Ok so I know you have been working on getting to know the major scale chord quality and how to build a major chord. Lets do a quick review. Knowing that the major scale has a formula (refer to previous blogs), this shapes the key signatures. If you count up three from any scale degree and then count up five from the same scale degree within the key signature you will build major, minor and dimished chords naturally. Example:
G A B C D E F# G This will give you a G major chord (it's within the key)
1 3 5 GBD Major chord
G A B C D E F# G This will give you a A minor chord (it's within the key)
1 3 5 ACE Minor chord
Now lets look at how to build minor, diminished, and augmented chords from a major chord. If you know how to build major chords from and note you will need to know how to build other chords from that same note. Example:
G B D is a G major chord
G Bb D is a G minor chord
G Bb Db is a G diminished chord
G B D# is a G augmented chord
So here is the formulas. Remember this is based off of knowing the major chord first. To get a minor chord from a major chord all you do is flat the third a half step. Notice the G major chord went from G B D to G Bb D. The B of the G major chord went to a Bb. That is what creates that minor sound. Try this on your bass. Play the major chord arppeggio and then the minor arppeggio and listen to the difference.
To get a diminshed chord you will flat the third and the fifth of a major chord. Notice that the G major chord goes from G B D to G Bb Db. Now play this arppeggio on your bass along with the other two and listen to the difference.
To get a augmented chord you will have to raise the fifth of the major chord a half step. Notice that the G major chord goes from G B D to G B D#. Now play this arppeggio along with the other three and notice the difference.
Here is a chart of major and minor arpeggios to help you get started....Hope this helps