[Noodler]

What is at about a Chord that makes it Dominant?

eg in the Nashville system, the IV is called the sub-dominant, and the V chord is called the dominant chord of the key.

We also have "dominant" 7th chords, spelled 1,3,5,b7, as opposed to major 7th chords (1,3,5,7).

The V is often a V7, but I'm pretty sure that a III7 is still a dominant 7th, too, isn't it?


The reason I ask is that in Tritone Substution you can substitute a dominant chord for another chord a Tritone away hence the name. So instead of playing Gmaj7, Amin7, D7, back to G, you could play Gmaj7, A min7, G#7, G. (G#7 has substituted for D7).

So does that mean you can substitute any dominant 7th chord, or just any V chord?

Thanks in advance.

[Fretsource]

Hi Noodler
The Dominant is the 5th scale degree of major and minor scales. I didn't know the Nashville system used those terms too - I've learned something.
Anyway the 7 notes (scale degrees) are named TONIC, SUPERTONIC, MEDIANT, SUBDOMINANT, DOMINANT, SUB MEDIANT and LEADING TONE.
As you know, you can build chords on every scale note. The chords take the same name as the scale degree that they're built on so the one built on the DOMINANT scale degree (the V chord) is called the DOMINANT CHORD - if it's a 7th chord, then it's called THE DOMINANT 7th chord.
Originally, the term DOMINANT or DOMINANT 7th referred only to that chord IF it was the V or V7 chord - but things change and now the term is used for that type of seventh chord (1 3 5 b7) no matter what scale degree it's built on.
What makes this chord unique and worthy of the name DOMINANT is that it's the only one that contains a TRITONE that wants to resolve strongly to the TONIC or I chord. That chord alone defines the key.

But a TRITONE can actually resove two different ways and that's what allows you to substitute.
In the key of C major the tritone is B - F (in the V7 chord G7) - it resolves naturally to the tonic chord C major
In the key of Gb major the tritone is F - Cb (= B) (in the V7 chord Db7) It resolves naturally to its tonic chord Gb major
The two tritones sound the same as they have the same notes (although named differently to conform with their keys) and that's why you can substitute one for the other.

[bmurnahan]

So does that mean you can substitute any dominant 7th chord, or just any V chord?

Hi Noodler,

The answer is yes, you can do a b5 sub on any dominant 7th chord, not just the five chord.

Also, since the pull of the dominant is so strong in a V to I manner, it's common to sub dominant 7th chords for minor chords in a progression.

Your I vi ii V example could become

Gmaj7 E7 A7 D7

Using b5 subs you would get Gmaj7 Bb7 A7 Ab7.

Using b5 subs creates nice chromatic motion in the bass line.

You could also play Gmaj7 E7 Eb7 D7 or any combination of those chords. If you are creating a chord melody arrangement the melody of the song will play a big part in determining which chords to sub and when.

The melody will also determine the quality of the chords. When substituting chords you don't necessarily have to just use dominant chords.

Bob

[Fretsource]

Just a quick correction to my post. The Dominant 7th isn't the only one containing the tritone - The vii dim and m7b5 chords have it too.

[Rockerbob]

Whips & Leather?

[allthumbs]

Any chord that is bigger than me!!

[Noodler]

Originally Posted by Rockerbob

Whips & Leather?

It took me a minute to get that!

Hope I referred to the Nashville system correctly. I just meant building chords on the scale degrees and giving them the names I, II, III, etc.

Fretsource, as you say, when you substitute for the V chord, you have two notes in common anyway, and that's as far as I've actually experimented with it so far.

bmurnahan, that is one of those posts that is so awesome, I'm just going to have to mull it over. It is exactly what I was after.

Using b5 subs you would get Gmaj7 Bb7 A7 Ab7.

Using b5 subs creates nice chromatic motion in the bass line.

That's how I have seen it used. A guy goes to me, "You'll have to learn to use tritone substitution" and starts playing a chromatic chord thing, one beat to each chord. I just couldn't see how you got from what Fretsource was saying, to that! I still don't get it, but I imagine after playing through and thinking about the progressions you've written, it'll be clearer. I love the chromatic bassline thing.

When you are making those subs, are you actually thinking about notes in common, or just that you can slip in a chord a b5 away? ie is it something you do on the fly while accompanying, or do you sit down and work it out?

I'm going to print that post out and mull over it and play the examples. Awesome!

[bmurnahan]

Hi Noodler,

When you are making those subs, are you actually thinking about notes in common, or just that you can slip in a chord a b5 away? ie is it something you do on the fly while accompanying, or do you sit down and work it out?

I don't think about the notes in common. You can just slip in a chord that's a b5 away. I personally believe that it takes time in your practicing to work these things out and when they become part of your vocabulary, you can do them in a more spontaneous manner.

I really don't know of anyone that just magically starts to do these kinds of things without practice and experience.

Also remember that the chord symbols (A7, Ab7) etc are just general. You can add alterations and extensions as you choose. Here are a couple of my favorite devices.

Common tone on top.


Bb9 Ami11 Ab7b5 Gma7
----x------x------x------x-----------------------
----3------3------3------3-----------------------
----5------5------5------4-----------------------
----6------5------4------4-----------------------
----x------x------x------x-----------------------
----6------5------4------3-----------------------



Bb7#5 A13 Ab7 Gmaj7

----x------x------x------x-----------------------
----7------7------7------7-----------------------
----7------6------5------4-----------------------
----6------5------4------x-----------------------
----x------x------x------5-----------------------
----6------5------4------3-----------------------


Chromatic movement on top

Bb7 Amin7 Ab7 Gmaj7

----x------x------x------x-----------------------
----6------5------4------3-----------------------
----7------5------5------4-----------------------
----6------5------4------4-----------------------
----x------x------x------x-----------------------
----6------5------4------3-----------------------


E7b9 Amin7 D7b9 Gmaj7

----x------x------x------x-----------------------
----6------5------4------3-----------------------
----7------5------5------4-----------------------
----6------5------4------4-----------------------
----7------x------5------x-----------------------
----x------5------x------3-----------------------

This last does not use the b5 sub but you get the idea.

Bob

[Noodler]

Excellent. Between the 3rd and 5th fret of that Bb9 is a stretch for me. I was way slow at changing chords, but can hear what you're driving at and it sounds nice and smooth. Some nice inversions I've never tried there.

I'd like to add this, which was posted a while ago, by Monk. I saved it and then forgot it till yesterday:

Tonic=Home Base or Rest
Sub-Dominant moves away from Tonic
Dominant returns to Tonic

All of the seven diatonic chords break down into one of these three main functional categories.

The Tonic chords are I, iii and vi.
The Sub-Dominant chords are IV and ii.
The Dominant Chords are V and vii.

The reduction of seven chords into three categories is made possible by the common tones shared by the chords each category. This also makes diatonic substitution possible.

How's that for a gold nugget!