More about the tuning

I did a little research on the 10 strings per octave in the melody section:
 

C - C# - D - E - F - F# - G - G# - A - B

It looks like this is quite common on the "5/21" fretless zithers: 5 chords, 2 times 10 plus 1 melody. It is called "partially chromatic", which is diatonic (C - D - E - F - G - A - B) with one or more accidentals (in this case C#, F#, G#).

So why these three accidentals?
I can explain the C# and the F#: they are in the A and D chord in the chord section of the zither. For the G# string Jan Castelein, assistant engineer at Galaxy Studios, gave me the hint that it may have someting to do with the raised 5th (augmented triad, two major thirds).

Looking at the chords:

• A-chord: A-C#-E, with raised 5th is A-C#-E#
• D-chord: D-F#-A, with raised 5h is D-F#-A#, no, there is no A# string on the zither
• F-chord: F-A-C, with raised 5th is F-A-C#
• G-chord: G-B-D, with raised 5th is G-B-D#
• C-chord: C-E-G, with raised 5th is C-E-G#

How about minor chords?

• A-minor: A-C-E
• D-minor: D-F-A
• F-minor: F-Ab-C
• G-minor: G-Bb-D, no, there is no Bb (A#) string on the zither
• C-minor: C-Eb-G, no, there is no Eb (D#) string on the zither

Hmmm....