What is the difference between the c sharp major and d flat major scales?

Answer 1

In the history of even-tempered scales, prior to the introduction of the concept of equal temperament, a system existed called "just intonation", where the ratios between notes were such that the precise difference between a single sharp note (for example, the G sharp as mentioned in the question) and its enharmonic equivalent, A flat, would possess a slightly different frequency. The concept of equal temperament was favoured by lutenists and flautists until around 1800, at which point the concept of "just intonation" became the in thing.

Therefore, in the days prior to the entire conversion to even temperament, there were still some musicians who favoured the system. Meanwhile, others found problems. One musician, Samuel Sebastian Wesley, who lived, as the grandson of hymnist Charles Wesley, during the nineteenth century, despised the system all along and was perfectly happy with the previous system.

Nowadays, a twelve semitone octave is divided evenly throughout the logarithmic scale - the difference in frequency between one note and any note n semitones above is equal to the twelfth root of 2 to the power n, in the logarithmic scale - and today, the two scales would sound the same. However, it is necessary at this point to look at the note-by-note make-up of each scale, considering that each scale must have one note of each letter name incorporated into it. First, the scale of G sharp major:

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

Note the rare inclusion of the note B sharp (which runs directly alphabetically from the previous note, A sharp) and the inclusion of the F double sharp, which has the effect of adding two semitones to the given note. It follows that it would be nigh on impossible to find a piece of music which is based in the key of G sharp major, while its enharmonic melodic minor equivalent, G sharp melodic minor, contains the same sharps as the B major scale. This is thus much more commonly seen than its own enharmonic equivalent, A flat minor, which would be enharmonically equivalent to C flat major - once again, to classical musicians, a pique of interest, but a mostly useless key in pre-20th Century works.

With that said, the key of A flat major is much more commonly found. Its notation is much simpler, thus:

Ab Bb C Db Eb F G Ab

Its relative melodic minor scale, F melodic minor, is much easier to notate than that of its enharmonic equivalent's relative melodic minor, E#. The scale for F melodic minor runs as follows:

Ascending: F G Ab Bb C D E F

Descending: F Eb Db C Bb Ab G F

Note that when ascending in any melodic minor scale, the submediant and leading note are raised by a semitone, and when descending, the notes are flattened back to their equivalents in the relative major.

In an evenly tempered scale, the frequency of the A flat above middle C is approximately equal to 415.3 Hertz. It is harder to specify what the frequency of a note in a non even-tempered scale is, as there are several varieties of the same scale used at various times.

In a nutshell, the key you are most likely to find in written music is A flat major. Perhaps oddly to the non-musician, in its minor form, the key you are more likely to come across in its minor form is G sharp minor - once again because of convenience of use - G sharp minor contains five sharps, while A flat minor contains seven flats.

Answer 2

In C major scale you don't have any sharps or flats, but in G major scale you have F sharp.

Hope this helps

Answer 3

There is no difference. They are different names for the same scale.

Answer 4

The g- major scale starts on G.