Secondary Dominants?

I was trying to expand my knowledge on music theory, and found this doozy I thought a secondary dominant was the V(7) chord eg: in C Major, G(7) would be it? In the chart, I understand the Diatonic system, and though I don’t understand the theory behind the flat minor part, I understand it in practice. Could someone shed some light on it, please?

No, that’s the dominant, which is the fifth tone of the scale. In this context one might think of it as the primary dominant in contrast to the secondary dominants.

The secondary dominants apply to the 2nd, 3rd, 4th, 5th, and 6th degrees of the scale, representing what would be the 5th tone if one were actually in those keys. So the 2nd degree of a C scale is d; the 5th degree (dominant) of a D scale is a; therefore the secondary dominant of C’s 2nd tone is A. This is shown as V/ii (5th degree of 2nd tone) in the linked page, thus (in C):

2nd degree = d; 5th of D = a; V/ii = A

3rd degree = e; 5th of E = b; V/iii = B

4th degree = f; 5th of F = c; V/IV = C

5th degree = g; 5th of G = d; V/V = D

6th degree = a; 5th of A = e; V/vi = E

I will say that while I find that chart interesting, I think that a good working knowledge of the Circle of 5ths provides the same info in a form that’s easier to grasp and use (at least the way I teach it).

I think the first secondary dominant you need to learn is the V/V, i.e. the major II chord. It’s the most common out of them. Any time you have a phrase that ends on a V chord, try and see if you can put a V/V before it. And lots of phrases end in V chords (it even has a special name: a half cadence).

An obvious example that I’m sure everyone knows is Jingle Bells, which has the first part of the chorus ending on a V chord. Stick a V/V before it, and it sounds a lot better.

You also can often stick a secondary dominant anywhere where you are clearly following the circle of fifths, iii-vi-ii-V-I. If the song has any portion of it, try replacing one of the minor chords with a major version and see how it sounds. For example, if you have, say, C-Am-Dm-G, as a chord progression, try using A instead of of Am or D instead of Dm. Maybe even it A7 or D7. You can even do the minor followed by the major, or even use all three chords: e.g. C-Am-A-Dm-G or C-Am-Dm-D-D7-G.

Okay, I get secondary dominants now. Yes, I had mingled it in my mind with primary dominants >.> Both of you have explained it very well.

So… could someone explain the ‘‘flat minor’’ section of the linked chart?

Thank you for the kind words, glad to be of help.

Uh…what “flat minor” section? I see “diatonic system,” “flat majors,” and “secondary dominants.” I don’t see “flat minors.” Am I missing something?

It’s often easier to think of secondary dominants as the ‘5 of 5’. Really, it’s a temporary modulation to the key of the 5 chord, showing a 5-1 (where the 1 is really the 5 of the tonic key).


CHORDS:            G     D    C    G            A      D          G
Nashville #        1     5    4     1             2       5          1
RN Analysis        I     V    IV    I             II      V          I
Func Anal.  [G:]   I     V    IV    I     [D:]   V       I  [G:]  I


note: in the nashville number system, all chords are assumed Major unless notated otherwise.
As for the flat minor thing, I can guess you’re thinking of borrowed chords?
In minor keys, due to the multiplicity of minor scales (nat minor, harm min, mel min) there are multiple possible chord spellings at several scale degrees, and several new possible diatonic chords are introduced, including the bIII, the bVI and the bVII. Also the ii-7b5, III+ and VI+ but no need to go there in this post…

Yes, flat majors >.< I have not been sleeping much. Sorry.

Okay, the flat majors. I prefer looking at the circle of fifths to get this.

Note the roman numerals. In the linked illustration we have C as I, so we’ll use that. Note that any chosen key can be at I – for example if it were A, then IV would be D, V would be E, etc.

At the 12:00 (twelve o’clock), 11:00, and 1:00 positions we have the I, IV, and V chords used in the key of C: C, F, and G. These are the most commonly used chords in most genres of popular music – tons of folk, country, rock, blues, bluegrass, etc. songs use these extensively, sometimes exclusively.

At the 2:00, 3:00, and 4:00 positions we have D, A, and E, the II, VI, and III chords. These are also quite common. They include the typical minors in a given key (ii, vi, & iii, or as I prefer IIm, VIm, & IIIm), but are also often used as majors (II, VI, & III), most notably in what’s called a ragtime progression (I-III-VI-II-V-I). As majors they are shown in your diagram as the secondary dominants V/V, V/ii, and V/vi.

Those six positions {I, IV, V, II(m), VI(m), III(m)} cover 90+% of the chords used in most popular music.

Now at the 10:00, 9:00, and 8:00 positions we have the flat majors: Bb, Eb, and Ab. (I couldn’t find a diagram that showed the roman numerals for these, but they are bVII, bIII, and bVI respectively. That diagram has it written out as “flat 7,” “flat 3,” and “flat 6.”) These are less commonly used, but can be found in various songs here and there. For example, “Sweet Home Alabama” riffs through D, C, and G; these are the I-bVII-V chords for the key of D (NOT V-IV-I for the key of G – it’s in D). “To Know Him is to Love Him” uses I, V, VIm, & IV in the verse and then goes to bIII, bVII, & bVI in the bridge.

Your diagram also lists bII and bV (Db & Gb/F# in the key of C). This may be for completeness in theory, but in practice these are virtually never used other than maybe as brief passing chords in a walkdown. In my opinion, they can be safely ignored.

As to practical application, if you’re trying to figure out the chords for a song, first try I, IV, and V. Then look to IIm, VIm, and IIIm, followed by II, VI, and III. If that doesn’t do it, go to bVII, bIII, and bVI. There are a few other possibilities (diminished 7ths, IVm, etc.) but these will cover the vast majority of chords used in most songs.

Follow-up note:

In a minor key, the equivalent of a I-IV-V progression is Im-IVm-V, for example in A minor the chords would be Am, Dm, and E(7). Other common progressions use (some or all of) Im, bVII, bIII, bVI, and V, which in Am would be Am, G, C, F, and E(7).

The other extremely common minor progression is the ii-7b5 V7b9 i. It is analogous to the ii V7 I and the IV V7 I to a lesser degree.

Regarding “Flat Majors”…

As Gary T explained (so well)… these are rarely seen in Pop/Rock except for occasionally bVII.

However, if you like at scale notes instead of chords, these 3 flats are the famous “Blues Notes” -, and these are quick common in Rock.