1953 scale

The 1953 scale is my (Mason Green's) name for a nineteen-note subset of 53edo (a MOS). It is a 15L+4S scale (it has 15 long intervals 3 Holdrian commas wide, plus 4 short intervals 2 Holdrians wide).

This scale offers a possible alternative to 19edo as a way of expanding beyond 12edo. Unlike 19edo, whose fifths are all significantly flat, the 1953 scale has nearly perfect fifths, making it sound potentially more like 12edo. Its major thirds are also significantly better than those of 19edo.

However, only thirteen of the nineteen fifths are near-perfect; the other 6 fifths are flat at 679 cents, which is close to the Pythagorean wolf fifth.

Although the abundance of wolf fifths might seem like a disadvantage, composers may use them strategically to add expression to a piece (as blue notes). Another option is to use them as melodic intervals (in melodic lines or modulation) rather than played together harmonically, which lessens the unpleasant effect of the "wolfiness" and can also be used to add expression.

The generator for this scale is a just minor third, making this a Hanson MOS. One thing that 19edo and 53edo have in common is that both have near-just minor thirds; thus, using minor thirds to generate a 19-note scale in 53edo is a natural option.

Because it has only nineteen notes, the 1953 scale is ideal for keyboard instruments (19-keys-per-octave pianos do exist and have been made for centuries, although they are less common than their 12-key cousins). The Skip fretting system 53 3 14 for stringed instruments also makes this scale intuitively accessible using only the open strings and first four frets, while still allowing the full gamut of 53edo further up the neck.

This scale's 5-limit performance is amazing; in the 7-limit department it does not perform as well unless we choose to use a non-patent val for 7 (which tempers out the septimal comma, much as 19edo itself does). The harmonic seventh tetrad can only be voiced using this alternate val, but it's possible to voice the subminor triad (6:7:9) using the patent 7 as well.

The eleventh harmonic does not appear (although this might not necessarily be a bad thing for those who consider it naughty). The thirteenth harmonic does appear and the half-suspended triad 10:13:15 is common. This makes the 1953 scale an ideal scale for exploring the possibilities of the 13th harmonic alongside the more familiar 5 and 7, and it can be considered a tuning of the 3.5.7.13 subset.

The distances (in 53edo scale degrees) between adjacent notes of the 1953 scale are 3, 3, 3, 3, 2, 3, 3, 3, 3, 2, 3, 3, 3, 3, 2, 3, 3, 3, 2.

In terms of absolute positions within 53edo, this translates to 0, 3, 6, 9, 12, 14, 17, 20, 23, 26, 28, 31, 34, 37, 40, 42, 45, 48, 51.

Interval	Multiplicity	Generic interval	Width in degrees of 53edo	Approximate ratios
Quarter tone	4	1	2	49/48, 36/35, 33/32
Third-tone	15	1	3	27/26, 26/25, 25/24
Diatonic semitone	8	2	5	16/15, 15/14, 14/13*
2/3-tone	11	2	6	15/14*, 14/13, 13/12, 27/25
Minor whole tone	12	3	8	10/9
Major whole tone	7	3	9	9/8
5/4-tone, tempered septimal whole tone, tempered septimal minor third	16	4	11	15/13, 8/7*, 7/6*
Patent septimal minor third	3	4	12	7/6
Pythagorean minor third	1	5	13	32/27
Pental minor third	18	5	14	6/5
Tridecimal neutral third	5	6	16	16/13
Pental major third	14	6	17	5/4
Patent septimal major third	9	7	19	9/7
Tempered septimal major third, Barbados third, father	10	7	20	9/7*, 13/10
Perfect fourth	13	8	22	4/3
Wolf fourth	6	8	23	27/20
Tridecimal augmented fourth, tempered lesser septimal tritone	17	9	25	7/5*, 18/13
Patent lesser septimal tritone	2	9	26	7/5
Patent greater septimal tritone	2	10	27	10/7
Tridecimal diminished fifth, tempered greater septimal tritone	17	10	28	10/7*, 13/9
Wolf fifth	6	11	30	40/27
Perfect fifth	13	11	31	3/2

Approximations using the alternate (non-patent) val for 7 are shown with an asterisk (*).

The 1953 scale, like the diatonic scale, possesses Myhill's property. It is also strictly proper (whereas the 12-equal-tempered diatonic scale is proper, but not strictly proper).

Modes

The most interesting modes are the ones that have both a perfect fifth and fourth above the root (neither being a wolf). There are seven such modes. They are:

• 3, 3, 2, 3, 3, 3, 3, 2, 3, 3, 3, 3, 2, 3, 3, 3, 2, 3, 3

• 3, 2, 3, 3, 3, 3, 2, 3, 3, 3, 3, 2, 3, 3, 3, 2, 3, 3, 3
• 3, 3, 2, 3, 3, 3, 3, 2, 3, 3, 3, 2, 3, 3, 3, 3, 2, 3, 3
• 3, 2, 3, 3, 3, 3, 2, 3, 3, 3, 2, 3, 3, 3, 3, 2, 3, 3, 3,
• 3, 3, 3, 2, 3, 3, 3, 2, 3, 3, 3, 3, 2, 3, 3, 3, 3, 2, 3,
• 3, 3, 2, 3, 3, 3, 2, 3, 3, 3, 3, 2, 3, 3, 3, 3, 2, 3, 3
• 3, 3, 3, 2, 3, 3, 3, 3, 2, 3, 3, 3, 3, 2, 3, 3, 3, 3, 2