Arpeggio quality

dim

The diminished triad lowers both the third and the fifth of a minor triad, stacking two minor thirds into a tense, unstable shape. It is rarely a destination: it appears as a passing chord between ii and I, as the top of a dominant flat-nine sound, and as a colour that makes a minor progression ache. Because the flat fifth is the tritone, the chord already contains the seed of resolution, but with no seventh it stays ambiguous. On the neck the shape is symmetrical, so it moves easily in minor thirds. Listen for the flat fifth leaning against the root — that compressed interval is the whole tension.