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I have a keyboard, a Roland RS-50, and I have been playing around in D Double Harmonic major a lot recently. That Wikipedia article says that you can play the scale with quarter tones, and I'd like to try this as I've never played with quarter tones before. On page 58 of the keyboard owner's manual (linked above) it says you can individually tune any note of the scale up by 63 and down by 64.

My problem is this: tuning down D# by the full 64 doesn't make it reach D (in equal temperament tuning in which all notes are set to 0) but it seems to get quite close.

How do I tune it to exactly 1 quarter tone down? What are the degrees in this tuning setting?

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The Roland manual https://static.roland.com/assets/media/pdf/RS-70_50_MI.pdf says the tuning ratio is one cent (100 cents = 1 semitone) for each MIDI value, with 64 making no adjustment.

So to tune a note in quarter tones, you want to set to set the values for each note to 14 (down a quarter tone), 64 (no change), or 114 (up a quarter tone)

Note, I don't have a RS-50, so I have no way to check this is correct.

Apparently, you can't tune a note up or down a full semitone - but to change from one temperament (tuning system) to another, you are unlikely to need to do that anyway. The fact that you can only adjust the tuning in 1-cent intervals is often a bigger limitation - you might think an error of 1/100 of a semitone is inaudible, but sometimes it isn't! For example the difference between an "equal temperament" 5th and a just intonation "perfect" 5th is a bit less than 2 cents, so a 1-cent accuracy is actually quite poor. A good piano tuner can do better than that "by ear" without using an electronic tuner.

  • That helps a lot actually, i was playing around with the just intonation preset and I kept thinking it sounded really out of tune. Glad it's not just me. – Douglas Sep 1 '17 at 22:47
  • Actually it can get worse than the 1 cent increments imply. I don't know about Roland, but the old Creative cards had the same 1 cent increment in the user interface, but the actually card changed pitch in increments of about 0.4 cents, so if you asked for 1.0 cents, you might get anything between 0.6 and 1.4! In fact you could get smaller changes than 1 cent by using pitch bend commands, but that only worked for monophonic instruments. Since the Creative cards used soundfonts for the samples, you could do even better by changing the sample playback rate from 44100 to a number like 44073 ... – user19146 Sep 1 '17 at 23:57
  • One way to test would be to tune B (for example) up to 114 and C down to 14 and see if they are the same note. – Todd Wilcox Sep 2 '17 at 6:42
  • I mainly hear that piano tuners can detect note differences that are less than 1 cent by playing both notes simultaneously and checking whether a pulsing beat remains. I suspect that those piano tuners wouldn't be able to detect the difference by ear if each note were isolated. – Dekkadeci Sep 2 '17 at 14:07
  • @Dekkadeci alephzero is talking about tuning intervals, not absolute pitches, so your comment doesn't really apply – Some_Guy Sep 3 '17 at 3:16

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