This has already been touched upon but I'll add it anyway. I like doing this for practice to work myself through the various keys.

Dim7ths can also be used as pivot chords to effect a modulation to remote keys, so any note of a dim7th can be lowered a semitone to make a dominant 7th, which can then be used as a V7-1 cadence in the new key.

So if for some reason you wanted to go from C major key to Bb Minor Key, you could play the C dim7th chord and then lower the Gb to F to get an F7th chord, which can then proceed to the tonic chord of Bb Minor.

Even though not all are effective, we can end up with 4 major and 4 minor key modulations just from the one dim7. Very handy if you are stuck trying to get to an unrelated key.

I like experimenting with dim7ths, they are interesting chameleons.

(The C-Cdim7-Dm7-G7 is a really nice sounding progression isn't it.)

yjoh

[i]Music...a joy for life.