C7 guitar chord — root mapping, fingerings, arpeggios, triads, pentatonic, scales

The Altered scale is the seventh mode of melodic minor and the main scale used over 7alt. It contains the major 3rd and minor 7th of a dominant chord but no natural 9th or perfect 5th; instead it provides b9, #9, b5 and #5. Nearly every note therefore lies a half step from a tone of the following tonic. The scale is widely used in jazz and fusion before either major or minor resolutions.

Altered is a dominant scale containing the root, major 3rd, and minor 7th of a 7 chord together with all four standard alterations of its 9th and 5th: b9, #9, b5, and #5. It contains no natural 2, 5, or 6, meaning no natural 9, perfect 5, or natural 13. The two semitone areas 1–b2 and #2–3 surround the root and major 3rd with strong chromatic tension. The major 3rd and minor 7th preserve the dominant foundation, while the altered 9ths and 5ths make the sound highly tense and directed toward resolution. Its defining profile is 1 b9 #9 3 b5 #5 b7.

In jazz chord-scale notation, the scale is written 1 b2 #2 3 b5 #5 b7 so that the altered dominant tensions are immediately visible. In strict diatonic spelling with seven different letter names, it is 1 b2 b3 b4 b5 b6 b7: b3 is reinterpreted as #9, b4 as the major 3rd 3, and b6 as #5 or b13.

1 — chord root: the foundation of the 7alt chord and the reference point for all altered tensions.

b2—minor 2nd / flat 9th: functions as the b9, lies a semitone above the root, and creates one of the scale’s principal tensions.

#2 — augmented 2nd / sharp 9th: functions as the #9 and lies a semitone below the major 3rd. In strict modal spelling, this pitch is written as b3.

3 — major 3rd: establishes the dominant quality and forms the chord’s essential tritone with b7. In strict spelling of the seventh mode of Melodic Minor, this pitch is written as b4.

b5—diminished 5th: one of the altered 5ths; it may also be interpreted as a #11 when functioning as an upper extension.

#5 — augmented 5th: the other altered 5th. It is enharmonically equivalent to b13; the preferred name depends on the chord voicing and voice leading. In strict modal spelling, it is b6.

b7—minor 7th: an essential dominant seventh chord tone that forms a tritone with the major 3rd 3. It normally moves downward when the dominant resolves.

Harmonization must use the strict spelling 1 b2 b3 b4 b5 b6 b7, not the jazz reinterpretation of the degrees as b9, #9, 3, b5, and #5. Otherwise, the sequence of diatonic 3rds will be spelled incorrectly.

Harmonizing the strictly spelled scale in triads produces:

i° — diminished; bii — minor; biii — minor; biv+ — augmented; bV — major; bVI — major; bVII° — diminished.

The seventh chords are iø7, bii(maj7), biii7, bivmaj7#5, bV7, bVI7, and bVIIø7.

The main practical chord is not obtained by treating the first degree as an ordinary tertian tonic chord. Instead, the scale is reinterpreted in jazz terms: 1 3 b7 form the dominant seventh foundation, while b2, #2, b5, and #5 function as altered tensions. Altered is therefore used primarily as a chord scale for 7alt, not as an independent system of diatonic harmony.

C Altered in strict spelling contains C Db Eb Fb Gb Ab Bb. Its triads are Cdim Dbm Ebm Fbaug Gb Ab Bbdim; its seventh chords are Cm7b5 Dbm(maj7) Ebm7 Fbmaj7#5 Gb7 Ab7 Bbm7b5.

In jazz notation, the same pitches are commonly written C Db D# E Gb G# Bb to show C7(b9,#9,b5,#5). This spelling is useful for improvising over the chord but is not intended for literal tertian harmonization.

Altered is used primarily over altered dominant seventh chords marked 7alt. This symbol preserves the root, major 3rd, and minor 7th while allowing various combinations of b9, #9, b5, and #5. A particular chord voicing does not have to contain all four alterations simultaneously.

Its most typical setting is a functional dominant resolving down a perfect 5th or up a perfect 4th: V7alt–I in major and V7alt–i in minor. For example, G Altered is used over G7alt resolving to either Cmaj7 or Cm.

The scale fits symbols such as 7b9#5, 7#9b5, 7b9b5, 7#9#5, and other dominant combinations of altered 9ths and 5ths. The symbol 7alt leaves the precise selection of tensions to the performer and the musical context.

Altered contains no natural 9, perfect 5th, or natural 13. When these pitches are explicitly present in the melody or chord symbol, another dominant scale normally represents the harmony more accurately. Mixolydian is used for an unaltered 7; Lydian Dominant for 7#11 with natural 9 and 13; and Phrygian Dominant may fit 7b9b13 without #9 or b5.

Altered is also connected with the tritone substitution. The scale rooted on a dominant contains the same pitches as Lydian Dominant rooted a tritone away. For example, G Altered and Db Lydian Dominant both contain the notes of Ab Melodic Minor. The same pitch collection can therefore describe both G7alt and its tritone substitute Db7#11.

Altered is the seventh mode of Melodic Minor. Its relative parent Melodic Minor scale begins a semitone above the Altered root. For example, C Altered and Db Melodic Minor contain the same pitches: C Db Eb Fb Gb Ab Bb, enharmonically C Db D# E Gb G# Bb.

Other common names are Super Locrian and Diminished Whole-Tone. The name Super Locrian refers to the strict formula 1 b2 b3 b4 b5 b6 b7: compared with ordinary Locrian, the 4th is lowered as well. The name Diminished Whole-Tone refers to its interval pattern H–W–H–W–W–W–W.

Ordinary Locrian has the formula 1 b2 b3 4 b5 b6 b7 and uses a perfect 4th instead of b4. In jazz notation, the b4 of Altered is reinterpreted as the major 3rd 3 required by the dominant seventh chord.

Half-Whole Diminished has the formula 1 b2 #2 3 b5 5 6 b7. Its first five degrees match Altered, but it continues with a perfect 5th and natural 13, whereas Altered contains #5 or b13 and no natural 5.

Whole-Tone has the formula 1 2 3 #4 #5 b7. It shares 1, 3, b5/#11, #5, and b7 with Altered, but uses a natural 9 and contains neither b9 nor #9.

The seven modes of Melodic Minor are:

1 — Melodic Minor: 1 2 b3 4 5 6 7;

2 — Dorian b2: 1 b2 b3 4 5 6 b7;

3 — Lydian Augmented: 1 2 3 #4 #5 6 7;

4 — Lydian Dominant: 1 2 3 #4 5 6 b7;

5 — Mixolydian b6: 1 2 3 4 5 b6 b7;

6 — Locrian Natural 2: 1 2 b3 4 b5 b6 b7;

7 — Altered: strict spelling 1 b2 b3 b4 b5 b6 b7, jazz spelling 1 b2 #2 3 b5 #5 b7.

Over 7alt, begin with the root, major 3rd, and minor 7th: 1 3 b7. Degrees 3 and b7 form the guide-tone tritone and preserve the dominant function within the dense alterations. Since the 5th may be lowered or raised, it is not the same neutral structural tone that it is in Mixolydian.

Then add the altered tensions b9, #9, b5, and #5. To make the line sound clearly Altered, use relationships such as 1–b9, #9–3, 3–b5, and b5–#5, resolving them into nearby tones of the following chord. Simply running the complete scale is less effective than building phrases around directed chromatic voice leading.

Over G7alt–Cmaj7, B, the dominant’s major 3rd, normally rises to C, while F, its minor 7th, falls to E. The altered tensions also have several close resolutions: Ab (b9) may move to G or A, Bb (#9) to A or B, Db (b5) to C or D, and Eb (#5/b13) to D or E. The exact choice depends on the melodic line and the voicing of the target chord.

Over G7alt–Cm, B again rises to C, while F normally falls to Eb. The note Eb, functioning as #5 or b13 over G7, may remain as a common tone and become the minor 3rd of Cm; Ab commonly resolves to G.

Arpeggios containing the altered tensions can help organize the material. Over C7alt, a Db minor triad supplies b9, 3, and #5; an Eb minor triad supplies #9, b5, and b7; a Gb major triad supplies b5, b7, and b9; and an Ab major triad supplies #5, 1, and #9. These structures should be heard relative to C and resolved as tensions of C7alt.

It is also useful to practice the parent Melodic Minor scale beginning a semitone above the dominant root, but the current dominant chord must remain the center during improvisation. Over G7alt, the notes of Ab Melodic Minor may be used, but G, B, and F remain the structural tones rather than hearing Ab, Cb, and Gb as the tonic, 3rd, and 7th of the parent scale.

Avoid sustaining the natural 9, perfect 5, or natural 13 when a pure Altered sound is intended. Introducing them changes the tension set and moves the line toward Mixolydian, Lydian Dominant, Whole-Tone, or Half-Whole Diminished.

Altered is the seventh mode of Melodic Minor and the most extensively altered common dominant scale. Its jazz formula is 1 b9 #9 3 b5 #5 b7: the root, major 3rd, and minor 7th establish the 7alt foundation, while both altered 9ths and both altered 5ths provide the maximum chromatic tension set without a natural 9, perfect 5, or natural 13. Its primary application is a functional V7alt resolving to a major or minor tonic.