comma pump

A circular chord progression, which can only be executed when the tuning allows every adjacent pair of chords in the progression to have at least one common-tone.

The most typical example is the one in 12-edo which is normally described in harmonic analysis as I - vi - ii - V - I, in which the syntonic comma is tempered out; hence the name. I give a very full description of the discrepancies between the 12-edo and JI versions of this progression in the xenharmonic bridge definition.

A different example of a "comma pump" progression, composed by Graham Breed in blackjack tuning, may be found about 4/5 of the way down on my blackjack page.

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updated: 2002.2.7

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For many more diagrams and explanations of historical tunings, see my book. If you don't understand my theory or the terms I've used, start here

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