I have nothing to add to the discussion about what constitutes a “real piano” because it’s been argued ad nauseam, both here and elsewhere.
But we do need a point of correction around the historical definition of a piano - as ultimately these forums may be used by students or those doing research, and factual errors may negatively inform their studies or research.
The idea that what makes a piano is merely its dynamic ability and keyboard layout is false. It is also not true that there was no other method or technology for a keyboard instrument to achieve variable dynamic control. The piano was NOT the first instrument with both a variable dynamic range and a 12-note-chromatic/“seven-plus-five” keyboard. That honor belongs to the clavichord.
Nearly 300 years before the historical piano was created, the clavichord existed, and had a variable dynamic range AND a 12-note chromatic keyboard in the seven-plus-five layout.
The definition of a piano was never MERELY its ability to variate between soft or loud and its keyboard layout, as the clavichord contained both those defining features 300 years before the piano ever existed.
So, if your definition of a piano is an instrument that can be soft or loud and has a traditional 12-note-chromatic/seven-plus-five keyboard layout, then that wouldn’t be accurate. And, concurrently, the idea that any instrument containing that keyboard layout and dynamic variability, is therefore, a piano…would also be inaccurate.
By that logic, digital pianos and keyboards could equally be called clavichords, since clavichords contained those same features long before the piano. Further, by that logic, a piano could be classified as a clavichord, since the clavichord came first by centuries. And that is not so. No more than a clarinet is an oboe, is a piano a clavichord, or vice versa, despite similarities.
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It’s also a bit of an error to assume that “pianoforte” was the original name of the instrument or even the true focus, per se. If we go back and look at the definition and description that the inventor of the piano, Bartolomeo Cristofori, gave, it becomes clear what he considered a piano to be: “Un Arpicembalo di Bartolomeo Cristofori di nuova inventione, che fa' il piano, e il forte, a due registri principali unisoni, con fondo di cipresso senza rosa”
So, the inventor of the piano, considered the instrument to be: “A harp-harpsichord which plays soft and loud, with two unison principal registers (two sets of unison pitch strings) and a bottom/foundation (soundboard) made of cypress without rose”.
To the inventor of the piano, it was not about merely the keyboard layout or the dynamic ability. It was the strings, the action (which was revolutionary), the body of the instrument, the soundboard as an important element of sonic projection, the mechanisms, etc. The inventor was very clear on what, in whole, defined a piano. Now, was the dynamic range important? Yes! It was a defining feature, as it was one of the first keyboard instruments that could compete with an orchestra and be featured in a large hall. But that alone was not the sole import. The tone/timbre of the instrument, the method of sound production, the construction of the instrument, all those things mattered.
As for why the name became shortened to fortepiano, then pianoforte, then piano, it was not because the only thing that mattered was the dynamic range, but because of linguistic issues and for promotional purposes. Cristofori’s inventions actually took off in Germany, when Gottfried Silbermann was introduced to them through Italian trade papers as “gravicembalo col piano e forte”. There’s an issue of translation from Italian to German. A choice was made to abandon the “gravicembalo” part altogether (which is how the design was introduced to Germany) and the original “arpicembalo” that Cristofori wanted, and to focus on forte and piano, terms already familiar in Germany, and terms that could highlight the loudness of the instrument compared to the harpsichord and clavichord.
But what a made piano was never merely its dynamic variability or its keyboard layout. So, to use that as the means of defining a “piano” would be inherently wrong, as a clavichord shares those characteristics, and possessed them first.
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Now, again, as I said, I’m not going to argue what a “real piano” is or isn’t. Everyone has their own opinions on the subject. But I do think it would be a mistake to define digital instruments as pianos SOLELY based on an inaccurate interpretation of what defined the original instrument.
And I think it’s important that we’re accurate with the historical facts of the instrument as this site may be used as a resource.