Illustrated Catalogue of Steinway and Sons' Pianos. E-book. Formato PDF Steinway And Sons   -  Forgotten Books, 2017  - 

Gentlemen: I can only congratulate you on the great improvement you have achieved by the introduction of your Duplex Scale into your piano-fortes. I have repeatedly and carefully studied the effects of the Duplex Scale just applied to my Steinway Grand Piano. And find the improvement most surprising and favorable, especially in the upper notes, for Splendid as my Grand Piano was before, the Duplex Scale has rendered its tone even more liquid, singing, and harmonious. I deem this improvement very happy in its results and being based upon scientific principles, capable of still greater development. Yours, very truly, H. Helmholtz.