Watch the Change Chord Quality online guitar lesson by Vicki Genfan from Acoustic Rhythm Survival Guide
The quality of a chord tells us whether it's a MAJOR, MINOR, DOMINANT, DIMINISHED or AUGMENTED. Changing the quality of a chord in an unexpected place will make the ear perk up. It's a great way to lead into a new section, or to bring attention to a particular lyric or poignant point in the music.
You might also play around with using this tool in a very particular way to lead you to a new key. The V chord in any key has the feeling of wanting to 'resolve' to the Tonic or I chord. If you take a major or minor chord and change it into a V7 chord (1-3-5-b7), it will lead the ear to the I chord in a new key. For example, try playing our progression, G-D-Em-C and taking that C chord and playing an extra measure of C7... now it has the 'feeling' of a V7 chord in the new key of F.
Try doing the same thing with the Em chord....play it once and then change it to an E7 chord and it will have the feeling of a V7 chord in the key of... A!
Note about cover tunes: In legal terms, a 'song' consists of a melody and lyrics, or just melody if it's an instrumental. What this means is that you can play around all that you want (and still be within the law!) as far as changing chords, chord qualities, rhythmic motifs, tempo, time signature and all other aspects of arranging!!
SO –you too can have fun with all of this!!