Originally Posted by: Fret spiderat the moment the only way to do this i found was using the harmonic minor, cos it has diminished seventh arp and augmented arps.

any other ways guys?

Diminished chords (1, minor 3rd, flat 5th) and Diminished 7th chords (1, minor 3rd, flat 5th, double flat 7th) are essentially "harmonies" of the leading tone of a scale - the 7th degree.

This means they are used as cadential chords: to use as dominant functions, i.e. the chord right before you resolve to tonic (the I -one - chord).

Also because they are symmetrical - same distance between each note in the chord (a minor 3rd) - you can use them as a pivoting chord to modulate to any other key, scale, chord that is one fret below any note in the diminished chord.

Example: in the key of C major the chord built on the 7th degree is a B diminished chord.

B dim =
root = B
min 3rd = D
flat 5th = F

Normally when you play a B dim chord in the key of C major you are suggesting a vii dim chord that is acting as a dominant chord suggesting a return to C major as a resolution (or C minor!).

But you can also think of it as a way to modulate to E flat major. Because the D would act as the 7th degree leading tone and B, D, F (& G sharp if you use a full dim 7th chord) are also part of a D diminished chord.

Or you can play along is C major and after you play the B dim chord look at it like an F dim chord and resolve to G flat major. If you include the G sharp, as I suggested earlier, then you can easily resolve to A minor (which is called a deceptive candence - because it is the relative minor of the original key of C major).

Concrete examples are absolutely indispensible in learning musical concepts.

E|------1---------------------------------------------|
B|-5----1----3----1-----------------------------------|
G|-5----2----1----0-----------------------------------|
D|-5----3----3----2-----------------------------------|
A|-3---------2----3-----------------------------------|
E|----------------------------------------------------|

C major: I - IV - vii dim - I (you could switch to C minor instead!)

E|------1---------3-----------------------------------|
B|-5----1----3----4-----------------------------------|
G|-5----2----1----3-----------------------------------|
D|-5----3----3----5-----------------------------------|
A|-3---------2----------------------------------------|
E|----------------------------------------------------|

C major: I - IV - vii dim - I of E flat

E|------1---------2-----------------------------------|
B|-5----1----3----2-----------------------------------|
G|-5----2----1----3-----------------------------------|
D|-5----3----3----4-----------------------------------|
A|-3---------2----------------------------------------|
E|----------------------------------------------------|

C major: I - IV - vii dim - I of G flat

E|------1---------------------------------------------|
B|-5----1----3----1-----------------------------------|
G|-5----2----1----2-----------------------------------|
D|-5----3----3----2-----------------------------------|
A|-3---------2----0-----------------------------------|
E|----------------------------------------------------|

C major: I - IV - vii dim - I of A minor (you could switch to A major instead!)

The same concept applies to augmented chords except they are built on the 5th degree of the major scale and thus also dominant functions. This can be fairly complicated stuff. Feel free to ask follow up questions. Good luck modulating!