Wzmacniacz Xindak MT-3

Details: Written by: Grzegorz Makarewicz; Published: 22 June 2025; Hits: 72

Grzegorz 'gsmok' Makarewicz

A tube amplifier from the so-called mid-range. A traditional system solution with an unconventional, rarely used option of switching between triode and pentode operating modes. I was encouraged to post a short description and not so short set of photos by the information appearing in many places that this is an amplifier with automatic polarization, which does not require adjustment of the quiescent current of the output tubes. Well, this is not true and I warn the users of this amplifier against a careless approach to this important issue.

Breaking with the convention of the order in which device photographs are posted in this section, in which the first photo shows a general view of the device and "disassembled" photos appear later, this time the first photo I show is a photo of the amplifier warming up during the quiescent current adjustment procedure after replacing the output tubes.

While searching for information about the XINDAK MT-3 amplifier, I was surprised to find that despite the large number of sales offers and positive opinions, there is virtually no detailed information regarding its SAFE operation. Replacing tubes in a tube amplifier is not the same as changing a toothbrush. It must be approached in a thoughtful and, above all, safe manner. And here I return to the introduction. In one of the audiophile magazines (fortunately not Polish), I found an opinion expressed by an "expert" on the subject that due to the automatic polarization of the output tubes, this amplifier is a particularly good proposition for those who like to experiment with tubes. They can replace them at will without the need for any adjustments. I have little hair left on my head, but what little remained stood at attention when I read about it. As an example of the dangers associated with replacing tubes, let me use the fact that after replacing tubes in the amplifier that I am presenting here without adjustments, the measured currents took values from 35mA to 80mA for individual tubes.

I would like to congratulate our national discussion groups. I found threads in which the discussants are aware that the amplifier requires regulation of quiescent currents. Unfortunately, that's where it ends. Most of the statements come down to advice that these currents should be regulated by ear. Tubes are supposed to serve the owner, not themselves. Dear Audiophiles, who are pushing this type of opinion - "by ear" - the audiophile died in hospital (by the way, he was a friend of the guy who died by eye). If the amplifier does not work for you with correctly set quiescent currents, change the amplifier to another one that will work for you and do not cry that the tubes for which you set operating points "by ear", within which you exceed their permissible power emission values by 50%, work only for a dozen or so hours. Well, but enough of these complaints ;-).

Now I'm going back to the beginning, or photos from general view to details. Feast your eyes on beautiful views, because there's a lot to look at. The amplifier is really well made, has a well-thought-out design. I found only one "shortcoming" - too short wires connecting the main board to the transformers, which makes servicing a bit more difficult - but that's really a minor thing.

There are several versions of this amplifier model on the market, differing in housing (there is a version with wooden elements - really nice) and equipment (gain control and input selector). The one presented here is the "poorest" version. The technical specification is common to all versions. Here it is (manufacturer's data):

Technical specification