Music Theory Resources

Harmonic Function

Roman Numerals and Scale Degrees for Major Keys

The Omnibus AKA “chromatic wedge progression”

The omnibus is a wedge-shaped chromatic chord progression that encompasses all the notes of the chromatic scale.

Characterized by two voices moving in contrary motion (by half-steps), while the other two voices share common-tones (which change every four chords.

It is circular, the beginning and ending chords are identical

Based on a minor third chromatic mediant relationship.

There are always at least 4 voices

Goes through the minor-third key sequence, (ex. c-eb-f#-a)

Consists of two basic chords

German augmented-sixth chord

 Minor tonic six-four chord

Typically has a descending bass line, and ascending tetrachords in the non-bass voices.

C G6

5 B♭7 Dm6

4 B♭4

2 G7 C

A more extended treatment of this version of the omnibus could be:

C G6

5 B♭7 Dm6

4 B♭4

2 G7 Bm6

4 G4


E7 G♯m6

4 E4

2 C♯7 Fm6

4 C♯4

2 B♭7 Dm6

4 B♭4

2 G7 C




Schubert's Piano Sonata in A minor, Op. 42, first movement, mm. 32–39


Brahms, Rhapsody in G minor, Op. 79, No. 2, mm. 13-15.

 The second theme begins with a German augmented-sixth chord in the key of d-minor. It moves to a major-minor seventh chords on GBDF, which does not have a clear function in the key of d minor. The two chords share pitches D and F. Bb moves to B, G# moves ti G.


Tchaikovsky Piano Concerto No. 2, Op. 44: I:cadenza, mm. 394-416

 Pathetique Symphony movement 1


Beethoven Symphony No. 2, Op. 21: I, mm. 326-340.



Can be used in whole or in part

Sometimes used as a prolongation of the dominant-seventh chord. In this case, the progression will consist of five chords, beginning and ending with the dominant-seventh chord.


Like the diminished-seventh chord, there are only three transpositions



Alternate version (Vogler)

substitutes a fully-diminished seventh chord for the inverted augmented0sixth chord, with the bass note of the augmented0sixth chords (the inverted seventh) as the root of the diminished-seventh chord.