someone asked this question:
>If in a major key the chords move like this:
>Maj7-mi7-mi7-Maj7-dom7-mi7-mi7b5, (not including the extensions 9ths, 11ths,
>13ths etc.), where do you fit in the altered chords? Pretty vague I know.
>I understand when you start blending other scales (Harm. minor, Mel. Minor
>things are going to change. Would somebody mind making a list of chords, as I
>did for the major scale, that include the altered chords?
> Hope this makes sense.
and here was my answer:
that's not really the way it works; there isn't really a convenient diatonic "altered" harmonized scale that all "altered" chords come from. First of all, the term "altered" is a little vague; it means different things to different people. I think it would be safe to say that a basic generic definition of the term might be something like "altered chord; a chord where one or more of the tones is altered from what they would natrually be in the current key center."
So with your above example, let's say in the key of C, any chord that used a note other than C, D, E, F, G, A, B would be considered "altered." Probably the most common type of chords in jazz that tend to be altered are dominant seventh chords. Usually, adding "altered" notes from outside the key center gives an increased sound of dissonance, which works well with the dominant since this sound usually functions as a dissonance that gets resolved anyway. So adding altered notes increases the tension, making the resolution that much more satisfying.
Typically, you wouldn't alter the fundamental chord tones of Root, 3rd or 7th; this would make the chord sound like something else other than a dominant chord. So the notes that tend to get altered are the upper extensions, plus the 5th. It just so happens that there are two scales, the so called "altered scale" (which is the seventh mode of melodic minor), and the half whole diminished scale, that contain all essential notes of a dom.7 chord, plus many of the possible altered upper extensions. In C again, this would be;
G, Ab, A#/Bb, B, C#, Eb, F
This contains the basic essential chord tones of G7;
plus the upper extensions of;
Notice that there are some enharmonic equivalents here; the A# is the same note as Bb, the b3 of G. A b3 on a major chord tends to sound like a "blue note." Also, the C# is the same note as Db, the b5 of G, and the Eb is the same note as D#, the #5 of G. So any combination of these notes would "jibe" with the altered scale.
Note also that the notes in the G altered scale are the same as the notes in the Ab melodic minor scale, so as a shortcut to getting your feet wet with this sound you could think "melodic minor up a half step" when soloing or comping over a V chord.
On to the G half whole diminished scale;
G, Ab, A#, B, C#, D, E, F
here we have all 4 chord tones of G7;
plus the upper extensions of;
Notice that there are a lot of similarities between the altered scale sound and the half whole diminished sound. The most obvious difference is that the h-wh diminished has a natural rather than a flatted 13th. The natural 13th gives what could be described as a slightly "brighter" sound. Either of the two sounds work nicely for increasing the tension in anticipation of a resolution back to the I chord, though.
Of course, normally in the major scale there is only one dominant 7th chord, the V chord. Another concept that comes up quite a bit in jazz (and other types of music as well) is that of the secondary dominant. Any major (including the dominant V chord) or minor chord in the key can be preceded by a chord that is the V chord of THAT chord. For example, in C major, the II chord is Dm7. Normally in D major or minor, the V chord is A7. Adding an A7 chord before a Dm7 can increase the tension and the sound of needing to resolve to the Dm7 chord;
| Cmaj7 | | Dm7 | G7 | Cmaj7 |
with secondary dominant of II:
| Cmaj7 | A7 | Dm7 | G7 | Cmaj7 |
To further increase the tension, altered tones could be added to the A7 chord, and these sounds could be thought of as coming from the A altered or A half whole diminished scales.
Note that there are also other scales which contain some of the altered notes, but the altered scale and half whole diminished scale are probably the most common to be associated with V chords and secondary dominants. Also, it's a good idea for beginning to intermediate improvisors to become comfortable with improvising with the basic chord tones before getting too deeply into altered harmony and substitute scales, like the altered and diminished.
Lastly, chords other than the dominant can certainly be altered, and often are. Some other common alterations (again, in the key of C) would be;
#11 on the I chord (Cmaj7#11). This could be thought of as a sound borrowed from the key of G (all natural notes + an F# is the key of G)
b5 on the II chord (Dm7b5). This could be thought of as a borrowed sound from the key of C minor. C natural minor will work, as will F melodic minor, which has all 4 chord tones plus upper extensions of 9, 11, and b13.
b3 on the IV chord; this fundamentally changes the sound of the IV chord from major to minor, of course, but creates a nice pull back to the I chord since Ab and F (the b3 and root of Fminor) are a half step away respectively from G and E (5th and 3rd of C major). Many scales are possible, but one that produces many common tones with C major is F melodic minor. This will yield an Fminor triad with a natural 7, 9, 11, and 13 (the only notes different from C major will be the b3, Ab, and the 11th, Bb.)
Note; a common substitute for the IV minor sound is the bVII dominant sound. If you take the F melodic minor scale, start from Bb (the 4th degree), and harmonize in thirds, you end up with;
This is usually referred to as the "lydian dominant" sound. Very often in standards you'll see this chord used in place of a minor IV;
| Fmaj7 | Fm | Cmaj7 |
| Fmaj7 | Bb7 | Cmaj7 |
In this case, the F melodic minor scale forms the basic sound of the second chord, but in the second case a different root movement gives a slightly different flavor to the progression. In either case the soloist could use the F melodic minor scale and get the same effect.
These are some of the more common "alterations" of diatonic major scale harmony. There are lots of other possibilities, but I hope this helps at least scratch the surface of answering your question.
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