Heptachord

Heptachord, from Greek heptachordos, from ancient greek ἑπτάχορδος, from ἑπτά + χορδή, is a 7-stringed lyre of ancient Greece, the interval of a seventh, or a diatonic scale of seven notes or tones.

7-stringed lyre

Most of the ancient greek lyres had 7 strings. Early lyres originate in ancient Mesopotamia.

Interval of a seventh

Two intervals are possible:

Minor seventh, 10 semitones

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Major seventh, 11 semitones

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Diatonic scale of seven notes

A heptachord is based on two consecutive tetrachords.

Basic tetrachords

1½1, ½11, 11½, 111

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7 modes

The 7 modal patterns for the Babylonian heptachords are:

Mode	Pattern	Center note	Semitones	Tritones
kitmum	1½11½1	D	10	0
pītum	½11½11	E	10	0
qablītum	11½11½	C	10	0
išartum	1½111½	G	10	1
embūbum	½111½1	A	10	1
nīd qablim	111½11	B	11	2
nīš tuḫrim	11½111	F	11	2

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2 consecutive heptachords

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7 consecutive heptachords

6 cyclic consecutive heptachords

Tuning

A tuning procedure for a 7-stringed instrument based on a transposition to D/D:
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