A major 7
A - C# - E - G#
|This chord extension can be written several ways - Amaj7, AM7, or A∆7 with Amaj7 the most commonly used.|
|A Major Scale||A - B - C# - D - E - F# - G#|
|Chord Formula||1 - 3 - 5 - 7|
|Notes||A - C# - E - G#|
A major 7 Chords
e |-0-| B |-2-| G |-1-| D |-2-| A |---| E |---|
e |-4-| B |-5-| G |-6-| D |-7-| A |-0-| E |---|
e |--9-| B |--9-| G |--9-| D |-11-| A |-12-| E |(12)|
In the 3rd position, the chord is written (x/12)-12-11-999, while the notes are written (x/E) - A - C# - E - G# - E. This simply takes into account the optional note, which is the number/letter after the forward slash (/). We also separate any fret greater than 9 with a hyphen so as not to create confusion with double-digits, otherwise the chord above would be written (x/12)1211999... too confusing - which fret belongs to which string? etc.
You will find major 7 chords used often in jazz music and less in mainstream music, however when used cleverly, they can enhance a piece tremendously. The Amaj7 - 3rd position is a little difficult at first, but when you master it, what a sound!... if you can play it with the optional note, you are doing very well.
Standard keys using the A major 7 chord: A Major, E Major, F#m, and C#m. Each of the minor keys is the relative minor of the major keys, i.e., A/F#m, E/C#m. If you are playing songs in any of these keys, you may come across an Amaj7 chord.
Practice: If you want to practice playing a song with Amaj7 chords, you could try White Christmas. Although used sparsely, it still gives you an idea of how it can add warmth to the feel of the song.