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Basic Music Theory for Guitar: What You Actually Need
The essential music theory every guitarist should know - notes, intervals, scales, keys, and chord construction. No fluff, just practical theory you'll use.
B diminished guitar shapes
Popular fretboard positions with fingering suggestions
Showing 8 of 49 playable shapes
About the chord
B diminished guitar chord
Bo is the B diminished guitar chord. It uses the notes B, D, and F and the interval formula 1-♭3-♭5.
The B diminished diminished chord is built from minor thirds, including a diminished fifth F, producing a tense, unstable sound. This dissonant, unresolved tension is commonly used for dramatic transitions, suspenseful moments, or eerie atmospheres in classical, jazz, and film music.
Also written as Bdim and Bm♭5.
Root note: B
Quality: diminished
Chord tones: 3
Playable shapes: 49
Chord tones
BDF
Common guitar voicings
These are quick-start shapes for players who want the answer first and the deeper theory second.
Shape 1
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- 1 Place the 1st finger on the 7th fret of the 6th string.
- 2 Place the 2nd finger on the 7th fret of the 3rd string.
- 3 Place the 3rd finger on the 8th fret of the 5th string.
- 4 Place the 4th finger on the 7th fret of the 1st string.
- 5 Strum from the 6th string down.
Shape 2
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- 1 Place the 1st finger on the 9th fret of the 4th string.
- 2 Place the 2nd finger on the 10th fret of the 3rd string.
- 3 Place the 3rd finger on the 10th fret of the 1st string.
- 4 Strum from the 4th string down.
Notes & Intervals
Each note below shows how the chord is built from its root. This is the theory layer underneath the fretboard shapes.
B Unison (Root) 1
The root anchors the chord and defines its tonal center.
D Minor Third ♭3
This note supplies the minor color and gives the chord its darker emotional pull.
F Diminished Fifth ♭5
The flattened fifth adds tension and a restless, unstable edge.
Quick answers
What notes are in Bo?
Bo uses the notes B, D, and F. Its interval formula is 1-♭3-♭5.
What is another name for Bo?
Bo is also written as Bdim and Bm♭5.
How do you play Bo on guitar?
Place the 1st finger on the 7th fret of the 6th string. Place the 2nd finger on the 7th fret of the 3rd string. Place the 3rd finger on the 8th fret of the 5th string. Place the 4th finger on the 7th fret of the 1st string. Strum from the 6th string down.
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