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What is the difference between a G7 and a G major seven chord? I assumed that a G chord with a seven behind it would be a G major seven. Could somebody explain to me the difference and how they are typically written?
I.e. what is the difference between a G7 and a GM7 guitar chord?
The difference is the kind of 7 you use. A "regular" G7 (also called a "dominant seventh" chord) is a G-major chord with the minor seventh added, so it's G B D F. A "Gmaj7" or "GM7" is a G-major chord with the major seventh added, so it's G B D F#.
(For the sake of completeness, Gm7, or "G minor seventh", is a G-minor with a minor seventh, G Bb D F, and GmM7, or "G minor/major 7th", is a G-minor with a major seventh, G Bb D F#.)
There is a naming convention for chords.
G = G major, or X = X major where X = any note, the triad is (1, 3, 5)
G- = G minor, or X- = X minor for any note X, triad = (1, b3, 5)
When it comes to 7ths just a '7' indicates a dominant 7th chord and that has a flat 7th.
G7 = G dominant 7th = (1, 3, 5, b7) = (G, B, D, F), this is the V ("five") chord in the Key of C major
A major 7th is indicted with "Maj"
G Maj7 = G major 7th = (1, 3, 5, 7) = (G, B, D, F#)
Consequently a minor seventh is the minor triad with a flat 7th on top.
G-7 = G minor 7th = (1, b3, 5, b7) = (G, Bb, D, F).
As for voicing you can arrange the notes any way you like and double up notes.
Both have the basic G major triad as a base. G, B and D.
Since G7 (G dominant seventh) is the most commonly used 7th chord, it is called by its friends simply G7. It's diatonic in key C major, and has the addition of F♮.
GM7 (G major seventh) has the addition of F♯ instead of F - the major seventh note in key G major. Thus it's a G major triad with the major seventh note added. It's diatonic in key G major.
As far as guitar chords are concerned, generally, there will be at least one of each of those notes quoted in each chord. For an open version of G7, it's 320001, or 323001 or 323003 or 323033. That's not exhaustive!.
For GM7, the usual is 320002.
G7 is shorthand for G dominant 7 chord. GM7 would be for your G major 7. Gm7 for G minor 7.
Most chord labels are shorter if the chord is more widely used. There's only a general preference for major.
You can see most here on my site: https://pianocheetah.app/practice/chords.html
(if a mod wants to copy that directly onto stackexchange, I'm cool with that)
Harmony:
G maj7 (GBDF#) is a stable chord and can be used as a tonic or subdominant. (In classical music it is very seldom as tonic, but as IV7 in the key of D it is quite usual).
G7 (GBDF) has a tension for resolving to C (CEGC) - (because of the tritone F-B) and has a dominant function, this means it is functional quite different from G maj7. This theory is applied in common practice period and in pop and jazz while in blues all chords and all degrees are usually seventh chords - minor 7th!
Dissonance:
You can also hear the difference of the interval of the minor 7th and major seventh: the dissonance of the G maj7 is sharper as it contains the minor second F#-G to the upper octave or in its 3rd inversion. F#GBD.
The difference is in the size of the seventh interval: either major or minor.
A major seventh chord has a major seventh above the root.
A dominant seventh chord has a minor seventh above the root.
The exact spelling of the tone of the seventh above the root using sharps/flats will depend on the placement of the chord in the key.
The seventh chord built on the tonic is a major seventh chord.
The seventh chord built on the dominant is a dominant seventh chord.
You can call those diatonic seventh chords, they don't require accidentals and just take the notes of the key signature.
You can build any type of seventh chord on any scale degree, but if they aren't diatonic, you call them chromatic.
It's easier to show with notation...
...green highlights the diatonic chord, yellow chromatic examples. Notice the sharps and flats of the key signatures and how accidentals must be added only to the chromatic chords.
G7 - a dominant seventh chord - in the key of G major will indeed require an accidental, but not a flat. It will require a natural on the F. It's common to call it a "flat seventh", or something like that, but properly speaking it's a lowered seventh, lowered from the key signature.
Oct 8, 2020 at 16:34
G7 in G major is chromatic, tonicizing or modulating to C major. In jazz or rock could say it has a modal flavor, from the mixolydian mode, or you might say the tonality isn't in the strictest sense the 'major/minor system.' Things get nit-picky and confusing when classical and jazz theory are commingled.
Oct 8, 2020 at 16:35
First off, don't look for any deep logic behind the naming of these chords. We can argue all night over what G7 and Gmaj7 SHOULD mean. But I can tell you what they DO mean
G7 is a G major triad with the minor 7th added. G, B, D, F. Gmaj7 is a G major triad with the major 7th added. G, B, D, F♯.
If you want to go on:
Gm7 is a G minor triad with the minor 7th added. G, B♭, D, F. Gm(maj7) is a G minor triad with the major 7th added. G, B♭, D, F♯.
Gaug7 is a G augmented triad with the minor 7th added. G, B, D♯, F. Gaug(maj7) is a G augmented triad with the major 7th added. G, B, D♯, F♯.
And, just to break the pattern of logic: Gdim7 is a G diminished triad with the DIMINISHED 7th added. G, B♭, D♭, F♭. And the version of this with a minor 7th isn't called 'Gdim anything', it's Gm7(♭5) which is G, B♭, D♭, F. (OK, it's also sometimes called G half-dim.) There's also Gdim(maj7) which is G, B♭, D♭, F♯.
See? Don't look for WHY, just learn HOW. (And I hope I got all of those right :-) )
What’s the difference between a G7 and a G major seven chord?
You have made an error which may be adding to your confusion. You should write and say G major seventh.
The word major does not apply to the G, it applies to the seventh.
You may be thinking G major (seventh). Instead you should think G (major seventh). In other words it is an ordinary G chord with a major seventh added to it.
Here are some chords (note that they can be written differently - jazz chords aren't usually written the same as in pop music)
G - G major chord - G B D
Gm - G minor chord - G Bb D
G7 - G major chord with a flattened 7th added - G B D F
Gm7 - G minor chord with a flattened 7th added - G Bb D F
G maj7 - G major chord with a major 7th added - G B D F#
Gm maj7 - G minor chord with a major seventh added - G Bb D F#
EDIT
As pointed out in a comment below by @Tim, the writing of chords is not entirely consistent. It's just something you get used to. Feel free to ask again if there are other confusions!
dominant seventh (G7) is the major chord with an added seventh minor, and it's an approximation of the harmonics 4 (C),5 (E),6 (G),7 (A sharp) centered in C. The A sharp is in reality quite distant from the seventh harmonic, but that's a compromise of using a 12 notes system. major seventh (Gmaj7) is the major chord with an added seventh major (CEGB). It's an almost exact approximation of the harmonics 6 (C), 9 (E), 12 (G), 15 (B) centered in F.
