Hi
@Vegard Doszko, I have no doubt used the word 'bassetti' a bit clumsily. For me this term 'bassetti' was Giulietti's name for the free bass accordions that he developed - which may or may not have had a transformer. However, I see what you mean, if 'bassetti' is only to be used for non converter free bass systems - like MIII or other bass systems without stradella present, I will remember that for next time.

Incidentally, I also associate Zero Sette and Giulietti closely, so whenever I see the extra protruding rows of basses on either brand I think 'bassetti'. However, if it's a Hohner with a separate free bass, I never think 'bassetti', I think 'MIII' (3 manuals). I expect that illogical system of mine will be fairly unique in the accordion world.

While we are talking free bass terminology maybe I could check the term B griff, in relation to the bass of an accordion. Please correct me if I was wrong. In my understanding there is a B-griff bass which is a mirror of the treble B griff. However, there is also a Russian bass or Bayan system, which is an inverted B griff, with low notes near the floor, and so does not mirror the treble side. It is this inverted B griff that I believed was very common in Eastern Europe and particularly Russia. Is that right? If I have hammed that one up too, please break it to me gently guys

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Regarding system popularity, I think the most universal system (relatively speaking) is stradella. For me it is the foundation for most accordionists. Each freebass system has it's own strongholds. As there is no single generic chromatic bass system it is difficult to know which version is the most popular. I am guessing worldwide the inverted B griff (Russian) is the most common. Thoughts anyone?
I personally tend to take my inspiration from the main bass systems of Italy, and for me the important bass systems there are: stradella bass, Quint converter, and C-griff converter. I like the Italian accordion tradition so that's why I would seek these systems over others. - nothing to do with technical factors.
Stepping the bass seems like a good idea, or at least having a slightly greater gradient in the bass board angle to allow the thumb to be used more freely. The thumb is used quite a lot on quint converter, but only on the outermost row.