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Just Keys

Just Keys is a medium upright or console piano that Cris Forster restrung three times and retuned four times in 1990. The graphic (left) shows the complete keyboard from the first key in the bass to the last key in the treble. In the detailed graphic, we see close-ups of the keyboard divided into two parts: the upper section spans the distance from the A1-key to the G47-key, and the lower section, from the G47-key to the C88-key.

Note that the B3-key identifies ratio 1/1, which is the fundamental frequency of the tuning. This key sounds G1 at 49.0 cps. Since the G11-key normally produces this frequency, observe that Cris eliminated most of the tones that comprise the first octave of the standard piano. Consequently, the A1-key now sounds frequency ratio 8/5, or a just major third, interval ratio 5/4, below 1/1, which is E flat at 39.2 cps; and the B flat 2-key now sounds frequency ratio 16/9, or a just major second, interval ratio 9/8, below 1/1, which is F at 43.6 cps.

The detailed graphic (click here to view detail) indicates a 10-tone octave, ratios 1/1–2/1, from the B3-key to the A13-key (two keys with two dark blue labels); a 17-tone octave, ratios 2/1–4/1, from the A13-key to the D30-key (two keys with two dark blue labels); and another 17-tone octave, ratios 4/1–8/1, from the D30-key to the G47-key (two keys with two dark blue labels). From here, three consecutive 12-tone octaves, ratios 8/1–16/1, ratios 16/1–32/1, and ratios 32/1–64/1 span the distance from the G47-key to the G83-key. These 12-tone scales resemble the tuning of a conventional piano. Short string lengths determined by the shape of the cast iron plate and the location of the bridge severely restricted alternate tuning possibilities in the upper treble range.

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