# Irrational time signature playback

Hello!

It’s great that irrational time signatures (such as 4/6, 4/20) can be entered just as easily as regular ones in Dorico, however they don’t seem to play back correctly. Am I missing something, or is playback of these types of time signatures not supported yet? I’m using Dorico version 4.3.30.1132.

Thanks!

Not supported yet afaik.
Create a hidden tempo change.

Jesper

From a mathematical perspective, these are of course rational time signatures (I know this is correct usage musically). Irrational time signatures would be something like pi/8 or e/4. That would be fun!

Hi – I’m wondering if I am running into the same thing… (in Dorico 5.1)

Maybe I’m completely misunderstanding the concept here of “irrational” time signature (?)

What I was expecting to happen in the 7/12 bar is to fill it with (7) 8th note triplets… and the duration of each of those 7 notes would each be the same duration as the 8th note triplets in the 4/4 measure.

Written another way, I think the 4/4 and 7/12 bar could be written as: (12) 8th notes in a 12/8 bar, and then (7) 8th notes in a 7/8 bar… in such case, the duration of each note would for sure be the same.

Am I’m misunderstanding the “irrational” concept?

Dorico will happily print whatever denominator you enter, but for playback an eighth note is an eighth note. In order to make this play back the way you want, you must add either tempo equations, or explicit metronome marks, and hide them.

@Mark_Johnson
yes, I see that dorico lets me put any value in the denominator… (e.g., 8/19)… but that wasn’t really the question.

My question, as per the image… why does Dorico allow (7) 8th notes in a bar of 7/12? shouldn’t it be (7) 12th notes? Shouldn’t one be limited to only (4) 8th notes + (2) 8th note triplet partials) in a bar of 8/12?

What are you talking about? It’s actually (7) 12th notes,. 1 semibreve = 12 triplet 8th notes. One twelveth part of the semibreve. That’s what you’re already doing.

In short, irrational time signatures aren’t worth it unless you require specific rhythmic values that aren’t possible to be filled in normal time signatures (otherwise they would look incomplete).

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In Dorico when you write a denominator other than a standard power of 2, you get notes of the largest power of 2 less than that number. It doesn’t magically convert to fractional note durations. 7/12 (or any number from /9 to /15) gives you a bar of 7/8 – as you can see in your score. 3/5 or 3/6 or 3/7 gives you a bar of 3/4, and you have to add tempo changes to make it play back correctly.

To play 4/4–7/12–4/4 as in post #4 correctly, put q=q. at the 7/12 and q.=q at the next 4/4, so 7/12 plays the right amount faster. For more complicated proportions you may need to use actual metronome marks and do the math yourself.

See this thread for how to make the incomplete tuplet brackets required. For complete tuplets, you need to fake the ratio (e.g. 3:3), because the tempo instructions handle the speed. Is this making sense yet?

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Thanks, @Mark_Johnson … your explanation does make sense… and jives w/ what I’m seeing, and using a relative time signature was my initial thought.

@Sergei_Mozart : “What are you talking about? It’s actually (7) 12th notes,. 1 semibreve = 12 triplet 8th notes. One twelveth part of the semibreve. That’s what you’re already doing.”

I’m not sure I follow your comment … the 7/12 measure in my image has (7) 8th notes… not (7) notes that are “One twelveth part of the semibreve”.

I take your point that : “irrational time signatures aren’t worth it unless you require specific rhythmic values that aren’t possible to be filled in normal time signatures (otherwise they would look incomplete).” … e.g., as I noted above, I could notate what I’ve indicated above in various x/8 time signatures no problem… thus, this was a bit more of a question regarding my understanding irrational time signatures vs. the behavior in Dorico.