The tetrachord for deriving minor scales is the same as for major, but it is treated differently in two important ways: it starts at the top and descends, and the lower tone of the upper tetrachord is the same as the upper tone of the lower tetrachord — they interlock with no whole step between the tetrachords.
Here’s how to make a minor scale: face the keyboard with your four fingers at the ready. Pick a key, any key. Place your right hand 5 on it as the starter. Now do the Whole, Whole, Half pattern descending from that starter key. That will be the upper tetrachord of the minor scale.
Now take your left hand 2 and place it on the same key as your right hand 2, and consider it to be the new starter. Now go down WWH. Note that the letter name you began with is now a whole step away, and making tht final step is how you complete the descending scale.
Let’s look at a couple of examples. Start on good old C, and don’t forget we’re descending!!
C starter, down W = Bb, down W = Ab, down H = G. Now Left hand 2 on G. Down W = F, down W = Eb, down H = D, and the whole-step left over is obvi0usly to tonic C.
Let’s try an Ab start. Right hand 5 on Ab, down W = Gb, down W = Fb (not E, since letter names must be in consecutive order), down H = Eb. Now left hand 2 is on Eb, down W = Db, down W = Cb (again, it is not a B), down H = Bb, and tonic Ab is W down.
Types of minor
The minor scale just described is called “signature minor.” This is because every minor scale shares its key signature with a major scale. They are, to continue the genetics metaphor, very closely related. Indeed, they are actually called “relative major and relative minor”. So it is called “signture minor” because it shares the exact set of flats or sharps found in its key signature.Sometimes it is called “natural minor”, but I find that name confuses some because they think natural signs are involved.
Finding relative minor and major
Once you have derived a major scale, its relative minor is always the sub-mediant, VI. Conversely, once you have derived a minor scale, its relative major is always the mediant, III. So the relative minor of Bb major is step VI — G minor. And the relative major of C minor is step III — Eb major.
Other versions of minor
In the article “Scales Major” the strong pull of VII up to I in a major scale was mentioned. This is, of course, most apparent in an ascending scale or as part of harmony. We have not talked about harmony at all in this discussion of scales. But now is the time to briefly touch on the topic.
The Dominant chord in major has step VII as its third (the full chord is V, VII, II), and this is a very important part of the strength of a Dominant chord. You will notice that from VII to I in signature minor is a whole step. This lack of half-step considerbly weakens the effect of the Dominant chord by removing the one element which pulls the ear to tonic, presumably in the next chord, namely the half-step from VII to I.
Long ago two solutions were worked out: (1) Harmonic minor, and (2) Melodic minor.
(1) Harmonic minor
Since the Leading tone (VII) to Tonic (I) relationship in signature minor is a whole step, and a half-step is what is needed to strengthen the harmonic movement, the solution is simplicity itself. Just raise VII a half-step from its place in signature minor. This works for harmonies very nicely!
Now that we’re discussing harmony, please take note of the more specific use of Roman numerals. An upper case numeral indicates a major chord and a lower case numeral indicates a minor chord. This will be so in all discussions involving harmony.
Just try the comparison in good old C minor. First do it with the altered minor.
V: G, B, D — a G major chord — to i: C, Eb, G.
That’s the sound our ears want. To hear why it is more effective, now play the signature minor version.
v: G, Bb, D — a G minor chord — to i: C, Eb, G.
While the effect has a certain colorful ancient-music sound, it certainly lacks the strength of the altered V-i.
(2) Melodic minor
Harmonic minor is just fine for inserting the VII-I half-step in chords, but it leaves a lot to be desired when used for melodic writing. That augmented 2nd from VI to VII is exotic and typical of middle-eastern music, but not the stuff of smooth lines which we tend to like in Western European music.
So a more subtle kind of minor was devised to supply both the VII-I half-step and a smooth line. So the solution is to replace the minor upper tetrachord with a major upper tetrachord but leave the lower structure the same as in signature minor.
Again, good old C minor will now read: C, D, Eb, F, G, A, B, C. Our ears are set up to hear it as minor because it begins with the minor lower tetrachord. But the major upper tetrachord smooths out the interval of the augmented 2nd.
But when one is descending with those same pitches, having a major scale sound first sets up the ear for the wrong thing. It sounds like major with a disconcerting shift to minor half-way through.But the need for VII-I only matters in an ascending line since that is the only direction in which VII-I occurs in that order. So descending we simply use signature minor.
Minor review
Signature, ascending: I starter, up W to II, up H to III, up W to IV, up W to V, up H to VI, up W to VII, up W to I.
Harmonic, ascending: I starter, up W to II, up H to III, up W to IV, up W to V, up H to VI, up W+H to VII, up H to I.
Melodic, ascending: I starter, up W to II, up H to III, up W to IV, up W to V, up W to VI, up W to VI, up H to I; descending: I starter, down W to VII, down W to VI, down H to V, down W to IV, down W to III, down H to II, down W to I.
more articles by Paul Somers
