Musical Composition, Theory and Songwriting/chords


I am learning a slow 12 bar blues in G major.
The chord progression is very different from the normal 12 bar progression I'm used to when jamming. Is that because it's a slow blues?

There is a Db9 in this progression but this chord is not even included in the key of G. How do we explain this chord?

ANSWER: Hello Hank and thank you for contacting me through

The Blues definitely has standard forms, but many other song forms are referred to as the Blues. The tempo of a tune usually does not affect the harmony, but there are some cultural preferences that may contribute to how a type of tune is performed.

While a simple Blues would be built with the I, IV, V chords there are also other harmonic choices one can use/add to make the tune more interesting.

A Dd9 is the tritone of the G chord so it is not surprising that your chart includes this chord. A tritone may be used as a substitution for the chord itself, or simply added in addition to the other chords.

Here is a chart exemplifying the tritones in all 12 keys:

Good luck and thanks for the interest,

D C DowDell
Professor of Music

---------- FOLLOW-UP ----------

Is it much more difficult to play jazz-blues than simple blues since there are more chords in jazz-blues? Is this even true? It looks harder to play.

"Difficult" is a relative term depending on your playing level & experience, so are the terms for music styles. It is all music really.

There are three basic components of music:

All three are used for expression. Using Harmony for expression (as with tritones & upper-level extensions like 9s, 11s & 13s) is usually referred to as Jazz, but Classical composers also did this, just in a different way.

Most people would say Blues is a simpler form of music, yes. In my opinion, the dynamic of Blues is not so much the harmony used, but the emotional feeling expressed.

Thanks for the interest,

D C DowDell
Professor of Music

Musical Composition, Theory and Songwriting

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D C DowDell


D C DowDell will answer questions about Jazz improvisation, composition, chord voicing, scales and modes, practice techniques and ear training. Professor DowDell also enjoys discussions on Jazz musicology and the evolution of style.

D C DowDell is a professional Jazz pianist/composer who currently teaches online Jazz studies at A Passion for Jazz!. Professor DowDell has been teaching music for over 30 years at 2 major universities, several community colleges as well as accepting students for private study.


American Federation of Musicians
National Music Teachers Association
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Bachelors of Music Education from UCLA
Masters of Music Composition from UNT

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