There are only three Major Scales, and the onlt differences between them involve the 4th and 5th degrees. If you look at them this way, it allows you to realize that they are more similar than different. Which scale you use is then dictated by your taste and what the tune or style of music calls for.
The most common Major Scale is also known as the Ionian Mode (why are we speaking Greek?). It looks like this:
This is the scale most closely associated with a Major 7 chord and it’s relatives, Maj 6, Maj 9, Maj 6/9, etc. Use this Major Scale over Major chords when playing in strongly key oriented tunes such as Rhythm Changes and whenever the chord progression resolves stongly to a Major chord. With this scale, the 4th degree is not usable a s a point of rest or emphasis because it makes babies cry and will annoy your fellow musicians if you play it. Really.
To get around this problem, raise the 4th degree by a half step, which is known as the Lydian Mode (thanks Lydia, whoever you are). It looks like this:
The 4th degree can now be used as a point of rest. This scale is closely associated with the Maj7#4, Maj7#11, Maj7+4, etc chords. Some folks write it as flat 5, which to me is misleading, since the scale has a natural 5. Hey, a guy (or gal) can rant every once in a while.
The Maj7+4 Scale is more commonly used when the Major Chord (including plain old Maj7) lasts longer than say, one measure (unless the tempo is slow). You might not use it as much on Rhythm Changes as you would on a Wayne Shorter or Joe Henderson tune. A good way to get the Lydian sound is to outline the major triad built on the second degree of the scale.
After raisng the 4th degree, the only other alteration that is associated with a commonly used chord symbol is to raise the 5th degree, known as Lydian Augmented (this is the third mode of the Melodic Minor Scale, pass it on). It looks like this:
This Major Scale is associated with the Maj#5 chord. This symbol is not as common as the previous two Major Chords, and practically never appears in tunes written before 1960. This scale is an option when playing over regular Maj7 chords if the style is appropriate. If you are playing with folks who are deeply into the Bebop tradition, this might not be the first choice. If a more modern style is happening, you can put the raised 5th to good use.
As with any musical structure, idea or device, let your ears be your guide. The guidelines above are for general purposes, and you will hopefully find exceptions to anything that is rule-like. You might even be the cat who makes it hip to play natural 4 against a Major Chord!
There are five Minor Scales, three of which define commonly used chord symbols. The way in which they are different is in the treatment of the 6th and 7th degrees, except for the last one. Degrees 1-5 are the same for three of these scales. Which means they are more similar than different.
The most used minor scale is the Dorian Mode, which has a natural 6th and a flat 7th. This is the sound that best defines a Minor 7 chord, Minor 6, Minor 9, etc., and is the “default” scale choice for any minor chord that doesn’t specify something else. It is the ii-7 in a ii-7 V7 I chord progression, and is also the most used scale when playing in a modal situation. It’s important to be on good speaking terms with this mode. Here it is:
If you raise the 7th of a Dorian Mode, you get a Minor Maj 7 Scale, also known as Melodic Minor. This is the scale that defines a Minor Maj7 chord. The natural 7 is a useful color over other minor chords, and is traditiinally used as the tonic in minor key tunes. Trane would often use it in a modal tune (such as Impressions) after first establishing a Dorian sound. The effect is really dramatic. The long and the short of it is: if you hear a natural 7, by all means play it. It goes something like this:
If you lower the 6th degree of a Dorian scale, you get an Aeolian Mode or Natural Minor Scale. The chord symbol defined by this scale is Minor7 b6, which is rarely seen. This scale is used as the six shord when playing in diatonic major key oriented tunes (A-7 in the key of C). Basically, the flat 6 is a usable option as a color tone, but it is not used as a point of rest or emphasis in the same way that the natural 6 is. Aeolian looks like this:
If the 2nd degree of the Aeolian is lowered, it creates a Phrygian Mode. It is used as the three chord in a diatonic Major key (E- in the key of C) as used in the chord progression E-7 A-7 D-7 G7 CMaj7. Other uses are as the defining scale for the chord symbols C-phryg., DbMaj7/C and Bb-/C. The most common usage is in modal situations and could be thought of as suggestive of Spanish music. The Phrygian scale needs to be heard for a longer period of time to be effective. Trane’s compostion Transitions is an excellent example of this scale as the basis for improvisation.
For a discussion of Harmonic Minor, see Dominant Scales, below.
“Don’t take the hair dryer with you in the shower” is an example of a rule that should always be followed. Any rules mentioned above can be broken as often as you like. It’s your solo.
There are four commonly used Dominant Scales, with two being unaltered, the other two altered. The choice betwen unaltered or altered can be summed up generally as: If a Dominant Chord is resolving up a fourth, use an altered dominant; if it is moving elsewhere, unaltered. Blues changes are a notable exception, since the first chord establishes the tonic, even though it resolves up a 4th in measure two.
The first scale is known as the Myxolydian Mode and is the basic choice for playing over Dominant chords. It looks like this:
Only use the fourth degree as a point of emphasis when you want the “sus” sound as it tends to obscure the sense of tension, which makes the resolution sound weak. Also, a passing tone is commonly added between the root and the b7, yelding what is known as the “Bebop Scale.”
As with Major Scales, the problem of the 4th degree as a point of emphasis is solved by raising it a half step, yielding a Myxolydian #4. A brief rant: some folks call this a “Lydian b7”. To me this is misleading, since a Lydian scale is a Major Scale not a Dominant Scale. End of rant. The Myxolydian #4 looks like this:
This scale can be used on any dominant chord regardless of context, with the raised 4th degree usable as a point of emphasis/rest. An easy way to get the characteristic sound of this scale is to play the major triad bulit on the 2nd scale degree (D triad on C7+4). The chord asociated with this scale is sometimes writen as C7b5. In actuality, the 5th is not flatted, the 4th is raised. Oops, I ranted again.
Once the 4th degree is raised, the only two area that can be altered are the 2nd (9th) and 6th (13th) degrees. This is done to provide more points of resolution when resolving up a fourth. When you alter the 2nd degree, it is raised and lowered, resulting in an 8-note scale known as the Diminished Scale. It is the scalar equivalent of a Dominant Chord with b9, #9, #11 and natural 13. It looks like this:
The chord symbol that typifies the Diminished Scale sound is C13b9. This scale is created by playing alternating half steps and whole steps. (If you remember it as a dominant with a b9, you will never be confused about whether you start with a whole step or half step.) Example 3 of Lesson 5 uses this scale. The 13 tells you that the Diminished Scale is the first choice rather than the Altered Scale below:
The Altered Scale is a 7-note scale with no 5th degree, and is the equivalent of a Dominant Chord with b9, #9, #11 and b13. This is the big distinction between Altered and Diminished. Actually, it’s not that big is it? One way to choose is: when resolving to a Major Chord use Diminished, when resolving to a Minor Chord use Altered. Then break this “Rule” frequently. Very frequently. An easy way to remeber the Altered Scale is to think of the Melodic Minor Scale built on the flat 9th degree. I guess that means that this scale is a mode of Melodic Minor…
The Whole Tone Scale is a 6-note scale with raised 4th and 5th degrees., and is the equivalent of a Dominant Chord with 9, #11 and b13. It has a very distinguishable character, and is a nice alternative when lookng for altered dominant ideas. Check out Wayne Shorter’s tune Juju to hear a whole tone motif.
Minor7 b5 Scales
There are two scales to use over a Minor 7 b5 (Half-Diminished) chord, and they are identical except for the 2nd degree. These chords most often appear as the ii chord when resolving to a minor key, but the Locrian is not the most common choice in this situation. It is the most common choice when the chord is built on the #4 in a major key progression. Ladies and gentlemen, the Locrian Mode:
This is the seventh mode of the Major Scale. It can be used whenever a Minor 7 b5 is called for (see above). The 2nd degree is not very usable as a point of rest or emphasis. To deal with this, raise it a half step to get:
Locrian #2. Not much imagination in the name department. Now the 2nd degree is more usable as a point of rest/emphasis, and for this reason gets my vote as the true sound of a Minor 7 b5 (Half-Diminished) chord.
For Diminished Scales, see Dominant Scales, above.