types of 7th chords

[Darren]

Hi everyone,

was just wondering how many types of 7th chords there are and if there are different ways in which the same chords are written.... as is often the case in this confusing world of music theory (i know they do it on purpose!)
could anyone explain what the difference is between Amaj7, Adom7 and A7. have i missed any?
also, what is the tonality of each? maj/min :confused:

thanks in advance to anyone who can spare the time :)

[Poparad]

Amaj7 - R 3 5 7
A7 - R 3 5 b7
Am7 - R b3 5 b7
Am7b5/AØ7 - R b3 b5 b7
A°7 - R b3 b5 bb7
Am-maj7 - R b3 5 7


Amaj7 - A C# E G#
A7 - A C# E G
Am7 - A C E G
Am7b5/AØ7 - A C Eb G
A°7 - A C Eb Gb
Am-maj7 - A C E G#


If the first three notes are a major triad (1 3 5), then the tonality is major. Minor (1 b3 5), then minor. Diminished (1 b3 b5), then diminished.

[UKRuss]

Well 7th chords are four note chords made up of root, 3rd, 5th and 7th.

While the root remains the root, say C, the other notes can vary and thus change the make up and name of the chord.

Scale of C major

C D E F G A B

Chord of Cmajor C E G (1,3,5)
Chord of Cmajor7 C E G B (1,3,5,7)
Chord of C7 C E G Bb (1,3,5,b7)
Chord of Cmin7 C Eb G Bb (1,b3,5,b7)
Chord of Cmin7b5 C Eb GB Bb (1,b3,b5,b7)
Chord of Cdim7 C Eb Gb Bbb (1,b3,b5,o7)

Check out Guni's articles here for some more insight into chord construction and voicings.

[UKRuss]

Double bubble!:D

[Darren]

wow! thanks guys, better responses than i could have imagined. it's all so clear to me now.
would i be right in thinking that the 7 chord which is usually found in 12 bar blues is more often than not, the R 3 5 b7 ?

[Poparad]

wow! thanks guys, better responses than i could have imagined. it's all so clear to me now.
would i be right in thinking that the 7 chord which is usually found in 12 bar blues is more often than not, the R 3 5 b7 ?

Yes.