Sky-Coyote - Sorry about that (bb5 in my post should of course have been bb7) - thanks for the correction!

I realise looking that I also made another mistake when I said that sharpening any note of a diminished 7th chord created a dominant 7th chord - that should have been flattening any note of a diminished 7th chord creates a dominant 7th chord. Thus if we look at Cdim7:

Cdim7 = C Eb Gb A

Flattening the notes one at a time (and rewriting the notes and reordering to make the chord clear) gives:

  1.  Cb Eb Gb A = B D# F# A                      = B7
  2.  C Ebb Gb A = C D Gb A = C D F# A = D F# A C = D7
  3.  C Eb Gbb A = C Eb F A = F A C Eb            = F7
  4.  C Eb Gb Ab = Ab C Eb Gb                     = Ab7
  

Mick