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Magical mystery meanpop wreckage

🔗Gene Ward Smith <gwsmith@svpal.org>

12/23/2003 2:21:32 AM

If we take the duodene, which is the genus 3^i 5^j where i runs from
-1 to 2 and j from -1 to 1, we get something which mapped by meantone
gives us i+4j, which runs from -1-4=-5 to 2+4=6, the meantone 12-note
MOS. If we take instead the major/minor thirds parallogram, which is
the same as the duodene but with 5/3 in place of 3, we do not get a
MOS. Instead, we get 3i+4j, which gives us the values
-7,-4,-3,-1,0,1,2,3,4,6,7,10. In septimal meantone, this gives us the
magic chords of the augmented triad, based on (5/4)^2(9/7)/2 =225/224,
and the diminished seventh, based on (6/5)^3(7/6)/2 = 126/125. We
don't need 81/80 to find this temperament; the existence of the above
two magic chords determines it. Beyond the 7-limit, septimal meantone
divides into what I call "meantone" and "meanpop", depending on how
11 maps, with the dividing line being 31-et for which the two are the
same. Meanpop territory is where the fifths are just a tad flatter,
as for example 50-et or Wilson meantone.

Further magic awaits us in meanpop land. We have (9/7)/(6/5)/(20/13) =
351/350 (the ratwolf triad) and (5/4)(7/6)/(16/11) = 385/384 (no name
known to me.) If we ask for all four of these magic chords at once,
we get 13-limit meanpop, for which 50-et is a good choice.

Consider what happens to the "thirds" scale discussed above when the
temperament is meanpop. The 5-limit JI scale is

! thirds.scl
!
Major and minor thirds
paralleogram
12
!
25/24
10/9
6/5
5/4
4/3
25/18
3/2
8/5
5/3
125/72
48/25
2

If we take the 50-et version of this, we get

! wreckpop.scl
!
"Wreckmeister" 13-limit meanpop (50 et) tempered
thirds.scl
12
!
72.000000
192.000000
312.000000
384.000000
504.000000
576.000000
696.000000
816.000000
888.000000
960.000000
1128.000000
1200.000000

The 0-4-7 triads for this goes

[432, 312, 744]
[384, 312, 696]
[384, 264, 648]
[432, 312, 744]
[384, 312, 696]
[384, 312, 696]
[432, 264, 696]
[384, 312, 696]
[384, 312, 696]
[432, 312, 744]
[384, 264, 648]
[384, 312, 696]

We have six meantone major triads, [384, 312, 696], but we also have
three ratwolf triads [432, 312, 744], and two as yet unnamed magical
[384, 264, 648] triads. Finally, we have a nice, old-fashioned
supermajor triad, [432, 264, 696]. Each scale step has a triad, magic
or mundane, to go with it (plus the minor versions of course.)

This is, of course, related to my Wreckmeister A scale, which however
I only tempered via 126/125 planar. Looking at the matter from the
point of view of meanpop seems like a much better way to go about
Wreckmeistering.