[Quetscher]

Hi Ofir,

thanks a lot for your comment, I’m really glad I could make clear my intentions concerning the possibilities of varying the sound of one and the same instrument.
A Vibrandoneon is built a little like the keyboard side of a small accordion – you have two sets of reeds on a reed block that is (unfortunately!) not removable (this would make tuning so easy!) but glued into the instrument thus dividing the air chamber in two parts. Either you can play each set of reeds separately or both sets together – so you have 3 sound options: middle octave (8’ register), high octave (4’ register) or combined 8’+4’ which of course sounds in octaves.
Just have a look on this site:

http://www.akkordeon-maurer.de/documents/d/Accordina_Blasakkordeon_Clavietta_Claviola_Melodica_Vibrandoneon.htm

There you can find a photo of the inside of the Vibrandoneon plus two sound examples, the first one (“Barchino”) played with 8’, then 8’+4’.
In my opinion it’s not necessary to have two different sets of reeds, it leads away from the idea of keeping things simple – which is an idea that I strongly associate with the melodica. But on the other hand sometimes it sounds really great, especially for tango music!