Mu chord

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Cadd9 chord and two different voicings of the Mu chord on C: left, About this soundmiddle ,[1] About this soundright .[2] Notice the major second between the second and the third in all instances.
Mu chord
Component intervals from root
perfect fifth
major third
major second
Forte no. / Complement
4-22 / 8-22

A mu major chord or mu chord (signified by μ) is a particular voicing of an add 2[2] or "add 9" chord. It is formed by adding a major second to a major triad. The voicing is associated with jazz-rock band Steely Dan. The mu major chord differs from a suspended second (sus2) chord, as suspended chords do not contain the major (or minor) third.


Extension of the Mu chord, the "Steely Dan chord" on C/E[3] About this soundPlay 

The reference to this chord as "mu major" has been popularized by fans of the jazz-influenced rock group Steely Dan, as well as by the band members themselves. This chord is used extensively in their work, often arpeggiated at the end of musical phrases. The "mu major sound" is a distinctive idiom of Steely Dan's style. In a 1989 interview with Paul Zollo, Walter Becker explained that the use of the chord developed from trying to enrich the sound of a major chord without making it into a "jazz chord".[3] In the Steely Dan Songbook, Becker and Donald Fagen state that "inversions of the µ major may be formed in the usual manner with one caveat: the voicing of the second and third scale tones, which is the essence of the chord's appeal, should always occur as a whole tone dissonance."[1]


An Eμ chord displayed as a guitar chord symbol and in notation[1] About this soundPlay 

The chord consists of a major triad with an added major second note. When the chord is voiced with the third in the bass, the presence of two stacked fourths in the upper register, between the second and the fifth, and the fifth and the root, gives the chord a quartal harmony flavour. The chord can also be voiced with the ninth (or second) in the bass, although such voicings are generally known as slash chords. It is suggested that the chord was conceived on or for use on keyboards.[2]

Mu chords, or portions thereof, may be used in chord substitution by replacing the major triad found in voicings of other chords. For example, an Am7 chord can be voiced as a C major triad (CEG) with an A in the bass. A Cμ chord can be voiced as a DEG triad with a C in the bass. Taking the upper portion (DEG) of the Cμ chord and substituting this in place of the C triad in the original Am7 chord would give an A7sus4 chord: DEG with A in the bass.[2]


Caligula's Horse's lead guitarist and composer, Sam Vallen, frequently uses mu chords in his compositions, having studied Steely Dan's harmonic vocabulary for his honours thesis.[4]


  1. ^ a b c Becker and Fagen. "Intro to the Steely Dan Song Book ", Posted 05/96.
  2. ^ a b c d Howard Wright 2002-2007. "Steely Dan Mu Major Chord", Howard Wright's Home Page.
  3. ^ a b "Winter 1989 interview with Walter Becker" Archived 2005-02-10 at the Wayback Machine, Metal Leg: The Steely Dan Magazine, Issue 14, Fall 1990.
  4. ^ Astley-Brown 2017-10-05T09:48:58.277ZGuitars, Michael. "10 questions for Caligula's Horse guitarist Sam Vallen". MusicRadar. Retrieved 2019-03-20.

Further reading[edit]

  • Zollo, Paul (2003). Songwriters on songwriting, p. 432. Da Capo Press. ISBN 978-0-306-81265-1.
  • (2006). Keyboard, Volume 32, Issues 1-6, p. 37. GPI Publications.