Jocko's Jazz Banjo Page (or: relax, you can do this): Music theory for banjoheads, pt. 4, building 7th chords

You know G7, right? The full name is actually "G dominant 7th." Later for an explanation, but "a seventh chord," as understood here, is more of a generic term encompassing any 4-note chord built in thirds: Root, third, fifth and seventh.

In other words: Imaj7 - IIm7 - IIIm7 - IVmaj7 - V7 - VIm7 - VIIm7b5

Before going any further, practice your spelling on these chords. Remember, you presumably know already how to spell triads. Use this old knowledge to get to the new! So now figure out the spelling of:

Abmaj7

Ebmaj7

Fmaj7

Am7

Em7

Bm7

Db7

Bb7

Fm7b5

C#m7b5

Dm7b5

(answers at the end)

Knowing how 7th chords relate to each other in a particular scale is VERY IMPORTANT to a jazz improvisor. If you see a chord progression that goes...oh, say..

Cmaj7 - Fmaj7 - Em7 - Am7 - Dm7 - G7 - C

...one of the things you know you can do is play over the key of C-major. Those last three chords:

Dm7 - G7 - C

are the II, the V, and the I of the key of C, and collectively are called a "two-five-one." In many jazz tunes there are strings of two-five-ones like this:

F#m7 B7 Emaj7 Em7 A7 Dmaj7 Dm7 G7 Cmaj7

The first three chords are in E-major, the second three in D, and the last three are in C.

Here's a bebop tune with brackets drawn over the II - V - I's. We'll get into ways of playing these soon enough. Right now the thing is to realize that the three chords in a given bracket are all in the same key. (And don't worry about the melody, we're just focusing on the chord progression)

Sometimes a II-V doesn't make it to I. In musical terms, it doesn't resolve. Look at the bracketed pairs of chords in this tune by baritone sax player Gerry Mulligan:

Also notice bars 6 and 7, and the 3rd and 4th bars from the end: I - VI - II - V all in the key of G. But back to the unresolved II - V's in the brackets: can you figure out what key each is in? (answers at the end)(no peeking!)

Are you figuring out the secret code? "#5" means you raise the fifth, it doesn't necessarily mean you'll end up with a # in the resulting note. "Sharping" and "flatting" are also verbs. So when you see chords like C7#5b9, you'll know you raise the fifth and lower the ninth (the resulting chord will have the notes....)(yessssss????)

C E G# Bb Db.

Here is an F7 chord on the banjo in root position.

See if you can turn this into:

Fmaj7

Fm7

Fm7b5

Fdim7

F7#5

Fmaj7#5

Fm(maj7)

and while you're at it, find:

F6 (= a major triad + a Maj 6 interval from the root, FACD)

Fm6 (= a minor triad + a Maj 6 interval from the root, FAbCD)

Here are the different ways you'll see these written out on chord charts. Just below that is a diagram of triads and 7th chords in various minor scales. The main thing to remember is that a II - V in a minor key is generally expressed as IIm7b5 - V7 - Im.