4ado is the arithmetic equal division of the octave into four parts of 1/4 each. 4ado is perhaps the smallest ADO that contains useful intervals for harmony, containing athemajor third, perfect fifth, and harmonic seventh.

Intervals

# Cents Ratio Interval name
0 0 1/1 perfect unison
1 386.3 5/4 just major third
2 702.0 3/2 just perfect fifth
3 968.8 7/4 harmonic seventh
4 1200.0 2/1 perfect octave