II7, III7 & VI7 chords

Greg Vincent · From: Folsom, CA USA

Hi folks,

In a lot of popular music it seems like the minor chords of a given major key (the ii, iii & vi minor ) get thrown out and subbed with their non-diatonic, major cousins -usually dominant 7 versions (II7, III7, VI7). They sound really cool!

How come this works? And how come they're almost always dom7 versions? The non-dominant versions don't work nearly as well.

--Sleepless in L.A.

[This message was edited by Greg Vincent on 22 November 2004 at 11:54 AM.]

Jon Light · From: Saugerties, NY

Just on a wild guess that I'm talking about the same thing that you are talking about-------in some contexts, the dom7 chords you are talking about are actually V7 chords in a mini-modulation. So the II7 rather than the min7 implies a modulation to the key of V. In fact you could say that any time you deviate from diatonically correct chords you are modulating.

Or I could be all full of it.

BTW--I was watching Trio channel and in an end-of-the-hour time filler they played your video. I saw your Carter and then saw the band name and had to really dig deep in my mental mush to figure out where I had heard of the band.

P Gleespen · From: Toledo, OH USA

Sounds like we're talking about "secondary dominant" chords. Here's a web site with a not so bad description of 'em.
http://www.worldhistory.com/wiki/s/secondary-dominant.htm

Greg Vincent · From: Folsom, CA USA

Cool! Thanks guys. Secondary dominants --that makes sense. VI7 leads to II7 leads to V7 leads to I, and so forth. I like the term "mini-modulation".

I still don't understand how the III7 works though. It seems to always want to pull me to the IV chord, but it sure aint no dominant of IV!

I dig this stuff.

-GV

Jim Cohen · From: Philadelphia, PA

III7 usually "wants" to go to VI7. That's part of a standard jazz/pop turnaround that's 3-6-2-5 (back to 1), in which the 3 and 2 could be either dominant or minors, and the 6 and 5 are usually dominant (especially the 5).

In each case, you're going around the circle of 4th's. 3 to 6 is up a 4th, 6 to 2 is up a 4th, 2 to 5 is up a 4th, and 5 back to 1 is up a 4th. Your ear picks up the symmetry of that and (usually) likes it.

[This message was edited by Jim Cohen on 22 November 2004 at 03:46 PM.]

P Gleespen · From: Toledo, OH USA

Hey Greg, I was thinking about how you hear the III7 chord pulling you to the IV instead of the VI.

In the key of C, a III7 'd be E7 (E G# B D). That's pretty close to a Caug chord (C E G# ...and that D from the E7 chord'd work out as the 9th) which would definitely pull you to Fmaj.

Maybe that's what your hearing. Then again, maybe I'm wrong.

(I worked really hard to forget most of the theory stuff I learned in school, but sometimes I wish I could remember it... Just goes to show you: stay off the drugs, they'll rot your...what was I saying?

)

Gary C. Dygert · From: Frankfort, NY, USA

Ok, I get how C7 leads to F (of course) in the key of C & A7 leads to Dm, but I'm music-theory-challenged. Can somebody give an example, other than a Mozart piece, showing the simple chords and then them there fancy ones?

Steve Knight · From: NC

Hello,

The III pulling to the VI chord in the III-VI-II-V progression could also be looked at as two different II-V sequences in two different keys.

In other words, in C:

E-7(III) A7(VI) D-7(II) G7(V)

Could also be seen as:
E-7(II of "D") A7(V of "D")
D-7(II of "C") G7(V of "C")

I think that's why the VI chord is usually dominant. It's acting as a V chord in a II-V in another key. It makes the changes more interesting & implies a quick modulation to another key. The key of D, in this case.

Another cool dominant substitution is the flat-five substitute. I *think* it's also called the tritone substitute. You play the dominant chord that is a flat-five away from your original chord. In other words:

E-7 A7 D-7 G7 to C will become:

E-7 Eb7 D-7 Db7 to C.
Or
Bb7 A7 Ab7 G7 to C.

The last one I use often (and there are probably an infinite number of combos) is this variation on the I-VI-II-V.

C A-7 D-7 G7 to C
can become C7 Eb7 D7 Db7 to C(or C7.)

The reason why the tritone substitutes are dominant is because it's the only way to get it to sound correct. (At least to most ears.) When you sub one chord for it's flat-five substitue, the 3rd note in one chord becomes the dominant 7th note of the other chord. Also, the dominant 7th note of one chord becomes the 3rd note of the other chord.

For G7, the notes are G B D F. The flat-five is Db7. The notes of the Db7 chord are Db F Ab B(or "Cb.") You can see that the B & F notes are in both chords as the 3rd & 7th notes of both chords. Also, the remaining notes in both chords are just 1/2 step away from each other.

Sorry to ramble. Writing this out helps me make sense out of it, too.

SK

Greg Vincent · From: Folsom, CA USA

Great stuff, folks! -GV

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