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Two 21-tone JI scales: detemperings of blackjack

🔗Paul Erlich <paul@stretch-music.com>

9/11/2001 1:32:06 AM

Here's a JI convex detempering of blackjack that seems to give the
most possible pure 4:5:6:7 chords (six of them). Is that right?

Go to

/tuning/files/perlich/scales/

and download

blackjack6.gif

The JI scale is as follows:

ratio note cents
1/1 E[ 0
50/49 Ev 35
15/14 F< 119
320/147 F 147
8/7 Gbv 231
7/6 Gb^ 267
60/49 G 351
5/4 G> 386
21/16 Ab^ 471
4/3 A[ 498
7/5 A> 583
10/7 Bb< 617
3/2 B[ 702
32/21 Bv 729
8/5 C< 814
80/49 C 849
5/3 C> 884
7/4 Db^ 969
25/14 D[ 1004
15/8 D> 1088
40/21 Eb< 1116

The step sizes are

50/49
21/20
64/63
21/20
49/48
360/343
49/48
21/20
64/63
21/20
50/49
21/20
64/63
21/20
50/49
49/48
21/20
50/49
21/20
64/63
21/20

If change the note G by 2400:2401 we have this lattice instead:

Go to

/tuning/files/perlich/scales/

and download

blackjacksup.gif

The scale is

ratio note cents
1/1 E[ 0
50/49 Ev 35
15/14 F< 119
320/147 F 147
8/7 Gbv 231
7/6 Gb^ 267
49/40 G 351
5/4 G> 386
21/16 Ab^ 471
4/3 A[ 498
7/5 A> 583
10/7 Bb< 617
3/2 B[ 702
32/21 Bv 729
8/5 C< 814
80/49 C 849
5/3 C> 884
7/4 Db^ 969
25/14 D[ 1004
15/8 D> 1088
40/21 Eb< 1116

with step sizes

50/49
21/20
64/63
21/20
49/48
21/20
50/49
21/20
64/63
21/20
50/49
21/20
64/63
21/20
50/49
49/48
21/20
50/49
21/20
64/63
21/20

This could satisfy Kraig Grady, and perhaps even Pierre Lamothe,
despite the loss of a tetrad relative to the first scale. Pierre, any
comments on this last version?