Ya! I myself would love to know how to do this. Apparently you need knowledge in music theory and I don't really get it. I would have to try this entirely by what sounds right to me! I did go searching for an explanation and found this. Maybe it would help you....If your like me, maybe not so much!
This was answered on "Yahoo Answers"-
Devon answered 10 months ago
It most certainly is possible to do an entire major/minor transposition like this, but it requires some music theory knowledge.
G, D, Em, C progression in G major becomes Gm, D, Eb, Cm.
Why? It's based on scale degrees of the chords.
There are 7 notes in every scale (8 to complete the octave). Each note in the scale can be given a number from 1-7.
Just as there are 7 notes to a scale, there are 7 chords found in that scale, all based off of the different notes in that scale.
In G major, G would be 1, A is 2, B is 3 and so on. So the progression you have here is what we call a "I-V-vi-IV" progression in major because G=1, D=5, E=6 and C=4.
Translating a key to its parallel minor requires you to flatten (lower) the 3rd, 6th and 7th notes in the scale by a half-step to give it the "dark, sad, minor feel." Similarly, you have to do the same for chords built off of these notes.
In the key of g minor, the 3, 6 and 7 are lowered, melodically, while harmonically, only the 3 and 6 are lowered. So a scale changes from G-A-B-C-D-E-F#-G in major to G-A-Bb-C-D-Eb-F(F# in harmony)-G
As stated before, you have a 1-5-minor6-4 progression. So to translate to minor:
1) change all major chords to minor. This will give you a "i-v-vi-iv" (minor1-minor5-minor6-minor4) progression in a minor key.
2) find anywhere you have a 5 chord (D in the key of G) and make that major. The 5 chord will 99% of the time be major in any minor key (due to dominant function, which is another subject altogether). You should now have a "i-V-vi-iv" progression
3) find your 3 and 6 chords and lower them by a half step. In G, E (the 6th note in a G scale) becomes Eb (E flat)
4) change your originally minor chords to major (the exceptions are the 2 chord, which becomes half-diminished and the 7 chord, which is fully diminshed in minor. Don't worry about the restrictions on this rule if you don't have 2s or 7s). You should now have a "i-V-VI-iv" progression and have finished the harmonic transposition.
5) Change the melody to have the properly flattened notes so it fits with the altered chords.
6) Play your progression and listen to it!
Hope this helps! Good luck!
Source:
Trombone Performance Major in University, Minor in Composition and Arranging.
This concept is taught in Theory I-II and put into practice in Composition/Arranging I
