*N.B* Prior theory knowledge will be extremely useful to get anything out of this article. A good understanding of chord/scale construction will be essential. That being said, this is what I believe to be a neat way of looking at the alterations of the dominant chord. It is not for the faint of heart. I hope you like the article and can take something useful away from it. Enjoy!
C13b9. C7#9. Caug7. C7b9#5. These are just a few examples of altered dominants. These chords typically resolve to a minor chord of some type, but are also commonly used to resolve to major chords as well. Try an unaltered C7, then a somehow altered C7 moving to F maj 7. Cool right? Assuming you are familiar with how a regular dominant 7th is constructed (1 3 5 b7), how do you arrive at altered dominants, and what should you play over them? The main goal of this article is to show the progression of alterations which lead' to the fully altered chord, and then the different combinations of tensions which are used together. I will use C as the root of the chord arbitrarily to show the different alterations, but will also make reference to numbers to help visualize and quantize it more efficiently to be used with any arbitrary root. I will layout the progression of alterations' first, then explain. I will deal with the extensions (9, 11, 13) as (2, 4, 6) in the scales, just know 2 = 9, 4 = 11, and 6 = 13 when you relate the tensions to the scales and vice versa. C is the root of all the scales.
Let us start with the manila dominant 7th chord, C7. First ask yourself: what are the most important notes in a 7th chord? If you answered the 3rd and the 7th, you would be correct. It is this tritone at the heart of the chord that wants to resolve in the plain dominant. That is why every scale here contains a M3 and m7 away from the root (with the exception of Dorian b2we will get there ;) ). When voicing these chords, always make sure you have the 3rd and 7th, unless you are wicked good with quartal voicings, which is a whole other topic altogether.
First though, we will explore each tension individually and how each voice leads to the nearest diatonic tones.
The b9 of the dominant is a half step away from both the 5th and 6th of the chord it resolves to. In the case of C7b9, the b9, Db, is a mere half step away from both C and D, so it would lead nicely to the D in either an F6 or F6/9 chord. It also leads conveniently to the 5th of F Major 7, otherwise known as C.
This tension lives between the 6th and 7th degree of the major scale/chord you are going to, or is conveniently the b7 of the minor 7th chord you are going to. So D# is either going to E in F major 7th or D in an F6 or F6/9. It could also be dropped to the D in a F-6 or F-6/9. It will simply be renamed Eb if we go to F-7 if you choose to hold the note over. Of course, you could also lead this tone to F since it is only a whole step away.
This tension lies right between the 1 and 2 of the resolution chord. So F# could resolve to the root of any F chord or to G if you want to play a 9th chord, here either F Major 9 or F-9. Try C7b9#4 going to F min/maj 9. Sounds sweet doesn't it?
This tone is the b3 of the next chord, so you can rest on it if going to F-7. However, you could also drop it a half step to become the 9th of the resolution chord, in our case G#/Ab to G of either a F maj 9 or F-9. This can also sneak up to A to become the third of any F major chord.
Now that every tension has been explored individually, here is the list of scales that can be played over dominants, from the most standard to most altered. Notice we get a #4, then additional b9 and #9, and then b5 and #5.
Mixolydian 1 2 3 4 5 6 b7
Lydian Dominant1 2 3 #4 5 6 b7
H-W Diminished (Octatonic) 1 b2 #2 3 #4 5 6 b7
FAltered Scale( Super Locrian) 1 b2 #2 3 #4 #5 b7
Other Scales outside progression:
Whole Tone1 2 3 #4 #5 b7
Mixolydian(b6)1 2 3 4 5 b6 b7
Phrygian Dominant1 b2 3 4 5 b6 b7
3rd mode of Harmonic Major (Phrygian b4?)1 b2 #2 3 5 b6 b7
5th mode of Harmonic Major (Mixolydian(b2))1 b2 3 4 5 6 b7
2nd mode of Melodic Minor (Dorian (b2)) 1 b2 #2 4 5 6 b7
So over a plain 7th chord, the most logical scale choice is Mixolydian, right? No alterations, nothing fancy. Just straight 1 2 3 4 5 6 b7. This works perfectly well over C7, C9, C13. You just might want to avoid landing on F though while the chord is ringing . It is where you are going, not where you are.
Whoa, what happened there? This is where the first alteration in the sequence comes into play. Let us assume an unaltered 5 here. Now we have a F# in our C7 chord, creating 2 tritones in the chord, one between C and F#, and the other between E and Bb. Sweet. How do we make sweet music over this chord? By using Lydian Dominant of course! Aptly named, it tells you exactly what is in the scale. Lydian tells you there is a #4, the Dominant gives you b7. In total you get a scale that looks like 1 2 3 #4 5 6 b7. This is the 4th mode of Melodic Minor. In our case, the Melodic Minor Scale that would coincide with C Lydian Dominant would be G Melodic Minor. Also try
Ok, let's think here. More than likely, we are headed straight for F-7 here. Let us assume we have an unaltered 5th here (G). The most common idea might be to play Phrygian Dominant here, which contains the same notes as Ab Harmonic Minor. Another option might be C H-W dim, or C Mixolydian(b2). Take your pick. If you see this chord symbol as an improviser, feel free to use really whatever you want, but make sure you have a Db in there.
This is the famous Hendrix' chord, although he was quite fond of E7#9. Same deal as before, use a scale that has a D# in it. You will commonly see the Altered Scale used here. Maybe even consider Dorian (b2). I posit use of this scale because it has both b9 and #9, and while it may not have a Major 3rd, you can always insert one.
Once again, Dorian (b2) and the H-W dim will work nicely. Also consider Mixolydian (b2). Use common sense (and the above chart to search for scales with both b2 and 6).
Whole Tone scale works nice over this one, which also throws a #11 into the mix. Try the Altered scale here as well, it is a good candidate to play over almost anything with a #5(b13)/b5(#11)
Consider Mixolydian (b6) among other things.
If you see this, throw in as many alterations as you can, making the Altered Scale an obvious choice. If you are familiar with tritone substitution, right there you are using the b9 and b5 of the altered dominant. Here is a powerful way to look at the Altered Scale: Imagine it is a major scale with a #1 a tritone away from the root of the resolution chord!
So for you smarty pants who might ask What happens if I tritone sub the altered dominant with an altered dominant? Funny you should ask. If you are leading to F major, it contains all the notes of F major except for F, which is replaced with F#. Major Scale #1 again!
That about wraps it up. In short, use your ears and brain when you play. There are several combinations of tensions which can be used together, so you can mix and match to your heart's content when dealing with altered dominants. Listed here are merely suggestions of scales to play over different chords, but remember, it is all about the melody!