ARG 6S33S Triode Bridge Amplifier

Grzegorz "gsmok" Makarewicz (2011), This email address is being protected from spambots. You need JavaScript enabled to view it.

The amplifier belongs to a group of devices made in such a small number of copies that it is difficult to call its manufacturer a manufacturer. In this case, it is difficult to even talk about a manufacture. The amplifier has no markings and finding information about the person who built it caused me a lot of difficulty. It turns out that it is a product of a company (this is a bit of an exaggeration) called ARG. It is probably the work of one person, Mr. Yevgeny Kreminsky from Lviv.

I have not found any company website or official list of ARG products. The only source of information are the internet "notes" of a few users or friends of the amplifier designer. I decided to place the description of the amplifier in the Gallery primarily because of its rather unusual system configuration on the audio device market.

The ARG amplifier consists of two identical monoblocks. Photo 1 and Photo 2 show a general view of one of them.

Photo 1.

The design is impressive. The external dimensions and two output tubes (the famous military "devils" 6S33S) suggest at first glance that we are dealing with a typical push-pull system and lifting this 'monster' is not an easy matter. Imagine my surprise when I tried it. I prepared myself for a huge weight and lifting it with a large reserve of strength almost threw it into space. It turned out to be surprisingly light (as for a tube amplifier).

Photo 2.

The rear panel contains solid switches and speaker sockets, which could power many a high-power "welder". Unfortunately, the designer did not show off his sense of aesthetics. The veneer used here was probably supposed to resemble some precious stone, but ended up being an unintentional copy of kitchen linoleum from the 1970s.

Photo 3.

Another "bird's eye" view of the electron tube section. The sockets are well laid out, the power tubes have a lot of space around them, which is not without significance considering the fact that the "devil" tubes heat up to over 300 degrees.

Photo 4.

After removing the bottom cover, the inside of the amplifier is visible. The layout of the elements is quite good, but the assembly details and the quality of the printed circuit boards are impressive in a negative sense. However, I still haven't found an explanation for the low weight of the amplifier. So I decided to immediately remove the top cover and see why the speaker transformers are made of some strangely light material.

Photo 5.

And here's a view of the transformers - or rather, their absence. Under the solid cover I found the mains transformer (partially visible from the bottom of the amplifier) ​​and two small chokes.

Photo 6.

Please forgive me for taking the photos immediately after opening the casing, without dusting it. Unfortunately, my irresistible curiosity and desire to get to the inside as quickly as possible means that old dust appears on many of the photos I present in the Gallery. I hope this does not bother those interested in construction details.

Photo 7.

Here are the chokes in close-up. Ready-made elements in hermetic housings painted in a characteristic military green color were used.

Photo 8.

Photo 9.

Photo 10.

Compared to chokes, the mains transformer has impressive dimensions - as can be seen in the attached photos.

Photo 11.

It uses a wound core, and the general appearance of the transformer makes me think irresistibly of the mains transformers used in Soviet "Rubin" TVs. The "Rubin" models were wound with wire made of some aluminum alloy. I hope that copper wire was used here.

Photo 12.

It's time to take a closer look at the amplifier's circuit configuration. It turns out that this is not a typical push-pull circuit, but a bridge circuit often called a circlotron. The principle of operation is shown in the diagram below.

The circuit is so interesting that I decided to recreate the entire schematic diagram of the amplifier. Here it is (an enlarged version can be displayed in a separate window by clicking the mouse on the schematic diagram surface).

Please note that the amplifier schematic was reproduced from nature and is not authorized by the amplifier's Designer.

In keeping with the tradition of articles posted in the Gallery, it's time for a teardown session showing the details of the device's interior.

Photo 13.

This circuit board with its impressive array of capacitors is of course the power supply section for the output tubes.

Photo 14.

Here you can see it more clearly. Two solid circlotron power supplies.

Photo 15.

Here are the details of the perpetrator of the failure that resulted in the amplifier ending up in my hands.

Photo 16.

The following elements are placed on the board:

Here are some shots of the unfortunate mounting board.

Photo 17.

Photo 18.

The board was designed in a way that makes it impossible to perform measurements and service. To repair anything, you simply have to remove it. After removing the board, the housing becomes strangely empty.

Photo 19.

After dismantling the board, I had the opportunity to take a few photos of details that are normally hidden from prying eyes.

Photo 20.

Photo 21.

The inscriptions made with a marker on the power supply board and in a few other places are not mine. I found them after opening the case and left them for posterity.

Photo 22.

And here is the printed circuit board with components in all its glory. View from above. Next will be the view from the path side. Sensitive people are asked to skip the following photos.

Photo 23.

This is unfortunately how it looks from the bottom. It is difficult to say whether this was the condition of the original board installed in the device, or whether its appearance is due to the clumsy interference of someone who repaired the amplifier. I hope it was the latter cause.

Photo 24.

Repairing the system directly on the original board turned out to be unprofitable. I was forced to make a replacement board. For those interested, here are the details.

As a reminder, here's a view of the original board, from which I've already removed the choke...

Photo 25.

... and a view of the replacement board with new components, except for the choke, which I reinstalled from the original PCB.

Photo 26.

Now a direct comparison of the original and the copy. As you can see, on the new board I installed soldering pins that allow for connecting leads from the component side. This means that replacing components connected from the outside of the board does not require its removal.

Photo 27.

Photo 28.

New plate from the printing side. I made it by hand using the thermal transfer method.

Photo 29.

 This is what the inside of the amplifier looks like after installing the new printed circuit board.

Photo 30.

A careful observer will notice that some off-board components were also replaced - in particular the "audiophile" coupling capacitors, which were characterized by high leakage.

Photo 31.

Photo 32.

Photo 33.

Finally, a short summary. The ARG bridge amplifier is an interesting and rare design. The topology used compensates for certain shortcomings related to the quality of workmanship. Few audio enthusiasts have had the opportunity to listen to a tube "circlotron", and it sounds quite interesting despite the fact that the declared output power is significantly overstated. I encourage everyone to look around in the audiophile environment and take advantage of the opportunity to expand your listening experience with this type of device..

Prepared by: Grzegorz Makarewicz, www.mytriode.com, www.grzegorz-makarewicz.pl (formerly www.trioda.com)