What notes do the keys of the Suiko ST-50 play so I can DIY one myself?

February 21, 2022 1:26 PM

Suiko Koto synthesizers have two rows of buttons for playing traditional Japanese music but they are not arranged like a western keyboard. In addition they can switch from equal-temperament to a traditional one (just intonation?) I want to make a simple Koto Synth using arcade buttons and a micro-controller but I need to know what tones come from each button on the bottom two rows.

YouTube has many examples of people playing the synths, often demonstrating that the notes are not in a western order. Other searches have been equally fruitless. I could just buy one and use a tuner but they have gotten expensive and my 'buying weird music things' habit is already completely out of control.

Can the hive mind help me figure out the tones (frequencies) produced by each key, ideally in both equal temperament and also the traditional tunings so I can hack together one of these things on the cheap?

I have a clue regarding traditional frequencies from the paper in the Journal of the Acoustical Society of Japan by Masateru Ando entitled Koto Scales and Tuning which describes how to tune the acoustical instrument that the Suiko ST-50 emulates (among other things.) I imagine the button arrangement mimics finger positions, but I could be very wrong.

posted by Captain Shenanigan to Media & Arts (5 answers total)

This may not be helpful, but the keys seem labeled. The handwritten kanji translator might be useful to sort it out on your own. e.g., the bottom left seems to translate to "No. 4" on top and "water" on the bottom. Someone who actually speaks the language could probably just translate it in a minute. Sadly, that's not me. (Do post your schematics to projects! I want one.)
posted by eotvos at 2:28 PM on February 21, 2022 [2 favorites]

(sorry, "No. 3," which is pretty obvious.)
posted by eotvos at 2:38 PM on February 21, 2022

Response by poster: Ooh, that kanji translator is neat!

Tell you what eotvos, if/when I wire this up I'll post the code and schematic (it won't be complicated) and I'll do a MeFi Project post. rpi pico and midi has been my thing lately. That and doing terrible horrible things to organs.
posted by Captain Shenanigan at 3:14 PM on February 21, 2022 [1 favorite]

Best answer: The note names and numbers on the buttons (using the image in this listing) read as follows (though I'm not sure what the numbers mean):

  fa♯ sol la♭ do♯ re  fa♯ sol la♭ do♯ re  fa♯ sol la♭ do♯ re
                      4
mi  fa  la  ti  do  mi  fa  la  ti  do  mi  fa  la  ti  do
            1   2   3   3'  5   6   7   8

Listening to this video, the bottom row seems to be tuned to the in scale in F, which means the notes corresponding to each button are the following:

  G   A♭  A   D   E♭  G   A♭  A   D   E♭  G   A♭  A   D   E♭
                      4
F   G♭  B♭  C   D♭  F   G♭  B♭  C   D♭  F   G♭  B♭  C   D♭
            1   2   3   3'  5   6   7   8

where the note labeled "6" is middle C. You can look up the equal-temperament frequencies for each note here.
posted by pmdboi at 3:41 PM on February 21, 2022 [3 favorites]

Response by poster: Exactly what I was looking for, thanks pmdboi!

Side note -- that video is what started me down this particular rabbit hole...

I guess this means I have to follow through with actually building one now. Warming up the soldering iron.
posted by Captain Shenanigan at 5:10 PM on February 21, 2022 [3 favorites]