Backdoor progression

In jazz and jazz harmony, the chord progression from iv⁷ to ♭VII⁷ to I (the tonic or "home" chord) has been nicknamed the backdoor progression^[1][2] or the backdoor ii-V, as described by jazz theorist and author Jerry Coker. This name derives from an assumption that the normal progression to the tonic, the ii-V-I turnaround (ii-V⁷ to I, see also authentic cadence) is, by inference, the "front door", a metaphor suggesting that this is the main route to the tonic.

Backdoor compared with the dominant (front door) in the chromatic circle: they share two tones and are transpositionally equivalent.

The ♭VII⁷ chord, a pivot chord borrowed from the parallel minor of the current tonic major key, is a dominant seventh. Therefore, it can resolve to I; it is commonly preceded by IV going to iv, then ♭VII⁷, then I. In C major the dominant would be G⁷: (the notes GBDF), sharing two common tones with B♭⁷: (the notes B♭DFA♭). The notes A♭ and F serve as upper leading-tones back to G and E (when the chord moves to the tonic, C major), respectively, rather than B♮ and F serving as the lower and upper leading-tones to C and E in a conventional G7-C major (V7-I) cadence.

A backdoor IV-V is also possible, moving from ♭VI^M7 to ♭VII⁷ to I. This is also commonly known as "Mario Cadence".^[3]

Alternative usage

 

Berg's "Backdoor progression" to iii, with I in place of iii: ♯iv^ø7-VII^7(♭9)-I^maj9 Playⁱ

The term "Backdoor" has been used by author Shelton Berg to refer to another entirely unrelated progression. The unexpected modulation created through the substitution of the highly similar I^maj9 for iii⁷ (in C: CEGBD and EGBD) at the end of the ii^ø7-V⁷ turnaround to a tonicized iii (ii^ø7/iii=♯iv^ø7, V⁷/iii=VII⁷, iii), arrives at 'home' (the temporary tonic of iii) through unexpected means, the 'back door' instead of the 'front door'(iii⁷, the individual notes EGBD, being entirely contained within I^maj9, the individual notes of the C major chord, CEGBD, and the seventh of the dominant seventh chord still resolving downward).^[4] The resolution of a dominant seventh chord up a step (in this case a half-step, also called a semitone) is called a deceptive cadence.

See also

• ♭VII-V7 cadence

References

1. Coker, Jerry (1997). Elements of the Jazz Language for the Developing Improvisor, p.82. ISBN 1-57623-875-X. "Back Door Progression As A Substitute For V7[:] The I chord, in a given progression, is often preceded by IV-7 to ♭VII7, instead of the usual V7 chord.".
2. Juusela, Kari (2015). The Berklee Contemporary Dictionary of Music, unpaginated. Hal Leonard. ISBN 9781495028540. "back-door cadence: A IVmi7 ♭VII7 I harmonic cadence."
3. Lavengood, Megan (July 1, 2021). "Open Music Theory: Modal Schemas" – via viva.pressbooks.pub. {{cite journal}}: Cite journal requires |journal= (help)
4. Berg, Shelton (2005). Essentials Of Jazz Theory, p.105. Alfred Music. ISBN 0-7390-3089-2.