try playing
Gmajor7 instead of Gmajor. its different from G7
Yup. The type of 7th you add is going to depend on the original chord's function within the song. It's actually a
wee bit complex.
Minor chords are usually going to just get a "minor 7th" added. Examples:
A- = A-7
G- = G-7
etc.
(Oh, and I'm using a "-" to mean "minor", which is a kinda jazzy way of doing it too.
)
Major chords (which is what chords are if they're just a single letter with nothing after them) are trickier. They're generally either going to get a "dominant 7th" (noted by just writing a "7" after the chord) or a "major 7th" added. Examples:
C = Cmaj7 or C7
F = Fmaj7 or F7
etc.
How do you know which one to use? In the end, you just have to go with what sounds best to you. But, if you had to pick a "rule of thumb", it would be:
"If the major chord is followed by a chord that is a perfect fifth lower, you can often make it a dominant 7th chord. Otherwise, try major 7th."
A perfect fifth is equivalent to seven frets. Here's the
circle of fifths--each chord is a fifth higher than the one below it (and a fifth lower than the one above it). Learn it, live it, love it:
C
F
Bb/A#
Eb/D#
Ab/G#
Db/C#
Gb/F#
B
E
A
D
G
...and back to C (that's why it's a circle!)
So, to use your example of G C Em D, and assuming it repeats, you'd have:
Gmaj7, Cmaj7, E-7, D7
Since the D is moving back to a G when you repeat the chords, and since the G is a fifth lower, you'd make that D a dominant seventh.
The C is moving to an E-, which not a fifth lower, so it's a major seventh.
The G? I guess that's an exception to the rule. Oops. Sure, it
is moving down a fifth to C. But your chords are actually in the
key of G. A major chord that's the same as the key the song is in will more often get a major 7th.
Hope that makes sense, and hope it helps!
JJ
P.S. In case you were wondering, there are chords beyond sevenths too. Ninths. Thirteenths. Etc. All give that "jazzy" sound. But start with the sevenths first.