On Fri, Feb 27, 2015 at 09:24:50AM -0500, tom haddington wrote: Saluton The bad news is that Bristol uses only 440 Hz, 69 and 0 for reference frequency, keynum and scale degree-index respectively. For example, with the pitch values of a just intonation: 16/15 9/8 6/5 5/4 4/3 7/5 3/2 8/5 5/3 9/5 15/8 2/1 the notes are: A (1) A# (16/15) B (9/8) C (6/5) C# (5/4) D (4/3) D# (7/5) E (3/2) F (8/5) F# (5/3) G (9/5) G# (15/8) The middle C (keynum 60) is 440 x 3/5 = 264 Hz and probably it is not a big problem for you. But what is the frequency related to the keynum 60 when the number of the notes of a scale is not 12, and/or the interval between keynum 69 and keynum 72 is not a 3min ? I think it is your problem with Bristol. For example, the pitch values of a golden pentatonic are 5/4 21/16 3/2 13/8 2/1 and the keymap starting from keynum 60 (middle C) is 60 5/16 61 21/64 62 3/8 63 13/32 64 1/2 65 5/8 66 21/32 67 3/4 68 13/16 69 1 70 5/4 71 21/16 72 3/2 73 13/8 74 2 If we press the key of the middle C, we hear the frequency 440 * 5/16 = 137.5 Hz and obviously it is not a middle C. Without the possibility to define a keymap, the trick is to add other notes to get a (not necessarily chromatic) scale with 12 notes. One of the possible scales from the previous pentatonic is 16/15 9/8 6/5 5/4 21/16 7/5 3/2 13/8 5/3 9/5 15/8 2/1 But what if we want play the ji-scale of the first example starting from another note ? The trick is to write a scl file with the intervals of a modal chromatic scale. If we want a ji in C, we write a modal chromatic scale in A by translating the pitch values: 9/5 / 5/3 = 27/25 15/8 / 5/3 = 9/8 2/1 / 5/3 = 6/5 32/15 / 5/3 = 32/25 [...] and the result is 27/25 9/8 6/5 32/25 27/20 36/25 3/2 8/5 42/25 9/5 48/25 2/1 In this example, the interval of a minor third is always 6/5, therefore the frequency related to the middle C remains 264 Hz. Now we can play the follow notes with Bristol: C (1) C# (16/15) D (9/8) D# (6/5) E (5/4) F (4/3) F# (7/5) G (3/2) G# (8/5) A (5/3) A# (9/5) B (15/8) Just my 1200 cents :-) Tito P.S. I have written some utilities to create and manage musical tunings: http://incudine.sourceforge.net/tutorial_tuning.html