For the "locked hands" block chord style, I've noticed that diminished chords can be used as passing chords to get from one chord to another or one melody note to the next if staying on the same chord. What approaches can be used with regards to this? Please provide examples if possible
In this case, the diminished chord is kind of special, in that it works as a passing chord to harmonize all non-chord tones. What I mean by this, and what I think is sort of implied by your question, is that in taking a scale (C major for example), if you harmonize all the notes in this scale, with locked-hands, block-chords style, for the notes C, E, G and A, you'll use an inversion of C6, in closed position, where the top and bottom notes are doubled in an octave, and for the rest of the pitches (D, F, B), you'll use a diminished chord, in closed position, with the top and bottom notes doubled.
So what could you use instead of a diminished chord? As Mark Levine suggests in the jazz piano book, one possible reason that the diminished chord works in this context is that it serves as a type of dominant chord, specifically, a G7b9 without the root (going again with the C major example). So in theory, you could use any combination of notes that work over G7. So for example, I might use D-F-A-B-D, sort of a d minor 6 looking chord, as the second chord, because I know that over G, that creates a G9 chord.
Listening to a top jazz pianist like Ahmad Jamal, Benny Green, or Chick Corea, I find that when and if they use block chords, they'll play many different types of passing chords in that block formation...it seems to me that they experiment and use whichever sounds they like. The note that would be most off-limits is the major seventh of the V chord (going again with the C major example, that would be F#).
OK. In fact this questions is not one but many, depending on the (theory knlowledge) level of the person asking.
To understand how to use a passing chord, one must first understand what is NOT a passing chord.
- In jazz, a passing chord is something different from the iim7-V7-IM7 (in major), or the minor equivalent of iim7b5 -V7alt-ImM7 (Im6) AND THAT IS NOT a substitute chord. (further: in jazz harmony, a diminished 7chord is an incomplete, alt. dominant chord, e.g. G7b9 is G-B-D-F-Ab, and B-D-F-Ab is a Bdim7 chord, i.e., an incomplete G7b9 dominant... but since you asked about passing chords, I'm going to ignore this part of a potential answer).
- In "classical" music (using Schenkerian analysis), a passing chord is a bunch of notes harmonizing a note that either: a) is not on a strong beat, or b) harmonically doesn't play a structural roll.
So, on to the passing dim chords. In a tonal context, the strongest tonal chords are (in order of priority):
you can use a diminished chord as a passing chord between two "functional" chords (in jazz this means between two 2-5-1 chords or their respective substitutions) and in "classical", between two passing notes, or non-structural chords.
Jazz - Say you have in a melody the following: A-B-C, and you are in a C major key. You could harmonize that with Dm7-G7-CM6, or Dm7-Bdim7-Cm6 modulate to minor tonality or Dm7-Bdim7-CM6 (to imply a minor tonality).
Classical - For the sofisticated use of the dim7 chord, check/read p. 421 of the book Harmony and Voice Leading.
For a general treatment of classical and jazz theory (respectivley) see Felix Salzer's "Structural Hearing"(or Schenker's theory) and "The Schillinger System Of Musical Composition". The Schillinger System is not a music theory in itself, but really a methatheory, worth every minute of it!
In "locked hands" style, you can often take a pragmatic voice-leading approach to passing chords. Move what has to move, let what can stay put do so. No need to worry too much about analyzing the result.
Examples of such linear harmony are found in Chopin, many times per page. Start with his opus 10 etudes in minor keys, for instance.
It sounds to me like you are referring to the passing 6/4 chord progression of I(6)-vii(6)-I. Which is very common passing chord. (especially in four part harmony exercises.)