Yer
Introduction
Yer is an octave-reduced Euler-Fokker genus of 11, 13, 17, and 19. As such it is a 2.11.13.17.19 limit just intonation tuning (ignoring the 3rd, 5th, and 7th harmonics) which is octave-repeating.
| name | frequency multiplier (definition) | frequency multiplier (decimal) | pitch (¢) |
|---|---|---|---|
| 1 | 1/1 | 1 | 0 |
| 13 * 17 * 19 | 4199/4096 | 1.025146484 | 42.9960874 |
| 17 | 17/16 | 1.0625 | 104.9554095 |
| 11 * 13 | 143/128 | 1.1171875 | 191.8456041 |
| 11 * 13 * 17 | 2431/2048 | 1.187011719 | 296.8010136 |
| 19 | 19/16 | 1.1875 | 297.5130161 |
| 17 * 19 | 323/256 | 1.26171875 | 402.4684256 |
| 11 * 13 * 19 | 2717/2048 | 1.326660156 | 489.3586203 |
| 11 | 11/8 | 1.375 | 551.3179424 |
| 11 * 13 * 17 * 19 | 46189/32768 | 1.409576416 | 594.3140298 |
| 11 * 17 | 187/128 | 1.4609375 | 656.2733519 |
| 13 | 13/8 | 1.625 | 840.5276618 |
| 11 * 19 | 209/128 | 1.6328125 | 848.8309585 |
| 13 * 17 | 221/128 | 1.7265625 | 945.4830713 |
| 11 * 17 * 19 | 3553/2048 | 1.734863281 | 953.786368 |
| 13 * 19 | 247/128 | 1.9296875 | 1138.040678 |
It has a minor third of 19:16 and a minor second 17:16.
EFG, CPS
Every pitch in the system is a combination of either zero, one, two, three, or four of 11, 13, 17, or 19, for a total of 1 + 4 + 6 + 4 + 1 = 16 pitches. In other words it is the powerset of {11, 13, 17, 19}.
If anyone is familiar with Erv Wilson’s Combination Product Sets, or CPS's, it may help to think of an Euler-Fokker Genus as the intersection of the choose-1 tetrany, the choose-2 hexany, and the choose-3 tetrany, plus the unison, plus 11 * 13 * 17 * 19 all together which may be called the aota, an acronym for “all of the above”.
As an EFG, it has no subharmonic factors, that is, no division - only multiplication of them together, which leads to it being ambitonal, not otonal or utonal leaning. While it is nicely “balanced/symmetrical” as all CPSs are, pitches in the resultant system are not evenly distributed. There are two massive gaps of 185 cents, and two places where pitches land almost directly on top of each other.
Since the EFG system of Yer includes both 11 * 13 * 17 and 19 as pitches, that means the comma exists as an interval in the scale. Since it’s so tiny, though, the two notes related by it can hardly be treated as separate. This means that when you go to draw this tuning out as a JI lattice, you can do something you wouldn’t normally do, which is set a couple points right together.
You could think of this lattice as a pair of cubes. One is an Euler-Fokker genus of [11, 13, 17]. The other is that same Euler-Fokker genus, just with every node multiplied by 19. That’s why every point in the second cube has the same set of circles colored in as the analogous one in the other cube, just with the magenta 19 filled in as well.
So every point in the first cube is connected to the analogous node in the second cube. Normally the node for 19 would not have any direct connection with the node 11, 13, 17. It only directly connects with one node in the other cube, its analogous one, the unison. But here we see that not only is there another effect going on connecting these two nodes, that effect goes beyond connecting them, it straight up conflates them.
Commas
Those pitches right on top of each other are a feature, not a bug. The pitch 11 * 13 * 17 is 2431, only one off from the pitch 19, which when octave adjusted is 2432. So we end up with this superparticular ratio, 2432:2431, the Blumeyer comma.
| name | value | cents | monzo |
|---|---|---|---|
| Blumeyer comma | 2432/2431 | 0.71200249782 | | 7 0 0 0 -1 -1 -1 1 > |
| Blume comma | 2057/2048 | 7.59129422992 | | -11 0 0 0 2 0 1 > |
Yer supports 240 possible comma pumps (which are zero comma pumps via comma shifts by the comma-wide intervals present in the tuning).
Scala file
! blumeyer_ji.scl ! Blumeyer JI scale, combination of CPS's of 11, 13, 17, 19 16 ! 4199/4096 17/16 143/128 2431/2048 19/16 323/256 2717/2048 11/8 46189/32768 187/128 13/8 209/128 221/128 3553/2048 247/128 2/1
Video explanation
More details are presented in this video: Yer (pitch system)
Listening
Douglas Blumeyer - Tsraxcfaubdj