Many students know their major and minor chords but have not wuite conquered 7th chords. Likewise, many students know how to make a 7th chord but have not quite conquered the 9th chords.
Here is the secret. If you don’t know 7ths yet, when you come to a 7th, just drop the 7 and play a major or minor chord. Or if you know 7ths but not 9ths yet, when you come to a 9th chord, just play a 7th instead.
Now, while this will sound good, remember that playing the “higher number” chord will always sound better. (In other words, 9th sounds better than 7th because it had a fuller sound and 7th sounds better than plain major or minor chord, etc).
(When I say 7th chord, I mean all types of 7th chords – major 7th, minor 7th, dominant, augmented, diminished, etc. Same for 9ths.)
In other words, if you come to a C7 and don’t know 7ths yet, just play C major. Or if you come to Am7, just play Am. It won’t sound as good, but it will work fine.
Likewise if you don’t know 9ths but know 7ths and come to a Cmaj9, just replace it with a Cmaj7. Or replace Dm9 with Dm7.
Now, that being said, if you don’t know 7ths or 9ths and you come to 9th such as C9, just play the major or minor chord equivalent.
So for C9, play C major. For Cm9, play Cm, for Cmaj9, play C major etc.
Hope this helps a lot of you folks out there.
– Richard W. Smith
Apostolic Praise School of Music