Here in Brazil there are a lot of this type of Blüthner and I work in some of them. The idea of the extra string was to do competition with Steinway on Germany. The way to tune this extra string is just in tone with the normal string behind it. This string makes the treble very nice and it is also used on Blüthner with 90 keys. ROGERIO CUNHA - IC MEMBER OF THE GUILD
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