Manual on the right (numbers inserted):

The keyboard block of the previous instrument with the keys 2/0 and 3/0 added by H. Band has been extended by a key 14 with the tones d#2/g2. However, these are only repeat (duplicated) tones, as they are already present on this side. They increase the number of designated tones by 2, but the players do not have a larger stock of different tones at their disposal.

The number of tones indicated for the previous instrument has increased by 4 to 64, but only two of these are new on the left page, as shown below. Here on the right side the two additional tones (14) are only repeat tones.

Manual left (numbers inserted): G - a1

A key 14 with the tones f/f# is also added to the left Manual, which, however, are not repeat tones but are new. But they can only be played by changing the direction of bellows.

To circumvent this restriction on playing, on the following models a key 2/0 (f#/B) with a second f# for the other bellows direction also appears immediately. Since also the B is only a repeat tone, this 2/0 key does not extend the tone but makes it more available.

According to this example the development of the instruments took place step by step with new and repeat tones.

The bandonion presented here was tuned two semitones lower. On the key of note 'C' is therefore 'Bb'. All keys which otherwise call up the C major scale will here play Bb major. With the more comfortable C major fingering the Bb major can be played, which is otherwise more difficult to finger on normally tuned instruments.

This is advantageous when playing with wind players, as their often preferred key is 'Bb' because it is easy to play on many wind instruments. Bandonions tuned differently in 'Bb' were therefore often played together with wind instruments - for example on a birthday...

Manual right: e1 - cis3

Another reason for a retuning could also be the pure tuning, which was still partly used until the 20th century. With this tuning one octave was not divided into 12 equal intervals (equal temperament), but in pure-sounding tone intervals formed the standard. This however results in more and less harmonic sounding keys. The preferred purely tuned keys were placed on comfortable fingerings. An instrument played notes on the C major keys would then sound in, for example, E flat major. In this case, the original notes must always be lowered by 3 semitones. (transcribed or played).

The spread of the bandonion in Germany was closely linked with the development of the association system. The first club was founded in 1874 as the Harmonika-Klub in Chemnitz. The second club followed 1875 in Hamburg, whose fiftieth anniversary is shown in the picture above from 1925. By the turn of the century, mainly from 1890 onwards, 75 clubs had been formed, Just under half of these were in the cities of Chemnitz (15) and Leipzig (18). Depending on the region, these were initially either concertina or bandonion clubs. Only from around 1900 were there also mixed ensembles. (Graf, p. 161f)

There was a founding high during the Weimar Republic. Later on, 686 clubs and orchestras with an average of just under 30 members were forcibly integrated into the the Reichsmusikkammer (Empire Chamber of Music), installed by the Nazis in 1938. The number of organised players was over 10,000. The bandonion movement, consisting of these associations was mainly concentrated in the cities, with a focus on Saxony. In the centres of Chemnitz, Leipzig and Halle there were several per district. In 1937, 44 clubs were counted in Leipzig alone. Without exception male societies, these consisted mainly of workers and craftsmen, as well as salaried employees and smaller self-employed people. (Graf, p. 161f)