I was wondering what the classical or jazz approach to whole diminished chords is, I understand and use half diminished chords and such, and know you can substitute a dominant 7th chord with a half diminished one but I can't figure out the usage of whole diminished ones

I like the sound of them and can use them with more atonal sounding stuff, can make em work with the whole half scale, as well as just kinda randomly throwing them in wherever it sounds best, mostly when writing creepier stuff, but I can't seem to make them function in a less jarring progression.

it sounds like I hear em in jazz and jazz fusion type stuff like cynic (not sure, my ear isn't really good enough to know) how would you apply them in something like that?
The classical function of diminished sevenths is identical to the classical function of half-diminished sevenths. Both chords are used primarily as either a dominant substitution, or prolongation, or as a tonic prolongation. The diminished 7th is typically found in minor keys, as it is diatonic in the harmonic version of the minor scale. The half diminished 7th is typically found in major keys as it is the diatonic seventh chord built on vii. That being said, both chords can occur in major or minor.

In jazz they can often be used for a similar thing. Diminished 7th chords always resolve really well to a major or minor chord with a root a minor second above. They are often used as chromatic chords, resolving to diatonic triads (Classically analyzed as secondary leading tones).

Another interesting thing about them is their symmetry. Making use of this, you can use them to modulate up a minor third, tritone, or major sixth with relative ease.
thanks man, i didn't realize the diminished 7th was also used as a dominant substitution, and I feel like an idiot for not realizing it was diatonic in harmonic minor cuz I spent quite a while trying to see if it could easily fit in major or natural minor lol, and thanks for the tip about them resolving a minor second down easily. and I figured they could help in resolving and in leading tones, but I still need some work on that. for now I guess I'll just use them more chromatically

and that's part of why I'm so interested in them, I really like having things symmetrical. one of the first things I ever did with em was making a little progression of whole diminished chords ascending in minor thirds with a bass line walking up and down in minor thirds, sound creepy as fuck, i think it's in my profile, called menace or something.

edit: also, what's a prolongation? that's one I haven't heard before
Last edited by The4thHorsemen at Aug 22, 2009,