Bohlen-Pierce minus 1
This post refers to my song “Bohl-en Roll”, a piece based on a dodecatonic scale which repeats every 1901.955 cents (3/1 ratio).
In order to fit a BP scale into an octave of a standard keyboard I chose to eliminate one of the usual 13 steps of it and I based this decision on the Bohlen-Pierce Scale Research Paper by Elaine Walker (the pattern of my scale is 0, 1, 2, 3, 4, 6, 7, 8, 9, 10, 11, 12, 13).
This arrangement makes it possible to play all but one of the “diatonic” modes presented on the above mentioned paper. The missing step is ratio 75/49 (736.93 cents) used only on the “Delta” mode. On my ET version the missing step is 731.521 cents.
The top picture shows my pitch assignment arrangement for the octave C3 - C4. An octave span on a regular keyboard equals an octave plus a fifth (a twelfth) pitch-wise. The regular BP pitch assignment, on a standard keyboard, would be the one showed on the bottom picture. A twelfth would span 13 keys from C3 to C#4 making everything, in my opinion, much more difficult. My reasoning is that in 12tET tonal music very seldom all twelve available pitches are used, so that should “equally” apply to BP music.