It's been a long time since I wrote anything here ... Somehow, everything didn't stick.
But finally, something was found that could really be of interest to someone else besides the author.
Frankly, I pondered this topic for a long time ... I rummaged through everything on the internet that could be found about this and only realizing that there was very little really sane and useful about the topic sounded in the title, I decided to crown my efforts with an epistolary report, for which, before all armed with a camera to capture the process in all details, trying not to miss a single important moment.
So, I'll start, perhaps, from afar ..
It so happened that for more than 30 years of practice of my radio engineering "creativity", I have never had a chance to make a completely tube amplifier.
There were a lot of reasons for that!
I will not list them all. I can only say that I have dealt with lamps, and quite successfully and productively. But this was due to the pre-amplification cascades and made it possible not to get involved with hemorrhoids, due to the need to mount a bunch of pieces of iron, in the form of chokes, big trances and others like them.
But I wanted, at least once in my life, to make a classic (moreover, just a classic !!!) lamp lamp, with lamps beautifully glowing in the dark, mounted outside ...
It’s not that I don’t understand what it will result in for me ... But, I confess honestly, I didn’t realize that, in contrast to the design of semiconductor ("stone") equipment, the manufacture of a lamp apparatus should rather be attributed not so much to electronics as to plumbing work.
But I'm getting ahead of myself ...
To begin with, as I said above, without further ado, I blasted in the search engine line: “ tube amplifier with your own hands. "
However, having reached (no lies !!!) the tenth page of the search engine, I realized that the main motive of those who had already managed to tell about their experience in creating tube amplifiers with my own hands there was not a desire to teach others something, but rather a desire to boast of their own achievements, without sharing the secret of such "success" with others.
There is very little real information about HOW to do this, and if it exists, it is very scattered and sparing of details.
Actually, at that moment I realized that I was favorably left a place in this clearing. J
So why, in fact, a lamp tube?
I will not rant about fashion trends, such as Hi-End. It is clear that this is both fashionable and prestigious, and the sound of a tube really compares favorably with a transistor sound. What? ... - With this question not here! If you just want to "decide for yourself" - raise your brain to your acquaintances who have such devices, or managers in salons, such as the Purple Legion.
And if you decide that you want this, but spend on this "miracle" of the money that those who sell it usually ask for this kind of equipment are not ready (and who touches, for whatever reason you are not ready! ..) , then, probably, this article will be useful to you ...
So where do you start?
Perhaps, in this case, you can easily determine the sequence of actions!
In the case of "stone" devices, everything was somewhat different. At first, the filling was assembled there, and only then did we think about cases for our creations.
In the case of tube amplifiers, everything is exactly the opposite, since for these machines the amplifier body is, first of all, a structure that carries all the main elements. So, first of all, decide on how you would like your amplifier to look as a result, that is, decide on the case!
I must say (I know from my own practice) that this is the most difficult question in our "fatherland". Alas, in Russia, finding a decent housing for radio equipment is almost impossible to solve. L
I'm not that lucky ... But at one time I brought a lot of such iron from the "celestial". Therefore, I was lucky to avoid this problem. And I will even say more! Perhaps I can help some of you deal with this problem as well! ;) Well, yes, this is all just in private ...
In the meantime, having decided on how our creation will look like, it is worth solving the second, of the most important tasks - to decide which one to assemble from amplifiers?
There are a lot of schemes, ideas, not to mention opinions!
And figuring out on the fly which of the ideas to grab is incredibly difficult.
In such cases, it is worth starting with the simplest and, in the same place with the one, worked out not even for years - but for decades of material ...
But such, as the practice of studying the issue has shown, there is a lot.
And here, perhaps, it is worth starting to share your own experience.
There are a lot of established stereotypes in our minds. So, for example, high-speed driving in our country inevitably evokes an association with Michael Schumacher, and the racing car itself inevitably with a red Ferrari ...
Similarly, when it comes to tube Hi-End, the first thing that comes to mind for people who have already come into contact, at least to a minimal extent, with this topic is, of course, Audio Note.
For more than a dozen years, it is the Audionot sound that is almost a religion among a large part of the "sophisticated hi-end"
At one time, many copies were broken in the field of discussions about what, in fact, is this secret of sounding the creations of Peter Kvortrup (dad and one of the main designers of Audio Note).
I remember that this casket was as easy to open as most of the others.
A relatively small number of experiments made it possible to find out that the main part of the colors in the Audinotovsky sound was introduced by the first stage, usually built according to the so-called SRPP (cascade) scheme.
I did not philosophize either, having determined that it should be he and nothing else at the entrance, although something else could be simpler, but not much.
The output stage is even easier!
Here it is worth starting from the principle of accessibility. Speaking about accessibility, I mean, first of all, the element base, on the basis of which you can build something that sounds quite decent.
In this it is worth relying on the "experience of ancestors" in abundance that have come down to us in the form of the remains of old tube TVs and radio (Hello trash heap !!!).
In extreme cases, this junk, in the form of weekend (TVZ-Sh) and power (TS-180) transformers, is usually in abundance at local flea markets that take place on weekends in all areas and areas of our "immense" ...
And in conclusion, the problem of choosing an output lamp boils down to understanding that these very output transformers TVZ-Sh were designed to work with almost the only one developed in the socialist fatherland, a light bulb created specifically to amplify sound. Of course, we are talking about the legendary 6P14P or its more modern counterparts 6P15P or 6P18P.
However, your will! You can also supply a "proprietary" analogue in the form of EL 84. How much the result will be worth is up to you to judge. Here I will just note that these replacements should not entail any constructive or schematic changes. Even the modes of these lamps are almost identical and, most likely, you will not have to adjust anything with such a replacement on an already made and working amplifier.
Since we are talking about lamps, perhaps it is worth mentioning the light bulb for the first stage.
I am not afraid of the shits of malicious remarks of the "dissent", but IMHO there is simply no better candidate for the first stage than 6N23P-EB. However, I will immediately warn you that the number of people who agreed with me will be approximately equal to the number of those who objected. I will only say that if we are striving for the Audionot sounding, then this is the very thing! J
Well, actually, we have almost drawn our scheme ourselves.
To all that has been said above, it is worth adding unless only the fact that speaking about the output stage, I meant exactly and exclusively triode switching on 6P14P. It is in this inclusion that this lamp is able to touch the strings of the soul in a way that few others do.
Yes! This will result in a loss of power. But, perhaps, I should have said this before ... Hi -End is not for scoring discos. Moreover! In Hi-End, the quality of the device is usually inversely proportional to the power (read loudness) at which the amplifier fully reveals its capabilities.
In addition, I will hope that the very same 1.5 - 2 watts per channel that we can get with 6P14P in triode switching, in terms of subjective sound volume, will seem adequate to 10 watts per channel, obtained from a typical silicon-transistor wux.
So, just trust those thousands of people who have already walked this path before you and, believe me, were completely satisfied with the result. ;)
Moreover! I also have much more "serious" devices, which, of course, are objectively better than this creation. But this simple and seemingly completely uncomplicated machine has its own soul, gentle and kind ... It is capable of touching and warming human souls with its very warm voice. J (Evan pulled me away! .. Sorry again for the pretentious syllable.)
The only question of the circuitry of our wuxia, perhaps, was the question of "proper and healthy nutrition." And this, I must say, is a matter of paramount importance when it comes to sound! For the sound that we hear as a result is, in fact, nothing more than the power supply of your amplifier modulated by the input signal.
Hence the conclusion - the power supply of the tube amplifier should also be tube-powered! So this is a kenotron! And if we absolutely remain adherents of the classics, then the choke ...
And if everything is simple with the kenotron (by summing up the anode currents of all lamps, we get the total consumption, based on which the required kenotron is selected), then with the choke, a problem can really arise ...
However, I was lucky. In my bins I found a real choke from some old tube TV. But even if not, then the simplest and effective solution This problem would be buying at the nearest construction market for 120 wooden banal 18 Watt choke for old fluorescent lamps. Their inductance of 2 Henry (usually something like that ...) is quite enough for our purposes.
How long or short, but on the spaces of the Runet I managed to find two whole schemes that almost completely meet all the aspects sounded above. The first of them is built exactly on the idea that was described by me above. The second differs only in that it has a pair of output lamps in parallel at the output, but it has a beautifully painted power supply that fully meets all my requirements.
These diagrams are:
In fact, oddly enough, the essence of my article is not directly related to the amplifier circuit ... In any case, this is not the main thing for me in this case. The main thing is to talk about how to collect all this?
It is worth noting that the classical approach when building a tube amplifier, in contrast to transistor devices, usually assembled on printed circuit boards, is the so-called surface-mounted assembly.
Frankly, for me this has always been the most repulsive factor when it comes to assembling tube circuits. For me, who was used to making a separate printed circuit board even for a freestanding volume level changer, so that everything was correct and neat, the very thought of loosely dangling parts in the amplifier case, fastened together only by soldering and, sorry, dangling on snot, was frightening ... And , starting to build this machine, I had to overcome some internal barrier and practically on the go figure out how to fix everything so that in the future I would not worry about what, and not about…. is there something there at one fine moment ?. ..
Well, yes, everything is in order.
We take the body of our amplifier.
First, it is worth carefully separating those commutations that we will need later. With your permission, I will omit this stage, since it is specific and does not imply many solutions.
I'll just present the result as a given. In my case, it was the wiring of the input switch, ALPS for the volume control, and the input, output and power connectors themselves.
It is characteristic that at this stage we remove the upper and lower panels of the case. The lower one just interferes with us, and we will need the upper panel as the basis of our design.
Here's what we have at this stage:
Looks like I missed one important point... The fact is that before proceeding with the assembly of the amplifier, you must first select at least the basic elements of the future car. They are needed to determine the design of your device.
We are talking primarily about light bulbs, sockets for them, output and power transformers and chokes. About the very elements that are attached directly to the body.
And only having completely selected everything we need, we can arrange it the way you like, determine the places for these elements and mark the top panel.
Here's how I decided to arrange the elements of my amplifier:
I admit, I had the idea to plagiarize the layout of the elements from one of the most popular Audio Note amplifiers, but, overcoming this temptation, I decided to arrange the elements according to the classical scheme. The idea of this topology, in this case, is not fundamental. The fact itself is important as a stage. This must be done very carefully, thinking about how convenient the selected location will be for subsequent internal installation and about the mutual influence of the elements on each other.
It is, of course, about magnetic fields transformers and their direction.
I suppose there is no need to present a short school physics course .. Just remember this. ;)
First of all, we place the panels for our lamps and determine the size of the holes for them:
Here we are awaited by another ambush and a dumb question in our eyes: “And how can you drill such HOLES in a sheet of iron?!” ... In my case, it was exactly like that. And I could not find the answer to this question in the articles of "colleagues" who happily reported to me about how wonderful they assembled tube amplifiers with their own hands.
I had to go to the nearest construction market and retrain from an electronics engineer to a locksmith.
I took the data with an ordinary caliper-compass before going to the market. It turned out that the diameter of the holes for the sockets for the finger lamps is 18 mm, and the diameter of the hole for the socket for the octal lamp (kenotron) is 28 mm!
The study of the issue showed that for drilling holes with a diameter of 18 mm. you can find a classic drill, but for larger holes you will have to use a "crown" from "Bimetal".
This is how it looks:
Fortunately, I easily bought both that and another in the construction market at 350 wooden per unit of goods.
JIt is necessary to drill the holes very carefully, and it is necessary to drill on the side of the top panel, which will subsequently be turned into the body. I assert this based on own experience... Actually, an inquisitive eye will be able to see the consequences of my flaw in the photographs with which I accompany my story ...
Drill speed is the lowest. In this case, if possible, it is worth using the auxiliary handle of the drill in order to stabilize the beating of the crown as much as possible.
Naturally, the edges of the holes obtained must be processed to remove the burrs that will inevitably remain after drilling the holes.
It turns out something like this:
To be continued…
I was contacted by a person whom I once helped in a search for radio tubes. This time, he needed help in repairing the amplifier, which he assembled on these tubes: a strong hum appeared in one channel, which he could not overcome in any way.
Here I need to say a few words about the customer himself - this is a brutal uncle of a biker look, with a thick black beard and tattoos, while a kind-hearted man. His lesson to match his appearance is motorcycle repair. In electronics, he, in his own words, does not understand anything. Everyone would not "understand" that they can assemble their own tube amplifiers, but oh well)
I agreed to help him, and soon he brought me this miracle:
The body for the amplifier was welded from 2mm steel plate, which was then additionally aged and covered with copper. Fortunately, there are still photos of the workflow, so I will share them with the permission of the author:
All work was done by hand using a grinder, drill, files and, of course, a welding machine.
The design bizarrely combines modern elements and parts from Soviet radio engineering.
I really liked the textured finish of the case, and I even seriously thought about using something like that in my own projects.
In general, the amplifier was left to me with a request to have it repaired as soon as possible. I connected it to the speakers and made sure there was a strong hum in one channel. As you know, electronics is the science of contacts, so for sure either something has been sealed off somewhere, or, on the contrary, closed. This can be fixed pretty quickly, I thought naively.
When I first looked into the "basement", at first glance, everything looked good - at least for an amplifier made by an absolute beginner. The author simply took and put inside two boards of low-frequency amplifiers from Ural-112 radios.
But since the location of the lamps and transformers did not suit him, he evaporated them and diligently increased all the wiring connections.
Unfortunately, lamp technology does not tolerate such an installation: long wires, repeatedly intertwining and crossing each other, collect all imaginable noise and interference. In addition, the author used a monochrome MGTF wire, and it was almost impossible to figure out what was going where. And there was no point in leaving the motherboards: their only advantage, which is that they can be put "as is" and save time and effort, was lost, and only shortcomings remained.
For example, obsolete selenium rectifiers and huge resistors of the BC type, which were used only in the power circuit of the high-frequency radio unit (R5, R1 and R8), were in vain in the power section. But the resistive divider R3 – R4, which was supposed to supply a small positive voltage to the midpoint of the filament winding to reduce the noise level, was lost during the transfer.
It should be noted that this "not versed in electronics" person himself (albeit according to a ready-made scheme) unsoldered the display unit on lamps of the "magic eye" type, and even with a separate amplifier on a 6N2P lamp, which made it independent of the output level volume. True, in this case, huge 2-watt resistors were used (although 0.25-watt resistors would be enough for the eyes) - he put them according to the principle "a lot is not enough" so that there was definitely no overheating. Here is such an amazing combination of ingenuity, straight hands and, moreover, a complete lack of experience, leading to a little curious, but still impressive results.
Acting on a whim, the author made two channels of the amplifier completely mirrored - each with its own power transformer... This also turned out to be redundant, since it was no longer necessary to power the lamps responsible for radio reception. The second transformer only interfered, and even hummed strongly, because its plates loosened from time to time, and the design did not allow them to be reliably pulled together.
In general, I realized that there was no smell of quick repairs here, and the amplifier needed to be completely redone. The situation was complicated by the fact that in just a couple of days I had to fly away on vacation. As a result, I soldered the last details at night right in front of the customer, and the next morning, having slept a little, I was already rushing to the airport) But everything turned out as it should, and the customer was pleased with the pleasant sound of the amplifier and the absence of noise. And only later I realized that in my haste I completely forgot about photographing the work process.
There is, however, a frame in which I use a battery and a microammeter to determine the direction of the power transformer windings.
In fact, I had to work hard. After all, I, in fact, had to do double work: first disassemble the amplifier to zero, and then reassemble it, but already correctly. 95% of radio components in the process were replaced with modern ones. Only the electrolytes remained in the power supply - their polished cases were an element of the external design. They were well preserved, so that their total capacity was sufficient for the ac background not to be caught by the ear at a distance of 20 cm from the speaker.
When working, I followed the basic rules of hinged "lamp" mounting - minimizing (within reasonable limits) the length of the conductors, spacing the signal and supply lines in space, mutually perpendicular orientation of the power and output transformers, shielding, avoiding ground loops, etc.
On vacation, I had already begun to slowly forget about this project, when suddenly the customer sent me photographs showing something very interesting:
Taking advantage of the lack of an extra power transformer, he made a new two-tier casing for the amplifier.
Harsh tube amplifier tube amplifier, homemade products, modding, Alcatraz, equipment repair, long-post
It was no coincidence that the square holes appeared in it: it was decided to stylize the building as the building of the Alcatraz prison! Well, what is Alcatraz without a lighthouse?
As a result, it turned out like this:
The lighthouse is removable and magnetically attached. And the light in it not only lights up, but indicates whether the built-in Bluetooth module, which is one of the possible signal sources for the amplifier, is turned on.
This is how the ability to work with metal and the author's rich imagination, combined with my modest knowledge of lamp technology, led to the birth of a very unusual and functional device. I think the proper name for it would be "The Rock".
Briefly, mostly photo (re-uploaded in good quality). I must say right away that there was little experience and knowledge in radio engineering, I made a lot of mistakes. Not being a fanatical lover of warm tube sound, the assembly process itself was interesting to me.
The hardest part is finding the output transformers. I bought myself a ready-made TU-100M from the amplifier (for a long time I did not choose which ones I took). The frame was made of an aluminum profile and overdid it with a margin of safety.
The upper part of the case is made of 3mm steel. The holes for the transformers and lamps were laser cut. The bottom was also cut from 2mm steel with ventilation holes:
Front panel made of a piece of aluminum:
Scheme
The final amplifier is assembled according to a push-pull circuit on two G-807 tubes. The preamplifier contains two stages of amplification, assembled on a double triode 6N9C (foreign analogue 6SL7).Advantages of 6N9S:
1) The lamp was originally designed for sound applications;
2) Two triodes in a cylinder;
3) High linearity;
4) Wide distribution, low price.
Disadvantages of 6Н9С:
1) High internal resistance.
The pre-terminal amplifier (intermediate link between single-ended and push-pull amplifiers) is assembled according to a phase-inverted circuit on a 6N9C double triode, the main purpose is to form two mutually antiphase signals of equal amplitude from the input signal. In the TU-100M circuit, the lamp amplifies the input signal and the voltage amplified by it is fed to the lamp grid of the first arm of the push-pull amplifier.
Part of the output voltage of the first tube of the phase-inverting amplifier is fed to the input of the second tube of this amplifier. The voltage amplified by the second lamp of the phase-inverting amplifier is fed to the grid of the lamp of the second arm of the push-pull
amplifier. Thus, for the first arm of a push-pull amplifier, the signal passes through one tube, and for the second through two.
It would be better if the voltage applied to the input of the first arm was equal to the voltage applied to the input of the second arm. I made a slightly different circuit, with a modified phase-inverted stage.
Advantages:
1) Reduced requirements for filtering supply voltage;
2) Extremely low noise level;
3) Equal output voltages of the shoulders.
I found another option on the forums:
Sockets for 6Н9С lamps:
A DAC is assembled in the amplifier case with the ability to connect to a computer via USB:
Adjustment option:
Transformer screens, first sketches on paper:
Cut from 2mm steel: 
After filing and sanding:
Some more photos:
Cleaned up a bit:
Price: unreasonably expensive.
It's easier to buy ready-made for 4-5 thousand rubles. But if someone needs it, I can throw off the files for cutting and for printed circuit boards.
OWN LAMP AMPLIFIER
I was convinced of the superiority of the tube sound over the transistor one after the very first assembled and listened to the amplifier. Despite all the new microcircuits, transistors and other "stones", vacuum is still preferable for high-quality ULF. How not cool, but passing through the void sound signal has less distortion than passing through germanium and silicon. Moreover, the difference is especially noticeable during alternate listening to two amplifiers. In order not to buy expensive branded LUNCH, you can makeDIY tube amplifier.For those who decided to make sure of this for themselves, a simple classical scheme is proposedtwo-strokea tube amplifier with a power of approximately 20 watts per channel,from the site radiostation.ru.
For trance power, we take the good old TS180-2 from the TV. Output transformers are of type VT, but TANs can also be used.Using all the resources of military production and the invaluable help of Uncle Vadim in creatingtube amplifier, I managed to make such a device:
The basistube amplifier,is a duralumin plate 200x160 mm, 4 mm thick, on which parts and lamps are attached. Then the whole structure is painted white (black boxes are tired) and racks made of polished D95 duralumin are screwed in the corners. Power transformers and output transformers are placed in tin screens to reduce background and interference.
To save space, the power choke has been eliminated, and a simple P-filter is used instead, a 300 μF capacitor - a 15 W 100 Ohm resistor - a 300 μF capacitor. Backgroundtube amplifier in speakers,not bugged even in silence.
There is a lot of controversy about the advantages and disadvantages of tube circuits of low (audio) frequency amplifiers. There are, just the same, whole separate currents of tube sound, with their gurus and adepts. "Only lamps, no semiconductors", "hybrid", "single-ended", "fans of transformers (interstage)" and hybrids and subspecies. This is about homemade people who deserve respect in any case. There are also those for whom fooling their neighbor is a profession. It's really bad there. Of course, there are exceptions everywhere.
We will not touch on "theology" now, but let's see what we managed to do out of literally past rubbish.
Perhaps it's worth starting with the fact that we came to the Perm Territory to look for a place to live, mainly with the most necessary things and radio components were not among them. Fortunately, in the city there was a shop selling radio components, with a kind of assortment, however, and what was discovered was for happiness. The radio elements required for a tube amplifier are somewhat specific, not counting the radio tubes themselves. In a word, having thought about it, he advertised in a local newspaper about the purchase of a tube radio. They called a lot, gave a few just like that, with the condition of “pick-up-from-the-garage-by yourself”. There were as many as four pieces, then the relatives rebelled, and it was embarrassing to insist - then we temporarily lived with our parents, and I was making crafts with my grandmother in the private sector. Fortunately, the two radios turned out to have very close insides - a typical 6P14 bass amplifier circuit, and the same power supply. "Our Alena Igorevna has such a typical, typical appearance."
The first treacherous thought, which we hardly managed to strangle with a pillow, was simply to take and transfer these amplifier scarves into a separate box and ... and that's all. But in the first place, it would not be very aesthetically pleasing (But what about, almost the main highlight, the lamp outside? Show off of course, but beautiful after all). Yes, on printed circuit boards - well, no. In a word, it was decided to abandon the easy way, it is not the first time we have sniffed the rosin! So, everything is like people ... (humming under his breath) everything is like people’s. Yes, hmm, well, I laid out the lamps pulled from the radio on a rag on a workbench, sketched out a schematic, a power supply, so that all voltages were stabilized, everything was done. Output tubes 6P14, triode-pentode switching, output transformers, like TVZ 1-9, input stage 6N2P, but left the statement for later, after experiments.
We had never seen any decent lamp ceramic panels in the store, so we had to get out.
High sidewalls, only partly for simplicity. Largely for convenience - it does not badly protect fragile and breakable radio tubes, and given the upcoming construction site in the village, it is not at all clear where the apparatus will be carried. Again, it is very convenient to set up and remodel - turned it over and stood rooted to the spot, and the lamps do not need to be pulled out - solder, measure, turn on as much as you like.
Radiator on top for stabilizers, high-voltage and heating. Rectifiers for them in the basement of the chassis.
The body is disassembled, putty, sanding, a couple of layers of paint.
The assembly of the case is clean.
Mounted power-on toggle switches (heating and anode delay), power indicators on neon bulbs, lamp panels, output stage mode switches - triode-pentode, and switching on feedback.
Rectifiers are mounted in the basement, a fuse is on the back wall in the fittings, everything is connected, we carefully check the operation of the finished piece of the circuit directly from the network. Lamps stick out for entourage.
Everything works, hurray.
The queue for the power transformer. This one, from the same radio. The power should be enough. The casing was removed from the magnetic circuit, four studs made of long M6 bolts were soldered to it. To be installed sideways in such a recumbent position, so that all the wires are in the basement of the chassis. I boiled the coil in varnish so that it would not buzz.
High-voltage rectifiers have been installed and already tested, there are already four of them - for each cascade of two channels its own. Each diode is shunted with a film capacitor against switching interference.
Electrolytic capacitors here, including those from stabilizers. The stabilizers themselves will be on top of the radiator.
Power-on toggle switches and indicator neon lights are connected. Signal sockets and shielded cable to the first stage are visible.
Plank, no Picatinny - Mazay. Contact. Will be mounted on the screws of the transformer inside the case. The rectifier diodes of all lamps are conveniently soldered on it. Stabilizers, again outside on the common radiator.
Stabilizer + 5 volts. With USB socket. For the convenience of MP3 player operation. So as not to run looking for a charger or a computer. The usual 7805, in the classic inclusion - two electrolytic, two ceramic capacitors. Powered by a filament rectifier.
Oh, the transformer is in place. Charging too. Contact strips are pressed onto the fastening of the transformer, three diode bridges with electrolytes are soldered to them, charging for the MP3-shnik is turned on.
Shawl with stabilizers. High-voltage on discrete elements, three heat stabilizers in the middle - at 7806, plus, one or two (pick up) diodes to the common output.
On the other side of the board are power elements.
And inside out, to press them with their backs to the radiator. The board is also made in a somewhat original way - in the same way as with SMD elements, so that there are no tracks or pins on the radiator side. High voltage all the same.
By the way.
A lid is clear from above, so that your fingers do not get into high voltage. The radiator is standard, needle-shaped, the cover is made of 0.5mm galvanized steel roofing.
PSU tests. Connections between the rectifier and the stabilizer on a live thread.
The hardest part is sticking in place and installing. Radiator with stabilizers on the other side of the chassis. All wires collected in four bundles are threaded through the holes and led to the rectifier. With tweezers, with a bit of patience and care. Then the main fun begins - to look for a tester where which end of the wire and connect according to two circuits, so that nothing superfluous sticks out, so that "and don't be confused ... Kutuzov". Otherwise the fireworks might be a noble one, they swam, we know.
These are the amplification cascades themselves, their own, so to speak, person. Well, everything is like people. Automatic bias, interstage capacitors like PTFE, we are curious.
Output transformers.
It is clear from the radio receivers, they are boiled in wax with paraffin, the core is pulled hot in a vice through a strip of elastic so that the non-magnetic gap in each layer of iron is the same and minimal. When disassembling and assembling, we do not lose a strip of paper for a non-magnetic gap.
And in an impromptu casing from a condensed milk can.
Fill with wax, or neutral sealant, or epoxy, if not a pity.
Output transformers in place.
Listening in grandma's greenhouse, where there is more space. And what, I like it.
The acoustics were like this, the acoustic design was a "closed case", it plays well, but the sensitivity is not enough, you have to switch the output stage mainly with a pentode.
This is with a shroud on the radiator.
After working for some time, one of the output transformers burned out, and had to be redone for others.
