristics. The entire circuit is actually an inverting amplifier with negative feedback (NFB) and a gain equal to R2/R1. The gain should not be chosen more than 10, which in fact, with an input signal of ±10 V, gives an output signal of ±100 V. The frequency band of this UMZCH is practically limited only by the frequency characteristics of the output stage. It should also be noted the good stability of the “zero”, due to the use of op-amps and optimal frequency characteristics.

Schematic diagram of UMZCH

Description and calculation of the circuit

To ensure that the frequency band in the amplifier is not limited by the characteristics of the op-amp, the input signal is supplied to the low-frequency and high-frequency paths. The drive signal is supplied to the emitters of the transistors VT1 And VT2, which form cascode pairs VT1-VT3 And VT2-VT4 on transistors of opposite structures.
First, let's set the collector currents of the transistors VT1—VT4 10 mA each. As a result, the current through the resistors R12, R13 should be 20 mA. As VD1 And VD2 We use LEDs with a voltage drop across them of 1.6 V (most red LEDs). These LEDs can be used simultaneously as power-on indicators. It is also possible to replace these LEDs with zener diodes or stabilizers with the appropriate stabilization voltage, but then we lose the function of indicating the amplifier's power supply.
Considering the voltage drop across VD1 And VD2, equal to 1.6 V on each and subtracting the base-emitter voltage on the transistors VT3 And VT4 we get the voltage across the resistors R12 And R13 1 V each. Hence: divide the voltage drop across the resistors R12 And R13(1 V each) for a current of 20 mA specified through them we get R12=R13=1 V / 20 mA = 50 Ohm . The closest standard resistance value is 51 ohms.
In the absence of a signal, the current through the resistors R5=R6 is approximately 0.6 V/ R6. It is this amount of current through the resistors R9, R10 must exceed the specified collector current of the transistors VT1, VT2(10 mA each).
For the most efficient use of transistor current sources VT3, VT4 it is necessary that their collector currents change from an average value of 10 mA to ±10 mA, i.e. so that their range of change is from 0 to 20 mA. Based on this, we determine the resistance of the resistors R5=R6= 10 V / 10 mA = 1 kOhm (same as standard denomination). From here we get the current through the resistors R5, R6 at rest 0.6 V / 1 kOhm = 0.6 mA, and through resistors R9, R10— (10+0.6)=10.6 mA. Therefore, R9=R10=15 V / 10.6 mA = 1.4 kOhm. We select the standard nominal value of 1.3 kOhm.
The calculation of pairing the op-amp with the final stage is now complete. Now let's move on to the output transistors.

Current protection of output transistors is provided by transistors VT5, VT6, the base circuits of which are connected to current sensors R18, R19. If the voltage at the base of the transistor VT5 or VT6 exceeds 0.6 V ( UBE≈ 0.6 V), the corresponding transistor will open and shunt the base-emitter junction of the corresponding output transistor VT7 or VT8. The output limiting current will be:

Ilim = UBE / R18 - ((Up - Uout).R16) / (R14.R18)

During operation, this current increases along with the load current when the output voltage approaches the supply voltage Up. Given that R14.R18/R16 = Rн , limiting current for any positive values Uout for transistor VT7 or negative for VT8 will be greater than the load current by the amount ΔI=UBE/R18-Up/Rн . Having set the size ΔI=(0.1...0.2)Imax and knowing the quantities Up And Rн you can calculate the resistance of the resistor R18 based on the previous formula. Size Rн should be set to the minimum possible. Next, select the resistor resistance R16 in the range from 200 to 800 Ohms and determine the resistance R14=Rн.R16/R18 . Because the circuit is symmetrical, then: R14=R15 , R16=R17 , R18=R19 .
Maximum power dissipated by each transistor VT7, VT8 in operating mode at LF with the selected protection method is: Pmax=(U2BE.R14)/(4.R18.R16)=0.25Rн(UBE/R18)2 .
Note that in emergency mode, i.e. if the amplifier output is short-circuited to ground, the power dissipated in the output transistors will not exceed (0.1...0.2)Imax.Up , and when the amplifier output is shorted to the power source, the output transistors will close altogether. Moreover, this occurs at the moment when Ilim=0 , i.e. When Uout=Up-UBE.Rn/R18 . In real conditions VT7 locks when Uout less than minus(2...4) V, VT8- at Uout more than +(2...4) V. Compared to a protection circuit without using dividers R14-R17 the applied circuit has obvious advantages: the maximum power dissipation when the output is shorted to ground is 6-11 times less, and when it is shorted to the power source it is even half as much.
Due to a drop in the amplitude-frequency response (AFC) of the op-amp, signal distortion increases as the frequency increases. Therefore, it is necessary to take measures to ensure that the HF path begins to work earlier than signal distortion becomes noticeable in the LF path made on the op-amp. To do this, the cutoff frequency of the low-pass filter (LPF) at the input of the op-amp formed R3 And C2 should be chosen around 10 kHz, i.e. R3=16 kOhm, C2=1000 pF. High pass filter (HPF) cutoff frequency R4C1 should be selected no higher than 1 kHz, i.e. R4=20 kOhm, C1=0.01 µF. The RF open-loop gain is set by resistors R7, R8. The gain must be set together with the choice of capacitance C3 = C4, so that with a closed feedback circuit of the entire amplifier, the desired type of transient processes is achieved. In principle, in this scheme it is possible to achieve a SOI value of 0.005%.
For op-amps, standard frequency correction is sufficient. When the amplifier is excited at high frequencies, it can be suppressed by introducing base circuits of transistors and resistors. In the case of an inductive load, it may be necessary to connect a corrective RC circuit and also shunt R2 a small capacitor connected in series with a resistor with a resistance of 0.1 R2. Output transistors can be composite, which allows achieving good energy and quality indicators. And let me remind you - you shouldn’t forget about the power of resistors. Firstly, it is determined by the current through the resistor - P=I2.R , secondly - the maximum permissible voltage across the resistor.

Literature:
1. Titze U., Schenk K. Semiconductor circuitry. — M.: Mir 1982
2. To help the radio amateur: Collection. Vol. 89. - M.:DOSAAF, 1985
3. Shilo V. L. Linear integrated circuits. - M.: Soviet radio, 1979

People who love good music probably know about the Hi-End tube amplifier. You can do it yourself if you know how to use a soldering iron and have some knowledge of working with radio equipment.

Unique device

Hi-End tube amplifiers are a special class of household appliances. What is this connected with? Firstly, they have some pretty interesting design and architecture. In this model, a person can see everything he needs. This makes the device truly unique. Secondly, the characteristics of a Hi-End tube amplifier differ from alternative models that use Hi-End. The difference between Hi-End is that a minimum number of parts are used during installation. Also, when evaluating the sound of this device, people trust their ears more than nonlinear distortion measurements and an oscilloscope.

Selecting circuits for assembly

The preamplifier is quite simple to assemble. For it, you can choose any suitable scheme and start assembling. Another case is the output stage, that is, a power amplifier. As a rule, many different questions arise with it. The output stage has several types of assembly and operating modes.

The first type is a single-cycle model, which is considered a standard cascade. When operating in “A” mode, it has slight nonlinear distortion, but, unfortunately, has rather poor efficiency. Also noteworthy is the average power output. If you need to fully sound a fairly large room, you will need to use a push-pull power amplifier. This model can operate in “AB” mode.

In a single-ended circuit, only two parts are enough for the device to work well: a power amplifier and a pre-amplifier. The push-pull model already uses a phase inverted amplifier or driver.

Of course, for two types of output stage, in order to work comfortably with, it is necessary to match the high interelectrode resistance and the low resistance of the device itself. This can be done using a transformer.

If you are a connoisseur of “tube” sound, then you should understand that you need to use a rectifier, which is produced on a kenotron, to achieve such a sound. In this case, semiconductor parts cannot be used.

When developing a Hi-End tube amplifier, you don't have to use complex circuits. If you need to sound a fairly small room, then you can use a simple single-cycle design, which is easier to make and configure.

DIY Hi-End tube amplifier

Before starting installation, you need to understand some rules for assembling this type of device. We will need to apply the basic principle of installing lamp devices - minimizing fasteners. What does it mean? You will need to discard the mounting wires. Of course, this cannot be done everywhere, but their number must be minimized.

In Hi-End, mounting tabs and strips are used. They are used as additional points. This type of assembly is called hinged. You will also need to solder the resistors and capacitors that are on the lamp panels. It is highly not recommended to use printed circuit boards and assemble conductors so as to create parallel lines. This will make the assembly look chaotic.

Removing Interference

Later, you need to eliminate the low-frequency background, if, of course, it is present. Another important point is the choice of grounding point. In this case, you can use one of the options:

• The type of connection is a star, in which all “ground” conductors are connected to one point.
• The second method is to lay a thick copper busbar. It is necessary to solder the corresponding elements onto it.

In general, it is better to find a grounding point yourself. This can be done by determining the level of low-frequency background by ear. To do this, you need to gradually close all the grids of lamps that are located on the ground. If, when the subsequent contact is closed, the low-frequency background level decreases, then you have found a suitable lamp. To achieve the desired result, it is necessary to experimentally eliminate unwanted frequencies. You should also apply the following measures to improve the quality of your build:

• To make filament circuits for radio tubes, you need to use twisted wire.
• Tubes used in the preamplifier must be covered with grounded caps.
• It is also necessary to ground the housings with variable resistors.

If you want to power the preamp tubes, you can use DC current. Unfortunately, this requires connecting an additional unit. The rectifier will violate the standards of a Hi-End tube amplifier, since it is a semiconductor device that we will not use.

Transformers

Another important point is the use of different transformers. As a rule, power and output are used, which must be connected perpendicularly. This way you can reduce the level of low-frequency background. Transformers should be located in grounded enclosures. It must be remembered that the cores of each transformer should also be grounded. There is no need to use it when installing devices to avoid additional problems. Of course, these are not all the features associated with installation. There are quite a lot of them, and it will not be possible to consider them all. When installing a Hi-End (tube amplifier), you cannot use new element bases. They are now used to connect transistors and integrated circuits. But in our case they will not work.

Resistors

A high-quality Hi-End tube amplifier is a retro device. Of course, the parts for its assembly must be appropriate. Instead of a resistor, a carbon and wire element may be suitable. If you spare no expense in developing this device, you should use precision resistors, which are quite expensive. Otherwise, MLT models are applicable. This is a pretty good element, as evidenced by the reviews.

Hi-End tube amplifiers are also suitable for use with BC resistors. They were made about 65 years ago. Finding such an element is quite simple; you just need to walk around the radio market. If you are using a resistor with a power of more than 4 Watts, you need to choose enameled wire elements.

Capacitors

In a tube amplifier setup, you should use different types of capacitors for the system itself and the power supply. They are usually used to adjust the tone. If you want to get high-quality and natural sound, you should use a coupling capacitor. In this case, a small leakage current appears, which allows you to change the operating point of the lamp.

This type of capacitor is connected to the anode circuit, through which a large voltage flows. In this case, it is necessary to connect a capacitor that maintains a voltage greater than 350 volts. If you want to use quality parts, you need to use parts from Jensen. They differ from analogues in that their price exceeds 3,000 rubles, and the price of the highest quality radio elements reaches 10,000 rubles. If you use domestic elements, it is better to choose between the K73-16 and K40U-9 models.

Single ended amplifier

If you want to use a single-cycle model, you must first consider its circuit diagram. It includes several components:

• power unit;
• final stage;
• pre-amplifier in which the tone can be adjusted.

Assembly

Let's start the assembly with the pre-amplifier. Its installation follows a fairly simple scheme. It is also necessary to provide power control and a separator for tone control. It should be tuned to low and high frequencies. To increase shelf life, you need to use a multi-band equalizer.

In the laughter of the preamplifier you can see similarities with the common 6N3P double triode. The element we need can be assembled in a similar way, but use the final cascade. This is also repeated in stereo. Remember that the structure must be assembled on a circuit board. First it needs to be debugged, and then it can be installed on the chassis. If you installed everything correctly, the device should turn on immediately. Next you should move on to configuration. The value of the anode voltage for different types of lamps will differ, so you will need to select it yourself.

Components

If you do not want to use a high-quality capacitor, then you can use K73-16. It will be suitable if the operating voltage is more than 350 volts. But the sound quality will be noticeably worse. Electrolytic capacitors are also suitable for this voltage. You need to connect the C1-65 oscilloscope to the amplifier and submit a signal that will pass from the audio frequency generator. During the initial connection, you need to set the input signal to about 10 mV. If you need to know the gain, you will need to use the output voltage. To select the average ratio between low and high frequencies, it is necessary to select the capacitance of the capacitor.

You can see a photo of a Hi-End tube amplifier below. For this model, 2 lamps with an octal base were used. A double triode is connected to the input, which is connected in parallel. The final stage for this model is assembled on a 6P13S beam tetrode. This element has a built-in triode, which allows you to get good sound.

To configure and check the functionality of the assembled device, you must use a multimeter. If you want to get more accurate values, you should use a sound generator with an oscilloscope. When you have taken the appropriate devices, you can proceed to setup. At cathode L1 we indicate a voltage of about 1.4 Volts; this can be done if you use resistor R3. The output lamp current must be specified as 60 mA. To make resistor R8, you need to install a pair of MLT-2 resistors in parallel. You can use other resistors of different types. It should be noted that a rather important component is the decoupling capacitor C3. It was not in vain that it was mentioned, since this capacitor has a strong influence on the sound of the device. Therefore, it is better to use a proprietary radio element. Other elements C5 and C6 are film capacitors. They allow you to increase the quality of transmission of various frequencies.

A power supply built on the 5Ts3S kenotron is worth finding. It complies with all the rules for constructing the device. A homemade Hi-End tube power amplifier will have high-quality sound if you find this element. Of course, otherwise it is worth looking for an alternative. In this case you can use 2 diodes.

For a Hi-End tube amplifier, you can use the appropriate transformer, which was used in old tube technology.

Conclusion

To make a Hi-End tube amplifier with your own hands, you need to perform all the steps consistently and carefully. First, connect the power supply with the amplifier. If you configure these devices correctly, you can install a pre-amplifier. Also, using the appropriate technology, you can check all the elements to prevent damage. After assembling all the elements together, you can begin to design the device. Plywood may work well for the body. To create a standard model, it is necessary to place radio tubes and transformers on top, and regulators can already be mounted on the front wall. Using them you can enhance the tone and see the power indicator.