Tonal diversity is the concept that there are and should be many different “sounds” available in the piano world.
The basic premise lies in one of the fundamental concepts of music: that there is room for personal expression, in music styles, in individual interpretation and in the choice of sound one uses to convey these personal expressions.
The antithesis of tonal diversity is the idea that, despite the wonderful world of personal expression in music, there is only one piano sound that should be used.
It is the contradictory idea that somehow this one type of sound is perfectly suited to all the different styles, concepts and individuality that makes the musical world the fantastic wonderland that it is.
To support tonal diversity means that one supports personal, individual musical expression of emotions. Supporting and in fact demanding tonal diversity means that one actively seeks out avenues and tools for supporting ones own musical ideal.
The idea that there should be only one piano used for playing, for example, Mozart, Brahms, Schoenberg, Chick Corea and Vivaldi implies that there should only be one way of playing these masters of the keyboard medium. And yet, generations of serious students of music have been encouraged to find their own path, to explore their own emotions and develop their own unique”voice” when approaching the music of the masters.
These 2 concepts, that there should be individualism in musical interpretation but singularity of tools used to express that individualism cannot be reconciled.
The latter must be seen as marketing.
None of the makers represented here argue that their concept of tone should be the only one available. None of these makers will present their products as the only true representation of piano tone. Each of these makers exist BECAUSE of the concept of tonal diversity and each of them completely embrace the idea.