The pioneers of the first European quarter-tone piano were Russian-born composer Ivan Wyschnegradsky (1893–1979) and his Czech colleague Alois Hába (1893–1973). Wyschnegradsky emigrated to France where he created sketches for a quarter-tone piano keyboard. These sketches are on display in the Wyschnegradsky archives at the Paul Sacher Foundation in Basel, complete with precise dimensions. The quarter-tone keyboard consists of three keyboards: a middle keyboard with ordinary black and white keys, and an upper and a lower keyboard, both red in colour and tuned one quarter-tone higher than the ordinary keyboard. Wyschnegradsky took his innovation one step further: his sketches reveal designs for keyboards capable of producing even smaller intervals than a quarter tone, and he wrote musicological essays on the subject of “ultrachromaticism”. 

In the spring of 1924 the German piano company Grotrian-Steinweg in Berlin advertised a new instrument which they called ‘Vierteltonklavier’. That instrument resembled two adjoined grand pianos. According to the brochure this quarter-tone piano would have 176 keys, some white and black, and some red and brown in colour. The brochure also acknowledged the contribution of Alois Hába and Willi von Möllendorf. (Paul Sacher Foundation.) Unfortunately there is no evidence that their idea ever came to fruition although one octave prototype by Grotrian-Steinweg still exists. It has a unique layout with white, black and red-brown keys.

Finally, the August Förster piano company constructed a quarter-tone piano in cooperation with Hába and it was exhibited at the 1928 Autumn Fair in Leipzig. It has a similar kind of quarter-tone keyboard as seen in Wyschnegradsky’s sketches, although with traditional black and white keys[1]. A sample instrument was sent to Wyschnegradsky in Paris.

This Förster quarter-tone instrument has three keyboards: the upper and lower keyboards are tuned just like a traditional piano, with the octave divided into 12 pitches, and the middle keyboard is tuned like a normal piano but a quarter-tone higher. Alternating between the three keyboards it is possible to play all 24 quarter-tone steps within an octave, although, at the time it was developed, the two sets of 12 pitches or 12-tone scales were generally still used separately.

Today this instrument is often referred to as the `Hába-piano’. Förster constructed both upright and grand pianos according to this model, and some instruments are still in existence (Ex.4). However, although several composers of the time showed interest in producing works for the instrument, very few quarter-tone pianos were constructed by the piano manufacturer. Förster quarter-tone pianos can be viewed in music museums in Prague and in Cairo.

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In the United States, German-born composer-pianist Hans Barth (1897–1956) designed an instrument that he called a quarter-tone piano. It had 176 keys on two separate keyboards and was built by George Weitz in 1928. Barth composed chamber music and even a quarter-tone piano concerto for this instrument. His own performance of a composition entitled Shadows of a Cathedral shows how his hands alternate between the two keyboards. (USC.)

As microtones became a familiar part of many Western classical composers’ toolbox, the quarter-tone piano was utilised in diverse ways. In addition to Hába and Wyschnegradsky, American pianist-composer Mildred Couper (1887–1974) wrote music for two pianos tuned a quarter-tone apart in the 1920s[1]. The Mexican composer Julián Carillo (1875–1965) tuned pianos to different scales using a variety of regular intervals. In 1940 he even patented 15 different ‘metamorphoser’ pianos and co-operated with the Sauter piano company. Depending on the model, the pianos were tuned using scales divided into pitches ranging from whole tones to sixteenth-tones[2]. On the sixteenth-tone piano constructed by Sauter, the distance between the lowest and the highest notes is exactly one octave.