Hi PG developers,

As a saxophone player, I very much enjoy BiaB’s ability to transpose the notation for my instruments. Most of the time transposition in BiaB works great, as long as the song stays in one key. But, you can see some strange results when harmonies start to wander outside the key. Often, the resulting chords would not be found in any major or minor keys because they would need double sharps or double flats to be spelled correctly with the chord roots that BiaB chooses. There are also some problems when the new key is Gb major or certain minor keys.

For the past few weeks, I have been analyzing how BiaB transposes, and then analyzing what chords occur on sharps or flats in every major and minor key, and finally coming up with some suggestions to fix the problems that I have seen.

I will post each of my ideas separately within this discussion thread, and I hope that you will consider each one of them.

Thanks,
Jim

F5 Key Change option that works for transposition

Songs often modulate, whether it just two measures of a ii – V – I in another key, or an eight-bar bridge, or a final chorus that is higher than the rest. If you are only working in concert pitch in BiaB then you will be able to type in the chords that are correct for each of the modulations, and you also have the option of changing the key signature at any measure (except the first). The problem comes when you try to transpose the song. BiaB will base the chord roots for the whole piece on the key the song starts in. For instance, say you have a song that modulates up a half step, and you transpose the song or the notation so that it begins on Bb. The second section should now be in the key of B, but because the first key in the song was a flat key, all the chords that ought to start on sharps in B will start on flats instead.

I would like a way to keep the chords diatonic to the new key. I.e., In B major: B C#min, D#min, E, F#7, G#min, A#minb5. And I also want the notes in the new key to be written in the new key signature, not as enharmonics.

My proposal is for you to replace the “Key Signature Change To” feature in the F5 menu with a revised version that will work for transposing. Here are my suggestions for the proposed feature to replace it.

1. Call it “Key change to”, and, to make it more useful for brief “key of the moment” modulations, have a check box for “Change key signature”, which should be checked by default. Unchecking it should not affect the way chords and notes are chosen compared to keeping it checked, but would only affect whether accidentals are needed in the notation.
2. The key changes marked by using this feature would be transposed when the song is transposed.
3. Chord roots, starting at this point, should be named based on scale tones of the new key.
4. Notes, starting at this point, should be named based on the new key. If the new key contains an E#, it should be written as such, and not as an F.

#7 in minor.

When the root of a chord is the raised seventh degree of a minor key, and it is a “black key” it should always be displayed as a sharp, not a flat.

This currently works correctly in BiaB in some circumstances, but not in others. Where it works:
- When it is the third of a V chord, such as D7/F# in the key of G minor.
- On i chords with a major seventh in the bass (with one exception), such as A/G#
- In concert key notation it also works most of the time for diminished seventh chords such as G#dim in the key of A minor (also with one exception).

Here are the circumstances where the raised seventh of a minor key is not displayed correctly:
- When transposing to the key of G minor the F# roots are incorrectly displayed as Gb, as in Gbdim and Gmin/Gb. These should be F#dim and Gmin/F#.
- When transposing the notation for non-concert pitch instruments, the roots of diminished seventh chords are incorrectly displayed as flats -- Dbdim, Ebdim, Gbdim, Abdim, Bbdim – they should be C#dim, D#dim, F#dim, G#dim, A#dim.

Keys with 6 sharps or flats.

When transposing to the major key of Gb/F#, please use F# major instead of Gb.

The first reason for this request has to do the BiaB feature which simplifies chord roots starting on Cb, E#, double sharps, or double flats to their enharmonic equivalents starting on naturals. In either Gb major or in F# there are some trade-offs because these keys have 6 flats or 6 sharps while there are only 5 “black keys”. BiaB won’t write chords starting on Cb or E#, but simplifies them to B and F. Since the extra flat in Gb major occurs on the very important IV degree of the scale, Cb, which BiaB will always writes as a B (a sharp chord in the middle of a flat key) that is a major disadvantage for Gb major.

The trade-off with F# is that the extra sharp in F# major is E#, which BiaB will always write as an F. However, since the chord on this scale degree the vii of the key, and since vii chords are much less common than IV chords are, it would be much better to use F# major than to use Gb major when transposing to this key.

The second reason to use F# major instead of Gb major has to do with a major audience for the transposing feature. While any musician or composer may transpose songs occasionally, players of transposing instruments are constantly transposing the notation of songs to compensate for the pitch of their instruments. Most transposing instruments are in flat keys, and to compensate for our instruments in Bb and Eb we are always removing two or three flats from flat keys, and adding two or three flats to sharp keys. Consequently, this makes us much less used to playing in keys with many flats, and much more familiar with playing in keys with many sharps.

Please continue to use the key of Eb minor instead of D# minor for six flats or sharps because more of the notes and chords can be spelled correctly in Eb minor when you consider the raised seventh.
- In D# minor the #7 is C##, which will get simplified to D in BiaB. The D is spelled correctly in Eb minor as the root of the Ddim chord and as the third of the V chord, Bb7.
- In D# minor the ii is E#, which will get simplified to F in BiaB. The F is spelled correctly as the root of the important ii chord in Eb minor.
- In Eb minor, the note that BiaB will simplify is Cb, the bVI chord, which is less important than the ii, V, and vii, so the key of Eb minor wins out over D# minor.

Diminished chords starting on #, not b

Diminished chords and half diminished seventh chord starts should not be built on flat roots. Use sharp roots instead.

- Diminished and half diminished chords never occur on flat roots in any major or minor key.

- Also, spelling any diminished chord as a stack of thirds without enharmonics results in chord tones with double flats, Cb, and Fb, whereas if you start on sharp roots those same tones are naturals.

Therefore, this rule should take precedence over BiaB’s preference to build chords on scale tones.

Chords built on non-scale tones - Quality of chord

The quality of the chord should be a factor in how BiaB chooses whether the root should be a sharp or a flat. This suggestion applies when:
- When the root of a chord is not a scale tone of the selected key,
- and it falls on one of the black keys on the key you are transposing to.

I based the following suggestions on analysis of all the chords diatonic to the major keys with up to 5 flats and 6 sharps, as well as the V7 of each minor key. As you change the quality of chords from diminished, to minor, to dominant seventh, to major, and finally to Augmented, more and more roots start on flats instead of sharps.

I already requested that if the chord is diminished or half diminished, the root should be sharp, regardless of whether the root is a scale tone in the key

If the chord is Augmented, use flats for the roots.

For minor, dominant seventh, and major chords, use the following for chord roots that are not scale tones:

If the root in the new key is F#/Gb, use F#.

If the root in the new key is C#/Db then
if the quality is minor or dominant seventh, then use C#
else, use Db (for major chords)

If the root in the new key is G#/Ab,
if it is a dominant seventh and it is preceded by D#minb5 then use G# (it is the V of C#min)
if it is minor, use G#
else, use Ab (for major and dominant seventh chords)

If the root in the new key is D#/Eb then
if it is a dominant seventh and it is preceded by A#minb5 then use D# (it is the V of G#min)
else, use Eb (for minor, major and dominant seventh chords)

If the root is Bb/A#, use Bb.