During my radio amateur career, I have assembled and tested more than a dozen different amplifiers on tubes - both push-pull and single-ended, including several with parallel connection. Most often, the good old and were used. However, the Internet has repeatedly flashed circuits with lowercase pentodes at the output - 6p45s, 6p44s and 6p41s. I decided to stop at the latter, since despite the lower power than that of the 6p45, it does not have an uncomfortable and dangerous pimp on top, where the anode wire with high voltage is connected.Controversial reviews on audiophile forums fueled interest even more - from praise to complete denial of its sound parameters. As you know, it is better to assemble it yourself, and then make the final conclusion. I took as a basis schematic diagram S. Sergeev's single-ended amplifier, only slightly changed the ratings of the straps and the offset of the output stage.

The driver has the usual 6p14p in the output - here its role is secondary, preliminary amplification. In the output stage - 6p41s with automatic bias, which has proven itself well for its simplicity and stability of the lamp operation parameters. The only difficulty - a powerful resistor, was solved in an elementary way. Since the search for boxes with 10-watt green ceramic resistors did not give any results (there is everything except the required 450-680 Ohm), I had to solder a garland of three MLT-2 on a small scarf, 180x3 = 560 Ohm.

The cathode resistor of the second channel is also assembled on it. Since the estimated power is 2 watts, these 6 are quite enough. All the same, I would have to think about how to fix 2 powerful tubular resistors.

The power supply to the ULF comes from the mains transformer, rectifier and choke. Transformer TSH-170 - from a tube TV, you can also put TS-160, TS-180 here. In general, anyone capable of providing 250-300 V 0.3 A of anode voltage and 6.3 V 3 A of filament voltage. Rectifier diodes - IN4007, choke - DR-0.1. It has 1000 turns of 0.25 mm wire (this is if you do not find a ready-made one and will wind it yourself or take a network transformer to replace it).

Despite the significant voltage and current in the output stage - about 0.06 A, I ventured to put relatively weak TVZ-1, more appropriate in 6p14p amplifiers. As it turned out later, I did the right thing :)

The case for our single-ended ULF would not hurt to take a metal one, as I always did before, but I decided to take a chance on this too, using an unnecessary Chinese front speaker from a 6-channel computer amplifier. This number also went off with a bang :)

Gutted the speaker system, design the future location of radioelements and cut out the necessary windows.

The lamps should naturally be on top, we install them on a metal base - a sheet of two-millimeter aluminum, with cut-out round windows for the panels.

Then this sheet is glued with self-adhesive "metallic" color to match the main body. After gluing, the lamp holes are gently released with a blade.

The lower part of the case is also reinforced with metal so that the heavy mains transformer does not fall out. It was planned to install an electronic power filter on it, but in the end it was abandoned. The voltage at the output of the PSU is already not enough (only 260 V), therefore, losing 20 V at the EF is a waste.

At the back we cut out a rectangular window for a textolite panel of sockets and connectors - network, audio input and audio output to speakers.

We also glue this panel with self-adhesive.

Then we insert all the contact elements and fasten it with screws to the previously cut AC window.

Large electrolytic capacitors are mounted on a single aluminum base. There are 4 of these overall electrolytes - three for the PSU filter and oneat 300 uF 63 V, installed in the cathode 6p41s.

The material of the case - chipboard, turned out to be very convenient in processing, and the electromagnetic interference from the devices, which I feared so much, was absolutely inaudible. But that's about this article - assembling, configuring and testing the circuit.

This is a development somewhere in the late 80s. During this time, it has proved to be worthy and versatile: it is suitable both for lovers of high-quality sound (composed for myself) and for musicians who need power.

A short lyrical introduction. At one time, the amplifier was very popular, published in the magazine "Radio" 72g. I also repeated this scheme. Its disadvantages are known to many who repeated it: low linearity, weak stability on the HF, insufficient high frequency stability (from which a correcting air conditioner was introduced into the circuit), a narrow frequency range, and something else that I don’t remember now. And most importantly, the sound left much to be desired.

I could not stand this at home: my ears were not official :) The first thing I started with modernization was to replace the weekend trance. The changes made to the output trance suggested themselves - to tighten the connection of the feedback windings (ultralinear) with the rest of the windings, than to reduce Kg at higher frequencies, and to improve the frequency and phase characteristics of the output stage. In the version that I used in the new design, it was possible to expand the frequency range, increase the RF stability, and lower the output impedance. The sound has improved markedly, but now all the circuitry (a clone of the so-called "Williamson's circuit") began to seem pulled by the ears in Hi-Fi - it was made somehow "head-on", the weak link remained weak stability with OOS at infra-low frequencies, increased nonlinear and frequency distortion (especially at HF).

Further improvement resulted in a complete rejection of this scheme. Many different circuit solutions have been tried. Attempts to find the best option led to the solution that I propose. At the input, I used a cascode VN with high linearity, then - a phase-inverted cascade with a split load, which has the greatest linearity. In doing so, I linked them directly to reduce phase shifts along the signal path. At the output, however, the familiar ultra-linear output stage remained with minor changes (for the purpose of ease of adjustment and increased stability), and, as already mentioned, with an improved output trance. In the diagram, I conditionally divided the preliminary stages, a bunch of triodes in which, in fact, are my know-how;), and the output stage, instead of which you can connect any suitable one. With a properly manufactured and adjusted amplifier, the maximum amplitudes on the control grids of the output lamps should be at least 80V at a load of 47k. And this made it possible to completely swing the 6P45S. And what is important, for all its merits, the scheme turned out to be even easier than that from which I had to leave.

The result is an amplifier with a sound that (with proper measures) may well claim to be hi-end;) The amplifier is absolutely stable, so it can be used both with deep OOS, and without it at all - the linearity of all stages provides low distortion and with open loop OOS.

From two 6P3S, I managed to get> 150 watts, from two 6P45S -> 220;), and in the version with grid currents (especially for musicians) - 400 watts of peak power! But that scheme is already noticeably different from the one given.

I cannot give detailed parameters of the amplifier now - I haven't measured it for a long time. For those who need sound and not parameters, I have given enough information for repetition, and if I really need it, I can (albeit very scrap) re-measure. For a magazine I would probably measure it. And here it will do anyway: o)

As for the setup, it is simple:

1. to collect standard scheme parameter measurements;
2. disable OOS;
3. turn on the gain and warm up the cathodes;
4. resistors R10 and R11 set the quiescent currents out. lamps 30 ... 60mA (0.06 ... 0.12V at the cathodes), but always the same;
5. without giving a signal to the input, set the regulator R2 to 105V on the cathode of the phase inverter;
6. apply a signal to the input until a voltage of 15 volts is obtained at the load (for a 6-ohm varant);
7. resistor R9 sets the minimum of the 2nd harmonic at the output;
8. restore OOS (optional).

Point 7 can be skipped if you replace R8 and R9 with one, with a resistance of 12k (this may not even affect the quality in any way, especially with OOS).

To power the amplifier, additional voltages were needed: 410V (10mA / channel) and stabilized 68V (b / t). The diagram shows the idin of the options for obtaining them from the available ones. Here you can do it in different ways. For example, I have a source of stubs. + 220V to power the preamplifier, so I got +68 with a divider.

At one time, the scheme was shrouded in commercial secrets :). Now please - let anyone who wants to try. I repeat that the UN-FI link is universal, and can be used to drive various output PP stages (triode, pentode, class A, AB). For each specific case, you may have to recalculate some elements, which is very easy. In this I can help those in need.

P.S: The Surf amplifiers lend themselves well to such alteration - the quality is noticeably improved.

List of radioelements

Classic amplifiers of the ZEN class seem to have been in the past for a long time, but radio amateurs have recently often reproduced such circuits. This class amplifier has excellent frequency-dynamic performance. Mark Houston's famous amplifier gives great sound, although in some of his videos this scheme was repeatedly recommended not to be repeated.

But with the use of good modern components, the picture immediately improves. It turns out single-ended amplifier class A, in which the amplifying element is a sufficiently powerful field-effect transistor. The power of the amplifier reaches up to 5 watts, think this is not enough? on the contrary, for class A amplifiers, this power is very high. Those who want to dispel doubts can assemble the circuit on their own and make sure.

The only drawback of the circuit, like any class A amplifier, is its low efficiency, the value of which is a maximum of 15-20%. Consequently, the remainder of the original energy is spent on heating the transistor and the limiting resistor.

This circuit is rightly called an amplifier without parts, since it element base contains only a few components, although you will have to spend a lot of time in electronics stores to get them. The basics of the work are not hard to understand.

The most "heated" element in the circuit is a resistor located on the positive rail, which dissipates 60-65% of the total power, releasing heat, so it should be taken with a high power, about 40 watts. A polypropylene capacitor and a film capacitor are used in parallel with the 10 μF output electrolyte.

The amplifier is tuned with a 100 kΩ variable resistor, which sets the bias voltage at the gate of the field-effect transistor. It is recommended to take it multi-turn, since even a slight deviation from the required resistance can lead to abnormal operation of the power amplifier as a whole.

The 15 ohm resistor value may deviate by 5 ohms up or down, but this is not critical. Its effective power should be at least 40 watts, because the main part of the initial power (about 65%) is dissipated on this resistor in the form of unnecessary heat, and the rest on the transistor. All other components in the circuit do not overheat.

The power element, which is also an amplifying element, is a field-effect transistor. It can be taken as low-voltage and high-voltage. If you use low-voltage field-effect transistors, then transistors of the IRFZ20, IRFZ40, IRFZ44, IRFZ46, etc. series will do. And if you use high-voltage, which is more preferable, then I advise you to take at least 200-250 Volts.

In my version, a field-effect transistor of the IRF630 series is used, you can also replace it with the IRF640, which also proved to be excellent. The capacity of the input capacitor is not important, it can deviate in one direction or another by 50%. You can use film-type capacitors with a capacitance of 0.1 μF to 2 μF.

If you put a 5 μF film capacitor instead of 10 μF at the output, the quality of the amplifier does not suffer from this.

It is advisable to select the output electrolyte for a voltage of 25 volts, but in principle it is suitable for 16 V. The voltage at the plus of this capacitor should be 12 volts relative to ground.

The field switch must be installed on the heat sink, perhaps the circuit will require forced airflow, since the resistor heats up very much (you can make a cup of coffee on it without jokes).

I highly discourage powering such an amplifier from unstabilized power supplies.

The Musical Paradise MP-301 MK3 tube amplifier was developed in Canada by Harry Huang and produced in China by a small factory.

The first version - Musical Paradise MP-301, was released in 2008.

Actually, in Canada, this amplifier and the largest number fans. Read them, and there are many interesting things.

Pay attention to the photo from the forum - a man relaxingly indulging along with his dogs to the sounds of this amplifier.


This is exactly the effect of the tube sound on the body of all mammals. So do not be surprised if after turning on the amplifier you want to lie down, close your eyes, relax and get all thoughts out of your head. (Remember to leave the door open for your dogs, cats, wives and children to come along with you.)

"Lamp sound", by the way, heals well against depression, blues, melancholy and headaches.

The third version of the amplifier is much different from the second, and the first is generally not similar to the third, neither in design nor in circuitry.

This is the first version:




This is the second version:






This is the third:


Everything is much better inside, and in a completely different way. Pay attention to high-quality components: "military" resistors Vishay Dale, capacitors RIFA 450, Rubycon, Philips BC and Nichicon:


The transformers are wound with oxygen-free copper wire, the cores are Japanese transformer iron Z11 and M6. The volume control is made using ALPS technology.

The main feature of this amplifier is that it is universal - its output tubes can be selected at will (and then changed independently): 350B


350C, KT66, KT77, KT88, 6L6, EL34, 5881, Russian 6P3S and 6P3S-E.

You can put lamps G807 (Russian G807) through a special adapter:



Input lamps can be either 6J8P, 6SJ7, 6SH7 (or Russian "glass" 6Ж8П and "metal" 6Ж8).

The amplifier has a microcircuit for automatic bias control, so it doesn't matter what degree of "kill" your lamps will be, it will automatically set the optimal operating mode for them. Despite this, the manufacturer still recommends installing matched pairs of lamps in the device.

When ordering an amplifier, you will be given the opportunity to choose the type of lamps free of charge. I ordered a 6L6GC weekend (the included ones shine like a Christmas tree):






and input 6J8P:


All of them were produced by the Chinese company Shuguang.

You will have to pay extra for branded ones when ordering. All lamps came new, in packaging, matched in pairs according to parameters.

I compared Chinese Shuguang 6L6GC bulbs with used bulbs bought on Ebay: American Sylvania 6L6GB, Japanese Toshiba 6L6GC. I also listened to the 6P3S from the seventies, and the new 6P3S-E from the eighties, and did not notice any particular difference between them, although the Japanese lamps looked more neatly made.

Canadians also noticed that b O Replacing the input tubes (RCA with a metal bulb) gives a greater effect than the output tubes. But nevertheless, the Czech JJ (Tesla) EL34 or KT88, or RTF EL34 are recommended for the exit.

Now all the Chinese lamps have been replaced. At the entrance put "mixed" used Sylvania 5SJ7GT:


Fine.

I ordered old metal radio tubes 6Ж8 for fun:


New ones came, each in a cardboard box, produced by my native Novosibirsk, produced in 1968. They are at my entrance and will remain.

P.S. No, they won't. The sound of the new 6Ж8 is worse than the used Sylvania 5SJ7GT.

At the exit are now (bought on):

I gave 1600 rubles for two lamps and delivery (700 + 700 + 200) (to Novosibirsk from St. Petersburg).

I put it on the way out in the same way (bought on):

I gave 1200 rubles for two lamps and delivery (500 + 500 + 200).

(It was possible to order and:

although they are much more expensive - 2000 rubles a piece. In addition, they look somewhat vulgar because of the "golden" paint).

The sound of the Musical Paradise MP-301 MK3 amplifier is excellent.

In the audio salon of my city, I compared it with the VINCENT SV-237 hybrid:


for a crazy 162 thousand rubles, and (in my opinion) mine sounded better.

Earlier, for a long time, I had already heard tube amplifiers, the first I had was the legendary Priboi 50 UM 204S in the nineties. Even then I remade it (although I had never held a soldering iron before) on the recommendation in the article by A.M. Likhnitsky in the magazine Audio Shop, No. 1, 1996. It sounded really good.

Then he gave it to specialists to remake it into a one-cycle on 6C4C lamps. After the rework, only the output transformers, top cover, chassis, and bottom cover remain from the original Surf.

This amp sounded good, but there weren't many highs and lows, and it played poorly on Black metal, which I mostly listen to. So I sold it in the 2000s.

After studying the forums, I came to the conclusion that for metal I need an amplifier based on 6L6 or 6P3S tubes.

And finally, after ten years, I bought myself just such an amplifier.

Having dragged, not particularly heavy, this amplifier to the audio salon, and having listened to different acoustics on it, I discovered that expensive Bowers & Wilkins 685 bookshelf speakers are better than cheap floor standing speakers. I had to crush a toad.

The amplifier has a headphone output (2 watts) on the front panel, the quality of which was a pleasant surprise for me. The sound through it is simply amazing, it is powerful, energetic, in some ways even epic. And this is clearly audible even on headphones of not the highest price category.

So if everyone in your house is asleep and you can't stop listening to music, plug in headphones to the MP-301 MK3.

This is important: if your source has a headphone output, do not use it, but connect headphones through this amplifier. It will enhance the sound of any recording.

Pros and cons of buying:

There are a lot of pluses.

Minuses:
1) Power cord with Canadian 3-pin plug.

2) Fingerprints and dust are easily visible on the high-gloss piano lacquer finish.

3) The amplifier heats up decently during operation, especially the output lamps outside and the choke in the power supply inside. The ventilation holes are located only at the bottom.

4) The headphone output may have a little background (with 6L6 bulbs it will be minimal).

5) Output connectors for acoustics are located very close to each other, which makes it impossible to use “spade” connectors to connect speakers due to the threat of short circuit:


6) Harry Juan does not give anyone the circuit of this amplifier, so you will do its upgrade (replacing resistors and capacitors, for example) at your own risk.

This review will be supplemented, write your comments.