I've been experimenting with some 12-tone rows again recently and found I had to keep pausing to find voicings for stacks of semitones. The guitar isn't really designed for playing such things in close voicing, so you have to make some decisions about octave displacement just to make the things playable. I thought it might be useful to have some of these collected together, so here goes.

Close Voicings

These are 3-note semitone clusters in which one of the semitones is actually played as a semitone -- the other one is either a major seventh or a minor ninth. I found several possibilities on various string groups; note that I'm not trying to be exhaustive here, though I suspect I've probably caught most of them.

The diamond note-shape indicates a fingering I'd only consider viable in higher positions, but you may have longer fingers and/or less tendonitis than me.

Spread Voicings

Things get a bit less awkward if we allow both semitones to expand to either major sevenths or minor ninths, as in the following fingerings. The sound is less crunchy, too:

With most of these we have enough room to add another semitone, giving four-note clusters:

These are pretty extreme sounds and it's tough to find a place for them in a tonal context such as a jazz standard. They're very characteristic of mid-twentieth-century classical music, though, so to get your ear in here's a short piece by the mighty Witold Lutoslawski, packed full of semitones and their close relatives: