C#dim7

C#dim7 is C#, E, G and Bb, a diminished seventh. The shape this page opens on is written xx2323, lowest string first.

Note by note. C# is the root, E is the minor third, G is the flat fifth and Bb is the diminished seventh.

Also written C#°7, C#o7 or C# diminished 7. The same chord either way; which spelling you meet depends on who wrote the chart.

There are 6 common shapes for C#dim7 on the guitar, and 30 derived voicings in 4 families.

One note away. Change a single note of C#dim7 and you have C#dim (with one note taken away), C#m6 (with one note moved), C#m7b5 (with one note moved) or C#mMaj7b5 (with one note moved).

The common shapes, written lowest string first: xx2323, x45353, xx5656, 9x8989, 9-10-11-9-11-9, x-x-11-12-11-12.

Under the hand. None of the shapes for C#dim7 uses an open string, so every one of them is movable; the lowest sits at the 2nd fret. 2 of the 6 need a barre. Together they cover the neck from the 2nd fret to the 12th.

Where it goes. A diminished seventh divides the octave evenly, so C#dim7 has no single root and no single destination: it can lead to F# or to D, and it is the same four notes either way.

Shell. Root, third and seventh: the guide tones fix the quality, so the fifth is dropped. That is what leaves a string free, so pick a tension to put on top. C#dim7 has x4x353, 9x898x, x4898x, 9-7-8-12-x-x, 9-13-14-12-x-x.

Drop 2. A close-position chord with the second voice from the top lowered an octave. Sits on four adjacent strings. C#dim7 has x1202x, 3423xx, xx2323, x4535x, xx5656, 6756xx, x7868x, xx8989.

Drop 3. The third voice from the top lowered an octave. The dropped voice becomes the bass, which is why a string is skipped. C#dim7 has x1x020, 3x232x, x4x353, 6x565x, x7x686, 9x898x, x-10-x-9-11-9, 12-x-11-12-11-x.

Open string. An open string left ringing against a fretted grip. Because it costs no finger, it sounds a note the closed shape has none left for -- a tension on top, or a pedal root underneath. Either a familiar grip with open strings added, or a shape so sparse the open strings carry the chord. These belong to their key rather than to a shape, so D, A, G and E have many and Eb a handful. C#dim7 has 005656.

Tensions. A shell of C#dim7, root, third and seventh, leaves a string free, and the tones that belong over it are the 9 (D#), the 11 (F#), the b13 (A) and the maj7 (B#).

What kind of chord this is. C#dim7 is a diminished chord — root, minor third, flat fifth. diminished and half-diminished chords on every root, and what they are for.

The common shapes and the derived voicings come from different places, and both are explained in where the chords and the theory come from.