Hi folks,
I’ve been trying to use the Striso for playing 31 TET and I just can’t understand what the layout is supposed to be! Namely, I can look at the key diagram for the Striso and see where the notes shared with 12 TET are, but I have no idea how I’m supposed to play double sharps and double flats! I can transpose up and down octaves, I can’t transpose “left and right” to sharper or flatter tones. Am I just misunderstanding this layout? Is there any way to play all the notes in the 31 TET scale? Thanks for your help!
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Thanks for your question, and for asking about a very nice feature that’s probably not used very often. I’m talking about the free transpose function: While playing a note, press both transpose up and down buttons at the same time, then play the new key for the played note. All notes are now transposed by this interval so you can continue playing the tune from the last pressed key.
It’s mentioned in the quick start guide, but might be easy to miss.
There’s also semitone transpose, but at the moment that’s fixed to 100 cent, I’ll change that to using the current tuning minor second interval in the next firmware release, that makes more sense.
Let me know how well free transpose works for you! (And if you feel like making a demonstration video you’ll make my day!)
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If my understanding of the 31-Tet Wicki-Hayden layout is correct (hard to find exact diagrams for it online), the neutral third in 31-TET would be off the board, correct? This seems pretty impractical for playing music which cares about the neutral third quite a bit (i.e. The Blues). Are there alternative layouts that would make reaching the neutral third on the Striso more practical while still preserving isomorphism?
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Actually, mapping it out by hand I think there would actually be a few neutral thirds on the board, namely between D# and G flat, G flat and A#, and A# and D flat. Annoyingly, it does not appear possible to get both the neutral 3rd and harmonic 7th of the same key on the board at the same time using free transpose, assuming the default layout works the way I think it does (up and to the right = 5 steps, up and to the left = 13 steps).
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I think you’re right about those neutral thirds, they’re at the very edge of the board so that doesn’t leave many options. As far as I can see there is one possibility for the neutral 3rd and harmonic 7th together: G♭ - A♯ - E.
And welcome to the forum!
Piers
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Thanks for the reply and the warm welcome!
You’re right, I missed a few harmonic sevenths when I was mapping this out the other night.
Since then, I did try to come up with a few alternative layouts that put all 31 notes of 31 TET on the board at once, and while I think I came up with a few promising ones (step sizes of 5 and 4 that spread out the octave over more rows, and a spicier layout based on Orwell[9] with step sizes of 4 and 11). I’ve come to the unfortunate conclusion that 61 keys is just a bit too small to layout all 31 notes of 31 TET. Simple math tells us that we can’t even get a full 2 octaves, and most layouts will have some duplicate keys, so we’ll need more than strictly necessary to allow us a little flexibility so we can actually close those two octaves.
As things are, the default wicki-hayden layout is probably the best you’re going to get for 61 keys. You still have the same range as 12-TET, and all of the missing notes are within 1 step of notes you do have, so if you need to access them quickly without transposing, you could likely tune your maximum pitch bend amount to the dieses (1 step in 31 TET) and bend down or up to the desired pitch from a nearby note. For situations where you need to play in a key that uses a bunch of half sharps, double sharps, half flats, or double flats, you could use free transpose like you mentioned. (I’m pretty sure you can freely transpose any note to any other note in a single step, I just need to verify that all 31 intervals of 31 TET are present somewhere on the board.)
As for how many keys you WOULD need for a practical full 31 note layout, my attempts at finding a layout seem to indicate you would want at least an extra row on top and bottom (61 + 2(2 + 3 + 2) = 75 keys). This would have the added benefit of bringing the range of the default Wicki-Hayden layout to a full 5 octaves (and some change) from C1 to C6 (equivalent to a full organ manual of 61 keys). Annoyingly, most of the layouts I tried also require adding the C flat and E sharp columns in order to fill in the last few missing notes (75 + 2(5) = 85 keys). This is likely a harder sell as these keys already have enharmonic equivalents in 12 TET, but I don’t think 31 TET is the only system where this isn’t the case, and even 12 TET benefits a bit from having to wrap fewer chords and scales to the other side of the board.
I realize that this likely isn’t that much of a priority, but maybe something to consider for the future if you were ever considering making a larger variant.
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