Theoretical key support

• Nov 18, 2017 - 19:06

Hello everyone,

It would be a nice addition if theoretical keys (with 8 or more (i.e. involving double) sharps/flats, e.g. G-sharp major or F-flat major) were supported in MuseScore. It can help both with adjusting the parts for transposed instruments (showing in an enharmonical keys), or just for score writing (e.g. one of my composition begins in A-flat major and ends in G-sharp major, with meaning "things are returned to their places but the situation has significantly changed", so I cannot just use A-flat since it would ruin the whole main idea. Currently, I've sticked to using C-sharp major and explicitly writing all double sharps).

Although I'm a C++ developer, I'm not sure that I can contribute to this (and that community will accept it).

Thank you in advance and sorry for my bad English.


Welcome aboard... you wrote: composition begins in A-flat major and ends in G-sharp major, with meaning "things are returned to their places but the situation has significantly changed", so I cannot just use A-flat since it would ruin the whole main idea.

For listening/playback purposes how does the whole main idea get ruined by only using A-flat? Doesn't the A-flat major scale sound the same as the G-sharp major scale?... Especially nowadays, with equal temperament tuning. ;-)

However... and here's the distinction:
The A-flat major key signature does look different from the G-sharp major key signature; and, as Jojo mentioned, custom key signatures can be created and then saved to a custom palette for future use:


This way, you can look at the G-sharp major key signature to see that ..."the situation has significantly changed". (Such as for harmonic analysis of the written score in order to comprehend the whole main idea.)

The link above (and Jojo) mentions:
Playback of custom key signatures is not directly supported. (Though strictly for playback purposes, A-flat major should suffice, yes?)
If you insist upon playback, together with G-sharp major notation, you can 'fake it' with a hidden staff. Listen to the following attachment: A_flat_G_sharp.mscz

(After listening, open the MuseScore menu item: Edit / Instruments, then tick the 'Visible' box to see the invisible staff.)


In reply to by Jm6stringer

Yes, you're right, it works, but looks (and sounds) pretty like a "dirty hack" (or as a not-so-good workaround at least). And also, it doesn't solve the problem with transposing instruments. For example, how to write in concert E major for a transposing instrument in A-flat? Either using 4 flats (which results in F-flat major) or 8 sharps (which results in written G-sharp major) will require theoretical keys, so is impossible in MuseScore.

In reply to by trolley.813

Not sure what you mean here about transposing instruments. If you have a transposing instrument in Ab, you are welcome to write in concert E for it, and MuseScore will transpose for you when you turn off the concert pitch button. While that should theoretically produce a key with 8 sharps, the universal standard in such matters is to simplify and instead represent this as 4 flats, and that is precisely what MuseScore does.

In reply to by trolley.813

True... the MuseScore playback does not truly recognize the (G-sharp major) custom time signature; and the playback does need to be 'faked' when notating as such - which is what I demonstrated (kludged).
Also, it's true what you write: that theoretical key signatures do not work in cases like this:

Still (and probably a rarity for most MuseScorers) a theoretical time signature can be notated in a score, saved to a custom palette, and printed out, if absolutely necessary.

(I'm curious as to how often you encounter these cases. )


Theoretical key signatures are very rare. Musicians can't read them, and arrangers would rather use enharmonic key signatures, so I suspect this won't be a priority of the developers...

Also, the G♯ major key signature would go like this: C♯, G♯, D♯, A♯, E♯, B♯, F𝄪 (optionally with a courtesy F♯ beforehand if coming from a key without any sharps, like the courtesy naturals of other key signature changes).

I'd like custom key signatures to work as written for other reasons (combined with expanded microtonal accidental functionality), but I imagine it would be more effort than it's worth right now...

In reply to by mike320

I just did a quick test. I put a saxophone quartet in 5 sharps in concert pitch, then disabled and re-enabled concert pitch with the button. Now different instruments are in different keys.

Yes, I can see that functional theoretical keys are indeed useful now.

In reply to by to7m

Perhaps, but a more important solution is simply to remember the keys properly to restore them later. A;lso important to respell notes appropriately in these cases as well. There is a related open issue for this: see #18147: When silently changing the key to enharmonic equivalent during transposition, change notes too . This should be addressed regardless of whether or not someone ever chooses to force to a saxophonist to read 8 or 9 sharps.

I have a slightly different problem, I am transposing a piece of of music for saxophones and I am in the key of Concert B. That puts the Bb instruments into the key of C# and the Eb instruments into the key of G#. Luckily, Musescore automatically changed the G# into Ab, but I would rather the Bb instruments to read in Db and not C#: is there anyway to change that?

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