Interval of a 6th

From “The 6th¨ in Music Theory for Electronic Music Producers

Unlike the 4th, which is a perfect interval, the 6th can be major or minor. […] when we talked about the 3rd, we learned that the 3rd is very powerful because it determines if the chord is major or minor. The 6th carries some of the power with it, because it is an inversion of the 3rd.

The interval of a 6th is the space, move or span of an inclusive count of 6 (mechanical) keys or their corresponding pitches from a musical key of a musical scale up or to the right of a standard Western classical piano keyboard or piano roll editor. In sum, it is an inclusive distance of 6 diatonic (mechanical) keys or their corresponding pitches. The half-step distance in chromatic keys may vary. The below exemplifies a 6th with a major quality starting from C in the key of C major scale (refer to 20240904103821-Musical_Scale_and_Key_Patterns & 20240903174948-Being_“In_Key”), which chromatically has 9 half-steps (refer to 20240831190951-Musical_Alphabet & 20240831200842-Musical_Accidentals).

A (diatonic) minor interval of a 6th will likely have a different amount of chromatic half-steps.

Distinguishing Major v. Minor Intervals

For distinguishing major and minor intervals, see Perfect and “Imperfect¨ Inversions.

The interval of a 6th can play the same role as the interval of a 3rd in distinguishing major and minor chords, especially “larger¨ triad chords. Reminder of the way the interval of a 3rd has this role in triad chords:

20240928130915-Two_Thirds_in_Triads

Two Thirds in Triads

Chords

For background on what a chord is, see 20240904095922-Chords & 20240924121346-What_Chords_Are.

From bib. source

[…] in order to make a minor triad we have two thirds: a minor third on the bottom, and a major third on the top. The diminished chord breaks this rule: It is made of two minor thirds.

That is, triads are made of “two thirds,¨ with a minor triad having a “minor third¨ on the bottom (i.e., on the right on a standard Western classical piano) and a “major third¨ on the top (i.e., on the left on a standard Western classical piano) (Allen 2018, 79). The converse is the case for a major triad, wherein the minor third is on the top and the major third is on the bottom.

The minor thirds and major thirds of a C major triad chord, built on/from the C Major scale, would look like this:

This can help us understand a little bit more how chords built from a scale sit within the sequence of the musical alphabet with its accidentals:

Chromatic Interval Variability of Diatonic Chords

Further, the D triad from C major scale and the C triad from C major scale both have the same interval relationships in their notes / (mechanical) keys / pitches within their shared scale key, yet their interval relationships actually diverge if one pays attention to the entirety of the musical alphabet together with its accidentals (see 20240831190951-Musical_Alphabet & 20240831200842-Musical_Accidentals).

D Triad v. C Triad Chord Intervals in Key of C Major Scale

The C triad’s sequence has 4 half-steps from its “first¨ to its “third¨ and 3 half-steps from its “third¨ to its “fifth.¨ Yet the D triad has this reversed in its sequence. This is what makes the D triad from C Major scale a minor chord, and the C triad from C major scale a major chord. Both have the same total of 7 half-steps from start to end.

C triad chord in the key of the C major scale is a major chord:

An A chord triad in the key of the C major scale is a minor chord:

Essentially (Allen 2018, 70 & 72):

From “Major vs Minor¨ in Music Theory for Electronic Music Producers

The number of half steps between C and G is seven, and the number of half-steps between D and A is seven. So the distance from the root to the fifth is seven - whether a chord is major or minor - the distance between the root and the fifth stays the same[sic]. The distance between the root and the fifth is an interval that we already know - it’s a perfect 5th. So in order to make a triad, we need a perfect 5th and one note inside of the perfect fifth - the third.

Building Triadic Chords from Diatonic Perfect Fifths

Evidently, another way to think about triads is as perfect fifths, when including all (mechanical) keys / pitches / notes, from the chord root, with a (mechanical) key / pitch / note in-between, the “third¨ (for more on perfect fifths, see 20240901171406-Musical_Intervals) (Allen 2018, 72). Thinking of triads this way makes it easier to practice switching between major and minor triads in the key of a given scale (Ibid):

From “Major vs Minor¨ in Music Theory for Electronic Music Producers

[…] the only difference is the third. And even more clear now is that the different[sic] between the two thirds is just a half-step. If we have a major triad and we want to turn it into a minor triad, you just have to lower the third one half-step. Similarly, if we want to turn a minor triad into a major triad, you just have to raise the third by one half-step.

Examples of perfect fifths in the key of C Major scale (refer to 20240901171406-Musical_Intervals, 20240903174948-Being_“In_Key” & 20240904103821-Musical_Scale_and_Key_Patterns):

major_scale C_major_scale root_key root_pitch root_note chord_root scale_root scale_degree perfect_fifth musical_alphabet intervals scale_degrees conventionalism music_theory musical_scale minor_triad major_triad musical_key half-step semitone chord_quality musical_chord


bibliography

  • “The Basic Triad.” In Music Theory for Electronic Music Producers: The Producer’s Guide to Harmony, Chord Progressions, and Song Structure in the MIDI Grid., 1st ed., 70–71. Minneapolis, MN: Slam Academy, 2018.
  • “Major vs Minor.” In Music Theory for Electronic Music Producers: The Producer’s Guide to Harmony, Chord Progressions, and Song Structure in the MIDI Grid., 1st ed., 72–73. Minneapolis, MN: Slam Academy, 2018.
Link to original

Defining Minor and Major Thirds

One way of looking at this then is that a minor third is a 3 half-step distance away from the center of a chord triad, while a major third is a 4 half-step distance away from the center of a chord triad.

A diminished chord within this scheme would be comprised of two minor thirds (Ibid):

If you count the half-steps from each key in the triad chord above, you’ll notice that walking from the third (i.e., the second highlighted note / [mechanical] key) is the same 3 half-step distance (refer to Scale Degrees and Triadic Chord Construction for more on what a third is). 3 half-steps is a ”minor third¨ distance in a triad chord.

Diminished Chord Abbreviation

Perhaps “dim¨ then stands for “diminished,¨ to answer the question at the end of 20240927133630-What_is_a_Diatonic_Chord_Progression.

minor_chord major_chord minor_triad major_triad scale musical_scale major_scale minor_third major_third C_major_scale semitone music music_theory musical_alphabet diminished_chord chord_quality musical_key


bibliography

  • “Diminished Triads.” In Music Theory for Electronic Music Producers: The Producer’s Guide to Harmony, Chord Progressions, and Song Structure in the MIDI Grid., 1st ed., 79. Minneapolis, MN: Slam Academy, 2018.
Link to original

major_chord chord_inversion interval_quality major_interval minor_interval major_sixth minor_sixth minor_third major_third half-step semitone major_scale C_major_scale music_theory pitch major_6th_interval minor_6th_interval


bibliography

  • “The 6th.” In Music Theory for Electronic Music Producers: The Producer’s Guide to Harmony, Chord Progressions, and Song Structure in the MIDI Grid., 1st ed., 95. Minneapolis, MN: Slam Academy, 2018.