I’m going to be posting today a cover of the song Saint Joe on the School Bus by Marcy Playground.
The song’s verses have a simple F#m A E progression. But when playing it in 15 you have to decide which F# to use (if you visualize it like me and take the open E as a reference point). So in this tuning there are 3 types of 2nd, and essentially two types of major 2nd, one at 160¢ and one at 240¢, conveniently located exactly opposite the 200¢ of 12edo.
And actually, in the case of this song, the small (140¢) major second between the E and the F# is the choice I use because it shares the C# chord tone with the A.
What is more interesting also is that in just intonation, the big and small major seconds are 9/8 and 10/9, and there are combined to make the just major 3rd of 5/4 – two unequal step sizes. This is in fact a property of 15edo: that you need a 240¢ and a 160¢ to get your 400¢ major 3rd. In this case, it is quite exaggerated from the 9/8 and the 10/9 (~204¢ and 182¢ respectively).
In 15edo as in the just system, the bigger whole tone (240¢ and 9/8 in these cases) is the difference between the unison and the major 2nd, and the distance between the fourth and the fifth, and the distance between the major sixth and major 7th. The small tone (160¢ and 10:9 in these cases) is the distance between the major 2nd and major 3rd, and the fifth and the major 6th.
Here is the song. For more please see the Patreon page