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Im looking at this modal chord chart, and not really sure of the notation. What is s the difference between the 5 chord in the Ionian mode (V7) and the 5 chord of the Lydian (VM7)?

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  • Comment not an answer - just to point out that for the Ionian chords they can be generated from a normal major scale - you get them by playing 4 notes from a normal major scale where you play a note and miss a note - e.g in C ... IM7 = CEGB - then IIM-7 = DFAC etc. each time you play one note then skip the next note and play a total of 4 notes. If you start on the root (e.g. C) you get the I chord, start on the next note of the scale (e.g.D ) and you get the II chord etc.
    – tom
    Jan 16, 2020 at 16:34
  • As you can see from the answers below a major 7th chord on V can be written either as Vmaj7 or VM7. I would include that you could also write V♯7. Mar 21, 2021 at 22:56

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That chart seems to be using a jazz chord convention mixed with Roman numerals for roots on scale degrees.

In that system:

  • plain 7 means dominant seventh chord where the triad is major and the seventh is understood to be a minor seventh.
  • -7 or m7 means minor seventh chord where the triad is minor and the seventh is minor.
  • M7 means major seventh chord where the triad is major and the seventh is major.

It's not clear just from that chart, but the convention is M in M7 is major in reference to the seventh.

It's not part of the diatonic seventh chords of the chart but something like CminM7 is a common symbol. That's a minor major seventh chord. Parenthesis Cmin(M7) can make it clearer the M is for the seventh.

When you see - or lowercase m it a modification for the triad. C- or Cm meaning C minor triad.

Finally, getting back around to V7 we see there are none of the modifiers -, m, or M, but we understand the seventh is minor in a dominant seventh chord. There we can see that plain 7 in jazz chord symbols is a minor seventh above the root by default.

FWIW dim7 is used for fully diminished seventh chords, and m7(b5), -7b5, etc. is the jazz chord way to say half diminished seventh chord.

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    Your penultimate sentence is correct (of course!) but could be misconstrued as minor seventh chord. I'm certain it's minor seventh as an interval within the chord, but it's ambiguous - to some, I guess!
    – Tim
    Jan 16, 2020 at 7:50
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    @Tim, I made a little edit to line I think you meant... Jan 16, 2020 at 13:35
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To understand the determining factors that constitute what is a V7 chord and what is a VM7 chord, we need to look at the step patterns, half step and whole step, of each individual mode. Because the step patterns are different for each different mode, the major and minor intervals are rearranged within each mode. Looking at the Ionian mode we see the interval between the root or tonic of the mode, and the seventh is a minor interval and is abbreviated as V7. Next we look at the Lydian mode and discover that the interval between the root and the seventh has an extra half step space between the root and the seventh causing it to be a major interval and it is therefore abbreviated as a VM7. The main thing to understand is the V7 has a minor seventh interval and the VM7 has a major seventh interval.

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Let's look at modes from a parent key perspective. You ask about Ionian V and Lydian V. In C Ionian, (taking its notes from key C major) the V consists of G B D F. C Lydian V (taking its notes from parent key G) is G B D F♯. Difference between both is the F note.

In the first, the chord is named G7, a dominant chord in that key. The base triad is a simple major one, but the 7th note itself forms the interval of m7. This is probably the most common of all the 'sevenths', and its name gets shortened to mere '7th'.

Because of the raised note in Lydian, compared with Ionian, C Lydian V has an interval of M7 instead, (G>F♯) making the chord called 'major 7th or M7' - with the same base triad underneath.

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Naming some of the chords like "bIII" in the Dorian mode seems pointlessly confusing.

The third degree is the Dorian mode IS "flat", compared with a major scale (or the Ionian if you like fancy terminology.) It doesn't need to be made more flat!

Similarly for "#IV" in the Lydian mode, etc.

The whole "modal chord" concept in Jazz is an incoherent mess, IMHO.

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If your trained by moveable do you will understand this explanation:

Ionian: I=do and V=so

Lydian: I=fa and V=do

V7 Ionian = so,ti,re,fa (so-fa = minor 7) in the system of classical harmony this is a Dominant 7, with tension to resolve to do,mi,so.

V7 Lydian = do,mi,so,ti (do-ti = major 7) identical with the tonic Major 7 of the Ionian 7 and is rather a stable chord in the classical jazz harmony.

It is important to know that minor and major referring intervals will mean that they are large (major) or small (minor).

(A major 3rd, 6th or 7th is a semitone „larger“ than a minor ... so don‘t confuse here the terms with the modes or keys.

https://en.wikipedia.org/wiki/Major_and_minor

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