G-double-sharp harmonic minor key signature

The Solution below shows the G## harmonic minor key signature on the treble clef and bass clef.

The Lesson steps then explain how to write the key signature using both clefs, including the display order and line / space staff positions of the notes, and the sharp / flat accidentals.

For a quick summary of this topic, have a look at Key signature.

Solution

1. G-double-sharp harmonic minor key signature

The G-double-sharp harmonic minor scale has 2 sharps, 4 double-sharps, 1 triple-sharp.

Warning: The G-double-sharp key is a theoretical harmonic minor scale key.

This means:

> Its key signature would contain either double-sharps or double flats.

> It is rarely used in practice, because it is too complex to use.

> It is not shown as a minor key on the Circle of fifths diagram, which contains the most commonly used minor keys.

> There is always an identical harmonic minor scale that you can use in its place, which is on the Circle of 5ths.

> The A harmonic minor scale sounds the same / contains the same note pitches, which are played in the same order, and so it can be used as a direct replacement for the G-double-sharp harmonic minor scale.

These note names are shown below on the treble clef followed by the bass clef.

Rather than use a key signature that would in theory contain double sharps or flats, usually the key signature of the replacement minor scale A, above is used, as shown below.

Lesson steps

1. Piano key note names

The white keys are named using the alphabetic letters A, B, C, D, E, F, and G, which is a pattern that repeats up the piano keyboard.

Every white or black key could have a flat(b) or sharp(#) accidental name, depending on how that note is used. In a later step, if sharp or flat notes are used, the exact accidental names will be chosen.

The audio files below play every note shown on the piano above, so middle C (marked with an orange line at the bottom) is the 2nd note heard.

2. G-double-sharp harmonic minor notes

The G## harmonic minor scale has 2 sharps, 4 double-sharps, 1 triple-sharp.

To understand why the G-double-sharp harmonic minor scale has 2 sharps, 4 double-sharps, 1 triple-sharp, have a look at the G## harmonic minor scale page, which shows how to identify the note positions and names for this scale.

This harmonic minor scale is based a natural minor scale that is not on the circle of 5ths - G## natural minor scale, which means that its key signature would have double sharps or flats.

So rather than use this complex key signature, usually the key signature of a simpler equivalent scale would be used.

In ths case, the harmonic minor scale having the same note pitches played in the same order is the A harmonic minor scale, so its key signature will be used instead below.

A harmonic minor scale.

The next step will show the A natural minor key signature as a basis for calculating this harmonic minor key signature.

3. A minor key signature

The A natural minor key signature has no sharp or flat notes, which is different to the harmonic minor scale above.

To calculate the A harmonic minor scale from the A natural minor scale, the 7th note position of the natural minor scale - note G is raised by one half-tone / semitone, as shown in the next step.

However, the harmonic minor key signature next to the bass or treble clef will not reflect this raised note, as explained in the next step.

4. A harmonic minor key signature adjustments

Below is a table showing the note name adjustments that describe the difference between this harmonic scale note and the natural minor scale, whose key signature it uses.

The 7th note of the natural minor scale needs to be raised by one half-tone / semitone, which will result in adjustment action on the existing natural minor note name.

The natural minor key signature of the bass or treble clef is used, with the differences between the two scales shown as adjustments next to the note names on the staff, not in the key signature itself.

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