Using standard Roman numeral analysis how should 7th and 9th qualities be determined?

Question

Example:

C: V7 or inversions like C: V6/5 are understood to be dominant-seventh chords and C: V9 a dominant ninth chord with a diatonic, major ninth.

I think the basic idea is all the Arabic numeral parts are understood to be diatonic relative to the root indicated by the Roman numeral.

V9 in C major the root of V is G and the 9th above that root is A which is a major ninth.

By comparison iii9 in C major the root of iii is E and the 9th above that root is F which is a minor ninth.

That seems clear enough, but what about when the Roman numeral symbol indicates a chromatic chord?

Examples:

C: V9/ii or Am: I7 or C: iv9

When secondary or borrowed symbols are used I understand that we are temporarily referencing a new tonic/key and I sort of expect the Arabic numerals should then be relative to the temporarily referenced tonic/key.

If that is way it should be done, I get these examples...

C: V9/ii is a secondary dominant relative to tonic/key Dm and V9 in Dm would get a minor-ninth. So the chord C: V9/ii is A C# E G Bb.

Am: I7 is a borrowed chord relative to parallel major A major and I7 in A would get a major-seventh. So the chord Am: I7 is A C# E G#.

C: iv9 is a borrowed chord relative to parallel minor Cm and iv9 in Cm would get a major-ninth. So the chord C: iv9 is F Ab C Eb G.

I think the confusion is when using secondary or borrowed chord the RNA symbol isn't relative to the key denoted by the colon C: , Am:, etc. but by the secondary slash or switching of upper/lower case which indicates a temporary tonic/key or mode change from the key denoted by the colon.

...is this correct?

Answer 1

There are multiple variants of RNA in common use. The distinguishing styles V, v, V⁺, v° will be readily recognized as symbols for major, minor, augmented, and diminished triads over a root that is a diatonic scale degree (for a chromatic root, a prefixed accidental must be used, as ♭II⁶ for the Neapolitan sixth).

However, there seems to be no similarly standard convention for distinguishing qualities of 7th and 9th chords, apart from vii°⁷ and vii^ø7 for diminished and half-diminished 7th chords respectively. The most sensible convention is to style the Roman numeral according to the quality of the underlying triad and assume the added notes are diatonic unless indicated otherwise, for instance

• C: iii⁹ is E-G-B-D-F (= Em^7♭9 in jazz notation)
• C: V⁹/ii is diatonic in the key of ii, i.e. A-C♯-E-G-B♭
• C: I⁷ (or I^M7, etc.) is a major seventh chord; C: I^♭7 or I^dom7 is a dominant seventh chord (a.k.a. V⁷/IV, but with different functional implications)
• C: iv⁹ is F-A♭-C-E-G, a perfectly normal mixed-mode chord.

In minor keys the picture is muddied by the presence of multiple variants of the 6th and 7th scale degrees. Unfortunately for the standardization-minded, a: VII (G-B-D) and a: vii° (G♯-B-D) are in common use. Musically, 7ths and 9ths of chords tend to be drawn from the natural minor scale because they typically resolve downward. Therefore, I'd interpret a: i⁷ as a minor seventh (common in sequences) unless clearly written otherwise, e.g. a: i_♯7⁹ (sorry I can't make the numerals vertically aligned).

Answer 2

I assume this question is developed from recent questions concerning accidentals whether they are chromatic or diatonic.

It is a question concerning analysis and different analysis systems : RNA and analysis of Jazz/Pop.

In Jazz - and the Riemann/Maler system would be no confusion while in the RNA you have to decide for modulation or not. If your analysis is continuing in the new key the (V7) are minor 7th and (V9) are minor when they are secondary dominants to ii,iii and vi degree.

If your not changing the key in your analysis there will be no confusion by adding a small flat in front of the 7 in case of I becomes a secondary dominant to IV (as in Jazz the V7b5).