Diminished Seventh
The four basic chord types are major, minor, diminished and augmented. All the chords so far studied are based upon major or minor chords.
A diminished chord ( B ) has the formula 1 b3 b5. The diminished seventh chord is generally used instead of the basic diminished chord. The diminished 7 chord is created by adding the double flattened seventh note of the major scale to the diminished chord.
Although the correct name is diminished seventh it is commonly referred to as a diminished chord (although technically incorrect). When reading sheet music you can play a diminished seven chord (B7) when you see the diminished (B) chord symbol. Double flat (bb) means to lower the note pitch by one tone (2 frets on the bass guitar).
For example, The DbB7 chord is based upon notes of the Db major scale.
Db Major Scale
As the diminished seventh arpeggio consists entirely from consecutive minor 3rds piled on top of each other;
e.g., the notes of the DbB are Db , Fb , Abb and Cbb ,
Db - Fb = min 3rd,
Fb - Abb = min 3rd,
Abb - Cbb = min 3rd,
Cbb - Db = min 3rd etc. all inversions have the same pattern.
G Diminished Seventh Arpeggio Pattern
E Diminished Seventh Arpeggio Pattern
Db Diminished Seventh Arpeggio Pattern
The diminished seven chord arpeggio actually has four different names. To understand why this is so examine the formula for a diminished seven chord, 1 b3 b5 bb7. By applying this formula to the respective scales of each note in the chord, it may be seen that DbB7, EB7, G7 and BbB7 all contain the same notes, thus the same arpeggio may be used for all four chords.
The chord arpeggios can be called either DbB7, EB7, GB7 or BbB7 .
The following table illustrates this point by showing that the notes in each chord are the same.
DbB7, can also be called C#B7, BbB7 can also be called A#B7.
As each arpeggio represents four different dim7 chords, all the diminished seven chords can be covered in just three frets. The following example refers to the 5th string.
For example, At the 2nd fret the diminished 7 chord is Db/C#, Fb/E, Abb/G, Cbb/Bb
At the 3rd fret the diminished 7 chord is D, F, Ab/G#, Cb/B
At the 4th fret the diminished 7 chord is D#/Eb , F#/Gb, A, C
The diminished 7 chord on the 5th fret is the same as the diminished 7 chord at the 2nd fret etc.
The easiest way to remember the names of the diminished 7 chord is simply to read off the notes contained in the chord. Conversely if you wish to find a particular diminished chord all you need to do is find that note on the fretboard and form the chord arpeggio around it.
Example 59 combines diminished seventh chords with other chord types discussed in section two.
Db Diminished Seventh Arpeggio Over Two Octaves
Example 60 uses the Db diminished seventh arpeggio over two octaves ascending and descending.
