Dominants and Subdominants
or: Can I alter this chord ? by Christiaan 'Niliov' van Hemert

This page deals with an issue a lot of beginning jazz-musicians wonder about: "How do you know when to alter a chord?". Actually this is a simple matter, but for some reason the explanation always seems long and difficult. If you've explored the other pages at The Jazz Resource Center you probably know I prefer practical explanations which may not always satisfy the "theory-purists" above complicated theoretical consistent explanations. I hope this page can keep up with that "motto".

Some Common Expressions

I want to start of this page with some common expressions you need to know in order to completely understand the contents of this page:


"7"-chord. For example: C7, D7, Ab7, F#7, etc.
(If you don't know anything about chord symbols first study:
Chord Symbols and What to Make of Them


The distance between two notes. Al the possible intervals have different names. These distances and according names are also mostly covered on Chord Symbols and What to Make of Them.


If you've come to this page you probably want to know about when to alter a dominant or when to treat it as a
"normal" dominant (I call normal: mixolydian#11). I feel however that it is also important to know that there are more possibilities besides altering a dominant. I call these possibilities colors. Here's my rendition of the different colors:

Colors : Extensions :
Mixolydian #11     9,13
Altered b9,b13
Octotonic b9,13
Wholetone 9,b13


This is very important!! Don't go on until you completely understand this section on the tritone.

A tritone is an interval of three whole tones. An other name for this interval is augmented fourth or diminished fifth. The curious thing about the tritone is that if you pile up tritone-intervals one after another you keep ending up with the same two notes. For example: C->F#->C->F#->etc. This "phenomenon" has some consequenses, especially for
dominants. Let's take a closer look at two dominants to clear things up: C7 and F#7. These two chords are "separated" by a tritone. We say: F#7 is the tritone-substitution for C7 and vice versa. Now, C7 consists of the following notes: C E G Bb and F#7 consists of:
F# A# C# E. Do you notice anything? Yes!! C7 and F#7 have two identical notes: E and Bb(A#). So the third of C7 is the seventh of F#7 and the seventh of C7 is the third of F#7!!! This of course is by no means a coincidence: the third and seventh of C7 and F#7 are as it happens "separated" by a....: TRITONE!!!

So far the theoretical stuff on the tritone. Now some practical things. You should remember the following properties of a dominant and its tritone-substitute (for example D7 and Ab7):
D7alt = Ab7mixolydian#11 (mixo#11)
Ab7alt = D7mixo#11

Note: For the purists: with the " = " between the chords above I mean that they have the same function.


In my book chord degrees are the same as chord functions. You can recognize both by the Roman numerals with which they are written. I bet you've heard of a "II-V-I" somewhere (pronounce: two-five-one). A full explanation of chord degrees can get get very, very complicated. And above all it's not important for this page (so it is important, but not for the subject this page is dealing with). I will confine myself to chord-degrees and their relation to dominants and subdominants.

There are two "sets" of chord-degrees:

Major Chord Degrees
Minor Chord Degrees

Major chord-degrees

Major chord-degrees apply to songs which are written in a major key. Let's assume we are dealing with a song in C-major. To derive the companion chord-degrees we look at the C-major scale:

Each note represents a degree:

If we apply the degrees to dominants we get:
C7 D7 E7 F7 G7 A7 B7

We get seven dominants; one for each degree. For example E7 is a dominant on the third degree, or a dominant on the III. I keep referring to a "7"-chord as a dominant. A dominant on V is called the dominant. The dominants on the other degrees are called sub-dominants. So: G7 is the dominant of C-major and C7 D7 E7 F7 A7 and B7 are sub-dominants of C-major.

Minor chord-degrees

Minor chord-degrees apply to songs which are written in a minor key. Everything I said in connection to
Major chord-degrees applies to minor chord-degrees as well. Only the scale we use to derive the degrees is different. We use the C-minor (harmonic) scale:
C D Eb F G Ab Bb C


If you've read the above you'll prabably think: "II-V-I ? I know what that is: in for example C-major that would be D7 - G7 - C7." Well, I'm afraid I'll have to dissapoint you! D7 - G7 - C7- are dominants on the according chord-degrees. "Officially" when you talk about a II-V-I you talk about the actual chords that go with that chord-degree. Before I get to thereoretical just remember the following: II without any further information means: a min.7-chord on that chord-degree. V actually does mean a dominant on that chord-degree and I stands for a maj.7- or 6-chord on that chord-degree. So in C-major a regular II-V-I would be: Dm7 - G7 - Cmaj.7/C6. Or a II-V-I in Ab-major: Bbm7 - Eb7 - Abmaj7/Ab6.

A II-V-I in minor is a bit different. I think two examples will be sufficient to understand a II-V-I in all minor keys.
C-minor: Dm7b5 - G7 - CmMaj.7/Cm6.
Ab-minor: Bbm7b5 - Eb7 - AbmMaj.7/Abm6

All right!! If you've taken the time to study the above you've come a long way. I think it's about time to explore the real reason you've started reading this page: "How the **** do I know when to alter a dominant ?" Before we start, let me make one thing very clear: "altered" is a "color" you can only apply to DOMINANTS (the same thing goes for the other "colors"). All too often I hear people talk about altering maj.7- and min.7- chords; there is no such thing!!!

To determine wether or not you can alter a dominant I have three "tricks". You'll see that it is quite easy to follow if you understand the common expressions I explained above. These "tricks" are to be used in the order I present them; that way most mistakes will be avoided. When you first start using this system I advice you to write the possibility to alter a certain dominant above the chord. This way it's easy to give a final check when you finished working on a set of changes (=sheet with chords for a certain song). Okay, here we go:

Looking for (II)-V-I's
Using chord-degrees
Looking for tritone-substitutions

Looking for (II)-V-I's

This is the first step. Carefully look through changes to spot all normal II-V-I's (minor and/or major) first. You can alter all V's here. You don't have to alter them, but you can; if it is a minor II-V-I it is probably a good idea to always alter the V.

Now look for all V-I's (without the II in front of them). You can also alter all these V's.

Finally look for II-V-I's with the II being a
dominant. For example: D7 - G7 - Cmaj.7/C6 or: Bb7 - Eb7 - AbmMaj7/Abm6. You can alter all V's; the dominant on the II however should be played as a normal dominant.

Make sure you get all the (II)-V-I's. You shouldn't worry about keys.

Using chord-degrees

Chances are you've already covered every dominant in your set of changes. If you still have some left use the following technique: determine if the left-over dominants are on a
chord-degree of the key the song is written in. Determine on which chord-degree. Now use the following list:

Dominant chord-degree : Color major : Color minor :
I Alt. (altered) An important exception being the I7 in a
major-blues: don't alter it.
II Mixo#11 Alt.
III Alt. Mixo#11
IV Mixo#11 Mixo#11
V Mixo#11/Alt. (altered is preferred by most musicians) Alt.
VI Alt (in "older" jazz mixo#11 is preferred) Mixo#11
VII Alt. Mixo#1

Don't fall in the "modulation-pitfall". Using this step it is important that you realise in which key to see the dominants. A song can be written in C-major, but the first four bars might as well be in B-minor. To determine the right keys in the right places it is probably best if you look for your (II)-V-I's, which you already have found with the first step. Mostly a (II)-V-I is the beginning of a modulation, every dominant that comes after this modulation until the next (II)-V-I is in the key of the I of the first modulation. This sounds a lot harder than it actually is (I know: a cliché), but things will be more clear when you study the example-song at the end of this page.

Looking for tritone-substitutions

Still have some dominants left? Probably not! If you do, you've chosen a hard song to begin with. No worries though, here's the third step: substitute all left-over dominants with the proper
tritone-substitutions. Now use step one and two again with the "new" dominants.

Well, that's it. It's that simple! f you still have dominants left I bet you made a mistake somewhere. Don't hesitate to ask me questions though. I will always answer E-mail.

Some Final Thoughts

You have to realise that nothing is foolproof. There are many exceptions to my "system". For example because the melody of the head dictates a certain color or just because "it doesn't sound right!". Therefore always check your outcomings at the piano; just listen and when something is bothering you (it is also always possible that you just aren't ready for the altered sound) change it!

When you first "discover" the altered color, you'll probably use it al l the time. I think most beginning musicians do; I did. Never forget though that there are other possibilities. octotonic and wholetone for example: you can almost always use these colors; taste is the rule here. Playing mixolydian#11 all the time is also possible. Or even playing altered when mixo#11 is theoretically the right choice. What I'm trying to say is: in the end nothing matters; when you play something that sounds great but is in theory "incorrect", who cares? Playing outside is also "incorrect" but can sound fantastic. So what's the point of learning the material written above? Well as my teacher told me and as I always tell my students: "You've gotta know what's "right" first to be able to play (convincingly) wrong!!".

SORRY!! I didn't have time yet to write the example-song. I will soon though, I promise!!

©1998 Christiaan 'Niliov' van Hemert. JRC.  JAZZ RESOURCE CENTER